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

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.