ceng4480 a1

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Nao-NEX GEN...project...!!!!

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Sensors (v.1c) 1

JANGAM RAKESH KUMAR

SNIGDHA ROYSANJAY KALKAREPRIYA ANAMIKANEHA

Sensors (v.1c) 2

CENG4480_A1Sensors

Sensing the real world

Sensors (v.1c) 3

Sensors

Motion (Orientation/inclination )sensorsForce/pressure/strainPositionTemperature and humidityRotary positionLight and magnetic field sensors

Sensors (v.1c) 4

Motion (Orientation/inclination sensors

Acceleration GyroscopeCompassTilt Sensor

Sensors (v.1c) 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)

Sensors (v.1c) 6

ADXL78 (from Analog Device http://www.analog.com/UploadedFiles/Data_Sheets/ADXL78.pdf )Mass spring type (output acceleration in G)Measure the capacitance to create output

Sensors (v.1c) 7

ADXL330 accelerometer for three (X,Y,Z ) directions http://www.analog.com/UploadedFiles/Data_Sheets/ADXL330.pdf

3D

Sensors (v.1c) 8

2D translational accelerometerMX2125

Gas pocket typeWhen the sensor

moves, the temperatures of the 4 sensors are used to evaluate the 2D accelerations

Sensors (v.1c) 9

Accelerometer demo:orientation sensing

Self-balance RobotSensor demo

Sensors (v.1c) 10

Accelerometer demo :Tilt sensing demo

Tilt sensing demo

Sensors (v.1c) 11

Gyroscopes

Gyroscope Measure rotational angle

Rate 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.

Gyroscope

Sensors (v.1c) 12

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

Gyroscope to measure Rational acceleration ADXRS401

Sensors (v.1c) 13

Compass-- the Philips KMZ51 magnetic field sensor

50/60Hz (high) operation, a jitter of around 1.5°

Sensors (v.1c) 14

Rate gyroscope demo

Using Gyroscope compass for virtual reality application in an iphone

Sensors (v.1c) 15

Application of motion sensorsSelf balancing robot

by Kelvin Ko http://hk.youtube.com/watch?v=2u-EO2FDFG0

20cm

20cm

35cm35cm

Motion sensors: gyroscope and accelerometer

Sensors (v.1c) 16

Complementary filterComplementary filter

Since Since

Combine two sensors to find outputCombine two sensors to find output

1616

Sensors (v.1c) 17

Complementary filterComplementary filterθθ=rotation angle, =rotation angle, =filter time constant, s=laplace =filter time constant, s=laplace operator operator http://en.wikipedia.org/wiki/Low-pass_filter

1717

Sensors (v.1c) 18

Self Balanced robot using Self Balanced robot using complementary filtercomplementary filter

1818

Sensors (v.1c) 19

Tilt Sensor by OMRON

Detect tilting 35 ~ 65 degrees in right-and-left inclination

Sensors (v.1c) 20

Force/pressure/strain

Force-sensitive resistor (FSR)Strain gaugeFlexionAir pressure

Sensors (v.1c) 21

Force Sensing Resistors

FSR402

Sensors (v.1c) 22

Force Sensing Resistor Demo

Sensors (v.1c) 23

Application for a walking robot

Walking robot

Sensors (v.1c) 24

Application of force sensing resistance sensors to balance a walking robot

Balancing Floor tilled rightupper leg bend left

Floor tilled leftupper leg bend rightNeutral position

Four sensors under the foot

Sensors (v.1c) 25

Four Force sensors under the foot

D

Sensors (v.1c) 26

The Nao robot uses force feedback at its feet

Sensors (v.1c) 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.

Sensors (v.1c) 28

Single element strain gauge

sensitive to temperature change.

resistance gauge unstrainedR

gauge theof length Lfactor, gauge strainG and G for

4424220

L

L

R

R

L

LGVb

R

RVb

RR

RV

RR

R

R

RVV bb

Vb

R

R R

Gauge=R+Rgauge

load

rodV0

Sensors (v.1c) 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.

