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Simulation of MEMS Vibratory Gyroscope through Simulink 
 
Chandradip Patel1 
Patrick McCluskey2 
1,2CALCE Electronics Products and Systems Consortium 
Department of Mechanical Engineering, A. James Clark School of Engineering 
University of Maryland, College Park, MD USA, 20742, Phone: (301)-405-0279. 
1E-mail: cpatel@umd.edu , 2E-mail: mcclupa@umd.edu 
 
ABSTRACT 
Microelectromechanical systems (MEMS) vibratory gyroscopes are increasingly used in applications 
ranging from consumer electronics to aerospace and are now one of the most common MEMS products 
after accelerometers. With advances in fabrication technologies, the low-cost MEMS gyroscope has 
opened up a wide variety of applications with environmental conditions ranging from mild to harsh. 
Specific applications in harsh environments have demanded robust MEMS gyroscopes that require 
extensive lab testing to assess performance. The objective of this paper is to develop an efficient and faster 
approach to simulate the behavior of the MEMS vibratory gyroscope. Simulink is a toolbox in MATLAB 
for modeling, simulating and analyzing multi-domain dynamic systems. The MEMS vibratory gyroscope is 
a two degree-of-freedom spring-mass-damper system. With known values of mass, spring stiffness and 
damping coefficient in the drive and sense direction, the characteristic equations of motion of the MEMS 
vibratory gyroscope can be easily solved by the Simulink model developed in this paper. This Simulink 
model can also be used to simulate the temperature dependent characteristics of a MEMS vibratory 
gyroscope. 
 
INTRODUCTION 
MEMS inertial sensors, including the accelerometer and the gyroscope, have gained much attention in the 
past few years. Their unique features compared to macro-scale devices have made them popular in many 
applications. Nowadays, MEMS gyroscopes are lighter, smaller and consume less power and therefore, are 
considered to be the best low-cost solution compared to spinning disk or wheel type mechanical 
gyroscopes. MEMS vibratory gyroscopes are increasingly used in applications ranging from consumer 
electronics to aerospace and are now one of the most common MEMS products. Typical applications of 
MEMS gyroscopes in the consumer market include image stabilization in digital cameras and camcorders, 
remote controllers in virtual gaming devices and motion sensing in next-generation mobile phones and 
tablets. Other market applications of the MEMS gyroscope include automotive, medical, aerospace, 
defense and robotics. 
 
In such applications, consumers demand MEMS gyroscopes that are not only intelligent and efficient but 
also reliable even in harsh environments. It is therefore important to characterize the MEMS gyroscope’s 
performance reliability in such environments. Device characterization is also an essential part of the 
product development phase. In many cases, device characterization is a very expensive and time 
consuming process. Thus, there is a significant need for developing an efficient and faster approach that 
simulates the behavior of MEMS vibratory gyroscopes. Due to the high demand of the MEMS gyroscopes 
in consumer electronics, most of the commercial-off-the-shelf (COTS) MEMS gyroscopes have the limited 
operating temperature range of -40˚C to +85˚C. In many applications like navigation and tracking, deep 
energy exploration, down hole drilling and high temperature industrial applications, the MEMS gyroscope 
sensor experiences temperatures that are beyond a manufacturer’s recommended temperature range. In 
those cases, it is important to quantify gyroscope behavior at those temperature conditions. However, 
laboratory experiments at each temperature condition are usually expensive, time consuming and tedious. 
Thus, a simulation approach is preferred. 
 
WORKING PRINCIPLE 
The MEMS gyroscope is a sensor that measures the 
rate of change in the angular position of an object. A 
majority of the reported MEMS gyroscopes use 
vibrating mechanical elements to sense angular 
velocity [1]. A MEMS vibratory gyroscope can be 
simply visualized as a two degree-of-freedom spring-
mass-damper system as shown in Figure 1. At the 
core, it has a vibrating mass (proof mass). The proof 
mass is suspended above the substrate by use of 
flexible beams, which also work as mechanical 
springs. In most of the work on reported MEMS 
vibratory gyroscopes, the proof mass is subjected to 
vibration at resonance frequency by use of an 
electrostatic force causing movement in the drive 
direction. When the gyroscope sensor experiences an 
angular rotation, a Coriolis force is induced in the 
direction orthogonal to both the drive direction (x) and angular rotation axis (z). This rotation induced 
Coriolis force causes an energy transfer between the drive mode and the sense mode. The proof mass 
movement caused by the Coriolis force in the sense direction (y) is proportional to the angular rotation 
applied and can be measured with differential capacitance techniques by use of interdigitated comb 
electrodes. One example of such construction of a MEMS vibratory gyroscope is shown schematically in 
Figure 2. 
 
