“…Therefore, applying a pre-specified stimulation pattern in openloop FES systems cannot obtain the proper performance. To solve the problem, researches have proposed many control strategies of single-joint movement (eg, ankle, or knee joints) (3)(4)(5)(6)(7)(8)(9) and multi-joint motion (eg, cycling, standing, or walking) (10)(11)(12)(13). The proposed methods included adaptive feedback control (14), fuzzy control (5,15), PID control (4,16), neural control (17), sliding mode control (5,6,18), gain scheduling (8), nonlinear model predictive control (9,19,20), and so on.…”