Control of a time-delayed 5 degrees of freedom arm model for use in upper extremity functional electrical stimulation.
The goal of this work is to design a controller for a functional electrical stimulation (FES) neuroprosthesis aimed at restoring shoulder and elbow function in individuals who have suffered a high-level cervical (C3-C4) spinal cord injury (SCI). The controller is a mathematical algorithm that coordinates the electrical stimulations applied to the paralyzed muscles such that the arm closely tracks a given desired trajectory. An issue that so far has received little attention is that of time-delays. These delays arise from two sources: (1) the muscle excitation-activation dynamics (10-30 ms) and (2) the sampling of the electrical stimulation (80 ms at the typical 12 Hz stimulation frequency). Using a 5 degrees of freedom (5 DOF) arm model we designed and evaluated a novel controller capable of maintaining stable and accurate tracking performance in the presence of time-delays. For a desired trajectory consisting of 10 randomized reaches, the controller achieved excellent tracking performance as measured by the root-mean-square error (RMSE) between the desired and simulated joint angles (RMSE= [1.48°; 0.81°; 2.14°; 3.11°; 2.29°]).
Biomedical Engineering Department, Case Western Reserve University, OH 44120, USA. pxc75@case.edu
P
P
Cooman
R F
RF
Kirsch
D000465:Algorithms; D001132:Arm / Q000503:physiopathology*; D004558:Electric Stimulation; D006801:Humans; D008954:Models, Biological; D009068:Movement; D058117:Neural Prostheses; D010291:Paresis / Q000503:physiopathology*; D011474:Prosthesis Design; D013119:Spinal Cord Injuries / Q000503:physiopathology*