Combined PID and adaptive nonlinear control for servo mechanical systems

Abstract

This paper presents a robust control method for servo mechanical systems, based on a mixed PID/adaptive algorithm. A second-order linear dominant model is considered with an unmodeled part of dynamics that is possibly nonlinear and time-varying. The PID part of the controller is designed to stabilize the dominant model. The adaptive part of the controller is used to compensate for the deviation of the system characteristics from the dominant linear model to achieve performance enhancement. The advantage of the proposed controller is that it can cope with strong nonlinearities in the system while still using the PID control structure which is well known to many control engineers. The proposed control scheme guarantees the boundedness of the system states and parameter estimation. © 2004 Elsevier Ltd. All rights reserved.