无人机无动力滑行横向自适应非线性制导律设计

Design of the lateral adaptive nonlinear guidance law for unpowered unmanned aerial vehicle gliding

中文关键词  无动力  自适应  非线性制导  粘滞阻尼震荡  Hebb学习法则

英文关键词  unpowered  adaptive  nonlinear guidance  viscous damped oscillations  Hebb learning law

中文摘要

      当无人机失去推力后, 可将其视为滑翔机. 在这种情况下, 长周期模态起主导作用, 这使得无人机调整飞行速度达到稳定状态的时间变长, 从而导致横纵向制导之间相互存在较为明显的影响. 更重要的是无动力情况下, 无人机对风扰动变得更加敏感. 针对这一特殊状态, 如何使无人机跟踪某条给定的下降螺旋线, 本文提出了一种横向自适应非线性制导方法. 该方法首先利用几何关系推导出横向制导律; 其次将其转化为一个二阶粘性阻尼振荡系统, 而该系统的特性与其自然频率有关; 然后为改善制导系统的收敛时间以及抗干扰能力, 设计了一种制导律的自适应方案; 最后将所提出的方法用于无人机失去推力后螺线下降的横向路径跟踪过程. 仿真结果表明, 与非自适应制导方法相比, 无论有或无常值风扰动, 所提出的方法均可提高系统的跟踪精度.

英文摘要

      Unmanned aerial vehicle (UAV) is regarded as a glider when it loses its power. Because the phugoid mode plays a major role, it makes the regulating time to the steady state become longer. That will cause the obvious influence between the longitudinal and lateral guidance. The more important is that UAV without power is more sensitive to the wind. This paper presents a method of the lateral adaptive nonlinear guidance to track a given falling spiral. First the guidance law is obtained by the geometric relationship. Then the guidance law is transformed to a two-order viscous system with damp and oscillation, while the characteristic of this system is related to the system’s natural frequency. The authors design an adaptive scheme for the guidance laws in order to improve the convergence time of the system and its anti-wind ability. Finally the presented method is used to track the falling spiral when the UAV loses the thrust. The simulation results show that, compared with other non-adaptive method, the proposed method improves the tracking accuracy of the system, no matter whatever there is the constant wind disturbance or not.