Learning Objectives
By the end of this lesson, you will be able to:
- Describe how sensors, microprocessors and actuators can be used in collaboration to create automated systems
- Describe the advantages and disadvantages of an automated system used for a given scenario
- Identify and describe the different types of sensors and their applications
- Explain the difference between monitoring systems and control systems
- Understand the role of an analogue-to-digital converter (ADC) and a digital-to-analogue converter (DAC)
- Apply knowledge of automated systems to scenarios from industry, transport, agriculture, weather, gaming, lighting and science
Key Terms
- Automated system- a combination of software and hardware (sensors, microprocessors and actuators) that is designed and programmed to work automatically without the need for human intervention.
- Sensor- an input device that takes readings or measurements of physical properties (such as temperature, pressure or light) from its surroundings and sends this data to a microprocessor or computer.
- Microprocessor- a chip that processes data received from sensors and makes decisions based on pre-programmed rules or stored values.
- Actuator- a mechanical or electromechanical device (such as a relay, solenoid or motor) that converts an electrical signal into a physical movement or action.
- Analogue data- data that is constantly changing and does not have a discrete value (e.g. a wave-like signal from a temperature sensor).
- Digital data- data represented as discrete values (0s and 1s) that a computer can process.
- Analogue-to-Digital Converter (ADC)- a device that converts analogue (physical, continuously varying) signals into discrete digital values that a computer can understand.
- Digital-to-Analogue Converter (DAC)- a device that converts digital signals back into analogue form so that devices like motors and valves can be operated.
- Monitoring system- a system that records and reports data from sensors but doesnotmake any changes to the process being monitored.
- Control system- a system that takes action and alters a process based on data received from sensors.
- Feedback loop- when the output (change) from an automated system affects the next set of input values received from sensors, causing the process to repeat continuously.
- Solenoid- a type of actuator that converts an electrical signal into a magnetic field, producing linear motion (a plunger moves inside a coil).
What Are Automated Systems?
Anautomated systemis a combination of software and hardware that is designed and programmed to workautomatically without the need for human intervention. However, such systems often still involve human monitoring.
Automated systems are made usingthree key components:
Sensors
Take measurements from the environment and provide input to the microprocessor
Microprocessors
Process the information and make decisions based on pre-programmed rules
Actuators
Make physical changes based on instructions (outputs) from the microprocessor
The Input-Process-Output Cycle
Every automated system follows this simple three-stage cycle:
Sensor detects data in the environment
Computer analyses data & decides action
Device carries out the instruction
Real-Life Example: Central Heating
- Input:A heat sensor detects the current room temperature and sends this data to the computer
- Process:The computer checks the sensor data against the temperature setting stored in memory (e.g. 25°C). It decides if heating needs to be turned on or off
- Output:The heating is switched on or off (e.g. a gas valve is opened or closed, and a water pump is activated)
Activity 6A: Identifying the IPO Cycle
Difficulty: Easy • Estimated time: 5 minutes
A burglar alarm system uses an infra-red sensor to detect movement. When movement is detected, the system sounds an alarm. Describe theInput,ProcessandOutputstages of this system.
- Input:The infra-red sensor detects movement when the beam is broken. This data is sent to the computer (via an ADC if it is analogue).
- Process:The computer/microprocessor analyses the data and compares it with stored values to decide whether to sound the alarm.
- Output:If the data is outside the acceptable range, a signal is sent to the alarm (actuator) and the alarm is sounded.
Activity 6B: Sensors, Microprocessors and Actuators
Difficulty: Easy • Estimated time: 5 minutes
Match each component to its correct role:Sensor, Microprocessor, Actuator.
- Takes measurements from the environment.
- Makes physical changes such as opening a valve.
- Processes information and makes decisions.
- Sensor- Input devices that read/measure physical properties from their surroundings.
- Actuator- Electromechanical devices that convert signals into movement (e.g. relay, solenoid, motor).
- Microprocessor- Processes data and takes necessary action based on programming.
Check Your Understanding: Automated Systems
1. What is an automated system?
An automated system is a combination of software and hardware (sensors, microprocessors and actuators) that is designed and programmed to work automatically without the need for human intervention. However, such systems often involve human monitoring.
2. Name the three main components of an automated system and state the role of each.
- Sensor:An input device that takes readings/measurements of physical properties from its surroundings and sends this data to a microprocessor.
- Microprocessor:Processes the data received from sensors and makes decisions based on pre-programmed rules or stored values.
- Actuator:A mechanical or electromechanical device that converts an electrical signal into a physical movement or action (e.g. relay, solenoid, motor).
3. Describe the Input-Process-Output cycle in an automated system.
- Input:Sensor detects data in the environment around it.
- Process:Data is passed to a computer (microprocessor) which analyses it and decides what action to take. The computer sends instructions to the device telling it what to do.
- Output:The device carries out the instructions (e.g. turns on a light, sounds an alarm, opens a valve).
4. Give two examples of physical changes that an actuator can make.
- Opening or closing a door or valve.
- Activating an alarm (e.g. a siren).
