Fault-Tolerant Controller Design for Reusable Launch Vehicle

A fault-tolerant controller design for reusable launch vehicles (RLVs) is discussed in this paper. The control precision of RLVs is very important, since it must be ensured that an RLV’s speed reaches zero while flying to the target point. More seriously, the rocket’s thrust system may suffer from faults, so the fault-tolerant control of RLVs is very important. The landing dynamic model of RLVs is very complex, and the thrust is coupled with time-varying states, which make the controller design of RLVs very difficult. Based on the specific control requirements of rocket landing, the control design problem is first transformed into a normal model in this paper. Then, considering potential thrust faults, an optimal fault-tolerant controller is designed using reinforcement learning. Considering sensor faults and actuator faults, this paper presents the corresponding fault-tolerant controller design method. Considering that the analytical problem of the proposed fault-tolerant controller is difficult to solve, this paper presents an approximation method for the analytical solution based on a neural network. The simulation results demonstrate that the proposed controller ensures the safe and stable landing of the rocket in both nominal and fault scenarios.