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Abstract

Owing to the recent progress in the field of supportive robotic technologies, interest in the area of active orthoses and exoskeletons has increased rapidly. The first attempts to create such devices took place 40 years ago. Although many solutions have been found since then, many challenges still remain. Works concerning the lower extremities and active orthoses are listed and described in this paper. The research conducted and commercially available devices are presented, and their actuation, hardware, and movements they make possible are described. In addition, possible challenges and improvements are outlined.

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... Such approaches have seen clinical application for rehabilitation within the pediatric population, with improved outcomes observed in gross motor function, walking ability, and step length [2]. However, such approaches are limited in that they can be asymmetrical between the two legs of the patient [3], can have insufficient exertion to provide adequate rehabilitation [4], and can be physically exhausting for the therapist, thereby limiting therapy session length [5]. ...
... In addition, other benefits include improved repeatability in applied torque or motion profile and direct measurement of gait which can be used for automatic quantitative assessment. Many devices are currently available for the adult population, as presented in other review articles [5,6]. Relatively few exoskeletons have been developed for children and each with their own limitations [7,8]. ...
... By equating these two expressions for the inertia and substituting in the calculation for mass in Equation (5) and CoM in Equation (6), it is possible to derive the formula for the moment of inertia as Equation (7). This concludes the derivation of the formula for Equation (7). ...
Article
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Exoskeleton technology has undergone significant developments for the adult population but is still lacking for the pediatric population. This paper presents the design of a hip–knee exoskeleton for children 6 to 11 years old with gait abnormalities. The actuators are housed in an adjustable exoskeleton frame where the thigh part can adjust in length and the hip cradle can adjust in the medial-lateral and posterior-anterior directions concurrently. Proper control of exoskeletons to follow nominal healthy gait patterns in a time-invariant manner is important for ease of use and user acceptance. In this paper, a hybrid zero dynamics (HZD) controller was designed for gait guidance by defining the zero dynamics manifold to resemble healthy gait patterns. HZD control utilizes a time-invariant feedback controller to create dynamically stable gaits in robotic systems with hybrid models containing both discrete and continuous dynamics. The effectiveness of the controller on the novel pediatric exoskeleton was demonstrated via simulation. The presented preliminary results suggest that HZD control provides a viable method to control the pediatric exoskeleton for gait guidance.
... ReWalk is one of the well-known exoskeletons [23] which has recently been approved by FDA [24]. The Hybrid Assistive Limbs (HAL) project [25] is another notable project assisting SCI, stroke, and other patients suffering from impaired bipedal walking. Reviews on exoskeletons, prostheses ,and orthoses are available in the literature [19,[24][25][26][27]. ...
... The Hybrid Assistive Limbs (HAL) project [25] is another notable project assisting SCI, stroke, and other patients suffering from impaired bipedal walking. Reviews on exoskeletons, prostheses ,and orthoses are available in the literature [19,[24][25][26][27]. ...
... For instance, in [50], a 32% ± 9% metabolic cost reduction is reported for post-stroke patients during walking using a tethered exosuit. Readers are referred to comprehensive survey paper for details of these studies [19,[24][25][26][27]31]. ...
Thesis
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Wearable robotic assistive devices have the potential to improve the metabolic efficiency of human locomotion. Developing exoskeletons that can reduce the metabolic cost of human locomotion is challenging, since there is no systematic mechatronic design approach for the design of such exoskeletons. A systematic design approach necessitates a means for a rigorous and fair comparison of effects of different exoskeleton designs and assistance torque profiles on the human metabolic cost of locomotion. Conducting such investigations through human subject experiments with physical devices is generally infeasible, while design studies relying on musculoskeletal models hold high promise in providing effective design guidelines, as the effect of devices and various assistance torques on muscle recruitment and metabolic cost can be studied systematically. In this thesis, a simulation-based design approach is introduced to systematically design exoskeletons that reduce the metabolic cost of locomotion. Along these lines, a Pareto optimization approach is proposed to enable rigorous and fair comparisons of effects of different exoskeletons designs and assistance torques on the metabolic cost of locomotion, under some realistic physical limits on actuator torques. The proposed systematic mechatronics system design approach is demonstrated by introducing a bi-articular exoskeleton design and comparing its efficiency with commonly used mono-articular exoskeletons. In particular, the power consumption of and metabolic rate reduction due to assistance provided by bi-articular and mono-articular hip-knee exoskeletons are optimized simultaneously during unloaded and loaded walking conditions, and rigorous comparison among such devices is presented. Furthermore, the effect of regeneration on the power consumption of exoskeletons and the detrimental effects of inertial properties of exoskeletons on the metabolic cost of locomotion are studied by superposing these effects on the Pareto-front curves. Our results explain the effect of heavy loads on the optimal assistance profiles and provide guidelines on choosing the optimal device configurations under actuator torque limitation, device inertia, and regeneration effects. The multi-criteria comparison of devices indicates that on the one hand, similar assistance levels can be achieved by both exoskeletons; on the other hand, mono-articular exoskeletons demonstrate better performance on reducing the peak reaction forces, while the power consumptions of bi-articular exoskeletons are less affected by the loading of subjects. Furthermore, the inclusion of device inertia results in significantly less detrimental effects on the metabolic cost of subjects and does not affect the Pareto-optimality of solutions for bi-articular exoskeletons, while non-dominated configurations are significantly affected by the device inertia for mono-articular exoskeletons.
... Wearable robots are an emerging technology in many fields such as rehabilitation, assistive devices, human augmentation, and haptics [1], [2], [3]. The physical human-robot interaction (pHRI) interface consists of the mechanical attachment between the user and the robot which is responsible for ensuring safe, comfortable, and effective force transfer [4]. ...
... This work was funded, in part, by the National Science Foundation (NSF) grant numbers 2019704 and 1941260, as well as the NSF Graduate Research Fellowship Program (GRFP) grant number DGE-1610403. 1 such force/torque data provides valuable information about human-robot interaction at a macro level [10], [11], [12], it is insufficient for understanding the exact loads experienced by the human user distributed across the physical interface surface. Assuming six-axis force/torque measurements directly translate to loads sensed by the human incorrectly treats the pHRI attachment as a rigid connection, failing to consider compliance from human soft tissue and robot attachment materials. ...
Conference Paper
Full-text available
Physical human-robot interaction (pHRI) interfaces are responsible for ensuring safe, comfortable, and effective force transfer between wearable devices and their users. However, analysis is often oversimplified by treating the human-robot attachment as a rigid connection and using gross load measurements. As a result, information about the distribution of forces across the human-robot contact surface is lost. In this paper, we present an analysis method to predict distributed loading across a pHRI interface based on a model with discretized elastic elements that account for compliance from human soft tissue and the robot attachment. Stiffness properties of a proxy upper arm are measured with an indenter and used in the pHRI interface model. The analysis is performed assuming a rigid arm model, consistent with the underlying assumption in literature, and repeated using the proposed compliant arm model with measured elastic properties. The distributed loading predicted by the pHRI interface model is validated with measurements from a sensorized upper arm cuff on the Harmony exoskeleton. Our results reveal that a model incorporating compliance at the human-robot attachment is necessary to improve prediction of distributed interface loads. This motivates the need for human-centered analysis which can enable finer control of interaction forces and help design more ergonomic attachment interfaces.
... It has widely used in fields of both military and civil life to enhance people's walking ability and relieve people's fatigue under the condition of heavy load and long-time walking [1]. In the control system of the soft suit exoskeleton, human motion intention recognition plays an important role [2][3][4][5]. ...
... Its parameters include step length and step speed, and the shape of gait can be adjusted according to the requirements of the exoskeleton wearer. A vision-assisted VALOR prototype autonomous gait pattern planning was proposed and validated in [2], with the aim of improving the exoskeleton's adaptability to complex environments. The disadvantage is that this method cannot detect the ground environment in real time. ...
Article
Full-text available
To solve the complexity of the traditional motion intention recognition method using a multi-mode sensor signal and the lag of the recognition process, in this paper, an inertial sensor-based motion intention recognition method for a soft exoskeleton is proposed. Compared with traditional motion recognition, in addition to the classic five kinds of terrain, the recognition of transformed terrain is also added. In the mode acquisition, the sensors’ data in the thigh and calf in different motion modes are collected. After a series of data preprocessing, such as data filtering and normalization, the sliding window is used to enhance the data, so that each frame of inertial measurement unit (IMU) data keeps the last half of the previous frame’s historical information. Finally, we designed a deep convolution neural network which can learn to extract discriminant features from temporal gait period to classify different terrain. The experimental results show that the proposed method can recognize the pose of the soft exoskeleton in different terrain, including walking on flat ground, going up and downstairs, and up and down slopes. The recognition accuracy rate can reach 97.64%. In addition, the recognition delay of the conversion pattern, which is converted between the five modes, only accounts for 23.97% of a gait cycle. Finally, the oxygen consumption was measured by the wearable metabolic system (COSMED K5, The Metabolic Company, Rome, Italy), and compared with that without an identification method; the net metabolism was reduced by 5.79%. The method in this paper can greatly improve the control performance of the flexible lower extremity exoskeleton system and realize the natural and seamless state switching of the exoskeleton between multiple motion modes according to the human motion intention.
... The use of additional sensory channels has not been widely explored in human augmentation exoskeletons. Lower limb active exoskeletons apply forces about the hip, knee, or ankle to assist with joint flexion and extension (Viteckova et al., 2013). When supporting gait, lower limb exoskeletons use repetitive stance-swing cycles to move the body forward (Perry, 1992). ...
... The increase in NSL and speed is not unexpected as energy is added to propel the body and leg forward, affecting the gait dynamics. It has been shown that powered ankle exoskeletons can reduce metabolic cost (Malcolm et al., 2013;Sawicki & Ferris, 2008) and alter gait characteristics, such as increasing NSL and speed (Shi et al., 2019;Viteckova et al., 2013). FI participants increased NSL and speed when the torque was on, regardless of the timing of the cue (Figure 3(a)). ...
Article
Objective This study examined the interaction of gait-synchronized vibrotactile cues with an active ankle exoskeleton that provides plantarflexion assistance. Background An exoskeleton that augments gait may support collaboration through feedback to the user about the state of the exoskeleton or characteristics of the task. Methods Participants ( N = 16) were provided combinations of torque assistance and vibrotactile cues at pre-specified time points in late swing and early stance while walking on a self-paced treadmill. Participants were either given explicit instructions ( N = 8) or were allowed to freely interpret (N=8) how to coordinate with cues. Results For the free interpretation group, the data support an 8% increase in stride length and 14% increase in speed with exoskeleton torque across cue timing, as well as a 5% increase in stride length and 7% increase in speed with only vibrotactile cues. When given explicit instructions, participants modulated speed according to cue timing—increasing speed by 17% at cues in late swing and decreasing speed 11% at cues in early stance compared to no cue when exoskeleton torque was off. When torque was on, participants with explicit instructions had reduced changes in speed. Conclusion These findings support that the presence of torque mitigates how cues were used and highlights the importance of explicit instructions for haptic cuing. Interpreting cues while walking with an exoskeleton may increase cognitive load, influencing overall human-exoskeleton performance for novice users. Application Interactions between haptic feedback and exoskeleton use during gait can inform future feedback designs to support coordination between users and exoskeletons.