5. Explain what is meant by "human monitoring" in an automated system.
Although an automated system works without human intervention, a supervisor often monitors the process remotely. For example, in a nuclear power station, a supervisor sits in a remote control room where a schematic of the process is displayed on screen. While the process is fully automatic, the supervisor can still override the system and shut down the process if necessary.
6. Why do automated systems need an ADC between the sensor and the microprocessor?
Sensors measure physical properties inanalogueform (continuously changing values). Computers cannot make sense of analogue data, so anAnalogue-to-Digital Converter (ADC)is needed to convert these physical values into discrete digital values (0s and 1s) that the microprocessor can process.
Advantages of Using Computers to Control Devices
Computers have certain advantages over people when it comes to controlling devices:
Cheaper
If a computer is monitoring and controlling applications, you donot need to employ peopleto do the same job.
Higher Work Rate
Computers can control applicationsall day, every daywithout getting tired or bored.
Safer
Computers can work in conditions that would betoo dangerous for people. Examples include chemical plants, radioactive sites (nuclear power stations) and extremely cold areas (Antarctic).
Accuracy
Computers will respond to inputs from sensorsaccurately every time. For example, a heater will be switched on as soon as the temperature falls below 10°C.
Speed
Computers will respond to data received from sensorsvery quickly. For example, as soon as an infra-red sensor detects an intruder, the alarm will sound.
Real-Life Example: Security Light System
Security lights use infra-red sensors to detect movement. Movement is detected when something (a person or animal) breaks the infra-red beam. When this happens, the system turns on the light. If nothing else breaks the beam after a period of time, the system turns the light off.
- Input:Infra-red sensor detects movement and sends this data to the computer in the security light.
- Process:Computer analyses the data and sends instructions telling the light to turn on.
- Output:Security light reacts to instructions received from the computer and the light switches on.
Activity 6C: Advantages of Computer Control
Difficulty: Easy • Estimated time: 5 minutes
A factory uses robots to spray paint cars. Givetwoadvantages of using computers to control this process rather than human workers, and explain each one.
- Safer:Paint fumes can be harmful to humans. Computers can work in conditions that would be too dangerous for people.
- Higher work rate:Computers can work all day, every day without getting tired or bored, whereas humans need breaks and get fatigued.
- Accuracy:Computers will respond to inputs from sensors accurately every time, ensuring a consistent paint finish.
- Cheaper:In the long run, you do not need to employ as many people.
Check Your Understanding: Advantages of Computer Control
1. Explain why using a computer to control a process can be safer than using people.
Computers can work in conditions that would be too dangerous for people. Examples include chemical plants, radioactive sites (nuclear power stations) and extremely cold areas (Antarctic). This means humans do not have to be exposed to hazardous environments.
2. What is meant by "higher work rate" in the context of computer control?
Computers can control applications all day, every day without getting tired or bored. Unlike humans, they do not need breaks, sleep or holidays, so the process can run continuously.
3. Describe how a security light system works using the Input-Process-Output cycle.
- Input:Infra-red sensor detects movement when the beam is broken and sends data to the computer.
- Process:Computer analyses data and sends instructions telling the light to turn on.
- Output:Security light reacts to instructions and the light switches on.
- If no further movement is detected after a period of time, the system turns the light off.
4. Give one example of a situation where computers can work but humans cannot.
A radioactive site (such as a nuclear power station) or a chemical plant — these are too dangerous for humans due to radiation or toxic chemicals.
Types of Sensors
Asensoris a hardware device that takes measurements of physical properties like temperature, pressure or acidity. Sensors areinput devices— they come in different shapes and sizes, but they all measure physical properties of the environment and translate these measurements into digital information that a computer can use (via an ADC).
Temperature
Measures the temperature of its surroundings or a specific object.
Applications:Central heating, chemical processes, greenhouse control.
Moisture
Measures water levels in soil, based on the electrical resistance of the sample.
Applications:Greenhouse soil monitoring, food processing factories.
Humidity
Measures the amount of water vapour in air, based on conductivity changes.
Applications:Factory microchip production, greenhouse monitoring.
Light
Uses photoelectric cells that produce an output based on the brightness of light.
Applications:Street lights, car headlights, automatic windscreen wipers.
Infrared (Active)
Uses an invisible beam of infrared radiation picked up by a detector. If the beam is broken, the detector senses the change.
Applications:Security alarms, automatic windscreen wipers.
Infrared (Passive)
Measures the heat radiation given off by objects or people.
Applications:Security systems detecting body heat, industrial freezer monitoring.
Pressure
A transducer that generates different electric currents depending on the pressure applied.
Applications:Weighing lorries, gas pressure in a nuclear reactor, tyre pressure.
Acoustic / Sound
Microphones that convert detected sound into electric signals/pulses.
Applications:Security systems detecting intruders, detecting dripping liquids from faulty pipes.
Gas
Most common are oxygen or carbon dioxide sensors; they detect the gas being monitored and produce outputs that vary with gas levels.
Applications:Monitoring pollution at airports, oxygen and CO2levels in a greenhouse, car exhaust monitoring.
pH
Measures acidity through changes in voltages.
