Edwin van Asseldonk

Edwin van Asseldonk
University of Twente | UT · Department of Biomechanical Engineering

PhD

About

164
Publications
41,773
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5,257
Citations
Additional affiliations
June 2002 - present
University of Twente
Position
  • Professor (Assistant)

Publications

Publications (164)
Preprint
Walking very slowly increases the time spent in the double support phase, which could be resembled by the staggered stance posture. Maintaining balance in this posture is important in order to continue walking safely. We therefore aimed to increase the understanding of balance recovery in staggered stance. We studied balance responses on joint- and...
Article
Interaction control can take opportunities offered by contact robots physically interacting with their human user, such as assistance targeted to each human user, communication of goals to enable effective teamwork, and task-directed motion resistance in physical training and rehabilitation contexts. Here we review the burgeoning field of interacti...
Article
Healthy individuals highly regulate their whole body angular momentum (WBAM) during walking. Since WBAM regulation is essential in maintaining balance, a better understanding is required on how healthy individuals recover from WBAM perturbations. We therefore studied how healthy individuals recover WBAM in the sagittal plane. WBAM can be regulated...
Article
Knowledge on joint impedance during walking in various conditions is relevant for clinical decision-making and the development of robotic gait trainers, leg prostheses, leg orthotics and wearable exoskeletons. Whereas ankle impedance during walking has been experimentally assessed, knee and hip joint impedance during walking have not been identifie...
Article
Full-text available
Muscle synergy theory assumes that the central nervous system generates a wide range of complex motor outputs by recruiting muscle synergies with different strengths and timings. The current understanding is that a common set of muscle synergies underlies unperturbed as well as perturbed walking at self-selected speeds. However, it is not known whe...
Article
Full-text available
Background In the last two decades, lower-limb exoskeletons have been developed to assist human standing and locomotion. One of the ongoing challenges is the cooperation between the exoskeleton balance support and the wearer control. Here we present a cooperative ankle-exoskeleton control strategy to assist in balance recovery after unexpected dist...
Preprint
Background: Ankle-foot orthoses (AFOs) are extensively used as a primary management method to assist walking and ambulation of children with Cerebral Palsy (CP). However, there are certain barriers that hinder their prescription and as well as their use as a mobility device in all kinds of daily-life activities. This research attempts to further un...
Preprint
During locomotion, legged robots interact with the ground by sequentially establishing and breaking contact. The interaction wrenches that arise from contact are used to steer the robot's Center of Mass (CoM) and reject perturbations that make the system deviate from the desired trajectory and often make them fall. The feasibility of a given contro...
Preprint
Series elastic actuators (SEA) with their inherent compliance offer a safe torque source for robots that are interacting with various environments, including humans. These applications have high requirements for the SEA torque controllers, both in the torque response as well as interaction behavior with its the environment. To differentiate state o...
Chapter
In the last two decades, lower-limb exoskeletons have been developed to assist human standing and locomotion. One of the ongoing challenges is still balance support. Here we present a control strategy for an ankle-exoskeleton to assist balance recovery after unexpected disturbances during walking. We evaluated the controller in two healthy particip...
Chapter
Controlling wearable exoskeletons to interact with people suffering from locomotion disabilities due to lesions of the central nervous system is a complex challenge since it entails fulfillment of many concurrent objectives: versatility in different applications (assistance and rehabilitation), user-specific adaptation to residual motor functions,...
Chapter
Robot-assisted gait training (RAGT) is a promising rehabilitation technique that is increasingly used in the clinic to improve walking ability after a neurological disorder. The effectiveness of RAGT might depend on the customization of the robotic therapy, which in most of the cases is done either manually by the clinical practitioner (MT) or by a...
Chapter
Joint impedance plays an important role in postural control and movement. However, current experimental knowledge on lower limb impedance during gait is limited to the ankle joint. We designed the LOwer limb PERturbator (LOPER) aimed to assess knee and hip joint impedance during gait. The LOPER applies force perturbations with a 39 Hz bandwidth, te...
