scholarly journals Human Weight Compensation With a Backdrivable Upper-Limb Exoskeleton: Identification and Control

2022 ◽  
Vol 9 ◽  
Author(s):  
Dorian Verdel ◽  
Simon Bastide ◽  
Nicolas Vignais ◽  
Olivier Bruneau ◽  
Bastien Berret
Keyword(s):  
Upper Limb ◽  
Elbow Flexion ◽  
Population Based ◽  
Model Errors ◽  
Tracking Errors ◽  
Upper Limb Exoskeleton ◽  
Weight Support ◽  
Flexion Extension ◽  
Weight Compensation ◽  
And Control

Active exoskeletons are promising devices for improving rehabilitation procedures in patients and preventing musculoskeletal disorders in workers. In particular, exoskeletons implementing human limb’s weight support are interesting to restore some mobility in patients with muscle weakness and help in occupational load carrying tasks. The present study aims at improving weight support of the upper limb by providing a weight model considering joint misalignments and a control law including feedforward terms learned from a prior population-based analysis. Three experiments, for design and validation purposes, are conducted on a total of 65 participants who performed posture maintenance and elbow flexion/extension movements. The introduction of joint misalignments in the weight support model significantly reduced the model errors, in terms of weight estimation, and enhanced the estimation reliability. The introduced control architecture reduced model tracking errors regardless of the condition. Weight support significantly decreased the activity of antigravity muscles, as expected, but increased the activity of elbow extensors because gravity is usually exploited by humans to accelerate a limb downwards. These findings suggest that an adaptive weight support controller could be envisioned to further minimize human effort in certain applications.

scholarly journals Human Weight Compensation with a Backdrivable Upper-Limb Exoskeleton: Identification and Control

2021 ◽  
Author(s):  
Dorian VERDEL ◽  
Simon Bastide ◽  
Nicolas Vignais ◽  
Olivier Bruneau ◽  
Bastien Berret
Keyword(s):  
Upper Limb ◽  
Elbow Flexion ◽  
Population Based ◽  
Model Errors ◽  
Tracking Errors ◽  
Upper Limb Exoskeleton ◽  
Weight Support ◽  
Flexion Extension ◽  
Weight Compensation ◽  
And Control

Abstract Active exoskeletons are promising devices for improving rehabilitation procedures in patients and preventing musculoskeletal disorders in workers. In particular, exoskeletons implementing human limb’s weight support are interesting to restore some mobility in patients with muscle weakness and help in occupational load carrying tasks. The present study aims at improving weight support of the upper limb by providing a weight model considering joint misalignments and a control law including feedforward terms learned from a prior population-based analysis. Three experiments, for design and validation purposes, are conducted on a total of 65 participants who performed posture maintenance and elbow flexion/extension movements. The introduction of joint misalignments in the weight support model significantly reduced the model errors, in terms of weight estimation, and enhanced the estimation reliability. The introduced control architecture reduced model tracking errors regardless of the condition. Weight support significantly decreased the activity of antigravity muscles, as expected, but increased the activity of elbow extensors because gravity is usually exploited by humans to accelerate a limb downwards. These findings suggest that an adaptive weight support controller could be envisioned to further minimize human effort in certain applications.

scholarly journals Measures of Interjoint Coordination Post-stroke Across Different Upper Limb Movement Tasks

2021 ◽  
Vol 8 ◽  
Author(s):  
Anne Schwarz ◽  
Janne M. Veerbeek ◽  
Jeremia P. O. Held ◽  
Jaap H. Buurke ◽  
Andreas R. Luft
Keyword(s):  
Upper Limb ◽  
Elbow Flexion ◽  
Shoulder Abduction ◽  
Kinematic Parameters ◽  
Limb Function ◽  
Interjoint Coordination ◽  
Upper Limb Function ◽  
Shoulder Flexion ◽  
Flexion Extension ◽  
Median Slope

