共查询到20条相似文献,搜索用时 15 毫秒
1.
In this paper, we consider the deferred correction principle for initial boundary value problems. The method will here be applied to the discretization in time. We obtain a method of even order p by applying the implicit midpoint rule p/2 times in each time step. For the space discretization we will use a compact implicit difference scheme. We derive error estimates for the case of time dependent coefficients and present numerical experiments confirming the theoretical analysis. 相似文献
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卫星自主定轨时选择测量卫星的几何构型对于定轨精度有着重要的影响.目前地面接收机与导航卫星的几何构型对定位精度的影响主要由GDOP(几何衰减因子)来衡量,GDOP值的下限限制了在一定的测量精度下用户定位的精度范围.通过构建Walker构型的导航星座将地面接收机GDOP取最小值时的边界确定,推广应用到自主导航环境下,利用均匀采样和遗传算法分别独立得到GDOP的最小值,同时用仿真数据验证了这个值的正确性. 相似文献
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Mars Rover Autonomous Navigation 总被引:5,自引:0,他引:5
M. Maurette 《Autonomous Robots》2003,14(2-3):199-208
Autonomous navigation of a rover on Mars surface can improve very significantly the daily traverse, particularly when driving away from the lander, into unknown areas. The autonomous navigation process developed at CNES is based on stereo cameras perception, used to build a model of the environment and generate trajectories. Multiple perception merging with propagation of the locomotion and localization errors have been implemented. The algorithms developed for Mars exploration programs, the vision hardware, the validation tools, experimental platforms and results of evaluation are presented. Portability and the evaluation of computing resources for implementation on a Mars rover are also addressed. The results show that the implementation of autonomy requires only a very small amount of energy and computing time and that the rover capabilities are fully used, allowing a much longer daily traverse than what is enabled by purely ground-planned strategies. 相似文献
4.
This paper considers a family of spatially discrete approximations, including boundary treatment, to initial boundary value
problems in evolving bounded domains. The presented method is based on the Cartesian grid embedded Finite-Difference method,
which was initially introduced by Abarbanel and Ditkowski (ICASE Report No. 96-8, 1996; and J. Comput. Phys. 133(2), 1997) and Ditkowski (Ph.D. thesis, Tel Aviv University, 1997), for initial boundary value problems on constant irregular domains.
We perform a comprehensive theoretical analysis of the numerical issues, which arise when dealing with domains, whose boundaries
evolve smoothly in the spatial domain as a function of time. In this class of problems the moving boundaries are impenetrable
with either Dirichlet or Neumann boundary conditions, and should not be confused with the class of moving interface problems
such as multiple phase flow, solidification, and the Stefan problem.
Unlike other similar works on this class of problems, the resulting method is not restricted to domains of up to 3-D, can
achieve higher than 2nd-order accuracy both in time and space, and is strictly stable in semi-discrete settings. The strict
stability property of the method also implies, that the numerical solution remains consistent and valid for a long integration
time.
A complete convergence analysis is carried in semi-discrete settings, including a detailed analysis for the implementation
of the diffusion equation. Numerical solutions of the diffusion equation, using the method for a 2nd and a 4th-order of accuracy
are carried out in one dimension and two dimensions respectively, which demonstrates the efficacy of the method.
This research was supported by the Israel Science Foundation (grant No. 1362/04). 相似文献
5.
邱广萍 《数字社区&智能家居》2014,(3):1586-1588,1617
从硬件电路设计和软件设计两大方面入手,分析基于激光传感器的智能车自主导航系统的设计过程。通过分析基于激光传感器芯片制作的自主导航智能车的设计原理和方案,从机械结构设计,硬件电路设计,程序算法设计以及调试经验等四个方面全面介绍智能车的制作及调试过程。经过实验对比和竞赛,表明测速模块、电机驱动模块及激光传感器的设计和选择,软件程序的编写和算法的选择有效地实现了智能车的高速自主导航。 相似文献
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利用献[1]的献[2]中的“solution-matching”方法探讨了n阶常微分方程三点边值问题解的存在性和唯一性,推广了献[1]和献[2]中的结果。 相似文献
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由于林荫道中阴影的影响,目前常用的基于被动式传感器技术的视觉导航方法(如采用图像的方法),难以取得比较理想的结果。对于这种环境,主动式传感器具有一定的优势,文中采用了激光雷达传感器。首先利用传感器对路边的树木等物体作为障碍物来进行检测,并据此信息来推算道路边界,详细介绍了具体的方案和算法。实验结果表明,所设计的方法具有很好的鲁棒性,可以满足实际导航的需要。 相似文献
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基于SCADE的无人机自主导航飞行软件设计 总被引:1,自引:0,他引:1
该文研究了一种无人机飞行控制软件设计方法,利用高安全性的应用程序开发环境-SCADE(Safety-Critical Application Development Environment)开发无人机自主导航功能模块的软件;按照SCADE开发嵌入式软件设计流程,自动生成可直接面向工程的高安全性嵌入式代码;并通过代码的效率测试和安全性测试,验证了在SCADE环境下进行无人机软件开发的优越性;由此得出SCADE很大程度上实现了软件开发的自动化,节约了开发成本和开发时间,并具有很高的安全性特征. 相似文献
11.
