Efficacy of coordinating shoulder and elbow motion in a myoelectric transhumeral prosthesis in reaching tasks

Abstract

This paper presents a control approach for myoelectric transhumeral prostheses that coordinates the movement of the elbow joint with the movement of the (intact) shoulder. The method combines input from a pair of surface electromyograms (EMG) inputs with information from an inertia measurement unit (IMU) to provide coordinated control of the joints, as described in the paper. In order to assess the efficacy of the control method, experiments were conducted on six healthy subjects using a virtual environment, comparing their ability to perform various pick-and-place tasks, specifically requiring that they pick a virtual ball from a given location and place it in a virtual box, which changed location randomly. The time required to complete a series of pick-and-place tasks using the coordinated control approach was compared to the time required to complete the tasks using a conventional sequential control approach. For these experiments, the average task completion time across all sessions and subjects was 12.8 s using the conventional sequential control approach, versus 8.7 s using the coordinated control approach (i.e., subjects performed the task 32% faster with the proposed approach), indicating that the proposed approach provides improved performance relative to the conventional approach.