Applications:Soil acidity in greenhouses, chemical process control.
Magnetic Field
Measures changes in magnetic fields — signal output depends on how the magnetic field changes.
Applications:Anti-lock braking systems, mobile phones, metal detectors.
Accelerometer
Measures acceleration and motion — the change in velocity (a piezoelectric cell is used).
Applications:Car airbags, mobile phone orientation.
Proximity
Detects the presence of a nearby object.
Applications:Automatic braking systems, smartphone screen detection.
Flow (Rate)
Measures the flow rate of a moving liquid or gas and produces an output based on the amount passing over the sensor.
Applications:Respiratory devices/inhalers, measuring gas flows in pipes.
Level
Uses ultrasonics, capacitance/conductivity, optical or mechanical methods to detect changing liquid levels.
Applications:Petrol tank monitoring, pharmaceutical powder levels, leak detection.
Detailed Sensor Reference Table
| Sensor | Description | Example Applications |
|---|---|---|
| Temperature | Measures temperature of the surroundings by sending signals; these signals change as temperature changes. | Central heating control; monitoring chemical processes; greenhouse temperature control; soil moisture monitoring. |
| Moisture | Measures water levels in soil based on the electrical resistance of the sample being monitored. | Monitoring humidity levels in a building; factory humidity monitoring; greenhouse air moisture. |
| Humidity | Measures the amount of water vapour in air based on the fact that the conductivity of air changes depending on water present. | Switching street lights on/off; car headlights automatically; windscreen wipers. |
| Light | Uses photoelectric cells that produce an output (electric current) depending on the brightness of light. | Car windscreen wipers when rain is detected; security alarm systems. |
| Infrared (Active) | Uses an invisible beam of infrared radiation picked up by a detector; if the beam is broken, the detector senses the change. | Security alarms (detecting body heat); industrial freezer/chiller monitoring. |
| Infrared (Passive) | Measures the heat radiation given off by an object (e.g. an intruder or a fridge). | Weighing lorries at weighing stations; gas pressure in nuclear reactors. |
| Pressure | A transducer that generates different electric currents depending on the pressure applied. | Security system detecting sounds of tools; detecting dripping liquids from faulty pipes. |
| Acoustic / Sound | Microphones that convert detected sound into electric signals/pulses. | Monitoring pollution at airports; greenhouse O2and CO2levels; car exhaust oxygen levels. |
| Gas | Oxygen or carbon dioxide sensors; detect the gas being monitored and produce outputs that vary with gas levels. | Monitoring/controlling soil acidity in greenhouses; chemical process acidity control. |
| pH | Measures acidity through changes in voltages in soil or chemicals. | Detecting magnetic field changes (mobile phones, CD players); anti-lock braking systems. |
| Magnetic Field | Measures changes in magnetic fields — signal output depends on how the magnetic field changes. | Car airbags (rapid deceleration); mobile phones (portrait/landscape). |
| Accelerometer | Measures acceleration and motion — change in velocity (using a piezoelectric cell). | Detecting when a face is close to a phone screen; automatic braking. |
| Proximity | Detects the presence of a nearby object. | Respiratory devices and inhalers; measuring gas flows in pipes. |
| Flow (Rate) | Measures the flow rate of a moving liquid or gas and produces an output based on the amount passing over the sensor. | Petrol tank levels; pharmaceutical powder levels in tablet production; leak detection. |
| Level | Uses ultrasonics, capacitance/conductivity, optical or mechanical methods to detect changing liquid levels. | Tank level monitoring; river water levels; industrial liquid tanks. |
Exam Tip
For the exam, you are required to know about these sensors:Acoustic, Accelerometer, Flow, Gas, Humidity, Infrared, Level, Light, Magnetic field, Moisture, pH, Pressure, Proximity, Temperature.
Activity 6D: Choosing the Right Sensor
Difficulty: Medium • Estimated time: 8 minutes
Choose the most suitable sensor for each situation and explain your choice:
- Detecting an intruder in a dark building.
- Switching on street lights when it gets dark.
- Measuring how much water is in a tank.
- Detecting a gas leak in a laboratory.
- Infrared (passive) sensor— it measures the heat radiation given off by an object or person, which works even in the dark (or acoustic/pressure sensor).
- Light sensor— it uses photoelectric cells that produce an output based on the brightness of light, so it can detect when it gets dark.
- Level sensor— it uses ultrasonics or capacitance/conductivity to detect changing liquid levels in a tank.
- Gas sensor— most common are oxygen or carbon dioxide sensors that detect the gas being monitored and produce outputs that vary with gas levels.
Activity 6E: Sensor Applications
Difficulty: Medium • Estimated time: 8 minutes
For each scenario, name the sensor(s) involved and describe what data they collect:
- A modern car's airbag system.
- A smartphone that rotates the screen when tilted.
- An automatic greenhouse.
- Accelerometer— measures acceleration and motion (change in velocity) to detect rapid deceleration in a crash and deploy airbags.
- Accelerometer— measures acceleration and motion to detect when the phone is held sideways and switch to landscape mode.
