Variable structure control of nonlinear system using fuzzy variable boundary layer

We suggest a variable structure controller based on a fuzzy variable boundary layer with control gain and boundary layer thickness as design parameters. Control gain is an important factor affecting the control performance of the variable structure system (VSS). The sliding mode controller based on a variable boundary layer is superior to the fixed-layer method for tracking characteristics. In order to regulate the design parameters and increase the operating efficiency, the scheme makes use of a fuzzy inference which reduces the number of fuzzy inputs. By using fuzzy algorithms in choosing control gain and boundary layer, we propose methods which have better tracking performance than the conventional method. To demonstrate the advantages of the proposed algorithm, it is applied to a nonlinear system.