Keywords: Orthotics - modeling and simulation, Robotic orthoses - design and development, Human-machine interfaces and robotic applications
Abstract: Knee osteoarthritis (Knee-OA) is a disease caused by age-related muscle weakness, obesity, or sports injury, and it has been estimated to occur in approximately half of all people by the age of 85. One of the characteristics of knee-OA is rotation dyskinesia of the knee joint due to the degeneration of the system around the knee. This rotation movement, a key element of walking, is crucial for impact absorption, balanced walking, and stabilization of the knee joint. In the present study, we focused on the rotation of the lower leg relative to the movement of the ankle joint during the walking stance phase, and we developed a mechanical orthosis that induces rotation of the lower leg in conjunction with the movement of the ankle joint mechanically. The mechanical induction of rotation movement uses the movement difference due to the angle change of the inside and outside bars in conjunction with the ankle angle. We verified the effectiveness of the developed orthosis by measuring the amount of rotation and by administering the Womac test in 5 subjects with knee osteoarthritis. The results confirmed the effectiveness of our orthosis.

Keywords: Biomechanics and robotics in physical rehabilitation, Human-machine interfaces and robotic applications, Design and development in rehabilitation robotics
Abstract: 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). First, a healthy participant walked overground straight, turning to left and right direction at a predefined walking speed and radius, and walking uphill and downhill on a sloped BART. After that, the participant walked with the proposed and integrated emulation strategies on BART, designed to induce hill walking and turning in human locomotion behaviour. The results of hill walking emulation show high similarities with the inclined treadmill walking, while turning emulation show high similarities when comparing GRF data and some similarities to the overground turning behaviour when comparing EMG data. Further studies on a group of subjects should compare inclined treadmill walking and turning with proposed emulation in order to investigate feasibility of the proposed approach in rehabilitation.

Keywords: Assistive robotics - home robots, Clinical evaluation in robot-aided rehabilitation
Abstract: Our research team has developed two versions of an ankle robot for children with cerebral palsy. Both devices provide three degrees of freedom and are connected to an airplane video game. The child uses his/her foot as the controller for the plane and attempts to fly through a series of hoops arranged to manipulate the foot across the ankle joint. The first device is for lab-based therapy and four children have completed 20 sessions each with the device. The second device is for home-based therapy and two children have completed a 28-day trial using the device at home. Both studies were done under Institutional Review Board approval and all participants improved ankle range of motion. Further studies are ongoing to gather more data and validate the results

Keywords: Assistive robotics - home robots, Wearable robotic systems, Robot-aided mobility
Abstract: Wearable exoskeletons show promise as a means for compensating lost function as well as for providing optimal assistance for maximal therapeutic benefit during everyday tasks. Development of lightweight spring systems for efficient storage and return are proposed as a key component in the successful deployment of wearable exoskeletons for individuals with neurological deficits. Both spring steel and natural rubber are common materials used in energy storage, but have not been directly compared by metrics such as energy storage density, energy storage efficiency, and hysteresis. In this work, we perform cyclic loading tests on spring steel extension springs of varying wire diameter and natural rubber tubing of varying wall thicknesses. We then use measured load-extension profiles to illustrate and compute metrics to better quantify the energy storing capabilities of each material and their appropriateness for use as energy storing and returning components in wearable robotic applications. Results show that natural rubber has a higher capacity for energy storage per unit weight in comparison to steel springs. Hysteresis is also higher in natural rubber and can be dramatically reduced by applying adequate pre-strain at levels greater than the anticipated strain during use.

Keywords: Biomechanics and robotics in physical rehabilitation, Design and development in rehabilitation robotics
Abstract: Rehabilitation robotics is an emerging field in which gait training has been largely automated allowing more intensive, repetitive motions which are important for facilitating recovery. However, there is no clear evidence that robot-assisted gait training is superior to conventional therapy which does not restore normal gait patterns in the majority of patients. A limitation of current approaches to gait therapy is that they do not consider mechanisms of inter-leg coordination and how the sensory feedback from one leg affects the motion of the other leg, but instead impose motion on the impaired limb. Recent research suggests that utilizing the coupling between limbs in stroke rehabilitation therapies could lead to improved functional outcome. This paper systematically explores and analyzes a sensorimotor mechanism of inter-leg coordination that is stimulated through sudden unilateral low-stiffness perturbations to the walking surface. The potential contribution of each sensory modality to the perception and response of the perturbation will be investigated. Additionally, the neural pathway that relays the sensory signal into the motor output will be described in order to fully characterize this sensorimotor mechanism of inter-leg coordination. This work provides physiological understanding of inter-leg coordination that will benefit robot-assisted gait therapies.

Keywords: Assistive robotics, Human-machine interfaces and robotic applications, Control strategies in rehabilitation robotics
Abstract: Task-oriented therapy consists of three stages: demonstration, observation and assistance. While demonstration using robots has been extensively studied, the other two stages rarely involve robots. This paper focuses on the transition between observation and assistance. More specifically, we tackle the robot's decision making problem of whether to assist a patient or not based on the observation. The proposed method is to train a discrete tunnel shape 3-D decision boundary through correct demonstration to classify motions. Additional conditions such as slow progress, self correction and overshot motions are taken into account of the decision making. Preliminary experiments have been performed on BAXTER robot for a cup reaching task. The BAXTER robot is programmed to react according to the decision boundary. It assists the patient when the patient's hand position is determined by the proposed algorithm to be unacceptable. Multiple cases including correct motion, continuous assistance, overshot, misaim and slow progress are tested. Results have confirmed the feasibility of the proposed method, which can reduce the current shortage of physical rehabilitation therapists.

Keywords: New technologies and methodologies in human movement analysis, Human-machine interfaces and robotic applications, Integrated diagnostic and therapeutic systems
Abstract: We propose a methodology to classify motion of subjects with cerebral palsy based on RGB image sequences. A new dataset with 2D facial landmark trajectories was acquired from RGB images of people with and without disabilities while performing specific types of movements. Depending on these movements, some parts of the face can be occluded during the sequence and we are able to recover the 3D face's shape and its motion based on the Structure from Motion framework. Using the 3D structure and the motion, we propose two different motion descriptors, one is focused on describing the spatial distribution of the motion and the other on the temporal distribution. Finally, we discuss the physical meaning of these descriptors and show that they are very informative about the degree of the subjects disabilities. Our descriptor can classify people with and without cerebral palsy from 2D image sequences.

Keywords: Assistive robotics, Human-machine interfaces and robotic applications, Design and development in rehabilitation robotics
Abstract: This paper presents a voice control interface prototype for assistive robots aiming to help people living with upper limb disabilities to perform daily activities autonomously. Assistive robotic devices can be used to help people with upper-body disabilities gain more autonomy in their daily life. However, it is very difficult or even impossible for certain users to control the robot with conventional control systems (e.g. joystick, sip-and-puff). This paper presents the design and preliminary evaluation of a voice command system prototype for the control of assistive robotic arms’ movements. This work aims at making the control of assistive robots more intuitive and fluid, and to perform various tasks in less time and with a lesser effort. The prototype of the voice command interface developed is first presented, followed by two experiments with five able-bodied subjects in order to assess the system’s performance and guide future development.

Keywords: Orthotics - modeling and simulation, Exoskeletons, Human-machine interfaces and robotic applications
Abstract: The human ankle provides significant positive power during the stance phase of walking, which has resulted in studies focusing on methods to reduce the energetic walking cost by augmenting the ankle with exoskeletons. Recently, a few devices have successfully reduced the metabolic cost of walking by replacing part of the biological ankle plantar flexor torque. Despite these achievements, development of assistive ankle devices remains challenging, partly because the current practice of design and control of powered exoskeletons is highly time and effort consuming, which prevents quickly exploring different design and control parameters. Predictive simulations using musculoskeletal models coupled with robotic devices may facilitate the process of design and control of assistive devices. In this study, we simulate human walking augmented by a powered ankle exoskeleton. The walking problem was formulated as a predictive dynamic optimization in which both the optimal assistive device torque and the gait were solved simultaneously. Cases with exoskeletons assisting one ankle and both ankles were considered. The results showed that the energetic cost of walking could be reduced by 45% with one ankle augmented, and by 52% with both ankles augmented. This study contributes towards the goal of providing optimal assistive torque through external devices and theoretical peak reductions that could be expected from such devices.

Keywords: New technologies and methodologies in biomechanics, Neural processes in rehabilitation, Technologies for neurodegenerative disorders
Abstract: Many stroke survivors suffer from hemiparesis, a condition that results in impaired walking ability. Walking ability is commonly assessed by walking speed, which is dependent on propulsive force generation both in healthy and stroke populations. Propulsive force generation is determined by two factors: ankle moment and the posture of the trailing limb during push-off. Recent work has used robotic assistance strategies to modulate propulsive force with some success. However, robotic strategies are limited by their high cost and the technical difficulty of fitting and operating robotic devices in a clinical setting.

Here we present a new paradigm for goal-oriented gait training that utilizes a split belt treadmill to train both components of propulsive force generation, achieved by accelerating the treadmill belt of the trailing limb during push off. Belt accelerations require subjects to produce greater propulsive force to maintain their position on the treadmill and increase trailing limb angle through increased velocity of the accelerated limb.

We hypothesized that locomotor adaptation to belt accelerations would result in measurable after effects in the form of increased propulsive force generation. We tested our protocol on healthy subjects at two acceleration magnitudes. Our results show that 79% of subjects significantly increased propulsive force generation following training, and that larger accelerations translated to larger, more persistent behavioral gains.

