Research on Whole-spacecraft Vibration Isolation based on Predictive Control

摘要

Launch vehicles will impart high levels of vibration to satellite during launch. Whole-spacecraft vibration isolation is a better choice to reduce the magnitude of launch dynamic loads. In this paper, active vibration isolation technology based on predictive control for whole-spacecraft vibration isolation is studied. Considering the special environment of the rocket, pneumatic isolation system is applied. In order to improve the dynamic characteristics of the isolation system, a cascade control with double loop structure and predictive control algorithm for pressure tracking control of inner loop are proposed. A pneumatic servo system exhibits strong non-linearity. To resolve this problem, the control method of multi-models combined with MPC is put forward and applied in this paper, where piecewise linear models, on which controllers are built, are obtained by integrating the models with data at the work points. To enhance the tracking speed, a strategy of switching ahead is proposed, whose feasibility and effectiveness are proved by experiments. In addition, by resetting the predictive horizon and the weighting matrices of the MPC algorithm, influences of the considerable time delay, which is caused by a long pipeline, on the control system performance are effectively suppressed. With these newly proposed approaches, the pressure tracking performance is significantly improved. Thus with this design, the real-time pressure tracking can be guaranteed and so that the active control system can work at higher frequency range. The experiment results of isolation system with the double loop controller showed that the overshoot appears near the natural frequency was decreased greatly.