A Dual-Loop Position Servo System Based on Position and Speed Parallel Control Structure

Traditional position-speed-current loop nested structure cannot satisfy the requirements in industrial applications with high trajectory tracking accuracy and fast dynamic response like vehicle-used laser radars and wafer stages. Thus, a position and speed parallel control structure is proposed to achieve high tracking accuracy in this paper. First, the mechanism analysis and parameters tuning method of the classical PI-Lead structure and two traditional three-closed-loop structures, P-PI-PI and PI-P-PI are given. In the proposed position and speed parallel control structure based on improved active damping, the speed controller with proportional control is connected in parallel with the position controller of the PI-Lead structure to improve the stability of the PI-Lead structure and maintain its accuracy. Finally, comparative experiments between the proposed parallel structure and traditional three-closed-loop structure are carried out on commercial-grade microminiature drivers under permanent magnet synchronous motors, the experimental results indicate that the parallel structure can improve the dynamic response performance effectively and enhance the stability of the system.