Simultaneous and Proportional Estimation of Multiple DOFs for Myoelectric Prostheses: A Comparison between Force and Position Control Paradigms

Abstract

This paper studies the problem of simultaneous and proportional myoelectric control of multiple DOFs for unilateral transradial amputees. Two control strategies namely force and position estimations were investigated. In the first, a force experiment, the subject performed isometric contractions while the force applied by the limb was measured. In the second, a position experiment, limb free movements were permitted during which limb joint angle was recorded. Artificial neural networks (ANN) were trained to estimate force/position from EMG of the contralateral limb during mirrored bilateral contractions. This research used contractions with combined activations of three DOFs including wrist: flexion/extension, radial/ulnar deviation and forearm supination/pronation. In the case of the contralateral limb, force estimation (R2 =0.79±0.03) demonstrated significantly higher performance with respect to position estimation (R2 =0.73±0.04).