High-Speed and High-Resolution Linear Microstepper Based on Toggle Mechanism Actuated by Electromagnet

Novel linear microsteppers are designed for high-speed and high-resolution positioning actuators. In general, most microsteppers equipped with a multi-layered piezoelectric actuator for positioning have difficulty to improve their feed rate because of the small stroke of the actuator, despite their excellent positioning resolution. The microstepper in this study employs two electromagnets for clamping the rail, and one electromagnet for longitudinal actuation of the mechanism. Use of electromagnets with a larger stroke enables a high-speed feed rate and allows for the use of inexpensive low-voltage amplifiers. Moreover, the toggle mechanisms reduce the actuator’s displacement and enlarge the actuator’s force. Because the relation between the input and output displacements of the toggle mechanism is non-linear, the microstepper achieves both high-speed and high-resolution positioning as necessary. This paper deals with experimental mechanisms equipped with two types of actuators based on one or two gaps between the armature and the iron core of the electromagnet. First, the fundamental design of the microstepper with two toggle mechanisms actuated by an electromagnet is introduced. Next, an experiment using each of the two sets of microsteppers we manufactured is described. As a result, the microsteppers are capable of of 1 mm/s maximum speed and a positioning resolution better than 0.1 µm.