High-Precision Control System Design for a Servo Actuator Based on Optimized Command Shaper

Servo actuator provided with harmonic drive gearing has been used for positioning loads in many applications. In industrial applications, high-precision motion systems not only require high speed specifications but also high precision. However, these mechanisms involve non-linear disturbances and transmission errors which degrade their performance. Proportional controller cascaded with proportional-plus integral controller (P-PI) is used as an efficient controller in many applications, but it fails to provide good performance when applied to high precision motion systems equipped with harmonic drive gearing. Accordingly, reshaping the velocity command of the inner loop of the feedback system is proposed in this study using gain-delay-shaper and based on state feedback. Parameters of the introduced shaper have been obtained using genetic algorithm (GA) optimization. The proposed scheme has been verified using numerical simulation. In order to illustrate the effectiveness of the proposed techniques, the results have been compared with those of other control systems such as conventional P-PI controllers.