COTAMA, a control software architecture for contextual task management

This paper describes COTAMA (COntextual TAsk Management Architecture), a control software architecture layered into tow levels: Decisional level and executive level. The decisional level is in charge of mission monitoring and decision making according to robot context. The executive level applies these decisions while managing all real time aspects such instrumentation conflicts or tasks deadlines. The whole architecture is built on a set of entities called modules. Each module implement a function like control law computing or sensor management. Data are exchanged between modules through ports. The decisional level modules work in an asynchronous way by reacting to low level events. The executive modules are managed by a scheduler. This scheduler brings under control all executive level modules activities. By tacking into account, all time constraints related to tasks deadlines and instrumentation conflicts, this scheduler is able to activate executive modules in the appropriate sequence to avoid conflicts and to respect deadlines.