Just noticeable differences for elbow joint torque feedback.

Joint torque feedback is a new and promising means of kinesthetic feedback imposed by a wearable device. The torque feedback provides the wearer temporal and spatial information during a motion task. Nevertheless, little research has been conducted on quantifying the psychophysical parameters of how well humans can perceive external torques under various joint conditions. This study aims to investigate the just noticeable difference (JND) perceptual ability of the elbow joint to joint torques. The paper focuses on the ability of two primary joint proprioceptors, the Golgi-tendon organ (GTO) and muscle spindle (MS), to detect elbow torques, since touch and pressure sensors were masked. We studied 14 subjects while the arm was isometrically contracted (static condition) and was moving at a constant speed (dynamic condition). In total there were 10 joint conditions investigated, which varied the direction of the arm's movement and the preload direction as well as torque direction. The JND torques under static conditions ranged from 0.097 Nm with no preload to 0.197 Nm with a preload of 1.28 Nm. The maximum dynamic JND torques were 0.799 Nm and 0.428 Nm, when the arm was flexing and extending at 213 degrees per second, respectively.

Exoskeleton home and community use in people with complete spinal cord injury.

A consequence of a complete spinal cord injury (SCI) is the loss of gait capacity. Wearable exoskeletons for the lower extremity enable household and community ambulation in people with SCI. This study assessed the amount, purpose, and location of exoskeleton use in the home and community environment, without any restrictions. The number of steps taken was read from the exoskeleton software. Participants kept a daily logbook, and completed two user experience questionnaires (Quebec User Evaluation of Satisfaction with assistive Technology (D-QUEST) and System Usability Scale (SUS)). Fourteen people with a complete SCI used the ReWalk exoskeleton a median of 9 (range [1-15]) out of 16 ([12-21]) days, in which participants took a median of 3,226 ([330-28,882]) steps. The exoskeleton was mostly used for exercise purposes (74%) and social interaction (20%). The main location of use was outdoors (48%). Overall, participants were satisfied with the exoskeleton (D-QUEST 3.7 ± 0.4) and its usability (SUS 72.5 [52.5-95.0]). Participants with complete SCI report satisfaction with the exoskeleton for exercise and social interaction in the home and community, but report limitations as an assistive device during daily life.

Dropped Head Syndrome Attenuation by Hybrid Assistive Limb: A Preliminary Study of Three Cases on Cervical Alignment during Walking.

Background and Objectives: Dropped head syndrome (DHS) is characterized by apparent neck extensor muscle weakness and difficulty in extending the neck to raise the head against gravity. DHS affects forward vision and eating behavior, and hence impairs quality of life. However, standardized treatment of DHS has not yet been established. The purpose of this preliminary study is to seek for a possibility of effective non-surgical, conservative treatment for DHS, by applying a robotic treatment. Materials and Methods: A wearable exoskeleton type robot suit hybrid assistive limb (HAL) was applied to three patients with DHS. A course of HAL treatment included 10 sessions of gait training using HAL. One session lasted about an hour. Case 1 completed the course twice, the first time in two weeks (one session per day) and second time in 10 months (one session per month). Case 2 and Case 3 completed the course once in 10 weeks (one session per week) and in 6 months (one session per 2.5 weeks), respectively. Immediate and lasting effects of HAL on the reduction of cervical sagittal vertical alignment (SVA) during gait was evaluated using a motion capture system. Results: Case 1 showed improvement of cervical alignment during gait after the HAL courses of both different frequencies. Case 2 did not show improvement of cervical alignment during gait. Case 3 showed improvement of cervical kyphosis but not of cervical sagittal alignment during gait. Conclusions: The results of the preliminary study suggest that gait training using HAL may be an effective option of conservative treatment for a part of DHS patients. They also suggest that a lack of immediate effects on the cervical alignment and a lack of ability to perform compensatory trunk motion may indicate a non-responding patient. Generalization of the results requires further research with more cases.

