Virtual Rate-Table Method for Characterization of Microgyroscopes

In this paper, we demonstrate a testing method for characterization of microgyroscopes using a virtual rate-table, which uses a series of voltage signals to emulate the Coriolis force induced by the angular rate inputs to obtain the frequency response of the gyroscope. The proposed approach holds the following advantages: 1) it provides a convenient and efficient way to evaluate the scale factor and bandwidth of the gyroscope operating in either open-loop mode or closed-loop mode, the laborious debugging by frequently utilizing the real rate-table can be avoided; 2) it can easily identify the dynamic response to external angular rate, which is the control plant during the rebalance control design for the sense mode in a large frequency range, avoiding the performance limit of the ordinary rate-table; and 3) it can be used in a self-test for the microgyroscope system for the error calibration and malfunction checking. The method was applied to a decoupled
z
-axis gyroscope. The test results show that the measured scale factor and bandwidth are 30.2 mV/(deg/s) and 8.0 Hz by the virtual rate-table method, which are in close agreement with the conventional rate-table method, i.e., 31.0 mV/(deg/s) and 7.4 Hz. The static calibration with the virtual rate-table was also evaluated. The scale factors measured with the conventional rate-table method and the virtual rate-table method are 31.0 mV/(deg/s) and 30.1 mV/(deg/s) with R
²
nonlinearity of 0.03% and 0.02%, respectively.