Harnessing Energy of a Treadmill for Push-Off Assistance During Walking: a Proof of Concept study.

Various approaches in ankle exoskeleton design and control have recently been proposed and implemented, but few have been able to produce devices suitable for rehabilitation in clinical environment. In a recent in-silico study, we proposed a novel device: Ankle Exoskeleton using Treadmill Actuation for Push-off assistance (AN-EXTRA-Push). Using a brake and an elastic tendon, it harnesses energy of a moving treadmill during stance phase, then releases it during push-off to aid with plantarflexion torque generation.

Toward improving the specificity of perturbation-based training through assessment of dynamic balancing responses: a series of N-of-1 studies in subacute stroke.

Perturbation-based balance training (PBT) has been shown to improve reactive balancing abilities in chronic stroke. To inform future investigations in the subacute phase of stroke, the objective of this series of N-of-1 studies was to investigate the range of balancing responses to unexpected mechanical perturbations applied to the pelvis during walking on an instrumented treadmill before and after PBT training. Three subacute stroke subjects were assessed on each occasion with clinical tests and biomechanical measurements following perturbations applied in forward, backward, inward and outward directions.

Wide Skis As a Potential Knee Injury Risk Factor in Alpine Skiing.

Alpine skis with wider waist widths have recently become more popular. With such skis, the contact point of the ground reaction force during ski turns is displaced more medially from beneath the sole of the outer ski, which may present an increased risk of injury. The aim of this study was to investigate knee joint kinetics, kinematics, and lower limb muscle activation as a function of changes of the ski waist width in a laboratory setting.

Movement strategy and EMG activities of the upper extremity at assisted reaching exercise with a 7 DOF collaborative robot.

Recovering of upper extremity functions is important for stroke patients to perform various tasks in daily life. For better rehabilitation outcomes and accurate measurement, robot assisted exercises have been developed. However, there are limited number of studies related to arm muscles activities corresponding to task complexity.

Biomechanics of In-Stance Balancing Responses Following Outward-Directed Perturbation to the Pelvis During Very Slow Treadmill Walking Show Complex and Well-Orchestrated Reaction of Central Nervous System.

Multiple strategies may be used when counteracting loss of balance during walking. Placing the foot onto a new location is not efficient when walking speed is very low. Instead medio-lateral displacement of center-of-pressure, rotation of body segments to produce a lateral ground-reaction-force, and pronounced braking of movement in the plane of progression is used.

Assessment of dynamic balancing responses following perturbations during slow walking in relation to clinical outcome measures for high-functioning post-stroke subjects.

Background: Generating appropriate balancing reactions in response to unexpected loss of balance during walking is important to prevent falls. The purpose of this study was to assess dynamic balancing responses following pushes to the pelvis in groups of post-stroke and healthy subjects.

Methods: Forty-one post-stroke subjects and forty-three healthy subjects participated in the study.

Emulation of hill walking and turning on Balance Assessment Robot: A preliminary study.

Gait training after stroke is often associated with rehabilitation robotics and virtual environment in order to simulate practice of different functional gait tasks. Changing direction, walking up and down the slope are important skills that need to be practiced. The aim of this preliminary study was to compare inclined treadmill walking and turning conditions with its emulations on a recently developed Balance Assessment Robot for Treadmill walking (BART) on a basis of ground reaction forces (GRF) and lower extremity electromyography (EMG).

Influence of Treadmill Speed and Perturbation Intensity on Selection of Balancing Strategies during Slow Walking Perturbed in the Frontal Plane.

Background: Common understanding is that adequate foot placement (stepping strategy) is crucial in maintaining stability during walking at normal speed. The aim of this study was to investigate strategies that humans use to cope with lateral perturbations during very slow walking.

Methods: Ten healthy individuals underwent an experimental protocol whereby a set of perturbations directed inward (medially to a stance leg) and outward (laterally to a stance leg) of three intensities ( = 5%, = 10%, and = 15% of body weight), applied at three instances of a stance phase, were delivered in random order to the pelvis using a balance assessment robot while walking on a treadmill at three walking speeds ( = 0.

Feasibility of robot-based perturbed-balance training during treadmill walking in a high-functioning chronic stroke subject: a case-control study.

Background: For stroke survivors, balance deficits that persist after the completion of the rehabilitation process lead to a significant risk of falls. We have recently developed a balance-assessment robot (BAR-TM) that enables assessment of balancing abilities during walking. The purpose of this study was to test feasibility of using the BAR-TM in an experimental perturbed-balance training program with a selected high-functioning stroke survivor.

The effect of haptic interaction between balance assessment robot and pelvis on muscle activation of leg muscles.

Admittance control is considered as a promising paradigm in rehabilitation that provides us with means to establish well controlled and adjustable interaction and cooperation between rehabilitation devices and patients. Recently we developed balance assessment robot (BAR) for studying postural responses during walking as well as for pelvis manipulation during walking that implements admittance control as a mean of interaction with user. In this study we evaluated the characteristics of transparent haptic interaction and investigated whether transparent haptic interaction induces adaptations in muscle activation patterns with respect to free walking.

A novel robot-assisted training approach for improving gait symmetry after stroke.

Gait asymmetry as a consequence of hemiparesis is known as a serious long-term disability, where typical compensatory gait movements are used by stroke subjects in order to cope with their daily activities. This study presents a gait symmetry training approach consisting of the adaptive robot assistance with the combination of the visual feedback integrated in Balance Assessment Robot for treadmill walking (BAR-TM). The support algorithm is based on gait temporal parameters that change the level of assistive support, which was triggered at different gait subphase events.

An effective balancing response to lateral perturbations at pelvis level during slow walking requires control in all three planes of motion.

