Research On Robust Control Algorithm For Line Of Sight Stabilization Of UAV Opto-electronic Platform

During the flight course of unmanned aerial vehicle(UAV),the line of sight(LOS)stabilization system is affected by various disturbances and cause itself jitter,which not only affects the image quality,but also makes it difficult to extract information of target,and even unable to complete the tasks of reconnaissance,tracking and others.Therefore,it is necessary to seek effective control algorithm to improve the stability of the system.In this paper,the LOS stabilization system of a UAV opto-electronic platform is researched integrated with robust control algorithm.The mam contents are as follows:1.The functions and structure of the LOS stabilization system for UAV opto-electronic platform are studied.Aiming to solve the problem of self-locking in two-axis and two-frame platform,the two-axis and four-frame platform is chosen as the platform framework of the control system.The disturbance factors are analyzed for designing the overall scheme of LOS stabilization system.In order to establish a complete LOS stabilzed loop,the components are selected according to the overall scheme and performance requirements of the system.And the model of each component is built.2.For the sake of the parameter uncertainty of the controlled object,a robust control strategy based on Quantitative Feedback Theory(QFT)and PID is designed to ensure the stability of the LOS of the control system.QFT is used as the main controller to overcome the parameter uncertainty of the controlled object and make the control system meet the robustness requirement for LOS stabilized platform of UAV.In order to further improve the response performance of the system,PID is used to realize the dynamic compensation of QFT.The experimental results show that the proposed algorithm can meet the requirements for LOS stabilization of UAV and is superior to the QFT method.3.The wavelet filtering algorithm is conducted to smooth the noise signal caused by gyroscope in the LOS stabilized loop,which may reduce the accuracy.Since the parameters of the wavelet function have different effects on the filter,different filters are compared and the threshold,wavelet function and wavelet decomposition scale suitable for the system are determined through wavelet filtering experiments on the collected signals.The experimental results indicate that the selected wavelet filter can effectively smooth the noise signal of gyroscope.4.The LOS stabilization system of UAV opto-electronic platform is simulated in MATLAB/Simulink environment to verify the performance of the robust control algorithm.By comparing the effects of QFT and PID controller,it is shown that QFT is more robustness.The effects of QFT and compound parallel robust control are analyzed,and the accuracy test is performed on the swing table,the results suggest that the compound parallel robust control algorithm can meet the requirements of the LOS stability index of the control system,and realize the robust control of the LOS stabilized platform of a UAV with high precision.