一种环状编码标记点的设计及解码算法

针对近景摄影测量中对编码标志点的精确定位和准确识别的要求,提出一种环状编码标记点的设计和识别算法。在传统环状编码标记点的基础上添加3个定位符,用于确定标志点的精确位置和增加标志点的数量。解码时先检测定位符坐标及其在标志点中的位置,然后对编码标志点进行透视变换以实现图像校正的目的,最后用提出的基于圆环扫描的方法进行解码。实验结果表明,该算法对任意旋转角度下的编码标志点均能有较好的检测识别效果;当摄像机与标记平面的夹角小于65°时,其识别准确率可达99.3%;在复杂背景情况下的平均识别准确率为97.4%,误识别率为1.25%,识别平均速率为2.15 s/幅。     

基于线结构光的三维坐标测量技术研究

传统的口腔修复体三维点云数据测量技术难以满足精度要求。为此,提出一种基于线结构光的三维坐标测量方法。在摄像机标定过程中,采用最小二乘法计算光平面方程,使用平移扫描和旋转扫描获取物体表面三维数据,以避免求解摄像机内外参数。实验结果表明,重建后的三维模型可以满足高精度近景三维测量的要求。     

一种基于靶标识别定位算法的视觉测量技术

视觉测量在飞行试验高精度测试中发挥着重要作用。针对常规视觉测量中多标志点识别定位存在误识别、定位精度低等问题,设计了一种新的环形编码对角标志,并提出了一种基于环形编码对角标志识别定位算法的视觉测量技术。重点介绍了基于EDCircles圆检测算法的标志点识别、基于Harries角点检测算法的亚像素级定位和基于坐标变换的编码信息解码等技术的实现。经过实验验证,研究成果编码标志点识别定位算法识别准确、鲁棒性强、定位精度高,在大投影角度下仍能达到92%的识别率,可以满足飞行试验动态视觉测量任务相关需求。     

一种圆形编码标志点的设计及解码算法研究

为提高大尺寸摄影测量中编码标志点编码容量和解码准确率,设计一种由定位圆、起始圆和编码圆组成编码标志点.解码时,按圆度和面积提取、区分各种圆;对编码标志点进行透视变换实现编码圆的位置校正;对校正后的编码标志点解码.分别在物、象平面夹角为0°,45°,60°和室外复杂场景进行了实验,解码准确率均可达到100％.实验结果表明:编码标志点具有方便提取和识别、编码容量大、鲁棒性强等优点,为大尺寸摄影测量中数据拼接提供一种新的编码标志点.     

点阵测头成像视觉坐标测量系统的研究

柔性三维坐标测量在工业现场测量有较多应用.分析多目标点透视成像原理的基础上,提出了点阵测头成像视觉坐标测量的概念,给出系统完整的三种数学模型及求解方法.设计了一种实用测头,基于单台面阵CCD摄像机实现由三种类型测头组成的视觉测量样机.在距离摄像机1 000 mm,样机进行实际测量,并与三坐标测量机的检测结果进行比对.测试结果表明在摄像机成像面平行的两个方向的测量精度高于摄像机轴向测量精度.     

自由曲面视觉测量标志点三维匹配方法研究

提出一种适用于自由曲面视觉测量的标志点三维匹配方法.该方法首先通过编码标志点确定局部测量区域在物体上的初始位置,获得可能匹配点集;然后根据非编码标志点与编码标志点之间的距离、角度、方向等特征,获得全局坐标系与局部坐标系之间的初始转换关系;最后根据此初始转换关系求解最终匹配点集,完成标志点的三维匹配.该方法适用于基于标志...     

激光线扫式形貌测量机器人的标定研究

为能够高效、高精度的获取大型自由曲面物体的形貌,研究了基于通用工业机器人和激光线扫描传感器的测量方法。论述了激光线扫式形貌测量系统的原理与结构,利用标准球及优化算法实现了机器人和激光扫描传感器位姿关系的精确解算,并针对机器人运动学误差对系统测量影响较大,通过对机器人运动学参数的修正有效减小了机器人的绝对定位误差。实验和分析结果表明,经标定和运动学参数校正后的测量系统对标准球的测量能达到较高精度,为采集高精度三维点云提供了保证。     

姿态和表情变化下的三维人脸标志点定位

三维人脸标志点定位在人脸识别、人脸跟踪、人脸建模、表情分析等方面具有非常重要的作用. 然而, 在姿态和表情变化很大的条件下进行标志点定位, 这仍然是一个很具挑战性的课题. 本文提出一种对姿态和表情不敏感的三维人脸标志点定位方法, 利用HK曲率分析检测出候选标志点, 根据对面部形状的先验知识, 提出一种基于人脸几何结构的分类策略对候选标志点进一步细分, 通过把候选标志点与人脸标志点模型进行匹配, 实现标志点的精确定位. 首先在CASIA数据集对该方法的标志点定位精度进行测试, 然后在UND/FRGC v2.0数据集对该方法与其他方法进行比较. 实验结果表明该方法在姿态和表情变化很大的条件下具有高精度和高鲁棒性.     

