Displacement amplification enhances rapid actuation of electromagnetic actuators: Drive with load of spring–mass–damper system

Abstract

Displacement amplification affects the response time of actuators using electromagnetic attractive force. Although this force is widely used for actuation, it exhibits a tradeoff between thrust and stroke, because thrust depends on the gap between the electromagnet and armature, and increasing the gap (stroke) drastically degrades thrust. Displacement amplification has been proposed for actuators to mitigate this tradeoff by magnifying the gap motion to efficiently use large forces in small gaps. Although such an actuator is applicable to submillimeter stroke and fast motions, dynamic characteristics have not been studied enough for designing in practical usages. This paper reveals the effect of displacement amplification on the actuation time through both a simple dynamic model for basic theoretical discussion and a simulation including damping factor to gain a more practical perspective. We also propose a test bench to verify the analyses and compare experimental and simulation results. The experiments confirm shorter actuation time and thus improved performance by combining electromagnetic attractive force and displacement amplification with spring–mass–damper as load. In addition, the experimental and simulation results show that only characteristics of the magnetic circuit should be considered for deciding the amplification ratio in designing DAEAs.