Research On Key Technology Of Line-Of-Sight Stabilization Of Photoelectric Tracking Platform

As a high-precision tracking servo system,the photoelectric stabilization platform can not only effectively isolate the disturbance received by the carrier under the moving state,so that the tracking equipment installed on the platform can maintain the Los stability,but also prevent the equipment from losing the target due to some disturbance during the working period.It has the function of accurately pointing to the target.Due to more and more application fields of optoelectronic tracking system,it is expected that the optoelectronic tracking platform will be more flexible,so that the target can be tracked stably in any case.However,the stable platform will be affected by the carrier itself and the external environment,and the accuracy of the actual system is not easy to improve.Therefore,exploring and studying advanced strategies is of great significance to improve the target tracking ability and disturbance suppression ability of the Los of the stable platform.In this thesis,the servo control system will be taken as the research object to improve the control performance of the stable platform,and the advanced control strategies and methods will be studied.The specific research contents are as follows:(1)Based on the mechanism analysis of the photoelectric tracking platform,its mathematical model is constructed,and the equations of the whole system are listed.At the same time,the model is simplified into a second-order link after a series of sorting and simplification,and the state space expression is given,which lays a foundation for the research of Los stability control strategy.(2)It is very important to obtain the differential information of the input signal in the photoelectric tracking servo system.Combined with the finite time theory,this thesis introduces the hyperbolic sine function when constructing the acceleration function,and designs the finite time hyperbolic sine tracking differentiator.The designed tracking differentiator can input any order derivatives,and effectively suppress the noise.It has advantages in target tracking accuracy and response speed.The simulation results show that the designed finite time tracking differentiator compound control has a good effect of obtaining differential signals.(3)Considering that the photoelectric tracking servo system will be affected by the external environment and the internal interference of the system,the tracking accuracy and robustness will be reduced.In order to improve the tracking accuracy of the stable platform,an improved disturbance observer(NDO)is proposed to estimate and compensate the system disturbance based on the designed finite time tracking differentiator;A high-order terminal sliding mode compensator is designed to further compensate the unmeasured state of the disturbance.The stability of the system is proved by Lyapunov function.Simulation results show that the proposed strategy can reduce the chattering caused by the traditional sliding mode control.(4)In order to improve the precision of the photoelectric tracking servo system,combined with the advantages of sliding mode control,a sliding mode disturbance observer is designed to estimate and compensate the disturbance.A sliding mode controller is designed for the dynamic part of the system to further compensate the deficiency of disturbance estimation and enhance the robustness of the control system.The stability of the system is proved by Lyapunov function.The simulation results show that the proposed method has certain advantages.