基于误差的观测器在光电跟踪系统中的应用

Error-based observer control of an optic-electro tracking control system

对于光电跟踪系统来说,图像传感器例如电荷耦合器件(CCD)只能够探测脱靶量即偏差信息,而无法得到目标运动轨迹,所以,大多数情况下在目标跟踪回路不能直接实现前馈控制,这限制了系统的闭环跟踪性能。本文采用了一种基于误差观测器的等效前馈控制方法来提高运动平台光电跟踪系统的跟踪性能。该方法是在原有的反馈控制回路的基础上加入一个观测前馈通路,通过优化前馈滤波器提高闭环性能。由于是基于最终的视觉误差的观测,该方法对目标跟踪和扰动抑制同时起作用,既可以应用到地基跟踪也可以应用于运动平台上。前馈滤波器没有采用简单的一阶低通滤波器而是选择Q31滤波器。仿真和实验表明,与传统控制方法相比,这种基于误差观测器的控制方法能够有效提高系统的低频跟踪性能。

For an optic-electro tracking system,an image sensor such as charge-coupled device(CCD)cannot provide target trajectories except for line-of-sight(LOS)error.Thus,it is difficult to achieve direct feedforward control for the tracking loop,which determines the closed-loop performance.An error-based observer(EBO)control of a CCD-based tracking loop is proposed to enhance the tracking performance for an optic-electro tracking system on moving platforms.The EBO control can be plugged into an existing feedback control loop.The closed-loop performance of the CCD-based control system can be improved by optimizing the feedforward filter Q(s).Because this EBO method relies only on the final LOS error,it benefits the control system both in disturbance suppression and target tracking and it can be applied to an optic-electro tracking system in moving platforms as well as in ground platforms.An optimal Q31 filter rather than a low-pass filter is improved for this EBO control.Simulations and experiments show that the tracking performance is effectively enhanced in low frequency compared to traditional control methods.