Pilot Study for Myoelectric Control of a Supernumerary Robot During a Coordination Task

Abstract

Robots are used in a wide variety of applications to augment the capability of humans. A relatively new category of assistive robots, supernumerary robots (SRs), create an additional, kinematically independent limb or appendage that may serve various functions. SR research has centered on device development and proof-of-concept but has generally not focused on the human interface and human-robot performance. In this pilot study, four subjects completed 80 cursor-to-target trials of a three-handed coordination task with a collaborative robot. The subjects used their two natural hands to control a cursor on a screen in 2-DOFs (degrees of freedom) and used a leg muscle signal to control the robotic hand. The robotic hand controlled the cursor in the third DOF. We calculated two metrics to assess coordination, the coordination score and the DOF activation. Subjects improved in the coordination score and DOF activation throughout the study duration. The subjects increased the percentage of trial time with 3-DOFs active and correspondingly decreased 1-DOF activation. The results indicated that subjects learned how to improve their coordination, while successfully completing trials and decreasing their trial completion time. The subjects tended to coordinate most of the time with their hands (41%) followed by all three limbs (19%). Future studies should focus on increasing the proportion of 3-DOF coordination for improved human-robot performance.