Look-Up Table Based Real-Time Commutation of 6-DOF Planar Actuators

Synchronous planar actuators with moving magnets, stationary coils and a 6-DOF magnetic suspension are complicated to control. It is not possible to decouple forces and torques by applying a sinusoidal commutation scheme as is common in regular synchronous AC motors. Several commutation methods are developed based on the coupling matrix, that links the current in each coil to the force and torque vector on the actuator. Accurately calculating this position varying coupling matrix in real-time while the actuator is moving, is critical in controlling the planar actuator. In this paper, a look-up table based method is proposed that uses several small look-up tables and symmetries in the design that allows accurate real-time calculation of the coupling matrix.