鲁棒的机器人蒙特卡洛定位算法

提出一种基于粒子滤波器的机器人定位算法. 首先利用一并行扩展卡尔曼滤波器作为粒子预测分布, 将当前观测的部分信息融入, 以改善滤波效果, 减小所需粒子数; 然后提出变密度函数边界的马尔可夫链蒙特卡洛(Markov chain Monte Carlo, MCMC)重采样方法, 以提高粒子的细化能力; 最后结合普通重采样方法, 提出一种改进的MCMC重采样的机器人定位算法, 减少粒子匮乏效应的同时, 提高了定位精度. 实验结果表明, 该算法较传统方法在计算复杂度、定位精度和鲁棒性方面都有显著提高.     

Real-time appearance-based Monte Carlo localization

A new technique for vision processing is presented which lets a mobile robot equipped with an omnidirectional camera perform appearance-based global localization in real time. The technique is applied directly to the omnidirectional camera images, producing low-dimensional rotation invariant feature vectors without any training or set-up phase. Using the feature vectors, particle filters can accurately estimate the location of a continuously moving real robot, processing 5000 simultaneous localization hypotheses on-line. Estimated body positions overlap the actual ones in over 95% of the time steps. The feature vectors show a graceful degradation against increasing levels of simulated noise and occlusion.     

The Reverse Monte Carlo localization algorithm

Global localization is a very fundamental and challenging problem in Robotic Soccer. Here, the main aim is to find the best method which is very robust and fast and requires less computational resources and memory compared to similar approaches and is precise enough for robot soccer games and technical challenges. In this work, the Reverse Monte Carlo localization (R-MCL) method is introduced. The algorithm is designed for fast, precise and robust global localization of autonomous robots in the robotic soccer domain, to overcome the uncertainties in the sensors, environment and the motion model. R-MCL is a hybrid method based on Markov localization (ML) and Monte Carlo localization (MCL), where the ML based module finds the region where the robot should be and the MCL based part predicts the geometrical location with high precision by selecting samples in this region. It is called Reverse since the MCL routine is applied in a reverse manner in this algorithm. In this work, this method is tested on a challenging data set that is used by many other researchers and compared in terms of error rate against different levels of noise, and sparsity. Additionally, the time required to recover from kidnapping and the processing time of the methods are tested and compared. According to the test results R-MCL is a considerable method against high sparsity and noise. It is preferable when its recovery from kidnapping and processing times are considered. It gives robust and fast but relatively coarse position estimations against imprecise and inadequate perceptions, and coarse action data, including regular misplacements, and false perceptions.     

Efficient and reliable Monte Carlo localization with thinning edges

The global convergence of MCL is time-consuming because of a large number of random samples. Moreover, its success is not guaranteed at all times. This paper presents a novel approach to reduce the number of samples of MCL and one heuristic approach to detect localization failure using thinning edges extracted in real time. Random samples are drawn only around the neighborhood of the thinning edges rather than over the entire free space and localization quality is estimated through the probabilistic analysis of samples added around the thinning edges. A series of experiments verified the performance of the proposed scheme.     

Reliable Monte Carlo localization for mobile robots

Reliability is a key factor for realizing safety guarantee of fully autonomous robot systems. In this paper, we focus on reliability in mobile robot localization. Monte Carlo localization (MCL) is widely used for mobile robot localization. However, it is still difficult to guarantee its safety because there are no methods determining reliability for MCL estimate. This paper presents a novel localization framework that enables robust localization, reliability estimation, and quick relocalization, simultaneously. The presented method can be implemented using a similar estimation manner to that of MCL. The method can increase localization robustness to environment changes by estimating known and unknown obstacles while performing localization; however, localization failure of course occurs by unanticipated errors. The method also includes a reliability estimation function that enables a robot to know whether localization has failed. Additionally, the method can seamlessly integrate a global localization method via importance sampling. Consequently, quick relocalization from a failure state can be realized while mitigating noisy influence of global localization. We conduct three types of experiments using wheeled mobile robots equipped with a two-dimensional LiDAR. Results show that reliable MCL that performs robust localization, self-failure detection, and quick failure recovery can be realized.     

On input-dependent system identification by Monte Carlo approach

The problem of a weighted least-squares approximation of a memoryless system within a given class of models is discussed, and an identification algorithm leading to the best model when only input-output data are accessible is derived using a concept of random choice of inputs.     

