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Exoskeleton: The New Horizon of Robotic Assistance for Human Gait

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Abstract

An exoskeleton is an active mechanical device that is anthropomorphic in nature, is “worn” by an operator, fits closely to his or her body, and works in concert with the wearer’s movements. Generally, the term “exoskeleton” is used to describe a device augmenting the performance of an able-bodied wearer. In contrast, the term “active orthosis” is described as a device that is used to increase the ambulatory ability of a person with disability, for example, someone suffering from a leg pathology. Occasionally, however, the term “exoskeleton” is also used to describe certain assistive devices that enclose the majority of the lower limbs (Dollar and Herr, 2008).

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Training leads to increased neuronal excitability, decreased inhibition and different types of neuronal plasticity. Most studies focus on cortical plastic changes after cerebral lesions or in healthy humans. In this study, we investigate cortical excitability and plastic changes after a three month period of HAL® exoskeleton supported treadmill training in patients with chronic incomplete spinal cord injury by means of electrophysiological measurements and functional magnetic resonance imaging. Here we report preliminary results of four patients.
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Objective: This review examines the utility of current active, powered, wearable lower limb exoskeletons as aids to rehabilitation in paraplegic patients with gait disorders resulting from central nervous system lesions. Methods: The PRISMA guidelines were used to review literature on the use of powered and active lower limb exoskeletons for neurorehabilitative training in paraplegic subjects retrieved in a search of the electronic databases PubMed, EBSCO, Web of Science, Scopus, ProQuest, and Google Scholar. Results: We reviewed 27 studies published between 2001 and 2014, involving a total of 144 participants from the USA, Japan, Germany, Sweden, Israel, Italy, and Spain. Seventy percent of the studies were experimental tests of safety or efficacy and 29% evaluated rehabilitative effectiveness through uncontrolled (22%) or controlled (7%) clinical trials. Conclusions: Exoskeletons provide a safe and practical method of neurorehabilitation which is not physically exhausting and makes minimal demands on working memory. It is easy to learn to use an exoskeleton and they increase mobility, improve functioning and reduce the risk of secondary injury by reinstating a more normal gait pattern. A limitation of the field is the lack of experimental methods for demonstrating the relative effectiveness of the exoskeleton in comparison with other rehabilitative techniques and technologies.
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Stroke significantly affects thousands of individuals annually, leading to considerable physical impairment and functional disability. Gait is one of the most important activities of daily living affected in stroke survivors. Recent technological developments in powered robotics exoskeletons can create powerful adjunctive tools for rehabilitation and potentially accelerate functional recovery. Here, we present the development and evaluation of a novel lower limb robotic exoskeleton, namely H2 (Technaid S.L., Spain), for gait rehabilitation in stroke survivors. H2 has six actuated joints and is designed to allow intensive overground gait training. An assistive gait control algorithm was developed to create a force field along a desired trajectory, only applying torque when patients deviate from the prescribed movement pattern. The device was evaluated in 3 hemiparetic stroke patients across 4 weeks of training per individual (approximately 12 sessions). The study was approved by the Institutional Review Board at the University of Houston. The main objective of this initial pre-clinical study was to evaluate the safety and usability of the exoskeleton. A Likert scale was used to measure patient's perception about the easy of use of the device. Three stroke patients completed the study. The training was well tolerated and no adverse events occurred. Early findings demonstrate that H2 appears to be safe and easy to use in the participants of this study. The overground training environment employed as a means to enhance active patient engagement proved to be challenging and exciting for patients. These results are promising and encourage future rehabilitation training with a larger cohort of patients. The developed exoskeleton enables longitudinal overground training of walking in hemiparetic patients after stroke. The system is robust and safe when applied to assist a stroke patient performing an overground walking task. Such device opens the opportunity to study means to optimize a rehabilitation treatment that can be customized for individuals. This study was registered at ClinicalTrials.gov ( https://clinicaltrials.gov/show/NCT02114450 ).
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Unlabelled: Historically, persons with paralysis have limited options for overground ambulation. Recently, powered exoskeletons have become available, which are systems that translate the user's body movements to activate motors to move the lower limbs through a predetermined gait pattern. As part of an ongoing clinical study (NCT01454570), eight nonambulatory persons with paraplegia were trained to ambulate with a powered exoskeleton. Measurements of oxygen uptake (VO2) and heart rate (HR) were recorded for 6 min each during each maneuver while sitting, standing, and walking. The average value of VO2 during walking (11.2 +/- 1.7 mL/kg/min) was significantly higher than those for sitting and standing (3.5 +/- 0.4 and 4.3 +/- 0.9 mL/kg/min, respectively; p < 0.001). The HR response during walking was significantly greater than that of either sitting or standing (118 +/- 21vs 70 +/- 10 and 81 +/- 12 beats per minute, respectively: p < 0.001). Persons with paraplegia were able to ambulate efficiently using the powered exoskeleton for overground ambulation, providing potential for functional gain and improved fitness. Clinical trial registration: ClinicalTrials.gov; NCT01454570; "The ReWalk Exoskeletal Walking System for Persons with Paraplegia (VA_ReWalk)"; https://clinicaltrials.gov/ct2/show/NCT01454570.
