Research And Improvement Of PID Control Based On Two-dimensional Aerostatic Bearing Motion Stage

Aerostatic bearing motion stage was a motion platform integrating aerostatic guideway and static pressure supporting,driving,and control technologies,which was generally used in precision and ultra-precision processing and measurement,such as lithography machines.Therefore,aerostatic bearing motion stage was particularly important to improve the stability of the aerostatic bearing motion stage so that aerostatic bearing motion stage can achieve better motion-bearing performance and high motion accuracy of the aerostatic bearing motion stage.In this thesis,the drive system of the aerostatic bearing motion stage was the research object.The drive of the aerostatic bearing motion stage was driven by linear motors installed on the X-axis and Y-axis respectively,which could make the dual axes of the aerostatic bearing motion stage did linear motion.However,linear motors were a particularly complex system,which was difficult to achieve precise control due to some disturbance factors such as changes in external factors.To enhance the use of its control,aerostatic bearing motion stage adopted a combination of intelligent fuzzy control and traditional PID control,aiming to improve platform stability and reduced tracking errors.(1)Based on the control theory of the drived motor of the two-dimensional aerostatic bearing motion stage,this thesis introduces the structure of the aerostatic bearing motion stage and the principle of linear motor(PMLSM)in detail.The idea of coordinate transformation was introduced,and a mathematical model of PMLSM was established under the rotational coordinates d-q axis.The principle of the space vector control method(SVPWM)is summarized and its simulation model is established.(2)Based on the basic theory of fuzzy control,Simulink is used to establish the simulation model of two control algorithms,namely traditional PID control and fuzzy PID control,and analyzed the simulation results.The simulation results showed that the use of a fuzzy PID controller could greatly improve the following effect,shortened the adjustment time,improved the adaptability of the system,and greatly improved the dynamic performance and anti-interferenced ability of the system.(3)In the existing precision aerostatic bearing motion stage hardware platform,the computing power of the industrial computer was limited,to make the fuzzy PID control algorithm realize on the hardware platform,the entire control system of the two-dimensional aerostatic bearing motion stage was studied and improved.Based on the aerostatic bearing motion stage a motion experimental scheme of single-axis motion and two-axis linkage was designed.The single-axis motion experiment takes the X-axis as the experimental axis.Experiments showed that the control error of fuzzy PID was smaller under load change,which proved that the control effect of fuzzy PID was better.The two-axis linkage experiment used the plot method to display the trajectory accuracy,the trajectory was smooth and the fluctuation was small in the experimental results.It showed that the aerostatic bearing motion stage had good stability under the new control algorithm.The simulation results of the fuzzy PID control algorithm designed in this thesis on the hardware platform and the experimental results on the test bench showed that the designed control system had the good adaptive ability and excellent dynamic response performance.The stability of the aerostatic bearing motion stage was enhanced,and the designed controller meets the control requirements,and the research on the control mode of the aerostatic bearing motion stage is of great significance to the industrial control field in China.