Planning and reasoning with processes

The motivation and design behind the planning system called EXCALIBUR are described. EXCALIBUR is a planning system which successfully integrates planning and execution within a common control strategy. EXCALIBUR combines a Nonlin-like planner with an execution monitor based on qualitative process theory. The implementation fully integrates information from the planner and the model and does not simply view the model as a `bolt-on´ extra. This architecture gives EXCALIBUR the ability to follow the execution of a plan and if necessary replan when failures occur during execution. The author describes how the planner functions, the types of plans which it can handle and the current limitations