Observer-based robust control for a flexible launch vehicle

Abstract

This article investigates the problem of robust stabilization for a flexible launch vehicle. Since the launch vehicle suffers from parametric uncertainties, bending modes, and external wind disturbances simultaneously, an observer-based methodology is provided to address these negative factors. The proposed method can guarantee the stability of the closed-loop system and minimize the H∞ performance index. Additional regional pole placement constraints are imposed on the feedback gain matrices to improve the transient performance of the system. A two-step strategy is proposed to solve the involving bilinear matrix inequality problem. Compared with existing methods, which mainly depend on introducing additional constraints to linearize the bilinear matrix inequality conditions, the proposed strategy can reduce the conservatism and is suitable for engineering practice. The simulation results for one operating point and nonlinear model illustrate the validity and effectiveness of the proposed control method.