An adaptive frequency disturbance rejection control for an inertial reference unit under unknown disturbance

The inertial reference unit (IRU) can provide a reference beam for the line-of-sight stabilization system to achieve precise pointing and tracking. The reference beam leaves the IRU with minimal jitter and determines the accuracy of acquiring, tracking and pointing system. When the vehicle is moving, the disturbance usually gathers around one frequency. Meanwhile, the resonance introduced by the flexure support of the IRU seriously affects the stabilization accuracy. In this paper, an extended state observer with frequency adaptation is proposed to improve the performance of disturbance rejection. An auxiliary filter is used to optimize the disturbance frequency estimation and improve the control bandwidth. Simulation results and experimental data verify the effectiveness of the proposed method.