Fabrication and Control of an Electrostatically Levitated Rotating Gyro

There are significant efforts to develop gyroscopes using MEMS technology; accuracies of gyroscopes varying from rate-grade, through tactical-grade, to inertial grade. The random walk varies from 0.5 o /√h through 0.05 o /√h to 0.001 o /√h. The most common approach is to use vibratory gyros, which use mechanical elements (proof-mass) to sense the rotation. There are several types of vibratory gyroscopes now commercially available from Robert Bosch, BEI Syrtron Donner, Silicon Sensing Systems, MEMSens, and Analog Devices. Any higher accuracy gyroscopes require a rotating disk which is electrostatic levitated and spun. This device also does not have bearings and with large spinning velocity very high accuracy can be obtained. There are two publicly known attempts to develop MEMS rotating gyroscopes, one in Japan by the group associated with Tokimec and a similar concept is being developed in Europe led by M. Kraft. The European approach has more theoretical character. At AMNSTC we developed and fabricated another rotating gyroscope, which differs from the Tokimec design in several ways: three instead of four levitation electrodes are used, new 6 phase or 4 phase spinning concepts are implemented, better layout of vertical electrodes was used, new concept of vias were developed, and new fabrication method was developed, which used standard MEMS processing with as few as 5 masking steps, allowing the realization of low cost inertial measurement systems. Several batches of gyroscopes were fabricated and measured.