Research On Key Technology Of High Speed And High Precision Air Bearing Motion Stage Control System

As the size of ultra-precision machining is getting smaller and smaller,and the demand for production efficiency is getting higher and higher,the requirements for positioning accuracy and running speed of ultra-precision motion stage are getting higher and higher.General motion stage is challenging to meet the needs of ultra-precision machining,and the development of ultra-precision sports platforms has many technical difficulties.The air bearing stage with no friction,low damping,and other advantages,is the development trend of the ultra-precision motion stage.In this thesis,the key technology of high speed and high precision motion control of air bearing stage is studied.First,the factors affecting the high-speed and high-precision motion of the air bearing motion stage are analyzed,and a closed-loop control loop for high-speed and high-precision motion control is proposed.Improve control bandwidth and stability with PID and filter for high-precision motion control.The acceleration feed-forward controller is used to reduce the system stabilization time and following error of the air-floating motion stage during high-speed motion.The acceleration feedforward coefficient is calibrated and delay compensation is added to improve control performance.The third-order trajectory planning is used to generate smooth trajectory commands,which reduces the impact during the movement and achieves rapid stability.Since air bearing motion stage using an H-type structure,are driven by two motors in one direction.If the motors are not synchronized,the positioning accuracy of the air bearing motion stage will be reduced,and even cause the air bearing motion stage damaged.For the dual-drive synchronous control,a synchronous control algorithm based on model decoupling is adopted.The linear motion of the two motors is transformed into the displacement of the beam centroid and the rotation of the beam around the centroid,which realizes the decoupling of the control object,facilitates the design of the controller,and realizes high-speed and high-precision motion control.The external disturbance force during the operation of the air bearing motion stage will also have a significant impact on the synchronous motion of the motors.The disturbance observer is used to suppress the system disturbance and reduce the synchronization error.The synchronization of the control signals and the feedback state between the various axes of the air-floating motion stage are essential for the performance of the control system.The distributed clock synchronization function based on EtherCAT realizes the synchronization of control signals and feedback data,which improves the performance of the control system.The effectiveness of the algorithm is verified by simulation analysis.A prototype was developed.The experimental test results show that the performance meets the technical requirements of the design and realizes high-speed and high-precision motion.