Attitude Stabilization of Rocket Elastic Vibration Based on Robust Observer

This paper proposes an approach to suppressing the elastic vibration and propellant sloshing in attitude control of a high slenderness ratio rocket. The main method is to combine a variable-gain robust observer with a variable structure controller for the purpose of attitude stability and elastic vibration suppression. A variable-gain robust observer is designed to reconstruct the attitude variable and complex multi-order elastic state. In this way, each order elastic vibration can be transformed into an additional attitude with the attitude characteristics of the rocket, which is easy to control. The reconstructed rocket body with an additional attitude is treated as the input of the designed variable structure controller to output the control signal. Under the simultaneous action between the variable-gain robust observer and variable structure controller, attitude stability is achieved for the rocket considering multi-order elastic vibration, and the propellant sloshing in the launch vehicle storage tank can be suppressed simultaneously. According to the simulation results, the proposed method produces a satisfactory stabilization outcome on each order of elastic vibration (especially low-order elastic vibration) and is better than a single variable structure controller.