Research On Stable Imaging And Motion Compensation Control Of Photoelectric Imaging System

The photoelectric tracking system has a very good restraining effect on the disturbance of the carrier,and can keep stable under the high-speed operation of the carrier.It is a servo control system with high-precision tracking performance,widely used in aerospace,target tracking,space communication and other fields^[1-2].With the development of the research on the stable platform,the tracking accuracy and imaging accuracy of the stable platform become higher and higher.In practical application,because of the working environment of airborne photoelectric stabilized platform and its own manufacturing process,there are many disturbance sources.Therefore,in order to ensure the stable imaging of the system and improve the tracking accuracy of the system,the following research is done in this paper:Firstly,the structure and dynamic model of the photoelectric tracking system are studied.This paper introduces the theoretical knowledge of coordinate transformation and its knowledge in kinematics,establishes the system model,studies and simplifies the mechanical and electrical model of single channel three-axis platform,and finally obtains the transfer function form and state space form of the photoelectric platform model.Secondly,in view of the problem of stable imaging,the first premise is to ensure the stability of the Los.Based on this analysis,the factors that affect the Los stability of the photoelectric tracking system are analyzed.In order to overcome all kinds of interference in the system and ensure the Los stability,this paper adopts the interference compensation control method,and studies two control schemes.The first one is based on the robust mixed sensitivity control theory The disturbance observer is used to estimate the disturbance of the compensation system,which can effectively suppress the disturbance of the system.In the second scheme,the disturbance compensation strategy is studied from the level of refined anti-interference.A high-order sliding mode disturbance observer is designed to effectively estimate and compensate the disturbance,which is based on the equivalent disturbance of the system and the finite time convergence theory.A high order sliding mode compensator based on Lyapunov theory is designed to further compensate for the UN estimated state of the system.Finally,the effectiveness of the proposed method is verified by simulation and comparison experiments.Finally,aiming at the image rotation problem in the dynamic process of scanning and imaging,the motion compensation control strategy is adopted.In order to overcome this problem,this paper studies the bilateral control in the field of robot teleoperation,and applies this control to the scanning imaging system to improve the transparency of the two systems and solve the image rotation problem.On this basis,in view of the target tracking problem,in the bilateral control structure,this paper proposes a predictive sliding mode control algorithm.Combined with the generalized prediction theory,a sliding mode surface with predictive performance is designed,which can effectively improve the tracking speed of the system.The controller of the system is designed by using the combination of the double power approach rate and the fast approach rate as the approach rate,in order to reduce the chattering problem of sliding mode control,a new power function is proposed to replace the switching function in the controller,and the influence of the thickness of boundary layer on the stability accuracy of the system is used.In the boundary layer,the arctangent function is used,outside the boundary layer,the power of sliding mode surface is used,and the appropriate boundary is selected Layer thickness can improve the tracking speed of the system on the premise of eliminating the chattering of the system.At last,the validity of the control method is verified by the simulation.