... De là peuvent naître des sensations d'inconfort pour l'utilisateur : des irritations sur la peau, des retards entre la réalisation d'une tâche et son intention, des mouvements forcés, des vibrations, du bruit . . . [VKJ13] Pour certains, les exosquelettes d'aujourd'hui ne permettent pas de travailler en synergie avec leur opérateur car il n'y a pas suffisamment d'informations échangées entre les deux acteurs [Che+16]. Face à ce constat, l'utilisation des électromyogrammes (EMG) et des électroencéphalogrammes (EEG) serait une réponse avec un sérieux potentiel pour lire l'intention de mouvement de l'utilisateur. ...
... Tableau récapitulatif de systèmes d'assistance existants[VKJ13].22CHAPITRE 1. CONTEXTE ET OBJECTIFSL'exosquelette possède également des chaussures spéciales équipées de capteurs d'effort, des potentiomètres pour mesurer les angles de rotation, un gyroscope et un accéléromètre montés sur le sac-à-dos pour estimer l'inclinaison du buste. Des électrodes EMG sont placées au niveau de la cuisse de l'utilisateur en vue d'estimer le couple produit par le genou. ...
Thesis
Avec le vieillissement de la population, la sédentarité, l’augmentation des accidents vasculaires cérébraux et autres déficiences motrices, la mobilité est un enjeu mondial primordial. À ce problème, les exosquelettes et les orthèses constituent une réponse technologique possible.Une orthèse est un système pluridisciplinaire qui doit s’adapter au corps de l’utilisateur pour l’assister dans son mouvement. De par sa nature complexe, elle impose à l’utilisateur des contraintes physiques, technologiques et liées à la commande. Les matériaux utilisés, la géométrie, la chaîne de puissance, la chaîne d’information, la morphologie de l’être humain et la nature du mouvement sont autant d’éléments qui influent sur la nature et l’amplitude des contraintes. Si celles-ci sont trop importantes, l’utilisateur va devoir s’adapter et modifier sa démarche en conséquence.Pour prévoir les contraintes physiques appliquées par une orthèse de genou sur un individu au cours d’un mouvement cyclique tel que le squat ou la marche, un simulateur a été développé. Il permet de générer des trajectoires optimales au sens d’une fonction de coût et de calculer les couples articulaires nécessaires à la réalisation du mouvement. Une étude expérimentale a été menée sur plusieurs sujets pour comprendre comment le poids se répartit au cours d’un mouvement de squat. Basé sur ces résultats, un modèle de répartition des efforts a été proposé.
... Lower-limb exoskeletons have been developed for ADLs rehabilitation and assistance [25]. For this purpose, those wearable devices have been designed taking into account the human biomechanics to perform similar lower limb movements [26]. ...
... The mass-spring-damper system implementation in this control strategy has been implemented in rehabilitation and assistance medical applications such as in these works [30,33,34,36]. Additionally, the generated torques for the hip and knee joints obtained in the pilot study provided high-level torque profiles (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) for the knee joint compared to other knee exoskeleton presented in the literature [2,29,32,34]. On the other hand, this torque range does not provide high-level torque profiles for the hip joint [2,38]. ...
Article
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Exoskeletons aim to provide required torques in a patient’s lower limbs generating anatomical patterns. In this sense, this work presents an AGoRA lower limb exoskeleton aimed at rehabilitating patients who suffer hemiparesis. Two control strategies for physical Human-Robot Interaction are tested in a pilot study with a healthy user. On the one hand, the assistance mode uses a gait phase detection to generate a desired gait cycle in the paretic limb. On the other hand, the transparency mode is presented to simulate a back-drivable device using a mass-damper system. As a result, in the assistance mode, torques in the range of (20 - 30 Nm) for the knee and hip joints were generated to complete the user’s gait cycle. Moreover, the user can execute unrestricted movements using the AGoRA exoskeleton in the transparency mode.
... Wearable robotic devices, such as powered exoskeletons, are being designed to assist the elderly population and other patients with locomotion disabilities (stroke survivors, spinal cord injured, cerebral Palsy etc.) [3]. Such devices are characterized by the implementation of traditional electric motors with the large gear reductions necessary to achieve high torques. ...
Conference Paper
Full-text available
Wearable robotic devices are being designed to assist the elderly population and other patients with locomotion disabilities. However, wearable robotics increases the risk from falling. Neuroimaging studies have provided evidence for the involvement of frontocentral and parietal cortices in postural control and this opens up the possibility of using decoders for early detection of balance loss by using electroencephalography (EEG). This study investigates the presence of commonly identified components of the perturbation evoked responses (PEP) when a person is in an exoskeleton. We also evaluated the feasibility of using single-trial EEG to predict the loss of balance using a convolution neural network. Overall, the model achieved a mean 5-fold cross-validation test accuracy of 75.2 % across six subjects with 50% as the chance level. We employed a gradient class activation map-based visualization technique for interpreting the decisions of the CNN and demonstrated that the network learns from PEP components present in these single trials. The high localization ability of Grad-CAM demonstrated here, opens up the possibilities for deploying CNN for ERP/PEP analysis while emphasizing on model interpretability.
... Devices may be machine or user-initiated, have single or multiple actuated joints, and be used as either a single or double leg support. 13 Research has shown that the use of exoskeletons in stroke rehabilitation appears to be feasible [14][15][16][17][18] and safe. 19,20 There was some evidence of improvement in gait and balance outcomes in a 2018 systematic review, 20 however these improvements were not significantly better than with routine therapy, and the varied devices and diverse patient characteristics included in the review limit interpretation of the findings. ...
Article
Full-text available
Introduction Robotic exoskeletons facilitate therapy in upright postures. This study aimed to evaluate potential health-related effects of this therapy for people with severe mobility impairment due to chronic stroke. Methods This quasi-controlled trial with 12 weeks of twice weekly therapy in a free-standing exoskeleton, and 12 weeks follow up, included people dependent for mobility, with stroke at least 3 months prior. The primary outcome was lower limb motor function. A battery of secondary outcomes was evaluated. Results Nine participants were enrolled. There was no change in motor function. There was a significant between phase difference in level of independence with activities of daily living (median post-intervention change = 5, IQR = 0, 10, p = 0.01), and grip strength (affected limb) (median post-intervention change = 1, IQR = 0, 2, p = 0.03). A significant difference was found for quadriceps strength (affected limb) (median change in wait phase = 4, IQR = 2, 7.5, p = 0.01). Participants consistently reported positive perceptions of the therapy. Conclusions Therapy with a free-standing exoskeleton is acceptable to participants and can facilitate improvements in level of independence and grip strength. Restrictions regarding eligibility to use the device, may reduce the clinical application of this therapy for people with stroke.
... For the past few decades, with the development of human-machine interaction and human motion-decoding methods, an advanced technology was developed to bridge the gap between the human and robots (Bonato, 2010). This robotic technology, known as the wearable robot, directly interacts with the human body to enhance the mobility of healthy people (exoskeletons), to treat muscles or skeletal parts which are injured or after the operation (orthosis), or to replace the missing limbs of disabled people (prostheses) (Viteckova et al., 2013;Chadwell et al., 2020). ...
Article
Full-text available
The interaction between human and exoskeletons increasingly relies on the precise decoding of human motion. One main issue of the current motion decoding algorithms is that seldom algorithms provide both discrete motion patterns (e.g., gait phases) and continuous motion parameters (e.g., kinematics). In this paper, we propose a novel algorithm that uses the surface electromyography (sEMG) signals that are generated prior to their corresponding motions to perform both gait phase recognition and lower-limb kinematics prediction. Particularly, we first propose an end-to-end architecture that uses the gait phase and EMG signals as the priori of the kinematics predictor. In so doing, the prediction of kinematics can be enhanced by the ahead-of-motion property of sEMG and quasi-periodicity of gait phases. Second, we propose to select the optimal muscle set and reduce the number of sensors according to the muscle effects in a gait cycle. Finally, we experimentally investigate how the assistance of exoskeletons can affect the motion intent predictor, and we propose a novel paradigm to make the predictor adapt to the change of data distribution caused by the exoskeleton assistance. The experiments on 10 subjects demonstrate the effectiveness of our algorithm and reveal the interaction between assistance and the kinematics predictor. This study would aid the design of exoskeleton-oriented motion-decoding and human–machine interaction methods.
... Wearable support systems (mainly active exoskeletons) can help to close this gap by opening up the possibility to introduce automation solutions to fields traditionally connected to manual labour by incorporating the wearer as source of flexibility while on the other hand reducing the stress for physically demanding tasks [5]. For a long time, the main application area of exoskeletons has been in military and rehabilitation use-cases like supporting physically weak, injured, or disabled people to perform a wide range of motions [6] and whose design criteria differ largely from industrial applications. In recent years companies started using exoskeletons in assembly lines. ...
Chapter
Exoskeletons can support workers on physically demanding tasks, but in industry they lack of acceptance. This contribution gives an insight into design aspects for upper body exoskeletons, especially how active exoskeletons for industrial applications differ from military and medical use-cases. To overcome typical rigid exoskeleton problems, we suggest the use of modular soft-exosuit support systems and therefore checked different types of soft actuation principles for their eligibility for the use on upper body joints. Most promising approach is using two-layered actuators sting of robust fabric with embedded rubber tubes as pressure chambers. By inflating the tubes, it is possible to vary the stiffness of the chambers, which can be effectively used to generate assisting forces and moments at human joints (shoulder, elbow, wrist, finger).
... It uses robotic arms strapped to the ankle and thigh of the patient to simulate the movement at the knee and thigh. The use of robotic arm reduces the overall weight of the device and ease donning and doffing as compared to Lokomat [36]. LOPES (University of Twente, Netherlands) is another TBE consisting of 8 DOF (two for pelvis translation and three revolute joints at each leg) actuated through SEA [37]. ...
Article
Background: With the increasing rate of ambulatory disabilities and rise in the elderly population, advance methods to deliver the rehabilitation and assistive services to patients have become important. Lower limb robotic therapeutic and assistive aids have been found to improve the rehabilitation outcome. Objective: The article aims to present the updated understanding in the field of lower limb rehabilitation robotics and identify future research avenues. Methods: Groups of keywords relating to assistive technology, rehabilitation robotics, and lower limb were combined and searched in EMBASE, IEEE Xplore Digital Library, Scopus, Web of Science and Google Scholar database. Results: Based on the literature collected from the databases we provide an overview of the understanding of robotics in rehabilitation and state of the art devices for lower limb rehabilitation. Technological advancements in rehabilitation robotic architecture (sensing, actuation and control) and biomechanical considerations in design have been discussed. Finally, a discussion on the major advances, research directions, and challenges is presented. Conclusions: Although the use of robotics has shown a promising approach to rehabilitation and reducing the burden on caregivers, extensive and innovative research is still required in both cognitive and physical human-robot interaction to achieve treatment efficacy and efficiency.