In some cases, a MEMS gyroscope has two proof masses 
placed on either side that are driven in opposite directions 
causing the Coriolis force induced on the two masses to be 
in opposite directions as shown in Figure 3. This special 
arrangement helps to nullify the external inertial inputs 
caused by undesirable ambient vibration and shock. 
 
One of the specific applications of these gyroscopes is 
inertial navigation where single axis MEMS vibratory 
gyroscopes are combined and mounted on three Cartesian 
directions (i.e., X, Y and Z) with other electronics. This 
tracking system requires robust and accurate gyroscopes, 
the performance of which should be maintained within a 
desired specific range over a specified time period. 
 
Figure 3: Two Proof Mass-Spring-Damper System 
Figure 1: Schematic Illustration of MEMS 
Vibratory Gyroscope 
Figure 2: MEMS Gyroscope Construction 
 
In order to derive the equation of motion for the MEMS 
vibratory gyroscope, the system is represented by a two 
degree-of-freedom, spring-mass-damper system. Since the 
gyroscope structure movement is modeled while it rotates, 
motion equations can be represented based on a stationary 
frame (gyroscope frame) and non-stationary frame (inertial 
frame) which is shown in Figure 4. 
 
The spring-mass-damper system is initially observed with 
respect to the gyroscope frame. Once the motion equations 
have been established, these equations are derived with 
respect to the inertial frame. The equations of motion for 
the spring-mass-damper system with respect to the 
gyroscope frame can be represented as 
 ��������� + ���� + ��	 = �� A 
 ��
 + �
�
 + �
� = 0 B 
Where m is the mass of the vibrating structure, cx and cy 
are the damping coefficient in drive and sense direction, kx 
and ky are the beam stiffness in drive and sense direction, ax and ay are the acceleration components and vx 
and vy are the velocity components in the drive and sense direction respectively and Fd is an electrostatic 
force applied by drive combs. If these equations are viewed from an inertial frame, they can be represented 
as, 
 �	� + ��	� + ��	 = ��+2��� C 
 ��� + �
�� + �
� = −2�Ω	� D 
The 2m�� and 2m�� are the rotation-induced Coriolis terms. When the gyroscope starts vibrating in the 
drive direction and experiences external angular rotation, these Coriolis terms cause dynamic coupling 
between the drive and sense modes of vibration and because of this coupling, the suspended proof mass 
starts to vibrate in the sense direction. 
 
SIMULINK MODEL 
In order to calculate the drive and sense comb displacement from the characteristic equation of motion, it is 
necessary to solve equations C and D. There are various methods to solve these coupled differential 
equations. The one used in this paper is through Simulink. Simulink is atoolbox in MATLAB for 
modeling, simulating and analyzing multi-domain dynamic system. A Simulink model is developed by 
rearranging equations C and D as shown below. 
 	� = � 1� (�� + 2�Ω�� − ��	� − ��	) E 
 �� = � 1� (−2�Ω	� − ���� − ���) F 
From equations E and F, a Simulink model is developed that is shown in Figure 5. To calculate drive and 
sense displacement for a specific angular rotation through the Simulink model, the values of mass of 
suspended structure, stiffness in drive and sense directions, the damping coefficient in drive and sense 
Figure 4: Two Degree of Freedom System 
Model 
 
directions and electrostatic force are required. In such a case, the following equations can be used to 
calculate these parameters. 
 
Figure 5: Simulink Model 
 
The mass of suspended structure (M) can be calculated as [2]: 
 � = �� +��� + �� − �� G 
Where Mm is mass of inner and outer frames, Mb is suspension beam mass, Mc is drive and sense combs 
mass and Me is etch holes mass respectively. 
 
