Research on simultaneous localization and mapping for AUV by an improved method: Variance reduction FastSLAM with simulated annealing

At present, simultaneous localization and mapping (SLAM) for an autonomous underwater vehicle (AUV) is a research hotspot. Aiming at the problem of non-linear model and non-Gaussian noise in AUV motion, an improved method of variance reduction fast simultaneous localization and mapping (FastSLAM) with simulated annealing is proposed to solve the problems of particle degradation, particle depletion and particle loss in traditional FastSLAM, which lead to the reduction of AUV location estimation accuracy. The adaptive exponential fading factor is generated by the anneal function of simulated annealing algorithm to improve the effective particle number and replace resampling. By increasing the weight of small particles and decreasing the weight of large particles, the variance of particle weight can be reduced, the number of effective particles can be increased, and the accuracy of AUV location and feature location estimation can be improved to some extent by retaining more information carried by particles. The experimental results based on trial data show that the proposed simulated annealing variance reduction FastSLAM method avoids particle degradation, maintains the diversity of particles, weakened the degeneracy and improves the accuracy and stability of AUV navigation and localization system.     

Clustered coverage orienteering problem of unmanned surface vehicles for water sampling

This study investigates a clustered coverage orienteering problem (CCOP), which is a generalization of the classical orienteering problem. The problem is widely motivated by the emerging unmanned techniques (eg, unmanned surface vehicles and drones) applied to environmental monitoring. Specifically, the unmanned surface vehicles (USVs) are used to monitor reservoir water quality by collecting samples. In the CCOP, the water sampling sites (ie, the nodes) are grouped into clusters, and a minimum number of nodes must be visited in each cluster. With each node representing a certain coverage area of the water, the objective of the CCOP is to monitor as much as possible the total coverage area in one tour of the USV, considering that overlapping areas provide no additional information. An integer programming model is first formulated through a linearization procedure that captures the overlapping feature. A two-stage exact algorithm is proposed to obtain an optimal solution to the problem. The efficiency and effectiveness of the two-stage exact algorithm are demonstrated through experiments on randomly generated instances. The algorithm can effectively solve instances with up to 60 sampling sites.     

无人作战的人机融合：挑战与出路

无人作战对于人和机器两个要素的融合提出了巨大的挑战。一方面,无人作战独特的作战模式和作战环境对于自然人的能力素质构成严峻挑战,高度智能化的作战系统运行速度、海量的数据信息日益挑战人类的反应能力和决策能力,虚拟的、远程的、与现实战场隔绝的作战环境日益挑战人类的心理素质。另一方面,机器的高度智能化虽然有利于更好地发挥潜在的作战能力,但也不可避免地带来战争失控和道德沦丧的风险。破解人机两个维度的挑战,实现人与机器的深度融合,一方面要利用增强技术从物理、生理、心理三个层面加速提高人类的能力素质,另一方面是强化机器人的伦理安全设计,坚守人类对机器人的控制底线,规避机器人失控和战争“非人化”的道德风险。     

固体药燃气逆向喷流热防护有效性分析

针对高超声速飞行器逆向喷流介质供应,采用固体药燃烧产生的燃气作为喷流的介质,来减小供应系统的质量与体积。采用数值计算的方法对高速飞行器球头逆向喷流流场进行数值模拟,分析不同飞行条件下高温燃气对球头热防护的影响。研究表明,采用高温燃气会减弱逆向喷流的热防护效果,但是对比无逆向喷流的驻点热流,最大热流仍然存在大幅度的下降。通过调节喷流压力,在不增加喷流质量的情况下,高温燃气逆向喷流可以取得与常温介质一致的热防护效果。针对6马赫数以上的飞行,现有的固体药燃气温度能够对飞行器头部实现有效的热防护。     

电驱动车辆反馈线性化自适应滑模滑移率控制

针对驱动和制动工况下电驱动汽车的滑移率控制这一强非线性和不确定性控制问题,提出了一种基于反馈线性化的自适应滑模控制(ASMC)方法。针对车辆驱动、制动工况下的车轮滑移率进行了动力学分析,建立了统一的状态方程。充分利用系统已知模型和参数,采用线性化反馈消除非线性变化的控制量增益系数的影响,通过对反馈项增益参数的自适应调整,适应附着路面不确定参数变化的控制要求,克服系统控制中存在的主要非线性和不确定性部分,对于系统难以建模描述部分,视为扰动,利用滑模控制抑制系统该部分的不确定性因素,同时保证系统响应的快速性,并对算法进行了Lyapunov稳定性分析。最后,以某型电动汽车为对象进行了仿真分析,结果表明采用ASMC控制系统动态响应快、精度高、抗扰能力强,对路面参数变化具有较强的鲁棒性,同时输出控制量抖振小。     

