The research and design of high precision contour machining for multi-axis motion control

In multi-axis machining, the processing of curves and surfaces in the two-dimensional space and the three-dimensional space requires the coordinated motion of each axis, and the machining accuracy is determined by both the tracking error and the contouring error. Tacking and contouring accuracy resulting from not only the high performance controller of each axis to improve the tracking accuracy but also the well controlled coordination motion of each axis to improved contouring accuracy. The sliding mode control and contour error compensation is adopted to achieve the target First, to improve the tracking accuracy, an adaptive PID controller based on sliding mode control which consists of a PID controller and a fuzzy compensator is designed for each axis. The adaptive PID controller can automatically online tune the PID controller gains using the gradient descent method, and the fuzzy compensator is designed to compensate the output of the PID controller. Second, to improve contouring accuracy, considering the mutual dynamic effects among each axis, a contour error compensator is designed to calculate the compensation of each axis by the contouring error and to carry out the contouring error compensation. The simulation results indicated that the proposed control method has a good performance on both tracking and contouring accuracy in three-axis machining.