Clinical Outcomes with the Intrepid Dynamic Exoskeletal Orthosis: A Retrospective Analysis.

INTRODUCTION: Severe lower limb injuries have a negative impact on many aspects of an individual's life. One rehabilitative option for patients who have undergone limb salvage is the Intrepid Dynamic Exoskeletal Orthosis (IDEO). The IDEO is a custom-made dynamic response device which is used to restore function for patients with a wide variety of injuries. Clinical outcomes were routinely collected on patients fit with IDEOs at the Center for the Intrepid, Brooke Army Medical Center. The purpose of this retrospective study was to analyze the clinical outcomes collection process and the patient outcomes collected as part of routine clinical care. METHODS: The Brooke Army Medical Center IRB approved this study and granted waivers of informed consent and HIPAA authorization. Electronic medical records were reviewed over an 18-month period from July 2014 to January 2016. Records were examined to obtain the date of IDEO delivery, date of outcomes form completion, responses on the forms, and to verify diagnosis or injury. Data gathered included wear time, IDEO comfort, pain with and without the IDEO, Lower Extremity Functional Scale scores with and without the IDEO, and global rating of change questions for everyday activities and high impact activities. Wilcoxon signed-ranked tests were used to compare pain and function with vs. without the IDEO. RESULTS: During the 18-month period, new IDEOs were delivered to 156 unique patients. Outcomes forms were collected as part of routine clinical care from 90 of these 156 patients (58%). An additional nine forms were collected from patients who received their IDEOs prior to July 2014. In all, 99 outcomes forms were collected. Mean follow-up time from IDEO delivery to outcomes form completion was 35 ± 31 days for the original 90 patients. The most common patient diagnoses were fracture, nerve injury, arthritis, and fusion. Responses on the forms indicated that patients were generally comfortable wearing their IDEOs (8.3 ± 1.3 on a 0-10 scale) and wore them most of the day (10.7 ± 3.4 hours per day). Improvement in pain (from 5.2 ± 2.9 to 1.7 ± 1.6 points on a 0-10 scale) and Lower Extremity Functional Scale scores (from 29.7 ± 16.6 to 59.5 ± 13.6 points) with the IDEO were both more than the minimal clinically important difference and were statistically significant (p < 0.001). CONCLUSION: This descriptive retrospective study demonstrated that it was feasible to collect clinical outcomes data which were relevant for characterizing the effects of IDEO use and enabled quantification of improvements in self-reported function and walking pain with the IDEO. Due to the retrospective nature of this study, limitations include missing data and the lack of any performance measures to complement the self-reported data. Clinical outcomes collection continues as a routine part of clinical care and there remains an ongoing aim to collect information on all patients to obtain an accurate assessment of devices and services and ultimately better serve our patients.

Exoskeleton gait training after spinal cord injury: An exploratory study on secondary health conditions.

OBJECTIVE: To explore changes in pain, spasticity, range of motion, activities of daily living, bowel and lower urinary tract function and quality of life of individuals with spinal cord injury following robotic exoskeleton gait training. DESIGN: Prospective, observational, open-label multicentre study. METHODS: Three training sessions per week for 8 weeks using an Ekso™ GT robotic exoskeleton (EKSO Bionics). Included were individuals with recent (<1 year) or chronic (>1 year) injury, paraplegia and tetraplegia, complete and incomplete injury, men and women. RESULTS: Fifty-two participants completed the training protocol. Pain was reported by 52% of participants during the week prior to training and 17% during training, but no change occurred longitudinally. Spasticity decreased after a training session compared with before the training session (p <0.001), but not longitudinally. Chronically injured participants increased Spinal Cord Independence Measure (SCIM III) from 73 to 74 (p = 0.008) and improved life satisfaction (p = 0.036) over 8 weeks of training. Recently injured participants increased SCIM III from 62 to 70 (p < 0.001), but no significant change occurred in life satisfaction. Range of motion, bowel and lower urinary function did not change over time. CONCLUSION: Training seemed not to provoke new pain. Spasticity decreased after a single training session. SCIM III and quality of life increased longitudinally for subsets of participants.