Keywords: Assistive robotics, Wearable robotic systems, Clinical evaluation in robot-aided rehabilitation
Abstract: In this paper, we present the new personalized 3D printed soft robotic hand for providing rehabilitation training and daily activities assistance to stroke survivors. The Soft-Elastic Composite Actuator (SECA) on the robotic hand is direct 3D printed to accommodate with different finger sizes. Flexion and extension can be actively facilitated on the SECA using the same pressurizing source. Iterative learning model predictive control (ILMPC) method is used to be the control algorithm of SECA. At 160 kPa of maximum input pressure, results show that the actuator bending angles can reach to 137°, and tip output force can also reach to 2.45 N. Multiple 3D printed SECAs are integrated to a 3D printed hand base and then to be worn on stroke survivors. Two stroke survivors are recruited to evaluate the intention-based rehabilitation training with the 3D printed soft robotic hand, which improvement of their hand function can be observed on performing some daily tasks such as grasping a coin.

Keywords: Assistive robotics, Body-machine interfaces, Robotic prostheses - neural interfaces
Abstract: Control of lower-limb assistive devices may benefit from predicting the intent of individuals in advance of upcoming motion, rather than estimating the current states of their motion. Human lower-limb motion estimation using ultrasound (US) image-derived features of skeletal muscle has been demonstrated. However, predictability of motion in time remains an open question. The objective of this study was to assess the predictability of distal lower-limb motion using US image features of RF muscle during non-weight-bearing knee flexion/extension. A series of time shifts was introduced between the US features and the joint position in 67 ms steps from 0 ms (i.e., estimation) up to predicting 467 ms in advance. A US-based algorithm to estimate lower-limb motion was then used to predict the knee joint position in time using the US features after introducing the time shifts. The accuracy of joint motion prediction after each time shift was compared to the accuracy of joint motion estimation. The reliability of the prediction was then assessed using an ANOVA test. The motion prediction accuracy was found to be reliable up to 200 ms, where the average root mean square error (RMSE) of prediction across 9 healthy subjects was 0.89 degrees greater than the average RMSE (7.39 degrees) of motion estimation for the same group of subjects. These findings suggest a reliable prediction of upcoming lower-limb motion is feasible using the US features of skeletal muscle up to a certain point.

Keywords: Assistive robotics, Design and development in rehabilitation robotics, Human-machine interfaces and robotic applications
Abstract: Autonomy and social inclusion can reveal themselves everyday challenges for people experiencing mobility impairments. These people can benefit from technical aids such as power wheelchairs to access mobility and overcome social exclusion. However, power wheelchair driving is a challenging task which requires good visual, cognitive and visuo-spatial abilities. Besides, a power wheelchair can cause material damage or represent a danger of injury for others or oneself if not operated safely. Therefore, training and repeated practice are mandatory to acquire safe driving skills to obtain power wheelchair prescription from therapists. However,conventional training programs may reveal themselves insufficient for some people with severe impairments. In this context, Virtual Reality offers the opportunity to design innovative learning and training programs while providing realistic wheelchair driving experience within a virtual environment. In line with this, we propose a user-centered design of a multisensory power wheelchair simulator. This simulator addresses classical virtual experience drawbacks such as cybersickness and sense of presence by combining 3D visual rendering, haptic feedback and motion cues. It relies on a modular and versatile workflow enabling not only easy interfacing with any virtual display, but also with any user interface. This paper presents the design of the first implementation as well as its first commissioning through pre-tests.

Keywords: Assistive robotics, Wearable robotic systems, Exoskeletons
Abstract: Wool harvesting remains an important industry in Australia, but its workers suffer from extreme rates of injury, in particular, the lower back injuries. Reducing injuries in sheep shearing could be as simple as extending shearer rest periods between sheep, but the effect of this has not previously been studied. The lumbar flexion-relaxation phenomenon is present in sheep shearing and the onset angle of this phenomenon can provide insight into lower back injury risk. The increase in the onset angle of lumbar flexion-relaxation over several work-rest periods for a simulated sheep shearing task is studied. The rate of increase in the onset angle of lumbar flexion-relaxation was higher when shorter breaks were taken for all participants at least unilaterally, indicating that longer rest breaks could reduce back injury risk. Due to the constraints of the sheep shearing occupation, this type of intervention is better suited to learner and novice shearers. Assistive robotic devices would be more suited to reduce injuries in expert shearers, and some insight is provided for the application of these within sheep shearing. Further study of this phenomenon in sheep shearing could provide additional insight to developing an assistive device that could reduce injury.

Keywords: New technologies and methodologies in biomechanics, Clinical evaluation in robot-aided rehabilitation, New technologies and methodologies in human movement analysis
Abstract: The aim of this work is to present a novel robot-based method to assess the sources of a lack of functionality in patients with recent traumatic wrist injuries. Post-traumatic patients experience limited range of motion as well as strength and proprioceptive deficits. These dysfunctions are related to different complications that usually follow the injuries: pain, increased rigidity, lack of movement fluency and loss of stability could arise differently, according to the severity, site and kind of lesion. Their quantitative evaluation could be essential to target rehabilitation treatments to the specific problem and to optimize and speed up the functional recovery. The use of robotic devices for assessment not only ensures objectivity and repeatability, but could also help to estimate the goodness of the evaluation itself, in terms of reliability and patient’s engagement. Ten subjects with different types of wrist injuries were enrolled in this study and required to perform passive robot-guided reaching movements. Forces and angular positions were used to evaluate subject’s range of motion, rigidity and pain that, considered together, allowed a comprehensive characterization of the level of healing and functionality achieved by each subject.

Keywords: Robot-aided mobility, Control strategies in rehabilitation robotics, Human-machine interfaces and robotic applications
Abstract: There has been a growth in the design and use of power assist devices for manual wheelchairs (MWCs) to alleviate the physical load of MWC use. A pushrim-activated power-assisted wheel (PAPAW) is an example of a power assist device that replaces the conventional wheel of a MWC. Although the use of PAPAWs provides some benefits to MWC users, it can also cause difficulties in maneuvering the wheelchair. In this research, we examined the characteristics of wheelchair propulsion when using manual and powered wheels. We used the left and right wheels’ angular velocity to calculate the linear and angular velocity of the wheelchair. Results of this analysis revealed that the powered wheel’s controller is not optimally designed to reflect the intentions of a wheelchair user. To address some of the challenges with coordinating the pushes on PAPAWs, we proposed the design of a user-intention detection framework. We used the kinematic data of MWC experiments and tested six supervised learning algorithms to classify one of four movements: “not moving”, “moving straight forward”, “turning left”, and “turning right”. We found that all the classification algorithms determined the type of movement with high accuracy and low computation time. The proposed intention detection framework can be used in the design of learning-based controllers for PAPAWs that take into account the individualized characteristics of wheelchair users. Such a system may improve the experience of PAPAW users.

Keywords: Biomechanics and robotics in physical rehabilitation, Design and development in rehabilitation robotics
Abstract: Assessing proprioception is important for understanding and treating sensorimotor impairments. Many daily tasks require bimanual manipulation of objects, but state of the art methods for the assessment of proprioception are far away from bimanual activities, and instead evaluate sensorimotor integrity in oversimplified and often unimanual goal-directed tasks. Here, we developed a new device and method to assess proprioception and force production by simulating a realistic bimanual behavior. Twelve healthy participants held a physically coupled object – a sensorized box – and matched target orientations about the three principal axes without and with added weights. Our preliminary findings indicate that bimanual proprioception during orientation matching depends on the axis of rotation. For example, in rotations about the lateral axis of the body, underestimation and overestimation of the target angle depends on its orientation in a body-centered reference frame: participants tended to underestimate targets that required rotation far away from the body and overestimated angles that required rotation towards the body. We also found that for the same rotation axis, the larger were the rotations, the higher was the force applied. Moreover, we also found that fatigue causes undershoot in orientation matching. In the future, this tool could be adopted for assessment and treatment of sensorimotor deficits in bimanual functional tasks.

Keywords: Assistive robotics, Technologies for neurodevelopmental disorders, Exoskeletons
Abstract: Children with hand motor impairment due to cerebral palsy, traumatic brain injury, or pediatric stroke are considerably affected in their independence, development, and quality of life. Treatment conventionally includes task-oriented training in occupational therapy. While dose and intensity of hand therapy can be promoted through technology, these approaches are mostly limited to large stationary robotic devices for non-task-oriented training, or passive wearable devices for children with mild impairments. Here we present PEXO, a fully wearable actuated pediatric hand exoskeleton to cover the special needs of children (6 to 12 years of age) with strong impairments in hand function. Through three degrees of freedom, PEXO provides assistance in various grasp types needed for the execution of functional tasks. It is lightweight, water proof, and inherently interacts safely with the user. It meets mechanical requirements such as force, fast closing movement, and battery lifetime derived from literature and discussions with clinicians. Appealing appearance, user-friendly design, and intuitive control with visual feedback of forearm muscle activity should keep the user motivated during training in the clinic or at home. A pilot test with a 6-years old child with stroke showed that PEXO can provide assistance in grasping various objects weighing up to 0.5~kg. These are promising first results on the way to make hand exoskeletons accessible for children with neuromotor disorders.