Background: Deficits in interjoint coordination, such as the inability to move out of synergy, are frequent symptoms in stroke subjects with upper limb impairments that hinder them from regaining normal motor function. Kinematic measurements allow a fine-grained assessment of movement pathologies, thereby complementing clinical scales, like the Fugl–Meyer Motor Assessment of the Upper Extremity (FMMA-UE). The study goal was to investigate the effects of the performed task, the tested arm, the dominant affected hand, upper limb function, and age on spatiotemporal parameters of the elbow, shoulder, and trunk. The construct validity of the metrics was examined by relating them with each other, the FMMA-UE, and its arm section.Methods: This is a cross-sectional observational study including chronic stroke patients with mild to moderate upper limb motor impairment. Kinematic measurements were taken using a wearable sensor suit while performing four movements with both upper limbs: (1) isolated shoulder flexion, (2) pointing, (3) reach-to-grasp a glass, and (4) key insertion. The kinematic parameters included the joint ranges of shoulder abduction/adduction, shoulder flexion/extension, and elbow flexion/extension; trunk displacement; shoulder–elbow correlation coefficient; median slope; and curve efficiency. The effects of the task and tested arm on the metrics were investigated using a mixed-model analysis. The validity of metrics compared to clinically measured interjoint coordination (FMMA-UE) was done by correlation analysis.Results: Twenty-six subjects were included in the analysis. The movement task and tested arm showed significant effects (p < 0.05) on all kinematic parameters. Hand dominance resulted in significant effects on shoulder flexion/extension and curve efficiency. The level of upper limb function showed influences on curve efficiency and the factor age on median slope. Relations with the FMMA-UE revealed the strongest and significant correlation for curve efficiency (r = 0.75), followed by shoulder flexion/extension (r = 0.68), elbow flexion/extension (r = 0.53), and shoulder abduction/adduction (r = 0.49). Curve efficiency additionally correlated significantly with the arm subsection, focusing on synergistic control (r = 0.59).Conclusion: The kinematic parameters of the upper limb after stroke were influenced largely by the task. These results underpin the necessity to assess different relevant functional movements close to real-world conditions rather than relying solely on clinical measures.Study Registration: clinicaltrials.gov, identifier NCT03135093 and BASEC-ID 2016-02075.

scholarly journals Characterization of stroke-related upper limb motor impairments across various upper limb activities by use of kinematic core set measures

2022 ◽  
Vol 19 (1) ◽  
Author(s):  
Anne Schwarz ◽  
Miguel M. C. Bhagubai ◽  
Saskia H. G. Nies ◽  
Jeremia P. O. Held ◽  
Peter H. Veltink ◽  
...  
Keyword(s):  
Upper Limb ◽  
Daily Living ◽  
Healthy Subjects ◽  
Peak Velocity ◽  
Movement Time ◽  
Elbow Flexion ◽  
Wrist Flexion ◽  
Shoulder Flexion ◽  
Flexion Extension

Abstract Background Upper limb kinematic assessments provide quantifiable information on qualitative movement behavior and limitations after stroke. A comprehensive characterization of spatiotemporal kinematics of stroke subjects during upper limb daily living activities is lacking. Herein, kinematic expressions were investigated with respect to different movement types and impairment levels for the entire task as well as for motion subphases. Method Chronic stroke subjects with upper limb movement impairments and healthy subjects performed a set of daily living activities including gesture and grasp movements. Kinematic measures of trunk displacement, shoulder flexion/extension, shoulder abduction/adduction, elbow flexion/extension, forearm pronation/supination, wrist flexion/extension, movement time, hand peak velocity, number of velocity peaks (NVP), and spectral arc length (SPARC) were extracted for the whole movement as well as the subphases of reaching distally and proximally. The effects of the factors gesture versus grasp movements, and the impairment level on the kinematics of the whole task were tested. Similarities considering the metrics expressions and relations were investigated for the subphases of reaching proximally and distally between tasks and subgroups. Results Data of 26 stroke and 5 healthy subjects were included. Gesture and grasp movements were differently expressed across subjects. Gestures were performed with larger shoulder motions besides higher peak velocity. Grasp movements were expressed by larger trunk, forearm, and wrist motions. Trunk displacement, movement time, and NVP increased and shoulder flexion/extension decreased significantly with increased impairment level. Across tasks, phases of reaching distally were comparable in terms of trunk displacement, shoulder motions and peak velocity, while reaching proximally showed comparable expressions in trunk motions. Consistent metric relations during reaching distally were found between shoulder flexion/extension, elbow flexion/extension, peak velocity, and between movement time, NVP, and SPARC. Reaching proximally revealed reproducible correlations between forearm pronation/supination and wrist flexion/extension, movement time and NVP. Conclusion Spatiotemporal differences between gestures versus grasp movements and between different impairment levels were confirmed. The consistencies of metric expressions during movement subphases across tasks can be useful for linking kinematic assessment standards and daily living measures in future research and performing task and study comparisons. Trial registration: ClinicalTrials.gov Identifier NCT03135093. Registered 26 April 2017, https://clinicaltrials.gov/ct2/show/NCT03135093.