Lower limb sagittal kinematic and kinetic modeling of very slow walking for gait trajectory scaling.

Lower extremity powered exoskeletons (LEPE) are an emerging technology that assists people with lower-limb paralysis. LEPE for people with complete spinal cord injury walk at very slow speeds, below 0.5m/s. For the able-bodied population, very slow walking uses different neuromuscular, locomotor, postural, and dynamic balance control. Speed dependent kinetic and kinematic regression equations in the literature could be used for very slow walking LEPE trajectory scaling; however, kinematic and kinetic information at walking speeds below 0.5 m/s is lacking. Scaling LEPE trajectories using current reference equations may be inaccurate because these equations were produced from faster than real-world LEPE walking speeds. An improved understanding of how able-bodied people biomechanically adapt to very slow walking will provide LEPE developers with more accurate models to predict and scale LEPE gait trajectories. Full body motion capture data were collected from 30 healthy adults while walking on an instrumented self-paced treadmill, within a CAREN-Extended virtual reality environment. Kinematic and kinetic data were collected for 0.2 m/s-0.8 m/s, and self-selected walking speed. Thirty-three common sagittal kinematic and kinetic gait parameters were identified from motion capture data and inverse dynamics. Gait parameter relationships to walking speed, cadence, and stride length were determined with linear and quadratic (second and third order) regression. For parameters with a non-linear relationship with speed, cadence, or stride-length, linear regressions were used to determine if a consistent inflection occurred for faster and slower walking speeds. Group mean equations were applied to each participant's data to determine the best performing equations for calculating important peak sagittal kinematic and kinetic gait parameters. Quadratic models based on walking speed had the strongest correlations with sagittal kinematic and kinetic gait parameters, with kinetic parameters having the better results. The lack of a consistent inflection point indicated that the kinematic and kinetic gait strategies did not change at very slow gait speeds. This research showed stronger associations with speed and gait parameters then previous studies, and provided more accurate regression equations for gait parameters at very slow walking speeds that can be used for LEPE joint trajectory development.

Exoskeleton robot control for synchronous walking assistance in repetitive manual handling works based on dual unscented Kalman filter.

Prolong walking is a notable risk factor for work-related lower-limb disorders (WRLLD) in industries such as agriculture, construction, service profession, healthcare and retail works. It is one of the common causes of lower limb fatigue or muscular exhaustion leading to poor balance and fall. Exoskeleton technology is seen as a modern strategy to assist worker's in these professions to minimize or eliminate the risk of WRLLDs. Exoskeleton has potentials to benefit workers in prolong walking (amongst others) by augmenting their strength, increasing their endurance, and minimizing high muscular activation, resulting in overall work efficiency and productivity. Controlling exoskeleton to achieve this purpose for able-bodied personnel without impeding their natural movement is, however, challenging. In this study, we propose a control strategy that integrates a Dual Unscented Kalman Filter (DUKF) for trajectory generation/prediction of the spatio-temporal features of human walking (i.e. joint position, and velocity, and acceleration) and an impedance cum supervisory controller to enable the exoskeleton to follow this trajectory to synchronize with the human walking. Experiment is conducted with four subjects carrying a load and walking at their normal speed- a typical scenario in industries. EMG signals taken at two muscles: Right Vastus Intermedius (on the thigh) and Right Gastrocnemius (on the calf) indicated reduction in muscular activation during the experiment. The results also show the ability of the control system to predict spatio-temporal features of the pilots' walking and to enable the exoskeleton to move in concert with the pilot.

Wearable robotic exoskeleton for overground gait training in sub-acute and chronic hemiparetic stroke patients: preliminary results.

