Error-Based Observer of a Charge Couple Device Tracking Loop for Fast Steering Mirror

• Main Authors: Tao Tang, Chao Deng, Tao Yang, Daijun Zhong, Ge Ren, Yongmei Huang, Chengyu Fu
• Format: Article
• Language: English
• Published: MDPI AG 2017-02-01
• Series: Sensors
• Subjects: CCD error-based observer; fast steering mirror; image sensor; light of sight error; low-rate sample; time delay
• Online Access: http://www.mdpi.com/1424-8220/17/3/479

The charge couple device (CCD) tracking loop of a fast steering mirror (FSM) is usually used to stabilize line of sight (LOS). High closed-loop bandwidth facilitates good performance. However, low-rate sample and time delay of the CCD greatly limit the high control bandwidth. This paper proposes an error-based observer (EBO) to improve the low-frequency performance of the CCD tracking system. The basic idea is by combining LOS error from the CCD and the controller output to produce the high-gain observer, forwarding into the originally closed-loop control system. This proposed EBO can improve the system both in target tracking and disturbance suppression due to LOS error from the CCD’s sensing of the two signals. From a practical engineering view, the closed-loop stability and robustness of the EBO system are investigated on the condition of gain margin and phase margin of the open-loop transfer function. Two simulations of CCD experiments are provided to verify the benefits of the proposed algorithm.