A frequently discussed issue in the use of fuzzy systems for control d
esign is related to the ad hoc nature by which controller synthesis is
performed, where incorporation of the designer's knowledge into the s
ynthesis procedure is often not straightforward. This paper describes
a controller synthesis procedure based on the idea of expanding the us
able region of a linear control design technique. Comparative analyses
are carried out via implementation of swing-up and balancing control
for a rotational inverted pendulum system. For the complete control pr
oblem, the paper focuses on three aspects of fuzzy control in the over
all control design: direct, supervisory, and auto-tuning fuzzy control
. For swing-up control, an energy pumping strategy, enhanced by introd
ucing a fuzzy supervisory mechanism, is utilized. For balancing contro
l, an LQR-based linear control strategy, valid in the ''linear region'
' of operation of the pendulum, is generalized to a nonlinear direct f
uzzy control design. For improved performance when modeling uncertaint
ies affect controller performance, a new scheme is developed, again ba
sed on the LQR design, which is a simple yet effective auto-tuned fuzz
y controller, having the capability to vary its resolution on-line. Al
l controllers are tested on an experimental apparatus, and performance
comparisons are drawn.