自组网Random Waypoint移动模型节点空间概率分布的研究

Random Waypoint模型是自组网经常使用的移动模型,对这种移动模型下运动节点的空间概率分布进行了研究,得到了一维与二维区域的运动节点空间概率分布的精确公式,解决了自组网仿真模型的一个遗留问题·研究结果为基于Random Waypoint移动模型的自组网理论的推导、证明、仿真与应用提供了理论依据,对基于该模型的自组网仿真具有实践指导意义·

基于Waypoint8的GPS精密单点定位研究

介绍了精密单点定位的基本原理,对IGS精密星历进行了研究,利用Waypoint8软件对精密单点定位精度进行了测试与分析。结果表明:GPS精密单点定位在NEU三维分量上的精度约为20cm。

Reentry trajectory rapid optimization for hypersonic vehicle satisfying waypoint and no-fly zone constraints

To rapidly generate a reentry trajectory for hypersonic vehicle satisfying waypoint and no-fly zone constraints, a novel optimization method, which combines the improved particle swarm optimization （PSO） algorithm with the improved Gauss pseudospectral method （GPM）, is proposed. The improved PSO algorithm is used to generate a good initial value in a short time, and the mission of the improved GPM is to find the final solution with a high precision. In the improved PSO algorithm, by controlling the entropy of the swarm in each dimension, the typical PSO algorithm＇s weakness of being easy to fall into a local optimum can be overcome. In the improved GPM, two kinds of breaks are introduced to divide the trajectory into multiple segments, and the distribution of the Legendre-Gauss （LG） nodes can be altered, so that all the constraints can be satisfied strictly. Thereby the advan- tages of both the intelligent optimization algorithm and the direct method are combined. Simulation results demonstrate that the proposed method is insensitive to initial values, and it has more rapid convergence and higher precision than traditional ones.

Control of Velocity-Constrained Stepper Motor-Driven Hilare Robot for Waypoint Navigation

Finding an optimal trajectory from an initial point to a final point through closely packed obstacles, and controlling a Hilare robot through this trajectory, are challenging tasks. To serve this purpose, path planners and trajectory-tracking controllers are usually included in a control loop. This paper highlights the implementation of a trajectory-tracking controller on a stepper motor-driven Hilare robot, with a trajectory that is described as a set of waypoints. The controller was designed to handle discrete waypoints with directional discontinuity and to consider different constraints on the actuator velocity. The control parameters were tuned with the help of multi-objective particle swarm optimization to minimize the average cross-track error and average linear velocity error of the mobile robot when tracking a predefined trajectory. Experiments were conducted to control the mobile robot from a start position to a destination position along a trajectory described by the waypoints. Experimental results for tracking the trajectory generated by a path planner and the trajectory specified by a user are also demonstrated. Experiments conducted on the mobile robot validate the effectiveness of the proposed strategy for tracking different types of trajectories.

Dubins Waypoint Navigation of Small-Class Unmanned Aerial Vehicles

This paper considers a variation on the Dubins path problem and proposes an improved waypoint navigation (WN) algorithm called Dubins waypoint navigation (DWN). Based on the Dubins path problem, an algorithm is developed that is updated in real-time with a horizon of three waypoints. The purpose of DWN is to overcome a problem that we find in existing WN for small-class fixed-wing unmanned aerial vehicles (UAV) of not accurately reaching waypoints. This problem results at times in high overshoot and, in the presence of wind disturbances, it can cause a vehicle to miss the waypoint and swirl around it. To prevent this, the DWN creates “new waypoints” that are in the background, called turning points. Examples illustrate the improvement of the performance of WN achieved using the DWN algorithm in terms of the targeting of waypoints while reducing fuel and time.

Path planning method for controlling multi-UAVs to reach multi-waypoints simultaneously under the view of visual navigation

Abstract： There is a high demand for unmanned aerial vehicle （UAV） flight stability when using vi- sion as a detection method for navigation control. To meet such demand, a new path planning meth- od for controlling multi-UAVs is studied to reach multi-waypoints simultaneously under the view of visual navigation technology. A model based on the stable-shortest pythagorean-hodograph （PH） curve is established, which could not only satisfy the demands of visual navigation and control law, but also be easy to compute. Based on the model, a planning algorithm to guide multi-UAVs to reach multi-waypoints at the same time without collisions is developed. The simulation results show that the paths have shorter distance and smaller curvature than traditional methods, which could help to avoid collisions.

