Improvements on VSS-type self-tuning control for a tracking controller

This paper points out that the VSS-type self-tuning controller of Furuta [1] can be improved by modifications of the sector with separate gains and the equivalent control algorithm. The controlled system is stable in the outside of the sector and ultimately bounded in the inside of the sector. The proposed VSS-type self-tuning controller prevents the fluctuation of the estimated parameters that can occur during the parameter adaptation. This controller, having reduced the switching sector, is actually applicable to the tracking control of discrete systems in the presence of parameter uncertainties.