Computer - Aided Design of a Generic Robot Controller HandlingReactivity and Real - Time Control

This paper describes an original system, Orccad, for the computer-aided design of robot controllers. Accessed by three diierent user levels (system, control and application), it proposes a coherent approach from a high level speciication down to its implementation, and ooers several tools for design, display and test. Following a critical study of the main architectures reported through the literature, the paper presents the basic principles and underlying concepts of Orccad. The main entity considered is the robot task, an elementary control action associated with a local behavior controlled by a set of observers and modeled by a nite state automaton. It is made of a set of real-time communicating tasks, called module tasks, the full deenition of which requires the speciication of temporal and synchronization features. The module task which handles the behavior of the robot task is described using the synchronous language Esterel. The application level is deened as a set of synchronized robot tasks, also described using Esterel. Two detailed examples are discussed. The rst one consists in the speciication and the test of a few versions of a joint control for a rigid robot; the other one is a mission speciication for an autonomous underwater vehicle. Dialogue and veriication tools are integrated within Orccad: a graphical Human-Machine Interface used to build the Robot-Tasks and a simulation software dedicated to hybrid continuous/discrete time simulations. 1 0 Part of this work is made in cooperation with Aleph Technologies, Grenoble, France with support from Ministtre de la Recherche et de l'Espace under grant #91 S 0097. A long version of this paper is available as Inria research report #1801 ((38])