Keywords: Assistive robotics, Biomechanics and robotics in physical rehabilitation, Robot-aided living
Abstract: Rehabilitative exercise for people suffering from upper limb impairments has the potential to improve their neuro-plasticity due to repetitive training. Our study investigates the usefulness of Electroencephalogram and Electromyogram (EMG) signals for incorporation in human-robot interaction loop. Twenty healthy participants recruited who performed a series of physical and cognitive tasks, with an inherent fatiguing component in those tasks. Here we report observed effects on EMG signals. Participants performed a Biceps curl repetitions using a suitable dumbbell in three phases. In phase 1, the initial weight was set to achieve maximum voluntary contraction (MVC). Phase 2 followed with 80% MVC and phase 3 had 60% MVC. After each phase, they had a break around 3 minutes. EMG data were acquired from Biceps, Triceps, and Brachioradialis muscles. Different EMG features were explored to inform on muscle fatigue during this interaction. Comparing EMG during the first and last dumbbell of each phase demonstrated that the muscle fatigue had caused an increase in the average power (94% of cases) and amplitude (91%) and a decrease in the mean (80%) and the median frequency (57%) of EMG, which was more noticeable in Biceps. The results from integrated EMG showed a continuous rise in all three muscles which was more pronounced in Biceps muscle. Given these results, we identify EMG average power as the most reliable feature for informing on muscle fatigue.

Keywords: Biomechanics and robotics in physical rehabilitation, Robotic platforms in neuroscience, New technologies and methodologies in human movement analysis
Abstract: Proprioception, the ability to sense body position and limb movements in space without visual feedback, is one of the key factors in controlling body movements and performing activities of daily living. However, this capability might be affected after neural injuries such as stroke. The objective of this paper is to investigate if a robotic training protocol improves the end-position reaching proprioceptive sense in three-dimensional (3D) space. As an initial step towards clinical application, a robotic platform was employed to train the end-position proprioceptive sense in six healthy participants. At the end of each training trial, participants were provided with visual feedback to help them move their hands to the exact locations confirmed through haptic feedback. Their performance was evaluated before and after the training in an assessment phase during which participants were asked to move from the start position to the same two targets as well as an additional third one without any visual or haptic feedback. The results from this study show significant improvements in overall reaching accuracy and trajectory smoothness demonstrated by 41% decrease in the average end-position error and 13% reduction in the average index of curvature after the training. This research suggests the potential of designing robotic rehabilitation protocols for improving 3D proprioception.

Keywords: Biomechanics and robotics in physical rehabilitation, Robotic platforms in neuroscience, Exoskeletons
Abstract: Exoskeleton design is based on achieving representative torques for both active and passive joint mechanics for a given task. The latter has been typically estimated for static postures during relaxed muscle activity. However, some studies have shown that differences in the estimates during voluntary motion versus isometric postures have resulted in lower impedance estimates during active muscle activity. The objective of this study was to determine if the estimates for the passive joint impedance of the human ankle exhibited the same reduction during relaxed muscle states with an externally imposed movement over static posture estimates. System identification techniques were used to analyze the passive joint impedance as a second-order model with inertia, damping, and stiffness. The experimental results showed little differences for the inertia and damping coefficients; however, a 10 to 34% reduction in the passive stiffness estimate was observed during movement when compared to static posture estimates. It is postulated that the 22% increase in angular velocity of the perturbations due to the superimposed externally imposed motion may be a contributing factor to these statistically different estimates. This reduced passive stiffness yields possibly new insights into muscle mechanics and applications to exoskeleton design. With lower torque and power estimates for passive resistance, reductions in motor sizing and inertial effects could lead to improved overall performance.

Keywords: Assistive robotics, Human-machine interfaces and robotic applications, Wearable robotic systems
Abstract: Active assistive devices have been designed to augment the hand grasping capabilities of individuals with spinal cord injuries (SCI). An intuitive bio-signal of wrist extension has been utilized in the device control, which imitates the passive grasping effect of tenodesis. However, controlling these devices in this manner limits the wrist joint motion while grasping. This paper presents a novel hybrid control interface and corresponding algorithms (i.e., a hybrid control method) of the Semi-soft Assistive Glove (SAG) developed for individuals with C6/C7-SCI. The secondary control interface is implemented to enable/disable the grasp trigger signal generated by the primary interface detecting the wrist extension. A simulation study reveals that the hybrid control method can facilitate grasping situations faced in daily activities. Empirical results with three healthy subjects suggest that the proposed method can assist the user to reach and grasp objects with the SAG naturally.

Keywords: Biomechanics and robotics in physical rehabilitation, Integrated diagnostic and therapeutic systems, Wearable robotic systems
Abstract: Wearable sensors provide a foundation for development of wearable robotic technology to be used in clinical applications. Inertial motion capture (IMC) has emerged as a viable alternative to more cumbersome, non-portable optical methods. However, it is unclear how well IMC can measure the small changes in gait function needed to gauge recovery. In this study, we evaluate the sensitivity of IMC compared to OMC to small changes in gait on a cohort of unimpaired individuals during treadmill walking. Eight individuals walked on a split-belt treadmill with five randomized conditions: right belt speed decrementing at 0.05 m/s from 1.0 m/s, all with left belt held at 1.0 m/s, simulating recovery of hemiparetic gait. We extracted the root mean square deviation (RMSD) of joint kinematics between limbs and within the limb with modulated gait speed as the main outcome measure. We used linear mixed models to identify differences in sensitivity to changes in gait asymmetry and gait speed. Based on these models, we estimated the minimal detectible interval in gait parameters. We found that IMC was capable of measuring a difference in gait speed of 0.08 m/s, roughly the equivalent of two weeks recovery progress. Statistically we could not conclude a difference of sensitivity between IMC and OMC, although there is a strong trend that IMC is more sensitive to changes in gait. We conclude that IMC is a valid tool to measure progress in gait kinematics over the course of recovery.

Keywords: New technologies and methodologies in human movement analysis, Wearable robotic systems
Abstract: The trend toward soft wearable robotic systems creates a compelling need for new and reliable sensor systems that do not require a rigid mounting frame. Despite the growing use of inertial measurement units (IMUs) in motion tracking applications, sensor drift and IMU-to-segment misalignment still represent major problems in applications requiring high accuracy. This paper proposes a novel 2-step calibration method which takes advantage of the periodic nature of human locomotion to improve the accuracy of wearable inertial sensors in measuring lower-limb joint angles. Specifically, the method was applied to the determination of the hip joint angles during walking tasks. The accuracy and precision of the calibration method were accessed in a group of N = 8 subjects who walked with a custom-designed inertial motion capture system at 85% and 115% of their comfortable pace, using an optical motion capture system as reference. In light of its low computational complexity and good accuracy, the proposed approach shows promise for embedded applications, including closed-loop control of soft wearable robotic systems.

Keywords: New technologies and methodologies in biomechanics, Biomechanics and robotics in physical rehabilitation, New technologies and methodologies in human movement analysis
Abstract: Estimating joint stiffness is of paramount importance for studying human motor control and for clinical assessment of neurological diseases. Usually stiffness estimation is performed using cumbersome instrumentations (e.g. robots), and by approximating robot joint angles and torques to the human ones. This paper proposes a methodology and an experimental setup to measure wrist joint stiffness in unstructured environments, with the twofold aim of: 1) providing a geometric framework in order to derive angular displacements and torques at the wrist Flexion/Extension (FE) and Radial/Ulnar Deviation (RUD) axes of rotation, using a subject specific kinematic model; 2) suggesting an experimental setup made of two portable sensors for motion tracking and one load cell, to allow for measurements in out-of-the-lab scenarios. We tested our method on a hardware mockup of wrist kinematics, providing a ground truth for estimated angles and torques at FE and RUD joints. The experimental validation showed average absolute errors in FE and RUD angles of 0.005 rad and 0.0167 rad respectively, and an average error of FE and RUD torques of 0.006 Nm and 0.003 Nm.

Keywords: Assistive robotics - home robots, Human-machine interfaces and robotic applications, Robot-aided living
Abstract: Individuals suffering from quadriplegia can achieve increased independence by using an assistive robotic manipulator (ARM). However, due to their disability, the interfaces that can be used to operate such devices become limited. A versatile intraoral tongue control interface (ITCI) has previously been develop for this user group, as the tongue is usually spared from disability. A previous study has shown that the ITCI can provide direct and continuous control of 6-7 degrees of freedom (DoF) of an ARM, due to a high number of provided inputs (18). In the present pilot study we investigated whether semi-automation might further improve the efficiency of the ITCI, when controlling an ARM. This was achieved by adding a camera to the end effector of the ARM and using computer vision algorithms to guide the ARM to grasp a target object. Three ITCI and one joystick control scheme were tested and compared: 1) manual Cartesian control with a base frame reference point, 2) manual Cartesian control with an end effector reference point 3) manual Cartesian control with an end effector reference point and an autonomous grasp function 4) regular JACO2 joystick control. The results indicated that end effector control was superior to the base frame control in total task time, number of commands issued and path efficiency. The addition of the automatic grasp function did not improve the performance, but resulted in fewer collisions/displacements of the target object when grasping.

Keywords: New technologies and methodologies in human movement analysis, New technologies and methodologies in biomechanics, Integrated diagnostic and therapeutic systems
Abstract: Freedom of neck range of motion has been identified for decades as an important indicator of neck health. In the past, neck motion has been measured in clinical settings using straight-plane movements that do not represent realworld ‘ecological’ performance. The tools currently used are low-fidelity analog or digital tools that rely greatly on the orientation of the person with respect to gravity, or the evaluator’s ability to accurately align protractor arms with key surface markers for angle measurement. A possible solution lies in the use of wearable sensors for tracking the motion of the neck without clinical instruction. For this purpose, the focus of this paper is on the assessment of a commercially available stretch sensitive sensor, C-Stretch® against a gold standard for motion tracking. The sensor’s accuracy and agreement for measuring neck rotations were evaluated. The results show that the stretch sensitive sensor was accurate with an average RMSE of 5.86 (SD = 4.38, n=2) and highly correlated r=0.88–0.99, (p<0.01) with Aurora, an electromagnetic tracking system. This work may lead to using wearable sensors as a costeffective, lightweight, and safe alternative to assess real-world neck range of motion for clinical application.

