A Fuzzy Controller for Flakey, the Robot

Alessandro Saffiotti, Nicholas Helft, Kurt Konolige, John Lowrance, Karen Myers, Daniela Musto, Enrique Ruspini, Leonard Wesley

SRI International has a long tradition in the field of qualitative analysis and control of complex systems, starting with the development of the early mobile robot Shakey. More recently, we have developed a fuzzy controller for our new platform, Flakey. Flakey’s controller can pursue strategic goals while operating under conditions of uncertainty, incompleteness, and imprecision. This controller includes capabilities for: Robust, uncertainty-tolerating goal-directed activity. Real-time reactivity to unexpected contingencies (e.g., unknown obstacles). Blending of multiple goals (e.g., reaching a position while avoiding static and moving obstacles). In our approach, detailed in [2, 5], each goal is associated with a function that maps each perceived situation to a measure of desirability of possible actions from the point of view of that goal. The notion of a "control structure," is used for representing and manipulating high-level goals (and the associated desirability functions) in the fuzzy controller. Typical control structures are associated with environment features such as locations to reach, walls, or doorways. Each desirability function induces a particular "behavior" -one obtained by executing the actions with higher desirability. Many behaviors, induced by many simultaneous goals can be smoothly blended together by combining their desirability functions using the inferential procedures of fuzzy logic. The fuzzy controller prefers the actions that best satisfy each behavior. Blending of behaviors is the key to combining goal-oriented activity (e.g., trying to reach a given location) and reactivity (e.g., avoiding obstacles on the way).

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