嵌入式移动机器人红外路标定位模块研究

针对室内环境移动机器人的自定位问题,提出一种嵌入式移动机器人红外路标定位模块。采用基于单应矩阵的初始标定算法和陒机初始标定方法,补偿由于实际使用中的安装误差所引起的定位偏差。实验结果表明,该模块易于嵌入式系统实现,定位模块位置精度可达厘米级别,角度定位精度雓于6°。     

Camera Recognition and Laser Detection based on EKF-SLAM in the Autonomous Navigation of Humanoid Robot

The ability of autonomous navigation of the humanoid robot under unknown environment is very important to real-life applications. EKF-SLAM based on the camera recognition and laser detection for humanoid robot NAO is presented in this paper. Camera recognition is used to recognize if the object is a landmark. Because the computational resources needed for the feature-based position estimation are quite expensive, the laser instead of the camera provides the position of the landmark. A fractional order proportional-integral (PI) controller is designed to reduce the derivation of the NAO robot from the desired path during autonomous navigation. Experiments show that the proposed method is valid and reliable for autonomous navigation of the NAO robot under unknown environment.     

室内移动机器人的视觉定位方法研究

针对地图未知的室内环境下的定位问题,提出了一种基于特征跟踪的视觉里程计方法．利用单目摄像头提取和跟踪环境特征点集,进而根据观测模型利用扩展卡尔曼滤波算法估算出机器人的位姿．办公室环境中的定位实验证明了方法的有效性．     

Multirobot Localization in Highly Symmetrical Environments

The paper addresses and solves the problem of multirobot collaborative localization in highly symmetrical 2D environments, such as the ones encountered in logistic applications. Because of the environment symmetry, the most common localization algorithms may fail to provide a correct estimate of the position and orientation of the robot, if its initial position is not known, no specific landmark is introduced, and no absolute information (e.g., GPS) is available: the robot can estimate its position with respect to the walls of the corridor, but it could be critical to determine in which corridor it is actually moving. The proposed algorithm is based upon a particle filter cooperative Monte Carlo Localization (MCL) and implements a three-stage procedure for the global localization and the accurate position tracking of each robot of the team. Online simulations and experimental tests, which investigate different situations with respect to the number of robots involved and their initial positions, show how the proposed solution can lead to the global localization of each robot, with a precision sufficient to be used as starting point for the subsequent robot tracking.     

A Modified Particle Filter for Simultaneous Localization and Mapping

The implementation of a particle filter (PF) for vision-based bearing-only simultaneous localization and mapping (SLAM) of a mobile robot in an unstructured indoor environment is presented in this paper. Variations, using techniques from the genetic algorithm (GA), to standard PF procedures are proposed to alleviate the sample impoverishment problem. A monochrome CCD camera mounted on the robot is used as the measuring device and a measure on the image quality is incorporated into data association and PF update. Since the bearing-only measurement does not contain range information, we add a pseudo range to the measurement during landmark initialization as a hypothesised pair and the non-promising landmark is removed by a map management strategy. Simulation and experimental results from an implementation using real-life data acquired from a Pioneer robot are included to demonstrate the effectiveness of our approach.     

基于全景近红外视觉的室外移动机器人定位系统

针对室外移动机器人定位、导航问题,提出了一种基于全景近红外视觉的路标定位系统。系统通过近红外主动照明降低了光照变化、阴影等因素的影响,利用全景摄像机获得大范围的路标定向信息。图像处理中改进大津法和路标跟踪的应用使识别路标更准确、更快速,三角定位算法确保能精确的计算出机器人的世界坐标。室外环境下移动机器人的定位实验结果表明,本系统具有较高的定位精度和良好的鲁棒性。     

基于目标跟踪的并联机器人视觉位姿检测

建立一种基于视觉的并联机器人位姿检测系统框架,包括图像采集、图像处理、位姿检测、参数反馈4个部分。使用单目摄像头采集图像,以二自由度冗余机器人为控制对象,利用Haar特征提取对目标进行粗跟踪。进一步获得目标上特定的几个特征点,基于平行不变性原理,得到机器人末端操作器的实际位姿参数。通过求解机器人的逆运动学方程,得到电机的控制参数。实验和仿真验证了该系统的可行性。     