scholarly journals Measuring Upper Limb Kinematics of Forehand and Backhand Topspin Drives with IMU Sensors in Wheelchair and Able-Bodied Table Tennis Players

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8303
Author(s):  
Jia-Wen Yam ◽  
Jing-Wen Pan ◽  
Pui-Wah Kong
Keyword(s):  
Upper Limb ◽  
Wrist Joint ◽  
Elbow Flexion ◽  
Measurement Unit ◽  
Shoulder Abduction ◽  
Table Tennis ◽  
Tennis Players ◽  
Movement Strategies ◽  
Flexion Extension ◽  
Limb Kinematics

To better understand the biomechanics of para-table tennis players, this study compared the shoulder, elbow, and wrist joint kinematics among able-bodied (AB) and wheelchair players in different classifications. Nineteen participants (AB, n = 9; classification 1 (C1), n = 3; C2, n = 3; C3, n = 4) executed 10 forehand and backhand topspin drives. Shoulder abduction/adduction, elbow flexion/extension, wrist extension/flexion, respective range of motion (ROM), and joint patterns were obtained using inertial measurement unit (IMU) sensors. The results showed clear differences in upper limb kinematics between the able-bodied and wheelchair players, especially in the elbow and wrist. For the para-players, noticeable variations in techniques were also observed among the different disability classes. In conclusion, wheelchair players likely adopted distinct movement strategies compared to AB to compensate for their physical impairments and functional limitations. Hence, traditional table tennis programs targeting skills and techniques for able-bodied players are unsuitable for para-players. Future work can investigate how best to customize training programs and to optimize movement strategies for para-players with varied types and degrees of impairment.

scholarly journals Soft Elbow Exoskeleton for Upper Limb Assistance Incorporating Dual Motor-Tendon Actuator

Electronics ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1184 ◽  
Author(s):  
Rifky Ismail ◽  
Mochammad Ariyanto ◽  
Inri A. Perkasa ◽  
Rizal Adirianto ◽  
Farika T. Putri ◽  
...  
Keyword(s):  
Steady State ◽  
Upper Limb ◽  
Elbow Flexion ◽  
Pi Control ◽  
Test Results ◽  
Wrist Motion ◽  
Dc Motors ◽  
Flexion Extension ◽  
Actuator System

Loss of muscle functions, such as the elbow, can affect the quality of life of a person. This research is aimed at developing an affordable two DOF soft elbow exoskeleton incorporating a dual motor-tendon actuator. The soft elbow exoskeleton can be used to assist two DOF motions of the upper limb, especially elbow and wrist movements. The exoskeleton is developed using fabric for the convenience purpose of the user. The dual motor-tendon actuator subsystem employs two DC motors coupled with lead-to-screw converting motion from angular into linear motion. The output is connected to the upper arm hook on the soft exoskeleton elbow. With this mechanism, the proposed actuator system is able to assist two DOF movements for flexion/extension and pronation/supination motion. Proportional-Integral (PI) control is implemented for controlling the motion. The optimized value of Kp and Ki are 200 and 20, respectively. Based on the test results, there is a slight steady-state error between the first and the second DC motor. When the exoskeleton is worn by a user, it gives more steady-state errors because of the load from the arm weight. The test results demonstrate that the proposed soft exoskeleton elbow can be worn easily and comfortably by a user to assist two DOF for elbow and wrist motion. The resulted range of motion (ROM) for elbow flexion–extension can be varied from 90° to 157°, whereas the maximum of ROM that can be achieved for pronation and supination movements are 19° and 18°, respectively.

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