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IMPROVED INITIAL APPROXIMATION AND INTENSITY-GUIDED DISCONTINUITY DETECTION IN VISIBLE-SURFACE RECONSTRUCTION

computer vision GRAPHICS AND IMAGE PROCESSING 1989年第3期47卷 292-326页

作者： JOU, JY BOVIK, AC Laboratory for Vision Systems Computer and Vision Research Center Department of Electrical and Computer Engineering The University of Texas at Austin Austin Texas 78712-1084 USA

Techniques are described for improving the speed and accuracy of iterative visible-surface reconstruction algorithms. In particular, the importance of obtaining accurate early information is emphasized, both in the initial surface approximation and in the early localization of surface discontinuities. The first of these goals is attained using a simple technique known as constraint expansion , which yields a good initial approximation while accounting for detected discontinuities. The second goal is attained by using the locations of the image irradiance edges as a guide in locating potential discontinuities. Discontinuity detection in later stages of computation is augmented by a double-thresholding strategy and discontinuity backtracking.

关键词： Image Processing

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EXPERIMENTS IN SEGMENTING TEXTON PATTERNS USING LOCALIZED SPATIAL FILTERS

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PATTERN RECOGNITION 1989年第6期22卷 707-717页

作者： CLARK, M BOVIK, AC Laboratory for Vision Systems Computer and Vision Research Center Department of Electrical and Computer Engineering The University of Texas at Austin Austin TX 78712-1084 U.S.A

In this paper we apply a previously developed model of texture segmentation using multiple spatially and spectrally localized filters, known as Gabor filters, to the analysis of textures composed of elementary image features known as textons. It is found that for regularly- or irregularly-spaced texton patterns, the segmentation approach works well, in the sense that it is in accordance with visual segmentation. Differences in texton spacing, size, orientation, and phase are all found to lead to successful segmentations.

关键词： Texton Texture segmentation Localized spatial filter Gabor filter

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A NEW TECHNIQUE FOR ROBUST-CONTROL OF SERVO SYSTEMS

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IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS 1989年第1期36卷 1-7页

作者： HSIA, TCS Robotics Research Laboratory Department Electrical Engineering and Computer Science University of California Davis Davis CA USA

The robust controller has very simple structures and can be divided into two separate parts: a servo controller and an auxiliary controller. The two controllers are designed independently. The function of the auxiliary controller is to cancel out the plant uncertainties directly without the use of the high loop gain principle. Interpretation of robot controller as a signal-synthesis adaptive controller is given. Practical implementation issues of the auxiliary controller are discussed. Simulations of a design example with large parameter uncertainty, nonlinearity, and external disturbance are presented to demonstrate the effectiveness of the design technique. This technique is further tested with success in an experimental study of joint position control of a PUMA 560 robot arm.< >

关键词： Robust control Servomechanisms Uncertainty DC motors Servomotors Adaptive control Robot control Programmable control Uncertain systems Testing

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ADAPTIVE EDGE-FOLLOWING FORCE CONTROL OF AN INDUSTRIAL ROBOT

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robotics AND computer-INTEGRATED MANUFACTURING 1989年第4期6卷 331-337页

作者： LIOU, JN JAMSHIDI, M STARR, GP CAD Laboratory for Systems/Robotics Department of Electrical and Computer Engineering University of New Mexico Albuquerque NM 87131 United States Robotic Research Laboratory Department of Mechanical Engineering University of New Mexico Albuquerque NM 87131 United States

Control of tool-workpiece interaction force is of vital importance in automated assembly. Using a simple linear continuous model of an edge-following system to predict the appropriate accomodation gains in a force control loop, previous work has shown that force control by accomodation is feasible. Following up this work, this paper describes the analysis, simulation and implementation of an adaptive force control in a two-dimensional edge-following task with a PUMA 560 robot and wrist force sensor. First, a discrete-time model of an edge-following system is developed and then used as the plant; second, a model reference adaptive control (MRAC) scheme is applied to achieve both tracking and regulation purposes. The reference (tracking) model can be determined by experimental reference input and desired model output information; the reference (regulation) model can be obtained by simulation to smooth out the plant output and improve the augmented filtered plant-model error. Study is done on the values of the adaptation gains in the adaptive mechanism, and hence can be adjusted to insure the best plant output performance.

关键词： Robots, Industrial

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Optimal object localization using dual number quaternions 7

Optimal object localization using dual number quaternions

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Applications of Artificial Intelligence VII 1989

作者： Walker, Michael W. Shao, Lejun Volz, Richard A. Robotics Research Laboratory Electrical Engineering and Computer Science Department University of Michigan Ann ArborMI48109-2110 United States

This paper presents a new algorithm for determining the position and orientation of objects. The problem is formulated as an optimization problem using dual number quaternions. It is shown that this reduces to an eigenvalue problem for which standard software library routines can be used to obtain the solution. © 1989 SPIE. All rights reserved.

关键词： Eigenvalues and eigenfunctions

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Multi-spectral scale and rotation invariant associative memory method for pattern recognition

Multi-spectral scale and rotation invariant associative memo...

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Optics, Illumination, and Image Sensing for Machine vision III 1988

作者： Kimball, Steven F. Messner, Richard A. University of New Hampshire Synthetic Vision and Pattern Analysis Laboratory Department of Electrical and Computer Engineering DurhamNH03824 United States

The method of using log-polar mapping with spectral band separation to form feature vectors for an associative memory is investigated. Log-polar mapping is used to provide the scale and rotation invariant properties. This reduces the teaching time and total capacity requirement for the associative memory because all orientations and sizes of the target object need not be learned. The images are also broken down into spatial frequency bands. The use of this technique is motivated by evidence that similar processes occur in the human visual system. Suspected benefits include enhanced recognition in the presence of noise and improved network robustness. Simulation results are presented for the case of character recognition. © 1989 SPIE. All rights reserved.

