An XYΘ actuator with a closed-loop magnetic field

Precise positioning with multi degrees of freedom is needed in precision engineering. We formerly proposed two actuators that could move in X, Y and Θ directions by expansion of piezoelectric actuators and by adhesion of electromagnetic actuators. One was a Y-type actuator, and the other was a Δ-type actuator. These actuators were used on a magnetic floor. The 100 nm resolution of the linear displacement and the 500 nrad resolution of the angular displacement were obtained by these actuators. However, we could not obtain the same result on a slope. The magnetic force generated by the electromagnetic actuator was so small that the electromagnetic force could not hold the actuator on the slope. This was why a small gap between the yoke of the electromagnetic actuator and the magnetic floor reduced the electromagnetic force. In this paper we will revise configurations of the proposed actuators. A closed-loop magnetic field, which passes through the actuator and the magnetic floor, makes the electromagnetic force larger and the actuators can be driven on a slope and a wall. A sequence of the revised actuator is more complicated than that of the previous one, because two electromagnetic actuators must adhere to the floor. Since the electromagnetic force generated by the revised actuator is larger than that of the previous one, the revised actuators will be able to move on a wall