FNS control system tuning and clinical ratings of performance

A feedback controller of coronal plane hip angle was implemented in paraplegic subjects using functional neuromuscular stimulation (FNS). In an evaluation based on standard temporal response properties, the feedback-controlled system exhibited substantial improvements when compared to an open-loop system. An evaluation based on subjective clinical observations of the experimental trials indicates that standard control system design criteria may not correspond to desired performance characteristics. Consideration of the clinical ratings and identified system model parameters suggests other design criteria which may be more relevant