UAV无动力螺线下滑纵向自适应非线性制导律设计

Design of Longitudinal Adaptive Nonlinear Guidance Law for Unpowered UAV Helix Gliding

针对无人机失去推力后如何跟踪一条螺线下滑路径的纵向制导问题,提出了一种纵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纵向制导律;其次将其转化为一个二阶黏性阻尼振荡系统,并由此证明了制导律的稳定性;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纵向路径跟踪过程。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。

For the longitudinal guidance problem that how to track a helix path when the UAV loses power,we present a method of the nonlinear adaptive longitudinal guidance to track a given falling spiral. Firstly,the guidance law is obtained with the geometric relationship. Secondly,the guidance law is transformed to a two- order viscous system with damping and oscillation,based on which the guidance stability is proved. Then we design an adaptive scheme for the guidance laws in order to improve the convergence time of the system and its anti- disturbance rejection capability. Finally the presented method is used to track the falling spiral when the UAV loses the thrust. The simulation results and their analysis show preliminarily that,compared with other non- adaptive method as,the proposed method improves the tracking accuracy of the system,despite being constantly subjected to wind disturbance.