Ella M. Atkins, Edmund H. Durfee, Kang G. Shin
Complex plans are required to safely operate an autonomous system in a dynamic environment. An ideal planner would build all reactions offline so it could deliberate as long as necessary to develop its response set. However, it may be impossible to build and store all plans offline, so online planning is required whenever previously unplanned-for situations arise. In a dynamic system, online planning must be terminated within time bounds imposed by the environment, with potentially adverse affects on plan quality. We propose that the primary goal of any system is to avoid failure (e.g., system destruction), and a secondary consideration is to achieve other goals. In this abstract, we propose a method to balance offline vs. online planning in terms of failure avoidance. We combine pre-planned responses with time-bounded online planning in CIRCA, the Cooperative Intelligent Real-time Control Architecture (Musliner, Durfee, and Shin 1993), shown in Figure 1. CIRCA combines a planner, scheduler, and real-time plan execution subsystem (RTS) to allow guaranteed performance for critical responses. We have augmented CIRCA to allow contingency plan storage via a Plan Dispatcher module and a small but quickly-accessed cache within the RTS.