Lookup NU author(s): Dr Zhongxu Hu,
Dr Barry Gallacher
This is the authors' accepted manuscript of an article that has been published in its final definitive form by IEEE, 2019.
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Electrostatic MEMS Coriolis vibratory gyroscopes (CVG) are essentially nonlinear because of the capacitive transducers employed for the excitation and detection of resonance vibration. This paper investigates the influence of nonlinearity on the precession angle dependent bias error of a MEMS rate integrating gyroscope (RIG) and proposes a novel correction to minimize this effect. A linear model of CVGs is commonly used in the dynamic analysis and control of MEMS RIGs. The linear model predicts a 2nd harmonic angular drift error  due mainly to non-proportional damping. However, experimental results from previous work  demonstrate the existence of an additional 4th harmonic component in the precession rate, as well as in the resonant frequency and quadrature control. Analysis and removal of this high order error term will further improve the accuracy of RIG. Here, it is shown that high order angularly modulated drift error is the result of nonlinear damping, and that the stiffness nonlinearity is responsible for the 4th harmonics present in the fluctuation of the operating frequency and in the control for quadrature nulling. It is understood that nonlinear damping may be introduced electrically by the energy sustain state feedback control that uses nonlinear capacitive measurements. Nonlinearity correction is proposed to the capacitive displacement detection which significantly reduces the high order drift error. Simulation and experimental results are provided to validate the analysis. A DSP controlled MEMS RIG with nonlinearity correction exhibits an angular drift error of less than 0.2 deg/s.
Author(s): Hu Z, Gallacher B
Publication type: Article
Publication status: Published
Journal: IEEE Sensors
Print publication date: 15/11/2019
Online publication date: 16/07/2019
Acceptance date: 15/07/2019
Date deposited: 16/07/2019
ISSN (print): 1424-8220
ISSN (electronic): 1424-8220
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