缩小采样区域的蒙特卡罗移动节点定位算法

针对无线传感器网络中移动节点定位问题,提出一种适用于未知节点移动而信标节点固定的改进蒙特卡罗定位算法,充分利用信标节点与未知节点间的测距误差来缩小采样区域,提高采样效率。仿真结果表明,改进算法在信标节点密度、连通度和节点最大运动速度等不同情况下均能提高定位精度,减少采样次数和计算量,延长网络的生存周期。     

不完整地图中移动机器人蒙特卡罗定位研究*

针对移动机器人在不完整地图中定位的问题,提出了一种改进的粒子聚类蒙特卡罗定位(Monte Carlo localization, MCL)算法。在定位过程中,将机器人的位姿分为六种状态,每一种状态对应一个粒子簇。在机器人运动的过程中,这六种状态之间可以相互转移,在计算状态转移概率的基础上,实现了不完整地图中移动机器人蒙特卡罗定位算法。实验验证了该算法在解决移动机器人在不完整地图中定位问题的有效性。     

冷凝管水下视觉定位系统研究

根据机器人水下工作环境和工况要求,针对冷凝管清洗设备坐标输入法定位不准的问题引入了机器视觉技术,分析了系统的可行性设计,设计了一套基于DSP的嵌入式机器视觉系统,并详细叙述了照明方式、图像采集模块、图像处理模块的组成及工作原理,最后结合系统应用要求和算法的实时性,通过最大方差法及重心法完成了管口圆心的定位。该视觉系统取得良好的实验结果,能在一定程度上提高整个机器人系统的集成度、定位的快速性与精确度。     

基于量子遗传的蒙特卡洛节点定位算法

针对无线传感器网络(WSNs)节点定位的问题,提出了一种量子遗传算法与蒙特-卡洛相结合的定位算法(QGA-MCL).将QGA应用于MCL中的采样过滤阶段,通过合理的编码方案、译码方案以及量子旋转门对采样区域中随机产生的量子染色体进行操作,提高了样本寻优效率和定位精度,并加快了算法的收敛速度.仿真结果表明:与蒙特-卡洛定位算法相比,提出的QGA-MCL算法能够减少约10.2％的定位误差,同时,算法的收敛速度也得到了显著提升.     

基于测距的蒙特卡罗盒传感网定位算法研究

针对以蒙特卡罗算法为基础的无线传感器网定位算法普遍存在定位精度和采样效率低的问题,提出了一种基于测距的蒙特卡罗盒（R-MCB）定位算法。通过测距信息构造修正的包含有约束条件的方形边界框,使用从强约束条件中除去弱约束条件的启发法来提高采样效率,然后进行样本过滤和加权处理,并通过校准减少距离误差实现精确的定位。该R-MCB定位算法允许节点是静止或移动的,并且能够与可进行测距的节点和没有测距能力的节点协同工作。通过在传感器硬件上进行真实模拟定位算法证明,在多数情况下该R-MCB算法的定位误差,均要比WMCL算法（加权蒙特卡罗定位算法）的定位误差低10%左右。     

Robust particle tracker via Markov Chain Monte Carlo posterior sampling

Particle Filter has grown to be a standard framework for visual tracking. This paper proposes a robust particle tracker based on Markov Chain Monte Carlo method, aiming at solving the thorny problems in visual tracking induced by object appearance changes, occlusions, background clutter, and abrupt motions. In this algorithm, we derive the posterior probability density function based on second order Markov assumption. The posterior probability density is the joint density of the previous two states. Additionally, a Markov Chain with certain length is used to approximate the posterior density to avoid the drawbacks of traditional importance sampling based algorithm, which consequently improves the searching ability of the proposed tracker. We compare our approach with several alternative tracking algorithms, and the experimental results demonstrate that our tracker is superior to others in dealing with various types of challenging scenarios.     

KLD sampling with Gmapping proposal for Monte Carlo localization of mobile robots

The paper proposes an algorithm for mobile robot navigation that integrates the Gmapping proposal distribution with the Kullback–Leibler divergence for adapting the number of particles. This results in a very effective particle filter with adaptive sample size. The algorithm has been evaluated in both simulation and experimental studies, using the standard KLD—sampling MCL as a benchmark. Simulation results show that the proposed algorithm achieves higher localization accuracy with a smaller number of particles compared to the benchmark algorithm. In a more realistic scenario using experimental data and simulated robot odometry with drift, the proposed algorithm again has greater accuracy using a lower number of particles.     

