Sensors and Sensor NetworksSensor and Actuator A sensor is a device that measures a physical...
Transcript of Sensors and Sensor NetworksSensor and Actuator A sensor is a device that measures a physical...
Lesson 3
Sensors and Sensor Networks
What are sensors and what are they for?
Various sensors and their features
What are sensor networks & their interconnections?
Sensor network technologies & applications
Sensor and Actuator A sensor is a device that measures a physical quantity and
converts it into a signal which can be read by an observer
or by an instrument. (Wikipedia)
An actuator is a device for moving/controlling a mechanism/system,
or generate some output, e.g., motor, LED, buzzer, speaker, etc.
Sensors and actuators are bridges between real and digital worlds
Sensor
Input Signal Output Signal
Various Sensors
Phidgetsセンサー
Moteセンサー
Force sensor Touch sensor
Vib. sensorMotion sensor
Solar Cell
Digital Infrared Ranging
Compass
Touch Switch
Pressure Switch
Limit Switch
Magnetic Reed Switch
Magnetic Sensor
Miniature Polaroid Sensor
Polaroid Sensor Board
Piezo Ultrasonic Transducers
Pyroelectric Detector
Thyristor
Gas Sensor
Gieger-MullerRadiation Sensor
Piezo Bend Sensor
Resistive Bend Sensors
Mechanical Tilt Sensors
Pendulum Resistive Tilt Sensors
CDS Cell Resistive Light Sensor
Hall EffectMagnetic Field
Sensors
Compass
IRDA Transceiver
IR Amplifier Sensor
IR ModulatorReceiverLite-On IR
Remote Receiver
Radio ShackRemote Receiver
IR Sensor w/lens
GyroAccelerometer
IR ReflectionSensor
IR Pin Diode
UV Detector
Metal Detector
General Ubiquitous System Model
Sensors
Actuators
人人体物体器具空間環境
ユビキタス
情報自動な取得、保存、処理、管理、分析、判断、使用、など
Multimedia Information
Comfortable Services
Contexts
Context-Aware
A ubiquitous/pervasive/AmI/CPS system can be regarded as a special
kind of information systems which use sensors to acquire various
information (of called context), process the contextual information,
and then take some responses through actuators.
IntelligentProcessing
Sensing & Action(Sensor Network)
Real/Physical World
Types of Sensors Acoustic, sound, vibration
-- Microphone, geophone, seismometer, accelerometer, …
Automotive, transportation
-- Speedometer, map sensor, water sensor, parking sensor, …
Chemical
-- Sensing carbon, gas, hydrogen, oxygen, smoke, etc.
Electric, magnetic, radio
-- Hall effect, magnetometer, metal detector, telescope, …
Environment, weather, moisture, humidity
-- Leaf sensor, rain/snow gauge, pyranometer, …
Flow, fluid velocity
-- Air flow meter, flow sensor, water meter, …
Ionising radiation, subatomic particles
-- Cloud chamber, neutron detection, particle detector, …
Types of Sensors (Cont.)
Navigation instruments
-- Air speed indicator, depth gauge, gyroscope, turn coordinate, …
Position, angle, displacement, distance, speed, acceleration
-- Accelerometer, position sensor, tilt sensor, ultrasonic sensor, …
Optical, light, imaging
-- Colorimeter, electro-optical sensor, infra-red sensor, photodiode, …
Pressure
-- Barometer, boost gauge, pressure gauge, tactile sensor, …
Force, density, level
-- Force gauge, level sensor, load cell, hydrometer, …
Thermal, heat, temperature
-- Heat sensor, radiometer, thermometer, thermistor, …
Proximity, presence
-- Motion detector, occupancy sensor, touch switch, ...