The drive beam stiffness (Kx) and sense beam stiffness (Ky) depend on the gyroscope design. Based on the 
configuration of the MEMS gyroscope considered in this study, which is similar to construction shown in 
Figure 2, the following equation can be used [1]: 
 �� = �
 = 4��� �!"�!#$�!# +
4��� �%"�%#$�%# H 
Where E is Young’s modulus of poly-silicon, tb1 and tb2, wb1 and wb2, lb1 and lb2 are thickness, width and 
length of beam 1 and beam 2, respectively. 
 
From the mass of suspended structure (M), drive beam stiffness (Kx) and sense beam stiffness (Ky) 
calculated previously, drive mode frequency (fx) and sense mode frequency (fy) can be calculated as [3]: 
 &� = 12Π(��� , &
 = 12Π(�
� I 
 
In order to determine the flow regime to calculate the damping coefficient, the Kundsen number (Kn) can 
be calculated as [1]-[2]: 
 �* =� +,� � = � -�./2�0�1%�234�,� J 
Where � is mean free path of the gas molecule, Lc is a characteristic length of flow, R is a gas constant, T is 
ambient pressure, D is the diameter of the gas molecule, Na is Avogadro number, and P is ambient 
pressure. 
 
Based on the values of Knudsen number (Kn), the flow regime is determined, and based on that the proof 
mass damping coefficient (Cproof mass) and comb structure damping coefficient (Ccomb structure) can be 
calculated as [2][3][4]: 
 567889��3:: =�;�<=7889��3::(1 + 2��*)ℎ K 
Where µ is air viscosity, Aproof mass is proof mass area, Kn the is Knudsen number and h is the gap between 
proof mass and substrate. 
 5?8���:@7A�@A7�� =�;��2�<�8��:B� + �+ L 
Where µ is air viscosity, N is the number of combs, Acombs is the comb area, gc is the gap between comb 
finger and � is the mean free path of the gas molecule (Kn* Lc). 
 
The net damping is the summation of damping of the proof mass and comb structure. Thus, drive damping 
coefficient (Cdrive) and sense damping coefficient (Csense) can be calculated as [2][3][4]: 
 5�7CD�� =�5:�*:� �= ��567889��3:: +�5?8���:@7A�@A7�� M 
The selected device is actuated by electrostatic combs. Thus, net electrostatic force (Fd) can be calculated 
as [1], [3]: 
 �� =�2.28�2� ∈ � � �H��H3��B� N 
Where N is number of the capacitor formed by the comb finger, � is permittivity of air, Vdc is DC voltage, 
Vac is AC voltage and gc is the gap between the comb fingers. 
 
RESULTS 
Based on the above parameter values, a Simulink model, shown in Figure 5, can be used to calculate drive 
and sense comb displacement. In many cases, sense combs use interdigitated comb electrodes to measure a 
differential capacitance that is directly proportional to sense comb displacement. This differential 
capacitance can eventually be converted with the help of an ASIC to a voltage that is measured from the 
gyroscope output terminal. The differential capacitance or capacitance change (�Cb) can be calculated 
from sense displacement as [2] [4]: 
 ∆5� =�J�$6_� � � �L:�*:�(B�)% O 
 
Where � is the permittivity of air, lp_c is a comb finger overlap, tc is comb finger thickness, Ysense is a sense 
displacement, gc is the gap between comb fingers. The above parameters are calculated with the help of 
equations G through O, and drive and sense displacement are calculated from Simulink model at 60˚/s 
angular rotation. These values are summarized in Table 1. The time dependent response of the drive and 
sense combs at 60˚/s angular rotation are shown in Figure 6 and Figure 7. 
 
Figure 6: Drive Comb Displacement (m) vs. 
Time (sec) at 60˚/s Angular Rotation. 
 
 Figure 7: Sense Comb Displacement (m) vs. 
 Time (sec) at 60˚/s Angular Rotation. 
 
From the Simulink model, output of the MEMS vibratory gyroscope at different angular velocities can be 
calculated to determine the scale factor. One example is shown with angular velocity ranges from -50 RPM 
to 50 RPM in Figure 8. 
 