Keywords: Biomechanics and robotics in physical rehabilitation, New technologies and methodologies in human movement analysis, Wearable robotic systems
Abstract: Studies that investigate myoelectric prosthesis control commonly use non-disabled participants fitted with a simulated prosthetic device. This approach improves participant recruitment numbers but assumes that simulated movements represent those of actual prosthesis users. If this assumption is valid, then movement performance differences between simulated prosthesis users and normative populations should be similar to differences between actual prosthesis users and normative populations. As a first step in testing this assumption, the objective of this study was to quantify movement performance differences between simulated transradial myoelectric prosthesis hand function and normative hand function. Motion capture technology was used to obtain hand kinematics for 12 non-disabled simulated prosthesis participants who performed a functional object-manipulation task. Performance metrics, end effector movement, and grip aperture results were compared to 20 non-disabled participants who used their own hand during task execution. Simulated prosthesis users were expected to perform the functional task more slowly, with multiple peaks in end effector velocity profiles, and a plateau in grip aperture when reaching to pick up objects, when compared to non-disabled participants. This study confirmed these expectations and recommends that subsequent research be undertaken to quantify differences in actual myoelectric prosthesis hand function versus normative hand function.

Keywords: Assistive robotics, Human-machine interfaces and robotic applications, Control strategies in rehabilitation robotics
Abstract: Haptic-enabled teleoperated robots can help children with physical disabilities to reach toys by applying haptic guidance towards their toys, thus compensating for their limitations in reaching and manipulating objects. In this article we preliminarily tested a learning from demonstration (LfD) approach, where the robotic system learnt the surface that best approximated to all motion trajectories demonstrated by the participants while playing a whack-a-mole game. The end-goal of the system is for therapists or parents to demonstrate to it how to play a game, and then be used by children with physical disabilities. In this study, four adults without disabilities participated, to identify aspects that will be necessary to improve before conducting trials with children. During the demonstration phase, participants played the game in normal teleoperation, assuming the role of the therapist/parent. Then, the surface was modeled using a neural network. Participants played the game without and with the haptic guidance. The movements of the robotic system were mirrored to induce errors in movements, and thus require the guidance. Participants spent more time, moved the robot longer distances, and had jerkier movements when they played the game with the guidance than without it. Possible reasons were discussed, and several solutions were proposed to improve the system. The main contribution of this paper was the learning of a surface instead of learning a single motion trajectory.

Keywords: Biomechanics and robotics in physical rehabilitation, Human-machine interfaces and robotic applications, Design and development in rehabilitation robotics
Abstract: Occupational rehabilitation is an integral part of the recovery process for workers who have sustained injuries at the workplace. It often requires the injured worker to engage in functional tasks that simulate the workplace environment to help regain their functional capabilities and allow for a return to employment. We present a system comprised of a robotic arm for recreating the physical dynamics of functional tasks and a 3D Augmented Reality (AR) display for immersive visualization of the tasks. While this system can be used to simulate a multitude of occupational tasks, we focus on one specific functional task. Participants perform a virtual version of the task using the robot-AR system, and a physical version of the same task without the system. This study shows the results for two able-bodied users to determine if the robot-AR system produces upper-limb movements similar to the real-life equivalent task. The similarity between relative joint positions, i.e., hand-to-elbow (H2E) and elbow-to-shoulder (E2S) displacements, is evaluated within clusters based on the spatial position of the user's hand. The H2E displacements for approximately 50% of hand position clusters were consistent between the robot-AR and real-world conditions and approximately 30% for E2S displacements. The similar clusters are distributed across the entire task space however, indicating the robot-AR system has the potential to properly simulate real-world equivalent tasks.

Keywords: Design and development in rehabilitation robotics, Assistive robotics, Robot-aided mobility
Abstract: Nowadays, many people suffer from physical disabilities caused by illness or accidents. The problems in the lower limb are one of the main that interrupt the activities of daily life of these people. To assist them in the activities of daily living, many support devices for upper and lower limb movement have been developed. In this paper is proposed a new simple and low-cost pneumatic robotic mechanism for lower limb rehabilitation. We employ a pneumatic actuator so that it is possible to obtain safety for the operation and the control of the force by the appropriate regulation of the pressures in the pneumatic cylinder chambers of the robot for rehabilitation. This work deals with the development of the robot for rehabilitation from a methodology of integration of mathematical modeling with the phases of the design process. It is concluded that the results obtained are a modular design that can be improved for multiple degrees of freedom and adapted also for rehabilitation of upper limbs.

Keywords: Biomechanics and robotics in physical rehabilitation, Design and development in rehabilitation robotics, Assistive robotics
Abstract: This project aims to develop serious games for spine rehabilitation using the Kinect device and the Unity game engine. First, this paper shows a brief review about the low-cost Kinect device and the main spine movements. After, we explain the game developed and the validation of the data obtained through Kinect to spine movements. From the experimental results the game developed with the Kinect is ready to be used in patients.

Keywords: Biomechanics and robotics in physical rehabilitation, Clinical evaluation in robot-aided rehabilitation, Control strategies in rehabilitation robotics
Abstract: Progression of technology has expanded applications of smart walkers in clinical fields. However, it is essential to investigate the effects of different types of gait guidance in order to introduce smart walkers more widely throughout these fields. The purpose of this study was to identify the effects of assistive and resistive guidance on the gait of elderly people using a smart walker. Gait parameters, surface electromyography of lower limb muscles, and trunk acceleration were measured. The assistive guidance force significantly increased gait speed, step length, and cadence while increasing trunk acceleration variability. The same amount of resistive guidance force did not change gait parameters; instead, however, it restrained the speed-dependent increase of trunk acceleration variability in the mediolateral direction. An analysis of muscle activity suggested that the lower limb muscle activity could be increased by varying gait parameters including speed, step length, and cadence.

Keywords: Assistive robotics, Robot-aided mobility, Wearable robotic systems
Abstract: With the aging of the population in the United States, an increasing number of individuals suffer from mobility challenges. For such individuals, the difficulty of standing up from a seated position is a major barrier for their daily physical activities. In the paper, a novel assistive device, namely Semi-Wearable Sit-to-Stand Assist (SW-SiStA), is presented, which provides effective lower-limb assistance to overcome such difficulty for the mobility-challenged individuals. Unlike traditional exoskeletons, the SW-SiStA can be easily detached after the completion of the sit-to-stand process, and thus will not cause additional burden to the user during the subsequent ambulation. The SW-SiStA is powered with a pneumatic actuator, leverage its advantages of low cost and high power/force density. The complexity of the device is reduced by the use of a simple solenoid valve in combination with two adjustable needle valves, providing the desired individualized adjustability without the expensive proportional valves. Human testing of the device indicated that the SW-SiStA was able to provide effective sit-to-stand assistance in a natural way, and the users were able to expend significantly less muscle efforts in the process.

Keywords: Assistive robotics, Robot-aided living, Human-machine interfaces and robotic applications
Abstract: Assistive robots have the potential to support people with disabilities in their Activities of Daily Life. The drinking task has a high priority and requires constant assistance by caregivers to be executed regularly. Due to incapacitating disabilities such as tetraplegia, which is the paralysis of all limbs, affected people cannot use classic control interfaces such as joysticks. This paper presents a robotic solution to enable independent, straw-less drinking using a smart cup and no physically attached elements on the user. The system's hardware and software components are presented and the overarching control scheme described. The cup approaches the mouth utilising a user-friendly and vision-based robot control based on head pose estimation. Once contact has been established, the user can drink by tilting the cup with a force sensor-based control setup. Two experimental studies have been conducted, where the participants (mostly able-bodied and one tetraplegic), could separately experience the cup’s contactless approach and the contact-based sequence. First results show a high user acceptance rate and consistent positive feedback. The evaluation of internal data showed a high reliability of the safety-critical components with the test groups perceiving the system as intuitive and easy to use.

Keywords: Assistive robotics - home robots, Robot-aided living, Design and development in rehabilitation robotics
Abstract: This paper presents the development of a new active assistive eating device, which aims to stabilize the movements of people living with movement disorders, such as spasticity and ataxia. Many people living with upper-body incapacities are unable to eat on their own, due to movement disorders (ex. tremors, spastic motions, lack of muscular tone), resulting from various ailments like Cerebral palsy, Parkinson’s disease, Dystonia, Multiple sclerosis, strokes, and Muscular dystrophy). Our past work focused on the development of a purely mechanical device, which involved damping of the system via passive mechanical dampers. This paper extends said work by using active stabilization of user movements. The active assistance enables the design of intelligent algorithms that can assist human movements more efficiently. This active version has the benefits of being easily adjustable; the level of damping can be adjusted in real-time, depending on the user movement; different control modes are offered, and the guiding of user movements is also allowed. Firstly, the mechanical design of the device is presented, followed by the damping arrangement, the electronic design, the control algorithms and finally, the preliminary experiments are mentioned.

