Performance Analysis And Control Design For Mechatronic Servo System At Low Speed

The performance of mechatronic servo-system deteriorates significantly when it worksat low speed, which has proposed a difficult problem for the researchers in the field ofservo control. The purpose of this paper is to study an effective method to improve thetracking performance at low speed of servo-system, which consists of permanentmagnet synchronous motor (PMSM). This paper firstly analyzes the effect brought bythe quantification of feedback signal and the quantification of motor driver anglemeasurement signal. Meanwhile, a general method is proposed to analyze the trackingerror of the quantified feedback system when it tracks a ramp signal. Moreover, a newmethod is proposed to restrain the rate ripple caused by the quantified feedback signal.Then the performance impact of the disturbance torque is analyzed including motorripple torque and friction torque when servo-system running at low speed. In terms ofthese analyses, a control model of the ultra-low speed servo-system is built. Finally,based on this control model, based on which a series of control methods are adopted,including an open-loop compensation to restrain the alternating disturbance torque, adisturbance observer to restrain the friction torque and a Hinf robust controller toconstitute a close-loop system. Last, it is proved through experiments that thesemethods can improve the performance of servo-system at low speed effectively.