L

LGV

R

RV

RRRR

RR

RRRR

RRVV bbb 2

20

b1=R-Rt2=R+ R

b2=R-R t1=R+RVb

t1 t2

b1 b2

rod

load

V0

Sensors (v.1c) 30

Flexion (bend) sensors

resistance: 10 KΩ (0°); 30-40 KΩ (90°) /

Sensors (v.1c) 31

Felixon resistance Demo

Sensors (v.1c) 32

Air pressure sensor

Measure up to 150 psi (pressure per square inch ).

Sensors (v.1c) 33

Position sensors

Infra-red range sensorLinear and Rotary position sensors

Sensors (v.1c) 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.

Sensors (v.1c) 35

IR radar using the Sharp range detector

Sensors (v.1c) 36

Position sensors, from[1]

Rotary Linear

Optical shaft encoder

Sensors (v.1c) 37

Magnetic rotary encoder)

non touch sensing

Sensors (v.1c) 38

Optical rotary encoder)

The light received (on or off) will tell the rotation angle)

3 light emitters

3 light receivers

Rotation shaft

Light paths

http://www.youtube.com/watch?v=RuIislTGOwA

Crank shaft sensor

Sensors (v.1c) 39

Temperature and humidity

Temperaturehumidity

Sensors (v.1c) 40

Temperature sensorsLM135/235/335 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

Sensors (v.1c) 41

Application note (connecting to an ADC e.g. ADC0820 or ADC0801)

Sensors (v.1c) 42

Capacitive Atmospheric Humidity Sensor

BCcomponents 2322 691 90001 10-90%RH Dc

Sensors (v.1c) 43

Leaf Sensor Alerts When Plants Are Thirsty

Sensors (v.1c) 44

TSL250, TSL251, TSL252LIGHT-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.

Sensors (v.1c) 45

Cadmium Sulfoselenide (CdS) Photoconductive Photocells

Light sensing using CdS

Sensors (v.1c) 46

Hall effect Sensors for sensing magnetic flux“B field”, see:

Sensors (v.1c) 47

Application on Magnetic levitation 磁懸浮

Magnetic levitation Train Model 磁懸浮火車

frog levitation

Sensors (v.1c) 48

Hall effect sensors and brushless DC motors

Brushless DC motor

Is it using Hall effect sensor? Don't known.

Sensors (v.1c) 49

Novel sensors

Kinect /

Sensors (v.1c) 50

Many KINECT DIY projects

Sensors (v.1c) 51

Control systemsExample: A temperature control

system

Sensors (v.1c) 52

Control example: Temperature control system

Temp.Sensor A/D

CPU

D/APulse Width modulation

& solid state relay

Heater

Timer

Sample&

Hold

Digital controlcircuit

Instrum. amp.

Water tank

computer

Sensors (v.1c) 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).

Treq

Undershoot

Overshoot

Time

TempOn-off control result

Steady state error

Sensors (v.1c) 54

Temperature control method 2 : Proportional-integral-differential (PID) temperature control (good)

Init. (set required temperature Treq)

Loop forever{ get temperature T from sensor, e=T - Treq

then Tw =e*G*{Kp+Kd*[d(e)/dt] +Ki*e dt } else

} //G,Kp,Kd,Ki can be adjusted by user

Tw

Tw

Proportional, differential, integral

Sensors (v.1c) 55

PID block diagram

                                                                                                      

Figure 1 - Parallel PID block diagram

Kd

Ki

Kp

Sensors (v.1c) 56

PID control using pulse width modulation PWM

Fixed period and fixed number of pulses

Tw (depends on e )

Treq

PID control resultof method 2

On-off control: oscillates and unstable

Time

Temperature

Time

Sensors (v.1c) 57

Summary

Studied the characteristics of various sensors

and their applications

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