Analysis and fabrication of reciprocal motors applied for microgyroscopes

Abstract

For microgyroscopes, the angular rate detection components have to oscillate forward and backward, alternatively. An innovative design of a microelectromagnetic drive module is proposed to make a -type thin disk reciprocally and efficiently rotate within a certain of angular interval. Twelve electromagnetic (EM) poles, with iron cores at the center and wound by electroplated copper wires, enclosing the thin disk are designed to provide the magnetic drive power. An isotropic etching technique is employed to fabricate the high-aspect-ratio trench, housing of the follow-up electroplated copper, so that the contact angle of wire against the trench can be increased and the potential defect of cavities and pores within the wire can be prevented. On the other hand, a -type thin disk, with a central bearing and a set of auxiliary bushings, is designed to conduct the pitch motion as an angular excitation, in addition to spinning, is exerted on the gyroscope. That is, the angular motion of the disk is two-dimensional: spinning, driven by the EM poles, and tilting, to respond to the exerted angular rate due to Coriolis effect. The efficacy of the micromagnetic drive module is verified by theoretical analysis and computer simulations by the commercial software, Ansoft Maxewll. In comparison to the conventional planar windings in microscale systems, the magnetic drive force is increased by 150%.