Research On Precision Positioning Servo Control System Based On Voice Coil Motor

With the progress and development of science,the importance of precision positioning technology in various fields has gradually become prominent.Voice coil motor is a special kind of linear motor,which has the advantages of simple structure,small size and fast response,and is widely used in precision positioning servo control systems.In order to realize the control of the precision positioning servo system of the voice coil motor,this paper mainly studies three aspects: the mathematical model of the voice coil motor,the design of the motion control board,the control strategy and the realization of the software algorithm.Firstly,the mathematical model of the voice coil motor is established by combining the level equation and force balance equation of the voice coil motor.And based on the experimental requirements of the voice coil motor servo control system in this paper,the control strategy is determined,and the asymmetric S speed curve based on convolution for speed regulation to reduce vibration is introduced in detail.Designed and produced motion control board for voice coil motor servo control system,and the DSP chip is used as the core processor,which is responsible for the realization of the control algorithm,the data exchange and the driving of the voice coil motor.The FPGA chip is used as the co-processor,which is responsible for the acquisition and processing of the position feedback signal and realizes the communication with the main processor.Then complete the design of each part of the program in the DSP chip and the FPGA chip,and implement the improved PSO-BP neural network PID controller for position loop control in the DSP chip.When the swarm algorithm optimizes the initial network weight of BP neural network PID,the inertia weight is changed from the commonly used linear decreasing to random weight.The simulation experiment shows that compared with the BP neural network PID and the standard PSO algorithm,the optimized BP neural network PID not only has a smaller overshoot but also a shorter adjustment time.Finally,combined with the motion control board and control strategy,corresponding servo systems are built for the voice coil motor air floating motion platform and the voice coil motor vertical he final motion platform,and the repeated positioning accuracy test experiments with and without load are carried out respectively.The experimental results show that in the control experiment of the voice coil motor air floating motion platform,its two-way repeatable positioning accuracy is 67.5nm when there is no load,and its two-way repeatable positioning accuracy is 69.8nm with a 1kg load,both of which meet the design goal of repeat positioning accuracy less than 100 nm.Also in the control experiment of the final motion platform of the voice coil motor,the two-way repeatable positioning accuracy without load is 80.2nm,and with 5kg load is 85.6nm,both of which also meet the design target of the platform’s repeatable positioning accuracy of less than 100 nm.