Robust Sliding Mode Control of a Planar Rigid Rotor System on Magnetic Bearings

A planar rigid rotor supported on magnetic bearings is controlled using a robust sliding mode controller. Linearized magnetic bearings and mass unbalance are considered. A nonlinear sliding mode controller evaluates the magnetic bearing control currents which bring the rotor response to the sliding mode surface and cause it to remain within the boundary layer. A treatment of uncertainty limits is developed for unknown bearing open loop stiffness, actuator gain, and mass unbalance. A numerical simulation showed the desired system response when the rotor was subjected to large initial transient conditions.