Adaptive suppression of wideband multi-frequency beam jitter in image-based piezoelectric tip-tilt stages

This paper presents an adaptive wideband multi-frequency control (AWMC) strategy aimed at suppressing beam jitter, which is caused by unknown wideband multi-frequency disturbances in the line-of-sight (LOS) stabilization system based on piezoelectric tip-tilt mirrors. The beam jitter suppression is transformed into the optimization of multiple parallel peak filters, which are achieved through Youla-parameterized observer-based control with a series-parallel architecture. An online identification model of perturbation parameters based on the normalized unbiased gradient criterion was constructed using the tilt error of the LOS, and the filter bandwidth was adaptively adjusted in combination with the least mean squares algorithm. In addition, a cascaded filter was innovatively designed to counteract the system delay effect, which enhanced the system stability. Theoretical analysis and experiments indicate that this approach notably improves the LOS stabilization and disturbance suppression in the system.