Monitoring and Control Flashcards
Sensor
Collects data about physical environment automatically
12 types of sensors :(
- light/UV (car park barrier system)
– temperature
– pressure
– humidity (measure water content of soil)
– pH (measure the acidity of soil)
– gas sensors
– sound (burglar alarm systems)
– infrared (detect movement in burglar alarm)
– touch sensors
– (electro)magnetic field sensors
– proximity sensor ( in smartphones to switch off screen display when phone is held near to the ear)
Sensor advantage
More reliable than human because human may forget
Readings more accurate
Can be used in dangerous places where humans cant go
dont need human
24/7 as humans will get tired etc
Actions or warnings will happen immediately
Sensor disadvantage
Digital sensor need constant power source (passive sensor is fine)
If it malfunctions in a remote place user will not know
bad data if faulty
most need analogue to digital
Calibration
Need reference such as other sensor or physical reference (ruler)
Offset (like zero error)
Sensitivity (how much change in physical will it respond to)
Linearity (consistency of measurements over the entire range of measurements)
3 types of calibration
one point
two point
multi point
Use of one point calibration
to fix offset
take reading with sensor and compare to ideal
find offset and subtract from every value
Use of two point calibration
Fix offset and sensitivity
take 2 different readings on lower end and high end
compare to ideal
and use formula to correct each value
multi point calibration
performed using multiple readings
more accurate and helps with linearity
Monitoring system
Collect data and store it to analyze in future
Uses storage devices, sensors , graphing software
Examples of monitoring system
– environmental monitoring
○ monitoring water pollution
○ weather stations, use of sensors
○ temperature sensors to measure ambient temperature
○ pressure sensors to measure atmospheric pressure
○ humidity sensors to measure absolute and relative humidity
○ light sensors to measure sunlight
– environmental patients
Control system
Collect data and send to computer to analyze and take action
Uses sensor, microprocessor, actuator
Microprocessor
Electronic component that can perform similar functions to CPU
can also hold small amount of data in register
Adv/dis of microprocessor
Can be programmed to execute several different tasks
Small in size
can overheat
limit on size of data can hold
Actuator
Used to move/operate mechanisms or devices
Actuator types
○ linear
○ rotary
○ soft
○ hydraulic
○ pneumatic
○ electric
○ thermal
○ magnetic
○ mechanic
Examples of microprocessor controlled technology
– greenhouses
– central heating systems
– air conditioning systems
– burglar alarms
– control of traffic/pedestrian flow (including smart motorways)
– car park barriers
– traffic lights
– Wireless Sensor and Actuator Networks
– smart homes