BACKGROUND: Recovery of therapeutic or functional ambulatory capacity in post-stroke patients is a primary goal of rehabilitation. Wearable powered exoskeletons allow patients with gait dysfunctions to perform over-ground gait training, even immediately after the acute event. AIM: To investigate the feasibility and the clinical effects of an over-ground walking training with a wearable powered exoskeleton in sub-acute and chronic stroke patients. DESIGN: Prospective, pilot pre-post, open label, non-randomized experimental study. SETTING: A single neurological rehabilitation center for inpatients and outpatients. POPULATION: Twenty-three post-stroke patients were enrolled: 12 sub-acute (mean age: 43.8±13.3 years, 5 male and 7 female, 7 right hemiparesis and 5 left hemiparesis) and 11 chronic (mean age: 55.5±15.9 years, 7 male and 4 female, 4 right hemiparesis and 7 left hemiparesis) patients. METHODS: Patients underwent 12 sessions (60 min/session, 3 times/week) of walking rehabilitation training using Ekso™, a wearable bionic suit that enables individuals with lower extremity disabilities and minimal forearm strength to stand up, sit down and walk over a flat hard surface with a full weight-bearing reciprocal gait. Clinical evaluations were performed at the beginning of the training period (t0), after 6 sessions (t1) and after 12 sessions (t2) and were based on the Ashworth scale, Motricity Index, Trunk Control Test, Functional Ambulation Scale, 10-Meter Walking Test, 6-Minute Walking Test, and Walking Handicap Scale. Wilcoxon's test (P<0.05) was used to detect significant changes. RESULTS: Statistically significant improvements were observed at the three assessment periods for both groups in Motricity Index, Functional Ambulation Scale, 10-meter walking test, and 6-minute walking test. Sub-acute patients achieved statistically significant improvement in Trunk Control Test and Walking Handicap Scale at t0-t2. Sub-acute and chronic patient did not achieve significant improvement in Ashworth scale at t0-t2. CONCLUSIONS: Twelve sessions of over-ground gait training using a powered wearable robotic exoskeleton improved ambulatory functions in sub-acute and chronic post-stroke patients. Large, randomized multicenter studies are needed to confirm these preliminary data. CLINICAL REHABILITATION IMPACT: To plan a completely new individual tailored robotic rehabilitation strategy after stroke, including task-oriented over-ground gait training.

Effect on body composition and bone mineral density of walking with a robotic exoskeleton in adults with chronic spinal cord injury.

OBJECTIVE: To examine the effect on body composition and bone mineral density of locomotor training using a robotic exoskeleton in individuals with spinal cord injury. STUDY DESIGN: Interventional study. SUBJECTS/METHODS: Five adults with a non-progressive traumatic complete sensorimotor spinal cord injury who were using a wheelchair as a primary mode of mobility. Participants performed a personalized 6-week progressive locomotor training programme using a robotic exoskeleton 3 times/week for up to 60 min. Body composition measures were determined using dual energy X-ray absorptiometry and peripheral quantitative computed tomography. RESULTS: A significant increase in leg and appendicular lean body mass and a decrease in total, leg and appendicular fat mass was observed after the intervention. Furthermore, the calf muscle cross-sectional area increased significantly after the intervention. Finally, although not statistically significant, there was an increase of 14.5% in bone mineral density of the tibia, which may be clinically significant. A decrease of > 5 % was also noted for subcutaneous adipose tissue and intramuscular adipose tissue. CONCLUSION: Locomotor training using a robotic exoskeleton appears to be associated with improvements in body composition and, potentially, bone health.

Trunk muscle activity patterns in a person with spinal cord injury walking with different un-powered exoskeletons: A case study.

