Modeling And Simulation Of LOS Stabilization System For UAV Optoelectronic Platform

The visual axis stability control system is an important part of the UAV optoelectronic platform.The UAV is disturbed by the external disturbance during the flight process,causing the visual axis of the photoelectric imaging sensor to sway,resulting in the degradation of the target image quality,affecting the target measurement and aiming of the optoelectronic platformrs tracking accuracy.This paper carried out modeling and simulation around the visual axis stabilization system of the UAV optoelectronic platform,The main contents of the research are as follows:Firstly,the optical platform visual axis stabilization systel was analyzed and modeled.In order to obtain the relationship between the compensated angular velocity of the gyro and the rotation angle of the frame relative to the inertial space,according to the mechanical structure of the photoelectric stability platform,the three coordinate systems of the pedestal,the elevation frame and the azimuth frame are established,and the coordinates are derived between the coordinate systems.The transformation matrix is analyzed by kinematics.Based on the Newton-Eulerian dynamic equation,a dynamic model of the relationship between angular velocity,angular acceleration,moment of inertia and various moments is established for the azimuth and elevation frames.Secondly,the optoelectronic platform visual axis stability control system is designed.The visual axis stabilization loop devices are selected and the mathematical model of each module is calculated;In order to design a visual axis stability controller with excellent performance,the fuzzy control theory and the classical PID control theory are combined to design a parameter self-tuning fuzzy PID controller The simulation verifies that the fuzzy PID controller has better control performance than the fuzzy controller and PID controller in the visual axis stabilization loop.Aiming at the problem of insufficient anti-interference ability of the stable loop,the velocity based disturbance observer(VDOB)is used to observe the external disturbance,compensate the external disturbance,and adopt the fuzzy PID and VDOB composite control in the stable loop.Experiments verify that VDOB in the stability control system greatly improves the isolation effect of the control system on low frequency disturbance signals.Then,the gyro signal denoising method based on Kalman filtering is studied.As the angular velocity measuring component,the gyro affects the accuracy of the visual axis stability control system.In order to reduce the influence of gyro noise on the stability accuracy,the time series method is used to model the gyro signal,and the Kalman filter is used to denoise the gyro signal.The simulation experiment proves The Kalman filter noise reduction improves the performance of the boresight stability control system.Finally,the experimental verification of the visual axis stability control system was carried out.The visual axis stability control system is simulated in MATLAB/Simulink environment.The experimental results show that the dynamic response performance of the control system is good,the stability accuracy is less than 50?rad,which satisfies the stability requirement of the system;The tracking loop position controller is designed and the tracking loop is simulated.The experiment proves that the tracking performance of the stable tracking loop is good;The algorithm is transplanted to controller of the visual axis stable optoelectronic platform,and the accuracy test is performed on the swing table.The test results show that the maximum angular offset of the visual axis stability control system is 36.4?rad,which indicate that the system has high accuracy of stability and the stability of the visual axis stabilization control system is good.