AN ARCHITECTURE FOR AUTONOMY

An autonomous robot offers a challenging and ideal field for the study of intelligent architectures. Autonomy within a rational behavior cou ld be evaluated by the robot's effectiveness and robustness in carryin g out tasks in different and ill-known environments. It raises major r equirements on the control architecture. Furthermore, a robot as a pro grammable machine brings up other architectural needs, such as the eas e and quality of its specification and programming. This article descr ibes an integrated architecture that allows a mobile robot to plan its tasks-taking into account temporal and domain constraints, to perform corresponding actions and to control their execution in real-time-whi le being reactive to possible events. The general architecture is comp osed of three levels: a decision level, an execution level, and a func tional level. The latter is composed of modules that embed the functio ns achieving sensor-data processing and effector control. The decision level is goal and event driven, and it may have several layers, accor ding to the application; their basic structure is a planner/supervisor pair that enables the architecture to integrate deliberation and reac tion. The proposed architecture relies naturally on several representa tions, programming paradigms, and processing approaches, which meet th e precise requirements that are specified for each level. The authors have developed proper tools To meet these specifications and implement each level of the architecture: a temporal planner IxTeT; a procedura l system for task refinement and supervision, PRS; Kheops for the reac tive control of the functional level, and G(en)oM for the specificatio n and integration of modules at that level. Validation of the temporal and logical properties of the reactive parts of the system, through t hese tools, are presented. Instances of the proposed architecture have been integrated into several indoor and outdoor robots. Examples from real-world experimentations are provided and analyzed.