Keywords: Assistive robotics, Assistive robotics - home robots
Abstract: Robotic assistance presents an opportunity to benefit the lives of many people with physical disabilities, yet accurately sensing the human body and tracking human motion remain difficult for robots. We present a multidimensional capacitive sensing technique that estimates the local pose of a human limb in real time. A key benefit of this sensing method is that it can sense the limb through opaque materials, including fabrics and wet cloth. Our method uses a multielectrode capacitive sensor mounted to a robot's end effector. A neural network model estimates the position of the closest point on a person's limb and the orientation of the limb's central axis relative to the sensor's frame of reference. These pose estimates enable the robot to move its end effector with respect to the limb using feedback control. We demonstrate that a PR2 robot can use this approach with a custom six electrode capacitive sensor to assist with two activities of daily living - dressing and bathing. The robot pulled the sleeve of a hospital gown onto able-bodied participants' right arms, while tracking human motion. When assisting with bathing, the robot moved a soft wet washcloth to follow the contours of able-bodied participants' limbs, cleaning their surfaces. Overall, we found that multidimensional capacitive sensing presents a promising approach for robots to sense and track the human body during assistive tasks that require physical human-robot interaction.

Keywords: Assistive robotics, Human-machine interfaces and robotic applications, Robot-aided mobility
Abstract: Shared-control for assistive devices can increase the independence of individuals with motor impairments. However, each person is unique in their level of injury and physical constraints. Consequently, a plethora of interfaces are used to control the assistive device, depending on the individual. In order to be effective, the shared-autonomy assistance should be aware of the usage characteristics of the interface and adjust to varying performance characteristics of the person. To that end, we conduct a 23 person (9 spinal cord injured and 14 uninjured) study using three commercial interfaces used to operate powered wheelchairs, and establish performance measures to characterize interface usage. The analyses of our performance measures unveil key aspects of the interface operation that can inform features of a customizable and interface-aware control sharing framework.

Keywords: New technologies and methodologies in human movement analysis, Neural processes in rehabilitation, Biomechanics and robotics in physical rehabilitation
Abstract: Ankle dorsiflexion produced by Tibialis Anterior (TA) muscle contraction plays a significant role during human walking and standing balance. The weakened function or dysfunction of the TA muscle often impedes activities of daily living (ADL). Powered ankle exoskeleton is a prevalent technique to treat this pathology, and its intelligent and effective behaviors depend on human intention detection. A TA muscle contraction strength monitor is proposed to evaluate the weakness of the ankle dorsiflexion. The new method combines surface electromyography (sEMG) signals and sonomyography signals to estimate ankle torque during a voluntary isometric ankle dorsiflexion. Changes in the pennation angle (PA) are derived from the sonomyography signals. The results demonstrate strong correlations among the sonomyography-derived PA, the sEMG signal, and the measured TA muscle contraction force. Especially, the TA muscle strength monitor approximates the TA muscle strength measurement via a weighted summation of the sEMG signal and the PA signal. The new method shows an improved linear correlation with the muscle strength, compared to the correlations between the muscle strength and sole sEMG signal or sole PA signal, where the R-squared values are improved by 4.21 % and 1.99 %, respectively.

Keywords: Biomechanics and robotics in physical rehabilitation, Clinical evaluation in robot-aided rehabilitation
Abstract: Dynamic joint mechanics, collectively known as mechanical impedance, are often altered following upper motoneuron disease, which can hinder mobility for these individuals. Typically, assessments of altered limb mechanics are obtained while the patient is at rest, which differs from the dynamic conditions of mobility. The purpose of this study was to quantify ankle impedance during walking in individuals post-stroke, determine differences from the healthy population, and assess the relationship between impedance impairment and clinical outcome measures. Preliminary data were collected in four individuals post-stroke. Displacement perturbations were applied to the ankle during stance phase, and least-squares system identification was performed to estimate ankle impedance. In comparison to the healthy population, the paretic ankle showed reduced variation of stiffness during midstance of walking, and damping estimates during early and mid-stance were increased. Clinical measures obtained during dynamic tasks showed strong correlation with changes to the stiffness component of impedance, while clinical measures obtained passively were not correlated to stiffness. Impairment in ankle damping was not correlated with any of the measures tested. This work provides novel, preliminary insight into paretic ankle impedance during walking, differences from healthy data, and elucidates how current clinical metrics correspond to the true values of ankle stiffness and damping during gait.

Keywords: Biomechanics and robotics in physical rehabilitation, Robotic orthoses - design and development, Control strategies in rehabilitation robotics
Abstract: Single-sided motor weakness, also known as hemiparesis, is the most prevalent gait impairment among stroke survivors, which often results in gait asymmetry. Studies on robot-assisted gait training (RAGT) have shown positive effects of force feedback on spatial symmetry; somatosensory stimulation is thought to facilitate recovery of temporal symmetry. Despite the known importance of sensorimotor integration for motor recovery, interventions that incorporate RAGT and somatosensory stimuli have been largely overlooked so far. In this paper, we explore how gait symmetry can be restored in healthy subjects following unilateral foot perturbations, using adaptive assistive forces and plantar vibrotactile stimuli provided by a bilateral powered ankle-foot orthosis. Results suggest that combined force feedback and vibrotactile stimuli may be more effective than force feedback alone in reducing spatial asymmetry. Further, force feedback did not produce significant improvements in temporal symmetry, unlike the combined modality. We discuss possible implications of these preliminary findings for future training paradigms for RAGT.

Keywords: New technologies and methodologies in human movement analysis, New technologies and methodologies in biomechanics
Abstract: Simultaneous measurement of muscle activity and rotation around a joint is of significant interest in rehabilitation, but gold-standard methods with optical motion tracking and wireless electromyography recording typically restricts this to the laboratory setting. There has been significant progress using wearable inertial monitoring units (IMUs) for motion tracking, but there are no systems that can easily be deployed to home and provide simultaneous electromyography. We addressed this gap by developing a flexible, wearable, Bluetooth-connected sensor that records both IMU and EMG activity. The sensor runs an efficient quaternion-based complementary filter that estimates the sensor orientation while correcting for estimate drift and constraining magnetometer estimates to only influence heading. The difference in two sensor poses is used to estimate the joint angle, which can be further improved with joint axis estimation. We demonstrate successful tracking of joint angle and muscle activity in a home environment with just the sensors and a smartphone.

Keywords: Biomechanics and robotics in physical rehabilitation, Control strategies in rehabilitation robotics
Abstract: The relationship between the smoothness of the upper limb endpoint movement and multijoint angular motion is a function of the individual joint angular velocities, accelerations, and jerks as well as the instantaneous arm configuration and its rate of change during movement execution. We compared the contribution of jerk components to the total endpoint jerk in able bodied participants who performed arm cranking movements on an arm cranking device where the two arms could crank independently. The results of this investigation suggest that the most dominant components of the end effector jerk are related to both the angular jerks and to the change of arm configuration pose. This jerk partitioning is much stronger as it was found previously for both reaching arm movements and single hand cranking. This shows the task specificity of the decomposition of endpoint jerk and the effect that bi-manual tasks can have on the smoothness of movements. The proposed decomposition may give useful information in why certain bi-manual rehabilitation processes are more useful than others.

Keywords: New technologies and methodologies in biomechanics, Biomechanics and robotics in physical rehabilitation, New technologies and methodologies in human movement analysis
Abstract: Non-invasive in-vivo measurement of individual muscle force is limited by the infeasibility of placing force sensing elements in series with the musculo-tendon structures. While different methods based either on shear wave elastography or electromyography have been recently proposed to noninvasively estimate individual muscle forces, they can only be used to quantify forces in a limited set of superficial muscles. As such, they are not suitable to study the neuromuscular control of movements that require coordinated action of multiple muscles.

In this work, we present multi-muscle magnetic resonance elastography (MM-MRE), a new technique capable of quantifying force for each muscle in the forearm, thus enabling the study of the neuromuscular control of wrist movements. To quantify individual muscle force, MM-MRE integrates measurements of joint torque provided by an MRI-compatible instrumented handle with muscle-specific measurements of shear wave speed obtained via MRE into a forward dynamic muscle force estimator based on a realistic musculoskeletal model of the forearm.

A single-subject pilot experiment demonstrates the possibility of obtaining measurements from individual muscles and establishes that MM-MRE has sufficient sensitivity to detect changes in the muscle specific measurement of shear-wave speed following the application of isometric flexion and extension torques with self-selected intensity.

Keywords: Design and development in rehabilitation robotics, Biomechanics and robotics in physical rehabilitation, Orthotics - modeling and simulation
Abstract: As aging progresses, risk of falls in elderly people increases due to the decreasing the range of motion (RoM) of eversion and the weakening of the plantar flexor. Balance training is performed to reduce the risk of falls and powered ankle-foot orthosis (PAFO) can be utilized in this process. The elderly can conduct training on the narrow roads or on the rugged ground with assistance on rotation of eversion and propulsion by PAFO. However, existing PAFOs were developed just by considering the talocrural joint which make the rotation of sagittal plane of ankle which is called by plantar flexion and dorsiflexion. So, we developed the 2 Degree of Freedom (DoF) PAFO which has the Talocrural and Subtalar joints for frontal plane rotation which is called inversion and eversion. We established the coordinate system and calculated the spatial formulas for talocrural and subtalar joint based on anatomical data. Developed PAFO has the pneumatic artificial muscle (PAM) as an actuator which is controlled by solenoid valve with PWM methods, light-weight 3D printed body and knee orthosis for interfacing with wearer in three area which are thigh, shank and foot. The results of the paper show the validation of design, kinematics and control methods for human experiment.

