Robust Position Control of DC Servomotors with Identifing the Estimation Error of Equivalent Disturbance Torque Observer by Fuzzy Reasoning

Abstract

The position control ability of DC servomotors is affected by parameter variations and disturbance torque. A mathematical plant model is usually used for controlling DC servomotors, however, accurate parameter measurement is very difficult and parameters vary with operating conditions, for example, temperature rise or saturation effects.In recent years, the DC servocontroller using the equivalent disturbance torque observer which compensates parameter variations and disturbance torque has been proposed, high-performance control of the servomotor has been achieved. However, the estimated disturbance torque by the equivalent disturvance torque observer has estimation error, therefore, the control method taking account of estimation error is necessary.In this paper, the robust position control method of DC servomotor with the equivalent disturbance torque observer and the feedback controller is proposed. The estimation error for disturbance torque is identified by fuzzy reasoning. The influence of estimation error is restrained by the adaptive feedback gain law using the identified estimation error.The useful features and validity of the proposed control method are confirmed by computer simulations and experiments.