On adjustable and lossless suppression to disturbances and uncertainties for nonminimum-phase laser pointing system

ISA Trans. 2023 May:136:727-741. doi: 10.1016/j.isatra.2022.11.004. Epub 2022 Nov 8.

Abstract

This paper focuses on the nonminimum-phase laser pointing system's disturbances and uncertainties rejection problems on moving platforms. Moving platforms cause a variety of noticeable vibrations that substantially impair pointing accuracy. Additionally, the disturbance-observer-based control approaches currently in use sacrifice the desired disturbance suppression effects, stability margins, or tracking characteristics due to the nonminimum-phase laser pointing system. This paper suggests an adjustable disturbance-observer-based control strategy with dual filters to obtain lossless and adjustable disturbance suppression effects without sacrificing stability margins or tracking characteristics. The closed-loop controller and forward plant are presented to reduce the laser pointing system's nonminimum-phase properties. An additional flexible filter is added to deal with the weakened nonminimum-phase system. Both filters are uniformly proposed depending on various disturbances brought on by moving platforms and work together to accomplish lossless desired disturbance suppression effects. The analyses and experiments show that the suggested approach can accomplish the lossless and adjustable disturbance suppression effects in the nonminimum-phase laser pointing system, which cancels out many more disturbances and uncertainties than the current methods.

Keywords: Adjustable disturbance-observer-based control; Laser pointing system; Lossless disturbances and uncertainties suppression; Nonminimum-phase system.