A list of various kinds of sensors in Wikipedia
Sensor Performance Range
maximum and minimum values that can be measured
Resolution or discrimination smallest discernible change in the measured value
Linearity
maximum deviation from a ‘straight-line’ response
Sensitivity
a measure of the change produced at the output for a given change
Error – Accuracy/Precision difference betw. measured & actual values Random/System Errors
SystemError
Temperature Sensors Resistive Thermometers
- typical devices use platinum wire, linear but has poor sensitivity
Thermistors
- use materials with a high thermal coefficient, sensitive, highly non-linear
pn junctions
- a semiconductor device, linear, easy to use, limited range (-50C to 150 C)
Thermometer Thermistor pn junction
Force Sensors Strain gauge
- stretching in one direction increases the resistance of the device,
while stretching in the other direction has little effect
- can be bonded to a surface to measure strain
- used within load cells and pressure sensors
A strain gauge
Direction of sensitivity
A force sensor videoPressure sensing principle
Motion Sensors
Motion sensors measure quantities such as velocity and acceleration
can be obtained by differentiating displacement
differentiation tends to amplify high-frequency noise
Alternatively can be measured directly
some sensors give velocity directly
e.g. measuring frequency of pulses in the counting techniques described earlier gives speed rather than position
some sensors give acceleration directly
e.g. accelerometers usually measure the force on a mass
Accelerometer Principles of Motion Sensing
Acceleration Sensor
Sound Sensors
Microphones
a number of forms are available
e.g. carbon (resistive), capacitive, piezoelectric and moving-coil microphones
moving-coil devices use a magnet and a coil
Ultrasonic Sensor
Ultrasonic sensors are used for position measurements
Sound waves emitted are in the range of 2-13 MHz
Sound Navigation And Ranging (SONAR)
Radio Detection And Ranging (RADAR) –ELECTROMAGNETIC WAVES !!
15° - 20°
Infrared Source IR Detector
CO2 Gas Sensor
CO2 sensor measures gaseous CO2 levels in an environment
Measures CO2 levels in the range of 0-5000 ppm
Monitors how much infrared radiation is absorbed by CO2
molecules
Biosensors A biosensor is an analytical device for the detection of an analyte
that combines a biological component with a physicochemical
detector component. (Wikipedia)
Health check, environment monitoring, food analysis, …
Incorporation of a biomolecule in order to detect something
Species to be detected (analyte)
Filter Recognition Layer
Transducer Electronics Signal
Recognition Layer
Electronic Tongue using Biosensors
Taste cell
Nerve cell
Taste compounds
Electric
responses
Brain
Taste
reception
Biological taste system
Artificial liquid system - electronic tongue
Sensor
responses ComputerSensor
arrayPattern
recognition
Y. Vlasov, A. Legin, A. Rudnitskaya, Anal. Bioanal. Chem. 2002, 373, 136.
Nanosensors
Nanosensors are any biological, chemical, or sugery sensory points
used to convey information about nanoparticles to macroscopic world.
Their uses mainly include various medicinal purposes and as gateways
to build other nanoproducts, such as computer chips that work at
nanoscale and nanorobots. (Wikipedia)
Medicinal uses of nanosensors to accurately identify particular cells
or places in the body.
Using nanosensors to build smaller integrated circuits, as well as
incorporating them in other chip/devices
Nanosesnors are new, ongoing research,
potential huge applications
MEMS and NEMS MEMS (Micro-Electro-Mechanical System) is the technology of
very small mechanical devices driven by electricity. (Wikipedia)
Range from 1 to 1000 micrometres in size (i.e. 0.001 to 1 mm)
Micromachines (in Japan), or Micro Systems Technology - MST (Europe)
NEMS (Nano-Electro-Mechanical System), similar but smaller (<100nm)
MEMS perform 2 basic types of functions: sensors or actuators.
- both act as transducers converting one signal into another.
MEMS actuators: electrical signal
physical phenomena to move or control mechanisms.
MEMS Sensors work in reverse to actuators
~ 1mm
MEMS and NEMS (cont.)
MEMS comprising mechanical and discrete electronic components
MEMS design is different from macro devices
MEMS design are based upon Silicon IC chips design
Micro-actuators: micro-motor, micro-mirror, micro-fluid pump, etc.
Micro-sensors: micro-accelerometer, micro-gyroscope, etc.