OBJECTIVE: To investigate trunk muscle activity patterns in a person with thoracic spinal cord injury when walking with different un-powered exoskeletons, and to explore how different un-powered exoskeletons affect trunk muscle activity patterns. CASE REPORT: Data were recorded from a subject with complete spinal cord injury at T10, using an electromyography system on 4 pairs of trunk muscles and a motion capture system simultaneously. RESULTS: The participant generated large muscle force to laterally bend and rotate trunk, and swung his leg through the moments generated, not only by trunk flexion and extension, but by trunk rotation. In an energy-stored exoskeleton without springs condition, the energy generated by erector spinae contraction was stored in the energy-stored component in the stance phase and released in the swing phase to compensate for energy generated by the obliquus externus abdominis and avoid overuse of the obliquus externus abdominis. CONCLUSION: These findings prompt further development of un-powered exoskeletons and investigation into trunk muscle functions in patients with spinal cord injury when walking with un-powered exoskeletons.

User Evaluation of a Dynamic Arm Orthosis for People With Neuromuscular Disorders.

This paper presents the results of an online survey conducted with users of a functional upper extremity orthosis called the Wilmington Robotic EXoskeleton (WREX). The WREX is a passive anti-gravity arm orthosis that allows people with neuromuscular disabilities to move their arms in three dimensions. The paper also describes the design of a novel lightweight 3-D printed WREX used for ambulatory children. Three different versions of the WREX are now offered to patients. Two can be mounted on a wheelchair and one to a body jacket for ambulatory patients. An online user survey with 55 patients was conducted to determine the benefits of the various WREXs. The survey asked ten questions related to upper extremity function with and without the WREX as well as subjective impressions of the device. Results show a statistically significant improvement in arm function for everyday tasks with the WREX.

Lower-limb exoskeletons for individuals with chronic spinal cord injury: findings from a feasibility study.

OBJECTIVE: To assess the feasibility of conducting a well-powered trial evaluating the neurological and functional effects of using an exoskeleton in individuals with chronic spinal cord injury. DESIGN: A longitudinal, prospective, self-controlled feasibility study. SETTING: Specialist Spinal Cord Injuries Centre, UK; 8 months during 2013-2014. SUBJECTS: Individuals with chronic motor complete or incomplete spinal cord injury. INTERVENTIONS: Enrolled subjects were assigned to 20 exoskeleton (ReWalk™, Argo Medical Technologies Ltd, Yokneam Ilit, Israel) training sessions over a 10-week training period. MAIN MEASURES: Feasibility measures, clinical and mobility outcome measures and measures appraising subjects' disability and attitude towards assistive technology were assessed before, during and after the study. Descriptive statistics were applied. RESULTS: Out of 60 candidates, ten (17%) were enrolled and five (8%) completed the training programme. Primary reasons for not enrolling were ineligibility (n = 24, 40%) and limited interest to engage in a 10-week training programme (n = 16, 27%). Five out of ten enrolled subjects experienced grade I/II skin aberrations. While walking speeds were higher and walking distances were longer in all exoskeleton users when compared with non-use, the exoskeleton did generally not meet subjects' high expectations in terms of perceived benefits. CONCLUSIONS: The conduct of a controlled trial evaluating the benefits of using exoskeletons that require a lengthy user-commitment to training of individuals with chronic motor complete or incomplete spinal cord injury comes with considerable feasibility challenges. Vigilance is required for preventing and detecting medical complications in spinal cord injury exoskeleton users.

Hybrid EEG/EOG-based brain/neural hand exoskeleton restores fully independent daily living activities after quadriplegia.

Direct brain control of advanced robotic systems promises substantial improvements in health care, for example, to restore intuitive control of hand movements required for activities of daily living in quadriplegics, like holding a cup and drinking, eating with cutlery, or manipulating different objects. However, such integrated, brain- or neural-controlled robotic systems have yet to enter broader clinical use or daily life environments. We demonstrate full restoration of independent daily living activities, such as eating and drinking, in an everyday life scenario across six paraplegic individuals (five males, 30 ± 14 years) who used a noninvasive, hybrid brain/neural hand exoskeleton (B/NHE) to open and close their paralyzed hand. The results broadly suggest that brain/neural-assistive technology can restore autonomy and independence in quadriplegic individuals' everyday life.