Control strategies for nonlinear dynamics of muscle relaxant anaesthesia

Using modern nonlinear identification techniques, dose-response dynamics for two muscle relaxant trials have been obtained. A so-called NARMAX model has been found for Vecuronium applied to a dog, and Atracurium given to a human. With the relaxant dynamics structure thus obtained, the work proceeded to the control phase. Simple three-term PID controllers were first designed with their parameters being optimised, off-line, using the Simplex method. The non-adaptive nature of this class of controllers makes their robustness open to question when the system parameters for which they have been optimised change. Hence, adaptive controllers in the form of linear and nonlinear generalised minimum variance self-tuners, generalised predictive control and nonlinear k-step ahead predictive controllers are also considered. All of these latter control approaches are shown to be satisfactory, in terms of transient and steady-state performance.