Multi-model soft switching tracking control and robust least-squares weighted control allocation for near space interceptor

This paper deals with the multi-model soft switching tracking control (MMSSTC) design problem with a disturbance observer and a new robust least-squares weighted control allocation (RLSWCA) method for the near space interceptor (NSI) with aerodynamic fins and reaction jets. Initially, the flight envelop of the NSI is divided into some small subregions by the fuzzy partition method, a slow-fast loop soft switching model is constructed to represent the NSI system based on the local Takagi-Sugeno (T-S) model, and a disturbance observer is proposed to estimate the unknown disturbance. Then, based on the descriptor system method, a MMSSTC is developed to not only ensure the stability of the closed-loop NSI system, but also achieve a specified control performance. Furthermore, a new RLSWCA algorithm is employed to distribute the virtual control command among the redundant actuators. The purpose of this algorithm is to find the optimal control vector of the actuators by minimizing the worse-case residual, while taking into account of the uncertainty in the control effectiveness matrix and the actuator constraints. Finally, simulation results on the NSI demonstrate the effectiveness of the proposed control scheme.