Automated Systems PDF

4 Automated Systems Ch.4: Automated Systems Eng. Omar El Safty 1. Sensors Definition of a sensor: An input device used to measure the physical properties of the surrounding environment. Sensor...

4 Automated Systems Ch.4: Automated Systems Eng. Omar El Safty 1. Sensors Definition of a sensor: An input device used to measure the physical properties of the surrounding environment. Sensor Description Purpose: Measures temperature of the surroundings Example of uses: Temperature Monitors the temperature in a central heating system/greenhouse Monitors the temperature of a chemical process Checks whether the water in a kettle is boiling Purpose: Measures amount of water in a sample, for example soil Moisture Example of uses: Monitors the water levels in soil in a greenhouse Monitors the water levels in a food processing factory Purpose: Measures amount of water vapor of the surrounding air Humidity Example of uses: Monitors humidity levels in a greenhouse/building/factory Checks whether the air is dry enough in a spray-painting garage Purpose: Measures light brightness in an environment Example of uses: Light Monitors light intensity in automatic street lighting Monitors the brightness of the environment in greenhouse Automatically switches on a car's headlights when it gets dark 56 Ch.4: Automated Systems Eng. Omar El Safty Purpose: Detects motion by using invisible infra-red beam that is picked up by a Infra-red detector; if the beam is broken, then motion is detected (Motion) Example of uses: Detects motion in a room for a security system/burglar alarm system Detecting whether a person is approaching automatic doors Counts people entering/leaving a building Purpose: Measures the amount of pressure applied Example of uses: Pressure Detects intruders in a security system/burglar alarm system Checks the weight of a vehicle Monitors a process where gas pressure is important Purpose: Measures the acidity or alkalinity levels Example of uses: pH Monitors the acidity or alkalinity levels in the soil in a greenhouse Pollution monitoring in rivers Monitors acidity levels in a chemical process Purpose: Detects presence of a gas in the surroundings Measures the amount of a gas in the surroundings Example of uses: Gas (e.g. O2 or Monitors pollution levels in a river or in the air CO2) Monitors O2 and CO2 levels in a greenhouse Checks for CO2 leaks in a power station Monitors oxygen levels in a car exhaust 57 Ch.4: Automated Systems Eng. Omar El Safty Purpose: Measures the changes in magnetic fields Example of uses: Magnetic field Counting vehicles that cross a bridge Monitoring vehicles that enter a car park Used in anti-lock braking systems (ABS) in motor vehicles Purpose: Measures noise/sound levels in the surroundings Acoustic/Sound Example of uses: Picks up noise levels (e.g. footsteps) in a burglar alarm system Detects the sound of liquids dripping at a faulty pipe joint Purpose: Measures changes in velocity (speed and direction) which includes vibrations, acceleration and deceleration Accelerometer Example of uses: Used in cars to measure rapid deceleration and apply air bags in a crash In mobile phones to detect change between landscape and portrait mode Purpose: Detects the presence of a nearby object Proximity Example of uses: Detects when a face is close to a mobile phone screen Purpose: Measures the amount of liquid/gas flowing through an environment Example of uses: Flow Monitors gas flow in pipes Monitors flow in respiratory devices and inhalers in hospitals 58 Ch.4: Automated Systems Eng. Omar El Safty Purpose: Measures the level of a liquid in a certain space Level Example of uses: Measures the level of a petrol tank in a car Detects leaks in air conditioning 2. Automated Systems Definition: A combination of software and hardware designed and programmed to work automatically without the need for any human intervention. An automated system consists of: Sensors to take readings Microprocessor to process data Actuators to do mechanical output // Output devices to display data Definition of Microprocessor: A type of integrated circuit contained on a single chip. General advantages of using automated systems: Take more accurate readings than humans Higher productivity than humans Can work 24/7 Produce more consistent results than humans Less expensive in the long run than employing humans Work continuously with no breaks.. -.. so any necessary action is initiated immediately Increases safety.. -.. as employees do not need to do dangerous tasks Can increase jobs/skills.. -.. as employees are needed to learn/maintain the equipment No need for