Electrostaticmotor
Hinge
Actuator Gyroscope
MEMS Gyroscope Chip
Video for Introduction to MEMS
A gyroscope is a device for measuring or maintaining orientation
Popular Sensors in Smart Phones
Android Sensor Java Development APIs
Sensors in Automotive Applications
Suspension Systems
Position Sensing
Chassis height
Electronic Power Steering
Position Sensing
Motor Commutation
Current Sensing
Safety Systems
Airbag Diagnostics & Control
Occupant Sensing
ABS/Traction - Wheel Speed Sensing
Convenience Systems
Door lock Position Sensing
Window Position/Speed Sensing
Window/Sunroof Direction
Sensing for anti-pinch
Seating Systems
Various Contactless Switches
Motor Controllers/Drivers
Wiper Systems
LCD screens
Powertrain Applications
Cam/Crank Sensors
Transmission Speed
Sensors
Throttle Position Sensors
EGR Valve Position
Sensors
Valve Position Sensors
Current Sensing
Google Self-Driving Car Project
Sensor Networks A sensor network (SN) is consisted of multiple interconnected sensors.
A wireless sensor network (WSN) consists of spatially distributed
autonomous sensors (called sensor nodes) to cooperatively monitor
physical or environmental conditions Sensors + Wireless Networks
San Fransisco’s Moscone Center equipped with sensor network
Traditional Networks vs WSN
An Introduction Video about Wireless Sensor Networks
Sensor Nodes
A sensor node, also called a mote in North America, is a WSN node that is capable of performing some processing, gathering sensory information and communicating with other connected nodes in the WSN.
Examples for Wireless Sensor Nodes
MICA Mote
Rene Mote
weC Mote
Dot Mote
Laser diodeIII-V process
Passive CCR comm.MEMS/polysilicon
SensorMEMS/bulk, surface, ...
Analog I/O, DSP, ControlCOTS CMOS
Solar cellCMOS or III-V
Thick film batterySol/gel V2O5
Power capacitorMulti-layer ceramic
1-2 mm
Example: Berkeley Motes, Smart Dust
• 4 KB RAM, 4 MHz CPU• 19.2 Kbps, 12m
Sensors in a Berkeley Mote
General Features of Sensor Node
Small Size : few mm to a few inches
Limited processing and communication
MHz clock, MB flash, KB RAM, 100’s Kbps (wireless) bandwidth
Limited power (MICA: 7-10 days at full blast)
Failure prone nodes and links (due to deployment, fab, wireless medium, etc.)
But easy to manufacture and deploy in large numbers
Need to offset this with scalable and fault-tolerant OS’s and protocols
Sensor-node Operating System
Issues
Size of code and run-time memory footprint
Embedded System OS’s inapplicable: > 100KB ROM
Workload characteristics
Continuous ? Bursty ?
Application diversity
Want to reuse sensor nodes
Tasks and processes
Scheduling, hard and soft real-time
Power consumption
Communication
Representative OS TinyOS, Contiki, NanoPK, LiteOS
TinyOS Layers and Functions
RFM
Radio byte
Radio Packet
i2c
Tempphoto
Messaging Layer
clocksbit
byte
packet
Routing Layer
sensing applicationapplication
HW
SW
ADC
messaging
routing
TinyOS Language and Size
0
500
1000
1500
2000
2500
3000
3500
Byte
s
InterruptsMessage DispatchInitilizationC-RuntimeLight SensorClockSchedulerLed ControlMessaging LayerPacket LayerRadio InterfaceRouting ApplicationRadio Byte Encoder
Scheduler:
144 Bytes code
Totals:
3430 Bytes code
226 Bytes data
• Event-driven execution (reactive mote)
• Use a variant of language C called NesC
Limited power they can harvest or store
Ability to withstand harsh environmental conditions
Ability to cope with node failures
Mobility of nodes
Dynamic network topology
Communication failures
Heterogeneity of nodes
Large scale of deployment
Unattended operation
Nodes are scalable, only limited by bandwidth of gateway node
WSN Characteristics
Typical Multiple WSN Architecture
A sensor network normally constitutes a wireless ad-hoc network,
and each sensor supports a multi-hop routing algorithm where
nodes function as forwarders, relaying data packets to a base station.
