Dynamic simulation of FES-cycling: influence of individual parameters

Abstract

Cycling by means of functional electrical simulation (FES) is an attractive training method for spinal cord injured (SCI) subjects. FES-cycling performance is influenced by a number of parameters like seating position, physiological parameters, conditions of surface stimulation, and pedaling rate. The objective of this paper was the determination of the influence of the most important parameters on optimal muscle stimulation patterns and power output of FES-cycling on a noncircular pedal path. The rider-cycle system was modeled as a planar articulated rigid body linkage on which the muscle forces are applied via joint moments and implemented into a forward dynamic simulation of FES-cycling. For model validation, the generated drive torques that are predicted by the simulation were compared to measurements with an individual paraplegic subject. Then, a sensitivity analysis was carried out to determine the influences of the most important parameters for surface stimulation of gluteus maximus, quadriceps, hamstrings, and peroneus reflex. The results show how optimal stimulation patterns and the expected mean active power output can be estimated based on measured individual parameters and adjusted geometry and stimulation parameters for a particular SCI-subject. This can considerably improve FES-cycling performance and relieve the patients by shortening the time that is necessary for experimental adaptation of the stimulation patterns.

Comparison of stimulation patterns for FES-cycling using measures of oxygen cost and stimulation cost

“…Other groups have attempted to numerically optimize activation angles by maximizing an analytical cost function which captures mechanical output forces [21,22,23,24]. This approach is based upon a dynamic simulation model of lower-limb cycling, and has not thus far been experimentally verified.…”

Can the efficacy of electrically stimulated pedaling using a commercially available ergometer BE improved by minimizing the muscle stress–time integral?

“…To our knowledge, the timing patterns from these studies have not been tested experimentally. The timing patterns for the QUADS, GLUTS, and HAMS from these two studies, as well as several other simulation studies designed to maximize pedaling power, [54][55][56] enveloped those of both StimErg and Stim3. A disadvantage of increased stimulation duration is the associated longer duty cycle.…”

Cadence control of stationary cycling induced by switched functional electrical stimulation control

“…Past FES-cycling control methods have utilized linear controllers [9]- [11], fuzzy logic and sliding mode controllers [12]- [14], or controllers based on experimental data or numerical optimizations [15]- [18]. All of these previous studies lack detailed stability analyses or require exact model knowledge.…”