Fast and high-precision tracking technology for image-based closed-loop cascaded control system with a Risley prism and fast steering mirror

Abstract

The Risley prism's compact structure, dynamic responsiveness, and high tracking accuracy make it ideal for photoelectric image tracking. To realize fast and high-precision tracking of the target, we propose an image-based closed-loop tracking cascade control (IBCLTCR-F) system using a single image detector that integrates the Risley prism and fast steering mirror (FSM). Firstly, We propose a cascade control input-decoupling method (CCIDM) for the IBCLTCR-F system to solve the complex problem of coarse-fine control input decoupling in traditional single detector cascaded control systems. Moreover, the CCIDM method ensures that the FSM deflection angle is small and does not exceed its range during the fine tracking process, by using the Risley prism to compensate for the FSM deflection angle. Next, we design the image-based closed-loop tracking controllers of the Risley prism system and FSM system and analyze the stability of the IBCLTCR-F system. Finally, we track static and moving targets through experiments. The experimental results verify the feasibility of the IBCLTCR-F system, the effectiveness of the decoupling method, and the fast and high-precision tracking of the targets.