In this study we investigated balancing responses to lateral perturbations during slow walking (0.85m/s). A group of seven healthy individuals walked on an instrumented treadmill while being perturbed at the level of waist at left heel strike in outward and inward lateral directions.

The comparison of stepping responses following perturbations applied to pelvis during overground and treadmill walking.

Background: Treadmills are used frequently in rehabilitation enabling neurologically impaired subjects to train walking while being assisted by therapists. Numerous studies compared walking on treadmill and overground for unperturbed but not also perturbed conditions.

Objective: The objective of this study was to compare stepping responses (step length, step width and step time) during overground and treadmill walking in a group of healthy subjects where balance assessment robots applied perturbing pushes to the subject's pelvis in sagittal and frontal planes.

A novel robot for imposing perturbations during overground walking: mechanism, control and normative stepping responses.

Background: The most common approach to studying dynamic balance during walking is by applying perturbations. Previous studies that investigated dynamic balance responses predominantly focused on applying perturbations in frontal plane while walking on treadmill. The goal of our work was to develop balance assessment robot (BAR) that can be used during overground walking and to assess normative balance responses to perturbations in transversal plane in a group of neurologically healthy individuals.

Kinematics of turning during walking over ground and on a rotating treadmill.

Background: After neurological injury, gait rehabilitation typically focuses on task oriented training with many repetitions of a particular movement. Modern rehabilitation devices, including treadmills, augment gait rehabilitation. However, they typically provide gait training only in the forward direction of walking, hence the mechanisms associated with changing direction during turning are not practiced.

Adjusting kinematics and kinetics in a feedback-controlled toe walking model.

Background: In clinical gait assessment, the correct interpretation of gait kinematics and kinetics has a decisive impact on the success of the therapeutic programme. Due to the vast amount of information from which primary anomalies should be identified and separated from secondary compensatory changes, as well as the biomechanical complexity and redundancy of the human locomotion system, this task is considerably challenging and requires the attention of an experienced interdisciplinary team of experts. The ongoing research in the field of biomechanics suggests that mathematical modeling may facilitate this task.

Psychophysiological responses to robot training in different recovery phases after stroke.

Psychophysiological responses have become a valuable tool in human-robot interaction since they provide an objective estimate of the user's psychological state. Unfortunately, their usefulness in rehabilitation robotics is uncertain since they are influenced by both physical activity and pathological conditions such as stroke. We performed psychophysiological measurements in subacute and chronic stroke patients as well as healthy controls during a reaching and grasping exercise task performed in a multimodal virtual environment.

Challenges in biocooperative rehabilitation robotics.

Psychological states such as mood, motivation and engagement are known to be critical for the success of rehabilitation, and encouraging unmotivated stroke patients improves the likelihood of their eventual recovery. Psychological factors can be incorporated into the closed-loop control of biocooperative rehabilitation systems, augmenting the device with critical information about the patient state. However, in rehabilitation robotics, interpretation of psychophysiological measurements is made complex by the multi-task environment, the presence of strenuous physical activity and patient's damage to the central and autonomic nervous systems.

River multimodal scenario for rehabilitation robotics.

This paper presents the novel "River" multimodal rehabilitation robotics scenario that includes video, audio and haptic modalities. Elements contributing to intrinsic motivation are carefully joined in the three modalities to increase motivation of the user. The user first needs to perform a motor action, then receives a cognitive challenge that is solved with adequate motor activity.

Task difficulty adjustment in biocooperative rehabilitation using psychophysiological responses.

This study presents a biocooperative feedback loop where the difficulty of an upper extremity rehabilitation task is adjusted based on four psychophysiological measurements: heart rate, skin conductance, respiration and skin temperature. They are used both by themselves and in combination with task performance and biomechanics. Different variants of linear discriminant analysis are used for data fusion, including a variant that can adjust the fusion rules online and thus gradually adapt to the subject.

Psychophysiological measurements in a biocooperative feedback loop for upper extremity rehabilitation.

This paper examines the usefulness of psychophysiological measurements in a biocooperative feedback loop that adjusts the difficulty of an upper extremity rehabilitation task. Psychophysiological measurements (heart rate, skin conductance, respiration, and skin temperature) were used both by themselves and in combination with task performance and biomechanics. Data fusion was performed with discriminant analysis, and a special adaptive version was implemented that can gradually adapt to a subject.

Evaluation of upper extremity robot-assistances in subacute and chronic stroke subjects.

Background: Robotic systems are becoming increasingly common in upper extremity stroke rehabilitation. Recent studies have already shown that the use of rehabilitation robots can improve recovery. This paper evaluates the effect of different modes of robot-assistances in a complex virtual environment on the subjects' ability to complete the task as well as on various haptic parameters arising from the human-robot interaction.

Psychophysiological responses to robotic rehabilitation tasks in stroke.

This paper presents the analysis of four psychophysiological responses in post-stroke upper extremity rehabilitation. The goal was to determine which psychophysiological responses would provide the most reliable information about subjects' psychological states during rehabilitation. Heart rate, skin conductance, respiration, and skin temperature were recorded in a stroke group and a control group during two difficulty levels of a pick-and-place task performed in a virtual environment using a haptic robot and during a cognitive task.

Compensatory mechanisms during walking in response to muscle weakness in spinal muscular atrophy, type III.

Our knowledge on altered neurological control of walking due to weakness of various muscle groups of the lower extremities is limited. The aim of this study was to assess kinematic, kinetic and electromyographic (EMG) walking patterns in a functionally homogeneous group of seven subjects with spinal muscular atrophy, type III (SMA group) and compare them with normal data obtained from nine healthy subjects (CONTROL group) in order to identify characteristic compensatory changes. Muscle strength at the ankle and knee joints was assessed using isokinetic dynamometry to determine variability in muscle strength: this was found to be similar in the two groups.