tài liệu viết về điều khiển vi cơ

1. Micro Cam Mechanism Based On
Electrostatic Comb-drive Actuators
*Authors: Pham Hong Phuc, Dinh Khac Toan,
Nguyen Tuan Khoa, Dang Bao Lam
*School of Mechanical Engineering, Hanoi University
of Science and Technology, Vietnam
3rd IFToMM International Symposium on
Robotics and Mechatronics
2 – 4 October 2013, Singapore

2. Outline
Configuration and Working Principle2
Fabrication4
Force Analysis33
Introduction31
5 Conclusion

3. Introduction
1
According to the
actuation method:
- Electrostatic
- Electromagnetic
- Electrothermal
- Piezoelectric
- SMA
- Other…
2
According to the
movement transmission
method:
- Solid-based
+ Sub-mechanisms
+ Flexure joints
+ Flexure structures
- Air-bearing
- Liquid-based
Micro Mechanism
Introduction Conf & W/Principle Force Analysis Fabrication Conclusion

4. Examples of Micro Mechanism
Introduction Conf & W/Principle Force Analysis Fabrication Conclusion
Fabricated by Sandia SUMMiT process
Drive a 100- m-diameter gear
Torque of at least 500 pN-m
Driving voltage ≤ 12V
Jae-Sung Park et al. (2001). Bent-Beam Electrothermal Actuators - Part II: Linear and Rotary
Microengines. J. of MicroElectroMechanical Sys., Vol. 10, No. 2, pp. 255-62.

5. Examples of Micro Mechanism
Introduction Conf & W/Principle Force Analysis Fabrication Conclusion
Fukui R. et al. (2001), Micro Robot Actuated by Rapid Deformation of
Piezoelectric Elements, 2001 Inter. Symposium on Micromechatronics
& Human Science, pp. 117-122.

6. Examples of Micro Mechanism
Introduction Conf & W/Principle Force Analysis Fabrication Conclusion
Kim C J et al. (1999), Design fabrication and
testing of a polysilicon microgripper,
Microstructures, Sensors, and Actuator, pp 99-
109.
Bazaz S.A. et al. (2011), Design, simulation and testing of
electrostatic SOI MUMPs based microgripper integrated with
capacitive contact sensor, Sensors and Actuator A, 167(1), pp
44-63.

7. Phuc Hong Pham, Dzung Viet Dao, Lam Bao Dang, Susumu Sugiyama, “Single mask, simple structure micro
rotational motor driven by electrostatic comb-drive actuators”, J. Micromech. Microeng., 22 (2012)
Introduction Conf & W/Principle Force Analysis Fabrication Conclusion
Micro Cam Mechanism (MCM)

8. Configuration and working principle of the MCM
Introduction Conf & W/Principle Force Analysis Fabrication Conclusion
 Fixed electrodes
 Movable parts
 Anti-reverse mechanisms
Movement-transmission mechanisms
Outer cam rim
Follower
Springs connected
to the follower
Spring-A connector
between the ECA beam
and ratchet rack
 Elastic point

9. Force analysis: Driving period
Force analysis of the MCM
Driving force :
Where:
3
2 4
4
f
d es el f f
F
F F F F F    
20
0
. . .
.es
nb
F V
g
 
 
2 2. .fF f m G 
3 3. .fF f m G 
. ( . )el p pF k d k i p g   
4 3
3
. . os . . osf a
EI
F f F c f h c
l
   
Fes
Ff3/4
tooth of the
driving ratchet
tooth of the
outerring
Driving
movement
Fel
Ff2
(1)
(2)
(3)
(4)
(5)
(6)
Introduction Conf & W/Principle Force Analysis Fabrication Conclusion

10. Force analysis: Driving period
Force analysis of the MCM
 
 
 
 
cos sin
and
cos 2 cos 2
R Q P Q
 
 
 Forces:
Where: 2 62 s fQ F F  
  '
5 5.sin or .f fF R F Q f 
6 . .f FF f m G 
 7 .sinfF P  
2 2 2.s s sF k y 
 atan f 
7' fQ Q F  
The condition for the driving force : 52 d fF F (7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
(15)
Introduction Conf & W/Principle Force Analysis Fabrication Conclusion

11. Force analysis: Driving period
 From equations (1) to (7), the driving voltage must be
satisfied a condition as presented below:
3 5
0 2 4
0
. ( . )
4 2
. . .
f f
p f f
F F
g k i p g F F
V
nb 
 
     
 
Where: Ff5 is determined by the equations from (8) to (15)
(17)3 5
0 2 4
min
0
. ( . )
4 2
. . .
f f
p f f
F F
g k i p g F F
V
nb 
 
     
 
Or:
(16)
Introduction Conf & W/Principle Force Analysis Fabrication Conclusion
Number of moved ratchet teeth Minimum driving voltage
i = 1 Vmin = 67.81 (V)
i = 2 Vmin = 84.64 (V)

12. Force analysis: Returning period
 Condition for the driving ratchet rack to go back to the initial
position: 1'' sQ F
Where:  2
1
'' ' .cos ' .sin 2
2
n el fQ Q F Q F F     
1 1. 14.22 ( )s sF k h N 
 Both i = 1 and i = 2
satisfies condition (21).
 To guarantee the
outer cam rim can
rotate, the minimum
driving voltage must
be Vmin = 67.81(V)
(21)
(22)
(23)
Introduction Conf & W/Principle Force Analysis Fabrication Conclusion

13. Simulation
a) Elastic point of the ECA beam b) Spring of the follower
Simulation results of structure stiffness
Introduction Conf & W/Principle Force Analysis Fabrication Conclusion

14. Fabrication process
Fabrication process
1. Preparation step
2. Lithography and
developing
processes
3. DRIE process
4.Vapor HF etching
process
Si layer (30µm)
SiO2 layer (4µm)
Si substrate
Photoresist layer
SiO2 layer
Fixed parts
Movable
parts
Si substrate
Introduction Conf & W/Principle Force Analysis Fabrication Conclusion

15. Fabricated MCM
SEM image of the MCM and its components
Introduction Conf & W/Principle Force Analysis Fabrication Conclusion

16. Performance of the MCM
Introduction Conf & W/Principle Force Analysis Fabrication Conclusion
Operation of the MCM

17. Angular velocity of the MCM
 In theory, the time for the cam rotates one round can be
expressed by:
740 37
(min)
60. . 60. . 3. .
z
t
i f i f i f
  
 The theoretical angular velocity of the cam can be
expressed below:
1 3. .
( )
37
i f
n rpm
t
 
(24)
(25)
Introduction Conf & W/Principle Force Analysis Fabrication Conclusion
Driving frequencies (Hz) Theoretical ang. Velocity (rpm)
10 1.62
20 3.24

18. Conclusion and Discussion
Design, fabrication and test showed that the mechanism performed
successfully. The MCM has run smoothly and achieved the follower
stroke of 160m with the driving voltage of 80V and 100V, respectively
In near future, measurement of loading force and angular velocity of
the MCM, improvement to reduce driving voltage and sliding
phenomenon will be carried out
In near future, the MCM would be applied in micro assembling or
fatigue testing systems.
Introduction Conf & W/Principle Force Analysis Fabrication Conclusion
The MCM with the flat-faced translating follower is developed from the
original Micro Rotational Motor (MRM)

19. Corresponding author: phuc.phamhong@hust.edu.vn
Thank you for attention!