An Integral Variable Continuous Exponential Reaching Law PD Sliding Mode Control of Magnetic Levitation System

Magnetic Levitation System (MLS) is a complex nonlinear control system. The aim of MLS control is to keep the vertical position of a metal ball by adjusting the duty ratio of electromagnet voltage. Sliding mode controller achieves the robustness to unknown disturbance and uncertainty, however, its control variable chattering is an obstacle for applications. There are some traditional methods to reduce the chattering at the cost of increasing the steady state error. In this paper, we present an improved reaching law based on proportional-derivative (PD) sliding surface to reduce the chattering, at the same time, to reduce steady-state error. The simulation is performed to test the effectiveness of the proposed method. The proposed method is compared with four other controllers to show the superiority.