Improving the stabilization of electro-optical pointing systems with an additional actuator

Abstract

Precision-stabilized pointing systems (PSPs) are commonly used in civil and military domains for line-of-sight (LOS) stabilization and control. PSP stabilization accuracy and speed-tracking performance are affected by various factors, such as the modal behavior of the vehicle/structure, stiffness of the components, dynamics of payloads and environmental disturbances. The literature shows that various investigations on hardware and controller design have been conducted to improve the stabilization accuracy of PSPs. This study addresses a critical challenge in dual-actuator pointing systems: the trade-off between fast slewing performance and precision stabilization. High-speed maneuvers drive the inner-axis actuator to its saturation limits, preventing it from suppressing disturbances. Furthermore, the resulting high-amplitude mirror excursions lead to barrel distortion and warping effects, which arise from intrinsic mirror characteristics and optical phenomena. To solve this problem, we propose a novel control strategy based on an error-dependent variable gain for adaptive reference signal shaping. In the conducted studies, the unmodified reference signal, the modified reference signal, and a general filter were applied, and comparisons were made between these methods. The variable-gain, our suggested approach, was used in the reference signal modification method to reduce the system’s overall settling time and the error between the axes during the direction. The desired performance requirements for the system are fast settling times and low inter-axis error values. The normalized stabilization test results for both the elevation and transverse axes are examined, and it is observed that the stabilization sensitivity of the PSPs’ elevation and transverse axes improves with increasing disruptive frequency.