Research On Trajectory Planning Algorithm Of Three-Axis CNC Platform

In NC machining,the control method of each axis motion is the key to affect the main performance such as motion accuracy and efficiency.Trajectory planning of motion is one of the main methods of motion control.A reasonable trajectory can be designed to achieve high efficiency and optimal time.In the case of limited constraints,the trajectory of each state of motion is obtained through algorithm planning and the axes are processed and machined according to the trajectory.According to different performance requirements and sporting needs,design the corresponding trajectory planning algorithm,so that the movement can meet the requirements.In order to improve the precision of the last position of the movement and reduce the error during the movement,a third-order asymmetric point-to-point linear trajectory planning method is proposed.On the basis of the third-order symmetrical motion,the constraint conditions on the jerk and acceleration in the accelerating and decelerating phases are changed respectively,so that the motion trajectories of the accelerating and decelerating phases are asymmetric.The movement stages of the movement are analyzed,the expression of the state quantities of each node in the course of the movement is deduced,and the time of each movement stage in the movement process is obtained according to the constraint conditions to obtain the movement track.In order to verify the influence of the algorithm on the motion accuracy,the constraint condition of acceleration and acceleration in the acceleration and deceleration phase is adjusted so that the speed of the deceleration phase is reduced.Simulation and experiment were carried out on the computer software and the DC servo motor,respectively.The results show that the algorithm can improve the position accuracy of the end of motion.In order to realize the requirement of changing velocity in the process of uniform motion,an S-shaped trajectory planning method with initial velocity is proposed.The time in each phase determined by the motion state quantity of each constraint condition,and based on the planning which is accelerating first and slowing down later or slowing down first and slowing down later.The simulation on the computer software verifies that the algorithm can meet the requirements of motion variable speed and ensure the boundary conditions.In order to meet the requirement of moving to a specified position at a specified time,a trajectory planning algorithm based on the concept of optimal control with limited terminal time is proposed.According to the needs of the construction of the corresponding performance indicators,by minimizing the performance index to solve the optimal control law and the optimal trajectory.And run the track on the computer software to meet the location and time requirements.