workers to do repetitive tasks.. -.. so they can use their time on more skilled tasks 59 Ch.4: Automated Systems Eng. Omar El Safty General disadvantages of using automated systems: A faulty sensor can give false results Subject to cyber attacks Expensive to set up/install Needs more maintenance than traditional systems, which is expensive May lead to deskilling of the workforce 2.1 Domestic applications Regulating the temperature in an air conditioning system Steps: 1 Temperature sensor continually sends digitized value/reading to the microprocessor 2 Microprocessor compares temperature data with stored value/pre-set value 3 If the temperature value is greater than or equal to the stored value, the microprocessor sends a signal to an actuator to turn on the cooling unit 4 If the temperature value is less than the stored value, the microprocessor sends a signal to an actuator to turn off the cooling unit 5 The whole process repeats until the user turns off the system Detecting intruders in a security syetem/burglar alarm system Steps: 1 Sensors continually send digitized value/reading to the microprocessor: § The infra-red sensor picks up the movement of an intruder in the building § The acoustic sensor picks up sounds such as footsteps or breaking glass § The pressure sensor picks up the weight of an intruder 2 Microprocessor compares data from sensors with stored values 3 If data is inside the acceptable range, then no action will be taken 60 Ch.4: Automated Systems Eng. Omar El Safty 4 If any of the incoming data values are outside the acceptable range, then the microprocessor sends a signal to actuator to : § A siren to sound the alarm § A light to start flashing 5 The alarm continues to sound, and lights continue to flash until the system is reset with a password 2.2 Transport Adaptive cruise control Steps: 1 Proximity sensor on the car continually sends digitized value/reading to the microprocessor 2 Microprocessor calculates the distance to the car in front 3 Microprocessor compares the calculated distance to a stored value (safe distance) 4 If distance between vehicles is less than the safe distance, a signal is sent by the microprocessor to actuator to: - Apply brakes - Reduce throttle 5 If the distance between vehicles is greater than the safe distance, the microprocessor will send a signal to the actuator to: - Release brakes - Increase throttle 6 The whole process repeats until the driver switches off the adaptive cruise control system 61 Ch.4: Automated Systems Eng. Omar El Safty 2.3 Industrial applications Control of a nuclear power station Steps: 1 Sensors continually send digitized values/readings (temperature, pressure, flow, level, etc.) to the microprocessor 2 Microprocessor compares data from sensors with stored values 3 If values are inside the accepted range, no action will be taken by the microprocessor 4 If any value is outside the accepted range, a signal is sent by the microprocessor.. 5..to actuators to open/close water pumps, valves, gas pumps, etc. 6 The whole process repeats until the system is turned off 2.4 Science Monitoring chemical processes in a laboratory Steps: 1 Sensors continually send digitized values/readings to the microprocessor - Temperature sensor to measure the temperature - Pressure sensor to measure the pressure - pH sensor to measure the pH - Level sensor to measure the level of the liquids in the experiment - Flow sensor to measure the flow of the gas and liquid in the experiment 2 Microprocessor compares data from the sensors with stored value/pre-set value 3 If the sensor data is greater than or equal to the stored value, the microprocessor sends a signal to the screen to display a warning message and to a buzzer to sound an alarm 4 If the sensor data is less than the stored value, no action will be taken 5 The whole process repeats until the monitoring process stops 62 Ch.4: Automated Systems Eng. Omar El Safty 2.5 Gaming applications Gaming console controllers Sensors used: Accelerometer - Measures and responds to tilting the gaming device forward/backward and side to side Proximity sensor - In-touch pads that can detect finger position, thus increasing user awareness Main advantage of automated systems in gaming: Allow increased human interaction with the game. 2.6 Retail Automatic stock control Steps: Product ID scanned from barcode reader Product ID is searched in the stock database If the product is found, it decrements the product stock by 1/quantity sold If the product is not found, an error message is displayed If stock is below a certain level, the system automatically re-orders stock from the suppliers 63