A Planar Actuator with a Small Mover Traveling Over Large Yaw and Translational Displacements

We report a three-degree-of-freedom actuator with a small mover that can travel over large displacements on a plane. Such direct drives with multiple degrees of freedom are an emerging technology because of their high performance. Previously, we designed planar actuators capable of generating thrusts anywhere in the movement area and successfully demonstrated the two-dimensional drive of the actuator in the translational direction. However, during translational motion control on the plane, a slight oscillatory yaw motion occurred. Thrusts and torques of the actuator are proportional to the - and -axis currents, which generate flux densities with 90 and 0 phase-leads, respectively, from the flux density generated by the permanent magnets of the mover. Therefore, the thrusts and torques can be generated independently by the - and -axis current control. In our new design, we use a decoupling control on the planar actuator to control both yaw and translational motions on the plane. We describe the experimentally obtained drive characteristics of this actuator. The experimental results indicate that the mover can travel over large yaw and translational displacements independently and simultaneously with relatively precise positioning and response. Thus, we have demonstrated satisfactory performance of a planar actuator with three degrees of freedom.