The Simulink model discussed earlier can also be used to simulate the temperature dependent characteristic 
of the MEMS vibratory gyroscope. Literature suggests that a prime source of temperature dependent bias 
in the MEMS gyroscope is a change in resonance frequency and Q-factor. Resonance frequency is a 
function of stiffness which depends on Young’s modulus. A material property, Young’s modulus (E) is a 
0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 10
-3
-6
-4
-2
0
2
4
6
x 10
-6
Time (Sec)
D
ri
v
e 
D
is
p
la
ce
m
en
t 
(m
)
1 2 3 4 5 6
x 10
-3
-6
-4
-2
0
2
4
6
x 10
-9
Time (Sec)
S
en
se
 D
is
p
la
ce
m
en
t 
(m
)
Parameters Calculated values 
Mass of suspended structure (�) 4 (;B) 
Drive beam Stiffness (��) and 
Sense beam Stiffness (�
) 30.95 (2/�) 
Drive mode frequency (&�) and 
Sense mode frequency (&
) 14,000 (NO) 
Kundsen number (�*) 0.0334 
Proof mass damping coefficient 
(567889��3::) 7.61e-6 (2P/�) 
Comb structure damping 
coefficient (5?8���:@7A�@A7��) 1.37e-7�(2P/�) 
Drive damping coefficient 
(5�7CD��) 7.75e-6 (2P/�) 
Sense damping coefficient 
(5:�*:�) 7.94e-6 (2P/�) 
Electrostatic force (��) 4.36e-6 (2) 
Angular velocity (�) 60 (ᵒ/P) 
Drive displacement (R�7CD�) 6.39 (;�) 
Sense displacement (L:�*:�) 6.75 (S�) 
Capacitance change (∆5�) 7.45e-18 (&) 
Table 1: Simulation Results 
 
function of temperature and thus different values of Young’s modulus at different temperatures change the 
resonance frequency of the vibrating mass. The Q-factor is the ratio of loss of energy to the stored energy 
in one cycle. A high Q value of an oscillator indicates a lower rate of energy loss relative to the stored 
energy. Thus, different values of damping coefficients at different temperatures change the Q factor of the 
vibrating mass. When the value of Young’s modulus and the damping coefficient are known at different 
temperatures, the Simulink model developed in this paper is used to simulate the temperature dependent 
characteristic of the MEMS vibratory gyroscope. In this way, expensive, time consuming and tedious 
laboratory experiments can be easily avoided. 
 
Figure 8: Capacitance Change (f) vs. Angular Velocity (RPM) 
 
CONCLUSION 
In this study, a Simulink model is developed that can be used to simulate the behavior of the MEMS 
vibratory gyroscope. With the known values of mass, spring stiffness and damping coefficient in drive and 
sense direction, the characteristic equations of motion of the MEMS vibratory gyroscope can be easily 
solved by developed Simulink model that replaces expensive, time consuming and tedious laboratory 
experiments. It is also shown that the developed Simulink model can also be used to simulate the 
temperature dependent characteristic of the MEMS vibratory gyroscope. 
 
ACKNOWLEDGEMENT 
The authors would like to acknowledge the financial and technical support of the Maryland Industrial 
Partnership Program and TRX Systems, Inc. The authors would also like to thank the CALCE Electronic 
Products and Systems Center for the use of their laboratories in the conduct in this work. 
 
REFERENCES 
[1] C. Acar and A. Shkel,"MEMS Vibratory Gyroscopes-Structural Approaches to Improve Robustness," 
in MEMS Reference Shelf Series, New York: Springer, 2009. 
[2] N. Patil, "Design and Analysis of MEMS Angular Rate Sensors," Master’s Thesis, Indian Institute of 
Science, Bangalore, India, 2006. 
[3] V. Kaajakari, "Practical MEMS: Design of Microsystems, Accelerometers, Gyroscopes, RF MEMS, 
Optical MEMS, and Microfluidic Systems. Small Gear Publishing, 2009. 
[4] S. Mohite, N. Patil, and R. Pratap, "Design, Modeling and Simulation of Vibratory Micromachined 
Gyroscopes," Journal of Physics: Conference Series, vol. 34, pp. 757-763, Apr. 2006. 
 
 
-50 -40 -30 -20 -10 0 10 20 30 40 50
-4
-3
-2
-1
0
1
2
3
4
x 10
-17
Angular Velocity (RPM)
C
ap
ac
it
an
ce
 C
h
an
g
e 
(f
)