Keywords: Design and development in rehabilitation robotics, Biomechanics and robotics in physical rehabilitation, Assistive robotics
Abstract: This paper introduces a novel passive wrist bilateral rehabilitation device coupled with a new Virtual Reality (VR) platform. This is the first work to have adapted three-link coaxial spherical parallel manipulator (SPM) to wrist rehabilitation. The device comprises a coaxial SPM and cross-connected cable system. The coaxial SPM facilitates 3 degrees of freedom (DOFs) spherical wrist orientation and singularity-free motion within its workspace. The cross-connected cable system enables bilateral symmetrical exercises in passive mode training. A VR platform with activities of daily living (ADL) task was developed and coupled with the device to increase the adherence of the users to the device. Experiments were conducted with fifteen healthy right-handed individuals with no history of wrist or hand injury to evaluate the feasibility of the system for providing passive bilateral training as well as the effectiveness of the VR platform. Subjects were asked to use their right arms to move the left arms passively through the device to perform four wrist movements, flexion, extension, radial deviation, and ulnar deviation. EMG activations on the left arm were observed when the right arm passively moved the left arm. The results showed that the device was capable of inducing the muscle activation of the left arm and the VR platform increased the motivation to continue the exercises. This demonstrates that this study can serve as the fundamental for larger clinical trials.

Keywords: Design and development in rehabilitation robotics
Abstract: In this paper, we propose a wrist rehabilitation robot employing a novel actuation mechanism composed of electromagnetic clutch, brake, and motor and a safe-related mechanism. The actuation mechanism of the robot can perform both passive and active rehabilitation by the same mechanism. A torque sensor is also coupled to the actuation mechanism so as to measure the wrist joint moment in real-time. For safety an optical indication device is attached to upper position of the robot. User can align his/her wrist joint to the center of rotation with the indication device. Moreover EMG is measured in real-time to evaluate effectiveness of active rehabilitation and to detect an emergency situation such as muscle spasm while doing active rehabilitation. In experiments, the effectiveness of active rehabilitation is evaluated and verified by 3D motion capture data and EMG data measured in real-time. The feasibility of the indication device is evaluated in the wrist joint alignment by verifying X-ray image of wrist and robot. Finally, we performed a usability test with five experts working in medical field, and the test result showed that the proposed robot can be applied to wrist rehabilitation.

Keywords: Design and development in rehabilitation robotics, Assistive robotics - home robots, Biomechanics and robotics in physical rehabilitation
Abstract: A key feature of a successful game is its ability to provide the player with an adequate level of challenge. However, the objective of difficulty adaptation in serious games is not only to maintain the player’s motivation by challenging, but also to ensure the completion of training objectives.

This paper describes our proposed upper-limb rehabilitation game with tangible robots and investigates the effect of game elements and gameplay on the amount of the performed motion in several planes and percentage of failure by using the data from 33 unimpaired subjects who played 53 games within two consecutive days. In order to provide a more generic adaptation strategy in the future, we discretize the game area to circular zones. We then show the effect of changing these zones during gameplay on the activation of different muscles through EMG data in a pilot study.

The study shows that it is possible to increase the challenge level by adding more active agents chasing the player and increasing the speed of these agents. However, only the increase in number of agents significantly increases the users' motion on both planes. Analysis of player behaviors leads us to suggest that by adapting the behaviour of these active agents in specific zones, it is possible to change the trajectory of the user, and to provide a focus on the activation of specific muscles.

Keywords: Design and development in rehabilitation robotics, Biomechanics and robotics in physical rehabilitation, Clinical evaluation in robot-aided rehabilitation
Abstract: This paper describes the design of an Electromyographically(EMG)-driven Neuromuscular Electrical Stimulation (NMES) cycling system. It utilises real-time EMG from actively participating stroke survivors as feedback control to drive the cycling system for rehabilitation. The user controls the speed of the cycling system using muscle activities of the side affected recorded by EMG electrodes. Additionally, adaptable NMES stimulations; also EMG based, were provided in cyclic pattern to the respective muscle groups in order to improve muscle coordination. The targeted muscle groups used to control the system were the Hamstring (HS), Tibialis Anterior (TA), Quadriceps (QC), Gastrocnemius Lateralis (GL) of the leg on the affected side. Using the system, 20 30-minutes sessions were conducted with chronic stroke survivors (n=10) at frequency of 2-4 sessions per week. Clinical assessment scores, namely FMA LE, BBS and 6MWT were calculated before the first session and after the completion of 20 sessions. All the assessment scores showed significant improvement after using the system; FMA LE(P=0.0244), BBS(P=0.0156), 6MWT(P=0.0112), and SI(P=0.0258), showing that the EMG-driven NMES cycling system provides effective rehabilitation for stroke survivors in terms of muscle strength and balance.

Keywords: Design and development in rehabilitation robotics, Robot-aided mobility, Assistive robotics
Abstract: Mobility impairment is becoming a challenging issue around the world with a rapid increase on aging population. Existing tools of walking assistance for mobility-impaired people include passive canes or wheeled rollators which increase energy consumption on the users and disturb the users’ walking rhythm, and powered wheeled chairs which could preclude the muscle activities and accelerate the degeneration of the lower limbs. The research in this paper aiming at helping mobility-impaired people proposes a novel robotic platform with quadrupedal locomotion. With motorized actuation, the quadruped robotic platform could accompany the user at the center and provide protection and possible walking assistance if needed. As the robotic platform is equipped with a leg locomotion, it can enlarge the user’s activity environments, such as both indoor flat floor and outdoor uneven terrain. It can even assist the user to involve in some mobility challenging activities, such as climbing stairs. In this paper, we illustrate the mechanical design of the robotic platform. A continuous gait planning is proposed to create a smooth locomotion for the robot. To quantify the performance, a system-level walking experimentation was conducted, and the results showed that quadruped robotic platform can maintain a statically stability which demonstrate the feasibility and capability of the robotic application for walking assistance.

Keywords: Design and development in rehabilitation robotics, Exoskeletons, Robotic orthoses - design and development
Abstract: Stroke is one of the leading causes of impairment in the world. Many of those who have suffered a stroke experience long-term loss of upper-limb function as a result. BLUE SABINO is an exoskeleton device being developed at the University of Idaho to help assess these patients and aid in their rehabilitation. One of the central design challenges with exoskeletons is limiting the overall weight of the device. Motors used in actuation of these devices are often oversized to allow gravity balancing of the device and user and the creation of torques to facilitate patient movements. If the torques required for gravity balancing are achieved through elastic elements, the motor and other upstream components can be lighter, potentially greatly reducing the overall weight of the device. In this paper, constant-force springs may provide an effective method of generating a constant offsetting torque to compensate for gravity. In experimental testing of multiple mounting configurations of C-shaped constant-force springs (single, backto-back, double-wrapped), the force output fluctuated less than 8.6% over 180° of wrapping, with friction values below 2.6%, validating the viability of constant-force springs for this application. The results suggest the back-to-back configuration provides a simpler implementation with better force consistency while the double-wrapped configuration adds less friction to the system.

Keywords: Design and development in rehabilitation robotics, Control strategies in rehabilitation robotics, Biomechanics and robotics in physical rehabilitation
Abstract: Low impedance and torque control are critical for movement rehabilitation using robotic exoskeletons. A grounded 3 degree of freedom shoulder exoskeleton was designed for movement assistance in shoulder abduction/adduction, flexion/extension, and shoulder internal/external rotation. Two series elastic actuators designs were developed using a linear spring arrangement with a global nonlinear stiffness behavior. RMS errors during application of constant torque were less than .06 Nm in shoulder add/abd and less than .04 Nm in arm rotation as the limb was moved in sinusoidal trajectories up to 3.5 Hz. For abd/adduction, the step response rise time was .05 s, and free mode impedance peaked at .007 Nm/deg during 3.5 Hz oscillations. For arm rotation, the step response rise time was .03 s, and impedance peaked at .023 Nm/deg during 3.5 Hz oscillations. Both SEA designs had performance measurements that were similar to other SEA designs in terms of torque tracking, but with much lower impedance than previously reported.

Keywords: Design and development in rehabilitation robotics, Assistive robotics, Robot-aided mobility
Abstract: Over the past decade, many medical lower limb exoskeletons have been developed and exploited. The advantage of such a system is to ensure the mobility of paraplegic patients, as well as their rehabilitation. However, existing solutions have not been widely available among the disabled population, particularly adolescents, due to the limitations of their conception caused by the rapid physical growth and morphological variation of this population.

In this paper, a new scalable structure of the exoskeleton is proposed as a feasible solution to the problem of morphological changes. As this is the first time the generic term "scalability" has been used, its requirements and design methods, including the morphological changes and alignment, are presented in detail to better meet the growing needs for such a promising device. The evaluation of the proposed scalable structure shows a promising utility that is illustrated by several experimental scenarios: the load capacity of the structure, the efficiency of the fixation mechanisms, the validation of the hip alignment mechanism and finally the validation of the evolutionary structure.

Keywords: Design and development in rehabilitation robotics, Exoskeletons
Abstract: This paper presents a Transmissive Force Sensing Elastic Actuator (TFSEA) for exoskeleton applications. Exoskeletons can serve as orthotic or rehabilitative devices enabling people with paraplegia to walk. Several exoskeletons have been commercialized, most of which are above 23 kg, making them too heavy and bulky for people with paraplegia to put on and take off by themselves. One of the bottlenecks of achieving lightweight exoskeleton design is actuation. This work focused on developing a compact, lightweight and high-performance actuator. Using the differential property of harmonic drive, a new elastic actuator configuration was created. A dynamic model was developed for the proposed design and a model-based controller was implemented. Various tests were done to evaluate the performance of the actuator. The results showed that the torsional spring exhibits linearity of 99.99%, with no backlash or hysteresis. The joint can output 100 Nm peak torque with a large-torque bandwidth of 5 Hz. Moreover, it weighs only 1.56 kg, leading to a torque density of 64 Nm/kg and a power density of 360 W/kg, the highest published to date in the same torque and power rating.

