Disturbance Rejection of the Galvano Scanner System using Sensorless Acceleration Control and Disturbance Torque Compensation

This paper presents a controller design approach to improve the disturbance rejection performance on a Galvano scanner system. This system combined with laser has been widely used in the manufacturing industry, because of its fast response and precise positioning capability. In this system, the reflected mirror is driven by the Galvano motor to position the laser beam to the desired spot. However, due to the asymmetrical mirror structure and the non-ideal mirror connection with the Galvano motor, causing the unbalanced disturbance torque, deteriorate the laser positioning accuracy. To improve the disturbance rejection performance, this paper firstly proposes a disturbance observer to estimate the unknown disturbance and compensate for the low-frequency disturbance. Secondly, a dual observer with disturbance torque compensation is designed for acceleration estimation. Besides, the acceleration feedback control scheme is proposed to suppress the high-frequency disturbance. According to experimental results, the proposed sensorless acceleration control and disturbance torque compensation improve the disturbance rejection performance on a Galvano scanner system.