¹Department of Electrical & Computer Engineering Polytechnic University of Puerto Rico, San Juan, Puerto Rico, USA
²School of Computing & Informatics The Nottingham Trent University Nottingham, UK
³Hong Kong Baptist University, Kowloon, Hong Kong

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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

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Cite: F. C. TENG, A. LOTFI, A. C. TSOI, "Novel Fuzzy Logic Controllers with Self-Tuning Capability," Journal of Computers vol. 3, no. 11, pp. 9-16 , 2008.