Research On The Motion Control Of Feed Axis Of Slow Tool Servo Turning Based On Linear Motor

The complex optical surface has broken through the traditional design theory of optical imaging system and greatly improved the performance of the optical system.However,the extremely high precision requirements of optical parts have brought challenges to manufacturing.Single point diamond turning has been widely used because it can directly process optical parts that meet the requirements of optical application.Among which,the slow tool servo technology breaks through the limitation of traditional turning and realizes the turning processing of non-rotary symmetric complex surface.In this paper,starting from the key precision motion control of the linear feed axis in slow tool servo machining,the following work is carried out:(1)The advantages of linear motor direct drive motion are analyzed,after the actual parameters of the linear motor model are obtained through system identification,the PID + feedforward composite controller is designed by the analytic method,and based on the LQ optimal control theory,the firefly global search algorithm is used to complete the tuning of PID optimal control parameters.(2)after analyzing the inherent force ripple problem of linear motor,two different force ripple suppression methods are studied from the perspective of control.The first is to establish a force ripple model and identify the model parameters online for real-time compensation through feedforward.Second,the disturbance observer is used to estimate the force disturbance and make feedback compensation.Finally,combining the advantages of the two methods,a compound force ripple suppression algorithm is designed.(3)The trajectory planning method of slow tool servo turning is studied to generate the servo command input of the linear feed axis.The characteristics of different tool contact discrete methods are compared and analyzed;the effects of normal tool compensation and Z direction tool compensation on feed axis motion are studied;the advantages of PVT interpolation method for free curve machining trajectories are discussed;and the simulation research of turning path planning is carried out with three typical complex surfaces.(4)Relevant experiments were carried out on the open motion control platform based on Power PMAC.Using Simulink's model-based design function,a custom servo interrupt program was built using code generation technology,and the suppression effect of different algorithms on force ripple was compared.Finally,the motion program of the motor is written,to simulating slow tool servo turning for complex surface,and the influence of the speed,interpolation method and surface feature on machining accuracy is analyzed.