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针对以X-33为对象的三自由度高超声速飞行器,采用相邻可行轨迹存在定理(NFTET)设计了容错制导律以解决再入段执行器发生故障的轨迹重构问题。在标称情况下采用预测校正算法生成满足再入过程约束和终端约束要求的再入轨迹;当执行器发生故障时,飞行器气动参数、结构和舵面力矩都可能发生不可预测的变化,原先的轨迹不再满足制导要求,因此需要设计新型容错制导律。针对实际再入制导模型,基于NFTET设计容错制导算法对轨迹进行重构,得到满足故障情况下制导任务的可行轨迹。从仿真结果中可以看出,容错制导算法生成的新轨迹重新回到了约束范围之内,轨迹呈收敛趋势,使得高超声速飞行器从故障恢复到正常飞行状态,提高了飞行器的自主容错能力。
Aiming at the X-33 hypersonic vehicle with three degrees of freedom, fault-tolerant guidance law is designed by the NFTET to solve the trajectory reconstruction problem of the reentry actuator. In the nominal case, the predictive correction algorithm is used to generate the reentry trajectory that satisfies the reentry process constraints and the terminal constraints. When the actuator fails, the aerodynamic parameters, structure and rudder torque of the aircraft may change unpredictably. The original Trajectories no longer meet the guidance requirements, so the need to design a new fault-tolerant guidance law. According to the actual reentry guidance model, the fault location guidance algorithm based on NFTET is used to reconstruct the trajectory, and the feasible trajectory to meet the guidance task under the fault condition is obtained. From the simulation results, it can be seen that the new trajectory generated by the fault-tolerant guidance algorithm is back within the constraints and the trajectory is convergent, which makes the hypersonic vehicle recover from the fault to the normal flight state and enhances the autonomous fault tolerance capability of the aircraft.