Periodic Adaptive Learning Control For The Position Servo System With Friction

The electric servo system has been widely used in various manufacture,for its simple structure,light weight and low maintenance cost.However,with the development of the science and technology,the requirement of the servo system tracking accuracy is increasing.Due to the restriction of nonlinear interference factors centered on the friction disturbance,the conventional control methods are hard to further improve the tracking performance of servo system.Therefore,the design of friction compensation controller with modern control theory to improve the servo system tracking performance is of vital significance in theory and practice.The research object of this thesis is the electric servo system.By analyzing the effects of the friction on system and considering the periodicity of the friction in periodic reciprocation motion,a Model Reference Adaptive Controller and Periodic Adaptive Learning Controller(MRAC-PALC)is proposed.The main content is as follows:First of all,by analyzing the effects of the friction on the servo system,the position servo system model with LuGre friction is established.And the double friction observer is designed,accordingly.Secondly,to reduce the effects of friction interference on the servo system,a MRAC-PALC is proposed and the stability of the system is analyzed via Lyapunov stability theorem.In order to verify the effectiveness and superiority of the proposed controller intuitively,the controller performances of the Model Reference Adaptive Controller(MRAC),conventional PD controller and MRAC-PALC controller are compared via simulation.The result shows the proposed MRAC-PALC controller-based system can compensate the friction disturbance moment effectively.Thirdly,considering the negative influence of the controller input saturation on the dynamic performance of servo system,an extra anti-saturation item is added and the improved MRAC-PALC controller with anti-saturation ability is designed.Lyapunov stability theorem proves the stability of the improved MRAC-PALC controller-based system.The simulation with input saturation analyzes the effects of input saturation on the performance of the servo system and verifies the anti-saturation of the improved MRAC-PALC controller.Finally,to further verify the performances of the proposed MRAC-PALC controller and improved MRAC-PALC controller,considering the equivalency between improved MRAC-PALC controller and MRAC-PALC controller without input saturation,a comparative experiment between improved MRAC-PALC controller,MRAC controller and PD controller is conducted using Permanent magnet synchronous motor(PMSIM)experimental platform.By introducing the frequency domain analysis and ITAE index,the effectiveness and superiority of the proposed controller are proved.