结合地理信息与AIS数据的海上航道自适应提取方法

海上航道对于海上态势感知具有重要意义。然而,现有的航道提取方法存在航道航路点易丢失、提取准确性不高等问题,本文依据船舶航路点数量与其途经岛屿、港口等地理区域数量相等的准则,提出了一种结合地理信息与自动识别系统(Automatic Identification System, AIS)数据的海上航道自适应提取方法。首先,构建港口之间往返船只AIS航迹数据集,将每条AIS航迹等间距分段并计算每段航迹的平均航速,设置航速差初始阈值,计算相邻航段平均航速差超过阈值的数量作为初始船只转弯次数。其次,统计AIS航迹途经岛屿、港口等地理区域的数量,若其与利用AIS航迹提取的船舶转弯次数不相等,则根据两者的差异自适应调整航速差阈值,重新提取船舶航路点,直至其与途经地理区域的数量相等,将平均航速差超出最终阈值的航迹段的连接点作为船舶航路点。然后,利用基于密度的聚类算法将所有船舶的航路点聚类为航路点集合,计算航路点集合的质心作为航道的航路点。最后,以航道航路点为顶点、航路点之间的连线为边构建有向图,并删除落在陆地上的连线后得到最终的航道提取结果。利用潍坊港—连云港港之间行驶的20条船舶的AIS数据开展了海上航道提取实验,结果表明,与基于交通路径异常检测的航道提取方法相比,本文方法得到的船舶航路点的平均虚检率降低了9.1%,平均漏检率降低了16.7%,显著提升了航道航路点位置提取的准确性。

考虑风向概率特征的航班时刻优化方法

在航班时刻表进行实际运行过程中,风向的变化对航班到达终端区共用航路点的时间造成影响,进而造成航路点的容量过载或容量浪费。因此,根据风向的统计概率对航班时刻进行调整,目的是制定在一定程度上能减少共用航路点的容量过载或容量浪费的航班时刻表。根据风向对离场航班跑道分配的影响提出基准风向的概念,并基于航季中各月份在过去5年间的机场基准风向概率预测了下一年各月的机场基准风向概率,并根据各月的基准风向概率特征进行聚类。在聚类结果的基础上,以风向变化对航路点流量的影响程度为目标函数,建立考虑风向概率特征的航班时刻优化模型,并将ε-约束法与改进粒子群优化算法(particle swarm optimization, PSO)结合提出ε-约束(ε-constraint method)-PSO组合算法实现多目标模型的求解,以北京终端区的离场航班为研究对象进行验证。结果表明:相比初始航班时刻表,共用航路点小时流量的最大值减少了12%,在不同基准风向时的共用航路点流量方差分别降低49%和56%;相比线性加权求和的方法,该方法可以实现共用航路点的溢出航班总量减少70%。结果表明:在考虑风向概率特征的条件下,该模型可以在一定程度上使共用航路点的流量更均衡,减少出现共用航路点容量过载或容量浪费的现象,减轻航路点流量受风向影响的程度。

巨型LEO星座的时不变拓扑与航点路由设计

LEO卫星网是6G空地一体通信的重要组成部分,在带来低成本广覆盖等应用优势的同时,面临高动态和快切换等技术挑战。虽然卫星规律运动,星座图时变性也有章可循,但天基网的规模远高于地面网,不能简单延用因特网现有路由技术。综合应用快照变换和虚拟节点法,以卫星及星际链路为参考系,通过3步位置变换和极区收缩处理,得到巨型LEO星座的时不变拓扑,证明完全格网的适用性,并应用航点路由机制设计了本地卫星固定式路由算法,进一步给出了格网星座与循环图的同构性以及结构优化的探索方向。

Parasitic Robot System for Waypoint Navigation of Turtle

In research on small mobile robots and biomimetic robots, locomotion ability remains a major issue despite many advances in technology. However, evolution has led to there being many real animals capable of exceUent locomotion. This paper presents a ＂parasitic robot system＂ whereby locomotion abilities of an animal are applied to a robot task. We chose a turtle as our first host animal and designed a parasitic robot that can perform ＂operant conditioning＂. The parasitic robot, which is attached to the turtle, can induce object-tracking behavior of the turtle toward a Light Emitting Diode （LED） and positively reinforce the behavior through repeated stimulus-response interaction. After training sessions over five weeks, the robot could successfully control the direction of movement of the trained turtles in the waypoint navigation task. This hybrid animal-robot interaction system could provide an alternative solution to some of the limitations of conventional mobile robot systems in various fields, and could also act as a useful interaction system for the behavioral sciences.

