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An Overview on Behaviour-Based Methods for AUV Control

IFAC Proceedings Volumes 2000年第21期33卷 141-146页

作者： M. Carreras J. Batlle P. Ridao G.N. Roberts Computer Vision and Robotics Group University of Girona Edifici Politècnica II Campus Montilivi 17071 Girona Spain Mechatronics Research Centre University of Wales College Newport Allt-yr-yn Campus PO Box 180 Newport South Wales NP20 5XR UK

Traditionally, deliberative reasoning methods based on a world model have been used to guide Autonomous Vehicles. Nevertheless, due to serious problems when dealing with complex and changing environments the alternative approach of reactive architectures appeared, directly coupling perception and action without any world representation. This paper describes the characteristics and variants of reactive architectures as well as four of the most suitable ones to guide Autonomous Underwater Vehicles: Schema-based approach, Subsumption, Process Description Language and Action Selection Dynamics. Each architecture is described and evaluated using an underwater simulator with an AUV model.

关键词： Autonomous Vehicles Artificial Intelligence Control Systems Marine Systems Robot navigation Vehicle Simulation

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Steering and Depth Control of an Underwater Robot Using Fuzzy-Like PD Controller

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IFAC Proceedings Volumes 2000年第21期33卷 239-244页

作者： I.S. Akkizidis G.N. Roberts P. Ridao J. Batlle Mechatronics Research Centre University of Wales College Newport Allt-yr-yn Campus PO Box 180 Newport South Wales NP9 5XR UK Computer Vision and Robotics Group Institute of Informatics and Applications Edifici Politècnica II Campus Montilivi 7071-Girona SPAIN

The design of a steering and depth control of an underwater vehicle is of interest from the point of view of motion stabilisation as well as manoeuvring performance. The paper describes how a Fuzzy-like Proportional Derivative Controller (Fuzzy-like PD Control) is used to control the course-changing and course-keeping tracking mission and motion of an underwater vehicle. The idea for this type of control architecture is to identify the optimum values, in terms of control performance and robustness, of the parameters of the F-like PD Controller. These parameters may be the scaling factors that are applied in the input/output of the PD part of the controller as well as the fuzzy sets of the fuzzy part of the controller. The values of the scaling factors for the error, the change-of-error and the control output are optimised based on experiments. In this work a method has been developed to control the yaw and depth of an underwater robot in terms of course-changing and course-keeping. The controller is synthesised in two parts. Firstly it is applied in horizontal xy and secondly in vertical xz surface. Experiments in a real environment were planned using the Taguchi Design of Experiments and performed to investigate the capabilities of the controller. The results are presented and analysed extensively.

关键词： Fuzzy like-PD Controller Yaw and Depth Control Taguchi Design of Experiments

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Microcalcification evaluation in computer assisted diagnosis for digital mammography

Microcalcification evaluation in computer assisted diagnosis...

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作者： Martí, Joan Batlle, Joan Cuffí, Xevi Español, Josep Computer Vision and Robotics Group Campus de Montilivi s/n University of Giroria 17071 Girona Spain Department of Oncology Univ. Hospital Dr. Josep Trueta Avda. de França s/n 17007 Girona Spain

In order to develop applications for visual interpretation of medical images, the early detection and evaluation of microcalcifications in digital mammograms is very important since their presence is often associated with a high incidence of breast cancers. Accurate classification into benign and malignant groups would help improve diagnostic sensitivity as well as reduce the number of unnecessary biopsies. The challenge here is the selection of the useful features to distinguish benign from malignant micro calcifications. Our purpose in this work is to analyse a microcalcification evaluation method based on a set of shape-based features extracted from the digitised mammography. The segmentation of the microcalcifications is performed using a fixed-tolerance region growing method to extract boundaries of calcifications with manually selected seed pixels. Taking into account that shapes and sizes of clustered microcalcifications have been associated with a high risk of carcinoma based on different subjective measures, such as whether or not the calcifications are irregular, linear, vermiform, branched, rounded or ring like, our efforts were addressed to obtain a feature set related to the shape. The identification of the parameters concerning the malignant character of the microcalcifications was performed on a set of 146 mammograms with their real diagnosis known in advance from biopsies. This allowed identifying the following shape-based parameters as the relevant ones: Number of clusters, Number of holes, Area, Feret elongation, Roughness, and Elongation. Further experiments on a set of 70 new mammograms showed that the performance of the classification scheme is close to the mean performance of three expert radiologists, which allows to consider the proposed method for assisting the diagnosis and encourages to continue the investigation in the sense of adding new features not only related to the shape.