Article
Full-text available
Recent advances in the control of overground exoskeletons are being centered on improving balance support and decreasing the reliance on crutches. However, appropriate methods to quantify the stability of these exoskeletons (and their users) are still under development. A reliable and reproducible balance assessment is critical to enrich exoskeleto...
Preprint
Full-text available
Knowledge on joint impedance during walking in various conditions is relevant for clinical decision making and the development of robotic gait trainers, leg prostheses, leg orthotics, and wearable exoskeletons. Whereas ankle impedance during walking has been experimentally assessed, knee and hip joint impedance during walking have not been identifi...
Article
Full-text available
Active prosthetic and orthotic devices have the potential to increase quality of life for individuals with impaired mobility. However, more research into human-like control methods is needed to create seamless interaction between device and user. In forward simulations the reflex-based neuromuscular model (RNM) by Song and Geyer shows promising sim...
Article
Avatar personalization may contribute to the engagement in a video game. This exploratory study investigated which features a 3D virtual avatar should have for the user to experience Body Ownership. 10 participants (aged 20 to 30) participated in this study. For each participant three avatars were created based on a single picture of them from the...
Article
Full-text available
People with spasticity, i.e., stretch hyperreflexia, have a limited functional independence and mobility. While a broad range of spasticity treatments is available, many treatments are invasive, non-specific, or temporary and might have negative side effects. Operant conditioning of the stretch reflex is a promising non-invasive paradigm with poten...
Chapter
Full-text available
Avances recientes en el control de exoesqueletos se están centrando en mejorar la asistencia de equilibrio y disminuir la dependencia de las muletas. Sin embargo, métodos apropiados para cuantificar la estabilidad de estos exoesqueletos (y de sus usuarios) aún son escasos. Una evaluación del equilibrio cuantitativa es fundamental para enriquecer el...
Article
Motorized assessment of the stretch reflex is instrumental to gain understanding of the stretch reflex, its physiological origin and to differentiate effects of neurological disorders, like spasticity. Both short-latency (M1) and medium-latency (M2) stretch reflexes have been reported to depend on the velocity and acceleration of an applied ramp-an...
Article
Centre of mass (CoM) motion during human balance recovery is largely influenced by the ground reaction force (GRF) and the centre of pressure (CoP). During gait, foot placement creates a region of possible CoP locations in the following double support (DS). This study aims to increase insight into how humans modulate the CoP during DS, and which Co...
Preprint
Full-text available
Background In the last two decades, lower-limb exoskeletons have been developed to assist human standing and locomotion. One of the ongoing challenges is the cooperation between the exoskeleton balance support and the wearer control. Here we present a cooperative ankle-exoskeleton control strategy to assist in balance recovery after unexpected dist...
Article
Full-text available
Background People with brain or neural injuries, such as cerebral palsy or spinal cord injury, commonly have joint hyper-resistance. Diagnosis and treatment of joint hyper-resistance is challenging due to a mix of tonic and phasic contributions. The parallel-cascade (PC) system identification technique offers a potential solution to disentangle the...
Article
Full-text available
Background: Regaining gait capacity is an important rehabilitation goal post stroke. Compared to clinically available robotic gait trainers, robots with an assist-as-needed approach and multiple degrees of freedom (AANmDOF) are expected to support motor learning, and might improve the post-stroke gait pattern. However, their benefits compared to c...
Article
Full-text available
In this paper, we present the design, control, and preliminary evaluation of the Symbitron exoskeleton, a lower limb modular exoskeleton developed for people with a spinal cord injury. The mechanical and electrical configuration and the controller can be personalized to accommodate differences in impairments among individuals with spinal cord injur...
Article
Full-text available
Haptic interaction between two humans, for example, a physiotherapist assisting a patient regaining the ability to grasp a cup, likely facilitates motor skill acquisition. Haptic human–human interaction has been shown to enhance individual performance improvement in a tracking task with a visuomotor rotation perturbation. These results are remarkab...
Article
Full-text available
Background Recently developed controllers for robot-assisted gait training allow for the adjustment of assistance for specific subtasks (i.e. specific joints and intervals of the gait cycle that are related to common impairments after stroke). However, not much is known about possible interactions between subtasks and a better understanding of this...