... Conventional therapies to recover the gait function impose physical load to the therapists as well as economical burden to the patients. In addition, the outcomes of gait training are often limited by inaccurate gait patterns and incorrect assessment of the patients [5,6]. In order to reduce the burdens, robotic gait training systems have been studied and used [7,8]. ...
Preprint
Full-text available
Background: Aging societies lead to higher demand for gait rehabilitation as age-related neurological disorders such as stroke increase. Since conventional methods for gait rehabilitation are physically and economically burdensome, robotic gait training systems have been studied and commercialized, many of which provided movements confined in the sagittal plane. For better outcomes of gait rehabilitation with more natural gait patterns, however, it is desirable to provide pelvic movements in the transverse plane. In this study, a robotic gait training system capable of pelvic motions in the transverse plane was used to evaluated the effect of the pelvic motions on stroke patients. Method: Healbot T, which is a robotic gait training system and capable of providing pelvic movements in the transverse plane as well as flexion/extension of the hip and knee joints and adduction/abduction of the hip joints, is introduced and used to evaluate the effect of the pelvic movement on gait training of stroke patients. Experiment: 23 stroke patients with hemiparesis participated in this study and were assigned into two groups. Pelvis-on group was provided with pelvic motions whereas no pelvic movement was allowed for pelvis-off group during 10 sessions of gait trainings in Healbot T. EMG signals and interaction forces as well as the joint angles of the robot were measured. Gait parameters such as stride length, gait period, cadence, and walking speed were measured after gait training. Result: 37.5 % lower interaction forces of pelvis were observed in the pelvis-on group than the pelvis-off group. Furthermore, the interaction forces at the thighs and calves of both groups showed significant decrease. The EMG signals of gluteus medius of the pelvis-on group increased by 77.2 %. Furthermore, statistically significant increases in various muscles were measured in the pelvis-on group during the stance phase. Conclusion: Gait training using a robotic gait training system with pelvic movements was conducted to study the effects of lateral and rotational pelvic movements in gait training of stroke patients. The pelvic movements made gait training less interfered by the exoskeleton while stimulating the voluntary muscle activation during the stance phase. Clinical trial registration: KCT0003762, 2018-1254, Registered 28 October 2018, https://cris.nih.go.kr/cris/search/search_result_st01_kren.jsp?seq=14310
... In the field of health; exoskeletons and robotic systems are used in the rehabilitation of individuals who have partially or completely lost their walking ability and to provide walking support. Also in recent years; It has also started to be used to support soldiers, firemen, heavy industrial workers, search and rescue workers and jobs that need more power than manpower [3,4]. Also, it is benefited from bipedal robots in some areas that push the human limits and that are dangerous such as heavy industry, nuclear and space research [5]. ...
... The exoskeletons are wearable robots that assist the patient in standing up, sitting down and walking independently [26][27][28][29][30]. A detailed review of exoskeletons and their application in rehabilitation is given in [31]. There are few limitations associated with these exoskeletons regarding their daily life use and affordability. ...
Article
Full-text available
Rehabilitation and assistive technologies are touching new bounds of excellence due to the advent of more user friendly human–machine interfaces (HMI) and ergonomic design principles. Among the most fundamental movements which are required in performing activities of daily living is the sit and stand motion, a device is proposed in this study which enables a patient to perform his activities of daily living (ADL) tasks by enabling them to sit, stand and move without the need of an assistant. The device, in this study, is proposed to be activated by an electroencephalogram (EEG) based intention acquisition system. The intention is acquired from eye blinks. The EEG based intention detection system converts eye blinks to respective commands after classification of eye blink signals collected using EMOTIVE® EPOCH⁺ headset. These control commands then trigger the control algorithm which then actuates and controls the system states. For the later, two control schemes namely proportional integral derivative (PID) control and sliding mode control (SMC) are tested in this study. The simulation and experimental results are given. The experimental setup consists of an offline EEG signal classification module, Simulink® model and the prototype of the actual device. It is concluded that SMC performs far better than PID for control of the assistive device in ensuring patient comfort during motion.
... Wearable support systems (mainly active exoskeletons) can help to close this gap by opening up the possibility to introduce automation solutions to fields traditionally connected to manual labour by incorporating the wearer as source of flexibility while on the other hand reducing the stress for physically demanding tasks [5]. For a long time, the main application area of exoskeletons has been in military and rehabilitation use-cases like supporting physically weak, injured, or disabled people to perform a wide range of motions [6] and whose design criteria differ largely from industrial applications. In recent years companies started using exoskeletons in assembly lines. ...
Conference Paper
Absence from work caused by overloading the musculoskeletal system lowers the life quality of the worker and gains unnecessary costs for both the employer and the health system. Classical (rigid link) body-worn exoskeletons can help to reduce critical loading but show many disadvantages, preventing exoskeletons from extensive use in industrial environment. The presented PowerGrasp system is a very robust modular soft-robotic arm exosuit sting of robust fabric with embedded rubber tubes as pressure chambers and soft-electronics and who's design is capable to overcome the critical limiting factors of classical exoskeletons. By inflating the tubes via pressure-control valves, it is possible to vary the stiffness of the chambers, which can be effectively used to generate assisting forces and moments at human joints. By using a joint based pressure control, it is possible to decrease the physical demand of overhead working for the wearer. Although the system is designed for industrial overhead assembly, it can also be used in rehabilitation, craftsmanship and construction due to its portable and stand-alone concept. For assessing the impact of the PowerGrasp system, the raise of about 50 percent was shown. Finally, an evaluation study of the overall system has been conducted, showing very high user acceptance and usability.
... Applications for wearable robots are emerging in many fields such as rehabilitation, assistive devices, human augmentation, and haptics [1][2][3]. Safety and comfort are major factors in the use of such robots, especially with sensitive populations where these aspects correspond to the high rate of disuse of assistive devices [4]. Both safety and comfort are directly affected by the robot's control and its manifestation across physical human-robot interaction (pHRI) interfaces, consisting of the mechanical attachment between the user and the robot [5]. ...
Article
Full-text available
Measurement of interaction forces distributed across the attachment interface in wearable devices is critical for understanding ergonomic physical human–robot interaction (pHRI). The main challenges in sensorization of pHRI interfaces are (i) capturing the fine nature of force transmission from compliant human tissue onto rigid surfaces in the wearable device and (ii) utilizing a low-cost and easily implementable design that can be adapted for a variety of human interfaces. This paper addresses both challenges and presents a modular sensing panel that uses force-sensing resistors (FSRs) combined with robust electrical and mechanical integration principles that result in a reliable solution for distributed load measurement. The design is demonstrated through an upper-arm cuff, which uses 24 sensing panels, in conjunction with the Harmony exoskeleton. Validation of the design with controlled loading of the sensorized cuff proves the viability of FSRs in an interface sensing solution. Preliminary experiments with a human subject highlight the value of distributed interface force measurement in recognizing the factors that influence ergonomic pHRI and elucidating their effects. The modular design and low cost of the sensing panel lend themselves to extension of this approach for studying ergonomics in a variety of wearable applications with the goal of achieving safe, comfortable, and effective human–robot interaction.
... The different maneuvers are commanded by the user based on postural information measured by the device. Slavka et al [60] reviewed about commercially available devices, and their actuation, hardware, and movements they make possible are described. Ying et al [61] proposed a new approach to estimate GH-c using measurements of shoulder joint angles and cable lengths. ...
Article
This paper describes the design and kinematic analysis of a 5 DOF upper limb powered robotic exoskeleton for rehabilitation of the patients who survived stroke and the elderly who do not have enough strength to move their limbs freely. It was observed that the existing upper extremity exoskeletons were bulky and heavy which made them limited to applications and the complexity of the system increases with the number of DOF's considered. Therapies in rehabilitation process doesn't require much complex designs. This create a need to develop an exoskeleton which is economical, light weight device to provide more dexterity than the existing one. The proposed wearable exoskeleton builds upon our research experience in wire driven manipulators and design of rehabilitative systems.
... Di erent lower limb orthoses are dedicated to train patients to recover strength and coordination. Recent reviews have presented a comprehensive overview of lower limb robotic orthoses for rehabilitation [16,47,50,51,52,53,54], including those focusing on the ankle joint [12,20,26]. Rehabilitation devices can be classi ed as portable robots worn by the human limbs, or platform based devices. ...
Thesis
Neuro-motor deficiencies following a stroke can lead to a poor control of the ankle joint during walking. One of the major symptoms that illustrate this deficiency is the foot drop that appears along the swing phase. In recent years, robotic rehabilitation devices have been the subject of numerous research projects around the world. These devices can enable the patient to achieve the same levels of functional recovery as those achieved with conventional rehabilitation while reducing the workload of physical therapists.This thesis deals with the problem of the control of an actuated ankle-foot orthosis intended for the walking assistance of paretic patients with motor deficiencies at the ankle level. The originality of our work lies in the consideration of the evolution of the gait cycle in the controlled assistance. The other remark of our work lies in the development of control laws that guarantee the patient safety and a good performance in terms of trajectory tracking accuracy, robustness with respect to parametric uncertainties, variability between subjects and external disturbances.Three control approaches for reference trajectory tracking are proposed. These approaches have the advantage of not requiring the prior identification of the orthosis-human system parameters. The reference trajectory is generated in real time with an algorithm that exploits the interaction of the feet with the ground to detect the sub-phases of the gait cycle.The first approach proposed is a model reference adaptive control that adapts the assistance torque according to the tracking error. This control uses a projection function to limit the values of the adaptive parameters of the control law. A saturation operator is also introduced to limit the assistance torque. The second approach is an adaptive proxy-based sliding mode control that can change the damping effect at the ankle during the transition from the stance phase to the swing phase. The adaptive nature of this controller makes it possible to compensate for changes in system dynamics during the gait cycle, while the use of the sliding mode makes it possible to guarantee good performance in terms of trajectory tracking. The third approach is an active disturbance rejection control. An extended state observer is used to estimate the disturbances to which the orthotic-human system is subjected in order to compensate for their effects and improve trajectory tracking performance. For each control approach, a Lyapunov stability study is conducted.The three control approaches have been validated experimentally with the participation of healthy subjects and paretic patients. Regarding the latter, the clinical evaluations were carried out in collaboration with the Department of Physical Medicine and Rehabilitation of the Mondor Hospital.
... To address some of the issues associated to MSDs, one of the solutions consists in providing the workers Physical Assistance Devices (PAD) such as exoskeletons. Initially developed in rehabilitation or military purpose, innovative solutions have then been specifically developed to answer the industrial needs [6] [7][8] [9]. Through the past years, different technologies have been investigated by manufacturers: some exoskeletons (the active ones) are working with actuators or engines while the others (the passive ones) are using the energy conservation principle stored up into elastic band or composite springs [10]. ...
