Research And Application Of Galvanometer System Based On Sliding Mode Control

The galvanometer system is a servo control system with a high-precision and high-speed vector,which is an important basic component for realizing laser radar beam expansion.However,the complex and changeable working environment of lidar,such as disturbance and noise,makes the galvanometer system easily affected during the scanning process,which reduces the accuracy of laser beam expansion.To overcome these unfavorable factors,the following work is carried out in this article:(1)Focusing on the design goal of tracking scanning of the galvanometer system,the framework of the galvanometer control system was designed.Then the mathematical model of the galvanometer servo system was established,which lays the foundation for the subsequent galvanometer position tracking control algorithm.(2)Aiming at the chattering and slow convergence problems in the traditional sliding mode control,the traditional reaching law was analyzed,and the contradiction between the convergence speed and chattering in the process of the system state approaching the sliding mode surface was pointed out.From the perspective of optimizing the reaching law,an improved power reaching law was proposed,which designed a fast-converging exponential function term based on the double-power reaching law.It not only accelerates the convergence speed of the whole approach process,but also realizes the smooth transition of the sliding surface,and reduces the chattering phenomenon.Finally,in order to make the motion state of the system converge to the equilibrium point in a finite time,the fast nonsingular terminal sliding mode function(FNTSM)was selected,and the FNTSM position tracking controller based on an improved power reaching law was designed.The performance comparison experiment and anti-disturbance comparison experiment show that the controller effectively improves the anti-disturbance ability and tracking ability of the system.(3)In the discrete-time domain of the galvanometer servo system,a discrete sliding mode control based on the Kalman filter(KF-DSMC)was proposed to solve the problem that the disturbance and noise in the working environment exacerbate discrete sliding mode chattering.Based on discrete linear sliding mode control,the Kalman filter was designed to estimate the change of the real state quantity of the galvanometer system,reduce the uncertainty disturbance,and weaken the chattering problem.It also avoids the complexity of the discrete linear sliding mode control and improves the engineering application value and transplantation efficiency of the KF-DSMC algorithm.The simulation results show that the KF-DSMC algorithm can deal with the influence of different types of external disturbances on the tracking scanning of the galvanometer.(4)The design framework of the galvanometer control system adopted the“FPGA+STM32” dual-core architecture,which realized the software and hardware design of the desired angular position generation control subsystem,the drive motor position calculation and control subsystem.As the main controller,the FPGA chip performs tasks such as control of the drive motor and position calculation due to its advantages of parallel and high-speed signal processing.As a co-processor,the STM32 chip performs tasks such as generating the required angle position and communicating with the upper computer due to its rich peripherals and serial processing advantages.Finally,a galvanometer control experimental platform was established,and the KF-DSMC algorithm was transplanted into the galvanometer control system to conduct the desired angular position tracking experiment.The results show that the working performance of the galvanometer control system is stable and achieves the expected design goal of the galvanometer system.