experimental verification of three-degree-of-freedom
TRANSCRIPT
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Akira HeyaKatsuhiro Hirata
Osaka University, Japan
Experimental Verification of Three-Degree-of-Freedom Electromagnetic
Actuator for Image Stabilization
19th International Symposium on Electromagnetic Fields in Mechatronics, Electrical and Electronic Engineering29-31 August 2019, “Prouvé” Congress Center Nancy – FRANCE
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Outline
Introduction
Proposed 3DOF actuator
Experimental verification
Conclusion
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Introduction
Environment recognition for autonomous systemusing camera
Phantom 4 (DJI Co., Ltd.) ibuki (Nakata et al., 2018)
Recognition accuracy deteriorations due to vibrations
Development of small robotic eye which has high kinematical performance
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Lens for camera Image sensor
Relationship of eye and camera
Lens-unit-swing system
Consists of lens (crystalline lens) and image sensor (retina)
Application of 3DOF actuator for downsizing
AdvantageCorrect wide range around 3-axis
DisadvantageIncrease in size and weight
Crystalline lens RetinaCrystalline lens Retina
Lens for camera Image sensor
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Experimental verification of proposed 3DOF actuator
Conventional Proposed*
3DOF actuator
Wang et al., 2003 Nishiura et al., 2016
* A. Heya et al., “Dynamic Analysis of High-Speed Three-Degree-of –Freedom Electromagnetic Actuator for Image Stabilization”, IEEE Transactions on Magnetics, Vol. 53, No. 11, 2706942, 2017
ApplicationRobot wrist, machine tool etc.
RequirementHigh torque, wide-angle drive
Large in sizeComplicated control device
ApplicationImage stabilizationfor eye system
RequirementSmall sizeHigh responsivenessSimple control device
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Contents
Introduction
Proposed 3DOF actuator
Experimental verification
Conclusion
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Based on a MM type VCM
Size:Φ28×25 mm (Magnetic circuit part)
About human’s eye size
Basic structure
X/Y-axis Z-axis
Cover
Bass plate
Coil
Rotor
Support parts
Outeryoke
Spherical bearing
Permanentmagnet
Mover
Rotor and bearing
Movable range
X : ±25 deg.
Y : ±25 deg.
Z : ±5 deg.
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X
Y
Z
B
FI
SN
SN
Rotation around X/Y-axis
XY
Z
B
FI
SN
N NS S
CoilLorentz force
Outer yoke A
Rotation around Z-axis
Operating principle
Controlled by 3-phase : simple control system
Outer yoke B
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z
y xX
Magnetic circuit
Magnetic path of the proposed actuator
xy
z
z
x
Magnetization
Reduction of magnetic flux leakage from 3-D structure
Detent torque works as magnetic spring
Y
Z
Y X
Z
X
Z
Outer yoke A
Outer yoke BOuter yoke B
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Contents
Introduction
Proposed 3DOF actuator
Experimental verification
Conclusion
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Prototype
Overview
Coil for driving around X/Y-axis
Side view
Overview
Base plate
Coil for driving around Z-axis
Supportparts
Top view
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Overview
Outer yoke A
Single coil for driving around X/Y-axis
Yoke
Rotor
20 mm
Permanentmagnet (Br = 1.3 T)Overview
Prototype
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Without the coil Aand rotor
Overview Except for the support parts
Outer yoke B
Overview
Prototype
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Operating verification
Experimental setup
• H-bridge circuit×3 (MAX14870, Maxim Integrated corp.)
• PWM frequency : 20 kHz
• Input voltage: 12 V
mbedLPC1768
(ARM Cortex-M3)
H-bridge driver
X-axis
Y-axis
Z-axis
Micro computer
System configuration for drivingProposed actuator
×3
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動作検証
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Torque characteristics
Experimental setup
Rotation around the X-axis Rotation around the Z-axis
Force sensor(MAF-3, WACOH-TECH Co.)Servo motor
Servo motor
Torque sensor(TCF02N, Tohnichi Co.)
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Measured results
Rotation around the X-axis Rotation around the Z-axis
Generated torques in each axis
-6
-4
-2
0
2
4
6
-25 -20 -15 -10 -5 0 5 10 15 20 25
Dete
nt
torq
ue [
mN
m]
Angle [deg.]
-6
-4
-2
0
2
4
6
-5 -4 -3 -2 -1 0 1 2 3 4 5
Dete
nt
torq
ue [
mN
m]
Angle [deg.]
02468
101214
To
rqu
e co
nst
an
t
[mN
m/A
]
05
101520253035
To
rqu
e co
nst
an
t
[mN
m/A
]
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Frequency characteristics
Ratio of input voltage and amplitude
Rotation around the X-axis Rotation around the Z-axis
Laser displacement sensor(LK-G35, KEYENCE Co.)
Multi functiongenerator
Bipolar amplifier
3DOF actuator
Voltage
Sine wave
System configuration
Linear stage
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Operating verification
Rotation around the X-axis Rotation around the Z-axis
0
2
4
6
8
10
12
0 10 20 30 40 50 60 70 80 90 100
Gain
[d
eg./
V]
Frequency [Hz]
0
1
2
3
0 10 20 30 40 50 60 70 80 90 100
Gain
[d
eg./
V]
Frequency [Hz]
Measured results
Proposed actuator can be drivenover wide frequency range
* Speed and Accuracy of Saccadic Eye Movements : Characteristics of Impulse Variability in the Oculomotor SystemRichard A. Abrams , David E. Meyer and Sylvan Kornblum
Max. angular acceleration: 60.2 × 104 [deg./s2]
Human’s eye motion*: 4.4 × 104 [deg./s2]
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Conclusion
Experimental verification
• Operating verification using prototype
• Torque generation by proposed principle
• Driving over wide frequency range
Future work
Proposal of Attitude sensor-less control method
Proposed magnetic structure and operating principle are valid