A Novel Scale Factor Calibration Method for a
MEMS Gyroscope Based on Virtual Coriolis Force
Jimeng Zhang
1,2
, Chunhua He
2
, Yuxian Liu
2
, Dachuan Liu
2
, Qiancheng Zhao
2
, Zhenchuan Yang
*2
and Guizhen Yan
2
1
Shenzhen Graduate School, Peking University
2
National Key Laboratory of Science and Technology on Micro/Nano Fabrication,
Institute of Microelectronics, Peking University,
Beijing, 100871 China
*Email: z.yang@pku.edu.cn
Abstract—This paper presents a novel scale factor
calibration method for a MEMS vibratory gyroscope based on
virtual Coriolis force. Frequency and amplitude
programmable voltage signals generated by the system can be
used to emulate the Coriolis force induced by external angular
rate signals. The system contributes to the development
procedure of control system for gyroscope and provides a scale
factor calibration method for the digital control system of a
gyroscope. The experiment results show the digital system can
acquire the frequency response of gyroscope and detect the
frequency response of reference virtual rate signal effectively.
Keywords—MEMS gyroscope; virtual Coriolis; scale factor
calibration; self-test
I. INTRODUCT ION
MEMS v ibratory gyroscopes have wide range
applications in various fields for their outstanding features
such as small size, low cost as well as good integration
capability. The optimu m perfo rmance of the sensor not only
depends on the mechanical structure design, but also the
signal conditioning circuit. In recent years, the digital
control system is popularly used for MEMS gyroscopes,
because it’s precise, robust against environment variations,
and flexible to design.
Scale factor is the relation of the measured voltage and
the input angular rate. A tradit ional method to evaluate scale
factor is based on the real rate-table, which may be difficult
when the frequency response testing needs the angular rate
with several hundred hertz frequency. Besides, self-test and
real time calibration of the scale factor after being installed
is necessary when it operates in extreme environ ments. In
such case, the working environment may change
significantly and it may be unfeasible to test the gyroscope
using the real rate-table.
Some scale factor self-calibration techniques are
reported in the literature. In [1], a modulated square-wave
dither signal works as the virtual rate signal of a closed-loop
operated vibratory gyroscope to continuously detect and
calibrate the scale factor drift. However, the calibration can
be only achieved by using the whole-angle mode of the
MEMS Quad Mass Gyroscope, it can’t be used in traditional
vibration gyroscopes . Another scale factor self-calibration
method [2] generates a reference to Coriolis force by using
the gravitational force on the gyroscope proof mass to
obtain the scale factor of the gyroscope. However, this
method is static calibration, which can’t be used when the
gyroscope is mounted on the object. Another scale factor
calibrat ion method is using an additional oscillator to
superimpose another vibration with a certain signal to the
normal vibration for angular measurement [3]. Then the
response of the certain signal shows the operation status of
the sensor and can be used as a reference for scale factor
calibrat ion. Obviously, the disadvantage is that there must
have the additional oscillator added in the mechanical
structure.
This paper presents a novel scale factor calibration
method for a M EMS v ibratory gyroscope based on virtual
Coriolis force [4]. The v irtual Corio lis force is feasible to
emu late the high frequency external angular rate and can be
easily achieved by exciting a part of force feedback
electrodes by the modulated signal constructed from v irtual
vibration velocity and virtual angular rate signals. The
designed digital system in this paper can detect the
frequency response of the reference v irtual rate signal
effectively. As the frequency response of virtual Coriolis
force can reflect the working environment changes of the
gyroscope, it provides a self-test method and makes it
possible for the real time calibrat ion of scale factor for a
gyroscope.
II. PRINCIPLE OF OPERAT ION
A. Vrtual Coriolis force analysis
Real Coriolis force
Real Coriolis force
Virtual Coriolis force
Virtual Coriolis force
Fig. 1. Virtual Coriolis force and real Coriolis force signal flow for a
gyroscope.
Proceedings of the 10th IEEE International Conference on
Nano/Micro Engineered and Molecular Systems (IEEE-NEMS 2015)
Xi’an, China, April 7-11, 2015
978-1-4673-6695-3/15/$31.00 ©2015 IEEE
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