姿态和表情变化下的三维人脸标志点定位（英文）

三维人脸标志点定位在人脸识别、人脸跟踪、人脸建模、表情分析等方面具有非常重要的作用.然而,在姿态和表情变化很大的条件下进行标志点定位,这仍然是一个很具挑战性的课题.本文提出一种对姿态和表情不敏感的三维人脸标志点定位方法,利用HK曲率分析检测出候选标志点,根据对面部形状的先验知识,提出一种基于人脸几何结构的分类策略对候选标志点进一步细分,通过把候选标志点与人脸标志点模型进行匹配,实现标志点的精确定位.首先在CASIA数据集对该方法的标志点定位精度进行测试,然后在UND/FRGC v2.0数据集对该方法与其他方法进行比较.实验结果表明该方法在姿态和表情变化很大的条件下具有高精度和高鲁棒性.     

基于UWB/AOA/TDOA的WSN节点三维定位算法研究

为了将二维定位算法AOA和TDOA拓展成三维定位算法,文中提出了一种基于AOA/TDOA和UWB传输技术的WSN节点三维定位算法。该算法采用二维的AOA测角算法测量未知节点与信标节点之间的角度,采用TDOA算法测量未知节点与信标节点之间的距离,在测角、测距的过程中采用UWB通信技术来传输探测信号,使得探测信号具有较高的时间分辨率,从而提高测角、测距精度,最后基于文中提出的待测节点三维坐标计算方法求解出待测节点的三维坐标。为了验证算法的有效性,在Matlab软件中进行了仿真实验。结果表明：新算法定位精度相比于AOA算法、TDOA算法都有大幅度提高。理论和实践皆表明：新算法具有较高的定位精度,能够满足未知节点在三维空间中的定位需求。     

基于相机空间点约束的机器人工具标定方法

工具标定就是确定工具坐标系相对于机器人末端坐标系的变换矩阵,但传统的解决方案是通过人工示教点约束的方法,为此提出一种基于视觉相机空间的自动工具标定方法。在末端工具上增加特征点如圆环标志,利用相机建立机器人三维空间与相机二维空间之间的关系,通过自动的三维空间视觉定位,实现对圆环标志的中心点的点约束,视觉定位不需要相机的标定等繁琐过程。基于机器人的正运动学和相机空间点约束完成工具中心点(TCP)求解。重复实验的标定误差小于0.05 mm,实验的绝对定位误差小于0.1 mm,验证了基于相机空间定位的工具标定具有较高的可重复性以及可靠性。     

Automatic work objects calibration via a global–local camera system

In a human–robot collaborative manufacturing application where a work object can be placed in an arbitrary position, there is a need to calibrate the actual position of the work object. This paper presents an approach for automatic work-object calibration in flexible robotic systems. The approach consists of two modules: a global positioning module based on fixed cameras mounted around robotic workspace, and a local positioning module based on the camera mounted on the robot arm. The aim of the global positioning is to detect the work object in the working area and roughly estimate its position, whereas the local positioning is to define an object frame according to the 3D position and orientation of the work object with higher accuracy. For object detection and localization, coded visual markers are utilized. For each object, several markers are used to increase the robustness and accuracy of the localization and calibration procedure. This approach can be used in robotic welding or assembly applications.     

An indoor localization dataset and data collection framework with high precision position annotation

We introduce a novel technique and an associated high resolution dataset that aim to precisely evaluate wireless signal based indoor positioning algorithms. The technique implements an augmented reality (AR) based positioning system that is used to annotate the wireless signal parameter data samples with high precision position data. We track the position of a practical and low cost navigable setup of cameras and a Bluetooth Low Energy (BLE) beacon in an area decorated with AR markers. We maximize the performance of the AR-based localization by using a redundant number of markers. Video streams captured by the cameras are subjected to a series of marker recognition, subset selection and filtering operations to yield highly precise pose estimations. Our results show that we can reduce the positional error of the AR localization system to a rate under 0.05 meters. The position data are then used to annotate the BLE data that are captured simultaneously by the sensors stationed in the environment, hence, constructing a wireless signal dataset with the ground truth, which allows a wireless signal based localization system to be evaluated accurately.     

