A Fuzzy Behaviorist Approach to Sensor-Based Robot Control

Sensor-based operation of autonomous robots in unstructured and/or outdoor environments has revealed to be an extremely challenging problem. mainly because of the difficulties encountered when attempting to represent the many uncertainties which are always present in the real world. These uncertainties are primarily due to sensor imprecisions and unpredictability of the environment. i.e., lack of full knowledge of the environment characteristics and dynamics. An approach. which we have named the "Fuzzy Behaviorist Approach" (FBA) is proposed in an attempt to remedy some of these difficulties. This approach is based on the representation of the system's uncertainties using Fuzzy Set Theory-based approximations and on the representation of the reasoning and control schemes as sets of elemental behaviors. Using the FBA, a formalism for rule base development and an automated generator of fuzzy rules have been developed. This automated system can automaticall) construct the set of membership functions corresponding to fuzzy behaviors. once these have been expressed in qualitative terms by the user. The system also checks for completeness of the rule base and for non-redundancy of the rules (which has traditionall) been a major hurdle in rule base development). Two major conceptual features. the suppression and inhibition mechanisms which allow to express a dominance between behaviors are discussed in detail. Some experimental results obtained with the automated fuzzy rule generator applied to the domain of sensor-based navigation in a priori unknotrn environments. using one of our autonomous test-bed robots as well as a real car in outdoor environments. are then reviewed and discussed to illustrate the feasibilit) of large-scalc automatic fuzq rule generation using the "Fuzzy Behaviorist" concepts.