The document discusses various types of sensors including motion sensors, force sensors, position sensors, temperature and humidity sensors, and light sensors. It provides examples of accelerometers, gyroscopes, strain gauges, flex sensors, temperature sensors, and optical sensors. It also discusses applications of sensors in areas like self-balancing robots, walking robots, and temperature control systems using PID control algorithms.

1. JANGAM RAKESH
KUMAR
SNIGDHA ROY
SANJAY KALKARE
PRIYA ANAMIKA
NEHA
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2. CENG4480_A1
Sensors
Sensing the real world
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3. Sensors
Motion (Orientation/inclination )sensors
Force/pressure/strain
Position
Temperature and humidity
Rotary position
Light and magnetic field sensors
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4. Motion (Orientation/inclination
sensors
Acceleration
Gyroscope
Compass
Tilt Sensor
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5. 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)
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6. ADXL78 (from Analog Device
http://www.analog.com/UploadedFiles/Data_Sheets/ADXL
)
Mass spring type (output acceleration in G)
Measure the capacitance to create output
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7. ADXL330 accelerometer for three (X,Y,Z ) directions
http://www.analog.com/UploadedFiles/Data_Sheets/ADXL330.pdf
3D
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8. 2D translational accelerometer
MX2125
Gas pocket type
When the sensor
moves, the
temperatures of
the 4 sensors are
used to evaluate
the 2D
accelerations
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9. Accelerometer demo:
orientation sensing
Self-balance Robot
Sensor demo
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10. Accelerometer demo :
Tilt sensing demo
Tilt sensing demo
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11. Gyroscopes
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.
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12. Gyroscope to measure Rational acceleration
ADXRS401
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 Sensors (v.1c) 12

13. Compass-- the Philips KMZ51
magnetic field sensor
50/60Hz (high) operation, a jitter of around
1.5°
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14. Rate gyroscope demo
Using Gyroscope compass for virtual reality application in an iphone
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15. Application of motion sensors
Self balancing robot
by Kelvin Ko Motion sensors:
http://hk.youtube.com/watch?v=2u-EO2FDFG0
gyroscope and
accelerometer
20cm
35cm
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16. Complementary filter
Since
Combine two sensors to find output
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17. Complementary filter
θ=rotation angle, τ=filter time constant, s=laplace
operator
http://en.wikipedia.org/wiki/Low-pass_filter
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18. Self Balanced robot using
complementary filter
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19. Tilt Sensor by OMRON
Detect tilting 35 ~ 65 degrees in right-and-
left inclination
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20. Force/pressure/strain
Force-sensitive resistor (FSR)
Strain gauge
Flexion
Air pressure
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21. Force Sensing Resistors
FSR402
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22. Force Sensing Resistor Demo
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23. Application for a walking robot
Walking robot
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24. Application of force sensing resistance
sensors to balance a walking robot
Balancing Floor tilled left Floor tilled right
Neutral position upper leg bend right upper leg bend left
Four sensors under the foot
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25. Four Force sensors under the foot
D
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26. The Nao robot uses force feedback at its feet
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27. Strain Gauge : Force sensors
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.
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28. Single element strain gauge
sensitive to temperature change.
Vb gauge
R Gauge=R+∆R rod
V0
R
R load
 R R   ∆R   ∆R   G ∆L 
V0 = Vb  −  = Vb   ≈ Vb  = Vb 
 2 R 2 R + ∆R   4 R + 2 ∆R   4R   4 L 
∆R ∆L
for =G and G = strain gauge factor, L = length of the gauge
R L
R = unstrained gauge resistance
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29. 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
b2=R-∆R t1=R+∆R rod
V0 b1 b2
t2=R+ ∆R b1=R-∆R load
 R + ∆R R − ∆R   2∆ R   ∆L 
V0 = Vb  −  = Vb   = Vb  G 
 R + ∆R + R − ∆R R + ∆R + R − ∆R   2R   L 
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30. Flexion (bend) sensors
resistance:
10 KΩ (0°);
30-40 KΩ (90°) /
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31. Felixon resistance Demo
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32. Air pressure sensor
Measure up to 150 psi (pressure per square
inch ).
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33. Position sensors
Infra-red range sensor
Linear and Rotary position sensors
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34. 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.
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35. IR radar using the Sharp range
detector
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36. Position sensors, from[1]
Rotary Linear
Optical shaft encoder
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37. Magnetic rotary encoder
)
non touch sensing
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38. Optical rotary encoder
)
The light received (on or off) will tell the
rotation angle) 3 light receivers
Light paths
Rotation shaft
3 light emitters
Crank shaft sensor
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http://www.youtube.com/watch?v=RuIislTGOwA

39. Temperature and humidity
Temperature
humidity
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40. Temperature sensors
LM135/235/335 features(from NS)
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
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41. Application note (connecting to an
ADC e.g. ADC0820 or ADC0801)
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42. Capacitive Atmospheric Humidity
Sensor
BCcomponents 2322 691 90001
10-90%RH Dc
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43. Leaf Sensor Alerts When Plants
Are Thirsty
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44. TSL250, TSL251, TSL252
LIGHT-TO-VOLTAGE OPTICAL SENSORS
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.
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45. Cadmium Sulfoselenide (CdS)
Photoconductive Photocells
Light sensing using CdS
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46. Hall effect Sensors for sensing
magnetic flux“B field”, see:
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47. Application on Magnetic levitation 磁懸浮
Magnetic levitation Train Model
磁懸浮火車
frog levitation Sensors (v.1c) 47

48. Hall effect sensors and brushless DC
motors
Brushless DC motor
Is it using Hall effect sensor? Don't known.
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49. Novel sensors
Kinect /
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50. Many KINECT
DIY projects
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51. Control systems
Example: A temperature control
system
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52. Control example: Temperature control system
computer
Digital control Timer
Water tank circuit
Temp. Sample
Sensor Instrum. A/D
amp. &
Hold
CPU
Pulse Width
Heater modulation D/A
& solid state relay
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53. Temperature control method 1: ON-Off (bang-bang)
control (poor)
Easy to implement, bad control result -- contains overshoot
undershot. Algorithm for on-off-control:
Loop forever: If (Tfrom_sensor > Treq required temperature)
then (heater off )
else (heater on).
Overshoot
Treq
Steady state error
Undershoot
Temp
On-off control result
Time
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54. Temperature control method 2 : Proportional-integral-
differential (PID) temperature control (good)
Init. (set required temperature Treq)
Loop forever{
get temperature T from sensor, Tw
e=T - Treq
then Tw =e*G*{Kp+Kd*[d(e)/dt] +Ki*∫e dt }
Proportional, differential, integral
else
} //G,Kp,Kd,Ki can be adjusted by user
Tw Sensors (v.1c) 54

55. PID block diagram
Kd
Kp
Figure 1 - Parallel PID block diagram
Ki
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56. PID control using pulse width
modulation PWM
Tw (depends on e )
Time
Fixed period and fixed number of pulses
Temperature On-off control: oscillates and unstable
Treq
PID control result
of method 2
Time
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57. Summary
Studied the characteristics of various
sensors
and their applications
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