- Temperature, Humidity, Light, Moisture, pH sensors— collect data on growing conditions to maintain optimum plant growth.
Check Your Understanding: Sensors
1. What is the difference between an active and a passive infrared sensor?
- Active infrareduses an invisible beam of infrared radiation picked up by a detector. If the beam is broken by an object, the detector senses the change.
- Passive infraredmeasures the heat radiation given off by an object or person — it does not emit its own beam.
2. Which sensor would you use to detect a gas leak in a laboratory and why?
Agas sensor(e.g. carbon monoxide or CO2sensor). It uses various methods to detect levels of a particular gas and produces outputs that vary with the gas levels present. This makes it ideal for detecting leaks.
3. Explain how a light sensor is used in street lighting.
The street light is fitted with a light sensor which constantly sends data to the microprocessor. The data value changes according to whether it is sunny, cloudy, raining or night time. If the sensor reading is below the value stored in memory, a signal is sent to switch the lamp on. If the reading is above or equal to the stored value, the lamp is switched off.
4. Name two sensors that could be used in a greenhouse and state what each measures.
- Temperature sensor— measures heat levels in the greenhouse.
- Moisture sensor— measures water levels in the soil based on electrical resistance.
- Humidity sensor— measures water vapour in the air.
- Light sensor— measures light levels.
- pH sensor— measures acidity/alkalinity of the soil.
5. Why are sensors described as "input devices"?
Sensors are described as input devices because they take readings from their surroundings and send this data to a microprocessor or computer. They provide the input data that the system processes to make decisions.
ADC and DAC — Converting Signals
A sensor is a hardware device that takes measurements of physical properties like temperature, pressure or acidity. The data taken in/measured by a sensor is usually inanalogueform. Computers cannot make sense of these physical quantities, and the data needs to be converted into adigitalformat.
ADC — Analogue to Digital Converter
Converts physical, real-world (analogue) information into discrete digital values that a computer can process.
Analogue data
10011100...
DAC — Digital to Analogue Converter
Used when the computer controls devices (such as a motor or valve). These devices need analogue data to operate, so digital signals must be converted back.
Digital data
Analogue data
Why This Matters
- Without anADC, a computer cannot understand sensor readings (which are analogue).
- Without aDAC, devices like motors and valves would not be able to receive commands from a computer (they need analogue signals).
- The ADC and DAC work together to bridge the gap between the physical world (analogue) and the digital world of computers.
Check Your Understanding: ADC and DAC
1. Why is an ADC needed between a sensor and a microprocessor?
Sensors measure physical properties inanalogueform (continuously changing values). Computers cannot make sense of analogue data, so an ADC is needed to convert these physical values into discrete digital values (0s and 1s) that the microprocessor can process.
2. When is a DAC used in an automated system?
A DAC is used when the computer is controlling devices such as a motor or a valve. These devices needanalogue datato operate, so the digital signals from the computer must be converted back to analogue form.
3. Describe what is meant by "analogue data".
Analogue data is data that is constantly changing and does not have a discrete value. For example, the wave-like signal from a temperature sensor is analogue because it varies continuously.
Monitoring vs Control Systems
Sensors are used in bothmonitoringandcontrolapplications. There is a subtle but important difference between how these two methods work.
Monitoring System
A monitoring systemdoes not make any changesto the process. It simply reports the information/values to the user.
- If new data is outside the acceptable range, a warning message is sent to a screen or an alarm is activated.
- The microprocessor/computer hasno effecton what is being monitored — it is simply "watching" the process.
Control System
A control system cantake control and alterhow a process is working. For example, turning up fans on an air-conditioning machine because the temperature has become too high.
- If new data is outside the acceptable range, the computer sends a signal to a control valve, motor, etc.
- The output from the system affects the next set of inputs from the sensors — this is called afeedback loop.
Monitoring and Control Flowchart
If values are outside range, a warning is sent (e.g. on-screen/alarm).
Microprocessor has no effect on what is being monitored.
If values are outside range, a signal is sent to control a valve/motor.
This change affects the following set of input values — feedback loop.
Monitoring Applications
Monitoring systems do not make any changes to the process; instead they simply report the information/values to the user. For example, a life support system in a hospital will sound an alarm if the patient's heart stops... it will not take action to restart the heart, it only informs doctors that they need to take action.
- Burglar alarm system
- Monitoring a patient's vitals in intensive care
- Checking for intruders in an alarm system
- Monitoring pollution levels
Example: Burglar Alarm Monitoring System
- The system is activated by keying in a password on a keypad.
- 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 coming through a door or through a window.
- The sensor data is passed through an ADC if it is in analogue form to produce digital data.
- The computer/microprocessor samples the digital data at a given frequency (e.g. every five seconds); the data is compared with stored values.
- If any of the incoming data values are outside the acceptable range, the computer sends a signal to a siren to sound the alarm, or a light to start flashing.
- A DAC is used if the devices need analogue values to operate them.
- The alarm continues to sound/lights continue to flash until the system is reset with a password.
