Adaptive control of a voltage-controlled magnetic levitation system with K-filter

This paper deals with the complex position tracking control problem of magnetic levitation system with parameter uncertainty and external disturbance. This system has openloop instability and non-linearity in electromechanical system. The system dynamics is controlled by a third-order nonlinear differential equation, which consists of the position error subsystem, the mechanical error subsystem and the electrical error subsystem. The position and current state variables can be measured in real time, while the velocity state variables cannot be measured. First, the unmeasurable velocity state variable is observed through K-filter. Second, combined with adaptive control technology, backstepping method is adopted to design the overall controller of the system. Third, by using Lyapunov function, the stability of the whole nonlinear control system is proved. Then the stability of the system is analyzed strictly. The simulation experimental results show that the designed controller has good tracking performance for the complex reference trajectory.