Design of Discrete-Time Multivariable Adaptive Repetitive Control Systems

Abstract

There exist many applications of repetitive control on the factory floor, such as industrial robots and machine tool systems. Since most of the existing repetitive control systems are based on the so-called internal model principle, the system needs to include the internal model of the repetitive reference signals, which is usually higher order model. So it is difficult to apply the adaptive pole placement control because the controller needs to be higher order and a large number of controller parameters need to be estimated online. In this paper we propose a design of adaptive repetitive control systems that are capable of arbitrary pole placement. The proposed controller is based on the two degrees of freedom controller with repetitive feed-forward and adaptive feedback controllers. The adaptive feedback controller is also able to reject unknown disturbances by estimating the internal model of the disturbances. The method is applied to a SCARA-type robot and its effectiveness is experimentally examined.