关键词： Associative processing

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Image segmentation using human visual system properties with applications in image compression

Image segmentation using human visual system properties with...

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Human vision, Visual Processing, and Digital Display 1989

作者： Peterson, Heidi A. Rajala, Sarah A. Delp, Edward J. Computer Vision and Image Processing Laboratory School of Electrical Engineering Purdue University West LafayetteIN47907 United States Department of Electrical and Computer Engineering North Carolina State University RaleighNC27695 United States

Many image compression techniques involve segmentation of a gray level image. With such techniques, information is extracted that describes the regions in the segmented image, and this information is then used to form a coded version of the image. In this paper we present a region-growing-based segmentation technique that incorporates human visual system properties, and describe the use of this technique in image compression. We also discuss the effect of requantizing a segmented image. Requantization of a segmented image is useful because it can lead to a reduction in the number of bits required to code the description of the regions in the segmented image. This results in a lower data rate. We show that the number of gray levels in a segmented image can be reduced by a factor of at least twelve, without noticeable degradation in the quality of the segmented image. This result is attributable to human visual system properties having to do with contrast sensitivity, and to the fact that requantization of a segmented image does not usually reduce significantly the number of distinct segments in the image. In addition, in this paper we explore the relationship between the number of segments in an image, and the extent of requantization possible before noticeable degradation occurs in the image. Finally, we discuss the impact of the above results on image compression algorithms, and present some experimental results. © 1989 SPIE. All rights reserved.

关键词： Image compression

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Combined vision/ultrasonics for multi-dimensional robotic tracking

Combined vision/ultrasonics for multi-dimensional robotic tr...

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Sensor Fusion: Spatial Reasoning and Scene Interpretation

作者： Luo, Ren C. Mullen, Robert E. Robotics and Intelligent Systems Laboratory Department of Electrical and Computer Engineering North Carolina State University RaleighNC27695-7911 United States

ISBN: (纸本)9780819400383

An intelligent robotic system for multi-sensor based tracking and interception of moving objects which travel at unknown velocities is presented. The capability for multi-sensor assisted object tracking has been achieved through the development of techniques to track in multiple dimensions for both the static and dynamic cases. These methods are realized via the fusion of the best attributes of visual and acoustic sensing into an effective configuration that is ideal for real time tracking purposes. The kinematic information for a moving object is extracted via end effector mounted vision and ultrasonic sensors. A hybrid position/force servo-controlled gripper developed at NCSU has been used for the system implementation. One parallel actuation gripper finger houses a fiber optics based Eye-in-Hand vision sensor, while the other accommodates an ultrasonic range sensor. The primary intent of this work is to develop approaches for performing the tasks of: generalized visual/ultrasonic tracking of known rectangular entities;3-D tracking of arbitrary pseudo-planar objects that can change orientation about the optical axis;and a real time paradigm for the tracking of motion in 3-D with variable orientation about the optical axis. This discussion includes both a description of the underlying principles and the initial experimental results.

关键词： Grippers

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Darboux frames, snakes, and super-quadrics: geometry from the bottom-up

Darboux frames, snakes, and super-quadrics: geometry from th...

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Workshop on Interpretation of 3D Scenes

作者： F.P. Ferrie J. Lagarde P. Whaite Computer Vision and Robotics Laboratory Department of Electrical Engineering McGill University Montreal QUE Canada

A representation and a computational model for deriving three-dimensional articulated volumetric descriptions of objects from laser range-finder data are described. What differentiates this work from other approaches is that it is purely bottom up, relying on general assumptions cast in terms of differential geometry. Darboux frames, snakes, and superquadrics form the basis of this representation, and curvature consistency provides the computational framework. The organization is hierarchical. Darboux frames are used to describe the local surface, while snakes are used to interpolate between features, particularly those that serve to partition a surface into its constituent parts. Superquadrics are subsequently used to characterize the 3-D shape of each surface partition. The result is a set of connected volumetric primitives which serve to describe the overall shape of an object. A set of examples showing how the approach performs on data acquired with a laser range finder is included.< >

关键词： Geometrical optics Surface fitting Computational geometry computer vision Shape Surface reconstruction Robot vision systems Laboratories Laser modes Orbital robotics

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High-speed 2-D hardware convolution architecture based on VLSI systolic arrays

High-speed 2-D hardware convolution architecture based on VL...

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IEEE Pacific Rim Conference on Communications, computers and Signal Processing

作者： D.D. Haule A.S. Malowany Computer Vision and Robotics Laboratory Department of Electrical Engineering McGill University Montreal QUE Canada

The design of a special-purpose systolic image convolution processor for use in a robot vision system is described. It presents a high-speed two-dimensional hardware convolution architecture based on VSLI systolic arrays for image processing applications. An architecture for the parallel processing of the generalized two-dimensional convolution is summarized. A VLSI convolution chip was designed to accommodate various convolution window sizes. The number of coefficients being handled is directly proportional to the number of systolic computing elements (processors) used. In the present design three such processors are configured on one VLSI chip. Signed coefficients and unsigned data of eight bits are supported. All processing and interprocessor communications are performed bit-serially. The chip design incorporates error detection during convolution, and overflow avoidance techniques are possible for maximum system autonomy. The chip is estimated to operate at a maximum frequency of 16 MHz.< >

关键词： Hardware Convolution Very large scale integration computer architecture Frequency estimation Robot vision systems Systolic arrays Image processing Parallel processing Process design

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