Design of Enhanced Min-Max Control using Feedforward Control

This paper deals with robust control problems of linear systems with matched nonlinear uncertainties. In order to handle the uncertainties, a Lyapunov min-max control approach can usually be adopted. By the way, the min-max control input is required to be switched and provokes chattering phenomena which limit the practical implementation. The magnitude of switching control input which cause chattering is dependent on the size of uncertainties. In this paper, it is shown that the magnitude of the min-max control input can be made small using a well-known disturbance observer technique and only considers the disturbance observing errors. The chattering phenomena can be reduced as small as possible by selecting a high diturbance observer gain. The simulations show that the min-max control with a disturbance observer can reduce chattering phenomena much smaller and guarantee much better robust performance rather than the one without a disturbance observer.