Acceleration control in a dual-stage inertial stabilization system using embedded-parallel-based repetitive-peak compensation

Acceleration control demonstrates high sensitivity to nonlinear vibrations in the inertial stabilized motion, usually serving as the preferred choice for observation systems in applications like space optical communications, enabling precise tracking and pointing. However, the stabilization performance is limited by the inadequate gain at mid- to high-frequencies in conventional acceleration control, as well as other nonlinear factors like flexibility and backlash. In this paper, an embedded-parallel-based stabilization methodology is proposed for an acceleration-based dual-stage inertial system to achieve additional notch shaping of the sensitivity function. The essence of this method involves implementing a repetitive controller with a low waterbed effect, paralleled with a peak compensator at a specific frequency to establish an efficient and rapid compensation structure. Relying exclusively on a repetitive controller proves effective in eliminating uncertain periodic vibrations, acting as a substitute for an infinite number of peak compensators. Incorporating an additional mid- to low-frequency peak compensator, designed based on the priori narrowband vibration spectrum, is considered an auxiliary supplement to the repetitive controller. Crucially, this parallel structure neither destabilizes the system nor imposes significant computational burden. Simulations and experiments were conducted at typical vibration frequencies of 1-4 Hz, and experimental results demonstrated a 35%-48% improvement in acceleration stabilization performance, enhancing the system's capability to reject non-strictly periodic vibrations beyond the control bandwidth.