Passive Fault-tolerant Control Based on Weighted LPV Tube-MPC for Air-breathing Hypersonic Vehicles

Abstract

This paper proposes a novel passive fault-tolerant control method using weighted tube-based model predictive control (Tube-MPC) via polytopic linear parameter varying (LPV) for air-breathing hypersonic vehicles. Firstly, the longitudinal LPV model of the vehicle is established by the Jacobi linearization and tensor-product (T-P). The random drift fault or loss of efficiency fault over the elevator deflection is transformed equivalently into the additional item as bounded disturbance. Based on invariant set theory, a weighted Tube-MPC control method is proposed. In traditional Tube-MPC controller design, the worst case of the fault is generally considered. In order to balance control performance and robustness of the control system, this paper introduces a weighted strategy, where the weighted factor α is used to change the robust positive invariant (RPI) set for incomplete fault set. The robustness of the system is sacrificed, so that the invariant set can be reduced to expand the domain of the nominal control input. In this way, the control performance of the nominal system can be improved. In the actual flight, the states of the hypersonic vehicle system cannot be measured completely, and therefore a polytopic Luenberger state observer is developed to estimate the unmeasured states. The control errors and estimate errors are limited by two incomplete disturbance minimum RPI (idmRPI) sets. Finally, simulations verify the fault-tolerant ability and tradeoff regulating ability of the designed control system.