Control of a wrist joint motion simulator: a phantom study
File(s)
Published version
Accepted version
Author(s)
Shah, D
Kedgley, AE
Type
Journal Article
Abstract
The presence of muscle redundancy and co-activation of agonist-antagonist pairs in vivo makes the optimization of the load distribution between muscles in physiologic joint simulators vital. This optimization is usually achieved by employing different control strategies based on position and/or force feedback. A muscle activated physiologic wrist simulator was developed to test and iteratively refine such control strategies on a functional replica of a human arm. Motions of the wrist were recreated by applying tensile loads using electromechanical actuators. Load cells were used to monitor the force applied by each muscle and an optical motion capture system was used to track joint angles of the wrist in real-time. Four control strategies were evaluated based on their kinematic error, repeatability and ability to vary co-contraction. With kinematic errors of less than 1.5°, the ability to vary co-contraction, and without the need for predefined antagonistic forces or muscle force ratios, novel control strategies – hybrid control and cascade control – were preferred over standard control strategies – position control and force control. Muscle forces obtained from hybrid and cascade control corresponded well with in vivo EMG data and muscle force data from other wrist simulators in the literature. The decoupling of the wrist axes combined with the robustness of the control strategies resulted in complex motions, like dart thrower’s motion and circumduction, being accurate and repeatable. Thus, two novel strategies with repeatable kinematics and physiologically relevant muscle forces are introduced for the control of joint simulators.
Date Issued
2016-07-12
Date Acceptance
2016-07-06
Citation
Journal of Biomechanics, 2016, 49 (13), pp.3061-3068
ISSN
1873-2380
Publisher
Elsevier
Start Page
3061
End Page
3068
Journal / Book Title
Journal of Biomechanics
Volume
49
Issue
13
Copyright Statement
Under a Creative Commons Attribution 4.0 International Licence (CC BY 4.0)
License URL
Sponsor
Arthritis Research UK
The Royal Society
Grant Number
20556
RG130400
Subjects
wrist
simulator
kinematics
control strategy
muscle forces
Publication Status
Published