Patent Document ID: 20020138187
Application ID: 09781019
Patent Flag: 0

Claim One:
1. A steering controller for a wheeled work vehicle having a hydraulic actuator coupled to steerable wheels on the vehicle and driven by a proportional control electrohydraulic valve, a sensor that generates a signal indicative of the degree of turning of the wheels and the actual position of the wheels, the controller comprising: a first fuzzifying circuit configured to convert a single real-valued turning rate signal into a first set of two values indicative of membership in two fuzzy sets; a second fuzzifying circuit configured to convert a single real-valued turning position error signal into a second set of two values indicative of membership in two fuzzy sets; a fuzzy rule base including a plurality of rules to convert the first and second sets of values into a third set of values indicating membership in two or more fuzzy steering command sets; a fuzzy inference engine configured to apply the plurality of rules to the first and second sets and derive the third set of values; and a defuzzifying circuit configured to combine the third set of values into a single real-valued steering command indicative of the degree of opening of the proportional control electrohydraulic valve.