Six weeks Use of a Wearable Soft-robotic Glove During ADL:Preliminary Results of Ongoing Clinical Study

In this ongoing study, an assistive wearable soft-robotic glove, named Carbonhand, is tested at home for 6 weeks by subjects with decreased handgrip strength to receive a first insight in the therapeutic effect of using this assistive grip-supporting glove during ADLs. Preliminary results of the first 13 participants showed that participants appreciated use of the glove to assist them with daily life activities. Even more, grip strength without glove improved and functional performance showed increases as well. These preliminary findings hold promise for observing a clinical effect of using the soft-robotic glove as assistance in ADLs upon completion of data collection

Therapy effect on hand function after home use of a wearable assistive soft-robotic glove supporting grip strength

Background Soft-robotic gloves with an assist-as-needed control have the ability to assist daily activities where needed, while stimulating active and highly functional movements within the user’s possibilities. Employment of hand activities with glove support might act as training for unsupported hand function. Objective To evaluate the therapeutic effect of a grip-supporting soft-robotic glove as an assistive device at home during daily activities. Methods This multicentre intervention trial consisted of 3 pre-assessments (averaged if steady state = PRE), one post-assessment (POST), and one follow-up assessment (FU). Participants with chronic hand function limitations were included. Participants used the Carbonhand glove during six weeks in their home environment on their most affected hand. They were free to choose which activities to use the glove with and for how long. The primary outcome measure was grip strength, secondary outcome measures were pinch strength, hand function and glove use time. Results 63 patients with limitations in hand function resulting from various disorders were included. Significant improvements (difference PRE-POST) were found for grip strength (+1.9 kg, CI 0.8 to 3.1; p = 0.002) and hand function, as measured by Jebson-Taylor Hand Function Test (-7.7 s, CI -13.4 to -1.9; p = 0.002) and Action Research Arm Test (+1.0 point, IQR 2.0; p≤0.001). Improvements persisted at FU. Pinch strength improved slightly in all fingers over six-week glove use, however these differences didn’t achieve significance. Participants used the soft-robotic glove for a total average of 33.0 hours (SD 35.3), equivalent to 330 min/week (SD 354) or 47 min/day (SD 51). No serious adverse events occurred. Conclusion The present findings showed that six weeks use of a grip-supporting soft-robotic glove as an assistive device at home resulted in a therapeutic effect on unsupported grip strength and hand function. The glove use time also showed that this wearable, lightweight glove was able to assist participants with the performance of daily tasks for prolonged periods

Human force reproduction error depends upon force level

For optimal haptic tele-manipulation system design, it is important to understand the accuracy and limitations of human force perception. Previous research demonstrated that humans generate higher forces when asked to reproduce an externally applied force; these studies proposed that the nervous system attenuates feedback from self-generated forces. The goal of this study was to determine how accurately subjects reproduce self-generated forces with the same hand over a broad range of force levels. Subjects (n=10, all right handed) had to generate an onscreen target force with visual support and subsequently reproduce the same force without visual support with their right hand against a static handle equipped with a force sensor. Six force levels (10 to 160N) were each presented randomly for eight repetitions. Subjects generated too high forces for lower force levels (≤40N) and too low forces for higher force levels (≥ 130N). Our results support force-dependent sensory integration and demonstrate that attenuated feedback of self-generated forces is not the sole factor in force reproduction errors

Delays in admittance-controlled haptic devices make simulated masses feel heavier

\u3cp\u3eIn an admittance-controlled haptic device, input forces are used to calculate the movement of the device. Although developers try to minimize delays, there will always be delays between the applied force and the corresponding movement in such systems, which might affect what the user of the device perceives. In this experiment we tested whether these delays in a haptic human-robot interaction influence the perception of mass. In the experiment an admittance-controlled manipulator was used to simulate various masses. In a staircase design subjects had to decide which of two virtual masses was heavier after gently pushing them leftward with the right hand in mid-air (no friction, no gravity). The manipulator responded as quickly as possible or with an additional delay (25 or 50 ms) to the forces exerted by the subject on the handle of the haptic device. The perceived mass was10% larger for a delay of 25 ms and20% larger for a delay of 50 ms. Based on these results, we estimated that the delays that are present in nowadays admittance-controlled haptic devices (up to 20ms) will give an increase in perceived mass which is smaller than the Weber fraction for mass (10% for inertial mass). Additional analyses showed that the subjects' decision on mass when the perceptual differences were small did not correlate with intuitive variables such as force, velocity or a combination of these, nor with any other measured variable, suggesting that subjects did not have a consistent strategy during guessing or used other sources of information, for example the efference copy of their pushes.\u3c/p\u3

Results of the component analysis.

<p>For each measure the percentage of trials in which subjects choose the largest (on this metric) as being the heavier one is shown for the first, second and last part of the trials. Error bars indicate the SE’s. In the first part many measures correlate, but when in the third part the perceptual differences between the test and reference mass are small, there are no longer any significant correlations with the subjects’ decisions.</p

Schematic representation (not to scale) of the task and experimental procedure.