跟随路径导引是自主式移动机器人广泛采用的一种导航方式,其中视觉导航具有其他传感器导航方式所无法比拟的优点,是移动机器人智能导航的主要发展方向。为了提高移动机器人视觉导航的实时性和准确性,提出了一个基于路径识别的视觉导航系统,其基本思想是首先用基于变分辨率的采样二值化和形态学去噪方法从原始场景图像中提取出目标支持点集,然后用一种改进的哈夫变化检测出场景中的路径,最后由路径跟踪模块分直行和转弯两种情况进行导航计算。实验结果表明,该视觉导航系统具有较好的实时性和准确性。 相似文献
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Due to the requirements for mobile robots to search or rescue in unknown environments,reactive navigation which plays an essential role in these applications has attracted increasing interest.However,most existing reactive methods are vulnerable to local minima in the absence of prior knowledge about the environment.This paper aims to address the local minimum problem by employing the proposed boundary gap(BG)based reactive navigation method.Specifically,the narrowest gap extraction algorithm(NGEA)is proposed to eliminate the improper gaps.Meanwhile,we present a new concept called boundary gap which enables the robot to follow the obstacle boundary and then get rid of local minima.Moreover,in order to enhance the smoothness of generated trajectories,we take the robot dynamics into consideration by using the modified dynamic window approach(DWA).Simulation and experimental results show the superiority of our method in avoiding local minima and improving the smoothness. 相似文献
13.
基于虚拟子目标的移动机器人主动寻径导航 总被引:2,自引:0,他引:2
纯粹的反应式导航算法有时会出现“没有远见现象”,为此设计了一种基于行为和虚拟路径子目标的
移动机器人主动寻径导航策略.该策略首先在机器人的局部探测域内运用改进的可视点寻径法寻找最优虚拟子目
标,接着使用行为决策树实现快速的行为决策.机器人将如人类寻路一样,主动地灵巧绕过障碍物,基于圆弧轨迹
的运动方式使之能以平滑的路径到达目标.仿真结果验证了本策略的可行性和有效性. 相似文献
14.
A class of singularly perturbed two-point boundary-value problems (BVPs) for second-order ordinary differential equations (DEs) is considered here. In order to obtain numerical solution to these problems, an iterative non-overlapping domain decomposition method is suggested. The BVPs are independent in each subdomain and one can use parallel computers to solve these BVPs. One of the characteristics of the method is that the number of processors available is a free parameter of the method. Practical experiments on a Silicon Graphics Origin 200, with 4 MIPS R10000 processors have been performed, showing the reliability and performance of the proposed parallel schemes. Error estimates for the solution and numerical examples are provided. 相似文献
15.
为高效、低成本地实现无线传感器网络(WSN)移动节点自主导航,提出了一种利用节点间接收信号
强度信息(RSSI)和网络拓扑结构实现移动节点自主导航的方法,由多个信标节点组成一个分布式导航子网络,每
个节点都有其相对独立的导航目标并会做出有利于自己的决策,采用多目标群体决策协调技术融合多个节点决策信
息以获得机器人最终导航控制策略,使整个导航系统达到最优控制.导航算法采用分布式处理技术,使绝大部分数
据处理任务都由各个信标节点分布执行,因此很大程度上简化了机器人的设计和硬件成本.仿真和现场实验都表明
了该系统的有效性. 相似文献
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三维场景的虚拟导航需要同时保证相机视角的光滑性和智能性,在算法设计上极具挑战。文章研发了一套实时自动生成光滑连续且高效的相机路径导航系统。首先通过线下模型几何分析和语义分析,包含分析场景中建筑物模型、道路模型以及非建筑的重要模型等,求得模型重要性值;其次是自适应地获取路线采样点以及高效存储采样点的视角图片;最后是利用动态规划的方式求出每个采样点的最佳视角并光滑地连接这些采样点形成相机运行轨迹。4 个不同三维场景的实验结果表明了所提算法的高效性和智能性,同时文章所进行的用户调查也充分反映了所提方法具有的明显优势。 相似文献
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把具有不同重要性的功能集成到一个共享平台上的混合关键级系统,是当前嵌入式系统发展的主要趋势之一.已有的混合关键级调度理论为了保证高关键级作业的完成,大多不支持关键级向下切换,在系统进入高关键级后直接放弃低关键级作业的执行,这对系统中作业集的整体完成率有负面影响.为了应对这一问题,把需求边界分析理论扩展到混合关键级作业系统中,提出了作业的动态需求边界函数,以矢量的形式记录系统在运行时需求边界函数的动态变化,并相应地提出了作业的混合关键级松弛时间与系统关键级松弛时间的概念.在此基础上,提出了一种基于动态需求边界的混合关键级作业调度算法CSDDB(criticality switch based on dynamical demand boundary).该算法选择具有最小松弛时间的关键级作为执行关键级,在保证高关键级作业可调度的情况下,充分利用系统资源,尽可能地满足低关键级作业的执行.应用随机生成的任务集进行仿真实验,结果表明,与已有算法相比,CSDDB在系统关键级的保证与作业集整体完成率方面比现有算法有10%以上的提升. 相似文献