Preprint
The aim of this study was to evaluate the Hapo ms, a passive upper limbs exoskeleton developed to assist workers for tasks with arms in front of the body. Twelve participants had to perform a static task, a manual handling task and a load carrying task two times: with and without the exoskeleton. In all cases subjective (perceived effort in arm and back areas, comfort) and objective (muscular activity, postural balance) criteria were evaluated. Results have shown a decrease in anterior deltoid (-12 to -18% depending of the task) and in biceps brachii (-19% to -33% depending of the task) muscular activity. No significant difference was pointed out in back muscle and postural balance was not significantly perturbed due to the wear of the exoskeleton. Finally, perceived effort reduction was observed during the three tasks (except in back area for task 1). To conclude, the Hapo ms seems well adapted to assist upper arms during tasks with arms in front of the body.
... Low mobility during STS causes weakness and loss of physical power [7]. It is also very important for people of this group to walk with the conditions of maintaining balance and not falling down [8], [9]. Providing the appropriate conditions during a walk and also for STS transfer creates the independence of these people. ...
Article
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Assistive device equipment can improve the performance of sit-to-stand (STS), standing, and walking of people with lower limb disability. The motorized assistive device is usually expensive and the use of another assistive device also makes an excessive force in the upper and lower extremity during (STS) transfer, which is not desirable for patients. In addition, only a few number of the non-motorized assistive devices that support all three phases; namely, sit-to-stand, standing, and walking are available. Consequently, improving and creating the new technology seems essential in this case. In this paper, the design procedure of saddle-assistive device is described in order to make use of the linear actuator in (STS) transfer and walk. Experimental results orientation of the shoulder during (STS) was recorded in the lab. Then, based on this analysis and simulation, saddle-assistive devices(S-AD) were designed and prototyped. Function prototype of the (S-AD) was done in the lab on a healthy person in (STS) and walking and then was compared with (STS) in normal mode. It is proposed due to the integration of the three phases in one device. Other advantages are force reduction on lower limbs, creating conditions of stability, and independence for patients with lower limb disability.
... Conventional therapies to recover the gait function impose physical load to the therapists as well as economical burden to the patients. In addition, the outcomes of gait training are often limited by inaccurate gait patterns and incorrect assessment of the patients [5,6]. In order to reduce the burdens, robotic gait training systems have been studied and used [7,8]. ...
Article
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Background Aging societies lead to higher demand for gait rehabilitation as age-related neurological disorders such as stroke and spinal cord injury increase. Since conventional methods for gait rehabilitation are physically and economically burdensome, robotic gait training systems have been studied and commercialized, many of which provided movements confined in the sagittal plane. For better outcomes of gait rehabilitation with more natural gait patterns, however, it is desirable to provide pelvic movements in the transverse plane. In this study, a robotic gait training system capable of pelvic motions in the transverse plane was used to evaluate the effect of the pelvic motions on stroke patients. Method Healbot T, which is a robotic gait training system and capable of providing pelvic movements in the transverse plane as well as flexion/extension of the hip and knee joints and adduction/abduction of the hip joints, is introduced and used to evaluate the effect of the pelvic movement on gait training of stroke patients. Gait trainings in Healbot T with and without pelvic movements are carried out with stroke patients having hemiparesis. Experiment Twenty-four stroke patients with hemiparesis were randomly assigned into two groups and 23 of them successfully completed the experiment except one subject who had dropped out due to personal reasons. Pelvis-on group was provided with pelvic motions whereas no pelvic movement was allowed for pelvis-off group during 10 sessions of gait trainings in Healbot T. Electromyography (EMG) signals and interaction forces as well as the joint angles of the robot were measured. Gait parameters such as stride length, cadence, and walking speed were measured while walking on the ground without assistance of Healbot T after gait training on 1st, 5th, and 10th day. Result Stride length significantly increased in both groups. Furthermore, cadence and walking speed of the pelvis-on group were increased by 10.6% and 11.8%. Although interaction forces of both groups except the thighs showed no differences, EMG signals from gluteus medius of the pelvis-on group increased by 88.6% during stance phase. In addition, EMG signals of biceps femoris, gastrocnemius medial, and gastrocnemius lateral of the pelvis-on group increased whereas EMG signals of the pelvis-off group except gastrocnemius lateral showed no difference after gait trainings. Conclusion Gait training using a robotic gait training system with pelvic movements was conducted to investigate the effects of lateral and rotational pelvic movements in gait training of stroke patients. The pelvic movements affected to increase voluntary muscle activation during the stance phase as well as cadence and walking speed. Clinical trial registration KCT0003762, 2018-1254, Registered 28 October 2018, https://cris.nih.go.kr/cris/search/search_result_st01_kren.jsp?seq=14310&ltype=&rtype
... Incorrect application of the control strategy may result in the robot impeding or even harming the human movement. Therefore, accurate and real-time recognition of locomotion modes is the foundation of exoskeleton control, which is of great significance [2][3][4]. ...
Article
Full-text available
This paper proposes a hierarchical support vector machine recognition algorithm based on a finite state machine (FSM-HSVM) to accurately and reliably recognize the locomotion mode recognition of an exoskeleton robot. As input signals, this method utilizes the angle information of the hip joint and knee joint collected by inertial sensing units (IMUs) on the thighs and shanks of the exoskeleton and the plantar pressure information collected by force sensitive resistors (FSRs) are used as input signals. This method establishes a framework for mode transition by combining the finite state machine (FSM) with the common locomotion modes. The hierarchical support vector machine (HSVM) recognition model is then tightly integrated with the mode transition framework to recognize five typical locomotion modes and eight locomotion mode transitions in real-time. The algorithm not only reduces the abrupt change in the recognition of locomotion mode, but also significantly improves the recognition efficiency. To evaluate recognition performance, separate experiments are conducted on six subjects. According to the results, the average accuracy of all motion modes is 97.106% ± 0.955%, and the average recognition delay rate is only 25.017% ± 6.074%. This method has the benefits of a small calculation amount and high recognition efficiency, and it can be applied extensively in the field of robotics.
... The usefulness of the ADRC technique for tracking trajectories has been evaluated over many upper and lower limb robotic rehabilitation exoskeletons in recent years. A lower limb gait trajectory tracking was recently achieved using LESO [39,40] and proved to be more successful than PID. Several enhancements have recently been made to improve the existing LESO-based architecture of ADRC to track accurate trajectories. ...
Article
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In this paper, a combined control strategy with extended state observer (ESO) and finite time stable tracking differentiator (FTSTD) has been proposed to perform flexion and extension motion repetitively and accurately in the sagittal plane for shoulder and elbow joints. The proposed controller improves the tracking accuracy, performs state estimation, and actively rejects disturbance. A sinusoidal trajectory as an input has been given to a two-link multiple-input multiple-output (MIMO) upper limb robotic rehabilitation exoskeleton (ULRRE) for a passive rehabilitation purpose. The efficacy of the controller has been tested with the help of performance indices such as integral time square error (ITSE), integral square error (ISE), integral time absolute error (ITAE), and integral of the absolute magnitude of error (IAE). The system model is obtained through the Euler–Lagrangian method, and the controller’s stability is also given. The proposed controller has been simulated for ±20% parameter variation with constant external disturbances to test the disturbance rejection ability and robustness against parametric uncertainties. The proposed controller has been compared with already developed ESO-based methods such as active disturbance rejection control (ADRC), nonlinear active disturbance rejection control (NLADRC), and improved active disturbance rejection control (I-ADRC). It has been found that the proposed method increases tracking performance, as evidenced by the above performance indices.
... Discussion on healthcare robotics often focuses on [2] surgical robotics for interventions [3], robot prosthetics [4,5], rehabilitation robotics [6][7][8] and social robots for behavioral therapeutics and education [9][10][11]. Service robots and robotic technologies embedded in current and future ICU machines are also relevant. ...
Preprint
Robotics is widely seen as a key enabling technology for the society of tomorrow. This review examines the role of robotics and intelligent medical devices in Intensive Care Medicine. Demographics predict that more elderly patients will need to be treated with fewer healthcare personnel, calling for innovations in ICU management. Robotics is a key enabling technology for the 21st century and may help to smooth the foreseeable workload/manpower disparity in medicine. Studying the application of robotics in the ICU in a manner beneficial for patients and accepted by intensive care team is therefore desirable. Financial sustainability is essential for the introduction of these new technologies to the ICU. This study therefore assesses the state of the art in robotics in intensive care medicine and identifies opportunities for progress, using an observational approach in a teaching hospital ICU in combination with an in-depth review of the literature and a survey of the market. Tasks potentially amenable to robotics are identified, their acceptability to patients and caregivers are examined and their quantitative contribution to future management of an intensive care unit is assessed.
... These devices provide a robotic physical aid, which can be used in different scenarios, such as performing tasks on the treadmill or directly on the floor [1,2]. Within these two scenarios, the main goal of the use of LLEs has often been classified into three categories: (1) rehabilitation, (2) assistance, and (3) augmentation [3,4]. Rehabilitation exoskeletons are aimed to support physical therapy tasks, which require demanding training to provoke neural plasticity, build muscle strength, promote balance, and regain healthy patterns [5]. ...
Article
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Exoskeletons have been assessed by qualitative and quantitative features known as performance indicators. Within these, the ergonomic indicators have been isolated, creating a lack of methodologies to analyze and assess physical interfaces. In this sense, this work presents a three-dimensional relative motion assessment method. This method quantifies the difference of orientation between the user’s limb and the exoskeleton link, providing a deeper understanding of the Human–Robot interaction. To this end, the AGoRA exoskeleton was configured in a resistive mode and assessed using an optoelectronic system. The interaction quantified a difference of orientation considerably at a maximum value of 41.1 degrees along the sagittal plane. It extended the understanding of the Human–Robot Interaction throughout the three principal human planes. Furthermore, the proposed method establishes a performance indicator of the physical interfaces of an exoskeleton
... To identify sources that provide more explicit information on lower limb exoskeletons in military use, we further reviewed searches focused on lower limb exoskeletons [1][2][3][4]. However, none of the articles focused on the lower limb exoskeleton in military applications. ...
Chapter
With the development of new wearable technologies, the use of exoskeletons is gradually gaining ground in the world's advanced militaries. The aim of this paper is to explore the current status of exoskeletons and describe the requirements of exoskeletons for military use towards the specifics of use. The most important movement of a soldier in the field is walking, and therefore the analysis of the current state will focus primarily on lower limb exoskeletons and their subsystems. The paper will compare active and passive lower limb exoskeletons and their use in military practice. Subsequently, the requirements for individual subsystems of the mechatronic system of the exoskeleton will be specified. Sensor subsystems, actuator subsystems, control subsystems and man-machine interface will be described. Recommendations for further analysis and use of exoskeletons in the military can thus contribute not only to increased performance but also to the safety of the users themselves - individual soldiers.
