Platform Construction And Experimental Research Of Precision Macro/Micro Coupling Air-floating Motion System

With the continuous improvement of system positioning accuracy requirements in high-end application scenarios,especially in the field of integrated circuits,the traditional rotating motor-driven ball screw movement method is no longer sufficient to meet the current development requirements.The air-floating motion platform is based on the macro/micro-coupling two-stage drive mode and air suspension support.It is a new type of precision positioning system that can overcome contact friction and travel limitations.It has the characteristics of no friction,no pollution and high precision.Therefore,it has become the mainstream trend to use the air-floating motion platform to replace the traditional motion table to ensure the motion accuracy.Based on this,this paper studies the structural design,support technology,dynamic characteristics,control system,control simulation and experiment of the air-floating motion platform.The main research work is as follows:(1)Research the high-precision air bearing motion system at home and abroad,and design a large-stroke precision positioning platform based on the porous static pressure gas bearing.Compared with the existing platforms of the same type,the selfdesigned precision air flotation platform mainly has two characteristics.On the one hand,it adopts the macro-micro coupling two-stage positioning method,which cannot only solve the contradiction between the long movement stroke and high positioning accuracy of the traditional positioning mechanism.On the other hand,the floating bearing technology can also improve the creeping effect and heating phenomenon caused by mechanical friction.(2)Structural design,theoretical calculation and experimental research on the rectangular porous hydrostatic gas bearing of the air flotation platform.Firstly,the performance test table of the porous hydrostatic gas bearing is built,and the material property experiment,the bearing capacity experiment and the static stiffness experiment are completed,and the static stiffness of the AT1 and AT2 porous bearings were obtained as 13 N/μm and 8 N/μm respectively.Secondly,the Adams simulation dynamic model of the air-floating support motion platform is established,and the frequency characteristics analysis of the air-floating platform is completed,and the sixth-order modal frequency of the large-travel air-floating precision positioning platform is obtained.Finally,the test of the force hammer excitation is carried out,and the dynamic stiffness of the air-floating platform in the vertical and horizontal directions was calculated to be 13.3 N/μm and 5.5 N/μm,respectively.(3)Establish the coupled mathematical model of the voice coil motor,the brushless DC motor and the ball screw,and carry out the coupled control simulation.For the precise positioning of the voice coil motor,the neural network nonlinear PID controller is designed to have higher positioning accuracy and robustness than the traditional PID controller,and the simulation and experimental control accuracy reaches sub-micron level.The motion situation of the two-stage control of the micromovement stage and the macro-moving stage are analyzed,and the following experiment and simulation are carried out under the condition that the macro-moving stage adopts the PID control.The results show that under the premise of no mechanical collision,the positioning accuracy of the macro-moving stage has no effect on the positioning accuracy of the micro-moving stage.(4)Build the control system of the precision air-floating motion platform,and carry out the test experiment of the motion positioning accuracy of the air-floating platform.Using DSP28335 as the control chip,the driver of brushless DC motor and voice coil motor are designed.The software design mainly includes the program development of the upper/lower computer.The upper computer is responsible for instruction transmission and data storage,and the lower computer is responsible for processing the displacement data of the laser displacement sensor and the grating ruler.The experimental results show that the developed control system has strong response and computing ability.