Keywords: Design and development in rehabilitation robotics, Control strategies in rehabilitation robotics, Assistive robotics
Abstract: This paper presents the development of a pneumatically actuated soft robotic based bilateral therapy system for hand rehabilitation in post-stroke patients. The goal is to use a healthy hand to guide the motion of the paretic hand using a sensorized glove and a robotic exoskeleton, respectively. The sensorized glove tracks the motion of the healthy hand and provides inputs for the soft robotic hand exoskeleton to apply mimicking motion to the paretic hand. Two control algorithms, PD flow-based and adaptive PD pressure-based position controls, were developed and tested. Initial tests confirmed the ability of the systems to apply bilateral therapy. Furthermore, the adaptive pressure-based controller showed better performance with overall error reduced by 25.8% with respect to the flow-based controller. Future studies will include feasibility and performance of the system for applying therapy to post-stroke patients.

Keywords: Design and development in rehabilitation robotics, Clinical evaluation in robot-aided rehabilitation, Biomechanics and robotics in physical rehabilitation
Abstract: The brain injury that results in cerebral palsy CP may adversely affect fine motor control of the hand. The degradation of manual dexterity in the fingers profoundly impacts overall functionality of the upper limb, yet research efforts to facilitate rehabilitation of finger individuation in children with CP have been limited. This study describes the development of an integrated hardware and software platform for training and evaluating finger individuation. A pneumatically actuated glove provides extension assistance or flexion resistance independently to each digit in concert with playing a virtual reality keyboard. This setup enables intensive and efficient practice of fine motor control of either or both hands. Bimanual training options range from mirror movements to fully independent motions and rhythms in each hand, thereby enabling maintenance of the proper level of challenge. Additionally, an instrument was created to provide assessment of individuated fingertip force generation in order to evaluate effectiveness of the training. Preliminary data were obtained from children both with and without CP using this tool.

Keywords: Biomechanics and robotics in physical rehabilitation, Design and development in rehabilitation robotics
Abstract: Body weight support (BWS) system is widely used for patients to help their gait training. However, that existing systems require large workspace and elastic component in actuation makes the systems inappropriate for wide clinical use. The interactive treadmill was reported to be cost/space effectively simulate overground walking, but there was no suitable BWS system for the treadmill. We proposed a new concept of body weight support system for interactive treadmill. For wide clinical use, we applied a two-wire driven mechanism with simple actuator and a custom pelvic-type harness. With three healthy subjects, the performance of the proposed BWS system on unloading force control was evaluated, and the result showed that the feasibility of the proposed BWS system.

Keywords: Robotic orthoses - design and development, Design and development in rehabilitation robotics, Wearable robotic systems
Abstract: In previous research, we have developed a high-dorsiflexion assistive robotic technology aiming for gait rehabilitation targeting on ankle dorsiflexion movement. A McKibben-type artificial muscle is applied to provide large dorsiflexion force while adding little weight to the device. This ensures the foot clearance before initial stance phase in gait. Meanwhile, a tension spring is deployed in series with the artificial muscle to support heel rocker function in loading response phase. Suitable spring coefficient for each individual differs according to ankle’s dorsiflexion torque in loading response. An unsuitable spring would lead to knee deviation in this phase. In this study, we derived an identification equation to determine a suitable spring coefficient for individuals based on estimation of dorsiflexion torque required to support. An evaluation test on healthy objects was conducted, which shows no negative effects on participants’ knee angles with the identified spring coefficient.

Keywords: Design and development in rehabilitation robotics, Biomechanics and robotics in physical rehabilitation, Robot-aided mobility
Abstract: The research and development of wearable robotic devices has been accelerated by off-board control and actuation systems. While off-board robotic actuation systems provide many benefits, the impedance at the robotic joint is often high. High joint impedance is undesirable for wearable devices like exoskeletons, as the user is unable to move their joint without actively controlled motion from the motors. We propose that the impedance can be reduced substantially in off-board robotic actuation systems by minimizing the reflected inertia from the motor. We have developed a model and optimization-based methodology for selecting a motor and set of mechanical design parameters that minimize reflected inertia. This methodology was implemented in the design of an off-board knee exoskeleton as a case study. A grey-box model was developed that incorporates biomechanical knee trajectories, an experimentally determined human-device interface stiffness model, Bowden cable stiffness and friction, and a motor model. A constrained optimization routine was developed that uses the model and a library of 157 candidate servo motors to select the actuator and mechanical design parameters that minimize reflected inertia at the exoskeleton joint. We found that 86 of the motors were able to carry out the necessary torque-velocity trajectories to achieve the prescribed exoskeleton joint torques and limb motions.

Keywords: Design and development in rehabilitation robotics, Wearable robotic systems, Exoskeletons
Abstract: A new type of actuator made from twisting a silver-plated nylon thread presents new possibilities for the design of wearable mechatronic rehabilitation devices. The twisted coiled actuator (TCA) has been previously shown to provide a power density up to 100 times that of biological muscles, while encompassing biomimetic characteristics. However, since TCAs require heat to contract, the main drawbacks preventing this type of actuator are its inherent low efficiency and slow reaction times. To combat both of these issues, a simple tube enclosure was designed to provide active cooling using forced air. The two main parameters affecting the efficiency and bandwidth are the cooling air pressure and tube diameter. This study presents a two-way repeated measures test to compare these parameters on the cooling and heating rates of the TCA system, as well as the thermal capacitance with three pressure levels (10, 15, and 20 psi) and three tube diameters (4, 4.5, and 5 mm). The results show that an increase in pressure significantly improves the rate of cooling, while a decrease in tube diameter has negative effects on the efficiency and cooling rate of the system. The mean values of the cooling time (cool) were 2.972, 2.210, and 2.682 seconds for 4, 4.5, and 5 mm diameters, respectively. These results indicate that a decrease in diameter improves the cooling rate up to the point at which the walls of the tube become so close to the TCA strand, that they prevent rapid heat transfer.

Keywords: Design and development in rehabilitation robotics, Robotic orthoses - design and development, Exoskeletons
Abstract: Knee osteoarthritis patients have pain in their knee and it can become difficult to walk depending on the progress of symptoms. After performing chondrocyte implantation, it is necessary to reduce the load on the knee joint until the implanted cartilage is integrated. The purposes of this study were to develop a device that enables the user to walk and reduced the weight on the knee joint and to confirm basic performance of the device through experiments. The device was composed of a seat for supporting the body weight of the user, a prosthetic knee, and the floor reaction force sensor shoes. Experiments were conducted to confirm the basic performance of the device. As a result, an able-bodied participant who wore the device was able to walk while unloading two-thirds of their body weight onto their knee. As a result of gait analysis, it was found that the gait did not change significantly even when the device was worn.

Keywords: Robotic prostheses - neural interfaces, Robotic prostheses - design and development
Abstract: Soft robotic fingers have shown great potential for use in prostheses due to their inherent compliant, light, and dexterous nature. Recent advancements in sensor technology for soft robotic systems showcase their ability to perceive and respond to static cues. However, most of the soft fingers for use in prosthetic applications are not equipped with sensors which have the ability to perceive texture like humans can. In this work, we present a dexterous, soft, biomimetic solution which is capable of discrimination of textures. We fabricated a soft finger with two individually controllable degrees of freedom with a tactile sensor embedded at the fingertip. The output of the tac- tile sensor, as texture plates were palpated, was converted into spikes, mimicking the behavior of a biological mechanoreceptor. We explored the spatial properties of the textures captured in the form of spiking patterns by generating spatial event plots and analyzing the similarity between spike trains generated for each texture. Unique features representative of the different textures were then extracted from the spikes and input to a classifier. The textures were successfully classified with an accuracy of 94% when palpating at a rate of 42 mm/s. This work demonstrates the potential of providing amputees with a soft finger with sensing capabilities, which could potentially help discriminate between different objects and surfaces during activities of daily living (ADL) through palpation.

Keywords: Robotic prostheses - neural interfaces
Abstract: Although more multi-articulating hand prostheses have become commercially available, replacing a missing hand remains challenging from a control perspective. This study investigated myoelectric direct control and pattern recognition home use of a multi-articulating hand prosthesis for individuals with a transradial amputation. Four participants were fitted with an i-limb Ultra Revolution hand and provided training for each control style and on how to use the various grips. The number of grips available to each individual was determined by clinician and user feedback to optimize both the number of grips available and the reliability of grip selection. Home trial data corresponding to individual usage were recorded. No significant differences were found between direct and pattern recognition control home trials in regards to trial length (p=0.96), days powered on (p=0.21), or total time powered on (p=0.91). There was a higher average number of configured grips for direct control at 4.8 [0.5] compared to 3.8 [0.5] for pattern recognition control, but this difference did not reach significance (p=0.092). Across all hand close movements, users spent a majority of time (> 80%) in one grip when using direct control. For pattern recognition usage was spread across more grips (> 45% time in one grip, 25% time in a 2nd grip, and 20% time in a 3rd grip). Pattern recognition control may provide users with a more intuitive way to select and use the various grips available to them.

