J. Borges de Sousa

A simulation environment for the coordinated operation of multiple autonomous underwater vehicles

A simulation environment of the coordinated operation of multiple Autonomous Underwater Vehicles (AUVs) is presented. The primary application of this simulation environment is the specification and analysis of an innovative approach to coastal oceanography based on the Generalized Vehicle [GV] concept. A Generalized Vehicle is a group of vehicles whose spatial and logic organization is coordinated in such a way that the group behaves as a single entity. The simulation environment was developed in Shift, a new specification language for describing dynamic networks of hybrid automata. These constitute the most adequate modeling formalism for this problem domain. The expressive power of Shift provides a compact notation for modeling spatial and logical relationships in a dynamic environment and for modeling and analyzing control strategies governing object interactions.

Coordinated Control of Networked Vehicles: An Autonomous Underwater System

The specification and design of coordinated control strategies for networked vehicle systems are discussed. The discussion is illustrated with an example of the coordinated operation of two teams of autonomous underwater vehicles collecting data to find the local minimum of a given oceanographic scalar field.The specification and design of coordinated control strategies for networked vehicle systems are discussed. The discussion is illustrated with an example of the coordinated operation of two teams of autonomous underwater vehicles collecting data to find the local minimum of a given oceanographic scalar field.

ON THE DESIGN OF A CONTROL ARCHITECTURE FOR AN AUTONOMOUS MOBILE ROBOT

In this chapter we present a model of a hierarchic control architecture for Autonomous Mobile Robots (AMR) as well as its use in the design of an autonomous wheeled mobile platform for transportation in an industrial environment. This model results from successive incremental refinements consolidated over the years with the experience accumulated in a number of R&D projects (e.g., [1], [2]) with special emphasis for the NATO funded PO-Robot project [3].

A dynamically configurable architecture for the control of autonomous underwater vehicles

This paper presents a control architecture for autonomous underwater vehicles AUVs. The proposed architecture has its foundations on a hierarchic structure organized linguistically where parallel operations take place in real-time. this hierarchic structure is composed of three levels: organization, coordination and functional layer, structured according to the principle of increasing precision with decreasing intelligence. The main contribution is the concept of dynamically configurable architecture where the notion of architecture coordinator plays a crucial role. This system dynamically configures the connections among modules of the functional and maintains the state of this configuration so that the most adequate translation of planned actions into execution commands takes place. These coordination features are also used to incorporate the emergence of reactive behaviours in this hierarchic architecture. >This paper presents a control architecture for autonomous underwater vehicles AUVs. The proposed architecture has its foundations on a hierarchic structure organized linguistically where parallel operations take place in real-time. this hierarchic structure is composed of three levels: organization, coordination and functional layer, structured according to the principle of increasing precision with decreasing intelligence. The main contribution is the concept of dynamically configurable architecture where the notion of architecture coordinator plays a crucial role. This system dynamically configures the connections among modules of the functional and maintains the state of this configuration so that the most adequate translation of planned actions into execution commands takes place. These coordination features are also used to incorporate the emergence of reactive behaviours in this hierarchic architecture.<<ETX>>

On the receding horizon hierarchical optimal control of manufacturing systems

This paper concerns the development of a hierarchical framework for the integrated planning and scheduling of a class of manufacturing systems. In this framework, dynamic optimization plays an important role in order to define control strategies that, by taking into account the dynamic nature of these systems, minimize customized cost functionals subject to state and control constraints. The proposed architecture is composed of a set of hierarchical levels where a two-way information flow, assuming the form of a state feedback control, is obtained through a receding horizon control scheme. The averaging effect of the receding horizon control scheme enables this deterministic approach to handle random and unexpected events at all levels of the hierarchy. At a given level, production targets to the subsystems immediately below are defined by solving appropriate optimal control problems. Efficient iterative algorithms based on optimality conditions are used to yield control strategies in the form of production rates for the various subsystems. At the lower level, this control strategy is further refined in such a way that all sequences of operations are fully specified. The minimum cost sensitivity information provided in the optimal control formulation supports a mechanism, based on the notion of a critical machine, which plays an important role in the exploitation of the available flexibility. Finally, an important point to note is that our approach is particularly suited to further integration of the production system into a larger supply chain management framework, which is well supported by recent developments in hybrid systems theory.

A general control architecture for multiple vehicles

This paper presents a general architecture for the control of multiple vehicles based on the concept of generalized vehicle. This embodies an extension of the dynamically reconfigurable control architecture previously proposed by the authors (1994, 1995). Besides the capabilities of each vehicle inherent to the individual autonomy, the set of vehicles may be seen providing a pool of functionalists whose reconfiguration enables the emergence of a global features overcoming the single vehicle limitations. Unlike some other approaches, cooperation does not take place only at a deliberative level, but it results from a global coordination level implemented via an adequate protocol specified in the the global mission plan. The design of this architecture was driven by requirements extracted from the analysis of operational scenarios involving multiple vehicles.This paper presents a general architecture for the control of multiple vehicles based on the concept of generalized vehicle. This embodies an extension of the dynamically reconfigurable control architecture previously proposed by the authors (1994, 1995). Besides the capabilities of each vehicle inherent to the individual autonomy, the set of vehicles may be seen providing a pool of functionalists whose reconfiguration enables the emergence of a global features overcoming the single vehicle limitations. Unlike some other approaches, cooperation does not take place only at a deliberative level, but it results from a global coordination level implemented via an adequate protocol specified in the the global mission plan. The design of this architecture was driven by requirements extracted from the analysis of operational scenarios involving multiple vehicles.

Coordination Challenges in Networked Vehicle Systems: Are We Missing Something?

The computation and control challenges arising in the coordination of multi-vehicle systems are discussed in the framework of (coupled) physical and computational dynamics. The challenges are formulated as classical control problems of optimization, invariance, and attainability for systems governed by the laws of physics and computation. Directions for future research are discussed with special emphasis on the aspects of coupled dynamics and dynamic structure that seem to be missing in the literature.

AUV system requirements for coastal oceanography

Classes of oceanographic missions addressing relevant distinct scientific and applied objectives in the Portuguese coastal waters are examined in the context of an R&D project aiming at providing a methodological framework adapted to the specific requirements of AUV-based systems design. Preliminary results consisting on the mapping of requirements onto a modular system are presented.Classes of oceanographic missions addressing relevant distinct scientific and applied objectives in the Portuguese coastal waters are examined in the context of an R&D project aiming at providing a methodological framework adapted to the specific requirements of AUV-based systems design. Preliminary results consisting on the mapping of requirements onto a modular system are presented.

A dynamically configurable control architecture for autonomous mobile robots

This paper presents a dynamically configurable architecture for the control of autonomous mobile robots based on hierarchic structure whose three levels, organization, coordination and functional layer, are organized linguistically. The main contribution is the concept of dynamic reconfigurability where the notion of architecture coordinator plays a crucial role. The design of the functional layer establishes the primitives for dynamic configuration.This paper presents a dynamically configurable architecture for the control of autonomous mobile robots based on hierarchic structure whose three levels, organization, coordination and functional layer, are organized linguistically. The main contribution is the concept of dynamic reconfigurability where the notion of architecture coordinator plays a crucial role. The design of the functional layer establishes the primitives for dynamic configuration.

A Model Predictive Control Approach to AUVs Motion Coordination

The problem of coordinating the motion of autonomous underwater vehicles under constrained acoustic communications is formulated and investigated in the context of the model predictive control (MPC) framework. The impact of acoustic communications and perturbations on the motion performance and robustness is discussed. A reach set formulation of the MPC scheme is outlined.