JOURNAL OF COMPUTERS (JCP)
ISSN : 1796-203X
Volume : 3    Issue : 11    Date : November 2008

Novel Fuzzy Logic Controllers with Self-Tuning Capability
Fong Chwee Teng,  Ahmad Lotfi, and Ah Chung Tsoi   
Page(s): 9-16
Full Text:
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Abstract
Two controllers which extend the PD+I fuzzy logic controller to deal with the plant having time varying
nonlinear dynamics are proposed. The adaptation ability of the first self tuning PD+I fuzzy logic
controller (STPD+I_31) is achieved by adjusting the output scaling factor automatically thereby
contributing to significant improvement in performance. Second controller (STPD+I_9) is the
simplified version of STPD+I_31 which is designed under the imposed constraint that allows only
minimum number of rules in the rule bases. The proposed controllers are compared with two
classical nonlinear controllers: the pole placement self tuning PID controller and sliding mode
controller. All the controllers are applied to the two-links revolute robot for the tracking control. The
tracking performance of STPD+I_31 and STPD+I_9 are much better than the pole placement self
tuning PID controller during high speed motions while the performance are comparable at low and
medium speed. In addition, STPD+I_31 and STPD+I_9 outperform sliding mode controller using
same method of comparison study.

Index Terms
Self-tuning PD+I fuzzy logic control, output scaling factor, self tuning pole placement PID control,
sliding mode control, two-links revolute robot, minimum number of rules.