Two-stage sliding mode controller for vibration suppression of a flexible pointing system

The performance of pointing systems mounted on top of a vehicle can be affected by the bending vibrations as the vehicle runs on a bump course. In order to improve the pointing performance, the vibrations of the pointing structure should be suppressed. In this paper, a non-linear controller is designed to control the tip position of the pointing system while actively suppressing the vibrations. To cope with high-order dynamics and non-linearity of the plant and the hydraulic actuating system, a two-stage sliding mode controller is designed. The desired actuating pressure is obtained in the first stage and then the input current to the hydraulic servo system is computed to generate the pressure. The simulation results show the effectiveness of this scheme and the improvements obtained in pointing accuracy.