Control Applications
Control systems can take control and alter how a process is working. Examples include:
- Air conditioning / heating systems
- Traffic light control
- Automatically turning street lights on and off at night
Example: Control of Street Lighting
- The light sensor sends data to the ADC interface.
- This digitises the data and sends it to the microprocessor.
- The microprocessor samples the data every minute (or at some other frequency rate).
- If the data from the sensor < value stored in memory: a signal is sent from the microprocessor to the street lamp and the lamp is switched on.
- The lamp stays switched on for 30 minutes before the sensor readings are sampled again (this prevents the lamp flickering off and on during brief heavy cloud cover).
- If the data from the sensor >= value stored in memory: a signal is sent and the lamp is switched off.
- The lamp stays switched off for 30 minutes before sensor readings are sampled again.
Examples of Monitoring vs Control
| Examples of Monitoring | Examples of Control |
|---|---|
| Monitoring a patient in a hospital for vital signs (heart rate, temperature) | Turning street lights on at night and off during daylight |
| Checking for intruders in a burglar alarm system | Controlling the temperature in central heating/air conditioning |
| Checking the temperature levels in a car engine | Controlling traffic lights at a road junction |
| Monitoring pollution levels in a river | Operating anti-lock brakes on a car when necessary |
| Controlling the environment in a greenhouse |
Activity 6F: Monitoring or Control?
Difficulty: Easy • Estimated time: 5 minutes
Classify each system as eithermonitoringorcontrol:
- A hospital system that sounds an alarm when a patient's heart rate drops.
- A central heating system that turns the boiler on when the temperature falls below 20°C.
- A system that displays pollution levels on a screen.
- An air conditioning unit that turns on fans when the temperature gets too high.
- Monitoring— it only reports the information (sounds an alarm), it does not make changes to the patient.
- Control— it takes action (turns the boiler on) based on sensor data.
- Monitoring— it only displays/reports the data, no action is taken.
- Control— it takes action (turns fans on) to alter the process.
Check Your Understanding: Monitoring vs Control
1. What is the key difference between a monitoring system and a control system?
- Monitoring system:Does not make any changes to the process — it simply reports the information/values to the user.
- Control system:Can take control and alter how a process is working (e.g. turning up fans, opening valves).
2. Give an example of a monitoring system and explain why it is not a control system.
A life support system in a hospital. It sounds an alarm if the patient's heart stops but does not take action to restart the heart — it only informs doctors that they need to take action. Therefore it monitors but does not control.
3. Explain what is meant by a "feedback loop" in a control system.
A feedback loop occurs when the output from the system affects the next set of input values received from the sensors. This means the process will repeat continuously — sensors continually feed new data into the system and the computer makes decisions based on that data.
4. In the burglar alarm monitoring system, what happens if sensor data is outside the acceptable range?
The computer sends a signal to a siren to sound the alarm, or a light to start flashing. The alarm continues to sound/lights continue to flash until the system is reset with a password.
5. Why does a street light stay on or off for 30 minutes before sensor readings are sampled again?
This prevents the lamp from flickering on and off during brief heavy cloud cover. If the sensor were sampled too frequently, the light might switch on and off repeatedly as clouds pass over.
How Automated Systems Work
Automated systems usually comprisethree distinct components:
Sensors
Take measurements from their environmental surroundings.
Microprocessors
Process the information and make decisions based on predefined rules.
Actuators
Make physical changes based on instructions — e.g. activating an alarm, opening/closing a door or valve.
Feedback Loop
These components are often used to create afeedback loopwhere changes (outputs) from the automated system affect the following set of input values received from the sensors.
Sensors
Microprocessor
Actuators
Output affects next input → process repeats continuously
Smart Braking System Example
- A sensor takes constant readings of the car's distance to objects ahead of it.
- These analogue, real-world values are converted to a format a microprocessor can understand using anADC.
- A microprocessor takes this input and calculates the speed the car is travelling and safe braking distances. If it detects the car is travelling too fast and a collision is likely, it issues commands to brake.
- Digital brake signals are converted into an analogue form — these can then be sent to a motor (actuator), which will apply the brake via aDAC.
- The brake slows the car down.
- The sensor continues to send out values. These will have changed due to the slowing of the car — this is known asfeedback.
Activity 6G: Describing an Automated System
Difficulty: Medium • Estimated time: 8 minutes
A modern car has an automatic braking system. Describe how the sensors, microprocessor and actuators work together in this system.
- A sensor takes constant readings of the car's distance to objects ahead of it.
- These analogue values are converted to digital using an ADC.
- The microprocessor calculates the speed the car is travelling and safe braking distances.
- If the car is travelling too fast and a collision is likely, it issues commands to brake.
- Digital brake signals are converted to analogue using a DAC.
- These signals are sent to a motor (actuator), which applies the brake.
- The brake slows the car down, and the sensor continues to send values (feedback).
Check Your Understanding: How Automated Systems Work
1. Describe the role of each of the three main components of an automated system.
- Sensors:Take measurements from their environmental surroundings and provide these as inputs.
- Microprocessors:Process the information and make decisions based on predefined rules.