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Background: Loss of legged mobility due to spinal cord injury (SCI) is associated with multiple physiological and psychological impacts. Powered exoskeletons offer the possibility of regained mobility and reversal or prevention of the secondary effects associated with immobility. Objective: This study was conducted to evaluate mobility outcomes for individuals with SCI after 5 gait-training sessions with a powered exoskeleton, with a primary goal of characterizing the ease of learning and usability of the system. Methods: Sixteen subjects with SCI were enrolled in a pilot clinical trial at Shepherd Center, Atlanta, Georgia, with injury levels ranging from C5 complete to L1 incomplete. An investigational Indego exoskeleton research kit was evaluated for ease of use and efficacy in providing legged mobility. Outcome measures of the study included the 10-meter walk test (10MWT) and the 6-minute walk test (6MWT) as well as measures of independence including donning and doffing times and the ability to walk on various surfaces. Results: At the end of 5 sessions (1.5 hours per session), average walking speed was 0.22 m/s for persons with C5-6 motor complete tetraplegia, 0.26 m/s for T1-8 motor complete paraplegia, and 0.45 m/s for T9-L1 paraplegia. Distances covered in 6 minutes averaged 64 meters for those with C5-6, 74 meters for T1-8, and 121 meters for T9-L1. Additionally, all participants were able to walk on both indoor and outdoor surfaces. Conclusions: Results after only 5 sessions suggest that persons with tetraplegia and paraplegia learn to use the Indego exoskeleton quickly and can manage a variety of surfaces. Walking speeds and distances achieved also indicate that some individuals with paraplegia can quickly become limited community ambulators using this system.
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Passive exoskeletons that assist with human locomotion are often lightweight and compact, but are unable to provide net mechanical power to the exoskeletal wearer. In contrast, powered exoskeletons often provide biologically appropriate levels of mechanical power, but the size and mass of their actuator/power source designs often lead to heavy and unwieldy devices. In this study, we extend the design and evaluation of a lightweight and powerful autonomous exoskeleton evaluated for loaded walking in (J Neuroeng Rehab 11:80, 2014) to the case of unloaded walking conditions. Findings The metabolic energy consumption of seven study participants (85 ± 12 kg body mass) was measured while walking on a level treadmill at 1.4 m/s. Testing conditions included not wearing the exoskeleton and wearing the exoskeleton, in both powered and unpowered modes. When averaged across the gait cycle, the autonomous exoskeleton applied a mean positive mechanical power of 26 ± 1 W (13 W per ankle) with 2.12 kg of added exoskeletal foot-shank mass (1.06 kg per leg). Use of the leg exoskeleton significantly reduced the metabolic cost of walking by 35 ± 13 W, which was an improvement of 10 ± 3% (p = 0.023) relative to the control condition of not wearing the exoskeleton. Conclusions The results of this study highlight the advantages of developing lightweight and powerful exoskeletons that can comfortably assist the body during walking.
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Neuroprosthetic technology and robotic exoskeletons are being developed to facilitate stepping, reduce muscle efforts, and promote motor recovery. Nevertheless, the guidance forces of an exoskeleton may influence the sensory inputs, sensorimotor interactions and resulting muscle activity patterns during stepping. The aim of this study was to report the muscle activation patterns in a sample of intact and injured subjects while walking with a robotic exoskeleton and, in particular, to quantify the level of muscle activity during assisted gait. We recorded electromyographic (EMG) activity of different leg and arm muscles during overground walking in an exoskeleton in six healthy individuals and four spinal cord injury (SCI) participants. In SCI patients, EMG activity of the upper limb muscles was augmented while activation of leg muscles was typically small. Contrary to our expectations, however, in neurologically intact subjects, EMG activity of leg muscles was similar or even larger during exoskeleton-assisted walking compared to normal overground walking. In addition, significant variations in the EMG waveforms were found across different walking conditions. The most variable pattern was observed in the hamstring muscles. Overall, the results are consistent with a non-linear reorganization of the locomotor output when using the robotic stepping devices. The findings may contribute to our understanding of human-machine interactions and adaptation of locomotor activity patterns.