基于序列帧的光学运动捕捉系统及实现

首先,给出了系统的结构图。然后,提出了光学运动捕捉系统中关键技术的解决方法。利用卡尔曼滤波算法进行标记点预测和跟踪,提高了跟踪的准确性。在三维重建之前还需要进行摄像机的三维重建,以便准确地得出标记点的空间位置,提出了标定摄像机的实用方法。由于误差的存在,对三维重建理想状态下的方法进行了扩充,使三维重建更易于实现。实验证明,文中提到的方法能得到理想的数据。     

Robot calibration using a 3D vision-based measurement system with a single camera

One of the problems that slows the development of off-line programming is the low static and dynamic positioning accuracy of robots. Robot calibration improves the positioning accuracy and can also be used as a diagnostic tool in robot production and maintenance. This work presents techniques for modeling and performing robot calibration processes with off-line programming using a 3D vision-based measurement system. The measurement system is portable, accurate and low cost, consisting of a single CCD camera mounted on the robot tool flange to measure the robot end-effector pose relative to a world coordinate system. Radial lens distortion is included in the photogrammetric model. Scale factors and image centers are obtained with innovative techniques, making use of a multiview approach. Results show that the achieved average accuracy using a common off-the-shelf CCD camera varies from 0.2 to 0.4 mm, at distances from 600 to 1000 mm from the target, respectively, with different camera orientations. Experimentation is performed on two industrial robots to test their position accuracy improvement using the calibration system proposed: an ABB IRB-2400 and a PUMA-500. The robots were calibrated at different regions and volumes within their workspace achieving accuracy from three to six times better when comparing errors before and after calibration, if measured locally. The proposed off-line robot calibration system is fast, accurate and easy to set up.     

Automated camera planning to film robot operations

Automatic 3D animation generation techniques are becoming increasingly popular in different areas related to computer graphics such as video games and animated movies. They help automate the filmmaking process even by non professionals without or with minimal intervention of animators and computer graphics programmers. Based on specified cinematographic principles and filming rules, they plan the sequence of virtual cameras that the best render a 3D scene. In this paper, we present an approach for automatic movie generation using linear temporal logic to express these filming and cinematography rules. We consider the filming of a 3D scene as a sequence of shots satisfying given filming rules, conveying constraints on the desirable configuration (position, orientation, and zoom) of virtual cameras. The selection of camera configurations at different points in time is understood as a camera plan, which is computed using a temporal-logic based planning system (TLPlan) to obtain a 3D movie. The camera planner is used within an automated planning application for generating 3D tasks demonstrations involving a teleoperated robot arm on the the International Space Station (ISS). A typical task demonstration involves moving the robot arm from one configuration to another. The main challenge is to automatically plan the configurations of virtual cameras to film the arm in a manner that conveys the best awareness of the robot trajectory to the user. The robot trajectory is generated using a path-planner. The camera planner is then invoked to find a sequence of configurations of virtual cameras to film the trajectory.     

手眼立体视觉的算法与实现

传统的定位方法要求标定出摄像机的内外参数,本文基于直接将图像坐标映射到机器 人参考坐标的“黑箱”思想,提出了末端执行器到机器人参考坐标系的一个恒定旋转矩阵． 使用恒定旋转矩阵使得目标三维定位的算法与标定参数的过程大大简化,同时具有较高的定 位精度．本文提出的三维目标定位方法同样可应用于移动式装配机器人和移动式操作手臂中 ．     

Reliability-based camera handoff for cooperative tracking with multiple pan-tilt cameras

We present a new handoff method for multiple pan-tilt cameras for mobile robot tracking in an indoor environment. Camera handoff is an important step to consistently maintain the visibility of a mobile robot with maximized object tracking accuracy. First, we propose a method to estimate the position of a mobile robot using single pan-tilt camera. Then, the concept of position reliability is defined to quantitatively evaluate the accuracy of position estimation and tracking ability of individual pan-tilt cameras. Position reliability is used to decide when to trigger handoff and who to response handoff in the proposed handoff algorithm. Experimental results demonstrate that four pan-tilt cameras can systematically track a mobile robot in an indoor environment using the proposed method.     

基于ORB-SLAM的室内机器人定位和三维稠密地图构建

针对在室内机器人定位和三维稠密地图构建系统中,现有方法无法同时满足高精度定位、大范围和快速性要求的问题,应用具有跟踪、地图构建和重定位三平行线程的ORB-SLAM算法估计机器人三维位姿;然后拼接深度摄像头KINECT获得的三维稠密点云,提出空间域上的关键帧提取方法剔除冗余的视频帧;接着提出子地图法进一步减少地图构建的时间,最终提高算法的整体速度。实验结果表明,所提系统能够在大范围环境中准确定位机器人位置,在运动轨迹为50 m的大范围中,机器人的均方根误差为1.04 m,即误差为2%,同时整体速度为11帧/秒,其中定位速度达到17帧/秒,可以满足室内机器人定位和三维稠密地图构建的精度、大范围和快速性的要求。     

计算机视觉测量系统的误差模型分析

基于相机的钻孔模型，研究了相机光学系统产生的4种非线性误差，并在有径向失真和图像中心偏移失真的情况下，用模拟数据对匹配误差和不同量化等级在重建过程中的传播过程和影响作了详细讨论，为视觉测量系统达到高精度的三维重建提供了可靠的误差模型。