- Actuators:Make physical changes based on instructions — e.g. activating an alarm, opening or closing a door or valve.
2. Explain what a feedback loop is and why it is important.
A feedback loop is when the output (change) from the automated system affects the following set of input values received from the sensors. It is important because it allows the system to continuously monitor and adjust itself — the process repeats constantly, with sensors continually feeding new data into the system.
3. In the smart braking system example, what happens at each stage?
- A sensor takes constant readings of the car's distance to objects ahead.
- Analogue values are converted to digital using an ADC.
- The microprocessor calculates speed and safe braking distances; if a collision is likely, it issues commands to brake.
- Digital brake signals are converted to analogue using a DAC.
- The signals are sent to a motor (actuator) which applies the brake.
- The brake slows the car down; sensor values change (feedback).
Advantages and Disadvantages of Automated Systems
Automation is a set of tools, such as software and computer programs, that are designed to perform repetitive tasks. Automation is a process of doing something through the use of machines rather than humans. There are many places that automation can help businesses, such as in manufacturing. However, automation can also save time and money when it comes to marketing by automating individual tasks.
Advantages commonly attributed to automation include higher production rates and increased productivity, more efficient use of materials, better product quality, improved safety, shorter workweeks for labour, and reduced factory lead times. Disadvantages of automation are the cost to replace human labour with automated systems.
General Advantages
- Higher production rates
- Increased productivity
- More efficient use of materials
- Better product quality
- Improved safety
- Shorter workweeks for labour
- Reduced factory lead times
- Long-term cost saving
- Safer — timely interventions
- Safer — keeps humans away from hazardous environments
- Efficient use of materials and resources
- Consistent — results are repeatable
General Disadvantages
- Cost to replace human labour
- Worker displacement
- Needs large capital expenditure
- Can become redundant
- Could introduce new safety hazards
- Short-term expensive to set up
- Significant testing must be done before use
- Open to cyber attacks
- Will only react to programmed scenarios
- Needs to be well maintained
- Unethical — can result in major job losses
Summary Table
| Advantages | Disadvantages |
|---|---|
| Operations can be carried out faster than a human operator. | Initially expensive to set up. |
| Safer because an automated system is more likely to make timely interventions. | Requires significant testing and calibration to ensure it works as intended. |
| Allows humans to keep away from hazardous environments. | Any computerised system is subject to cyber attacks. |
| Processes are more likely to run under optimal conditions for longer. | Requires highly specialised and ongoing maintenance. |
| Long-term cost savings versus a large human workforce. | Only able to respond to specific situations within certain parameters — not as flexible as trained humans able to use intuition and experience. |
| Efficient use of materials and resources leads to increased productivity. | Can result in significant job losses. |
| More consistent and repeatable results. |
Activity 6H: Advantages and Disadvantages Analysis
Difficulty: Medium • Estimated time: 10 minutes
A factory is considering replacing its human workers with robots for assembling electronic devices. Discusstwo advantagesandtwo disadvantagesof this decision.
Advantages:
- Robots can work all day, every day without getting tired or bored, leading to higher production rates.
- Long-term cost savings as fewer human workers need to be employed.
- More consistent and repeatable results, leading to better product quality.
Disadvantages:
- Initially expensive to set up and requires significant testing.
- Can result in significant job losses for human workers.
- Requires highly specialised and ongoing maintenance.
- Systems are subject to cyber attacks.
Check Your Understanding: Advantages & Disadvantages
1. State two advantages of automated systems.
- Operations can be carried out faster than a human operator.
- Safer — keeps humans away from hazardous environments and makes timely interventions.
- Long-term cost savings versus a large human workforce.
- More consistent and repeatable results.
2. State two disadvantages of automated systems.
- Initially expensive to set up.
- Can result in significant job losses.
- Requires highly specialised and ongoing maintenance.
- Subject to cyber attacks.
3. Explain why an automated system might not be as flexible as a human worker.
An automated system is only able to respond to specific situations within certain parameters. It cannot use intuition or experience like a trained human can. If a situation arises that was not programmed or considered during testing, the system may not know how to react.
4. Why might a company hesitate to replace workers with automated systems?
- The initial set-up cost is very high (large capital expenditure).
- Significant testing and calibration must be done before the system can be used.
- It can result in significant job losses, which may be unethical and cause public backlash.
- Ongoing maintenance costs can be expensive.
Automated Systems in Different Scenarios
Automated systems can be used in many different situations and scenarios. They can support partial or full automation using a variety of sensors, microprocessors and actuators/motors.
Industry
Automation in factories uses robotics and is used in hazardous environments such as power plants.
Example: Nuclear Power Station
An automated system is programmed to monitor and control the whole process with no human interaction required. Data from a number of sensors (temperature, pressure, flow level, gas, radiation level) is sent to a Distributed Control System (DCS). If data is analogue, it must first be converted into digital format using an ADC. The DCS has access to a large database containing operational data. If any action needs to be taken, signals are sent to actuators to operate pumps, valves or even an emergency shutdown system.