Omnivision-based KLD-Monte Carlo Localization

Mobile robots operating in real and populated environments usually execute tasks that require accurate knowledge on their position. Monte Carlo Localization (MCL) algorithms have been successfully applied for laser range finders. However, vision-based approaches present several problems with occlusions, real-time operation, and environment modifications. In this article, an omnivision-based MCL algorithm that solves these drawbacks is presented. The algorithm works with a variable number of particles through the use of the Kullback–Leibler divergence (KLD). The measurement model is based on an omnidirectional camera with a fish-eye lens. This model uses a feature-based map of the environment and the feature extraction process makes it robust to occlusions and changes in the environment. Moreover, the algorithm is scalable and works in real-time. Results on tracking, global localization and kidnapped robot problem show the excellent performance of the localization system in a real environment. In addition, experiments under severe and continuous occlusions reflect the ability of the algorithm to localize the robot in crowded environments.     

一种基于灭影线的无人直升机位姿估计方法

该文将基于灭影线的摄像机标定原理用于无人直升机的位姿估计,设计了一个包含四组平行线的平面着陆图标,通过机载摄像机摄取的图标图像,估计出直升机相对于该图标的位置和姿态。文章首先简述了灭影线的有关知识,推导了相应的关系方程,接着介绍了使用的图像处理方法和提高计算精度的措施,最后,给出了实验结果并对实验误差做了简要分析。该方法的技术关键是如何精确测定灭影点和灭影线的像平面参数,算法最大的特点为计算结果与焦距变化的无关性。实验结果表明,该方法算法复杂性低,实时性好,精度较高,可以用于无人直升机的位姿估计。     

基于视觉的机器人定位精度提高方法

定位是确定机器人在其工作环境中所处位置的过程,精确、可靠地实现定位是移动机器人应该具备的一项最基本也是最重要的功能之一。针对机器人在完成穿过门的导航任务过程中,现有的视觉定位方法存在精度不高,不能为机器人的导航提供精确位置信息的问题,提出了一种基于离线学习的方法来得到摄像机的内部参数随机器人位置的变化关系,使机器人在粗定位的基础上,自适应地调节摄像头的内部参数,修正定位结果,达到提高定位精度的目的。实验证明了该方法的有效性。     

Artificial landmark-based underwater localization for AUVs using weighted template matching

This paper deals with vision-based localization techniques in structured underwater environments. For underwater robots, accurate localization is necessary to perform complex missions successfully, but few sensors are available for accurate localization in the underwater environment. Among the available sensors, cameras are very useful for performing short-range tasks despite harsh underwater conditions including low visibility, noise, and large areas of featureless scene. To mitigate these problems, we design artificial landmarks to be utilized with a camera for localization, and propose a novel vision-based object detection technique and apply it to the Monte Carlo localization (MCL) algorithm, a map-based localization technique. In the image processing step, a novel correlation coefficient using a weighted sum, multiple-template-based object selection, and color-based image segmentation methods are proposed to improve the conventional approach. In the localization step, to apply the landmark detection results to MCL, dead-reckoning information and landmark detection results are used for prediction and update phases, respectively. The performance of the proposed technique is evaluated by experiments with an underwater robot platform and the results are discussed.     

采用磁传感器的餐厅服务机器人导引控制方法

针对餐厅环境复杂、定位精度低等问题,提出了一种以磁传感器为核心的餐厅服务机器人导引控制方法。该方法通过安装在机器人底盘的磁传感器感知铺设在地面下的磁条,使得机器人能够平滑、准确地沿着磁条运动,在运动的过程中,结合地标模块感知到的地标信息,获取精准的位置信息和工作状态。最后将该方法应用于一种实际餐厅服务机器人,实现了机器人在餐厅内的精准定位与导航。实验结果表明,本文所提方法性能可靠、成本较低、实用性较强,具有较广阔的应用前景。     

