3-D position sensing using a passive monocular vision system

Passive monocular 3-D position sensing is made possible by a new calibration scheme that relates depth to focus blur through a composite lens and aperture model. The calibration technique enables the recovery of absolute 3-D position coordinates from image coordinates and measured focus blur. A geometric model of the camera's position and orientation in space is used to transform the camera's imaging coordinates into world coordinates. The relationship between the world coordinate system and the screen coordinate system which includes the amount of focus blur, is developed by modeling the camera imaging arrangement. The modeling proceeds first through the perspective view from a pinhole camera located anywhere in space. The camera's lens and aperture system is investigated to find the relationship between depth and focus blur. The aspect ratio of the frame image is considered. Position accuracies comparable to those in stereo based vision systems are possible without the need for solving the difficult point of correspondence problem     

汽车造型中的计算机视觉测量技术

介绍了激光扫描视觉三坐标测量技术的基本原理和系统组成,用一个车身测量实例说明了该技术在汽车车身造型中的应用。     

双摄象头三维视觉系统

本文介绍了一种较实用的双摄象头三维视觉系统.主要讨论了视场内具有六个自由度物体的定位问题.系统以Frei和Chen方法抽取边缘,并运用了非均匀量化和预加重技术.采用了改进的Moravec兴趣算子法,实现了特征点的自动抽取.基于边缘的序贯分层配准法大大缩短了配准时间.在用三维数据获取物体姿态时.根据刚体运动总结的规则解决了工作特征点和模型点匹配时的组合爆炸问题和多义性问题.     

扩展2维环境中的移动机器人多人体目标跟踪

移动机器人如何自主实现人体目标的检测与跟踪是服务机器人研究领域中的关键问题之一.在深入分析单目视觉和激光测距特性的基础上.文章首先针对室内场景进行扩展2维环境建模研究,并提出在该环境下的人体目标分段模型构建与自主辨识方法.为了有效实现对多个人体目标的同时跟踪,本文提出了一种基于非恒速运动模型和卡尔曼滤波对多人体目标进行有效匹配与跟踪的方法.实验表明本文所提方法能有效的克服目标旋转、部分遮挡和重叠以及光线明暗变化给人体目标跟踪带来的影响,具有较好的鲁棒性和实用性.     

A virtual RV-M1 robot system

Exploring a virtual model under simulated environments is the best way to learn about a real system. This is particularly true in robotics where it is quite expensive to provide the system to each individual. The interdisciplinary area of robotics is being studied commonly in various fields like electrical, computer, mechanical engineering, nanotechnology, etc. A virtual robot system can help one fully understand the controls and working of a robot. The system may also be helpful to design the path and plan the trajectory of a robot in an industrial environment or other robotics application. Virtual model of RV-M1 robot has been developed in the MATLAB environment. The virtual system performs forward kinematics and inverse kinematics in addition to providing a simulation of the robot teachbox.     

A 3-D vision system model for automatic object surface sensing

The development of a noncontact light striping (structured light) based three-dimensional, six-degrees-of-freedom vision system for automatic object surface sensing is reported. The system modeling and world-point reconstruction methodology involve homogeneous-coordinate system transformations applied in two independent stages: the video imaging stage using three-dimensional perspective transformations and the mechanical scanning stage using three-dimensional affine transformations. Concatenation of the two independent matrix models leads to a robust four-by-four, six-degrees-of-freedom system model. The reconstructed sectional contours are registered automatically in real time with respect to a common world-coordinate system as a control net for Non-Uniform Rational B-spline (NURBS) surface approximation. The reconstruction process is demonstrated by measuring the surface of a 19.5×2 ft rowing shell. A detailed statistical accuracy and precision analysis shows an average error of 0.2% (0.002) of the camera's field-of-view. System sensitivity analysis reveals a nonlinear increase of sensitivity for angles higher than 45° between the normals of the image and laser planes.     

Automatic sensor placement for model-based robot vision.

This paper presents a method for automatic sensor placement for model-based robot vision. In such a vision system, the sensor often needs to be moved from one pose to another around the object to observe all features of interest. This allows multiple three-dimensional (3-D) images to be taken from different vantage viewpoints. The task involves determination of the optimal sensor placements and a shortest path through these viewpoints. During the sensor planning, object features are resampled as individual points attached with surface normals. The optimal sensor placement graph is achieved by a genetic algorithm in which a min-max criterion is used for the evaluation. A shortest path is determined by Christofides algorithm. A Viewpoint Planner is developed to generate the sensor placement plan. It includes many functions, such as 3-D animation of the object geometry, sensor specification, initialization of the viewpoint number and their distribution, viewpoint evolution, shortest path computation, scene simulation of a specific viewpoint, parameter amendment. Experiments are also carried out on a real robot vision system to demonstrate the effectiveness of the proposed method.     

