Establishment and Simulation of Twelve-Degree-of-Freedom Model for UAV Parachute Recovery System

无人机伞降回收十二自由度模型建立与仿真

School of Aeronautics, Northwestern Polytechnical University, Xi'an 710072, China

Received: 19 March 2019

Abstract

In the UAV parachute recovery process, the UAV and the parachute have always been in the state of dynamic balance, so it is difficult to deal with the constraint between them. In order to solve this problem, the UAV parachute recovery system was divided into three parts:the parachute, riser and UAV. The extension length of riser was obtained by the velocity relationships of the riser connection points. The riser tension was obtained by the product of the elastic coefficient and the extension length of the riser. And it was applied to the parachute and UAV systems respectively. Finally, based on the Newton-Euler equation, the 12-DOF model of UAV parachute recovery system was established, in which the unsteady aerodynamic model of the UAV from the forward flight to the steady descents was established based on the ONERA equation. The simulation and test results shows:the 12-DOF model is consistent with the results of the experimental data, which verifies the accuracy of the 12-DOF model. The 12-DOF model is more accurate than the past 6-DOF model. This model established in this paper can provide reference for the selection of parachute in the UAV parachute recovery system and the determination of the landing point of the UAV.

摘要

在无人机的伞降回收过程中，无人机与降落伞一直处于一种动平衡的状态，因此两者间约束关系的处理将是伞降回收动力学建模的难点。为了解决该问题，将无人机伞降回收系统划分为降落伞、吊带和无人机三部分，通过吊带连接点的速度关系得到吊带伸长量，通过弹性系数与吊带伸长量的乘积得到吊带拉力，并将其分别施加于降落伞和无人机系统，最终基于牛顿-欧拉方程建立了无人机伞降回收系统十二自由度模型，其中采用ONERA方程建立无人机由前飞过渡到稳定下降阶段的非定常气动力模型。通过数值仿真与实验数据对比可以发现：十二自由度模型和实验数据的结果一致，验证了该模型的准确性。十二自由度模型相比于六自由度模型精度更高。文中所建模型可为无人机伞降回收系统中降落伞的选取、无人机着陆点的确定提供参考。