| Summary: | 碩士 === 國立成功大學 === 醫學工程學系 === 81 === The aim of this research is to develop an FES-cycling control
which can maintain at a desired cycling speed. For controlling
the movement of a paralyzed limb, proper design of the
stimulation pattern is required. In the FES-cycling system, the
stimulation current generated by a 4-channel stimulator is
controlled by a PC-486 computer. The quadriceps and hamstrings
of both legs are stimulated to generate cycling movement. As a
reference for the generation of stimulation patterns, a linear
envelope (LE) form of EMG is derived, by processing the EMG of
quadriceps and hamstrings generated from a normal subject
during cycling. The EMG LE stimulation patterns is then
obtained by mapping EMG LE through the inverse isometric
recruitment curve. EMG LE pattern can provide a systematic
design and lead to smooth cycling movement when compared with
the on-off and the ramp-like patterns used in previous work.
Based on the EMG LE stimulation pattern, a closed-loop FES
control system is developed. As a structure for FES-cycling
control scheme, a proportional plus integral plus differential
(PID) controller of cyclic knee angle by stimulating only the
quadriceps is studied. Parameters of the PID controller are
tuned to control the maximum knee angle in each cycle to a
preset angle. The model and parameters of knee angle controller
is adopted for FES-cycling control system. To simplify the
cycling control system, stimulation patterns are fixed and only
the single gain of the stimulation patterns is adjusted. The
closed-loop FES cycling control system thus becomes a signal
input and signal output system. This control system developed
enables the subject to maintain the cycling speed and overcome
the muscle fatigue factors.
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