Research On LOS Stabilization Technology Of Shipborne Photoelectronic Tracking Platform

With the rapid development of science and technology,the carrier of the photoelectric tracking platform is gradually changing from a fixed base to a moving platform.Due to the complicated maritime environment,the ship will swing motion under the influence of wind,waves and currents.Since the photoelectric tracking platform is fixedly connected to the deck,it will move the same with the motion of the hull,which causes the visual axis to deviate from the measured target.Make it more difficult to track the target.In order to reduce the influence of carrier motion on tracking and make the visual axis stable in the inertial space,corresponding methods must be adopted to stabilize the visual axis.In addition,the system is also affected by the unbalanced moment,frictional moment and model parameter changes caused by the motion of the hull.In this paper,aiming at these two major issues,the visual axis stabilization technology of the photoelectric tracking platform is researched.First,the composition,working principle and working mode of the photoelectric tracking platform are introduced,and the internal disturbance factors of the system and external carrier disturbances that affect the stability of the visual axis are analyzed,including the influence of the translation and rotation of the hull on the direction of the visual axis.Then,starting with the servo system that controls the movement of the tracking platform,a three-loop current-speedposition closed-loop control is designed,and on the basis of the single-speed loop,the encoder differential feedback speed inner loop is introduced to form a double-speed loop structure.,Isolation and robustness angles of single and double speed loops are compared to illustrate its application advantages.Then,the problem of the angular velocity of the base disturbance caused by the movement of the carrier is addressed.In complex sea conditions,the ship’s swaying motion has a greater impact on the stability of the visual axis,and only the speed gyro feedback cannot achieve the high-demand visual axis stabilization effect.Therefore,based on the dual-speed loop structure,the data provided by the inertial navigation system is passed through the coordinate After the transformation,the feed forward to the velocity inner loop,but there is still residual disturbance after the inertial navigation feed forward,and then the rate gyro feedback is used to form the velocity outer loop to compensate for the remaining disturbance,forming the inertial navigation feed forward and gyro feedback composite control,which improves The effect of restraining the shaking of the carrier is achieved,and a higher accuracy of the stabilization of the visual axis is achieved.Finally,the system is subject to moment disturbances such as unbalanced torque,frictional torque,wind resistance,and changes in the model parameters of the controlled object of the system.An adaptive backstepping sliding mode control is proposed for the speed inner loop of an electro-optical tracking servo system to overcome the influence of torque disturbance and model uncertainty within the system.Due to the advantage of sliding mode control that is not sensitive to the influence of system disturbances and parameter changes,However,the improved control effect will also bring about chattering problems.In order to solve the chattering problem,the RBF neural network is introduced to estimate the disturbance to form an adaptive backstepping sliding mode control,which improves the dynamic anti-disturbance ability and robustness of the servo system.