Functional electrical stimulation-based cycling assisted by flywheel and electrical clutch mechanism: A feasibility simulation study

• A flywheel and electrical clutch assist mechanism is used in FES-cycling exercise.
• Fuzzy logic is used to control stimulation intensity on quadriceps in FES-cycling.
• The new mechanism suppresses speed fluctuation and reduces the cadence error.
• The new assist mechanism promotes prolonged FES-cycling and extended work rate.
• The fatigue monitor shows 14%–17% delay in muscle fatigue using the new mechanism.

A new assist mechanism, represented by a flywheel and an electrical clutch, is developed and evaluated, in simulation studies, to assist paralysed legs during functional electrical stimulation (FES)-based cycling exercise in a closed-loop control configuration. The flywheel is engaged and disengaged, by the clutch, to assist or retard the cycling when necessary. The flywheel engages with the crank to absorb the surplus energy, produced by stimulating the leg, store it as kinetic energy and slow down the movement. Also, it engages again to use the same stored energy to assist the leg and speed up the cycling. A comparative assessment of FES-cycling, using fuzzy logic control, is carried out with and without the new assist mechanism. Clinically recorded data is used to derive a force-drop indicator for assessment purposes. Although the stimulation intensity is slightly increased, the indicator showed 14%–17% muscle fatigue delay with the new mechanism as compared with cycling without assistance. This mechanism is promoting prolonged FES-cycling and increased work rate for paraplegics by delaying the occurrence of muscle fatigue.