Quasi-Static Control of Whole-Arm Motions with FES

This paper introduces a quasi-static method for controlling reaching movements of a paralyzed human arm using FES. A subject-specific model was estimated from experimental data collected from a single subject with a high cervical spinal cord injury who uses a functional electrical stimulation neuroprosthesis. We tested a controller based on this model that maps desired shoulder and elbow joint positions to muscle stimulation commands. The controller tracked the desired lateral direction of hand movements well but did not track forward/backward or vertical movements well. The lateral position of the hand was not greatly affected by the direction of movement given identical stimulation commands, which supports the hypothesis that velocity information is not required for tracking slow hand movements.