An anti-windup rate-varying integral control applied to electromechanical actuator

This paper introduces a novel integral-based controller to correct steady-state error as well as to improve trajectory tracking in position control of a rotary actuator. For this aim, linear and nonlinear modeling of a rotary electromechanical actuator via conventional P-D controller has been described followed by investigation of nonlinear element's effects. The model has very good agreement with experimental results. Then, for trajectory tracking improvement and especially to reduce steady-state error induced by external disturbance, different integral based controllers such as PID, PI-D, and I-PD have been considered. Moreover, the problem of integrator saturation (integral wind-up) has been solved by modified rate varying integral method. It has been showed that a PI-D controller with modified rate varying integral can best match controlling requirements, as well as having enough simplicity for analogue implementation. Also, as a new method, it was suggested that for rate-varying integral calculation, the error rate signal could be replaced by error signal. Doing so, not only former advantages were hold, but more simplicity in controller implementation was gained. Simulation results have shown the effectiveness of the proposed method.