基于模型预测控制的固定翼无人机航迹优化研究

文章对于设计的类巡飞弹小翼展固定翼无人机,基于气动分析得到动力学参数,在设定的基准运动点附近建立线性时不变状态空间方程。对于该小扰动系统,在含约束的模型预测算法的基础上结合目标导引算法,引入航迹优化因子k1、k2,通过调节目标向量xd进而得到不同跟踪策略下的最优仿真路径。

变电站巡检无人机分层运动规划方法研究

为提升无人机变电站巡检作业的效率与质量,提出一种基于前端路径搜索和后端轨迹生成的巡检无人机分层运动规划方法。前端基于改进A^(*)算法进行路径规划,通过改进启发函数和约束节点扩展方向,提高规划速度和减少路径转弯。后端提出一种结合路径点筛选的snap最小化轨迹优化方法,生成有利于无人机巡检跟踪的平滑轨迹。仿真试验结果表明,改进的前端路径规划方法能够更快地获得转弯更少的飞行路径,结合关键点筛选的后端轨迹优化能够生成时间更短的飞行轨迹。跟踪后端优化轨迹可以获得比路径跟踪更高的跟踪精度,有利于保障无人机在巡检过程中的飞行安全与飞行稳定。

ILSM:Incorporated Lightweight Security Model for Improving QOS in WSN

In the network field,Wireless Sensor Networks(WSN)contain prolonged attention due to afresh augmentations.Industries like health care,traffic,defense,and many more systems espoused the WSN.These networks contain tiny sensor nodes containing embedded processors,TinyOS,memory,and power source.Sensor nodes are responsible for forwarding the data packets.To manage all these components,there is a need to select appropriate parameters which control the quality of service of WSN.Multiple sensor nodes are involved in transmitting vital information,and there is a need for secure and efficient routing to reach the quality of service.But due to the high cost of the network,WSN components have limited resources to manage the network.There is a need to design a lightweight solution that ensures the quality of service in WSN.In this given manner,this study provides the quality of services in a wireless sensor network with a security mechanism.An incorporated hybrid lightweight security model is designed in which random waypoint mobility(RWM)model and grey wolf optimization(GWO)is used to enhance service quality and maintain security with efficient routing.MATLAB version 16 andNetwork Stimulator 2.35(NS2.35)are used in this research to evaluate the results.The overall cost factor is reduced at 60%without the optimization technique and 90.90%reduced by using the optimization technique,which is assessed by calculating the signal-to-noise ratio,overall energy nodes,and communication overhead.

低轨卫星网络的航点分段路由及业务性能分析

提出一种基于卫星航点的分段路由(waypoint-segment routing,WSR)算法,WSR算法以可预测的卫星网络拓扑运动周期为基础,根据卫星节点链路状态确定卫星航点的位置;利用分段路由灵活规划分组传输路径的机制,提前响应网络拓扑变化,计算得到一条不受网络拓扑快照切换影响的传输路径。基于NS-3仿真平台进行仿真实验,设置源节点与目标节点在反向缝同侧与不同侧两种场景,选取优化链路状态路由(optimized link state routing,OLSR)算法和最短路径算法与WSR进行时延抖动与分组丢失率的对比分析。实验证明WSR与OLSR相比,两种场景下最大时延抖动分别降低46 ms与126 ms,分组丢失率分别降低30%和21%,并且能够解决拓扑快照切换导致分组传输路径中断的问题。

