Comparative assessment of two fuzzy logic based control approaches for a flywheel and electrical clutch assist mechanism in FES cycling

Functional electrical stimulation (FES) based cycling exercise for paraplegics, with the aid of a flywheel and electrical clutch mechanism, is introduced. Fuzzy logic controllers are used to control the stimulation intensity on the quadriceps muscle of both legs. The control of the flywheel assist mechanism is achieved using two different fuzzy logic based approaches. The first approach depends on the knee angular velocity of both legs of the trainee while the second approach uses the bicycle´s crank cadence, with the angular velocity of the flywheel, to decide on the engagement/disengagement of the flywheel with the crank. A comparative assessment of the two approaches is carried out and the results are discussed. Results show that the second approach is promoting smoother and longer FES cycling exercise due to reduced stimulation intensity on the muscle, however, it requires a sensitive electrical clutch.