A characterization of the performance of MEMS vibratory gyroscope in different fields

Abstract

Compared with traditional spinning disk or wheel mechanical gyroscopes, MEMS gyroscopes are lighter in weight, smaller in dimension, lower in cost and energy saving. MEMS gyroscopes have been important components in consumer electronics, automotive electronics, etc. MEMS gyroscope is a rotation sensing component, and that means working in dynamic environment where acceleration, temperature and electromagnetic field may vary by time. It's necessary for us to know how much influence the environmental conditions have on the performance of MEMS gyroscopes. Knowing that characterization helps engineers to calibrate MEMS gyroscopes and get better outputs. The environmental conditions in this paper are magnetostatic field, electrostatic field and alternating magnetic field. The MEMS gyroscope's output noise is highly dependent on the number of sampling data as well as the duration of the measurement. To reduce random error, the angular rate to be analyzed is an average of 60 to 90 seconds of the initial output. By long term static test in field-free environment and comparison with external field applied test, it is possible to characterize the noise feature of MEMS gyroscopes' output. Comb structures in the MEMS gyroscope are driven by electrostatic force. The electromagnetic field will distract the motion parts from the ideal direction of motion, which leads to output deviation [1]. Three types of electromagnetic field are concerned in this article, which are electrostatic field, magnetostatic field and alternating magnetic field. The electric field is generated by a parallel plate capacitor with its zero potential reference connected to the GND pin of the MEMS gyroscope. The magnetostatic field is generated by magnets. The alternating magnetic field is generated by a coil. The output deviation under magnetostatic filed is within 0.6 degree/s, and there's obvious linear relationship between magnetic induction intensity. The output deviation under electrostatic filed is within 0.13 degree/s, which is smaller than that of under magnetostatic filed, and is irregular. An output deviation peak appears nearby the resonance frequency of the gyroscope. Characterization of the behavior of the MEMS gyroscope in such filed environments is an essential process for ensuring their reliable use and is helpful for acquiring more accurate results.