Author/Editor		Ponikvar, Matija; Munih, M
Title		Self-tuning regulation of muscle generated moment induced by electrical stimulation
Type		članek
Source		In: Mayr W, Bijak M, Jancik C, editors. Proceedings of the 7th Vienna international workshop on functional electrical stimulation; 2001 Sep 12-15: Vienna. Vienna: Department of biomedical engineering and physics University of Vienna,
Publication year		2001
Volume		str. 156-9
Language		eng
Abstract		This paper presents the de velopment, implementation, and experimental evaluation of adaptive feedback system for control of the muscle generated moment. The control system, which utilizes self-tuning regulator (STR) and real-time estimation of local muscle model parameters triggered the stimulator and muscle contractions. Design of such moment controller represents the base leading toward the construction of a position controller. In order to simplify in vivo experiments with FES, we focused only on gastrosoleus muscles under isometric conditions. The stimulated subject stood in mechanical rotating frame (MRF), which prevented rotation of knee, hip and lumbosacral joints. MRF is locked, meaning that also ankle joint is stiff. The moment in the ankle as output of the standing human was measured separately for left and right foot with two force plates. The STR was then used to automatize the muscle model identification and the calculation of controller parameters. The fidelity of muscle models was estimated on-line with least square recursive method which enables the implementation of adaptive control. Adaptive control of electrically stimulated muscle can in real-time embrace the changes caused by time-varying muscle behavior such as fatigue. On-line identification does not require any advance identification procedures and stimulation. The control law was based on the pole placement design that gives desired closed-loop poles. The STR was realized with program Matlab Simulink by using program blocks for identification part, controller, force plates and computer controlled electrical stimulator. The linear controller operation was then tested in three activation regions between stimulation threshold and saturation to exclude nonlinear activation effects. (Abstract truncated at 2000 characters).
Descriptors		PARAPLEGIA ORTHOTIC DEVICES ELECTRIC STIMULATION MOVEMENT SELF-HELP DEVICES