Ch 2 Kinematics
l
:
l
l
- 1 -
example)
l
-->
l
- 2 -
positive angles being counterclockwise
- 3 -
- 4 -
- 5 -
Rehabilitation Lab
Goniometer
What is a Goniometer?
Rehabilitation Lab
Goniometers are essentially devices that are used in angle
measurement.
Goniometers
Goniometer
Rehabilitation Lab
동영상
Features
Rehabilitation Lab
장점
Ø
간단한 이용방법으로 측정 가능 (임상, 실험등에서)
단점
Ø
정확한 데이터를 확보하기 어려움
Rehabilitation Lab
Potentiometer를 이용한 Goniometer
Potentiometer
Rehabilitation Lab
Potentiometer
(가변저항)
동영상
Rehabilitation Lab
Rehabilitation Lab
Strain gauge를 이용한 Goniometer
Biometrics Goniometer
Rehabilitation Lab
Biometrics Goniometer
Rehabilitation Lab
Joint
Amax
Amin
B
C
D
E
SG65
Wrist
65
30
55
18
54
20
SG110
Elbow or ankle
110
70
60
18
54
20
SG110/A
Ankle
110
70
60
18
18
54
SG150
Knee or hip
150
100
70
18
54
20
SG150/B
Back
150
50
120
18
54
20
Q110
Neck
110
70
60
18
54
20
Q150
Forearm
170
115
70
18
54
20
F35
Finger (DIP, PIP, MCP
) or toe
35
30
18
8
15
8
Transducer type : Strain gauge
Measuring Range : ±150°
Accuracy : ± 2º measured over a range of ± 90º
Temperature zero drift : 0.15 degrees angle / ºC
Strain gauge
Rehabilitation Lab
Strain
Ø
물체에 힘이 작용했을 때 물체의 변형 정도
Strain
Rehabilitation Lab
V=입력저항
G=출력전압
R1~R3=고정 저항
R4=Strain gauge저항치
영상
Rehabilitation Lab
Rehabilitation Lab
Magnetic encoder를 이용한 Goniometer
Vernier Goniometer
Rehabilitation Lab
센서에 metal dial 존재
센서 내부 magnet이 metal dial과 회전
magnetic encoder를 통해 전압 값 수집
Magnetic encoder
Rehabilitation Lab
자석의 회전에 따라 N극 S극 변화
Ø
이를 신호로 변화하여 위치 정보 출력
영상
Rehabilitation Lab
Digital goniometer with laser alignment
Rehabilitation Lab
cf) Gyrosensors, Tilt sensors, Magnetic sensors
- 6 -
Accelerometer
Contents
u What is the accelerometer?
ü Definition
ü Theory
uType of accelerometer
ü Consideration
u Data-sheet
ü MMA7260Q
u Application example
u
What is the accelerometer?
ü 이동하는 물체의 가속도나 충격의 세기를 측정
ü 기본 원리
: 물체가 힘을 받아 속도가 변하는 운동을 할 때 관성에 의해 센서 내부에
있는 mass의 위치가 변하는 것을 이용
u Type of accelerometer
ü 가속도계 선택 시 고려사항
감
도 (Sensitivity)
가속도의 주파수 영역
질 량 (Mass)
온 도 (Temperature)
Strain gauge type
u MMA7260Q (Capacitive transducer type)
ü 원리
• 극판의 거리에 반비례
+++++
-----
• 극판의 넓이에 비례
u MMA7260Q
ü 원리
Capacitance change à detect by Wheatstone bridge
u Wheatstone bridge
u MMA7260Q
ü 특징
• Selectable Sensitivity (1.5g / 2g / 4g / 6g)
• Low cost
• Sleep mode
• 6mm x 6mm x 1.45mm
u Application example
ü Scene change in acc in cell-phone
ü MEMS Accelerometer with LED bar display. Car Test
ü WeeWheel, Race with your phone's accelerometer!_
Gyro-sensor
What is a gyroscope?
• Basic theory
– Principle of conservation of angular momentum
– Every rotating object tends to maintain its plane of
rotation (Coriolis effect)
v
r
L = r ´ p = r ´ mv
2
= r ´ mrw = mr ´ w
= I ´w
What is a gyroscope?
• Device
– for measuring or maintaining orientation
What is a gyroscope?
The resistance to external angular rotation
µw
2
precession (skip)
Vibrating structure gyroscope
•
Halteres /hæltɪəriːz/ flap up and down as the wings do
•
Every vibrating object tends to maintain its plane of vibration (Coriolis
effect).
•
If the body of the insect changes direction in flight, the vibrating
halteres thus exert a force on the body. The insect detects this force
with sensory organs
•
Halteres thus act as a balancing and guidance system
haltere
principle
Piezoelectric Ceramic-rod
gyroscope
• CG-L43
• Size (mm) : 8x16x5
• Maximum detectable angular rate (deg/sec) : ±90
• CG-L53
By Nec Tokin
• Size : 6x10x2.5
• Maximum detectable angular rate (deg/sec) : ±90
• Features
• Miniature size
• High-speed response
• Magnetic field proof
• Application
• Image stabilizing system on camcorder, camera and binocular
• Stability control of radio-controlled helicopter
• Input equipment (mouse etc.)
Test experiment
l movie cameras with film
l film size (8-mm, 16mm, 35mm, 70mm) -- 16mm is the most popular
l ASA rate: the speed (sensitivity) of the film -- 100, 200, 400 (common)
l exposure time = 1/ (frame rate * factor)
- 7 -
l fixed frame rate: commonly 60 fields/s (sometimes 50 fields/s)
l CCD (charge-coupled device) for imaging
l electronic shutter control for the elimination of spatial blurring
l commercial systems: Vicon, Motion Analysis, Peak Performance
- 8 -
l Infrared lights on anatomical landmarks (Selspot, Watsmart)
l LED lights
- 9 -
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