As software systems become more complex, the overall system structure---or software architecture---becomes a central design problem. A system's architecture provides a model of the system that suppresses implementation detail, allowing the architect to concentrate on the analyses and decisions that are most crucial to structuring the system to satisfy its requirements. Unfortunately, current representations of software architecture are informal and ad hoc. While architectural concepts are often embodied in infrastructure to support specific architectural styles and in the initial conceptualization of a system configuration, the lack of an explicit, independently-characterized architecture or architectural style significantly limits the benefits of software architectural design in current practice. In this dissertation, I show that an Architecture Description Language based on a formal, abstract model of system behavior can provide a practical means of describing and analyzing softwar...

As the design of software architectures emerges as a discipline within software engineering, it will become increasingly important to support architectural description and analysis with tools and environments. In this paper we describe a system for developing architectural design environments that exploit architectural styles to guide software architects in producing specific systems. The primary contributions of this research are: (a) a generic object model for representing architectural designs; (b) the characterization of architectural styles as specializations of this object model; and (c) a toolkit for creating an open architectural design environment from a description of a specific architectural style. We use our experience in implementing these concepts to illustrate how style-oriented architectural design raises new challenges for software support environments.

This paper describes Rogue, anintegrated planning and executing robotic agent. Rogue is designed to be aroving o ce gopher unit, doing tasks such as picking up & delivering mail and returning & picking up library books, in a setup where users can post tasks for the robot to do. We have been working towards the goal of building a completely autonomous agent which can learn from its experiences and improve uponits own behaviour with time. This paper describes what we have achieved to-date: (1) a system that can generate and execute plans for multiple interacting goals which arrive asynchronously and whose task structure is not known a priori, interrupting and suspending tasks when necessary, and (2) a system which can compensate for minor problems in its domain knowledge, monitoring execution to determine when actions did not achieve expected results, and replanning to correct failures. 1.

We present a terrain mapping system for walking robots that constructs quantitative models of surface geometry.

Our experience over the years with different architectures and planning systems for mobile robots has led us to a distributed approach where an arbiter receives votes for and against commands from each subsystem and decides upon the course of action which best satisfies the current goals and constraints of the system. Centralized arbitration of votes from distributed, independent decision-making processes provides coherent, rational, goal-directed behavior while preserving real-time responsiveness to its immediate physical environment. The Distributed Architecture for Mobile Navigation (DAMN) has been successfully used to integrate various independently developed subsystems, providing systems that perform road following, cross-country navigation, or teleoperation while avoiding obstacles and meeting mission objectives. Examples of implemented systems are given. Further research will seek to more rigorously define the behavior of the system. Keywords: mobile robots, architecture, behav...

khaigh�cs.cmu.edu

This thesis describes an approach to synthesizing plans for robotic excavators. Excavation tasks range from loading a pile of soil to cutting a geometrically described volume of earth--- for a trench or foundation footing. The excavation task can be stated in terms familiar to researchers in robotics and artificial intelligence: Transform the world from its current state to another state. Two important characteristics, however, distinguish the excavation domain. First, soil is deformable, and, hence, a complete state-space description of terrain to be excavated requires a high-dimensional representation. But, for the state-based representations that traditional planners use, very large spaces are simply infeasible. Second, the response of soil varies immensely, and in general, it is not possible to analytically describe the mechanics of soil motion and its interaction with tools. A soil's shear strength depends not only on its physical and chemical makeup, but also on factors such as t...

Intelligent behavior can be observed from both natural and artificial systems, but still the notion of intelligence is very difficult to define. We propose a new control architecture allowing the combination of reactivity, planning, deliberation and motives for building intelligent agents that must deal with real or other kinds of environments suited to their life purposes. This control architecture tries to unify the principles and characteristics associated with intelligence. It uses behaviors as its basic control components. These behaviors are selected dynamically and their actions are combined according to the intentions of the agent. Introspection of its reactions and its knowledge is one major new ability given to the agent by this architecture. This way, the agent is not only able to adapt to the environment, but also to its own capacities. One implementation for experimenting with a simulated environment for mobile robots is presented here to illustrate the use of this archite...

The mobile robot planning domain is dynamic, with goals becoming active asynchronously. In order to successfully operate in this environment, a robot must be able to interrupt and reformulate its plans of action on-the-fly. This paper investigates a method for incorporating the accomplishment of a new goal into a partially executed plan. A decision theoretic approach using net present value as the decision criterion serves as the basis for doing dynamic goal ordering. The appropriateness of net present value over benefit-cost ratio is argued. The approach has been implemented on a robot operating in an office setting. Examples from this domain are used to show the advantages of the approach with respect to fixed priority and heuristic based approaches. 1

We outline a multiple dimensional reference model architecture and a methodology for representing and developing intelligent systems. The reference model architecture features multiple dimensions enabling modeling the multiple aspects of complex systems. The canonical form within this framework facilitates an open and scalable system architecture. The well-defined structures facilitate efficient knowledge engineering processes. We describe a submarine automation model performing real-time control to illustrate the application of this reference model architecture. Keywords: automation, functional decomposition, hierarchical systems, intelligent control, methodology, multiple dimensional architecture, object oriented, task analysis.