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1.5V resistive fuse for image smoothing and segmentation

ELECTRONICS LETTERS 1997年第10期33卷 851-852页

作者： Athreya, JKV Gregson, PH Department of Electrical Engineering Computer Vision and Image Processing Laboratory Technical University of Nova Scotia Halifax Canada

A 1.5V resistive fuse for image smoothing and segmentation using bulk-driven MOSFETs is presented. The circuit switches on only if the differential voltage applied across its input terminals is less than a set voltage;it switches off if the differential voltage is higher than the set value. The useful operation range of the circuit is 0.4V with a supply voltage of 1.5V and threshold voltages of V-Tn = 0.828V and V-Tp = -0.56V for n and g channel MOSFETs, respectively.

关键词： image processing segmentation (image processing)

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Compensation of teleoperator modeling uncertainties with a sliding mode controller

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robotics AND computer-INTEGRATED MANUFACTURING 1997年第1期13卷 9-20页

作者： Tzafestas, SG Prokopiou, PA Intelligent Robotics and Automation Laboratory Computer Science Division Department of Electrical and Computer Engineering National Technical University of Athens Zografou Campus 15773 Athens Greece

The response of a previously proposed teleoperator system, which was not based on the traditional notion of telepresence but on an original form of kinesthetic feedback, is tested under modeling errors of up to 50%. The original system is enhanced by replacing the previous controller of each robot with a sliding mode robust one. A two-stage approach is employed: a desired trajectory is first generated and then tracked by the controller. The difficulties incurred for the man/machine cooperation are discussed. This extension of the original teleoperator architecture is tested through simulations and compared with a twin system based on neural controllers, presented elsewhere. (C) 1997 Elsevier Science Ltd.

关键词： Man machine systems

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Visually guided navigation

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robotics AND AUTONOMOUS SYSTEMS 1997年第1期21卷 37-50页

作者： Kosecka, J Robotics laboratory Department of Electrical Engineering and Computer Science 333 Cory Hall 98 UC Berkeley Berkeley CA 94720-1772 USA

Rich sensory information, robust control strategies and proper representation of the environment are crucial for successful navigation of the mobile robot. We propose a model of the environment which is suitable for global navigation using visual sensing. At the lowest level of interaction of the robot with the environment we employ visual servoing techniques which facilitate robust local navigation by means of relative positioning. Further we demonstrate how to use these local control strategies in a global setting. The environment is represented in terms of place graph, where the nodes correspond to places and arcs have associated servoing strategies for moving from one place to another. The global navigation is expressed as a sequence of relative positioning tasks obtainable from the search of a place graph. The proposed model facilitates generation of motion plans which can be executed in a robust manner thanks to the presence of the sensory information in the feedback loop.

关键词： visual servicing motion planning navigation

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Calibrating a multi-manipulator robotic system (vol 4, pg 20, 1997)

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IEEE robotics & AUTOMATION MAGAZINE 1997年第2期4卷 44-44页

作者： Bonitz, RG Hsia, TC Jet Propulation Laboratory Pasadena CA USA Systems.Control and Robotics Laboratory Department of Electrical and Computer Engineering University of California Davis CA USA

A simple, but effective, method of calibrating a multimanipulator robotic system is introduced. The algorithm uses precisely machined calibration plates which are inexpensive to manufacture and require no measuring instrumentation. The method is tested on a dual-arm system which resulted in an order of magnitude reduction in the pose error. Coordinated dual-arm manipulation experiments are conducted using the calibrated kinematic model to validate the usefulness of the calibration process.

关键词： Calibration Robot kinematics Manipulators robotics and automation Force control End effectors Acoustic measurements Testing Coordinate measuring machines Position measurement

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Exact multichannel blind image restoration

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IEEE SIGNAL PROCESSING LETTERS 1997年第8期4卷 217-220页

作者： Pai, HT Bovik, AC Laboratory for Vision Systems Department of Electrical and Computer Engineering University of Texas Austin Austin TX USA University of Texas at Austin Austin TX US

Recently, Liu and Xu proposed a bind symbol estimation algorithm in digital communications. If all the channels are linear time-invariant finite impluse response (LTI FIR) filters, this algorithm can estimate symbols exactly when the channels and the input symbols satisfy some loose restrictions. We extend this algorithm to two dimensions, and in particular, to multichannel (noise free) blind image restoration. Assuming linear FIR blur functions, given at least three blurred versions of the same image, and loose restrictions (different from those in [1]) on the original image and on the blur functions, the original image can be exactly recovered, up to a scalar multiplier.

关键词： blind restoration deconvolution exact restoration image restoration

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Two-stage neural network for volume segmentation of medical images

Two-stage neural network for volume segmentation of medical ...

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1997 IEEE International Conference on Neural Networks (ICNN 97)

作者： Ahmed, MN Farag, AA Computer Vision and Image Processing Laboratory University of Louisville Department of Electrical Engineering Louisville KY 40292 United States

ISBN: (纸本)0780341236

In this paper, we present a new system to segment and label CT/MRI Brain slices using feature extraction and unsupervised clustering. In this technique, each voxel is assigned a feature pattern consisting of a scaled family of differential geometrical invariant features. The invariant feature pattern is then assigned to a specific region using a two-stage neural network system. The first stage is a self-organizing principal components analysis (SOPCA) network that is used to project the feature vector onto its leading principal axes found by using principal components analysis. This step provides an effective basis for feature extraction. The second stage consists of a self-organizing feature map (SOFM) which will automatically cluster the input vector into different regions. The optimum number of regions (clusters) is obtained by a model fitting approach. Finally, a 3D connected component labeling algorithm is applied to ensure region connectivity. Implementation and performance of this technique are presented. Compared to other approaches, the new system is more accurate in extracting 3D anatomical structures of the brain, and can be apdated to real-time imaging scenarios.

