Nonlinear Regulator Design for Grinding AMB Spindle Based on Optimal Control

For AMB system with high stiffiiess, such as applied in grinding, the system can be treated as linearity, only if the rotor operates among a small range of linearity. At this condition, linear control system designing is satisfaction. However, once the rotor operates out of the linear range, its real performance will gradually become worse. To be aimed at this question, this paper put forward a linear optimal control at first, and then, a nonlinear variable gain control for high stiffiiess and good stabilization, by using 3-D frequency domain analyzing method. The method especially suits for such a system whose regulator is made of analogue circuit.