A Visual Environment for Rapid Behavior Definition

We describe a visual framework that simplifies authoring of simulated behavior. This framework consists of a canvas depicting behavior as a finite state machine (FSM) graph, a palette of geometric objects and glyphs, and a dictionary of actions and predicates. The user defines a basic vocabulary of actions and predicates which appear as textual and geometric shapes on the canvas. The actions correspond to states in an FSM. Predicates are used to determine valid transitions between states. The basic model is extended in two major ways. First, behaviors are hierarchical in that they may invoke each other. Second, each behavior may have a number of specializations indexed through a descriptor hierarchy. These two extensions serve to encapsulate functionality, and to selectively specialize behavior whenever necessary without arduous re-modification of existing behavior.