直升机发动机失效后的定点自转着陆是一项极具挑战的高风险机动科目。该过程要求直升机在能量受限的条件下，克服纵垂向运动的强非线性耦合干扰，实现对预定着陆点的高精度软着陆。针对自转着陆时多轴协调及可用能量自适应方面的不足，设计了一种基于着陆可用能量改进的生物制导自转着陆专家系统。首先，通过分析生物制导Tau理论的运动学特性，结合自转着陆的动态特性，对Tau导数的选取进行了讨论。其次，针对目前自转着陆Tau制导中对未对剩余运动时间进行动态调整的问题，提出了一种以直升机实时可用能量为调整系数的剩余飞行时间自适应估计方法，实现了能量约束下的轨迹规划。随后，交代了所设计专家系统的整体结构及采用的控制律设计方案。最后，基于试飞数据验证的高置信度EC120直升机飞行力学模型，对不同初始纵向距离的着陆过程进行了仿真，结果均实现了垂向速度不大于4m/s的高精度定点着陆。在此基础上，基于状态量变化时间历程分析了初始纵向距离对着陆性能的影响，并针对低能量着陆工况，进一步开展了有无能量衰减系数的对比仿真，结果表明，能量衰减系数的引入提升了最低旋翼转速，降低了触地瞬间的垂向动能。
Forced landing following a helicopter engine failure is an extremely challenging, high-risk maneuver. This procedure demands that the helicopter, under severe energy constraints, overcome strong nonlinear cross-coupling effects between longitudinal and vertical motion to achieve a high-precision soft landing at a predetermined touchdown point. To address the deficiencies in multi-axis coordination and adaptive energy management during autorotation landing, an improved bio-inspired Tau-theory guidance expert system based on available rotor energy is designed. First, by analyzing the kinematic characteristics of the bio-inspired Tau theory and incorporating the dynamic features of autorotation, the selection of the Tau derivative is discussed. Second, to tackle the problem that current Tau guidance methods for autorotation lack dynamic adjustment of the time-to-go, an adaptive time-to-go estimation method is proposed, which uses the helicopter's real-time available rotor energy as an adjustment coefficient, thereby enabling trajectory planning under energy constraints. Subsequently, the overall architecture of the designed expert system and the adopted control law design scheme are presented. Finally, based on a high-fidelity EC120 helicopter flight dynamics model validated against flight test data, simulations of landing procedures at various initial longitudinal distances are conducted. The results demonstrate high-precision pinpoint landings with vertical velocities not exceeding 4 m/s in all cases. On this basis, the influence of the initial longitudinal distance on landing performance is analyzed through the time histories of state variables. Furthermore, for low-energy landing conditions, a comparative simulation with and without the energy attenuation coefficient is carried out. The results show that the introduction of the energy attenuation coefficient raises the minimum rotor speed and reduces the vertical kinetic energy at the moment of touchdown.
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