... Exoskeletons have been widely used for military and rehabilitation purposes, and recently there has been a growing interest in their occupational application Viteckova et al., 2013), particularly for overhead work (Grazi et al., 2020;Iranzo et al., 2020;Kim et al., 2018aKim et al., , 2018bLo and Xie, 2012;Pacifico et al., 2020;Rashedi et al., 2014;Yin et al., 2020). In this sense, several commercial passive exoskeletons have been presented by the Ottobock company (Ottobock, 2019). ...
Article
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Overhead work is an important risk factor associated with musculoskeletal disorders of the neck and shoulder region. This study aimed to propose and evaluate a passive head/neck supporting exoskeleton (HNSE) as a potential ergonomic intervention for overhead work applications. Fourteen male participants were asked to perform a simulated overhead task of fastening/unfastening nut in 4 randomized sessions, characterized by two variables: neck extension angle (40% and 80% of neck maximum range of motion) and exoskeleton condition (wearing and not wearing the HNSE). Using the HNSE, significantly alleviated perceived discomfort in the neck (p-value = 0.009), right shoulder (p-value = 0.05) and left shoulder (p-value = 0.02) and reduced electromyographic activity of the right (p-value = 0.005) and left (p-value = 0.01) sternocleidomastoid muscles. However, utilizing the exoskeleton caused a remarkable increase in right (p-value = 0.04) and left (p-value = 0.05) trapezius electromyographic activities. Performance was not significantly affected by the HNSE. Although the HNSE had promising effects with respect to discomfort and muscular activity in the static overhead task, future work is still needed to investigate its effect on performance and to provide support for the generalizability of study results.
... For instance, most potential LLLE users find cost to be a major barrier when purchasing an LLLE. They also require their LLLEs to be lightweight, have minimal metabolic requirements, can withstand prolonged hours of operation, is portable, accessible for daily use, natural in shape and movement, adaptable, have good device performance, possess anthropomorphic features, is safe, not noisy, and can be handled by the user (Ball et al., 2014, Jin-gang et al., 2015Herr, 2009;Viteckova et al., 2013;Wolff et al., 2014;Mertz, 2012;Huo et al., 2016;Young and Ferris, 2016). However, it is a challenge for designers to design LLLEs that meet all the requirements of users. ...
Article
Creativity is very important in the conceptual design stage for mechatronic products. The innovation and development of mechatronic products usually cover different knowledge domains. Traditionally, ideation comes intuitively or logically. However, this depends on the creativity and ideas of the designer. As such, tools; such as Pugh's total design process (PTDP) and the theory of inventive problem solving (TRIZ); have emerged to help designers design and develop their products. Therefore, this paper attempted to present a conceptual design strategy; namely PDS-TRIZ; by combining product design specification (PDS) and TRIZ to improve PTDP. A locomotive lower limb exoskeleton (LLLE); a device used to assist paraplegics regain walking ability; was used to demonstrate the capability of the proposed PDS-TRIZ method. Our study proved that the proposed PDS-TRIZ could be used to develop conceptual designs for mechatronic products.
... Therefore this paper endeavors to look into the global market research and consumer experience sphere to project the overall view of the introduced classifications related to smart wearable devices and technology in the health care system. Wearable devices can be classified based on how they interact with the body and how they are worn [21,22]. The classification based on the first perspective is shown in Figure 6(a) which was proposed by the International Electronical Committee (IEC) standard. ...
Article
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High quality and efficient medical service is one of the major factors defining living standards. Developed countries strive to make their healthcare systems as efficient and cost-effective as possible. Remote medical services are a promising approach to lower medical costs and, at the same time, accelerating diagnosis and treatment of diseases. Internet of things (IoT) has the power to connect several devices, users, databases, etc., in a unified manner. Internet of medical things (IoMT) is some type of IoT designed to facilitate medical services. Using IoMT, many of the medical tasks, such as chronic disease monitoring, disease diagnosis, etc., can be realized remotely, leading to lower healthcare costs and better services. This paper is devoted to the role of artificial intelligence (AI) in recent advances on IoMT. Hardware requirements and recent articles proposing solutions for IoMT using AI are reviewed. A comprehensive list of major benefits and challenges is presented as well. Wearable medical devices (WMDs) are also investigated. The WMDs classification is also performed based on their technology. Market share and its anticipated growth for different types of WMDs are also analyzed for the first time. Moreover, common applications of AI in IoMT are reviewed and then classified based on their usage. The paper is closed with the conclusion and possible directions for future works.
... Regular exoskeleton use has the potential to maintain and even improve some of the benefits associated with traditional rehabilitation modalities for a number of SCI-related comorbidities [11]. However, several barriers currently exist related to the practical use of exoskeletons as mobility devices: walking independently can be dangerous for individuals with compromised balance control; the limited speed of walking is prohibitive [12]; as is the requirement to use a walking aid such as elbow crutches, preventing users from carrying anything around the home or work environment [13]. A recent systematic review advocated the use of robotic exoskeletons in SCI rehabilitation as part of a multi-modality approach, with clear recommendations that its use should not be prioritised over other therapies [14]. ...
Article
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Background Robotic assisted gait training (RAGT) uses a powered exoskeleton to support an individual's body and move their limbs, with the aim of activating latent, pre-existing movement patterns stored in the lower spinal cord called central pattern generators (CPGs) to facilitate stepping. The parameters that directly stimulate the stepping CPGs (hip extension and ipsilateral foot unloading) should be targeted to maximise the rehabilitation benefits of these devices.AimTo compare the biomechanical profiles of individuals with a spinal cord injury (SCI) and able-bodied individuals inside the ReWalkTM powered exoskeleton and to contrast the users' profiles with the exoskeleton.Methods Eight able-bodied and four SCI individuals donned a ReWalkTM and walked along a 12-meter walkway, using elbow crutches. Whole-body kinematics of the users and the ReWalkTM were captured, along with GRF and temporal-spatial characteristics. Discreet kinematic values were analysed using a Kruskall-Wallis H and Dunn's post-hoc analysis. Upper-body differences, GRF and temporal-spatial characteristics were analysed using a Mann-Whitney U test (P
... For more detailed descriptions and comparisons of exoskeleton hardware, see Refs. [23][24][25][26][27]. ...
Article
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This paper proposes a novel hybrid controller for promoting safe human-robot interaction. The hybrid controller modifies a model-based impedance controller such that it uses impedance control but switches to sliding mode control under non-nominal conditions. Each control law is formulated with an inner-loop controller for feedback linearization and an outer-loop feedback controller for trajectory tracking. The outer-loop feedback torque is theoretically proven to have a smaller magnitude in hybrid control than in impedance control under an assumed condition, suggesting it may be the safer approach. To validate the mathematical assumption and purpose of the controller, a walking experiment is conducted where a healthy able-bodied subject using a lower-limb exoskeleton is randomly subjected to either hybrid or impedance control. Perturbations are induced through sudden changes in treadmill speed, resulting in operation outside nominal conditions for 15.9% of the experiment. The assumption made in the theory holds true for the majority of the experiment, failing only 14.3% of the time. The main results show a statistically significant reduction in average feedback torque magnitudes by 7.9%. This is accomplished without drastically affecting gait, with joint angle root-mean-square differences being 0.36° for the hip and 0.64° for the knee. This demonstrates how the hybrid controller can achieve similar gait patterns with lower feedback torque magnitudes, suggesting it is a promising alternative to impedance control.
Chapter
In this chapter, the lower limb exoskeleton is studied. The roles of the exoskeleton both as a measurement device for studying human locomotion and as an assistive device that restores the human ability to walk are discussed. Particular attention is given to the investigation of the role of the pressure sensors and other devices that allow us to measure normal reactions at the contact points with the supporting surface and also detect these contacts. The way the geometry of the supporting surface affects the sensors system of the robot is considered, and new designs for feet sensor system are proposed. These include elastic foot, a foot with actuated sensors, and a foot with spring-damper systems.
Chapter
The chapter approaches the issues of modeling the process of load lifting by a person while wearing an exoskeleton. The classification of existing gravitational compensation systems for industrial exoskeletons is shown, as well as examples of its use. A mathematical model of lifting a person's load in the exoskeleton is presented, as well as numerical parameters are calculated. It is shown that the introduction of an elastic element reduces the level of energy consumption during work, and can also facilitate the level of the worker. Industrial exoskeleton prototype design is presented. A particular focus is given to studying the influence of the gravity compensator on the magnitude of the moments generated by the electric drives of the hip and knee joints. It is shown that the use of gravity compensators enables to reduce significantly the load on electric drives.
Article
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Lower-limb exoskeletons have undergone significant developments for aiding in the ambulation of adults with gait impairment. However, advancements in exoskeletons for the pediatric population have comparatively been lacking. This paper presents a newly developed joint actuator designed to drive the hip and knee joints of a pediatric lower-limb exoskeleton. The performance requirements associated with the actuators were determined based on a target audience of children ages 6–11 years old. The developed actuators incorporate a hybrid belt-chain transmission driven by a frameless brushless DC motor. One actuator underwent benchtop testing to evaluate its performance with respect to their torque production, bandwidth properties, backdrivability in terms of inertia and friction characteristics, speed capabilities, and operational noise levels. As a preliminary validation, a set of actuators were placed in a prototype orthosis to move a pediatric test dummy in gait tracking via state-feedback control. The results showed that the newly developed actuators meet the design specifications and are suitable for use in the pediatric exoskeleton being developed.
Article
Due to the lag problem of traditional sensor acquisition data, the following movement of exoskeleton robots can affect the comfort of the wearer and even the normal movement pattern of the wearer. In order to solve the problem of lag in exoskeleton motion control, this paper designs a continuous motion estimation method for lower limbs based on the human surface electromyographic (sEMG) signal and achieves the recognition of the motion intention of the wearer through a combination of the deep belief network (DBN) and random forest (RF) algorithm. First, the motion characteristics of human lower limbs are analyzed, and the hip–knee angle and sEMG signal related to lower limb motion are collected and extracted; then, the DBN is used in the dimensionality reduction of the sEMG signal feature values; finally, the motion intention of the wearer is predicted using the RF model optimized by the genetic algorithm. The experimental results show that the root mean square error of knee and hip prediction results of the combined algorithm proposed in this article improved by 0.2573° and 0.3375°, respectively, compared to the algorithm with dimensionality reduction by principal component analysis, and the single prediction time is 0.28 ms less than that before dimensionality reduction, provided that other conditions are exactly the same.
Article
This paper presents a newly developed lower-limb exoskeleton tested for walking assistance. The novel exoskeleton design methodology uses additive manufacturing and a parametrized model based on user anthropometrics to give a person-specific custom fit. The process is applied to average children and a healthy adult, and a prototype device is fabricated for the adult to validate the feasibility of the approach. The developed prototype actuates the hip and knee joints without restricting hip abduction-adduction motion. To test usability of the device and evaluate walking assistance, user torque, mechanical energy generated, and muscle activation are analyzed in an assisted condition where the subject walks on a level treadmill with the exoskeleton powered. This is compared to an unassisted condition with the exoskeleton unpowered and a baseline condition with the subject not wearing the exoskeleton. Comparing assisted to baseline conditions, torque magnitudes increased at the hip and knee, mechanical energy generated increased at the hip but decreased at the knee, and muscle activations decreased in the Biceps Femoris and increased in the Vastus Lateralis. The presented preliminary results are inconclusive on whether the newly developed exoskeleton can assist in walking though show promise for basic usability of the device.