Article
Powered exoskeletons (EXOs) have emerged as potential devices for Spinal Cord Injury (SCI) to support the intervention of physical therapists during therapy (rehabilitation EXOs) as well as to assist lower limb motion during the daily life (assistive EXOs). Although the ankle is considered a key joint for gait restoration after SCI, very few ankle...
Article
Full-text available
Background: People use various strategies to maintain balance, such as taking a reactive step or rotating the upper body. To gain insight in human balance control, it is useful to know what makes people switch from one strategy to another. In previous studies the transition from a non-stepping balance response to reactive stepping was often descri...
Preprint
Full-text available
Haptic interaction between two humans, for example, parents physically supporting their child while it learns to keep balance on a bicycle, likely facilitates motor skill acquisition. Haptic human-human interaction has been shown to enhance individual motor improvement in a tracking task with a visuomotor rotation perturbation. These results are re...
Article
Mechanical impedance, which changes with posture and muscle activations, characterizes how the central nervous system regulates the interaction with the environment. Traditional approaches to impedance estimation, based on averaging of movement kinetics, requires a large number of trials and may introduce bias to the estimation due to the high vari...
Article
Human-like balance controllers are desired for wearable exoskeletons in order to enhance human-robot interaction. Momentum-based controllers (MBC) have been successfully applied in bipeds, however, it is unknown to what degree they are able to mimic human balance responses. In this paper, we investigated the ability of an MBC to generate humanlike...
Article
Full-text available
Trans-spinal direct current stimulation (tsDCS) provides a non-invasive, clinically viable approach to potentially restore physiological neuromuscular function after neurological impairment, e.g., spinal cord injury (SCI). Use of tsDCS has been hampered by the inability of delivering stimulation patterns based on the activity of neural targets resp...
Article
Powered exoskeletons are among the emerging technologies claiming to assist functional ambulation. The potential to adapt robotic assistance based on specific motor abilities of incomplete spinal cord injury (iSCI) subjects, is crucial to optimize Human-Robot Interaction (HRI). Achilles, an autonomous wearable robot able to assist ankle during walk...
Article
Full-text available
Background: In clinical practice, therapists choose the amount of assistance for robot-assisted training. This can result in outcomes that are influenced by subjective decisions and tuning of training parameters can be time-consuming. Therefore, various algorithms to automatically tune the assistance have been developed. However, the assistance ap...
Article
Full-text available
Objective To explore user-centered design methods currently implemented during development of lower limb wearable robots and how they are utilized during different stages of product development. Background Currently, there appears to be a lack of standardized frameworks for evaluation methods and design requirements to implement effective user-cen...
Chapter
The main purpose of this study was to identify outcome measures that developers working in the area of wearable robots utilize during different phases of product development. Experts in the field were invited to complete a short, anonymous, online survey. The results presented in this study focus on answers that engineers working on exoskeletons fo...
Article
Full-text available
Human walking speeds can be influenced by multiple factors, from energetic considerations to the time to reach a destination. Neurological deficits or lower-limb injuries can lead to slower walking speeds, and the recovery of able-bodied gait speed and behavior from impaired gait is considered an important rehabilitation goal. Because gait studies...
Article
Full-text available
The amount of research on developing exoskeletons for human gait assistance has been growing in the recent years. However, the control design of exoskeletons for assisting human walking remains unclear. This paper presents a novel bio-inspired reflex-based control for assisting human walking. In this approach, the leg force is used as a feedback si...
Article
Full-text available
Background Recovery of walking is a primary rehabilitation goal of most stroke survivors. Control of pelvic movements is one of the essential determinants of gait, yet surprisingly, conventional robot-assisted gait trainers constrain pelvic movements. Novel robot-assisted gait trainers, such as LOPES II, are able to support pelvic movements during...
Article
The ankle joint muscles can contribute to balance during walking by modulating the center of pressure and ground reaction forces through an ankle moment. This is especially effective in the sagittal plane through ankle plantar- or dorsiflexion. If the ankle joints were to be physically blocked to make an ankle strategy ineffective, there would be n...