A supervisor sits in a remote control room where a schematic of the process is displayed on screen. While the process is fully automatic, the supervisor can still override the DCS and shut down the process.
| Advantages | Disadvantages |
|---|---|
| Much faster than a human operator to take necessary action. | Expensive to set up and needs considerable testing. |
| Much safer — keeps humans away from dangerous environments. | Unforeseen conditions could have safety implications. |
| Process runs under optimum conditions. | Any computerised system is subject to cyber attacks. |
| In the long run, it is less expensive as it replaces most of the workforce. | Automated systems always need enhanced maintenance. |
Transport
Self-drive cars, intelligent braking, automatic parking systems, adaptive cruise control.
Intelligent Braking System
- A sensor takes constant readings of a car's distance to objects ahead of it.
- These analogue, real-world values are converted using an ADC.
- A microprocessor calculates the speed the car is travelling and safe braking distances. If it detects the car is travelling too fast and a collision is likely, it issues commands to brake.
- Digital brake signals are converted into an analogue form via a DAC — sent to a motor (actuator) which applies the brake.
- The brake slows the car down.
- The sensor continues to send out values. These will have changed due to the slowing of the car — this is feedback.
Automatic Car Parking System
Driver goes along a row of parked cars. On-board sensors and cameras measure the size of any parking spaces, and the on-board computer warns the driver if a suitable space has been found. The driver then selects auto-parking and the on-board computer takes over. Actuators are used to operate the steering rack, brakes and throttle under full control of the computer. Sensors in the bumpers of the car are both transmitters and receivers. They transmit signals that bounce off objects and are reflected back. The car's on-board computer uses the amount of time it takes for the signal to return to calculate the position of objects.
Adaptive Cruise Control
Adaptive cruise control makes use of sensors, an on-board computer and actuators to allow a car to remain a safe distance from another vehicle. The driver sets a cruising speed on the touch screen. Lasers in the bumpers send out signals constantly, which bounce off the vehicle in front and are reflected back. The time taken for the signal to bounce back is used by the on-board computer to calculate the distance between the two vehicles. If the car is getting too close, the computer sends signals to slow the car down by applying brakes and/or reducing the throttle. If the distance is greater than the safe distance, the computer checks if the current speed equals the value set by the driver and adjusts the throttle accordingly.
| Advantages | Disadvantages |
|---|---|
| Less accidents and traffic congestion. | Transportation drivers lose jobs. |
| Increased logistical efficiency. | Technology reliability issues. |
| Allows same number of cars to use fewer parking spaces. | Over-reliance on automated systems by driver (loss of skills). |
| Safer system since sensors monitor all objects. | Faulty sensors or cameras can send false data. |
| Fewer dents and scratches to cars (reduced insurance claims). | Expensive option that doesn't really save the driver money. |
Agriculture
Commercial greenhouses, automated irrigation systems.
Commercial Greenhouse
Automatic greenhouses can provide the optimum conditions for growing plants by using computer control. Computers monitor conditions and control a range of applications (devices) to keep the perfect conditions constant.
Sensors needed:Temperature, Humidity, Light, Moisture, pH.
Control devices:Grow lights, motor to turn sprinkler on/off, heater, motor to open/close window vent, water valves.
How it works:
- Computer reads data from sensors and compares it to preset values.
- If it is too hot = heater turned off and vent opened.
- If it is too cold = heater switched on and vent closed.
- If there is enough light = grow light switched off.
- If it is too dark = grow light switched on.
- Wet soil = sprinkler switched off.
- Dry soil = sprinkler switched on.
Automated Irrigation System
Watering of crops (irrigation) is fully automatic and involves wireless transmission. This allows the system to be used in very remote areas that are vast in size. Data from an automatic weather station is received by a controller every ten minutes. Ultrasonic water level sensors in crop fields measure the amount of water in irrigation channels. Sensors send their data back via wireless transmitters, picked up by a wireless receiver, which sends data back to the controller. The controller uses this data, together with data from the weather station, to decide whether it is necessary to stop or start a series of water pumps. This is done by sending signals to actuators, which operate the pumps. A supervisor still monitors the process remotely.
| Advantages | Disadvantages |
|---|---|
| Reduced labour costs — system only needs a supervisor to monitor vast areas. | Very high maintenance costs associated with automated systems. |
| Better control of precious resources, such as water. | Expensive to set up initially. |
| Better and more efficient control of the irrigation process. | |
| Faster response than a human having to manually check many irrigation channels. | |
| Safer as temperatures in fields could be 40°C and other risks could exist. |
Weather
Remote weather stations, airport weather stations.
Automated Weather Station
Automated weather stations are designed to save labour and to gather information from remote regions or where constant weather data is a requirement. They require a microprocessor, storage (database), battery (usually with solar-powered charging) and a range of sensors.