Article
В статье рассматриваются экзоскелеты – это носимые роботизированные системы, которые объединяют человеческий интеллект и силу робота. Эта статья впервые вводит общую концепцию экзоскелетов и рассматривает несколько типичных экзоскелетов нижних конечностей в трех основных приложениях (реабилитация походки, помощь в локомотивном движении человека и увеличение силы человека), а также обеспечивает системный обзор приобретения намерения движения владельца и стратегий контроля за экзоскелетов нижних конечностей.
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The availability of fiber conductors that can be stretched to large extents without significantly changing resistance or conductivity could enable the advances of elastic conductors as electronic interconnects, electronic skins, stretchable sensors, wearable systems, and medical robots. Therefore, the preparation of fiber conductors with high stretchability is crucial to the development of flexible electronic devices. This review summarizes the advances in constructing fiber conductors with an emphasis on recent developments of buckled structural design, fabrication methodologies, and strategies, with the ultimate goal of achieving good stability of resistance or conductivity at large strains. This review classifies the buckled fiber conductors into inner buckling and outer buckling, and related examples are summarized, providing a context that buckled fiber conductors are geared towards applications in electrical interconnects, wearable systems, and smart medical robotics. The present challenges in this area are critically evaluated and our perspectives for improving the performance of the buckled fiber conductors for future applications are presented.Graphic abstract
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The surface electromyography (SEMG) based exoskeleton presents a new opportunity for human augmentation and rehabilitation. Developing an efficient exoskeleton in real‐time is challenging as each individual's muscles and joint forces are unique. The aim of this research article is to analyze and evaluate the design of the lower limb exoskeleton during the squatting movement in a simulated environment to address problems concerning the development of a functional exoskeleton for an individual. An exoskeleton was designed in SolidWorks CAD software and imported into AnyBody Modelling Software (AMS). Thereafter, the performance of 3D designed exoskeleton was evaluated by placing various loads (0:5:25 kg) on both the shoulders of the human musculoskeletal. The results show the force in the knee muscles with the assistance of the exoskeleton were reduced significantly by 65.18–97.20% in the biceps femoris, 50.01–33.16% in the rectus femoris, 41.87–28.31% in the vastus lateralis, 42.25–28.78% in the vastus medialis, 7.28–22.91% in gluteus medius, and 22.54–13.13% in semitendinosus. The force in the knee joint was reduced by 44.04–31.43% as the load increases. Individual muscle force estimated from the SEMG signal and AMS during squatting was also compared for validation. The developed model helps in understanding the load effects on different muscles and provides useful information for the construction of an individual's optimized exoskeleton.
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The exoskeleton has emerged as a promising technology to enhance humans’ strength and boost users’ efficiency. In order to provide congruent human–machine interaction for assisting the users, exoskeletons should have knowledge of human’s planned action and accordingly command the robot by the designed controller. It means the ubiquitous aspect of exoskeletons lies on motion intent understanding and active compliance control. In the last decade, extensive research has been conducted on the two topics. However, no major breakthrough has been made. Thus, a systematic review and analysis on this very subject is of great significance in developing exoskeletons. Within this context, this review first surveys the history of lower limb exoskeletons to summarize the various technologies for realizing transparent human exoskeleton coordination. Then, an overview about motion intent understanding and compliance control strategies are presented in detail. Furthermore, the future trend and research directions are also outlined.
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An exoskeleton system can be an effective ergonomic intervention for mitigating the risks of developing work-related musculoskeletal disorders, yet little attention is given to the effects of its application on physical risk factors and subjective responses. Therefore, the objective of this study was to examine the effects of a passive exoskeleton system on spinal biomechanics and subjective responses during manual repetitive handling tasks among construction workers. Muscle activity of the Thoracic Erector Spinae (TES), Lumbar Erector Spinae (LES) at L3 vertebrae level, Rectus Abdominis (RA), and External Oblique (EO) during the repetitive handling tasks were measured by surface electromyography (sEMG). Additionally, the Borg categorical rating scale (Borg CR 10), local perceived pressure (LPP), and system usability scale (SUS) were used to measure the ratings of perceived discomfort, perceived musculoskeletal pressure, and system usability, respectively. Our results found that: (1) the use of the passive exoskeleton system significantly reduced LES muscle activity (11–33% MVC), with a greater reduction in LES muscle activity (32.71% MVC) for the heaviest lifting load; (2) the use of the passive exoskeleton system significantly reduced perceived discomfort scores (42.40%) of the lower back for the heaviest lifting load; (3) increased lifting load significantly increased LPP scores of the shoulder, lower back, and leg body parts; and (4) majority of the participants rated the passive exoskeleton system as having acceptable usability. The findings of these results indicate that the developed passive exoskeleton system could reduce the internal muscle force, extensor moments, and spinal forces in the lumbar region.
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Flexible assistive device has become an active research topic in recent years due to their promising application prospect in rehabilitation and medical care. Existing devices suffer from the balance between wearable lightness and control effectiveness. This paper introduces a cable-driven lower limb assistive device with a demonstration system for walking assistance. We rely on plantar pressure sensors to determine the gait phase and employ pose sensors to obtain the trajectory of the hip joint angle. We model the human lower limb based on the Lagrangian method and employ the PID algorithm to control the motor’s drive torque during the swing phase. Simulation results demonstrate the effectiveness of the control algorithm on the model’s trajectory tracking and the robustness to disturbance of the flexible device to provide partial walking assistance. Additionally, a software demonstration system based on Unity 3D is designed to monitor the wear’s motion status in real-time, which provides visual feedback for better rehabilitation training.
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Phase-variable-based approaches are emerging in the control of lower-limb wearable robots, such as exoskeletons and prosthetic legs. However, real-time smooth estimation of the gait phase within each gait cycle remains an open problem. This paper presents a novel method for real-time continuous gait phase estimation during walking. The proposed framework consists of three subsystems: real-time kinematic data collection, gait phase variable estimation, and online adaptation of individual kinematics through backward data segmentation of completed gait strides. It is worth noting that we introduce an online learning mechanism for extracting and learning gait features from previous strides, in contrast with offline parameter tuning. The proposed basic gait model is initialized by human average data and is incrementally refined as a function of the individual gait features over different walking speeds. This provides a framework for long-term personalized control. Furthermore, the phase variable is constructed through the thigh angle measured by an inertial measurement unit. The resulting simple sensor system improves the usability of the proposed technique in wearable robotics. Validation experiments with seven healthy subjects, including treadmill walking and free level-ground walking, were conducted to evaluate the performance of the proposed method. In treadmill validation, the root-mean-square error (RMSE) of the phase estimator was 4.14 ± 1.68% for steady speeds, while it was 6.77 ± 2.29% for unsteady-speed walking. In level-ground validation, the average RMSE of the phase estimator was 4.59 ± 1.76%. Preliminary experiments were also conducted using a single-joint hip exoskeleton to demonstrate the usability of our method in lower-limb wearable robots.
Chapter
The chapter approaches the issues of modeling the process of load lifting by a person while wearing an exoskeleton. The classification of existing gravitational compensation systems for industrial exoskeletons is shown, as well as examples of its use. A mathematical model of lifting a person's load in the exoskeleton is presented, as well as numerical parameters are calculated. It is shown that the introduction of an elastic element reduces the level of energy consumption during work, and can also facilitate the level of the worker. Industrial exoskeleton prototype design is presented. A particular focus is given to studying the influence of the gravity compensator on the magnitude of the moments generated by the electric drives of the hip and knee joints. It is shown that the use of gravity compensators enables to reduce significantly the load on electric drives.
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The use of exoskeletons in gait rehabilitation implies user‐oriented and efficient responses of exoskeletons' controllers with adaptability for human‐robot interaction. This study investigates the performance of a bioinspired hybrid control, the Feedback‐Error Learning (FEL) controller, to time‐effectively track user‐oriented gait trajectories and adapt the exoskeletons' response to dynamic changes due to the interaction with the user. It innovates with a controller benchmarking analysis. FEL combines a proportional‐integral‐derivative (PID) feedback controller with a three‐layer neural network feedforward controller that learns the inverse dynamics of the exoskeleton based on real‐time feedback commands. FEL validation involved able‐bodied subjects walking with knee and ankle exoskeletons at different gait speeds while considering gait disturbances. Results showed that the FEL control accurately (tracking error <7%) and timely (delay <30 ms) tracked gait trajectories. The feedforward controller learned the inverse dynamics of the exoskeletons in a time compliant for clinical use and adapted to variations in the gait trajectories, such as speed and position range, while the feedback controller compensated for random disturbances. FEL was more accurate and time‐effective controller for tracking gait trajectories than a PID control (error <27%, delay <260 ms) and a lookup table feedforward combined with PID control (error <17%, delay >160 ms). These findings aligned with FEL's time‐effectiveness favors its use in wearable exoskeletons for repetitive gait training.
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This paper presents the development of a prototype of an active orthosis for lower limbs. The proposed orthosis is an orthopedical device with the main objective of providing walking capacity to people with partial or total loss of limbs movements. In order to design the kinematics, dynamics and the mechanical characteristics of the prototype, the biomechanics of the human body was analized. The orthosis was projected to reproduce the movements of human gait. The movements of the joints of the orthosis are controlled by DC motors equipped with mechanical reductions, whose purpose is to reduce rotational speed and increase the torque, thus generating smooth movements. An embedded electronic system for sensory data acquisition and motor control was projected. The gait movements of the orthosis will be controlled by high level commands from a human-machine interface based on processings of electroencephalogram signals, speech recognition or joystick.
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In this paper, the kinematic analysis of constructed assistive robotic leg for rehabilitation of patients who encounter the neurological injury is presented. In order to design an efficient new mechanism, studies were carried out to distinguish the human architecture and dynamics. In the study, the motion of a healthy physical subject in walking situation of 1 km/h speed was recorded. Thereafter, a novel robotic leg mechanism was developed to produce similar motion. The robotic leg is driven by a single actuator to drive both the hip and the knee joints mechanism. In order to verify the robot motion with respect to human motion, kinematic analysis of all robot's joints and links are formulated and are simulated in MATLAB software. The results obtained from the kinematic analysis of the developed assistive robotic system show that its motion conforms to the motion and dynamics of a healthy human. Keywords -Kinematic analysis, assistive robotic leg, lower extremity exoskeleton, hemiplegic and hemiparetic patient.