关键词： Calcification (biochemistry)

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Microcalcification evaluation in computer assisted diagnosis for digital mammography

Microcalcification evaluation in computer assisted diagnosis...

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IEE Colloquium on Medical Applications of Signal Processing (Ref. No. 1999/107)

作者： J. Marti J. Batlle X. Cufi J. Espanol Computer Vision and Robotics Group-Institute of Iniormatics and ApplicationsL University of Girona Girona Spain Department of Oncology University Hospital Dr. Josep Trueta Girona Spain

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An Approach to the Urban Scene Understanding Problem Useful for Autonomous Navigation

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IFAC Proceedings Volumes 1998年第3期31卷 393-398页

作者： Jordi Freixenet Joan Martí Joan Batlle Computer Vision and Robotics Group Institute of Informatics and Applications University of Girona. Avda. Lluis Santaló s/n. 17003 - GIRONA (Spain)

This paper presents an approach to the urban scene understanding problem, providing a robust expert system able to take out natural elements such as trees or plants. The system is based on a wide range of natural features associated to seasons, weather, chromatic components, sunshine levels, etc. A particularity of the system is that it is only dealing with pixels, so video-rate processing can be achieved in an easy way, whereas others which deal with regions. Then, the proposed expert system works as a pre-processor and needs, indeed, knowledgement about the environment. Although, pixels candidates could be associated to regions in order to be useful for a further high level processing. In this sense, the system would be applied to a mobile robot in order to use the trees as landmarks for navigation.

关键词： vision computer expert systems scene understanding pixel classification natural scenes mobile robot navigation

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Sensorial and Navigation Systems for a Mobile Robot (Roger)

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IFAC Proceedings Volumes 1998年第3期31卷 279-284页

作者： Pere Ridao Josep Forest Lluís Pacheco Rafael García Xavier Cufí Computer Vision and Robotics Group Institute of Informatics and Applications University of Girona Avda. Lluis Santaló s/n 17003 - GIRONA (Spain). Tel: +34 - 72 - 418474 Fax:+34 - 72 - 418098

This paper presents basically the sensorial system, the navigation systems and the data communication of the ROGER autonomous mobile robot. This robot is capable to operate in structured indoor environments and in certain outdoor environments. The robot can place itself independently in its workspace, and can perform some basic manipulation operations. These features make possible the use this mobile robot in a wide range of applications (industrial, social, etc.)

关键词： mobile robots computer vision colour teleoperation autonomous navigation

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Mobile robot navigation using recursive motion control

Mobile robot navigation using recursive motion control

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Euromicro Workshop on Advanced Mobile Robot

作者： R. Ellepola P. Kovesi Robotics and Vision Research Group Departiiient of Computer Science University of Western Australia Nedlands WA Australia

As a mobile robot travels towards its goal, sensor input is used to modify the path of the robot to prevent collision with obstacles. In conventional programming, when an obstacle is detected by the sensors, control loops are escaped according to the requirements of the executing navigation task. Thus navigational routines have to be written in a loop form with the necessary exit conditions built in. This paper presents an alternative approach, recursive motion control. Recovery paths around obstacles are planned and executed by recursively invoking the motion control software. The approach allows multiple obstacles to be handled in a consistent manner. On completion of the obstacle avoiding sub-path(s) the level of recursion is dropped to allow resumption of the original motion.

