Transcript Document 390497

Embedded Systems Development
and Applications
Terrence Mak
The Chinese University of Hong Kong
CENG4480 - 2014/15
Sensors
•
•
•
•
•
•
Motion (Orientation/inclination) sensors
Force/pressure/strain
Position
Temperature and humidity
Rotary position
Light and magnetic field sensors
2
Motion
•
•
•
•
Acceleration
Gyroscope
Compass
Tilt Sensor
Sensors (v.1c)
3
Accelerometer
http://en.wikipedia.org/wiki/Accelerometer
• Functions:
– Measure acceleration in one or more directions,
position can be deduced by integration.
– Orientation sensing : tilt sensor
– Vibration sensing
• Methods:
– Mass spring method ADXL78 (from Analog
Device )
– Air pocket method (MX2125)
4
5
ADXL78 (from Analog Device)
• Mass spring type (output acceleration in G)
• Measure the capacitance to create output
6
ADXL330
Accelerometer for three (X,Y,Z) directions
• 3D
7
2D Translational Accelerometer
MX2125 (from www.parallax.com)
• Gas pocket type
• When the sensor
moves, the
temperatures of
the 4 sensors are
used to evaluate
the 2D
accelerations
8
Accelerometer: Orientation Sensing
•
Sensor demo
http://www.youtube.com/watch?v=9NEiBDBXFEQ
9
10
Accelerometer: Tilt sensing demo
•
Tilt sensing demo
http://www.youtube.com/watch?v=C6uVrYz-j70
11
12
Sensors (v.1c)
13
Gyroscopes
http://en.wikipedia.org/wiki/Gyroscope
• Gyroscope
– Measure rotational angle
• Rate Gyroscope
Gyroscope
– measure the rate of rotation along 3-axes
of X
(pitch), Y (roll), and Z (yaw).
– Modern implementations are using
Microelectromechanical systems (MEMS)
technologies.
14
Gyroscope to measure Rational acceleration
ADXRS401 http://www.analog.com/UploadedFiles/Data_Sheets/ADXRS401.pdf
• FEATURES
– Complete rate gyroscope on a single chip Microelectromechanical systems (MEMS)
– Z-axis (yaw-rate) response
• APPLICATIONS
–
–
–
–
GPS navigation systems
Image stabilization
Inertial measurement units
Platform stabilization
15
16
Compass-- the Philips KMZ51 magnetic
field sensor
• 50/60Hz (high) operation, a jitter of around
1.5°
17
Rate gyroscope demo
•
Using Gyroscope compass for virtual reality application in an iphone
http://www.youtube.com/watch?v=VP4-wdMMLFo
18
Tilt Sensor by OMRON
http://rocky.digikey.com/WebLib/Omron%20Web%20Data/D6B.pdf
• Detect tilting 35 ~ 65 degrees in right-and-left
inclination
19
Force, Pressure and Strain
•
•
•
•
Force-sensitive resistor (FSR)
Strain gauge
Flexion
Air pressure
20
Force Sensing Resistors
http://www.interlinkelectronics.com/library/media/papers/pdf/fsrguide.pdf
• FSR402
Sensors (v.1c)
21
Force Sensing Resistor Demo
http://www.youtube.com/watch?v=LQ21lXr6egs
22
Application for a walking robot
• Walking robot
23
Application of force sensing resistance sensors to
balance a walking robot
• Balancing
Neutral position
Floor tilled left
upper leg bend right
Floor tilled right
upper leg bend left
Four sensors under the foot
24
Four Force sensors under the foot
25
Strain Gauge : Force sensors
http://www.meas-spec.com/myMeas/default/index.asp
• Piezoelectric crystal: produces a voltage that is
proportional to force applied
• Strain gauge: cemented on a rod. One end of the rod
is fixed, force is applied to the other end. The
resistance of the gauge will change with the force.
26
Sensors (v.1c)
27
Single element strain gauge
• sensitive to temperature change.
Vb
Gauge=R+R
R
gauge
rod
V0
R
R
load
æ R
æ DR ö
æ DR ö
æ G DL ö
R ö
V0 = Vb ç ÷ = Vb ç
÷ » Vb ç ÷ = Vb ç
÷
è 2R 2R + DR ø
è 4R + 2DR ø
è 4R ø
è4 L ø
DR
DL
for
= G
and G = strain gauge factor, L = length of the gauge
R
L
R = unstrained gauge resistance
28
Four-element (Wheatstone bridge)
strain gauge sensor,
• Four times more sensitive than single gauge system; not
sensitive to temperature change.
