In the design of a control system w:ith structural uncertainties, parameter perturbations and environmental disturbances, designers normally try to minimise the use of a detailed mathematical model whose ambiguities can never be modelled accurately. One suitable approach for this kind of nonlinear controller designs, avoiding the use of complicated models, is to employ variable structure system theory, which has been successfully applied to a wide variety of systems having uncertainties in the representative system model. In meeting the specifications of the closed loop system, those conventional controller design strategies usually fail to achieve the desired characteristics. In order to upgrade the performance of the controller and facilitate the design procedure, one should integrate artificial intelligence, most likely from expert linguistic knowledge, with conventional control algorithms.