基于NFTET的高超声速飞行器再入容错制导

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。

Fault-tolerant guidance for reentry hypersonic flight vehicles based on NFTET

A fault-tolerant guidance law using the neighboring feasible trajectory existence theorem (NFTET) for the three-degree-of-freedom model of a hypersonic vehicle X-33 is designed to solve the problem of trajectory reshaping under actuator failures in reentry phase. In the nominal case, the predictor-corrector guidance algorithm is used to generate the reentry trajectory which meets the requirements of reentry process constraints and terminal constraints. When the actuator failures occur, aerodynamic parameters, structure and the torque of surfaces of flight vehicles may change unpredictably, which makes the nominal trajectory not satisfy the guidance requirements of the reentry process. Therefore, it is necessary to design a new fault-tolerant guidance law. For the reentry guidance model, the fault-tolerant guidance algorithm is designed to reshape the trajectory based on NFTET. Then there is a new feasible trajectory which meets the requirements in the fault case. From the simulation results we can see that the reshaping trajectory generated from the fault-tolerant guidance algorithm is within the constraints of scope, shows a convergent trend and makes the hypersonic flight vehicles recover from failures, improving the autonomic fault-tolerant ability of the vehicles.