Integral variable-structure grey control for magnetic levitation system

An integral variable-structure grey control for a magnetic levitation system for position tracking is presented. The sliding-mode control is insensitive to system uncertainties and disturbances when it is within expected limits. It produces chattering when uncertainty values are overestimated, or steady-state error when underestimated. The method uses a mathematically simple and computationally efficient grey compensator for the integral variable structure controller to reduce chattering and steady-state error. The stability of this magnetic levitation system is proven by using the Lyapunov function. The experimental results verify that the proposed controller is valid for a magnetic levitation system.