双目视觉基于修正卡尔曼滤波器的运动估计

研究了目标物体的远程运动估计.首先,建立了一种双目视觉系统的基于卡尔曼滤波器的目标物体运动估计的运动学模型,并且证明了双目视觉系统同步的各自连续两帧图像中至少三个对应图像点能完全确定刚性物体的运动参数和空间位置;然后,通过对状态向量中的速度分量进行再估计,提出了一种修正卡尔曼滤波器对目标物体远程运动估计的算法,与直接卡尔曼滤波器的远程运动估计相比,提高了估计的精度.将该方法运用到一种实时预测的实验中,其结果证明了该算法的有效性.     

基于区域收缩和DIRECT算法的运动分割

运动图像序列分割是计算机视觉中的一个重要问题.本文采用基于贝叶斯框架的最大后验边缘概率算法进行运动目标分割.首先,重新定义贝叶斯框架中似然函数的平滑项,并采用区域收缩算法实现迭代过程中运动目标支持区的估计.然后提出一种通过区域中心和主轴表示6参数仿射运动的模型,通过区域主轴像素估计运动参数,提高算法执行速度,将估计问题转化为一个取值有界的最优化问题,采用DIRECT算法估计运动参数.该方法与传统方法相比,提高运动参数估计的准确性和稳定性.通过仿真实验结果证明该方法的有效性.     

基于卡尔曼滤波与Zernike-facet模型的运动小目标检测

本文提出了一种新的运动小目标检测算法,该算法基于卡尔曼滤波和Zernike-facet模型。卡尔曼滤波器是一种简单和常用的状态估计快速算法,能够较为准确地对目标的运动位置、速度作出预测。本文首先利用卡尔曼滤波预测图像序列中目标的位置并得到目标搜索窗口,然后利用Zernike-facet模型检测搜索窗口中的匹配图像。仿真实验证明,这种方法是有效可行的。     

一种移动机器人对运动目标的检测跟踪方法

从序列图像中有效地自动提取运动目标区域和跟踪运动目标是自主机器人运动控制的研究热点之一.给出了连续图像帧差分和二次帧差分改进的图像HIS差分模型,采用自适应运动目标区域检测、自适应阴影部分分割和噪声消除算法,对无背景图像条件下自动提取运动目标区域.定义了一些运动目标的特征分析和计算,通过特征匹配识别所需跟踪目标的区域.采用Kalman预报器对运动目标状态的一步预测估计和两步增量式跟踪算法,能快速平滑地实现移动机器人对运动目标的跟踪驱动控制.实验结果表明该方法有效.     

基于无极卡尔曼滤波算法的雅可比矩阵估计

在基于图像的机器人视觉伺服中,采用在线估计图像雅可比的方法,不需事先知道系统的精确模型,可以避免复杂的系统标定过程。为了有效改善图像雅可比矩阵的在线估计精度,进而提高机器人的跟踪精度,针对机器人跟踪运动目标的应用背景,提出了利用无极卡尔曼滤波算法在线估计总雅可比矩阵。在二自由度的机器人视觉伺服仿真平台上,分别用卡尔曼滤波器（KF）、粒子滤波器（PF）和无极卡尔曼滤波器（UKF）三种算法进行总雅可比矩阵的在线估计。实验结果证明,使用UKF算法的跟踪精度优于其他两种算法,时间耗费仅次于KF算法。     

一种新的步态图像序列分割算法

在运动目标步态识别中,从步态图像序列中提取出完整的人体运动轮廓对特征提取、目标分类和目标识别等有着非常重要的意义。提出了一种新的运动目标分割算法：首先应用改进的块匹配算法进行运动估计;然后运用分水岭算法把当前帧图像分割成许多封闭而不重叠的小区域;最后运用仿射参数模型进行运动块区域合并。在CMU步态数据库中采用基准算法进行的实验表明,运用所提出的算法能够提取出完整的人体轮廓,进一步提高步态识别的识别率。     

基于马尔可夫随机场的运动分割研究

运动对象的分割技术一直是图像处理和计算机视觉领域的重要研究课题。采用一种将运动估计方法与马尔可夫随机场（MRF）模型相结合的运动分割方法。采用鲁棒统计技术与误差模型相结合构成运动估计的目标函数,运动模型为仿射运动,通过过松弛算法获得每种运动的运动参数;根据误差最小原则确定运动对应区域的初值,采用马尔可夫随机场（MRF）模型对运动估计结果进行平滑去噪。最后给出了该方法在通用图像实例上的实验结果。     

基于Markov随机场的运动目标快速分割

提出了一种基于MRF模型自适应运动目标图像分割方法，该法采用高斯混合模型描述视频序列的差分图像，用模拟退火快速EM算法对高斯分布的参数进行估计，在此基础上建立MRF模型，利用此模型构建能量函数，ICM算法把图像用一个能量函数取到最小值的组态来表示。     

