Control for FES hand grasp systems using accelerometers and gyroscopes

A new command controller was designed to enhance the performance of Functional Electrical Stimulation (FES) hand grasp system. This controller used miniature gyroscopes and accelerometers to detect the residual voluntary movements of shoulder and elbow joint of persons with cervical spinal cord injury at C4 to C6 level to generate meaningful command signals for controlling different stimulation patterns. Five normal subjects and three cervical spinal cord injured (SCI) subjects were recruited to evaluate this controller. Sensors were placed on the shoulder, upper arm, wrist and hand. The success rate of using these sensors with the new developed control algorithm ranged from 85% to 100% on normal subjects and from 82% to 97% on SCI subjects. In terms of sensor placement, the gyroscope was better as the control source than the accelerometer for the wrist and hand positions, but the accelerometer had better performance on the shoulder position.