<p>The haptic device started ~30 cm in front of the subject’s torso, and 10 cm to the right of the body’s midline. Subjects were blindfolded and were wearing headphones. At a beep the subject pushed the handle gently to the left. After the push the haptic device moved back to the start position, at a second beep the subject pushed again and judged which of the two felt the heaviest.</p

Staircases for an example subject, showing how our analysis method deals with data that is not optimal.

<p>For each delay (0ms; blue trace, 25ms; green trace, 50ms; red trace) the data converge towards the perceived mass (dashed lines), calculated based on the last 6 reversals of the two staircases (open squares are the reversals from the staircases from above and filled squares from below). The data of the 50 ms delay (red) converged later than the others and the two staircases of the 50 ms delay reached their stabile value at different moments (trial numbers). For 0ms additional delay the perceived mass is 6.2kg, which is close to the reference mass (thin grey solid line). For 25ms additional delay and 50ms, the perceived masses increase to 6.7kg and 7.5kg respectively. The blue and red curves are shifted slightly rightwards for clarity. The light grey background colours indicate the subdivision into three parts used in the component analysis (see text for details).</p

Results.

<p>The grey lines show the perceived mass based on the last six reversals of the staircases for each subject. Most subjects show an increasing trend. The coloured squares show the mean perceived mass for the delays. Error bars show standard errors of the mean.</p

Development of a single device to quantify motor impairments of the elbow: proof of concept

Background: For patients with post-stroke upper limb impairments, the currently available clinical measurement instruments are inadequate for reliable quantification of multiple impairments, such as muscle weakness, abnormal synergy, changes in elastic joint properties and spasticity. Robotic devices to date have successfully achieved precise and accurate quantification but are often limited to the measurement of one or two impairments. Our primary aim is to develop a robotic device that can effectively quantify four main motor impairments of the elbow. Methods: The robotic device, Shoulder Elbow Perturbator, is a one-degree-of-freedom device that can simultaneously manipulate the elbow joint and support the (partial) weight of the human arm. Upper limb impairments of the elbow were quantified based on four experiments on the paretic arm in ten stroke patients (mean age 65 ± 10 yrs, 9 males, post-stroke) and the non-dominant arm in 20 healthy controls (mean age 65 ± 14 yrs, 6 males). The maximum strength of elbow flexor and elbow extensor muscles was measured isometrically at 90-degree elbow flexion. The maximal active extension angle of the elbow was measured under different arm weight support levels to assess abnormal synergy. Torque resistance was analyzed during a slow (6°/s) passive elbow rotation, where the elbow moved from the maximal flexion to maximal extension angle and back, to assess elastic joint properties. The torque profile was evaluated during fast (100°/s) passive extension rotation of the elbow to estimate spasticity. Results: The ten chronic stroke patients successfully completed the measurement protocol. The results showed impairment values outside the 10th and 90th percentile reference intervals of healthy controls. Individual patient profiles were determined and illustrated in a radar figure, to support clinicians in developing targeted treatment plans. Conclusion: The Shoulder Elbow Perturbator can effectively quantify the four most important impairments of the elbow in stroke patients and distinguish impairment scores of patients from healthy controls. These results are promising for objective and complete quantification of motor impairments of the elbow and monitoring patient prognosis. Our newly developed Shoulder Elbow Perturbator can therefore in the future be employed to evaluate treatment effects by comparing pre- and post-treatment assessments

Reliability and Validity of a New Diagnostic Device for Quantifying Hemiparetic Arm Impairments: An Exploratory Study

Objective: To assess test-retest reliability and validity of a new diagnostic device, the Shoulder Elbow Perturbator, to quantify muscle weakness, abnormal synergy, (muscle activity-related) spasticity, and changes in viscoelastic joint properties of the elbow.Subjects: Stroke patients, adults with cerebral palsy and healthy controls.Methods: Test-retest reliability was evaluated using intra-class correlations (ICC) and assessment of measurement error. The device's validity was evaluated by demonstrating differences between patients and healthy controls, and correlations of spasticity and abnormal synergy outcomes using the clinical Modified Tardieu Scale, the Fugl-Meyer Assessment, and the Test of Arm Selective Control.Results: Reliability was excellent, with an ICC > 0.75 for synergy and ICCs > 0.90 for all other impairments, with relatively small measurement errors. Validity was confirmed by group differences between patients and healthy controls for muscle weakness, spasticity, and viscoelastic joint properties, but not for abnormal synergy. Correlation analysis with clinical scales confirmed validity for spasticity, while, for synergy, correlations were found in the patients with stroke, but not those with cerebral palsy.Conclusion: This new diagnostic device is a reliable and valid instrument to assess multiple upper limb impairments in patients with neurological conditions, supporting its use in clinical practice. Further studies are needed to confirm these findings