LQR and Fuzzy Gain-Scheduling Based Attitude Controller for RLV within Large Operating Envelope

Considering the strong uncertainties of aerodynamic parameters and atmospheric environment and the large dynamic variation during the Reusable Launch Vehicle (RLV) reentry process, this paper introduces an attitude controller design method which combines Linear Quadratic Regulator (LQR) with Fuzzy Gain-Scheduling (FGS). The whole operating envelope is divided into several design points firstly. And then, control state deviation based LQR controllers are designed for design points respectively. Thereafter the FGS controller is obtained by the use of Takagi-Sugeno (TS) fuzzy model. In the next step, the 6-DoF nonlinear simulation conveys that the stability of off-design points is guaranteed and the proposed controller is capable of maintaining a satisfactory tracking performance under uncertainties among the operating envelope.