WSN Topologies
Sensor Network System
Interface electronics, radio
and microcontroller
Soil moisture probe Senor
Node
Antenna
Gateway
Server
Internet
Communications barrier
Sensor field
Sensor Network System
Gateway
Server
Internet
Sensor fieldWatershed
Multiple Sensor Networks System
S
S
S
S
SS
S
SSS
S S
S
S
Sensor net
Internet
Access
Node
Storage
Distribution field of
phenomena that
can be detected
measured
Physical
Phenomena
User
Sensors that
detect event Sensors that
notify access
node
Sensor
net
Sensor
net
40
WSN System Issues
Applications
service
network
system
architecture
data mgmt
Monitoring & Managing Spaces and Things
Technologies
MEMS
sensingPower
Comm. uRobots
actuate
Miniature, low-power connections to the physical world
Proc
Store
WSN System Platforms
OS
Hardware
Application
Signal Proc.Detection
Power Supply
StorageNetworkingClassificationTracking
RoutingFiltering Transport
Link Layer
TimersTime Sync
SensorsMCU
Radio Storage
Scheduler
Storage
OTAP
Query Processing
Heap FilesIndicesDissemination
Interrupts
Arbiters Queues
ZigBee, 802.15.4, EnOcean, IETF PRL, etc
Time Sync
Sensor
router
– “the software”
– Network, Security &
Application layers
– Brand management
IEEE 802.15.4
– “the hardware”
– Physical & Media Access
Control layers
Wireless Sensor Network Standards IEEE 802.15.4 & ZigBee
PHY
868MHz / 915MHz / 2.4GHz
MAC
Network
Star / Mesh / Cluster-Tree
Security32- / 64- / 128-bit encryption
Application
API
ZigBeeAlliance
IEEE 802.15.4
Customer
Sensor Data Management
phenomena
sensors
observer
Observer interested in phenomena with certain tolerance
Accuracy, freshness, delay
Sensors sample the phenomena
Sensor Data Management
Determining spatio-temporal sampling schedule
Difficult to determine locally
Data aggregation
Interaction with routing
Network/Resource limitations
Congestion management
Load balancing
QoS/Realtime scheduling
Sensor Data Query
Sink
Select temp from
Fully aggregated queries Un-aggregated queries Partially aggregated queries
Sensing Information Fusion One sensor is (usually) not enough
- Noisy, limited accuracy, unreliable – failure, environment restriction, etc.
Sensor fusion - Combine readings from several sensors into a better one
Fusion Interpretation
Sensor 2
Sensor 3
Sensor N
Sensor 1
Sensing Perception
Preprocessing
Preprocessing
Preprocessing
Preprocessing
(1.10, 1.06) 1.08
(0.92, 0.96) 0.94
(0.30, 0.36) 0.33
(0.94, 0.96) 0.95
1.08+0.94+0.953 0.99
ObjIgnore 0.43
0.33?
Sensing Information Fusion
Preprocessing
- 'Cleanup’ the sensor readings before using them, e.g.,
noise reduction, re-calibration, unify the format, etc.
Data Fusion
- Combine data from different sources
- Measurements from different sensors
- Measurements from different positions
- Measurements from different times
Techniques that take into account uncertainties in data sources
- Discrete Bayesian methods
- Neural networks
- Kalman filtering
Sensor Web
Sensor Web - Wikipedia
Semantic Sensor Web
Sensor Web (Cont.)
Access the following websites to learn more about
various sensors, sensor networks, and their features,
technologies, applications, etc.
Sensor - Wikipedia
List of sensors - Wikipedia
MEMS – Wikipedia
Android Sensor Java Development APIs
Wireless sensor network – Wikipedia
TinyOS – Wikipedia
An Introduction Video about Wireless Sensor Networks
Others you like Important to get materials from Web!!
Homework