关键词： segmentation pattern analysis learning in vision

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On an effective design approach of Cartesian space neural network control for robot manipulators

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ROBOTICA 1997年第3期15卷 305-312页

作者： Jung, S Hsia, TC Robotics Research Laboratory Department of Electrical and Computer Engineering University of California Davis CA 95616 USA. E-mail: hsia@ece.ucdavis.edu and jung@ece.ucdavis.edu

It is well known that computed torque robot control is subjected to performance degradation due to uncertainties in robot model, and application of neural network (NN) compensation techniques are promising. In this paper we examine the effectiveness of neural network (NN) as a compensator for the complex problem of Cartesian space control. In particular we examine the differences in system performance of accurate position control when the same NN compensator is applied at different locations in the controller structure. It is found that using NN to modify the reference trajectory to compensate for model uncertainties is much more effective than the traditional approach of modifying control input or joint torque/force. To facilitate the analysis, new NN training signal is introduced and used for all cases. The study is also extended to non-model based Cartesian control problems. Simulation results with three-link rotary robot are presented and performances of different compensating locations are compared.

关键词： neural network robot control Cartesian space design

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From multidimensional signals to the generation of responses

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International Workshop on Algebraic Frames for the Perception and Action Cycle, AFPAC 1997

作者： Granlund, Gösta H. Computer Vision Laboratory Department of Electrical Engineering Linköping University LinköpingS-581 83 Sweden

ISBN: (纸本)3540635173

It has become increasingly apparent that perception cannot be treated in isolation from the response generation, firstly because a very high degree of integration is required between different levels of percepts and corresponding response primitives. Secondly, it turns out that the response to be produced at a given instance is as much dependent upon the state of the system, as the percepts impinging upon the system. The state of the system is in consequence the combination of the responses produced and the percepts associated with these responses. Thirdly, it has become apparent that many classical aspects of perception, such as geometry, probably do not belong to the percept domain of a vision system, but to the response domain. There are not yet solutions available to all of these problems. In consequence, this overview will focus on what are considered crucial problems for the future, rather than on the solutions available today. It will discuss hierarchical architectures for combination of percept and response primitives, and the concept of combined percept-response invariances as important structural elements for vision. It will be maintained that learning is essential to obtain the necessary flexibility and adaptivity. In consequence, it will be argued that invariances for the purpose of vision are not geometrical but derived from the percept-response interaction with the environment. The issue of information representation becomes extremely important in distributed structures of the types foreseen, where uncertainty of information has to be stated for update of models and associated data. © Springer-Verlag Berlin Heidelberg 1997.

关键词： Invariance

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MoNiF: a modular neuro-fuzzy controller for race car navigation

MoNiF: a modular neuro-fuzzy controller for race car navigat...

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IEEE International Symposium on Computational Intelligence in robotics and Automation (CIRA)

作者： K.C. Ng R. Scorcioni M.M. Trivedi N. Lassiter Computer Vision and Robotics Research Laboratory Electrical anad Computer Engineering Department University of California San Diego CA USA

This paper characterizes how well the modular neuro-fuzzy controller, MoNiF, can perform in robotic applications by testing it in a race-car simulator. The performance of this controller is compared with that of a neural network controller (NNC) and the best programmed car (the ideal car). During the phase of learning from the ideal car, MoNiF reaches its stable performance (when it demonstrates good control) at lap 300; while the NNC requires 700 laps. Without further learning and when competing in the same learning track, MoNiF completes 20 laps of the track about 24 seconds later than the ideal car but 29 second ahead of the NNC car. However, when they all are competing in different unfamiliar tracks, MoNiF performs comparably to the ideal car, while NNC has completely lost its ability to drive. Observing the behaviors of NNC and MoNiF, we conclude that MoNiF learns to refine the output of expert rules and thus can drive in most tracks. Meanwhile NNC learns to drive in a particular track but loses its generality for other tracks. It is shown that this modular control method, equipped with the pretrained knowledge of only few simple expert rules, learns much faster than a NNC without any apriori knowledge.

关键词： Navigation Neural networks computer vision Robot vision systems Application software computer simulation Target tracking Laboratories Performance evaluation Testing

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Control of articulated vehicle for mining applications: modeling and laboratory experiments

Control of articulated vehicle for mining applications: mode...

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IEEE Conference on Control Technology and Applications (CCTA)

作者： V. Polotski A. Hemami Department of Electrical and Computer Engineering Perception and Robotics Laboratory Montreal QUE Canada

The paper presents the theoretical analysis and experimental results of path tracking control of a class of vehicles widely used in underground mining operations. A vehicle consists of the front and rear units hinged together, where each unit has only one pair of nonsteerable wheels. Steering is performed by changing the angle between the front and rear units by means of a (pair of) hydraulic cylinders (linear actuators). In operation this vehicle moves in either forward or backward directions. Path tracking control problem is of the main importance in order to follow the relatively narrow mining corridors. It consists of using the sensory information to measure the deviations in position and orientation from the path to be followed. Based upon these two tracking errors a feedback system must govern the appropriate steering action.

关键词： Laboratories Wheels Remotely operated vehicles Mobile robots Motion analysis Automation Vehicle dynamics Axles Application software Hydraulic actuators

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