Positioning performance of L-shaped seal mechanism with 3-degree 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 x- and y-directions and rotates up to submilliradian steps in the /spl theta/-direction. The seal mechanism performs as well as the inchworm mechanism. Positioning accuracy in each direction is twice as small as the moving step. The seal mechanism has a smaller number of controlled actuators and is driven by a smaller number of steps than the multiple-DOF positioning stages employing the inchworm mechanism.