An experimental test of fuzzy controller based on cycle-to-cycle control for FES-induced gait: Knee joint control with neurologically intact subjects

Functional Electrical Stimulation (FES) can be effective in assisting or restoring paralyzed motor functions caused by the spinal cord injury or the celebrovascular disease. The purpose of this study was to develop a control method of gait induced by FES. We had proposed a fuzzy control system based on cycle-to-cycle control for controlling hip, knee and ankle joints during the swing phase of FESinduced gait and evaluated it in computer simulation studies. In this report, the fuzzy controller was tested experimentally in controlling maximum knee extension angle stimulating the vastus muscles using surface electrodes with neurologically intact subjects. The fuzzy controller worked properly in regulating stimulation burst duration time and the maximum knee extension angle was controlled well. The experimental results suggested that the fuzzy controller would be practical in clinical applications for the control of FES-induced gait. However, it was also suggested that electrical stimulation with large burst duration time or muscle fatigue caused a change in muscle response. Including automatic controller parameter tuning during a gait control and further experimental tests were necessary for practical applications.