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《中国航空学报》2022,35(8):193-203
In this paper, periodic event-triggered formation control problems with collision avoidance are studied for leader–follower multiple Unmanned Aerial Vehicles (UAVs). Firstly, based on the Artificial Potential Field (APF) method, a novel sliding manifold is proposed for controller design, which can solve the problem of collision avoidance. Then, the event-triggered strategy is applied to the distributed formation control of multi-UAV systems, where the evaluation of the event condition is continuous. In addition, the exclusion of Zeno behavior can be guaranteed by the inter-event time between two successive trigger events have a positive lower bound. Next, a periodic event-triggered mechanism is developed for formation control based on the continuous event-triggered mechanism. The periodic trigger mechanism does not need additional hardware circuits and sophisticated sensors, which can reduce the control cost. The stability of the control system is proved by the Lyapunov function method. Finally, some numerical simulations are presented to illustrate the effectiveness of the proposed control protocol. 相似文献
164.
《中国航空学报》2023,36(2):76-86
For Unmanned Aerial Vehicles (UAVs) with limited electrical power to achieve effectively anti-/de-icing at the leading edge of the wing, a strategy of ice shape modulation was proposed. Isolated simulated ice shape pieces printed by 3D printing technology are mounted on a NACA0012 finite wing model, and its lift/drag coefficients and suction-side velocity fields are measured by the six-component force balance and the Particle Imaging Velocimetry (PIV), respectively. The ratio of the spanwise length of a single ice shape piece to chord length and the spanwise length of the non-icing area between the two adjacent single ice shape pieces are defined as dimensionless ice shape length (w/c) and dimensionless modulation ratio (w/λ), respectively. The results indicate that for a fixed w/λ, the wing lift coefficient first increases and then drops with increasing w/c, and a peak value exists when w/c is between 0.1 and 0.2. The lower the w/λ is, the higher the wing lift coefficient will be. The periodical variation of the flow separation area along the spanwise direction is attributed on the one hand to the acceleration effect of the flow field in the non-icing area which reduces the separation area, and on the other hand to the cross-flow caused by the streamwise vortices from the non-icing area to the icing area which promotes the mixing of the flow field (similar to vortex generators). The obtained modulation law is verified through flight tests and provides guidance for the use of ice shape modulation scheme for UAVs that cannot be completely anti-/de-icing under severe weather conditions. 相似文献
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本文基于DJI(大疆)精灵4多光谱版无人机能够同时获取地表可见光照片和多光谱影像的特点,提出了使用摄影测量技术构建冠层高度模型(CHM)的方法,并结合多光谱影像应用于红树林分类。将上述方法应用于广东省湛江红树林国家级自然保护区高桥镇研究区,结果表明:基于无人机摄影测量技术构建的红树林CHM与多光谱影像结合后能够大幅提高红树林的分类精度,可替代传统的机载激光雷达数据;DJI精灵4多光谱版无人机数据获取效率高,能够实现高精度的红树林分类,在红树林监测业务工作中具有推广应用价值。 相似文献
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随着科学技术的高速发展,地下领域(如天然洞穴网络、人造隧道和城市地下环境等)逐渐成为人类研究的热点,利用无人系统在地下等复杂场景执行探索、搜索与搜救等任务仍面临着许多挑战.深入分析了美国地下领域无人系统技术发展的模式框架,梳理了快速轻量自主、机械天线和地下挑战赛等DARPA典型研发项目的 研究目标与现状,提炼出地下领域无人系统需要解决的关键技术,在此基础上归纳总结了美国地下领域无人系统的发展趋势.最后,结合国内发展情况提出了地下领域无人系统的发展启示. 相似文献
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《中国航空学报》2022,35(8):158-167
This paper proposes a new reconfigurable intelligent surface based three-dimensional beam tracking method to solve the beam tracking problems for the unmanned aerial vehicle with obstacles in communication channels. The proposed beam tracking method can not only regulate the reconfigurable intelligent surfaces to achieve the beam tracking of the obstructed communications, but also optimize the transmission efficiency of the communication. Firstly, a reconfigurable intelligent surface is proposed, which can correlate the transmission signals by adjusting the phase-shift matrix. Meanwhile, a new communication channel is constructed according to the reconfigurable intelligent surface, which consists of two parts. The first one is the channel between the unmanned aerial vehicle and the reconfigurable intelligent surface, the other is the channel between the reconfigurable intelligent surface and the ground base station. Note that the transmission performance of the communications can be optimized by adjusting the phase shift of each uniform linear array on the reconfigurable intelligent surface. Then, a new beam tracking method for the unmanned aerial vehicle with obstructed communications is proposed on the basis of the reconfigurable intelligent surface. By proposing the mixed genetic algorithm, the estimation accuracy of the azimuth and elevation angles is improved to enhance the performance of the beam tracking. Finally, the simulations are provided to verify the effectiveness of the proposed three-dimensional beam tracking method with reconfigurable intelligent surface. 相似文献