无人舰艇技术及军事应用研究

随着无人飞机的大量研发和广泛应用,无人化智能武器越来越受到世界各国的重视。在海洋争端愈演愈烈的今天,世界军事强国又纷纷把目光投向海上无人作战舰艇,无人舰艇技术得到突飞猛进的发展。近期,美国高调宣布将在中国南海打造以"无人飞机"和"无人舰艇"为骨干的"无人军团",以期全面遏制我海军的行动,加强无人舰艇技术研究已迫在眉睫。从世界无人舰艇发展历程出发,详细阐述了无人舰艇的技术特点和应用前景,重点分析了我军无人舰艇发展应用对策。研究表明,无人舰艇作为未来海航作战中不可忽视的力量,必将走俏未来战场,深度改变战争格局。     

多约束下的高超声速飞行器三维非线性自适应末制导律

面向多约束下高超声速飞行器末制导过程中的通道耦合、参数扰动、模型失配等突出问题,设计一种适于高超声速飞行器的三维非线性自适应末制导律。为了模型描述的完整性和简洁性,引入视线旋量和旋量速度的概念,并基于此建立三维制导参考模型和实际系统的表达式;为了保证制导律的鲁棒性和自适应性,基于自适应控制理论,设计一种三维非线性自适应制导律;通过数学推导证明了该制导律的稳定性。该制导律能够从理论上克服高超声速飞行器末制导面临的通道耦合、参数扰动、模型失配等突出问题,满足多约束制导要求。仿真结果验证了所设计制导律的有效性。     

应用边界交叉法的高超声速滑翔飞行器多目标轨迹优化

针对高超声速滑翔飞行器复杂约束条件下多目标轨迹设计问题,基于边界交叉法和伪谱法提出多目标轨迹优化方法。分析高超声速滑翔飞行器复杂约束轨迹优化问题的特点,提出多目标轨迹优化问题。采用边界交叉法和伪谱法将多目标轨迹优化问题转化为一组单目标优化子问题,利用非线性规划算法分别求解。在优化过程中,将已求解子问题的解作为下一个子问题的初始值,求解最大横程和最小峰值热流轨迹优化问题。仿真结果表明:所提方法能够有效搜索到优化轨迹的Pareto前沿,可以为高超声速滑翔飞行器轨迹设计提供参考。     

多级电磁线圈发射器时序触发控制策略

为优化多级同步感应线圈电磁发射器性能,以提高发射速度和能量转换效率为检验指标,以影响上述指标的触发时序为优化对象,采用遗传算法建立单级同步感应线圈型电磁发射器触发位置优化数学模型,计算最佳触发位置,通过数值和有限元两种仿真系统对优化结果的正确性进行验证。采用该方法对两级以及十级同步感应线圈型电磁发射器的触发时序进行优化研究,并进行仿真验证。为解决仿真系统误差问题,提出采用动子线圈在各级的触发位置和速度作为控制因素的双控触发方式,并研究分析仿真过程中触发开关的随机抖动对出口速度误差的影响,得到最佳触发时序控制策略。     

Western drones and African security

While unmanned aerial vehicles (UAVs) have become a standard element of modern armed forces, African countries have been reluctant to acquire remotely piloted aircraft for military purposes until recently. This is mainly due to a lack of industrial capabilities and, for military purposes so far, procurement policies that have concentrated on small arms and light weapons, more prestigious armoured vehicles and combat aircraft. Moreover, counter-insurgency strategies in Africa tend to focus on manoeuvre warfare, co-opting rebels or fighting them using armed proxies. As a consequence, international counterterrorism operations against fanatical and reckless groups like al-Qaeda in the Islamic Maghreb and Boko Haram in sub-Saharan Africa are characterised by a strong dependence on Western forces providing UAV-based reconnaissance and, in some cases for the United States, military strikes by drones. This essay reviews some of the incentives and problems of the use of UAVs in the African context. Given the geographical and military conditions of asymmetric warfare in Africa, and potential problems concerning international law, ethical aspects of the use of arms, and civil–military relations notwithstanding, it is argued that African security forces should develop their own UAV capabilities by intensifying their cooperation with Western armed forces.