Research On Friction Compensation Control For Piezoelectric Actuated Servo Tracking Turntable

Piezoelectric motor,as a new type of actuator,is deformed by the inverse piezoelectric effect,and the load is driven by the friction mechanism.It is widely used in precise position control system under severe different requirements,such as high vacuum,strong magnetic field and other occasions.Due to the particularity of aerospace field,the motion control mechanism applied in the corresponding scenarios is facing the challenges of high precision,small size,light weight,strong environmental adaptability and diverse application modes.Piezoelectric motors attracted extensive attention of relevant scholars at home and abroad by their own advantages.However,due to its special working principle,there are still many specific problems in the actual application for piezoelectric motor,such as excessive tracking peak error,strong time-varying and so on.The traditional linear controller has been difficult to meet the high-precision control performance of the piezoelectric motor.There are many kinds of piezoelectric motors.Firstly,the research status of piezoelectric motor applications and drive control technique at home and abroad are investigated.One of the typical piezoelectric motor,named as “linear piezoelectric ceramic motor”,is selected as the research object.Based on the control background of the coarse pointing assembly,this paper aims at LPCM which is used in the PAT system for space laser communication.It is of great significance for the engineering application of piezoelectric actuated servo tracking turntable.In view of the friction,disturbance and thermal drift of LPCM in the control of turntable,the following research work is mainly carried out.Firstly,combined with the design process of the turntable hardware system of the typical PAT system,the drive circuit performance and controller structure of the piezoelectric motor are studied.In order to better explain the "dead zone" and nonlinear phenomena appearing in the control process,the friction characteristics of the LPCM were simulated from the micro-stick slip mechanism.In order to reduce the position tracking error in the control process,especially the error spike generated at the time of the speed zero crossing,the friction compensation control strategy is studied.The advantages and disadvantages of the mainstream dynamic friction model are compared and analyzed.Based on the Generalized Maxwell-slip(GMS)model,the friction model of the system is further improved.The relevant parameters of the pre-slip and sliding phases are identified and the model is verified and analyzed.Feed-forward compensation was performed using the identification friction model,which was compared with the typical motor control method.In contrast,the tracking error spike was effectively reduced.Furthermore,in order to reduce the influence of friction random disturbance,based on the sliding mode idea,an adaptive non-singular terminal sliding mode feedback controller is proposed aiming for avoiding the chattering and boundary problems.The asymptotic stability of the closed loop system is proven by the Lyapunov stability theory.The proposed con can compensate for various changes in friction and disturbance during the movement of the turntable,even though different operating mode such as pointing,scanning and tracking.Finally,in the condition of heavy load and large torque requirement,the continuous working process will cause obvious heat due to friction,which will cause the motor's own dynamic characteristics changed.In order to improve the scope of applicability,this paper compares multiple synchronous driving strategies,and proposes a temperature robust control strategy,which can effectively suppress the attenuation of system performance under obvious temperature uncertainty.The composition,principle and implementation of the piezoelectric actuated servo tracking turntable are systematically introduced in this paper.In the high precision tracking control application of LPCM,some advanced control strategies are proposed,in order to solve the nonlinear disturbance and the temperature drift caused by friction.The proposed control strategies improve the system tracking accuracy,and provide important guiding significance,especially for the motion mechanism driven by piezoelectric motor in the aerospace field.