Controller Design for Multivariable Nonlinear Control Systems Based on Multi Objective Evolutionary Techniques

While Single Input Describing function is a suitable linearization technique in the frequency domain for assessment of stability and limit cycle operation, it can not be employed in time domain. In order to be able to incorporate the time domain requirements in an overall controller design technique, the appropriate linearization techniques suggested here is the Exponential Input Describing Function (EIDF)[4]. In this method we assume that inputs to the nonlinear elements are Exponential in form. On the basis of this assumption the nonlinear element may then be replaced by the equivalent EIDF gain. Experimental results obtained thus far show that Evolutionary multi objective optimization technique developed here for controller design of nonlinear multivariable feedback control systems is capable producing optimal and practical controllers that meet the design requirement in an efficient manner and computationally acceptable amount of time.

Keywords:

Nonlinear Control , Multi Objective Evolutionary Algorithms , EIDF