Gravitational Search Algorithms in Fuzzy Control Systems Tuning

This paper suggests the use of Gravitational Search Algorithms (GSAs) in fuzzy control systems tuning. New GSAs are first offered on the basis of the modification of the depreciation equation of the gravitational constant with the iteration index and of an additional constraint regarding system’s overshoot. The GSAs are next used in solving the optimization problems which minimize the discretetime objective functions defined as the weighted sum of the squared control error and of the squared output sensitivity functions. The sensitivity functions are derived from the sensitivity models defined with respect to the parametric variations of the controlled plant such that to aim the parametric sensitivity reduction. The presentation focuses the representative case of Takagi-Sugeno PI-fuzzy controllers (PIFCs) that controls a class of servo systems characterized by second-order linearized models with integral component. Discussions concerning the tuning of the PI-FC parameters in a case study are included.