Design and Simulation of a MEMS
High G Inertial Impact Sensor
Y.P. Wang1, R.Q. Hsu1, C.W. Wu2
1Department of Mechanical Engineering, National Chiao Tung University,
1001 Ta-Hsueh Road, 300 Hsinchu, Taiwan
Phone: +886-3-5712121 Ext.31934, Email: anitawu.wlh@msa.hinet.net
2Department of Mechanical and Mechatronic Engineering, National Taiwan
Ocean University
2, Pei-Ning Road, Keelung, Taiwan.
Speaker: Jing-Wen Shih
Outline






Introduction
The major goal of Inertial impact sensor
The micro impact sensor proposed in this
study
Simulation
Conclusion
Reference
Introduction


Inertial sensors have been extensively
utilized in science like inertial navigation
systems and airbag triggers .
For high G(>300G) applications. Reaction
times for conventional mechanical type
impact sensors are not fast enough.
The major goal of inertial impact
sensor

Designing an impact sensor that has a faster
reaction time than conventional sensors and
a mechanism that is sufficiently robust to
survive the impact when a vehicle collides
with a hard target is the major goal of this
study.
Conventional inertial impact
sensor

(a)cantilever beam type

(b)axial spring type
MDS System trigger

MDS: Mass- Damper- Spring Dynamic

Proof mass expressed by dynamic equation
lamped system:

Use Laplace transformation to the second –
order function for acceleration mass:
The micro impact sensor proposed
in this study
To evaluate system reaction time, 4 different
arrangements of spring and proof mass were
tested.
The proof mass scale and coil
number of the sensor
Simulation

Displacement versus applied forces for
each sensor
The response time of the microsensor
Proof mass increases from 0.62 to 1.0, and the
spring constant remains unchanged, the
reaction time is decreased.
Minimum G values for the sensors
to be triggered
Reducing the spring constant, and retaining the proof
mass, the reaction time decreased and the trigger G
value decreased for sensors
Minimum G values for the sensors
to be triggered
The plastic strain of the type 1
sensor in 21000G

With no significant interference in the x and z
axis; consequently,sensor stability is very
good.
Conclusion


This proposed impact sensor is intended for
use at 8,000–21,000G. Four different designs
were analyzed.
The impact sensors were sufficiently robust
to survive the impact of at least 21,000G, four
times higher than that of conventional inertial
impact sensors.
References







F. Goodeough, Airbag boom when IC accelerometer sees 50
G,Electronics Design, pp.45-56, August. 8, 1991.
Tadao Matsunaga, Masayoshi Esashi, Acceleration switch with
extended holding time using squeeze film effect for side airbag
systems, Sensors and Actuators A：physical, vol. 100, Issue 1, pp.1017 , August. 2002.
Military Standard, Mechanical Shock Test, MIL-STD-883E Method
2002.4, US Dept. of Defense, 2004.
Donald R. Ask eland, The science and engineering of materials, 1st
edn,Taipei, Kai Fa, 1985, ch. 6, pp. 126-127.
Trimmer, W.S.N, Microrobots and Micromechanical Systems, Sensors
and Actuators vol.19 no.3, pp. 267-287, 1989.
M. Elwenspoek, R. Wiegerink, Mechanical Microsensors,
Germany,Springer, 2001.
Tai-Ran Hsu, MEMS & Microsystems Design and
Manufacture,international edition 2002, Singapore, McGraw-Hill, pp.
157-159.
 Thanks
for your attention