Design and Simulation of a MEMS High G Inertial Impact Sensor

1
Design and Simulation of a MEMSHigh 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 [phone] Ext.31934, Email
  anitawu.wlh_at_msa.hinet.net
• 2Department of Mechanical and Mechatronic
  Engineering, National Taiwan Ocean University
• 2, Pei-Ning Road, Keelung, Taiwan.
• Speaker Jing-Wen Shih

2
Outline

• Introduction
• The major goal of Inertial impact sensor
• The micro impact sensor proposed in this study
• Simulation
• Conclusion
• Reference

3
Introduction

• Inertial sensors have been extensively utilized
  in science like inertial navigation systems and
  airbag triggers .
• For high G(gt300G) applications. Reaction times
  for conventional mechanical type impact sensors
  are not fast enough.

4
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.

5
Conventional inertial impact sensor

• (a)cantilever beam type
• (b)axial spring type

6
MDS System trigger

• MDS Mass- Damper- Spring Dynamic

7

• Proof mass expressed by dynamic equation lamped
  system

8

• Use Laplace transformation to the second order
  function for acceleration mass

9
The micro impact sensor proposed in this study
10
To evaluate system reaction time, 4 different
arrangements of spring and proof mass were
tested.
11
The proof mass scale and coil number of the sensor
12
Simulation

• Displacement versus applied forces for each sensor

13
The response time of the micro-sensor
14
Proof mass increases from 0.62 to 1.0, and the
spring constant remains unchanged, the reaction
time is decreased.
15
Minimum G values for the sensors to be triggered
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Reducing the spring constant, and retaining the
proof mass, the reaction time decreased and the
trigger G value decreased for sensors
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Minimum G values for the sensors to be triggered
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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.

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Conclusion

• This proposed impact sensor is intended for use
  at 8,00021,000G. 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.

20
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 Aphysical, vol. 100, Issue 1, pp.10-17
  , 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.

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• Thanks for your attention