Positioning Performance of L-Shaped Seal Mechanism with 3 Degrees of Freedom

–This paper deals with a small mobile device, "Seal Mechanism," with three degrees of freedom (DOFs). An L-shaped structure of Seal Mechanism is proposed. This device consists of two controlled Electromagnets FA and FB connected by two Piezoelectric actuators EA and EB with Electromagnet FC that generates a constant friction. The friction at FA and FB are alternated by an on-off control. The whole device wriggles with Electromagnets FC by deforming Piezoelectric actuators. The 3-DOF device can move up to micrometer steps in the xand y-directions and rotates up to submilliradian steps in the θ-direction. Seal Mechanism performs as well as the inchworm mechanism. Positioning accuracy in each direction is twice as small as the moving step. Seal Mechanism has smaller number of controlled actuator and is driven by smaller number of steps than the multiple-DOF positioning stages employing the inchworm mechanism. Keywords––Piezoelectric element, Positioning, Linear drive, Mobile device, Friction, Scanning probe microscope.