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We developed an active ankle-foot orthosis AAFO that controls dorsiflexion/plantarflexion of the ankle joint to prevent foot drop and toe drag during hemiplegic walking. To prevent foot slap after initial contact, the ankle joint must remain active to minimize forefoot collision against the ground. During late stance, the ankle joint must also remain active to provide toe clearance and to aid with push-off. We implemented a series elastic actuator in our AAFO to induce ankle dorsiflexion/plantarflexion. The activator was controlled by signals from force sensing register FSR sensors that detected gait events. Three dimensional gait analyses were performed for three hemiplegic patients under three different gait conditions: gait without AFO NAFO, gait with a conventional hinged AFO that did not control the ankle joint HAFO, and gait with the newly-developed AFO AAFO. Our results demonstrate that our newly-developed AAFO not only prevents foot drop by inducing plantarflexion during loading response, but also prevents toe drag by facilitating plantarflexion during pre-swing and dorsiflexion during swing phase, leading to improvement in most temporal-spatial parameters. However, only three hemiplegic patients were included in this gait analysis. Studies including more subjects will be required to evaluate the functionality of our newly developed AAFO.
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While most mobility options for persons with paraplegia or paraparesis employ wheeled solutions, significant adverse health, psychological, and social consequences result from wheelchair confinement. Modern robotic exoskeleton devices for gait assistance and rehabilitation, however, can support legged locomotion systems for those with lower extremity weakness or paralysis. The Florida Institute for Human and Machine Cognition (IHMC) has developed the Mina, a prototype sensorimotor robotic orthosis for mobility assistance that provides mobility capability for paraplegic and paraparetic users. This paper describes the initial concept, design goals, and methods of this wearable overground robotic mobility device, which uses compliant actuation to power the hip and knee joints. Paralyzed users can balance and walk using the device over level terrain with the assistance of forearm crutches employing a quadrupedal gait. We have initiated sensory substitution feedback mechanisms to augment user sensory perception of his or her lower extremities. Using this sensory feedback, we hypothesize that users will ambulate with a more natural, upright gait and will be able to directly control the gait parameters and respond to perturbations. This may allow bipedal (with minimal support) gait in future prototypes.
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In this study, we developed an active ankle-foot orthosis (AAFO) which could control dorsiflexion/plantarflexion of the ankle joint to prevent foot drop and toe drag during walking. To prevent foot slap after initial contact, the ankle joint needs to be actively controlled to minimize forefoot collision with the ground. During late stance, the ankle joint also needs to be controlled to provide toe clearance and to help push-off. 3D gait analyses were performed on a hemiplegic patient under three different gait conditions: gait without AFO(NAFO), gait with the conventional hinged AFO without controlling ankle joint (HAFO), and gait with the developed AFO(AAFO). Results showed that AAFO could prevent not only foot drop by the proper plantarflexion during loading response but also toe drag by sufficient amount of plantarflexion in pre-swing and reasonable dorsiflexion during swing phase, enhancing all temporal gait parameters. The present results indicated that the developed AAFO might have more clinical benefits to treat foot drop and toe drag in hemiplegic patients, comparing with conventional AFOs.
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A standing style transfer system, ABLE, is designed to assist a person with disabled lower limbs to travel in a standing position, to stand up from and sit down in a chair, and to go up and down steps. The ABLE system comprises three modules: a pair of telescopic Lofstrand crutches, a powered lower extremity orthosis, and a pair of mobile platforms. In this paper, the telescopic Lofstrand crutch is mainly discussed. This crutch has no actuator, and its length is switched between two levels; it assists the person when standing up and sitting down in the short length state, while it maintains the body stability in a standing position when traveling in the long length state. The experimental results related to the traveling in the standing position and standing up motion confirm the design's effectiveness.
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The aim of this article is to introduce the robotic orthosis Lokomat (that was developed to automate the treadmill training rehabilitation of locomotion for spinal cord injured and stroke patients) to the Functional Electrical Stimulation research community, and to report on our newly conducted research. The article first illustrates Lokomat's use in rehabilitation, then focuses on different control aspects and algorithms, and finally describes our efforts to develop a neural network model of the spinal locomotor centers. This model was further used to derive a neural based locomotion controller for the Lokomat.
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The IHMC Mobility Assist Exoskeleton is a robotic suit that a user can wear for strength augmentation or gait generation. This first generation exoskeleton prototype focuses on providing walking assistance to persons with lower extremity paralysis. The main goal is to successfully enable a person that cannot walk without assistance to walk in a straight line a distance of 15 feet. When in disable assist mode this prototype will rely on the user to provide balance control, and thus an external means for balancing will be required, such as crutches or a walker. Power and control is off board and supplied to the exoskeleton by means of a tether. Rotary series elastic actuators (RSEAs), which have high force fidelity and low impedance were designed to power the joints. This paper describes the design, test results, future work and potential applications of the exoskeleton.
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Although electromechanical-assisted gait training after stroke seems to be effective, in the absence of a direct comparison between electromechanical devices it is not clear which device may be the most effective for recovery of walking. The aim of this study was therefore to compare the effects of different devices used in gait training after stroke. We searched the Cochrane Stroke Group Trials Register, CENTRAL, MEDLINE, EMBASE, CINAHL, AMED, SPORTDiscus, PEDro, COMPENDEX and INSPEC. In addition, we hand-searched relevant conference proceedings, trials and research registers, checked reference lists and contacted authors to identify further trials. Randomized studies were included. Authors independently selected trials for inclusion, assessed trial quality and extracted the data. Data were extracted with the help of a standardized data extraction form. Data were pooled for meta-analysis. The primary outcome was the proportion of patients walking independently. We included 18 trials involving 885 patients. We found significantly higher rates of independent walking in end-effector compared with exoskeleton-based training (p = 0.03). Complication rates in both groups were comparable. The results suggest that the type of electromechanical-assisted device might influence the outcome of gait rehabilitation after stroke.
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The differences found in the patients' kinematic gait patterns during the application of functional compensation on the lower limb showed significant differences regarding the subjects' usual gait. In both patients rapid adaptations were observed and new motor commands were learnt necessary for managing the exoskeleton with the constraints imposed on the limb. The benefits of the correct release of the knee in both instances is clear evidence of approximating their gait patterns to the normality pattern depicted in Figure 27, with the compensations of the biomimetic actuation system by applying intermittent impedance (K1 and K2). The GAIT exoskeleton made it possible for patient S1 to walk for the first time without compensation with the hip movement, necessary with the knee-locking orthosis. Assistance to the extension of the knee actuator using energy recovery is obvious and is effectively reached before contact with the ground, as can be observed in the mean values of Figure 27, when a low and constant gait speed is maintained. It is uncertain what percentage of
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This paper discusses the design of a new, minimally constraining, passively supported gait training exoskeleton known as ALEX II. This device builds on the success and extends the features of the ALEX I device developed at the University of Delaware. Both ALEX (Active Leg EXoskeleton) devices have been designed to supply a controllable torque to a subject's hip and knee joint. The current control strategy makes use of an assist-as-needed algorithm. Following a brief review of previous work motivating this redesign, we discuss the key mechanical features of the new ALEX device. A short investigation was conducted to evaluate the effectiveness of the control strategy and impact of the exoskeleton on the gait of six healthy subjects. This paper concludes with a comparison between the subjects' gait both in and out of the exoskeleton.
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This paper describes a powered lower-limb orthosis that is intended to provide gait assistance to spinal cord injured (SCI) individuals by providing assistive torques at both hip and knee joints, along with a user interface and control structure that enables control of the powered orthosis via upper-body influence. The orthosis and control structure was experimentally implemented on a paraplegic subject (T10 complete) in order to provide a preliminary characterization of its capability to provide basic walking. Data and video is presented from these initial trials, which indicates that the orthosis and controller are able to effectively provide walking within parallel bars at an average speed of 0.8 km/hr.
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In this paper we present the alpha-prototype of a novel pediatric ankle robot. This lower-extremity robotic therapy module was developed at MIT to aid recovery of ankle function in children with cerebral palsy ages 5 to 8 years old. This lower-extremity robotic module will commence pilot testing with children with cerebral palsy at Blythedale Childrens Hospital (Valhalla, NY), Bambino Gesu Children's Hospital (Rome, Italy), Riley Children's Hospital (Indianapolis, IN). Its design follows the same guidelines as our upper-extremity robots and adult anklebot designs, i.e. it is a low friction, backdriveable device with intrinsically low mechanical impedance. We show the ankle robot characteristics and stability range. We also present pilot data with healthy children to demonstrate the potential of this device.
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This work introduces a new driven gait orthosis (DGO) based on the pneumatical exoskeleton leg for locomotor training. This device can drive the lower-limb of a patient in a physiological way on the moving treadmill following the given gait which fits to the individual needs. Therefore, it can help a patient who suffers lower-limbs paralysis to recover his walking ability. Mechanisms were designed based on the optimization from the view of human gait and the Ergonomics. Displacement sensors were mounted to allow a closed-loop control consequently to make each limb’s motion as similar as possible to that of the human specimen. Each actuator is controlled by an algorithm, which consists of fuzzy and bang-bang. This solution allowed the existing strong nonlinearities to be easily managed with high response. The satisfying experiments results demonstrated the effect of the hybrid algorithm.
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With over 600 thousand people each year surviving a stroke, it has become the leading cause of serious long-term disability in the United States [1], [2]. The adverse financial and social conditions attributed to stroke have prompted researchers and entrepreneurs to explore the viability of rehabilitation robots. The Powered Ankle Foot Orthosis (PAFO) utilizes robotic tendon technology and supports motion with a single degree of freedom, ankle rotation in the Sagittal plane. Motion capture data, robot sensor data, and functional 6 minute walk data were collected on three stroke subjects. All subjects had some positive changes in their key gait variables while using the PAFO. These changes were more dramatic while harnessed and using a treadmill as opposed to walking over ground. Robot sensor data showed significant improvements on key variables for the three subjects. Motion capture data showed improvements in knee range of motion for subject 1, and the 6 minute walk data showed an increase in distance walked for subjects 1 and 3. Comfort, stability, and robustness proved to be critical design parameters for developing a gait therapy robot capable of collecting repeatable data with low variability.
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Background A large proportion of patients with spinal cord injury (SCI) regain ambulatory function. However, during the first 3 months most of the patients are not able to walk unsupported. To enable ambulatory training at such an early stage the body weight is partially relieved and the leg movements are assisted by two therapists. A more recent approach is the application of robotic based assistance which allows for longer training duration. From motor learning science and studies including patients with stroke, it is known that training effects depend on the duration of the training. Longer trainings result in a better walking function. The aim of the present study is to evaluate if prolonged robot assisted walking training leads to a better walking outcome in patients with incomplete SCI and whether such training is feasible or has undesirable effects. Methods/Design Patients from multiple sites with a subacute incomplete SCI and who are not able to walk independently will be randomized to either standard training (3-5 sessions per week, session duration maximum 25 minutes) or an intensive training (3-5 sessions per week, session duration minimum 50 minutes). After 8 weeks of training and 4 months later the walking ability, the occurrence of adverse events and the perceived rate of exertion as well as the patients' impression of change will be compared between groups. Trial registration This study is registered at clinicaltrials.gov, identifier: NCT01147185.
