20. A method as recited in claim 19 wherein said selection of sensed linguistic variables includes using the sensed bearings and sets of sensed variable membership functions for selecting the sensed linguistic variables and wherein said generation of said guidance command includes using the selected control output linguistic variables to select corresponding control output membership functions and combining the selected control output membership functions to produce a control output.
31. A method as recited in claim 20 wherein said guidance command generating step includes the step of testing the guidance command against predetermined limits thereby to constrain the guidance command.