物件導向軟體之架構(Object-Oriented Software Construction)探討

Vehicular networking has significant potential to enable diverse applications associated with traffic safety, traffic efficiency and infotainment. In this survey and tutorial paper we introduce the basic characteristics of vehicular networks, provide an overview of applications and associated requirements, along with challenges and their proposed solutions. In addition, we provide an overview of the current and past major ITS programs and projects in the USA, Japan and Europe. Moreover, vehicular networking architectures and protocol suites employed in such programs and projects in USA, Japan and Europe are discussed.

Vehicular Networking: A Survey and Tutorial on Requirements, Architectures, Challenges, Standards and Solutions

“Multivalued Analysis” is the theory of set-valued maps (called multifonctions) and has important applications in many different areas. Multivalued analysis is a remarkable mixture of many different parts of mathematics such as point-set topology, measure theory and nonlinear functional analysis. It is also closely related to “Nonsmooth Analysis” (Chapter 5) and in fact one of the main motivations behind the development of the theory, was in order to provide necessary analytical tools for the study of problems in nonsmooth analysis. It is not a coincidence that the development of the two fields coincide chronologically and follow parallel paths. Today multivalued analysis is a mature mathematical field with its own methods, techniques and applications that range from social and economic sciences to biological sciences and engineering. There is no doubt that a modern treatise on “Nonlinear Functional Analysis” can not afford the luxury of ignoring multivalued analysis. The omission of the theory of multifunctions will drastically limit the possible applications.

SET-Valued Analysis

Inspired by the so-called "bugs" problem from mathematics, we study the geometric formations of multivehicle systems under cyclic pursuit. First, we introduce the notion of cyclic pursuit by examining a system of identical linear agents in the plane. This idea is then extended to a system of wheeled vehicles, each subject to a single nonholonomic constraint (i.e., unicycles), which is the principal focus of this paper. The pursuit framework is particularly simple in that the n identical vehicles are ordered such that vehicle i pursues vehicle i+1 modulo n. In this paper, we assume each vehicle has the same constant forward speed. We show that the system's equilibrium formations are generalized regular polygons and it is exposed how the multivehicle system's global behavior can be shaped through appropriate controller gain assignments. We then study the local stability of these equilibrium polygons, revealing which formations are stable and which are not.

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Formations of vehicles in cyclic pursuit

Inter-vehicle communication (IVC) protocols have the potential to increase the safety, efficiency, and convenience of transportation systems involving planes, trains, automobiles, and robots. The applications targeted include peer-to-peer networks for web surfing, coordinated braking, runway incursion prevention, adaptive traffic control, vehicle formations, and many others. The diversity of the applications and their potential communication protocols has challenged a systematic literature survey. We apply a classification technique to IVC applications to provide a taxonomy for detailed study of their communication requirements. The applications are divided into type classes which share common communication organization and performance requirements. IVC protocols are surveyed separately and their fundamental characteristics are revealed. The protocol characteristics are then used to determine the relevance of specific protocols to specific types of IVC applications.

A survey of inter-vehicle communication protocols and their applications

In this paper, we propose a hierarchical control architecture for an enhanced variant of Cooperative Adaptive Cruise Control (CACC), which would include some Cooperative Forward Collision Warning (CFCW) functionality. Simply put, a CACC system is a more sophisticated variant of cruise control. By a control architecture we mean a specific way of organizing the motion control and navigation functions performed by the cars. It is convenient to organize the functions into hierarchical layers. This way, a complex design problem is partitioned into a number of more manageable sub-problems that are addressed in separate layers. This paper discusses vehicle control requirements and maps them onto a layered control architecture. The formalization of the hierarchy is accomplished in terms of the specific functions accomplished by each layer and of the interfaces between layers. The implementation of the layers is discussed and illustrative examples are provided.