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Background Intensive task specific training early after stroke may enhance beneficial neuroplasticity and functional recovery. Impaired gait after hemiparetic stroke remains a challenge that may be approached early after stroke by use of novel technology. The aim of the study was to investigate the safety and feasibility of the exoskeleton Hybrid Assistive Limb (HAL) for intensive gait training as part of a regular inpatient rehabilitation program for hemiparetic patients with severely impaired gait early after stroke. Methods Eligible were patients until 7 weeks after hemiparetic stroke. Training with HAL was performed 5 days per week by the autonomous and/or the voluntary control mode offered by the system. The study protocol covered safety and feasibility issues and aspects on motor function, gait performance according to the 10 Meter Walking Test (10MWT) and Functional Ambulation Categories (FAC), and activity performance. Results Eight patients completed the study. Median time from stroke to inclusion was 35 days (range 6 to 46). Training started by use of the autonomous HAL mode in all and later switched to the voluntary mode in all but one and required one or two physiotherapists. Number of training sessions ranged from 6 to 31 (median 17) and walking time per session was around 25 minutes. The training was well tolerated and no serious adverse events occurred. All patients improved their walking ability during the training period, as reflected by the 10MWT (from 111.5 to 40 seconds in median) and the FAC (from 0 to 1.5 score in median). Conclusions The HAL system enables intensive training of gait in hemiparetic patients with severely impaired gait function early after stroke. The system is safe when used as part of an inpatient rehabilitation program for these patients by experienced physiotherapists.
Article
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Treadmill training after traumatic SCI has become an established therapy to improve walking capabilities. The hybrid assistive limb (HAL®) exoskeleton has been developed to support motor function and is tailored to the patients´ voluntary drive. To determine whether locomotor training with the exoskeleton HAL® is safe to use and can increase functional mobility in chronic paraplegic patients after SCI. Involved Departments: Dept. of Spinal Cord Injury, Neurology and General and Trauma Surgery at the University Hospital Bergmannsheil Bochum, Germany. A single case experimental A-B (pre-post) design study by repeated assessments of the same patients. The subjects performed 90 days (5 times per week) of HAL® exoskeleton body weight supported treadmill training (BWSTT) with variable gait speed and body weight support. 8 patients with chronic SCI classified by the ASIA Impairment Scale (AIS) consisting of ASIA A (ZPP L3-S1) n=4, ASIA B (with motor ZPP L3-S1) n=1 and ASIA C/D n=3 who received full rehabilitation in the acute and sub acute phase of SCI. Functional measures including treadmill associated walking distance, -speed and time with additional analysis of functional improvements, using the 10-m-walk test (10 MWT), timed-up-and-go test (TUG test), 6-minute-walk test (6 MWT) and the WISCI II score. Secondary physiologic measures including the AIS with the LEMS, the Spinal spasticity (Ashworth Scale) and the lower extremity circumferences. Subjects performed standardized functional testing prior to and after the 90 days of intervention. Highly significant improvements of HAL®-associated walking time, -distance, -and speed. Furthermore significant improvements have been especially shown in the functional abilities without the exoskeleton for over ground walking obtained in the 6MWT, TUG-Test and the 10MWT, including an increase in the WISCI II score of three patients. Muscle strength (LEMS) increased in all patients accompanied by a gain of the lower limb circumferences. A conversion in the AIS was ascertained in one patient (ASIA B to ASIA C). One patient reported a decrease of spinal spasticity. HAL® exoskeleton training results in improved over ground walking and leads to the assumption of a beneficial effect on ambulatory mobility. However evaluation in larger clinical trials is required.
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Objective: Cerebral palsy (CP) is a disabling condition characterized by the motor impairment, which is difficult to be ameliorated. In the brain of infants with CP, there are persistent pathomechanisms including accentuated neuroinflammation. Since erythropoietin was demonstrated to have neuroprotective effect via anti-inflammatory and anti-apoptotic properties, we hypothesized that the administration of recombinant human EPO (rhEPO) could help children with CP, especially young infants. Materials and method: We investigated the therapeutic efficacy of rhEPO for infants with CP, who had been undergoing active rehabilitation in hospitalized setting to eliminate treatment bias. Twenty infants with CP were randomly divided into EPO or control group equally. We compared the changes in the Gross Motor Function Measure (GMFM) and the Bayley Scales of Infant Development-II (BSID-II) scores during one month of hospitalization between two groups. Results: The improvements after 1 month on the GMFM A and GMFM total scores differed significantly between the groups (p = 0.003, p = 0.04, respectively). However, the changes after 6 months were not different between the two groups. The scores of BSID-II did not show any differences at 1-month and 6-months post-treatment. Conclusion: These results indicated that rhEPO could have therapeutic efficacy for infants with CP during the active rehabilitation and anti-inflammation was suggested to be one of its therapeutic mechanisms.
Article
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Efforts have recently been reported by several research groups on the development of computer-controlled lower limb orthoses to enable legged locomotion in persons with paraplegia. Such systems must employ a control framework that provides essential movements to the paraplegic user (i.e., sitting, standing, and walking), and ideally enable the user to autonomously command these various movements in a safe, reliable, and intuitive manner. This paper describes a control method that enables a paraplegic user to perform sitting, standing, and walking movements, which are commanded based on postural information measured by the device. The proposed user interface and control structure was implemented on a powered lower limb orthosis, and the system was tested on a paraplegic subject with a T10 complete injury. Experimental data is presented that indicates the ability of the proposed control architecture to provide appropriate user-initiated control of sitting, standing, and walking. The authors also provide a link to a video that qualitatively demonstrates the user's ability to independently control basic movements via the proposed control method.