Article
Full-text available
Previous research found reduced motor chunking behavior in older adults compared to young adults. However, it remains unclear whether older adults are unable to use a chunking strategy or whether they are just slower in developing them. Our goal was to investigate the effect of extended practice on the development of chunking behavior in healthy ol...
Article
Trans-spinal Direct Current Stimulation (tsDCS) is a technique considered for the treatment of corticospinal damage or dysfunction. TsDCS aims to induce functional modulation in the corticospinal circuitry via a direct current (DC) generated electric field. To ensure subject safety, subjects with metallic implants are generally excluded from receiv...
Article
Full-text available
This paper presents an experimental study on balance recovery control with a lower limb exoskeleton robot. Four participants were subjected to a perturbation during standing, a forward force impulse applied to their pelvis that forced them to step forward with the right leg for balance recovery. Trials with and without exoskeleton assistance to mov...
Chapter
Improving stability of people wearing a lower extremity Wearable Exoskeleton (WE) is one of the biggest challenges in the field. The goal of this preliminary study was to improve balance recovery from perturbations in people with incomplete Spinal Cord Injury (SCI) assisted by a WE with specifically developed balance controller. The WE has actuated...
Chapter
The main goal of the Symbitron project was to develop a safe, bio-inspired, personalized wearable exoskeleton that enables SCI patients to walk without additional assistance, by complementing their remaining motor function. Here we give an overview of major achievements of the projects.
Chapter
The ankle joint muscles can contribute to balance during walking by modulating the center of pressure and ground reaction forces through an ankle moment. This is especially effective in the sagittal plane through ankle plantar- or dorsiflexion. If the ankle joints would be physically blocked to make an ankle strategy ineffective, there would be no...
Chapter
Robotic gait training is a promising tool to improve walking ability after neurological disorders. Despite its benefits, its therapeutic effects might depend on the customization of the robotic training to the patient’s capabilities. In the last years, various approaches focused on the assist-as-needed (AAN) paradigm, have been proposed to improve...
Chapter
Effectiveness of robotic gait training in rehabilitation of stroke patients remains inconclusive. A reason could be that the current robotic gait trainers do not initiate motor learning principles enough. To encourage active participation of the patient and therefore motor learning, assist-as-needed (AAN) support strategies have been implemented in...
Article
Full-text available
Background: Wearable exoskeletons can be a powerful tool for the facilitation of ambulation of complete Spinal Cord Injury (SCI) subjects, which has several psychological and physical advantages. However, exoskeleton control is difficult for this group of users and requires a long period of training. People with SCI not only lack the motor control...
Conference Paper
The main purpose of this study was to identify outcome measures that developers working in the area of wearable robots utilize during different phases of product development. Experts in the field were invited to complete a short, anonymous, online survey. The results presented in this study focus on answers that engineers working on exoskeletons fo...
Article
Full-text available
The human leg joints play a major role in balance control during walking. They facilitate leg swing, and modulate the ground (re)action forces to prevent a fall. The aim of this study is to provide and explore data on perturbed human walking to gain a better understanding of balance recovery during walking through joint-level control. Healthy walki...
Conference Paper
Robotic gait training is a promising tool for gait rehabilitation in people with neurological disorders. Including intuitive assessment and automatic adaptation of robotic assistance into robotic training is expected to further improve therapy outcomes. This contribution presents a novel performance-based adaptive controller, which adjusts robotic...
Article
Full-text available
Background: Lower extremity exoskeletons are mainly used to provide stepping support, while balancing is left to the user. Designing balance controllers is one of the biggest challenges in the development of exoskeletons. The goal of this study was to design and evaluate a balance controller for a powered ankle-foot orthosis and assess its effect...
Chapter
Full-text available
Humans have a natural ability to haptically interact with other humans, for instance while physically assisting a child to learn how to ride a bicycle. A recent study has shown that haptic human-human interaction can improve individual motor performance and motor learning rate while learning to track a continuously moving target with a visuomotor r...
Article
Full-text available
Whenever a perturbation occurs during walking we have to maintain our balance using the recovery strategies that are available to us. Foot placement adjustment is often considered an important recovery strategy. However, because this strategy takes time it is likely a poor option if the foot is close to contact at the instant a perturbation occurs....