A control architecture for integrated cooperative cruise control and collision warning systems

Autonomous vehicle systems have been the topic of much research due to their ability to perform dangerous, repetitive and automated tasks in remote or hazardous environments. The potential for multi-vehicle systems cooperating together to accomplish given tasks is starting to draw together researchers from several fields, including robotics, control systems, and computer science. Multiple vehicles can be more effective than a single one, for example in information gathering tasks. By spreading out over the terrain to be searched, a cluster of autonomous helicopters, for example, can locate a target quite rapidly, or a group of coordinated autonomous underwater vehicles can search a coastal area for mines. In other cases, the coordinated operation of multiple vehicles can provide new capabilities. This is the case, for example, of the PATH strategy of platooning several vehicles as they travel along the highway, which may yield up to a four-fold increase in transportation capacity while enhancing safety. Another example is the Mobile Offshore Base, where semi-submersible modules are aligned to form a military base and runway at sea. The unprecedented length of the at-sea runway (up to a mile long) warrants the use of several modules. In each of these cases, there is a need for inter-vehicle communications so that each vehicle can know the status of the operation, the position of its counterparts, and whether the specific mission goals have changed. Thus the control and communication problems become inexorably tied. However, few results are available to analyze performance and stability of a closed loop system where some of the loops are closed by communicated variables. Using the above examples as a motivation, this paper examines emerging results in networked multi-vehicle systems. Recent work has taken many different approaches, such as hybrid systems, distributed control, differential games, control architectures, and artificial intelligence. The focus of this paper is on the control systems perspective. We attempt to present some current issues common to networked multi-vehicle systems, and to show how they have been solved to date in the perspective of the case studies.

An overview of emerging results in networked multi-vehicle systems

The rich and exciting research over the past decade concerning the description, analysis, controller design, simulation, and implementation of distributed systems is reviewed. From control engineering, this research has inherited the concepts and theories of optimality, stability, controlled differential equation models, and the motivation to improve the performance of increasingly complex physical processes. From computer science, the research has incorporated the theories of logical specification and verification, event-driven state machine models, concurrent processes and object-oriented approaches. The review is organized in the framework of dynamic networks of hybrid automata. The case study of an automated highway system is used to illustrate the challenges posed by a complex distributed system, and the research contributions that address different challenges. There is an equal emphasis on the conceptual and theoretical contributions and on tools and techniques that yield more immediately practical benefits.

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Communication and control of distributed hybrid systems

The real-time hybrid control of mobile offshore base scaled models is considered. The mobile offshore base is a large, self-propelled, floating, pre-positioned ocean structure formed of three to five modules and reaching up to 1,500 meters in length. The system requirements are quite complex since the roles, relative positions and dependencies of the modules may change during operation, and the system is hybrid (it contains both continuous activities and discrete event features). We describe the experiment in which three scaled modules are kept aligned by pivoting thrusters and form a miniature runway. The software design for the experiment is discussed, starting with the three-layered control architecture, the software architecture and layout for the experiments, and the real-time implementation. Preliminary results are presented and discussed.

Real-time hybrid control of mobile offshore base scaled models

The REP10 AUV experiment, which took place in Portugal, is described together with the lessons learned with this deployment. The REP10 AUV experiment was organized by the Portuguese Navy in cooperation with the Naval Undersea Warfare Center - Newport (US), Porto University (PO), the Naval Research Laboratory (US) and the NATO Undersea Research Centre (IT). The experiment was focused on the demonstration of heterogeneous autonomous vehicles in mine-warfare and Rapid Environmental Assessment missions. Nine autonomous submarines of 4 different types (Gavia, Iver2, LAUV SeaCon and Isurus) were deployed together with the autonomous catamaran Swordfish from the Bacamarte ship from the Portuguese Navy. Spatial and temporal segregation principles simplified the deployment of multiple vehicles from different institutions. Inter-operated wireless and acoustic networks were used to demonstrate the feasibility of real-time task re-planning and situational awareness. The surface autonomous vehicle proved key to the deployment of additional sonars and communication gateways. Remote servers were used for data assimilation and forecasting for daily planning.

J.B. de Sousa

Papers

A control architecture for integrated cooperative cruise control and collision warning systems

An overview of emerging results in networked multi-vehicle systems

Communication and control of distributed hybrid systems

Real-time hybrid control of mobile offshore base scaled models

REP10 AUV: Shallow water operations with heterogeneous autonomous vehicles