25. A method as recited in claim 23 wherein the first and second sensed linguistic variables and associated membership function sets correspond to the guidance point error signal and rate of change error signal respectively and each has a fixed plurality of linguistic variables and associated membership functions corresponding to different values of the corresponding sensed linguistic variables, each of said sensed variable membership functions being programmable to vary a classification of a particular value of a sensed variable signal, said sensed variable membership functions being overlapped whereby the classification of certain values of a sensed variable signal produce a selection of plural sensed linguistic variables.
26. A method as recited in claim 25 wherein said selection of a control output linguistic variable and associated membership function is made according to a predetermined number of logical rules based upon selected individual sensed linguistic variables.