Preliminary tests of a prototype FES control system for cycling wheelchair rehabilitation

The cycling wheelchair "Profhand" developed by our research group in Japan has been found to be useful in rehabilitation of motor function of lower limbs. It is also expected for rehabilitation of paraplegic subjects to propel the cycling wheelchair by lower limbs controlled by functional electrical stimulation (FES). In this paper, a prototype FES control system for the cycling wheelchair was developed using wireless surface stimulators and wireless inertial sensors and tested with healthy subjects. The stimulation pattern that stimulated the quadriceps femoris and the gluteus maximus at the same time was shown to be effective to propel the Profhand. From the analysis of steady state cycling, it was shown that the cycling speed was smaller and the variation of the speed was larger in FES cycling than those of voluntary cycling. Measured angular velocity of the crank suggested that stimulation timing have to be changed considering delay in muscle response to electrical stimulation and cycling speed in order to improve FES cycling. It was also suggested that angle of the pedal have to be adjusted by controlling ankle joint angle with FES in order to apply force appropriately.