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The objective of the study was to evaluate the safety and tolerance of use of the ReWalk™ exoskeleton ambulation system in people with spinal cord injury. Measures of functional ambulation were also assessed and correlated to neurological spinal cord level, age, and duration since injury. Case series observational study. A national spinal cord injury centre. Six volunteer participants were recruited from the follow-up outpatient clinic. Safety was assessed with regard to falls, status of the skin, status of the spine and joints, blood pressure, pulse, and electrocardiography (ECG). Pain and fatigue were graded by the participants using a visual analogue scale pre- and post-training. Participants completed a 10-statement questionnaire regarding safety, comfort, and secondary medical effects. After being able to walk 100 m, timed up and go, distance walked in 6 minutes and 10-m timed walk were measured. There were no adverse safety events. Use of the system was generally well tolerated, with no increase in pain and a moderate level of fatigue after use. Individuals with lower level of spinal cord injury performed walking more efficiently. Volunteer participants were able to ambulate with the ReWalk™ for a distance of 100 m, with no adverse effects during the course of an average of 13-14 training sessions. The participants were generally positive regarding the use of the system.
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Mobility options for persons suffering from paraplegia or paraparesis are limited to mainly wheeled devices. There are significant health, psychological, and social consequences related to being confined to a wheelchair. We present the Mina, a robotic orthosis for assisting mobility, which offers a legged mobility option for these persons. Mina is an overground robotic device that is worn on the back and around the legs to provide mobility assistance for people suffering from paraplegia or paraparesis. Mina uses compliant actuation to power the hip and knee joints. For paralyzed users, balance is provided with the assistance of forearm crutches. This paper presents the evaluation of Mina with two paraplegics (SCI ASIA-A). We confirmed that with a few hours of training and practice, Mina is currently able to provide paraplegics walking mobility at speeds of up to 0.20 m/s. We further confirmed that using Mina is not physically taxing and requires little cognitive effort, allowing the user to converse and maintain eye contact while walking.
Article
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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. The orthosis has a mass of 12 kg and is capable of providing maximum joint torques of 40 Nm with hip and knee joint ranges of motion from 105° flexion to 30° extension and 105° flexion to 10° hyperextension, respectively. A custom distributed embedded system controls the orthosis with power being provided by a lithium polymer battery which provides power for one hour of continuous walking. In order to demonstrate the ability of the orthosis to assist walking, the orthosis was experimentally implemented on a paraplegic subject with a T10 complete injury. Data collected during walking indicates a high degree of step-to-step repeatability of hip and knee trajectories (as enforced by the orthosis) and an average walking speed of 0.8 km/hr. The electrical power required at each hip and knee joint during gait was approximately 25 and 27 W, respectively, contributing to the 117 W overall electrical power required by the device during walking. A video of walking corresponding to the aforementioned data is included in the supplemental material.
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A neurobot (NR) is a mechatronic wearable robot that can be applied to drive a paralyzed limb. Through the application of controllable forces, a NR can assist, replace, or retrain a certain motor function. Robotic intervention in rehabilitation of motor disorders has a potential to improve traditional therapeutic interventions. Because of its flexibility, repeatability and quantifiability, NRs have been more and more applied in neurorehabilitation. Furthermore, combination of NRs with functional electrical stimulation/therapy constitutes a trend to overcome a number of practical limitations to widespread the application of NRs in clinical settings and motor control studies. In this review, we examine the motor learning principles, robotic control approaches and novel developments from studies with NRs and hybrid systems, with a focus on rehabilitation of the lower limbs.
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For over a century, technologists and scientists have actively sought the development of exoskeletons and orthoses designed to augment human economy, strength, and endurance. While there are still many challenges associated with exoskeletal and orthotic design that have yet to be perfected, the advances in the field have been truly impressive. In this commentary, I first classify exoskeletons and orthoses into devices that act in series and in parallel to a human limb, providing a few examples within each category. This classification is then followed by a discussion of major design challenges and future research directions critical to the field of exoskeletons and orthoses.
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We undertook this investigation to determine the interrater reliability of manual tests of elbow flexor muscle spasticity graded on a modified Ashworth scale. We each independently graded the elbow flexor muscle spasticity of 30 patients with intracranial lesions. We agreed on 86.7% of our ratings. The Kendall's tau correlation between our grades was .847 (p less than .001). Thus, the relationship between the raters' judgments was significant and the reliability was good. Although the results were limited to the elbow flexor muscle group, we believe them to be positive enough to encourage further trials of the modified Ashworth scale for grading spasticity.