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Hemiparesis after stroke often leads to impaired ankle motor control that impacts gait function. In recent studies, robotic devices have been developed to address this impairment. While capable of imparting forces to assist during training and gait, these devices add mass to the paretic leg which might encumber patients' gait pattern. The purpose of this study was to assess the effects of the added mass of one of these robots, the MIT's Anklebot, while unpowered, on gait of chronic stroke survivors during overground and treadmill walking. Nine chronic stroke survivors walked overground and on a treadmill with and without the anklebot mounted on the paretic leg. Gait parameters, interlimb symmetry, and joint kinematics were collected for the four conditions. Repeated-measures analysis of variance (ANOVA) tests were conducted to examine for possible differences across four conditions for the paretic and nonparetic leg. The added inertia and friction of the unpowered anklebot had no statistically significant effect on spatio-temporal parameters of gait, including paretic and nonparetic step time and stance percentage, in both overground and treadmill conditions. Noteworthy, interlimb symmetry as characterized by relative stance duration was greater on the treadmill than overground regardless of loading conditions. The presence of the unpowered robot loading reduced the nonparetic knee peak flexion on the treadmill and paretic peak dorsiflexion overground (p < 0.05). Our results suggest that for these subjects the added inertia and friction of this backdriveable robot did not significantly alter their gait pattern.
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Ankle foot orthoses (AFOs) can be used to ameliorate the impact of impairments to the lower limb neuromuscular motor system that affect gait. Existing AFO technologies include passive devices with fixed and articulated joints, semi-active devices that modulate damping at the joint and active devices that make use of a variety of technologies to produce power to move the foot. Emerging technologies provide a vision for fully powered, untethered AFOs. In this dissertation, a novel portable powered ankle-foot orthosis (PPAFO) cabable of providing untethered assistance during gait is presented. The PPAFO provides both plantarflexor and dorsiflexor torque assistance via a bi-directional pneumatic rotary actuator. The system uses a portable pneumatic power source (compressed CO2 bottle) and embedded electronics to control the motion of the foot. Experimental data from two impaired and five healthy subjects were collected to demonstrate design functionality. The impaired subjects had bilateral impairments to the lower legs that caused weakness to the plantarflexors, in one case, and to the dorsiflexors in the other. Data from the healthy walkers demonstrated the PPAFO’s capability to provide correctly timed plantarflexor and dorsiflexor assistance during gait. The results from the impaired subjects demonstrated the PPAFO’s ability to provide functional assistance during gait.
Conference Paper
Repetitive task-oriented exercises are accepted in traditional gait rehabilitation and have given rise to driven gait orthoses, but both methods suffer from limited rehabilitation time for the patient. The presented device proposes a control strategy and implementation unique for a mobile rehabilitation exoskeleton as well as results from initial subject testing. This anthropomorphically designed device has knee and hip joints that are actuated in the sagittal plane using hydraulic actuators. The presented control strategy allows the user or therapist to directly specify the level of rehabilitation assistance desired between complete machine control and a zero impedance joint. The device was experimentally tested on three chronic stroke patients with noticeable gait improvements based on the metric of joint flexion. Other results of step time and step length are presented that do not demonstrate as clear improvements but these are believed to be a function of the limited patient testing time.
Conference Paper
Spinal cord injuries leave thousands of patients confined to wheelchairs, resulting in a life of severely limited mobility. This condition also subjects them to the risk of secondary injuries. Because exoskeletons are externally driven machines in which the actuation is coupled to the person’s joints, they offer an ideal method to help paraplegics walk. The exoskeleton presented here is a mobile, battery powered device that uses hydraulically actuated hip and knee joints in the sagittal plane to move a patient’s joints. The control strategy mimics standard human walking using foot sensors to determine the walking state. This activates position control of the joints to follow standard walking trajectories based on clinical gait analysis data. Initial patient testing of the device showed that the exoskeleton enabled one incomplete paraplegic to significantly improve his gait function and three complete paraplegic patients to walk.
Conference Paper
Gait training of stroke survivors can help in retraining their muscles and improving their gait pattern. Robot assisted gait training (RAGT) was developed for stroke survivors using ALEX and force-field controller, which use assist-as-needed paradigm for rehabilitation. In this paradigm undesirable gait motion is resisted and assistance is provided towards the desirable motion. The force-field controller achieves this paradigm by applying forces at the foot of the subject. Two stroke survivors participated in a 15-day gait training study each with ALEX. The results show that by the end of the training the gait pattern of the patients was improved towards healthy subjects gait pattern. Improvement is seen as increase in the size of the patientspsila gait pattern, increase in knee and ankle joint excursions and increase in their walking speed on the treadmill.
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Commercial lower limb prostheses or orthotics help patients achieve a normal life. However, patients who use such aids need prolonged training to achieve a normal gait, and their fatigability increases. To improve patient comfort, this study proposed a method of predicting gait angle using neural networks and EMG signals. Experimental results using our method show that the absolute average error of the estimated gait angles is 0.25°. This performance data used reference input from a controller for the lower limb orthotic or prosthesis controllers while the patients were walking.
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This paper describes the design, control, and testing of a Human Muscle Enhancer (HME) system that will augment the muscle capabilities of subjects requiring partial lower-limb weight-bearing gait support. The HME described in this paper is a pneumatically actuated quick connecting exoskeleton system that attaches to the foot and hip area of the body, thus "closing" the lower body kinematic chain. Control of the system is achieved by using encoders at the knee joints and Myo-Pneumatic (MP) Sensors implanted into the shoes and outer garments of the human. To test this design concept, a lower body exoskeleton test fixture has been fabricated. The test fixture mimics the human leg with the top cylinder providing the body weight on the leg. Another cylinder acts as leg muscles to provide the adjustable human reaction of the leg. Preliminary open and closed loop control tests have been performed that demonstate the capability of controlling the HME using the MP sensors.
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Power-Assist for lower-limb is expected by many physically weak persons to assist their daily activities. It is important for the power-assist robots that the assist motion is generated based on users motion intention. This paper presents a muscle-model-oriented EMG-based (electromyogram-based) control method to activate a lower-limb power-assist robot according to the users motion intention since the EMG directly reflects the users muscle activities. In the proposed method, a matrix which expresses the relationship between the muscle activities and the generating joint torque is applied to estimate the users motion intention in real-time. The effectiveness of the proposed control method was evaluated by performing experiments.
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We developed a new ankle foot orthosis (AFO) using artificial muscle. In AFO two pressure sensors are arranged in the bottom of the foot. One is located on the toe and other is located on the heel. The control consists of four control sequences such that (1) when the heel touches down on the floor, the pressure of artificial muscle goes to zero gradually, (2) when the toe touches down on the floor after the touch down of the heel, the pressure of artificial muscle is still off, (3) when the heel leaves from the floor, the pressure of artificial muscle is zero, (4) when the toe leaves from the floor, the pressure of artificial muscle becomes a certain value, hence, the artificial muscle is shortened. From the experimental data of a disabled patient it is revealed that this control law yields the faster walking and the shorter swing length. Also, especially, it is clarified that in the action shown by (2) above the plantar flexion control is very important for early recovery of walking ability. In this paper we focus our attention to the development of a new control law to improve the rehabilitation performance based on the plantar flexion control.
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This document proposes a new ankle-foot orthosis (AFO) for Achilles tendon ruptures. The patient can walk with a fixed ankle with the help of a mechanical brake on the active AFO. The mechanism is described, and gait test results using a prototype AAFO reveal the importance of controlling the ankle brake friction electrically.
Chapter
Robotic gait rehabilitation faces many challenges regarding ankle assistance, body weight support and physical human-robot interaction. This paper reports on the development of a gait rehabilitation exoskeleton prototype intended as a platform for the evaluation of design and control concepts in view of improved physical human-robot interaction. The performance of proxy-based sliding mode control as a “robot-in-charge” control strategy is evaluat both in simulation and in experiments on a test setup. Compared to PID control, test results indicate good tracking performance and in particular safe system behavior.
Conference Paper
We have proposed wearable walking support system. In this paper to validate the usefulness of proposed system, the standing up motion, one of the hardest activities of daily life is analyzed and the usefulness of proposed method is discussed. Experimental results show the validity of the system
Conference Paper
This paper describes experimental results obtained for level walking using an active ankle foot orthosis (AAFO) for a ruptured Achilles tendon. The sole of the AAFO is equipped with a servomotor. The actuator can switch the upright and the forward stepping posture of the patient. In gait trials, 1. the use of the AAFO made it possible for the patient to walk without the help of crutches with the ankle in a fixed position. 2. Joint kinematics and stick pictures at a walking speed of 1 km per hour were analyzed. 3.The cross-correlation coefficient between the ankle angle and the EMG signal of the lower leg was small.
Conference Paper
In this paper, we propose a gait generation concept for rehabilitation, in which GaitGen, a gait pattern generator is introduced. The concept of GaitGen will be explained. GaitGen aims to provide objective gait planning for rehabilitation. Gait-related studies have been carried out for the validation and enhancement of GaitGen. Motion capture system has been used for gait database collection. An established equation of normalized gait parameters has been studied via GAITRite. The paper ends with a summary of results, findings, and future works.
Conference Paper
A new set of lower limb orthoses was developed for the WalkTrainer project. This mobile reeducation device for paralyzed people allows overground gait training combining closed loop electrical muscle stimulation and lower limb guiding while walking. An active body weight support system offers precise body weight unloading during locomotion. A 6 DOF parallel robot moves the pelvis in any desired position and orientation. The lower extremity orthosis is composed of two key parts. First, a purely passive lightweight exoskeleton acts as the interface between the human leg and the machine. A 1 DOF knee orthotic joint is also designed to prevent hyperextension. Second, the active part - composed of a mechanical leg equipped with motors and sensors - is located behind each human leg, with its base fixed to the WalkTrainer base frame. The two kinematic chains are connected with appropriate linkages at the thigh and the ankle joint. Actuation of the hip, knee and ankle joints is thus provided for their flexion/extension axis. The active mechanism operates only within the sagittal plane and guides the ankle-foot subsystem. Thigh and shank add/abduction movements are possible and even essential since the pelvis moves in a 3D space. This achievement prevents the scissors effect while allowing natural walking motion at the other joints. This paper describes the design and development of the lower extremity orthosis. Starting from a biomechanical approach, the needed actuation and the mechanical structure are discussed as well as the interface between the patient and the robot.
Conference Paper
This paper presents the design, analysis, and a clinical application of a reconfigurable, parallel mechanism based, force feedback exoskeleton for the human ankle. The device can either be employed as a balance/proprioception trainer or configured to accommodate range of motion (RoM)/strengthening exercises. The exoskeleton can be utilized as a clinical measurement tool to estimate dynamic parameters of the ankle and to assess ankle joint properties in physiological and pathological conditions. Kinematic analysis and control of the device are detailed and a protocol for utilization of the exoskeleton to determine ankle impedance is discussed. The prototype of the device is also presented.