A survey of guidance,navigation, and control systems for autonomous multi-rotor small unmanned aerial systems

This survey paper presents a holistic perspective on the state-of-the-art in the design of guidance, navigation, and control systems for autonomous multi-rotor small unmanned aerial systems (sUAS). By citing more than 300 publications, this work recalls fundamental results that enabled the design of these systems, describes some of the latest advances, and compares the performance of several techniques. This paper also lists some techniques that, although already employed by different classes of mobile robots, have not been employed yet on sUAS, but may lead to satisfactory results. Furthermore, this publication highlights some limitations in the theoretical and technological solutions underlying existing guidance, navigation, and control systems for sUAS and places special emphasis on some of the most relevant gaps that hinder the integration of these three systems. In light of the surveyed results, this paper provides recommendations for macro-research areas that would improve the overall quality of autopilots for autonomous sUAS and would facilitate the transition of existing results from sUAS to larger autonomous aircraft for payload delivery and commercial transportation.     

超声法纳米颗粒悬浮液粒径测量中温度影响的实验研究

针对医药、化工领域高浓度纳米悬浮液颗粒粒径超声检测中温度影响,采用超声衰减谱法(UAS)对体积浓度30%的纳米铟锡金属氧化物(ITO)水性悬浮液在循环流速800 r/min,温度298～358 K时颗粒粒径分布进行实验。结果表明:温度升高,超声幅值A减小,超声衰减系数增大,颗粒中位径D50增大,颗粒系分布曲线整体朝大颗粒方向偏移,但是分布宽度保持稳定的趋势。同时,将室温(298K)测量结果与CPS离心沉降颗粒测量仪对比,结果较吻合。通过线性回归的方法修正温度对测量结果的影响,超声衰减法能够应用于358K的高温下高浓度纳米颗粒检测。     

大容量Email系统的分布式设计与实现

在大用户量的情况下,该文提出了Email系统的一个快速认证整体解决方案,旨在为类似问题提出解决思路。     

防御无人机系统的威胁(译文)——跨部门安全委员会的最佳实践

本报告为美国联邦行政部门和机构提供了关于防止恶意无人机操作威胁的最佳实践、经验教训和建议的指导。无人机的发展是一项重大的技术进步。除了娱乐和商业用途,还被使用于支持消防和搜救行动,监测和评估关键基础设施,通过向偏远地区运送紧急医疗物资实施救灾,并协助边境安全工作。然而,无人机也可用于恐怖分子、犯罪组织和个体行为者的恶意阴谋。ISC在设计基准威胁(DBT)报告中详细说明了对抗无人机的威胁,这是一个日益受到关注的问题。对抗无人机使用包括敌对监视、走私、破坏和武器化。从网络安全的角度来看,对手可能将无人机作为移动平台,以中断或修改数字服务,或获得对数据系统未经授权的访问。     

从UAV到UAS——无人机系统及光电载荷发展的思考

主要围绕无人机到无人机系统及其相应配套光电载荷的发展进行探讨,在无人机系统方面,通过多个可能的未来无人机系统的协同工作模式强调了无人机系统顶层设计的重要性,建议尽早规范国内的军用无人机市场,制订相关的无人机规范;在光电载荷方面,介绍了其中主流传感器形式随无人机系统发展的相应变化,总结了UAS所要求的高性能、多用途、多光谱/超光谱、通用及开放架构、智能化、小型化等发展趋势,并简单介绍了各自采用的技术手段。     

The iterated extended set membership filter applied to relative localization between autonomous vehicles based on GNSS and UWB ranging

This paper presents a novel Iterated Extended Set Membership Filter (IESMF) with an application to relative localization. For safe operation of formations of automatic vehicles, consistent uncertainty estimates are of crucial importance. Here, a localization filter that provides ellipsoidal regions that are guaranteed to contain another vehicles position is presented. The proposed iterative update step can appreciably reduce the size of the a posteriori state ellipsoid. The idea of using SIVIA as a baseline to quantify conservativeness is introduced. Another novelty is that we take into account parametric uncertainty of the observation equation. The proposed filter is applied to a two unmanned aircraft systems (UAS) localization problem in simulation with observation noise obtained from real sensors. Simulation results illustrate the effective reduction of filter conservativeness by a small number of iterative updates.     

Bauwerksprüfung unterstützt durch neuartige Besichtigungstechniken – Erste Erfahrungen

Structural inspection supported by new inspection techniques – First results The road infrastructure has reached the edge of its service capability by increased external impacts and increasing average age and maintenance measure will be implemented in future to a considerable extent. To carry out the maintenance measures in a technically and economically optimal may, it's necessary to be informed at an early stage as fully as possible about the current state of the structure. For this it's necessary to find and evaluate new innovative techniques to support bridge inspection in accordance with German Standard DIN 1076. Unmanned Aerial Systems (UAS) provide a range of possibilities of photo recording and may thus be used as an auxiliary in bridge inspections. As part of this research project, flights were operated to three bridges and the use of UAS allowed identifying damage to the bridges in question. Given the possibility to operate flights to areas which are not easily accessible as well as time savings during testing offered by the use of UAS, this technology seems attractive for inspections of bridges. The targeted use of UAS will result in reduced service failures and an increase in the quality of results.     

Monocular passive ranging of maneuvering intruder for UAS detect‐and‐avoid

We investigate a planar orbiting intruder passive ranging problem, where an ownship aircraft is moving with a constant velocity and a co‐planar intruder aircraft is conducting an orbiting maneuver. The objective is to estimate the state information of the intruder, such as range, speed and heading, using only bearing measurements of the intruder from the ownship. This is relevant to detect‐and‐avoid applications where an unmanned aerial system (UAS) is equipped with only a monocular camera sensor and needs to determine the range to the intruder. We utilize a filter bank algorithm parameterized with respect to the range, heading, and angular velocity of the intruder's initial states. In previous work, we performed investigations on the effects of parameterizing the filter bank algorithm and the system model using Monte Carlo Simulations. We extend our previous study to include a study on the effects of the ownship speed on the filter performance as well as a Cramer‐Rao lower bound comparison. Since the intruder's motion may be composed of straight legs and orbits, we integrate our filter bank algorithm into an Interacting Multiple Model (IMM) framework for two maneuver models: constant velocity and coordinated turn. We conduct Monte Carlo simulations of the IMM algorithm to study the effects of varying the IMM mixing stage frequency and the off diagonal values for the transition probability matrix. Our simulation results demonstrate the effectiveness of the proposed algorithms.     

改进的蚁群算法在无人机航路规划中的应用

蚁群算法是一种新的源于生物界的仿生随机优化方法。简单介绍了无人机航路规划的基本步骤。针对基本蚁群算法的4个不足,提出了新的改进算法。在算法中设定具体目标和可能经过的威胁点,在信息激素中除了有距离信息还需要增加威胁度信息,并将威胁度设为权重较高的参数指标,在航路规划仿真开始阶段,同时发送多个探路人工蚁。信息激素中的信息是随时更新的,以便于适应战场动态变化。利用MATLAB仿真运算验证了改进算法的有效性。