多旋翼无人机减振分析与实验

针对多旋翼无人机机身系统振动过大导致飞行状态不稳的问题,基于有限元仿真技术与实验方法,进行了减振分析。通过频率分析,确定系统振动过大的原因为固有频率与激励频率耦合导致的共振现象,且共振频点的模态振型包含一阶挥舞、一阶摆振和二阶摆振振型。提出了优化机身壳体截面形状的设计方案,在不增加额外质量的情况下,将一阶挥舞、一阶摆振和二阶摆振振型对应的频点分别提高37.23%、22.47%和18.43%,有效规避了机身共振现象。仿真实验证明,提出的有限元仿真与实验结合的减振分析思〖BHDWG8,WK10YQ,DK1*2,WK1*2D〗〖XCMWL.TIF;%129%129〗听语音 聊科研与作者互动 路及优化设计方法,可为旋翼无人机减振设计提供参考依据。     

The year of the drone misinformation

This paper challenges the widely held view in the research communities around the world that US drone strikes on the Pakistan's north-western border area with Afghanistan lead to large-scale civilian casualties and are unpopular in that tribal area. As an example of that view the author analyses a recent research report, ‘The Year of the Drone’, produced by the New American Foundation, and argues that sources of the report are questionable and doubtful. The author, who is a native of the border area with Afghanistan and has lived almost all of her lifetime in the area, informs that the drone attacks are popular in the region and the reports about large-scale civilian casualties are baseless. She provides some evidence in support of her argument and cautions the researchers against the uncritical acceptance of the notions, like the drone attacks are unpopular or have killed civilians.     

多旋翼无人机模型预测抗扰避障制导

多旋翼无人机的自主避障是完成复杂任务的基础,避障的效果直接影响无人机执行任务的效能。针对存在外部扰动的无人机避障问题,提出了一种基于模型预测的抗扰避障制导律设计方法。通过设计干扰观测器对系统动态中的外部干扰进行了估计,并基于李雅普诺夫函数方法设计辅助制导律用于建立稳定性约束条件。结合前两者与模型预测控制,在模型预测控制优化求解中考虑无人机与障碍物的关系,根据所设计的制导律求解水平线速度与偏航角速度指令实现无人机的避障。对所提出的避障制导律进行数值〖BHDWG8,WK10YQ,DK1*2,WK1*2D〗〖XCLQX.TIF;%129%129〗听语音 聊科研与作者互动 仿真和实物飞行验证,结果表明了所提方法的有效性。     

基于十字靶标的人控交会对接仿真

为了减轻航天员的负担,提高人控对接成功率,建立人控交会对接仿真系统是很有必要的。通过对追踪飞行器和目标飞行器的动力学模型分析,建立了人控交会对接仿真系统的基本框架,并基于十字靶标进行了相应的仿真实验。实验结果表明航天员经过一定的训练后,可以通过操作手柄控制追踪飞行器的位置和姿态,实现航天器的交会对接。为降低操作的复杂程度,航天员可以只进行位置控制,而把姿态控制交给自控系统,这样手控对接的成功率会更高。     

通信对抗无人机集群侦察区域规划规则研究

侦察区域规划是通信对抗无人机集群智能侦察的首要任务.能否合理规划侦察区域,对通信对抗侦察任务的完成至关重要.通过研究侦察区域规划分配和动态调整流程,结合通信对抗战斗原则和相关军事经验,整理归纳出通信对抗无人机集群进行侦察区域规划的行为规则、判定规则和策略规则,并提出了规则的使用建议,构想了具体应用场景.     

The legality of unmanned aerial vehicles outside the combat zone: a case study of the Federally Administered Tribal Areas of Pakistan

The drone is the latest tool to promote interests of a nation-state. It is clear that USA as well as other major powers anticipate that robotics will play a key role in future warfare. Today, more than 70 countries have already acquired drone technology and many others are desperate to join the ranks. This urge for drone technology will ultimately lead to a “boundless and borderless war without end.” In the case of Pakistan, the US drone campaign has raised some important issues regarding how their use could, or should, be regulated in the future. This article analyses the legal issues raised by the US's use of drone technology in non-combat zones, such as Pakistan. It is argued that a reckless disrespect of Pakistan's sovereignty has had adverse implications and consequences for the legitimacy of the Pakistani government. Drone strikes have prompted instinctive opposition among the Pakistani population, hurt their feelings and estranged them from the government. This in turn has added to Pakistan's instability and stimulated a ground-swell of animosity toward the USA.     

Sharing security in an era of international cooperation: unmanned aerial vehicles and the United States’ Air Force

The United States’ Air Force (USAF) has developed and used unmanned aerial vehicle (UAV) technology to monitor and assassinate dangerous terrorists in Afghanistan, Iraq, Libya, Pakistan, Somalia, Syria, and Yemen. Currently, there are few countries that possess armed UAV and since the US created much of this technology, the USAF is usually part of the training that automatically accompanies the purchase of its UAVs. The research question this article attempts to answer is, “What is the extent of the United States’ Air Force assistance in the training and proliferation of UAV technology to foreign militaries?”     

From elite consumption to popular opinion: framing of the US drone program in Pakistani newspapers

The United States has conducted armed drone strikes in Pakistan since 2004. While there has been some recent work on Pakistani public opinion about drones, there is very little research on how Pakistan’s media characterize the US drone program. This is an important gap in understanding the determinants of Pakistani popular perceptions of this program. Decades of research has shown that “news framing”, a process by which certain aspects of a complex concept are emphasized in political communications with others played down, influences individual cognition while forming political opinions. In this essay, we address this lacuna by assembling an unprecedented sample of editorials about the drone program from three English newspapers and one Urdu newspaper and analyzing the news frames within them. We next compare the trends in these news frames to public opinion data collected by Pew between the spring of 2009 and 2014. Initially, most Pakistanis were unaware of the drone program, media coverage of the program expanded as drone strikes increased in frequency. While Pakistanis became more cognizant of the US drone strikes, even by 2014 large minorities remained unaware. Pakistani public opinion strongly reflected the top media frames, particularly those that are negative. This is an important finding suggesting that newspaper editorials are a good barometer of Pakistani opinions despite the fact that only information elites rely upon newspapers for political information.