一种新型的并联机器人位姿立体视觉检测系统

建立了一种并联机器人位姿立体视觉测量系统框架,主要包括图像采集与传输、摄像机标定、尺度不变量特征变换（SIFT）匹配、空间点重建和位姿测量五个部分。该系统基于SIFT,能够很好地处理图像在大视角有遮挡、平移、旋转、亮度和尺度变化时的特征点匹配,有较高的匹配精度,特别适用于对并联机器人多自由度和空间复杂运动的检测。最后使用该方法对并联机器人位姿检测做了仿真实验。     

一种基于视觉的图书馆室内定位方法

提出一种可用于图书馆内图书运载车的车辆室内自动定位定向方法。借鉴二维条形码思想,设计了一种简单方便、易于识别、内含绝对位置坐标、具有一定纠错能力的路标,可将路标放置在图书馆天花板上,由安装于图书运载车上且光轴和天花板垂直的摄像机进行拍摄。通过图像分割、连通域寻找、轮廓特征曲线匹配以及路标特征识别步骤定位路标,解析路标中所包含的坐标信息以及偏转角度,进而计算出车辆当前所处的绝对位置和航向角。通过实验,验证了所提出方法的有效性,能够满足图书馆内图书运载车室内定位的要求。     

Selecting Landmarks for Localization in Natural Terrain

We describe techniques to optimally select landmarks for performing mobile robot localization by matching terrain maps. The method is based upon a maximum-likelihood robot localization algorithm that efficiently searches the space of possible robot positions. We use a sensor error model to estimate a probability distribution over the terrain expected to be seen from the current robot position. The estimated distribution is compared to a previously generated map of the terrain and the optimal landmark is selected by minimizing the predicted uncertainty in the localization. This approach has been applied to the generation of a sensor uncertainty field that can be used to plan a robot's movements. Experiments indicate that landmark selection improves not only the localization uncertainty, but also the likelihood of success. Examples of landmark selection are given using real and synthetic data.     

Robot docking based on omnidirectional vision and reinforcement learning

We present a system for visual robotic docking using an omnidirectional camera coupled with the actor critic reinforcement learning algorithm. The system enables a PeopleBot robot to locate and approach a table so that it can pick an object from it using the pan-tilt camera mounted on the robot. We use a staged approach to solve this problem as there are distinct subtasks and different sensors used. Starting with random wandering of the robot until the table is located via a landmark, then a network trained via reinforcement allows the robot to turn to and approach the table. Once at the table the robot is to pick the object from it. We argue that our approach has a lot of potential allowing the learning of robot control for navigation and remove the need for internal maps of the environment. This is achieved by allowing the robot to learn couplings between motor actions and the position of a landmark.     

基于视觉伺服的输电线巡检机器人抓线控制

巡检机器人在自动越障时,需要完成机器人手臂的准确抓线控制。结合输电线的几何特征和摄像机成像原理,提出了一种基于单摄像机的立体视觉方法来确定输电线的位置和姿态。结合该定位方法及视觉伺服理论建立机械手抓线伺服控制模型。在自行研制的巡检机器人进行了视觉伺服抓线实验。实验结果验证了该方法的有效性。     

Multi-view facial landmark detection by using a 3D shape model

An algorithm for accurate localization of facial landmarks coupled with a head pose estimation from a single monocular image is proposed. The algorithm is formulated as an optimization problem where the sum of individual landmark scoring functions is maximized with respect to the camera pose by fitting a parametric 3D shape model. The landmark scoring functions are trained by a structured output SVM classifier that takes a distance to the true landmark position into account when learning. The optimization criterion is non-convex and we propose a robust initialization scheme which employs a global method to detect a raw but reliable initial landmark position. Self-occlusions causing landmarks invisibility are handled explicitly by excluding the corresponding contributions from the data term. This allows the algorithm to operate correctly for a large range of viewing angles. Experiments on standard “in-the-wild” datasets demonstrate that the proposed algorithm outperforms several state-of-the-art landmark detectors especially for non-frontal face images. The algorithm achieves the average relative landmark localization error below 10% of the interocular distance in 98.3% of the 300 W dataset test images.