Design of closed-loop fuzzy FES controller and tests in controlling knee extension movements

Fuzzy controller can be useful to realize a practical closed-loop FES controller, because it is possible to make it easy to design FES controller and to determine its parameter values, especially for controlling multi-joint movements by stimulating many muscles including antagonistic muscle pairs. This study focused on using fuzzy controller for the closed-loop control of cycling speed during FES cycling with pedaling wheelchair. However, a designed fuzzy controller has to be tested experimentally in control performance. In this paper, a closed-loop fuzzy FES controller was designed and tested in knee extension movements comparing to a PID controller with healthy subjects before applying to FES cycling. The developed fuzzy controller showed good control performance as a whole in comparing to PID controller and its parameter values were determined through simple control tests of the target movement.