考虑重心位置不确定性的无尾无人机优化设计

飞机的飞行性能与重心(CG)位置密切相关,尤其是后掠式无尾飞机的重心位置对其飞行性能影响更甚,如果重心位置发生变化,升力分布随之改变,进而影响飞机航时。针对这个问题,从气动布局和设计方法两方面,设计了一种航时对重心位置不敏感的无尾无人机(UAV)。气动布局上,提出了利用螺旋桨动力配平纵向力矩的鸥翼(GW)布局,以减小重心位置变化对升阻特性的影响;设计方法上,采用稳健性优化设计(RDO)理论,分析重心位置不确定时的航时低敏感度问题。以一架小型电动无人机为研究对象,建立了无尾无人机稳健性优化设计环境,包括总体设计、代理模型构造以及稳健性优化。分析结果表明:利用螺旋桨动力配平的鸥翼布局使重心可用范围增加了5%;静安定裕度在5%~15%变化时,该布局可以有效提高航时稳健性。采用稳健性优化得到的无人机几何参数,大幅度降低了重心位置对航时的影响,显著提升了满足约束的概率。

Tailless UAV design optimization under center of gravity location uncertainty

There is a strict connection between aircraft performance and center of gravity (CG) location. This is especially true for a swept tailless aircraft. The shape of lift distribution deviates much from ellipse due to the presence of CG fluctuations. Then it leads to the endurance deterioration. Hence, the tailless unmanned aerial vehicle (UAV) whose endurance is insensitive to CG location is designed. In the current paper, two scenarios namely aerodynamic configuration and design method are presented. In configuration, the gull wing (GW) involving propeller thrust to trim the pitching moment is proposed in order to reduce the effect of CG location variation on lift to drag ratio. While in terms of method, the robust design optimization (RDO) theory is applied to solving the problem of insensitive endurance under CG location uncertainty. A small electric-powered UAV is taken as a case study. The RDO environment is established including UAV conceptual design, surrogate model construction as well as robust optimization. The analytical results show that the proposed GW configuration increases CG admissible region by 5% and the endurance is insensitive when static margin varies between 5% and 15%. The optimal parameters based on RDO largely improve the endurance robustness of tailless UAV. The constraints of UAV design requirements are satisfied with much higher probabilities.