Research On Disturbance Observation And Fine-stability Control Technology Of Motion Platform Electro-optical Tracking System

With the increase in demand for electro-optical tracking systems in the motion platform and the popularity of the application,the system in the motion platform should be with more stringent indicators and technology.Due to the movement of the carrier,the environment,and other factors can affect the line of sight(LOS)stability of the system,disturbance rejection techniques for electro-optical tracking systems are particularly important.In this paper,for the problems faced by the composite axis structure of the motion platform electro-optical tracking system in tracking and disturbance rejection.A disturbance fusion feedforward technique based on inertial angular rate and image fine detector and a double-order fine-stability control algorithm based on error fusion are proposed respectively.The effectiveness of the algorithms is proved by theoretical analysis and experimental results.This paper firstly introduces the disturbance distribution of the electro-optical tracking system in different application scenarios and researches the development status of stable tracking platforms and stability control technology at home and abroad.Aiming at the problem of tracking and stability control of the motion platform electrooptical tracking system,the operating principle of the composite axis is analyzed.The LOS stability in inertial space is an important prerequisite for target tracking,and the factors limiting the disturbance rejection performance of the composite axis system are analyzed.Two ways of stabilizing the fast-steering-mirror(FSM)by inertial sensors are introduced.The inertial sensor measurement signal contains disturbance information and the target motion.The key to the fine stability control of the composite axis system is the precise decoupling of the above two signals.The disturbance feedforward control theory and the bandwidth expansion technique of multi-sensor data fusion are introduced,and a disturbance fusion feedforward control technique based on inertial angular rate and image fine detector is proposed.The low-frequency target signal of the inertial angular rate signal is filtered using a high-pass filter.The low-frequency disturbance that needs to be supplemented is obtained from the fine image detector by a complementary low-pass filter,and the two signals are fused.The compensation of the disturbance is achieved by a feedforward approach using a high-bandwidth FSM.The complementary filter design combines the effect of low-frequency signal delay and the suppression effect of the high-pass filter on the target motion frequency.Through simulation compared with the traditional composite axis,the disturbance rejection bandwidth of the system is effectively increased from 13 Hz to 75 Hz,which significantly improves the system’s mid-frequency and high-frequency disturbance rejection performance.For the inconspicuous improvement of the disturbance suppression in the lowfrequency band since the fine image detector decouples the small amount of lowfrequency disturbance,a double-order fine stability control algorithm based on error fusion is proposed.The algorithm utilizes a low-pass filter to obtain disturbance and target residual information at low frequencies through the coarse image detector instead of fine image detector.A high-pass filter is used to obtain high-frequency disturbance in the inertial angular rate signal,which are compensated by a FSM.The impact of image detector delay on the system is also analyzed.The pure delay link of the coarse image detector leads to signal phase lag.By comparing different delay times,it is concluded that the smaller the delay,the more obvious improvement of the disturbance rejection ability of the system.Compared with the gimbal loop,the disturbance rejection bandwidth of the system is increased from 26.5Hz to 112 Hz.The target tracking bandwidth of the system is increased from 0.36 Hz to 1Hz,and the tracking performance at the target frequencies is improved by 20 d B.Finally,the algorithms are verified effectively by simulating disturbance experiments of gimbal and shaking table.