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This article presents the state of the art in passive devices for enhancing limb movement in people with neuromuscular disabilities. Both upper- and lower-limb projects and devices are described. Special emphasis is placed on a passive functional upper-limb orthosis called the Wilmington Robotic Exoskeleton (WREX). The development and testing of the WREX with children with limited arm strength are described. The exoskeleton has two links and 4 degrees of freedom. It uses linear elastic elements that balance the effects of gravity in three dimensions. The experiences of five children with arthrogryposis who used the WREX are described.
Chapter
Rehabilitation robots have become an important tool in stroke rehabilitation. Compared to manual arm therapy, robot-supported arm therapy can be more intensive, with more frequent, more numerous, and longer repetitions. Therefore, robots have the potential to improve the rehabilitation process in stroke patients. In this chapter, the three-dimensional, multi-degree-of-freedom ARMin arm robot is presented. The device has an exoskeleton structure that enables the training of activities of daily living. Patient-responsive control strategies assist the patient only as much as needed and stimulate patient activity. This chapter covers the mechanical setup, the therapy modes, and the clinical evaluation of the ARMin robot. It concludes with an outlook on technical developments and about the technology transfer to industry.
Chapter
Treadmill training after traumatic spinal cord injury is established as a therapy to improve walking capabilities in incomplete injured patients. In this study we investigate walking capabilities after a three month period of HAL® exoskeleton supported treadmill training in patients with chronic (>6 month) complete/incomplete (ASIA A – ASIA C) spinal cord injury. We monitored walking distance, walking speed and walking time with additional analysis of functional improvement by using the 10-m-walk test, the timed-up-and-go test and the WISCI II score in combination with the ASIA classification.
Article
It is a single case study. An investigation to what extent the quality of life (QoL) of patients with spinal cord injury can be influenced by the training with an exoskeleton. The study was carried out at a Hospital for neurological rehabilitation, Germany. One patient (male, 22 years), initially unable to walk independently after traumatic spinal cord injury with neurological level Th11 (ASIA Impairment Scale C) was recruited for this study 1 year after injury. The progress of the first 6 months of ReWalk training was documented and as primary outcome measure the QoL was measured with SF-36 questionnaire. Secondary outcome measures were ASIA scale, Berg-Balance-Scale and Dynamic Gait Index. At the end of the studyperiod the patient was able to walk independently supervised by one person. QoL, mobility, risk of falling, motor skills and control of bladder and bowel functions were improved. A positive effect of robot-assisted gait training on various areas of the QoL was shown. Subsequent studies should aim to verify this effect through a higher number of patients and to different injury levels.
Chapter
Rehabilitation robots have become an important tool in stroke rehabilitation. Compared to manual arm therapy, robot-supported arm therapy can be more intensive, of longer duration, and more repetitive. Therefore, robots have the potential to improve the rehabilitation process in stroke patients. In this chapter, the three-dimensional, multi-degree-of-freedom ARMin arm robot is presented. The device has an exoskeleton structure that enables the training of activities of daily living. Patient-responsive control strategies assist the patient only as much as needed and stimulate patient activity. This chapter covers the mechanical setup, the therapy modes, and the clinical evaluation of the ARMin robot. It concludes with an outlook on technical developments and about the technology transfer to industry.
Article
To assess the feasibility of conducting a well-powered trial evaluating the neurological and functional effects of using an exoskeleton in individuals with chronic spinal cord injury. A longitudinal, prospective, self-controlled feasibility study. Specialist Spinal Cord Injuries Centre, UK; 8 months during 2013-2014. Individuals with chronic motor complete or incomplete spinal cord injury. Enrolled subjects were assigned to 20 exoskeleton (ReWalk™, Argo Medical Technologies Ltd, Yokneam Ilit, Israel) training sessions over a 10-week training period. Feasibility measures, clinical and mobility outcome measures and measures appraising subjects' disability and attitude towards assistive technology were assessed before, during and after the study. Descriptive statistics were applied. Out of 60 candidates, ten (17%) were enrolled and five (8%) completed the training programme. Primary reasons for not enrolling were ineligibility (n = 24, 40%) and limited interest to engage in a 10-week training programme (n = 16, 27%). Five out of ten enrolled subjects experienced grade I/II skin aberrations. While walking speeds were higher and walking distances were longer in all exoskeleton users when compared with non-use, the exoskeleton did generally not meet subjects' high expectations in terms of perceived benefits. The conduct of a controlled trial evaluating the benefits of using exoskeletons that require a lengthy user-commitment to training of individuals with chronic motor complete or incomplete spinal cord injury comes with considerable feasibility challenges. Vigilance is required for preventing and detecting medical complications in spinal cord injury exoskeleton users. © The Author(s) 2015.
