Control Allocation-Based Command Tracking-Control System for Hypersonic Re-entry Vehicle Driven by Hybrid Effecters

The paper deals with a command tracking-control system (CTCS) design problem for plants involving both continuous and discrete effecters, namely hybrid effecters. Firstly, a reaction control system (RCS) model of a hypersonic re-entry vehicle (HRV) is established, and then linearization around the trim points is carried out for both longitudinal-direction and lateral-directional nonlinear models of HRV, respectively. Second, a general command-tracking problem is converted to a regulation problem by constructing a deviation system, and an optimal state feedback controller is designed to generate a continuous torque command. Then, a daisy-chained control-allocation method is applied to assign the torque command between the aerosurfaces and RCS, and an innovative control-allocation strategy of integrating model predictive control with mixed-integer linear programming (MPC/MILP) is proposed to distribute the torque to RCS among thrusters, where the switching-time constraints of the thrusters can be taken into account explicitly. Finally, the proposed control-allocation strategy is demonstrated to the longitudinal angle-of-attack (AOA) CTCS and the lateral-directional bank angle CTCS design for HRV. Compared with MILP, the MPC/MILP control-allocation strategy is more reasonable in on/off switching of the RCS thrusters and effective in reducing the wastage of the RCS fuel. Simulation results using a six-degree-of-freedom (6-DOF) nonlinear dynamics model of HRV show that the proposed strategy is suitable for the CTCS design of HRV driven by both the aerosurfaces and the RCS.