关键词： Mobile robots Navigation Motion control Robot kinematics Robot sensing systems Robot vision systems Uncertainty Tactile sensors computer science Tracking loops

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Object-Oriented model of an open communication architecture for flexible manufacturing control 6th

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6th International Workshop on computer Aided Systems Theory, EUROCAST 1997

作者： Borangiu, Th. Tomas Balibrea, L.-M. Contreras Gonzales, L.A. Nis, Cr. Manu, M. University Politehnica of Bucharest Dept. of Computer Process Control 313 Spl. Independentei sector 6 RO-77206 Romania University of Murcia Group of Vision and Robotics Paseo Alfonso XIII Cartagena Murcia48-30203 Spain

ISBN: (纸本)3540638113

From the functional point of view. it is considered that the model of a manufacturing system consists of four layers: Machine. Data Acquisition and Control Communication, and Aggregate Application. In modeling these layers, two important initial premises have been considered. which will further allow for a modular, expandable structuring of any particular user-defined application. First, the top-down decomposition strategy, is used: "the global FMCell architecture and aggregate application are first defined as abstract, high-level objects and then decomposed into child objects during the design steps. The multiple abstraction levels for modeling the cell resources and the computer Manufacturing Control (CMC) components are used: modeling at part level, modeling at component level and modeling at application level. In order to derive the generic Object-Orientnd model of the FMCeII communication system, there have been defined an ensemble of CLASS Trees or hierarchies and a Virtual Node Tree. The ensemble of CLASS Trees defines structures and models of the manufacturing environment objects according to relationships identical to the INCLUDE hierarchy. The Virtual Node Tree (VNT) concept is used to model the modular, open-architecture of the communication layer for inter-device connection in the manufacturing environment. The class objects are: "Node" and "Level". The present paper exemplifies these OO modeling concepts by structuring the communication system of a three-station FMCell which contains two different CNC machine tools tended by one Industrial Robot, one storage and assembly workstation tended by a second Industrial Robot, which is also feeding the final assemblies for integrated quality control to a vision-based CAQC workstation. © Springer-Verlag Berlin Heidelberg 1997.

关键词： Aggregates

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Model-based objects recognition in industrial environments for autonomous vehicles control

Model-based objects recognition in industrial environments f...

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IEEE International Conference on robotics and Automation (ICRA)

作者： J. Marti J. Batlle A. Casals Computer Vision and Robotics Group Universíty of Girona Girona Spain Department of Automatic Control and Computer Engineering Polytechnic University of Catalonia Barcelona Spain

Behavior-based navigation of autonomous vehicles requires the recognition of the navigable areas and the potential obstacles. In this paper we describe a model-based objects recognition system which is part of an image interpretation system intended to assist the navigation of autonomous vehicles that operate in industrial environments. The recognition system integrates color, shape and texture information together with the location of the vanishing point. The recognition process starts from some prior scene knowledge, that is, a generic model of the expected scene and the potential objects. The recognition system constitutes an approach where different low-level vision techniques extract a multitude of image descriptors which are then analyzed using a rule-based reasoning system to interpret the image content. This system has been implemented using a rule-based cooperative expert system.

关键词： Object recognition Navigation Remotely operated vehicles Mobile robots Layout Shape Image recognition Data mining Image analysis Expert systems

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Recent progress in structured light in order to solve the correspondence problem in stereovision

Recent progress in structured light in order to solve the co...

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IEEE International Conference on robotics and Automation (ICRA)

作者： E. Mouaddib J. Batlle J. Salvi Laboratoiredes Systeèmes Automatiques Université de Picardie Amiens France Computer Vision and Robotics Group Universitat de Girona Girona Spain

We present a summary of the most significant techniques, used in the last few years, concerning the coded structured light methods employed to get 3D information. In fact, depth perception is one of the most important subjects in computer vision. Stereovision is an attractive and widely used method, but, rather limited to make 3D surface maps, due to the correspondence problem. The correspondence problem can be improved using a method based on a structured light concept, projecting a given pattern on the measuring surfaces, although some relations between the projected pattern and the reflected one must be solved. This relationship can be directly found codifying the projected light, so that, each imaged region of the projected pattern carries the necessary information to solve the correspondence problem. We do not need to mention the numerous advantages in accurate obtention of 3D information for many research subjects, such as: robotics, autonomous navigation, shape analysis, and so on.

关键词： Layout Cameras Robot vision systems computer vision Information analysis robotics and automation Navigation Shape Light sources Image analysis

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