Article
Objective: Evaluate feasibility and safety of EksoTM to aid ambulation in individuals with SCI. Design: Prospective pilot study. Setting: SCI Rehabilitation Center Outpatient Gym. Participants: Eight individuals, at least 18 years of age, with complete T1 SCI or below, within 2 years of injury, completed initial inpatient rehabilitation. All participants signed informed consent, had been cleared from requiring spinal orthoses, met inclusion criteria, and were pre-screened based on device requirements and medical stability. Intervention: Six weekly sessions with graduated time and less assistance in the EksoTM device. Outcome Measures: Skin evaluation, blood pressure, pain level, spasticity, time and level of assistance needed to transfer into and donn device; time ambulating; time up in device; assistive devices used during ambulation; step length; distance walked; level of assistance during use; and level of assistance needed to doff and transfer out of device. Results: No major skin effects, minimal pain reports, no known fractures, swelling, or other adverse events. Level of assistance ranged from dependent to moderate independent, average set up time was 18.13 minutes, loss of balance and falls were infrequent. Conclusions: Bionic exoskeletons such as EksoTM are safe for those with complete thoracic SCI in a controlled environment, in the presence of experts, and may eventually enhance mobility in those without volitional lower extremity function. There appears to be a training effect in the device but further trials are needed. Future studies of bionic exoskeletons as gait training devices are warranted. Future studies of bionic exoskeletons as a clinical tool to alleviate secondary complications should be considered.
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.
Article
Objective To compare the efficacy of gait training using a single-leg version of the hybrid assistive limb (HAL) on the paretic side to conventional gait training in individuals with subacute stroke. Design Randomized open controlled pilot trial Setting Hospitalized care in a recovery phase rehabilitation ward Participants Convenience sample. Of 44 patients who met the criteria for this study, 12 patients refused. After randomization, 10 patients withdrew and a total of 22 poststroke participants (HAL group: n = 11, conventional group: n = 11) completed the randomized clinical trial. Interventions All participants received twelve 20-minute sessions in 4 weeks of either HAL (wearing the single-leg version of HAL on their paretic side) or conventional (performed by skilled and experienced physical therapists) gait training. Main Outcome Measures Outcome measures were evaluated prior to training and after 12 sessions. Functional Ambulation Category (FAC) was the primary outcome measure, while secondary outcome measures included maximum walking speed, timed up-and-go test, 6-minute walk distance, Short Physical Performance Battery, Fugl-Meyer assessment of lower extremity, and isometric muscle strength (hip flexion and extension, knee flexion and extension). Results No participants withdrew due to adverse effects. Participants who received gait training with HAL showed significantly more improvement in FAC than those who received conventional gait training (95% Confidence Interval, 0.02-0.88; P = .04). Secondary measures did not differ between the 2 groups. Conclusions The results obtained in this randomized controlled trial suggest that a gait training program with HAL could improve independent walking more efficiently than conventional gait training.
Article
Stroke is the leading cause of adult disability, with walking impairment being a devastating indicator of chronic post-stroke hemiparesis. Limited resources exist for individual treatments; therefore, the delivery of safe group exercise therapy is highly desired. To examine whether the application of group-based motor imagery practice to community-dwelling individuals with chronic hemiparesis improves gait. Sixteen individuals with chronic hemiparesis from two community centers participated in the study, with eight from each center. Four participants in each center received five weeks of the experimental intervention, consisting of group-based motor imagery exercises of gait tasks, followed by five weeks of control treatment of motor imagery exercises for the affected upper extremity. Four other subjects in each center received the same treatments in reverse order. Pre- and post intervention measurements included clinical and biomechanical gait parameters. Comparisons within (pre- vs. post) and between treatments (experimental vs. control) indicated no significant change in any gait variable. Nevertheless, the verbal reports of most participants alluded to satisfaction with the intervention and to an increase in self-confidence. Despite the lack of evidence for the effectiveness of group-based motor imagery practice in improving gait among individuals with chronic hemiparesis, the contrast between the measured negative outcomes and the positive verbal reports merits further inquiry.
Article
The aim of this study was to assess the safety and performance of ReWalk in enabling people with paraplegia due to spinal cord injury to carry out routine ambulatory functions. This was an open, noncomparative, nonrandomized study of the safety and performance of the ReWalk powered exoskeleton. All 12 subjects have completed the active intervention; three remain in long-term follow-up. After training, all subjects were able to independently transfer and walk, without human assistance while using the ReWalk, for at least 50 to 100 m continuously, for a period of at least 5 to 10 mins continuously and with velocities ranging from 0.03 to 0.45 m/sec (mean, 0.25 m/sec). Excluding two subjects with considerably reduced walking abilities, average distances and velocities improved significantly. Some subjects reported improvements in pain, bowel and bladder function, and spasticity during the trial. All subjects had strong positive comments regarding the emotional/psychosocial benefits of the use of ReWalk. ReWalk holds considerable potential as a safe ambulatory powered orthosis for motor-complete thoracic-level spinal cord injury patients. Most subjects achieved a level of walking proficiency close to that needed for limited community ambulation. A high degree of performance variability was observed across individuals. Some of this variability was explained by level of injury, but other factors have not been completely identified. Further development and application of this rehabilitation tool to other diagnoses are expected in the future.