NS-2运动场景对路由协议仿真的影响

用NS-2仿真各种路由协议性能时用到的传统运动场景发生器存在两个缺陷:运动状态不能迅速过渡到稳态,节点速度的均匀分布区间起始值只能为0。为了弥补上述缺陷,Tracy Camp研制了稳态运动场景发生器。通过仿真验证了采用该发生器可大大缩短仿真时间,在此基础上仿真AODV和DSDV两种路由协议,首次从吞吐量、协议包开销、平均延迟三个方面对稳态运动场景下的两种路由协议性能进行分析,得出结论表明采用稳态运动场景进行路由协议仿真是非常必要的。

移动自组网应用建模及无线收发器选用策略

移动自组网作为一种特殊的无线网络被越来越广泛的应用,随之也变得越来越复杂.所以不同的应用场景需要采用不同的配置来组建自组网,才能达到网络性能相对最优.其中网络连通性和能源问题成为重点需要考虑的因素.为了更加合理高效地组建自组网,本文定义了一种移动自组网应用模型,并采用此模型对自组网应用场景进行了分类,提出了一种组建自组网的方法,重点对无线收发器的选择进行了研究.

基于航路点搜索法的军用飞行器航路规划

为提高军用飞行器航路规划的效率和对威胁体的适应性,提出一种基于几何原理的、步进搜索的新航路规划方法:航路点搜索法。对禁飞区、雷达和防空武器、高山等地形障碍物进行建模,推导出航路规划时的代价函数。介绍在规划空间内如何选取航路点、使用航路点搜索法在获得的航路点中进行筛选,从而生成航路的过程和原则,并根据代价函数对规划出的航路进行寻优。通过算例对航路点搜索法进行仿真验证,结果表明,该方法简单有效,收敛性好,对威胁体的类型和数量不敏感,具有一定的工程应用价值。

多约束条件下高超声速滑翔飞行器轨迹优化

研究了考虑航路点、禁飞区、热流、动压、过载、控制量以及终端状态等多种约束条件下高超声速滑翔飞行器轨迹优化设计问题。分析了采用一般Gauss伪谱方法进行高超声速滑翔飞行器轨迹优化设计存在的主要问题,为此,提出了轨迹分段优化策略,将轨迹优化的一般最优控制问题转换为多段最优控制问题,进而将各段轨迹按Gauss伪谱方法进行离散化,将连续多段最优控制问题转换为非线性规划问题进行求解。以多约束条件下最大射程轨迹优化为例进行仿真分析,结果表明分段优化方法能够较快地设计出满足各种约束条件的优化轨迹。

OruxMaps软件在卫生城市暗访及城市病媒生物防治工作中的应用

OruxMaps是安卓操作系统平台上的一款免费GPS软件。开展卫生城市暗访及城市病媒生物防治工作的现场工作人员开启OruxMaps能在OruxMaps地图上显示使用者所在地理位置,记录现场工作人员的行走线路。现场发现的问题点位可以用OruxMaps记录为带有经纬度信息的照片路点或文字路点。行走线路、路点等信息能导出为gpx或kml格式文件。电脑Global Mapper、Google地球等程序可以用于查看、分析现场获取的gpx或kml文件。电脑上保存的gpx或kml文件也能导入至安卓设备,在OruxMaps地图上显示。暗访专家用OruxMaps等软件快速获取现场信息,提升暗访工作质量。负责整改的工作人员用OruxMaps地图显示问题点位,方便在现场找到问题点位并整改。OruxMaps较适合用于监测外环境灭蚊及灭鼠。OruxMaps记录了现场监测的路径,可以用电脑计算监测路径长度及外环境蚊虫、老鼠的路径指数。为减少病媒生物监测作假行为,可以要求现场工作人员用OruxMaps记录行走线路,用照片路点记录监测状况。质量控制人员对记录的资料进行审查。由于gpx或kml文件不能造假,因此OruxMaps可以用于病媒生物监测的质量控制。

无威胁情况下任意两点间的无人机路径规划

针对无威胁情况下无人机的路径规划问题,提出了一种较简单、有效的路径规划方法:基于几何原理的无人机路径规划法。在提出了无威胁情况下路径规划的一些基本约定的基础上,重点研究了基于几何原理路径规划法的基本思想,并给出了路径规划的主要步骤。最后,通过一个仿真算例验证了此方法的有效性,并对此方法的优缺点进行了总结。