一种用于三维物体定位的视觉方法

本文讨论了一种利用视觉信息对限定性物体在三维空间定位的方法。这项工作是一个在脱机的高级机器人语言控制下验证视觉系统的一部分。本文对这一视觉系统的整体结构及其与高级机器人语言系统的关系做了概要的介绍,并且着重讨论了其中的低级视觉信息处理模块的工作原理,以及利用视觉信息对三维空间中的物体进行定位的精度     

光电混合处理系统在机器人视觉目标识别中的应用研究

分析了光电混合处理系统应用于机器人视觉识别的可行性和研究意义,评述了光电 混合处理系统在光学模式识别和机器人视觉识别领域中的研究现状．提出将JTC系统在机器 人视觉识别中的应用划分为五个研究层次,分析综述了与各类研究层次相关的形态学JTC和 三维JTC的代表性算法及JTC硬件结构,以此作为机器人视觉识别光电混合处理系统的研究基 础．     

基于2—D模型的人体运动跟踪

人体运动跟踪是图像处理和计算机视觉研究的热点问题，它在人机接口、虚拟现实、智能监控、机器人仿真等方面具有广阔应用前景，已引起越来越多学者的关注，为了实现准确的人体运动跟踪，采用了两种基于2－D模型的人体运动跟踪方法：其中，一种方法是以区域面积重合率为区域准则，采用由粗到细的匹配过程，通过建立2－D模型以实现与真实人体运动间的准确匹配；另一种是基于区域特征的2－D模型和人体各个部位的连接关系，通过确定和标记人体的各个部位，最终由2－D模型来重现真实人体的运动过程，同时采用以上两种方法，对实际人体运动进行了跟踪测试，在全身运动的整个过程中能给出较为准确的跟踪结果，表明该方法不仅能抵御噪声和灰度变化的影响，而且能大致估计出被遮挡部位的位置。     

3-D shape reconstruction in an active stereo vision system using genetic algorithms

The recovery of 3-D shape information (depth) using stereo vision analysis is one of the major areas in computer vision and has given rise to a great deal of literature in the recent past. The widely known stereo vision methods are the passive stereo vision approaches that use two cameras. Obtaining 3-D information involves the identification of the corresponding 2-D points between left and right images. Most existing methods tackle this matching task from singular points, i.e. finding points in both image planes with more or less the same neighborhood characteristics. One key problem we have to solve is that we are on the first instance unable to know a priori whether a point in the first image has a correspondence or not due to surface occlusion or simply because it has been projected out of the scope of the second camera. This makes the matching process very difficult and imposes a need of an a posteriori stage to remove false matching.In this paper we are concerned with the active stereo vision systems which offer an alternative to the passive stereo vision systems. In our system, a light projector that illuminates objects to be analyzed by a pyramid-shaped laser beam replaces one of the two cameras. The projections of laser rays on the objects are detected as spots in the image. In this particular case, only one image needs to be treated, and the stereo matching problem boils down to associating the laser rays and their corresponding real spots in the 2-D image. We have expressed this problem as a minimization of a global function that we propose to perform using Genetic Algorithms (GAs). We have implemented two different algorithms: in the first, GAs are performed after a deterministic search. In the second, data is partitioned into clusters and GAs are independently applied in each cluster. In our second contribution in this paper, we have described an efficient system calibration method. Experimental results are presented to illustrate the feasibility of our approach. The proposed method yields high accuracy 3-D reconstruction even for complex objects. We conclude that GAs can effectively be applied to this matching problem.     

广义的以物体为中心的行程编码：一种新的三维物体模型

三维物体的表达和识别是图象理解和场景分析的核心问题,三维模型在三维物体的识别和场景分析中具有十分重要的作用.三维模型应该是以物体为中心的,能够提供该场景的所有有用信息.物体的大小,形状及朝向应均可从该模型中提取得到.本文提出了一种新的三维物体模型——广义的以物体为中心的行程编码.它包括物体的GORC物理数据结构,详细的形状描述和抽象描述.物体的高层次的表达可以通过以GORC编码的物理数据直接提取得到.三维的GORC是二维的以物体为中心的行程编码在三维上的推广,它兼有物体的体积表达和表面表达的优点.三维物体的GORC模型可以很容易地由其深度信息构造得出,基于GORC的投影运算,图象代数运算以及特征提取均可非常有效地实现.     

栅格法视觉传感集成及机器人实时避障

研究移动机器人在室内环境下集成双目视觉和激光测距仪信息进行障碍物实时检测。由双目视觉系统检测环境获取视差信息,通过直接对视差信息进行地平面拟合的方法快速检测障碍物;拟合过程中采用了随机采样一致性估计算法去除干扰点的影响,提高了障碍物检测的鲁棒性。用栅格地图表示基于机器人坐标系的地平面障碍物信息并对栅格信息进行提取,最后把双目视觉与激光测距得到的栅格信息进行集成。实验表明,通过传感信息集成,移动机器人既得到了充分的障碍物信息,又保证了检测的实时性、准确性。     

3-D imaging systems and high-speed processing for robot control

Bin picking by a robot in real time requires the performance of a series of tasks that are beyond the capabilities of commercially available state-of-the-art robotic systems. In this paper, a laser-ranging sensor for real-time robot control is described. This sensor is incorporated into a robot system that has been applied to the bin-picking or random-parts problem. This system contains new technological components that have been developed recently at the Environmental Research Institute of Michigan (ERIM). These components (the 3-D imaging scanner and a recirculating cellular-array pipeline processor) make generalized real-time robot vision a practical and viable technology. This paper describes these components and their implementation in a typical real-time robot vision system application.     