Article
In order to widen the potentialities of manipulation of the Laboratoire de Mcanique des solides (LMS) mechanical hand, we developed a new planning approach based on the use of a specific exoskeleton. This one has kinematics architecture and dimensions identical to the mechanical hand. This feature allows us to obtain manipulation trajectories for the mechanical hand, very easily and very quickly, by using the exoskeleton, without complex calibration. Manipulation's trajectories are replayed offline with an autonomous control, and, consequently, the exoskeleton is not used with any feedback strategy for telemanipulation. This paper presents the characteristics of this exoskeleton and the graphic interface that we developed. This one uses a method to determine the object's evolution during the manipulation with the exoskeleton, without using exteroceptive sensors. This new approach was tested for standard trajectories by simulation on a Computer-aided design (CAD) robotics system and by using the mechanical hand. Thus, we validate the use concept of an isomorphic exoskeleton to mechanical hand for manipulation planning with the LMS mechanical hand.
Article
Traditional physical therapy is beneficial in restoring mobility in individuals who have sustained spinal cord injury (SCI), but residual limitations often persist. Robotic technologies may offer opportunities for further gains. The purpose of this case study was to document the use and practicality of gait training for an individual with chronic, incomplete SCI with asymmetric lower limb motor deficits using a novel robotic knee orthosis (RKO). The participant was a 22-year-old woman who sustained fractures of the odontoid process and C5-C6 vertebrae from a motor vehicle accident resulting in incomplete SCI with asymmetric tetraparesis, right side more severe than left side. She required supervised assistance with gait and balance tasks, minimal assistance to ascend/descend steps using a handrail, and upper extremity assistance for sit-to-stand tasks. The participant underwent 7 one-hour sessions of mobility training, using a novel RKO. Her primary goal was to increase independence and endurance with mobility. Functional measures included the 6-Minute Walk Test, the Berg Balance Scale, the Timed Up & Go Test, and the 10-Meter Walk Test. Outcomes were assessed and recorded at baseline and on completion of 7 hours of training with the device over a 2-week period. No adverse events occurred. The RKO was well received by both the participant and the treating therapist. The participant demonstrated improvements in the 6-Minute Walk Test and Berg Balance Scale after RKO-training intervention. Outcomes suggest that the use of this device during a physical therapy program for an individual with incomplete SCI is practical and this device may be a useful adjunct to standard training.
Article
A walking assistance device using a flexible shaft was developed. The combination of a flexible shaft with a worm gear was successfully adopted on this device to simplify its appearance and reduce its size. A hybrid - control system on this device controls both torque and angle at the ankle and knee joints. In this system, the torsional spring constant of the flexible shaft is taken into account by the motor in controlling the power and angle of rotation of the motor. To expand the area in which a person may use the device, it is equipped with a self-contained system powered by a Lithium-ion battery and controlled by an SH-4 microcomputer and actuators, consisting of motors and gears, all of which are carried in a small backpack. Consequently, persons using the device may walk freely in both indoor and outdoor environments.
Conference Paper
Current advancements in exoskeleton robotics allow those with mobility disorders to walk again. The user conveys his or her desired motion to the exoskeleton using a Human Machine Interface (HMI). This allows the users to stand up, walk, and sit down independently. Existing HMIs require unnatural motions that inhibit the gait. The HMI developed here uses natural gestures while ensuring the safety of the user. This method utilizes a unique sensor suite and a finite state automaton to allow a spinal cord injury patient to easily use an exoskeleton for mobility.
Article
Our goal is to enhance the quality of life of patients with hemiplegia by means of an active motion support system that assists the impaired motion such as to make it as close as possible to the motion of an able bodied person. We have developed the Robot Suit HAL (Hybrid Assistive Limb) to actively support and enhance the human motor functions. The purpose of the research presented in this paper is to propose the required control method to support voluntarily motion using a trigger based on patient's bioelectrical signal. Clinical trials were conducted in order to investigate the effectiveness of the proposed control method. The first stage of the trials, described in this paper, involved the participation of one hemiplegic patient who is not able to bend his right knee. As a result, the motion support provided by the HAL moved the paralyzed knee joint according to his intention and improved the range of the subject's knee flexion. The first evaluation of the control method with one subject showed promising results for future trials to explore the effectiveness for a wide range of types of hemiplegia.
