Robust Controller for Servo Systems

Abstract

One of the main objectives of feedback control is to obtain a robust system that can provide accurate control in the presence of large variations in parameters. Adaptive controllers are used for such a purpose but mainly they require extensive computations and may not compensate large uncertainties in the system parameters. This paper presents a new approach for robust control. The developed concept is illustrated using a DC servo motor control system. An auxiliary compensating loop is developed to provide a stabilizing signal that eliminates the effect of system parameters variation while at the same time the primary servo controller is in action. The stabilizing signal is calculated using a simple and straight forward control law. The results obtained from system simulation illustrate clearly the effectiveness of the proposed scheme under large parameter variations in servo motor. The system with the suggested controller exhibits robust behaviour for variations in both the effective inertia and friction. The closed loop roots showed minimum sensitivity under large system parameter variations.