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Publications

Publications by CRAS

1997

On the design of a hybrid feedback control system for a nonholonomic car-like vehicle

Authors
Almeida, J; Pereira, FL; Sousa, JB;

Publication
ECC 1997 - European Control Conference

Abstract
This paper addresses the design of a hybrid feedback control system enabling a car-like, rectangular vehicle to perform a tight L-shaped turn maneuver. This case constitutes an effort towards the definition of a general purpose methodology for hybrid feedback control synthesis. The design effort encompasses the synthesis of a set of modalities and mechanisms to detect relevant events enabling the overall motion coordination so that a global goal is attempted. Simulations of the implemented controller have shown a strong robustness with respect to modeling uncertainty and execution errors.

1997

Environmental decision support

Authors
Malheiro, B; Oliveira, E;

Publication
Proceedings of the first international conference on Autonomous agents - AGENTS '97

Abstract

1997

Environmental decision support: A multi-agent approach

Authors
Malheiro, B; Oliveira, E;

Publication
Proceedings of the Interantional Conference on Autonomous Agents

Abstract
The environmental management domain is vast and encompasses many identifiable activities: impact assessment, planning, project evaluation, etc. In particular, this paper focusses on the modelling of the project evaluation activity. The environmental decision support system under development aims to provide assistance to project developers in the selection of adequate locations, guaranteeing the compliance with the applicable regulations and the existing development plans as well as satisfying the specified project requirements. The inherent multidisciplinarity features of this activity lead to the adoption of the Multi-Agent paradigm, and, in particular, to the modelling of the involved agencies as a community of cooperative autonomous agents, where each agency contributes with its share of problem solving to the final system's recommendation. To achieve this behaviour the many conclusions of the individual agencies have to be justifiably accommodated: not only they may differ, but can be interdependent, complementary, irreconcilable, or simply, independent. We propose different solutions (involving both local and global consistency) to support the adequate merge of the distinct perspectives that inevitably arise during this type of decision making.

1996

A simulated annealing approach for high-level synthesis with reconfigurable functional units

Authors
Alves, JC; Matos, JS;

Publication
38TH MIDWEST SYMPOSIUM ON CIRCUITS AND SYSTEMS, PROCEEDINGS, VOLS 1 AND 2

Abstract
In this paper, we present an application of the simulation annealing optimization algorithm to the problem of high-level synthesis of digital systems, targeted to architectures with run-time reconfigurable functional units. The scheduling, allocation and binding problems are treated simultaneously. Reconfiguration times and execution delays are taken into account, along with pipelined execution and precise clock cycles for consumption of each operand.

1996

On the design and implementation of a control architecture for a mobile robotic system

Authors
Sousa, JB; Pereira, FL; daSilva, EP; Martins, A; Matos, A; Almeida, J; Cruz, N; Tunes, R; Cunha, S;

Publication
1996 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND AUTOMATION, PROCEEDINGS, VOLS 1-4

Abstract
In this article, we describe the analysis, design and implementation of a control architecture for a mobile platform to autonomously carry out transportation, surveillance and inspection tasks in semi-structured industrial environments. Based on a hierarchical structure composed by the Organization, Coordination and Functional levels organized linguistically and structured according to the Principle of Increasing Precision with Decreasing Intelligence, this control architecture is permits the real-time parallel execution of tasks.

1996

A general control architecture for multiple AUVs

Authors
Sousa, JB; Pereira, FL; daSilva, EP;

Publication
PROCEEDINGS OF THE 1996 SYMPOSIUM ON AUTONOMOUS UNDERWATER VEHICLE TECHNOLOGY

Abstract
This paper presents a conceptual architecture for the control of multiple autonomous underwater vehicles based on the concept of Generalized Vehicle. The design of this architecture was driven by requirements extracted from the analysis of operational scenarios involving the operation of multiple vehicles and embodies an extension of the Dynamically Reconfigurable Control Architecture for an AUV proposed by the authors in previous published work.

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