乒乓球机器人的视觉伺服系统

视觉伺服的乒乓球机器人系统作为典型的"手眼系统",是研究高速视觉感知和快速伺服运动的理想平台,其涉及的高速物体识别跟踪、快速精确轨迹预测及机械臂伺服准确回球等关键技术在工业、军事等领域有广泛的应用前景.本文提出了乒乓球机器人的高速视觉伺服系统实现方法,包括基于特征直方图统计和快速轮廓搜索的目标识别算法,基于模型参数学习和自适应模型调整的物体运动状态估计和轨迹预测算法,及基于轨迹预测的灵巧臂回球规划算法.通过实验验证了各算法的实时性和高效性,并在165cm高的仿人机器人"悟"和"空"上成功实现了双机器人对打和与人对打任务.     

交互式多模型算法的MT-R机器人视觉跟踪

针对机器人的视觉跟踪问题,提出了一种基于交互式多模型算法的视觉跟踪方法。该方法采用HSV颜色模型,通过交互式多模型算法进行滤波估计,获得目标的运动属性。利用交互式多模型算法对目标的位置进行一步或者N步预测,在获得下一帧的观测值后,在预测位置的区域进行目标搜索,可减少搜索区域,节省搜索时间,增加了跟踪的实时性。使用该方法对机器人足球比赛中的红色球进行搜索跟踪。实验结果表明,应用该方法可获得目标的运动属性,能快速搜索到运动目标,并能进行准确跟踪。     

Adaptive robust estimation of affine parameters from block motion vectors

In this paper, we propose an affine parameter estimation algorithm from block motion vectors for extracting accurate motion information with the assumption that the undergoing motion can be characterized by an affine model. The motion may be caused either by a moving camera or a moving object. The proposed method first extracts motion vectors from a sequence of images by using size-variable block matching and then processes them by adaptive robust estimation to estimate affine parameters. Typically, a robust estimation filters out outliers (velocity vectors that do not fit into the model) by fitting velocity vectors to a predefined model. To filter out potential outliers, our adaptive robust estimation defines a continuous weight function based on a Sigmoid function. During the estimation process, we tune the Sigmoid function gradually to its hard-limit as the errors between the model and input data are decreased, so that we can effectively separate non-outliers from outliers with the help of the finally tuned hard-limit form of the weight function. Experimental results show that the suggested approach is very effective in estimating affine parameters reliably.     

基于全景视觉的移动机器人的运动目标检测

在动态背景下的运动目标检测中,由于目标和背景两者都是各自独立运动的,在提取前景运动目标时需要考虑由移动机器人自身运动引起的背景变化。仿射变换是一种广泛用于估计图像间背景变换的方法。然而,在移动机器人上使用全方位视觉传感器(ODVS)时,由于全方位图像的扭曲变形会 造成图像中背景运动不一致,无法通过单一的仿射变换描述全方位图像上的背景运动。将图像划分为网格窗口,然后对每个窗口分别进行仿射变换,从背景变换补偿帧差中得到运动目标的区域。最后,根据ODVS的成像特性,通过视觉方法解析出运动障碍物的距离和方位信息。实验结果表明,提出的方法能准确检测出移动机器人360°范围内的运动障碍物,并实现运动障碍物的精确定位,有效地提高了移动机器人的实时避障能力。     

A Stochastic Approach for Blurred Image Restoration and Optical Flow Computation on Field Image Sequence

The blur in target images caused by camera vibration due to robot motion or hand shaking and by object(s) moving in the background scene is different to deal with in the computer vision system.In this paper,the authors study the relation model between motion and blur in the case of object motion existing in video image sequence,and work on a practical computation algorithm for both motion analysis and blut image restoration.Combining the general optical flow and stochastic process,the paper presents and approach by which the motion velocity can be calculated from blurred images.On the other hand,the blurred image can also be restored using the obtained motion information.For solving a problem with small motion limitation on the general optical flow computation,a multiresolution optical flow algoritm based on MAP estimation is proposed. For restoring the blurred image ,an iteration algorithm and the obtained motion velocity are used.The experiment shows that the proposed approach for both motion velocity computation and blurred image restoration works well.     

