Research On Control Technology Of New Lortzen Suspension Position Platform

With the development of Industry 4.0 era,countries pay increasingly more attentiveness to the development of high-precision industries.In the field of precision measurement,the system-level technology of precision positioning platforms has always been the key to national and national defense basic industries such as aerospace,IC industry manufacturing,and semiconductor technology.Traditional precision positioning platforms mostly use mechanical bearings to support and move.The friction and wear during the movement will continue to affect the actual positioning accuracy with a longtime applying.The traditional mechanical physical contact limits the further improvement of the accuracy of the mechanical positioning platforms.The new suspension positioning stage designed based on the Lorentz force principle has the advantages of no friction,simple principle,high ideal precision,and fast response speed.It is an ideal platform for realizing high-precision suspension positioning.This paper starts at the principle of Lorentz force and magnetic bearing,and successively introduces the structural design and basic suspension principle of the platform.In order to verify the function of the new suspension positioning platform,simulation and semi-automatic positioning are carried out from the perspectives of motion positioning control strategy and power amplifier.Physical research will further verify the feasibility of the prototype Lorentz suspension positioning platform.Taking the Lorentz force magnetic bearing as the research object,the equivalent magnetic circuits method are used to establish the basic magnetic circuit mathematical model of the positioning table,and the current stiffness of the load-bearing and deflection magnetic bearings can be derived.Considering the nonlinear distribution of the gap magnetic density in the deflection process,the electro-magnetic force is analyzed by the integral method to obtain a relatively accurate electromagnetic torque model of the platform.In the motion control system of the Lorentz levitation positioning stage,the motion process mainly includes three parts-levitation,deflection and rotation.The deflection and rotation motions are more complicated than the levitation,and they need to follow the instructions and ensure the accuracy.Therefore,this paper focuses on introduces control strategies for tilting and rotational motion.For dual working conditions and different process requirements,this paper adopts a variety of control strategies.In the state of high adaptive deflection and fast maneuvering,the PID parameters are properly adjusted by adding a binary coding genetic algorithm with a certain amount of calculation,which has more advantages than traditional PID.We design a linear state observer to observe the state of the model,and introduce a Kalman filter to noise-reduce and estimate the dynamic angle signal to improve adaptability and accuracy in the high-precision deflection/rotation state.In order to improve the sampling angular rate bandwidth and accuracy,combined with optimal control by using the MEMS attitude sensor MH1760,the sensor can provide high-fidelity deflection/rotation signals in the time domain and frequency domain when the platform stabilizes deflection/rotation.According to the motion characteristics and basic control method of the Lorentz levitating positioning stage,STM32F407VET6 is selected as the main control chip,and the power supply of the chip is stabilized by linear step-up or step-down voltage regulators such as LM2576 S and MC34063 A and EMI resistance-capacitance filtering,and output by configuring the GPIO port,through the triode MMBT4401 and the logic gate HEF4081 BT for logic level conversion and output PWM signal,DRV8837 PWPR driver chip is used for current direct drive output through PWM input,according to OP07 designed a current feedback loop,combined with LDC1000 EVM to design a displacement detection module,and completed the PCB prototype production.Finally,the Lorentz levitation positioning platform experimental system is built,and the current closed-loop control algorithm is compiled according to the design process,which is realized by digital PID controller.Experiments show that the Lorentz levitation positioning stage has basic levitation and deflection functions,and at the same time verifies the feasibility of the PID control strategy and the PCB hardware board,paving the way for the future development of cutting-edge instruments such as new levitation high-precision positioning.