A First Course in FUZZY and NEURAL CONTROL

4.4. FUZZY CONTROLLER DESIGN 155

position, and then begin to decrease the voltage as the error approaches zero.
There is some trial and error required here to achieve the ìbestî response.

As afirst step, let us make the membership function labeled ìZVî in the
motor-voltage set a bit narrower than the prototype chosen previously (see Fig-
ure 4.14).

Figure 4.14. Manual adjustment of membership function

Simulating the response now yields better performance than before, with
the rotor position nearly at the desired value of 1 radian in approximately 50
milliseconds. The full set of simulation results are shown in Figure 4.15.

Figure 4.15. Result of adjusting membership function

Since we require a slightly faster response (a settling time of 40 milliseconds),
we can make the ìZVî membership a bit narrower and try again. Suppose we
reshape the membership function as in Figure 4.16 and try simulating again.