Intelligent Computation of the Equivalent Control in Sliding Mode for Nonlinear Motion Systems

Abstract

Conventional control theory is well suited for application where the control efforts can be generated based on analytical model. Sliding mode control (SMC), based on the theory of variable structure systems (VSS), has been widely applied to nonlinear motion control. Hence it is practically difficult to implement these algorithms when the parameters of the system are not precisely known in advance or the system is subjected to unmodelled nonlinearities and uncertain disturbance. In consequence, it is much more difficult to find a solution for this problem. In the application of sliding mode controllers, the main problem which is encountered is that a whole knowledge of the system dynamics and the system parameters is required to be able to compute the equivalent control. In this paper, we consider adding some computationally methods to the SMC by automatically tuning the control parameters. This approach retains the property of SMC but alleviates the chattering, and the intelligent control parameters can be determined systematically by the reaching condition of the SMC. And the method of designing intelligent controller is achieved automatically without domain experts. Simulation results of a two-dimensional inverted pendulum confirm that the effect of both the fuzzy approximation error and external disturbance on the tracking error can be attenuated efficiently by the proposed method.