Keywords: New technologies and methodologies in human movement analysis, Robotic prostheses - design and development, Robotic prostheses - modeling and simulation
Abstract: Assessing upper limb prostheses and their influence when performing goal-directed activities is essential to compare the quality of different devices and optimize their control settings. Currently available assessments are often subjective, insensitive, and cannot provide a detailed evaluation of prostheses and their usage. The goal of this pilot study was to explore the feasibility of using the Virtual Peg Insertion Test (VPIT) to provide an in-depth assessment of a prosthesis and its functional performance. One transradial amputee performed the goal-directed manipulation task of the VPIT with the sound body side and four different myoelectrically-controlled prostheses. The subject was able to complete the VPIT protocol successfully with technically advanced prosthesis (two out of four devices). The kinematic- and kinetic-based objective evaluation measures extracted from the VPIT were able to capture clear differences between the sound and amputated body side and were able to identify varying movement patterns for different prostheses. Additionally, the outcome measures were sensitive to changes in prosthesis control settings and showed clear trends across measures of subjectively perceived prosthesis quality assessed through a questionnaire. This work demonstrates the general feasibility of objectively evaluating functional prosthesis usage with the VPIT.

Keywords: Robotic prostheses - design and development
Abstract: Myoelectric control systems for assistive devices are still unreliable. The user's input signals can become unstable over time due to e.g. fatigue, electrode displacement, or sweat. Hence, such controllers need to be constantly updated and heavily rely on user feedback. In this paper, we present an automatic failure detection method which learns when plausible predictions become unreliable and model updates are necessary. Our key insight is to enhance the control system with a set of generative models that learn sensible behaviour for a desired task from human demonstration. We illustrate our approach on a grasping scenario in Virtual Reality, in which the user is asked to grasp a bottle on a table. From demonstration our model learns the reach-to-grasp motion from a resting position to two grasps (power grasp and tridigital grasp) and how to predict the most adequate grasp from local context, e.g. tridigital grasp on the bottle cap or around the bottleneck. By measuring the error between new grasp attempts and the model prediction, the system can effectively detect which input commands do not reflect the user’s intention. We evaluated our model in two cases: i) with both position and rotation information of the wrist pose, and ii) with only rotational information. Our results show that our approach detects statistically highly significant differences in error distributions with p<0.001 between successful and failed grasp attempts in both cases.

Keywords: Robotic prostheses - modeling and simulation, Control strategies in rehabilitation robotics
Abstract: In the recent years important steps forward have been made in the field of signal processing on muscle signals for hand prosthetics control. At the state of the art different algorithms and techniques allow a precise estimation of hand movements. However, they mostly work exclusively on the electrode space, not seeking for any information about the currents on the contracted muscles. In this study we propose a novel simplified method to estimate the muscles currents in the forearm, along with a first experimental application on two simple movements to assess its performance. We modeled the signal propagation from muscles to electrodes using a purely resistive electrical networks and afterwards apply the graph theory to assess the muscle currents. It considerably simplify the estimation of muscle’s current, decreasing the problem complexity, and therefore potentially it can be a suitable approach for future prosthetics’ control.

Keywords: Robotic prostheses - design and development, Assistive robotics, Wearable robotic systems
Abstract: Over the last decade, active lower-limb prostheses demonstrated their ability to restore a physiological gait for transfemoral amputees by supplying the required positive energy balance during daily life locomotion activities. However, the added-value of such devices is significantly impacted by their limited energetic autonomy, excessive weight and cost preventing their full appropriation by the users. There is thus a strong incentive to produce active yet affordable, lightweight and energy efficient devices. To address these issues, we developed the ELSA (Efficient Lockable Spring Ankle) prosthesis embedding both a lockable parallel spring and a series elastic actuator, tailored to the walking dynamics of a sound ankle. The first contribution of this paper concerns the developement of a bio-inspired, lightweight and stiffness adjustable parallel spring, comprising an energy efficient ratchet and pawl mechanism with servo actuation. The second contribution is the addition of a complementary rope-driven series elastic actuator to generate the active push-off. The system produces a sound ankle torque pattern during flat ground walking. Up to 50% of the peak torque is generated passively at a negligible energetic cost (0.1 J/stride). By design, the total system is lightweight (1.2 kg) and low cost.

Keywords: Design and development in rehabilitation robotics, Assistive robotics, Control strategies in rehabilitation robotics
Abstract: This article describes the motivation behind and the technical aspects at the basis of the development of the innovative rehabilitation robot hunova®. The paper describes in detail the hardware and software design of the system and summarizes the clinical studies carried out to validate the technology.

Keywords: Design and development in rehabilitation robotics, Assistive robotics, Biomechanics and robotics in physical rehabilitation
Abstract: In the past few years, several exosuits for upper extremity assistance have been developed. The design of exosuits is often based on a bio-mimetic design approach. However, in the design process, the interactions of movement directions during daily living tasks have not yet been analyzed comprehensively. Therefore, the designs of exosuits might be overly complex, as movement directions that are coupled during daily life tasks were implemented independently; or lack functionality, as relevant movement directions were disregarded. In the meta-analysis presented in this paper, the maximum angles occurring during daily living tasks in the upper extremity of unimpaired individuals were examined. To identify kinematic couplings between joint axes, the interactions between movement directions acting against gravity were analyzed. The strongest correlations were found between rotation in the plane of elevation and humeral axial rotation (R2=0.82, p<0.001), and between humeral elevation and humeral axial rotation (R2=0.16, p=0.001). Shoulder rotations and elbow flexion were not correlated. We conclude that humeral axial rotation is a relevant movement direction in the upper extremity, which, so far, has often been neglected. To simplify the design of exosuits, we propose a one degree of freedom support trajectory in which rotation in the plane of elevation (at -70° and 80°) and humeral axial rotation (at 110° and -60°) are coupled to humeral elevation (continuously from -40° to -110°)

Keywords: Design and development in rehabilitation robotics, Biomechanics and robotics in physical rehabilitation, Robotic platforms in neuroscience
Abstract: In an attempt to promote greater functional recovery after spinal cord injury, researchers have begun exploring combinatorial treatments, such as robotic rehabilitation combined with stem cell transplantation. Since these treatment methods are in their nascent stages, rodent models have been proposed for initial investigations. Robots have been built for locomotion rehabilitation and planar forelimb reach and grasp assessment with rodents; however, a robotic platform suitable for three-dimensional movement rehabilitation of the rodent forelimb has not yet been developed. In this paper, a novel three degree of freedom robotic manipulator for automated forelimb rehabilitation combined with stem cell transplantation after cervical spinal cord injury with rats is proposed. The robot interfaces with a rat in an end-effector manner, measuring and interacting with the forelimb in the 3D Cartesian space. In this work, we trained two rats through behavioral shaping to actively interact with the device during two robot control modes. This work provides preliminary investigations into the feasibility of 3D forelimb rehabilitation with rats, which could be translated as a paradigm for combinatorial treatments after spinal cord injury in a controlled manner.

Keywords: Assistive robotics - home robots
Abstract: An important challenge for technology-assisted self-led rehabilitation is how to automate appropriate schedules of exercise that are responsive to patients' needs, and optimal for learning. While random scheduling has been found to be superior for long-term learning relative to fixed scheduling (Contextual Interference), this method is limited by not adequately accounting for task difficulty, or skill acquisition during training. One method that combines contextual interference with adaptation of the challenge to the skill-level of the player is Challenge Point Framework (CPF) theory. In this pilot study we test whether self-led motor training based upon CPF scheduling achieves faster learning than deterministic, fixed scheduling. Training was implemented in a mobile gaming device adapted for arm disability, allowing for grip and wrist exercises. We tested 11 healthy volunteers and 12 hemiplegic stroke patients in a single-blinded no crossover controlled randomized trial. Results suggest that patients training with CPF-based adaption performed better than those training with fixed conditions. This was not seen for healthy volunteers whose performance was close to ceiling. Further data collection is required to determine the significance of the results.

Keywords: Design and development in rehabilitation robotics, New technologies and methodologies in human movement analysis, Integrated diagnostic and therapeutic systems
Abstract: Hand function is often impaired after neurological injuries such as stroke. In order to design patient-specific rehabilitation, it is essential to quantitatively assess those deficits. Current clinical scores cannot provide the required level of detail, and most assessment devices have been developed for the proximal joints of the upper limb. This paper presents a new robotic platform for the assessment of proprioceptive, motor, and sensorimotor hand impairments. A detailed technical evaluation demonstrated the capabilities to render different haptic environments required for a comprehensive assessment battery. A preliminary study on proprioceptive assessment using a gauge position matching task with one healthy, one stroke, and one multiple sclerosis subject showed that the robotic system is able to reveal proprioceptive deficits, is suitable for interaction due to its ergonomic design, and has the potential to be integrated into the clinical settings.

Keywords: Design and development in rehabilitation robotics, Biomechanics and robotics in physical rehabilitation
Abstract: Accurately judging one's self-generated forces is integral to seamlessly controlling movements during everyday life. Individuals post-hemiparetic stroke have impairments when matching forces between arms; this impairment may make activities as simple as carrying a tray challenging. As such, we developed a training protocol for use by individuals with stroke to improve their accuracy in judging the torques that they generate. We tested its feasibility in six individuals without neurological impairments. Participants interacted with an instrumented isometric device at each arm and received automated audiovisual cues in response to the torques that they generated about each elbow joint. The participant's task was to keep a launched ball on its planned course. This was achieved by sequentially applying required elbow torques at the correct times to close a left flap using the left arm and a right flap using the right arm. Participants performed this task 20 times when initiating with their left arm and 20 times with their right arm. All participants had a success rate in the range of 60-80% regardless of the arm dominance of the leading arm. Also, all participants anecdotally reported the game to be intuitive and provided an average difficulty rating that indicated the task was relatively easy to learn (i.e., 3 out 10). We conclude that the game may be suitable, enjoyable, and motivational for training coordination of torques between arms in individuals with stroke.