基于自适应多提议分布粒子滤波的蒙特卡洛定位算法

针对基于Cubature粒子滤波的蒙特卡罗定位（CMCL）算法存在的计算量大、实时处理能力较差的问题,提出一种基于自适应多提议分布粒子滤波的蒙特卡罗定位（AMPD-MCL）算法。该算法利用Cubature卡尔曼滤波和扩展卡尔曼滤波改进提议分布,融入当前观测信息,减弱粒子退化现象;重采样部分采用Kullback-Leibler距离（KLD）采样,根据粒子在状态空间的分布状况,在线调整下一次滤波迭代所需粒子数,从而减小计算量。仿真实验验证了自适应多提议分布粒子滤波（AMPD-PF）的有效性;同时在机器人操作系统（ROS）上进行实验,结果表明改进算法的平均定位精度达到19.891cm,定位所需粒子数稳定在60,定位时间为45.543s,较CMCL算法在定位精度上提高了71.03%,时间缩短了63.10%。实验结果表明,AMPD-MCL算法减小了定位误差,能实时在线调整粒子数,有效减少了算法计算量,提高了实时处理能力。     

Accelerating Monte Carlo simulations with an NVIDIA graphics processor

Modern graphics cards, commonly used in desktop computers, have evolved beyond a simple interface between processor and display to incorporate sophisticated calculation engines that can be applied to general purpose computing. The Monte Carlo algorithm for modelling photon transport in turbid media has been implemented on an NVIDIA^® 8800gt graphics card using the CUDA toolkit. The Monte Carlo method relies on following the trajectory of millions of photons through the sample, often taking hours or days to complete. The graphics-processor implementation, processing roughly 110 million scattering events per second, was found to run more than 70 times faster than a similar, single-threaded implementation on a 2.67 GHz desktop computer.

Program summary

Program title: Phoogle-C/Phoogle-GCatalogue identifier: AEEB_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEEB_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 51 264No. of bytes in distributed program, including test data, etc.: 2 238 805Distribution format: tar.gzProgramming language: C++Computer: Designed for Intel PCs. Phoogle-G requires a NVIDIA graphics card with support for CUDA 1.1Operating system: Windows XPHas the code been vectorised or parallelized?: Phoogle-G is written for SIMD architecturesRAM: 1 GBClassification: 21.1External routines: Charles Karney Random number library. Microsoft Foundation Class library. NVIDA CUDA library [1].Nature of problem: The Monte Carlo technique is an effective algorithm for exploring the propagation of light in turbid media. However, accurate results require tracing the path of many photons within the media. The independence of photons naturally lends the Monte Carlo technique to implementation on parallel architectures. Generally, parallel computing can be expensive, but recent advances in consumer grade graphics cards have opened the possibility of high-performance desktop parallel-computing.Solution method: In this pair of programmes we have implemented the Monte Carlo algorithm described by Prahl et al. [2] for photon transport in infinite scattering media to compare the performance of two readily accessible architectures: a standard desktop PC and a consumer grade graphics card from NVIDIA.Restrictions: The graphics card implementation uses single precision floating point numbers for all calculations. Only photon transport from an isotropic point-source is supported. The graphics-card version has no user interface. The simulation parameters must be set in the source code. The desktop version has a simple user interface; however some properties can only be accessed through an ActiveX client (such as Matlab).Additional comments: The random number library used has a LGPL (http://www.gnu.org/copyleft/lesser.html) licence.Running time: Runtime can range from minutes to months depending on the number of photons simulated and the optical properties of the medium.References:

[1]

http://www.nvidia.com/object/cuda_home.html.

[2]

S. Prahl, M. Keijzer, Sl. Jacques, A. Welch, SPIE Institute Series 5 (1989) 102.

     

基于多假设粒子群优化的蒙特卡罗定位算法

针对传统蒙特卡罗定位(MCL)算法在结构化相似环境中容易出现定位失败的问题,提出一种基于多假设粒子群优化的改进蒙特卡罗定位方法(MPSO-CL).以激光传感器的观测信息作为适应度函数,对MCL算法的采样粒子进行多假设粒子群优化更新,使得采样粒子向当前群体中多个最优粒子方向移动,从而使得粒子迅速收敛到后验概率密度分布取值较大的区域,实现了移动机器人高效精确自主定位.实验结果表明,MPSO-MCL算法克服了相似环境中定位的粒子匮乏问题,并且提高了定位的精确度.     

General and Robust Error Estimation and Reconstruction for Monte Carlo Rendering

Adaptive filtering techniques have proven successful in handling non‐uniform noise in Monte‐Carlo rendering approaches. A recent trend is to choose an optimal filter per pixel from a selection of non spatially‐varying filters. Nonetheless, the best filter choice is difficult to predict in the absence of a reference rendering. Our approach relies on the observation that the reconstruction error is locally smooth for a given filter. Hence, we propose to construct a dense error prediction from a small set of sparse but robust estimates. The filter selection is then formulated as a non‐local optimization problem, which we solve via graph cuts, to avoid visual artifacts due to inconsistent filter choices. Our approach does not impose any restrictions on the used filters, outperforms previous state‐of‐the‐art techniques and provides an extensible framework for future reconstruction techniques.