3-D Locomotion control for a biomimetic robot fish

This paper concerns with 3-D locomotion control methods for a biomimetic robot fish. The system architecture of the fish is firstly presented based on a physical model of carangiform fish. The robot fish has a flexible body, a rigid caudal fin and a pair of pectoral tins, driven by several servomotors. The motion control of the robot fish are then divided into speed control, orientation control, submerge control and transient motion control, corresponding algorithms are detailed respectively. Finally, experiments and analyses on a 4-link, radio-controlled robot fish prototype with 3-D locomotion show its good performance.     

Adaptive neuro-fuzzy modeling of a soft finger-like actuator for cyber-physical industrial systems

Soft robotics is a trending area of research that can revolutionize the use of robotics in industry 4.0 and cyber-physical systems including intelligent industrial systems and their interactions with the human. These robots have notable adaptability to objects and can facilitate many tasks in everyday life. One potential use of these robots is in medical applications. Due to the soft body of these robots, they are a suitable replacement for applications like rehabilitation and exoskeletons. In this paper, we present the neuro-fuzzy modeling of a soft pneumatic finger-like actuator. This actuator is a fiber-reinforced soft robot with the shape and dimensions of a real finger and moves in planar motion. A bending sensor is used as a feedback for curvature motion of this actuator. In order to model this actuator, an adaptive neuro-fuzzy inference system is utilized to overcome the hardship in the modeling of the nonlinear performance of the soft materials. An experimental setup is designed to obtain suitable input–output data needed for modeling. The results show the applicability of the utilized method in the modeling of the soft actuator.

     

Binocular motion tracking by gaze fixation control and three-dimensional shape reconstruction

It is an easy task for the human visual system to gaze continuously at an object moving in three-dimensional (3-D) space. While tracking the object, human vision seems able to comprehend its 3-D shape with binocular vision. We conjecture that, in the human visual system, the function of comprehending the 3-D shape is essential for robust tracking of a moving object. In order to examine this conjecture, we constructed an experimental system of binocular vision for motion tracking. The system is composed of a pair of active pan-tilt cameras and a robot arm. The cameras are for simulating the two eyes of a human while the robot arm is for simulating the motion of the human body below the neck. The two active cameras are controlled so as to fix their gaze at a particular point on an object surface. The shape of the object surface around the point is reconstructed in real-time from the two images taken by the cameras based on the differences in the image brightness. If the two cameras successfully gaze at a single point on the object surface, it is possible to reconstruct the local object shape in real-time. At the same time, the reconstructed shape is used for keeping a fixation point on the object surface for gazing, which enables robust tracking of the object. Thus these two processes, reconstruction of the 3-D shape and maintaining the fixation point, must be mutually connected and form one closed loop. We demonstrate the effectiveness of this framework for visual tracking through several experiments.     

Optical guidance method for robots capable of vision and communication

The optical guidance of robots spans the research topics of robotics, computer vision, communication and real-time control. The proposed method aims to improve the accuracy of guidance along a desired route in an environment that is unknown to the robot. The key idea is to indicate the numerical coordinates of target positions by means of projecting a laser light onto the ground. In contrast with other guidance methods, which communicate the target position numerically, using optical commands avoids the need to maintain the coordinate transformation between the robot’s system and that of the environmental model (“world” reference coordinates). The image processing and communication ensure that the robot accurately follows the route indicated by laser beacons, and self-localization becomes less relevant for guidance. The experimental results have proved the effectiveness of this method.     

截面线数据的曲面蒙皮重构技术研究

为了保持曲面形状的平滑性，在曲面重构过程中经常会出现曲面形状的变异，针对带有精确截面信息的截面线数据的三维曲面重构问题，提出了一种NURBS曲面蒙皮重构方法。该方法产生一个连续的NURBS曲面，改进了传统曲面蒙皮重构方法在处理非均匀截面数据点时出现的一系列问题，通过实际系统验证了该方法的有效性。     

基于Poser的个性化人体模型运动仿真技术研究

根据服装工业对数字化动态人体模型的需要,提出了一种建立人体动态模型的新方法.该方法针对特定人体的三维扫描数据,用逆向工程软件Geomagic Studio实现个性化的三维人体NURBS曲面模型的构建,将完成后的人体曲面模型导入Poser软件,利用人体特征点确定关节位置, 建立相应的人体骨骼模型, 并将人体表面模型与骨骼模型相匹配,实现人体运动仿真.实验证明,所建立的人体动态模型在外观形状和运动姿态上具有较高的真实性, 操作简便,易于掌握.