Precise motion control of a hybrid magnetic suspension actuator with large travel

A novel hybrid magnetic suspension actuator (HMSA) that can be used for positioning applications with sub-micron resolution and millimeter range has been developed. The proposed actuator can generate levitation with reduced power consumption by using permanent magnets to provide repulsive force and a coaxial coil for the attractive force. It will enable modular implementation of millimeter-range multi-DOF magnetically suspended platforms with large load capacity and fast response by controlling independent axis of motion with low power consumption and resolution only limited by the accuracy of the sensing system. To achieve precise positioning over a long range of travel while keeping fast response, an enhanced digital quasi-sliding mode controller with reaching law has been implemented and its performance compared to that of standard feedback linearization. The controller has been implemented in a DSP platform and its performance evaluated and compared through stabilization and tracking experiments. A fast reaching rate with low chattering has been demonstrated, showing the advantages of the proposed actuator and controller in magnetic suspension applications requiring both long range of travel and fast response.