L-shaped seal mechanism with 3 degrees of freedom

This paper deals with a small mobile device, seal mechanism, with three degrees of freedom (DOF) for a scanning probe microscope. An L-shaped structure of seal mechanism is proposed to reduce the interference among the axes. This device consists of two controlled electromagnets CA and CB connected by two piezoelectric actuators PA and PB with electromagnet CC that generates a constant friction. The friction at electromagnets CA and CB are changed by on-off control. The whole device wriggles (like a seal) with electromagnets CC when the piezoelectric actuators extend and contract. The 3-DOF device can move up to micrometer steps in the x- and y-directions and rotates up to submilliradian steps in the θ-direction. The movable range is infinite in principle. Performance of coarse mode is investigated in detail. Seal mechanism performs as well as the inchworm mechanism. Seal mechanism has smaller number of controlled actuator and is driven by smaller number of steps than the multiple-DOF positioning stages by using the inchworm mechanism