Qualitative detection of motion by a moving observer

Two complementary methods for the detection of moving objects by a moving observer are described. The first is based on the fact that, in a rigid environment, the projected velocity at any point in the image is constrained to lie on a 1-D locus in velocity space whose parameters depend only on the observer motion. If the observer motion is known, an independently moving object can, in principle, be detected because its projected velocity is unlikely to fall on this locus. We show how this principle can be adapted to use partial information about the motion field and observer motion that can be rapidly computed from real image sequences. The second method utilizes the fact that the apparent motion of a fixed point due to smooth observer motion changes slowly, while the apparent motion of many moving objects such as animals or maneuvering vehicles may change rapidly. The motion field at a given time can thus be used to place constraints on the future motion field which, if violated, indicate the presence of an autonomously maneuvering object. In both cases, the qualitative nature of the constraints allows the methods to be used with the inexact motion information typically available from real-image sequences. Implementations of the methods that run in real time on a parallel pipelined image processing system are described.     

移动机器人视觉定位方法的研究与实现

针对移动机器人的局部视觉定位问题进行了研究。首先通过移动机器人视觉定位与目标跟踪系统求出目标质心特征点的位置时间序列，然后在分析二次成像法获取目标深度信息的缺陷的基础上，提出了一种获取目标的空间位置和运动信息的方法。该方法利用序列图像和推广卡尔曼滤波，目标获取采用了HIS模型。在移动机器人满足一定机动的条件下，较精确地得到了目标的空间位置和运动信息。仿真结果验证了该方法的有效性和可行性。     

一种光学式运动捕捉系统下的物体运动数据捕捉方法研究

多相机视觉运动捕捉系统能通过捕捉标记点的空间坐标来获得运动物体的运动学参数,文中提出了一种基于多相机运动捕捉系统下的通用物体运动数据捕捉方法;首先根据3个标记点组成固定模型获取物体运动过程中对应标记点的瞬时坐标,然后通过向量法求解出被测物体在运动过程中各采集点对应的物体位姿,然后通过卡尔曼滤波方法消除运动捕捉过程中的系统和环境误差的影响,获得平滑的物体位姿运动轨迹,并根据滤波数据计算出物体在各采集点对应的速度、加速度、角速度、角加速度;最后基于协作机器人进行物体的运动数据捕捉实验,验证了所提出物体运动数据捕捉方法的正确性。     

A Group-Theoretic Construction with Spatiotemporal Wavelets for the Analysis of Rotational Motion

This paper presents a group-theoretic approach for the analysis of rotational motion in image sequences. This method relies on Lie algebras, Lie groups and Lie group representations to provide not only the continuous wavelets but also the related tools of harmonic analysis. This approach can be referred to research works presented in J.S. Byrnes et al. (Wavelets and their Applications, Kluwer Academic Publishers, 1994) who strongly influenced this topic. For the purpose of modeling motion transformations, this paper introduces the concepts of Lie algebras and Lie groups as the actual mathematical foundations of all the observable kinematics embedded in spatio-temporal signals. Rotational motion analysis focuses on the estimation of angular velocity and angular accelerations embedded in image sequences. Rotational motion is usually carried on a trajectory, the complete problem at hand consists in estimating not only the angular velocity and its temporal derivatives but also the position, the translational velocity and its temporal derivatives along the carrier trajectory. The paper starts with the usual affine and Galilei groups and proceeds by successive extensions and sections to the rotational group. The theory of group representations is central to provide families of continuous wavelets, special functions, PDE's, ODE's and integral transforms as new mathematical tools of motion analysis in image sequence to perform optimal and selective detection, estimations, tracking, and reconstructions. This paper defines rotational wavelets and proposes a structured approach to perform estimation and tracking in image sequences which fits to Kalman filters. Simulations on real digital image sequences are also presented with tracking and estimation.     

Fusing Visual and Inertial Sensing to Recover Robot Ego‐motion

A method for estimating mobile robot ego‐motion is presented, which relies on tracking contours in real‐time images acquired with a calibrated monocular video system. After fitting an active contour to an object in the image, 3D motion is derived from the affine deformations suffered by the contour in an image sequence. More than one object can be tracked at the same time, yielding some different pose estimations. Then, improvements in pose determination are achieved by fusing all these different estimations. Inertial information is used to obtain better estimates, as it introduces in the tracking algorithm a measure of the real velocity. Inertial information is also used to eliminate some ambiguities arising from the use of a monocular image sequence. As the algorithms developed are intended to be used in real‐time control systems, considerations on computation costs are taken into account. © 2004 Wiley Periodicals, Inc.     

移动机器人实时目标跟踪系统设计与实现

针对单目视觉移动机器人目标跟踪的实时性和鲁棒性要求,提出了基于Kalman滤波器的改进Camshift算法检测和定位目标.将Kalman预测值作为目标初始位置,补偿摄像头和目标相对运动导致的目标在图像中的偏移.在系统“跟丢”后判断目标丢失的原因,根据原因自适应拓展搜索窗口作为Cam-shift算法的下一帧初始搜索窗口.为了验证改进算法的有效性,自主研制了一种应用该算法的履带式机器人实时目标跟踪系统.实验结果表明:该系统具有很好的鲁棒性和实时性.