Article
To guide development of robotic lower limb exoskeletons, it is necessary to understand how humans adapt to powered assistance. The purposes of this study were to quantify joint moments while healthy subjects adapted to a robotic ankle exoskeleton and to determine if the period of motor adaptation is dependent on the magnitude of robotic assistance. The pneumatically powered ankle exoskeleton provided plantar flexor torque controlled by the wearer's soleus electromyography (EMG). Eleven naïve individuals completed two 30-min sessions walking on a split-belt instrumented treadmill at 1.25m/s while wearing the ankle exoskeleton. After two sessions of practice, subjects reduced their soleus EMG activation by approximately 36% and walked with total ankle moment patterns similar to their unassisted gait (r(2)=0.98+/-0.02, THSD, p>0.05). They had substantially different ankle kinematic patterns compared to their unassisted gait (r(2)=0.79+/-0.12, THSD, p<0.05). Not all of the subjects reached a steady-state gait pattern within the two sessions, in contrast to a previous study using a weaker robotic ankle exoskeleton (Gordon and Ferris, 2007). Our results strongly suggest that humans aim for similar joint moment patterns when walking with robotic assistance rather than similar kinematic patterns. In addition, greater robotic assistance provided during initial use results in a longer adaptation process than lesser robotic assistance.
Conference Paper
This paper proposes an algorithm to estimate human intentions during walking. Not only walk start or stop but walking cycle is considered as the intentions in this paper. The algorithm is embedded into a walking support system, a wearable robot "Robot Suit HAL-3", for paraplegia patients. The estimation of patients' intentions is indispensable for effective and comfortable motion support, but the biological signals such as myoelectricity which is used for the support by HAL-3 cannot be measured properly. The proposed algorithm, therefore, estimates patients' intentions from other channels such as a floor reaction force and a body posture. The effectiveness of this algorithm is investigated through experiments with two types of patients. One has a sensory paralysis on both legs, especially a left leg has severe trouble. The other has troubles in sensory and motor ability on both legs. We show HAL-3 supports patients' walk comfortably, estimating patient intentions.
Article
In the nearly six decades since researchers began to explore methods of creating them, exoskeletons have progressed from the stuff of science fiction to nearly commercialized products. While there are still many challenges associated with exoskeleton development that have yet to be perfected, the advances in the field have been enormous. In this paper, we review the history and discuss the state-of-the-art of lower limb exoskeletons and active orthoses. We provide a design overview of hardware, actuation, sensory, and control systems for most of the devices that have been described in the literature, and end with a discussion of the major advances that have been made and hurdles yet to be overcome.
Maratona di Roma 2015, un esoscheletro hi-tech per tornare a correre
  • Fondazione Santa
Fondazione Santa Lucia. 2015. Maratona di Roma 2015, un esoscheletro hi-tech per tornare a correre. Retrieved from http://www.hsantalucia.it/modules.php?name=Newsandfile=articlean dsid=989
Gait training early after stroke with a new exoskeleton-the hybrid assistive limb: a study of safety and feasibility
  • A Nilsson
  • K S Vreede
  • V Haglund
  • H Kawamoto
  • Y Sankai
  • J Borg
Nilsson, A., Vreede, K. S., Haglund, V., Kawamoto, H., Sankai, Y., and Borg, J. 2014. Gait training early after stroke with a new exoskeleton-the hybrid assistive limb: a study of safety and feasibility. Journal of Neuroengineering and Rehabilitation, 11(92), 1-10. doi:10.1186/1743-0003-11-92
Exoskeletal-assisted walking for persons with motor-complete paraplegia
  • A M Spungen
  • P Asselin
  • D B Fineberg
  • S D Kornfeld
  • N Y Harel
Spungen, A. M., Asselin, P., Fineberg, D. B., Kornfeld, S. D., and Harel, N. Y. 2013, Apr 15-17. Exoskeletal-assisted walking for persons with motor-complete paraplegia. Paper presented at the STO Human Factors and Medicine Panel (HFM) Symposium, Milan, IT.
Gait training with a robotic leg brace after stroke:A randomized controlled pilot study
  • J Stein
  • L Bishop
  • D J Stein
  • C K Wong
Stein, J., Bishop, L., Stein, D. J., and Wong, C. K. 2014. Gait training with a robotic leg brace after stroke:A randomized controlled pilot study. American Journal of Physical Medicine and Rehabilitation, 93(11), 987-994. doi:10.1097/PHM.0000000000000119
Differentiating ability in users of the ReWalkTM powered exoskeleton: An analysis of walking kinematics
  • M Talaty
  • A Esquenazi
  • J E Briceño
Talaty, M., Esquenazi, A., and Briceño, J. E. 2013. Differentiating ability in users of the ReWalkTM powered exoskeleton: An analysis of walking kinematics. Paper presented at the IEEE International Conference on Rehabilitation Robotics: ICORR 2013, Seattle, WA. doi:10.1109/ ICORR.2013.6650469
Assistive Products for Persons with Disability-Classification and Terminology
  • Iso
ISO. 2016. ISO 9999:2016 Assistive Products for Persons with Disability-Classification and Terminology, 6th edition. Brussels, BE: CEN.