• All gauges have unstrained resistance R.
t1
t2
Vb
rod
t1=R+R
b2=R-R
V0
b1
b2
b1=R-R
t2=R+ R
load
æ
ö
æ 2DR ö
æ DL ö
R + DR
R - DR
V0 = Vb ç
÷ = Vb ç
÷ = Vb çG ÷
è R + DR + R - DR R + DR + R - DR ø
è 2R ø
è Lø
29
Flexion (bend) sensors
• Resistance
• 10 KΩ (0°)
• 30-40 KΩ (90°)
http://www.flexpoint.com/
http://www.jameco.com/wcsstore/Jameco/Products/ProdDS/150551.PDF
Sensors (v.1c)
30
Felixon resistance Demo
•
http://www.youtube.com/watch?v=m4E5SP7HCnk&feature=related
31
Air pressure sensor
• Measure up to 150 psi (pressure per square
inch).
32
Position sensors
• Infra-red range sensor
• Linear and Rotary position sensors
33
Infra-red Range detectors by SHARP (4 to 30cm)
• An emitter sends out light pulses. A small
linear CCD array receives reflected light.
• The distance corresponds to the triangle
formed.
Sensors (v.1c)
34
IR radar using the Sharp range detector
http://www.youtube.com/watch?v=tStBLAiQaC8&feature=related
35
Position sensors
• Rotary
Linear
• Optical shaft encoder
36
Magnetic rotary encoder
(http://www.renishaw.com/UserFiles/acrobat/UKEnglish/L-9517-9147.pdf)
• Non-touch sensing
37
Optical rotary encoder
(http://en.wikipedia.org/wiki/Rotary_encoder)
• The light received (on or off) will tell the
3 light receivers
rotation angle)
Light paths
Rotation shaft
3 light emitters
Crank shaft sensor
Sensors (v.1c)
38
http://www.youtube.com/watch?v=RuIislTGOwA
Temperature and humidity
• Temperature
• Humidity
Sensors (v.1c)
39
Temperature Sensors
http://www.national.com/pf/LM/LM135.html
•
•
•
•
•
•
•
•
Directly calibrated in °Kelvin
1°C initial accuracy available
Operates from 400 µA to 5 mA
Less than 1 Ohm dynamic impedance
Easily calibrated
Wide operating temperature range
200°C over range
Low cost
40
Application note
•
41
Leaf Sensor Alerts When Plants Are
Thirsty
http://www.youtube.com/watch?v=VM4X_fqPPco
Sensors (v.1c)
42
TSL250, TSL251, TSL252
LIGHT-TO-VOLTAGE OPTICAL SENSORS
http://focus.ti.com/general/docs/scproducts.jsp
• Light-to-voltage optical sensors, each combining a
photodiode and an amplifier (feedback resistor = 16
MW, 8 MW, and 2 MW respectively).
• The output voltage is directly proportional to the light
intensity on the photodiode.
43
Cadmium Sulfoselenide (CdS)
Photoconductive Photocells
http://faculty.uml.edu/aelbirt/16.480/pdvp5001.pdf
• Light sensing using CdS
44
•
Hall effect Sensors for sensing
magnetic flux “B field”
http://doc.semicon.toshiba.co.jp/noseek/us/td/td2frame.htm
45
Application on Magnetic levitation 磁懸浮
http://myweb.msoe.edu/~muthuswamy/pubs/DesignOfMagneticLevitationControllersUsingJacobiLinearizationFeedbackLinearizationAndSlidingMode.pdf
•
Magnetic levitation Train Model
磁懸浮火車
http://www.youtube.com/watch?v=TeS_U9qFg7Y
http://www.youtube.com/watch?v=XjjBqzilkIc
frog levitation
http://www.youtube.com/watch?v=A1vyB-O5i6E
46
Hall effect sensors and brushless DC
motors
• Brushless DC motor
•
•
http://dev.emcelettronica.com/files/u4/Brushless_DC_Motors_bldc_motor.jpg
• Is it using Hall effect sensor? Don't known.
http://www.youtube.com/watch?v=cm0h2Qf3upQ
http://www.youtube.com/watch?v=JmRkxZT4XhY
47
Novel sensors
• Kinect
http://www.ladyada.net/learn/diykinect/
http://www.youtube.com/watch?v=nvvQJxgykcU
http://www.youtube.com/watch?v=Mf44bWQr3jc
48
Many KINECT DIY
projects
•
http://www.youtube.com/watch?v=Brpu30vjCa4&feature=related
http://www.youtube.com/watch?v=3V-TGXFZbbA&feature=related
49
Sensors (v.1c)
50
Sensors (v.1c)
51
Sensors (v.1c)
52