ADAPTIVE-CONTROL IN THE PRESENCE OF SATURATION NONLINEARITY

Saturation non-linearities are perhaps the most commonly present type of non-linearities in dynamic systems. It is therefore important for t he controller present to function satisfactorily in the presence of in put saturation. In this paper we present an adaptive controller which leads to satisfactory performance in the presence of magnitude saturat ion of the control input. For both continuous time and discrete time p lants, the adaptive controller is shown to result in global stability if the plant is open loop stable and minimum phase, and local stabilit y otherwise. Robustness properties of the resulting adaptive controlle r are established. The performance is verified through experimental re sults obtained from adaptive control of a precision machine tool axis.