Simple robust speed control scheme for DC servomotors using fuzzy reasoning

The speed control methods using disturbance torque observer have been investigated by many researchers. However, it is difficult to use an observer in a real machine, because the observer has several disadvantages: the selection of the observer´s poles, the complexity of the calculation, and so on. We use a simple estimation mechanism instead of the observer to estimate the disturbance torque. However, this simple mechanism has estimation error for disturbance torque, and the error detracts from the control performance. Thus, we proposed the robust speed control method for DC servomotors considering the estimation error. In order to compensate the estimation error, we combine the equivalent disturbance torque estimator and a feedback controller. The influence of the estimation error is restrained by the feedback controller introducing fuzzy reasoning. The simulation and experimental results confirm the validity of the proposed control technique