基于平衡飞行理论的推力故障火箭入轨能力评估与制导方法研究

Equilibrium flight theory-based orbit entry capability evaluation and guidance method of launch vehicles with thrust faults

针对某型运载火箭在大气层外飞行段出现推力异常的非致命发动机故障,提出一种基于平衡飞行理论的火箭入轨能力评估与连续推力制导方法.首先从飞行力学角度对火箭推力故障导致任务失利进行了机理分析;在此基础上建立当地水平坐标系的火箭飞行动力学简化模型,进而提出平衡飞行的解析理论;进一步分析“平衡飞行”与“准平衡飞行”条件,并比较二者最优制导律的差异;接下来,给出了平衡飞行理论应用于推力异常火箭在线评估与决策的方法与流程;最后开展数学仿真,整体揭示了推力损失与入轨能力的关系,综合检验了平衡飞行解析理论的正确性与实用性.该方法寓在线能力评估与最优轨道制导于一体,简便有效,可为推力异常运载火箭的快速自主故障处置提供技术理论支撑.

Considering the nonfatal engine faults(e.g.,abnormal thrust)of a launch vehicle in the outer atmosphere flight phase,a method based on equilibrium flight theory for the evaluation of the vehicle’s orbit entry capability and continuous thrust guidance is proposed.First,the mechanism of mission failure caused by abnormal thrust fault is analyzed from the perspective of flight dynamics;on this basis,the simplified model of launch vehicle flight dynamics is established in the LVLH coordinate system,and the approximate analytical theory of equilibrium flight is provided.The conditions of an“equilibrium flight”and a“quasi-equilibrium flight”are further analyzed,and the differences between their guidance laws are compared.Next,the method and process of the online evaluation and decision-making of launch vehicles with an abnormal thrust are listed.Finally,numerical simulation is performed to reveal the relationship between thrust drop and orbit entry capability,as well as to verify the correctness and practicability of the analytical theory of an equilibrium flight comprehensively.This simple and effective method integrates online capability evaluation and optimal orbit guidance,which can provide theoretical and technical support for rapid autonomous fault handling of launch vehicles with thrust faults.