Sensors used:
- Thermometer (to measure temperature)
- Anemometer (to measure wind speed)
- Hygrometer (to measure humidity)
- Barometer (to measure air pressure)
- Level sensor (to measure rainfall)
- Light sensor (to measure hours of daylight)
Data from sensors is all sent to a microprocessor. Calculations are then done (e.g. hours of daylight, actual rainfall, wind direction). Data and calculated values are stored on a Central Database. Automated weather stations are sited near airports, where reports are sent out automatically every five minutes to pilots. Part of the weather station that needs actuators is the 'tipping bucket rain gauge' — a signal is sent to an actuator to operate a piston which tips a bucket that was collecting rain water.
| Advantages | Disadvantages |
|---|---|
| Accurate forecasting. | Dependence on accurate sensor data. |
| Improved early warning systems. | Installation and maintenance cost is high. |
| Faster response than a human. | Faulty sensors can send false data leading to malfunction. |
Gaming
Various gaming devices for providing an enhanced user experience.
Responsive Controllers
Gaming devices involve sensors to give a degree of realism to games:
- Accelerometers:Measure acceleration and deceleration — respond to tilting the gaming device forward/backward and side to side.
- Proximity sensors:Used in smart touch pads; electrodes embedded in touch pads detect hand/finger position, increasing user awareness.
Embedded accelerometers and proximity sensors together with a microcontroller in game consoles allow increased human interaction with the game. This allows players to take actions that simulate real events, giving a more immersive gaming experience. Actuators provide haptic feedback, adaptive triggers provide resistance, speakers provide audio feedback, and lighting provides further visual feedback.
| Advantages | Disadvantages |
|---|---|
| Personalised experience. | Reduced creativity & problem solving for players. |
| AI enhanced opponents add challenge. | Repetitive gameplay. |
Lighting
House security lighting, automatic road lighting, smart ambient and atmospheric lighting.
Home Security / Atmospheric Lighting
Microprocessor-controlled lighting uses the following sensors:
- Light sensors:To automatically switch lights on or off depending on ambient lighting.
- Motion sensors:To automatically turn lights on in a room when somebody enters.
- Infrared sensors:Used either as motion detectors or as part of a security system.
As it becomes dark, the light sensor value changes, and the microprocessor sends signals to an interface to control LED lights around the garden. Data from the infrared sensor is used as a security device whenever the house is unoccupied. As it becomes dark, a lighting show in a fountain can also be initiated — a pre-programmed display involving changing colours under microprocessor control. The fountain display itself will be under microprocessor control with signals being sent to actuators to turn water pumps on and off.
| Advantages | Disadvantages |
|---|---|
| Increased energy efficiency. | Lack of human control with light adjustments. |
| Better security with motion-activated systems. | Expensive to set up initially. |
| Possible to control light sources automatically. | Wireless connections can be less reliable than wired systems. |
| Reduced energy consumption since lights are only turned on when necessary. | Automated system requires more maintenance. |
| Possible to program new light displays for various occasions. |
Science
Thousands of applications for automating aspects of scientific research, testing and production.
Chemical Process in a Controlled Laboratory
Imagine an experiment in a pharmaceutical laboratory where two chemicals are reacted together in a vessel. One chemical is being added from a burette which has a tap to control the flow of liquid. The tap is operated automatically using a small actuator to the reaction vessel. Once the reaction is complete, it turns a bright orange colour. The whole process is under microprocessor control. Level sensors measure how much liquid is being added from the burette. This data is sent to the microprocessor. Readings are sent to the microprocessor from a colorimeter next to the vessel, which checks the colour of the chemical produced. The microprocessor controls the opening and closing of the tap by sending signals to an actuator. This means the microprocessor has automatic control of the experiment with no human interaction.
| Advantages | Disadvantages |
|---|---|
| More consistent (repeatable) results. | Less flexible than when using human technicians. |
| Less dangerous especially if chemicals used are hazardous. | Equipment can be expensive to buy and set up. |
| Faster results as several different experiments can be done simultaneously. | High cost development and maintenance. |
| Automatic analysis of results is possible. | Security risks are always present if data is being shared globally. |
| Fewer highly trained staff needed for each experiment. | Potential for algorithm bias. |
| Results/experiments can be monitored anywhere in the world in real time. |
Activity 6I: Scenario Analysis
Difficulty: Hard • Estimated time: 12 minutes
A commercial greenhouse uses an automated system to maintain optimum conditions for plant growth. Describe how the sensors, microprocessor and actuators work together in this system. Include at least three different sensors in your answer.
- Temperature sensor:Measures heat levels. If it is too hot, the microprocessor sends a signal to an actuator to open a window vent and turn the heater off. If too cold, the heater is switched on and the vent is closed.
- Humidity sensor:Measures water vapour in the air. The microprocessor uses this data to maintain optimum humidity for plant growth.
- Light sensor:Measures light levels. If there is enough light, grow lights are switched off. If it is too dark, grow lights are switched on.
- Moisture sensor:Measures water levels in the soil. If the soil is dry, the sprinkler is switched on. If wet, the sprinkler is switched off.
- pH sensor:Measures acidity/alkalinity of the soil to ensure optimal growing conditions.
- The microprocessor reads data from all sensors and compares it to preset values, then sends signals to actuators (motors, valves, switches) to make the necessary changes. This process repeats continuously (feedback loop).
Check Your Understanding: Scenarios
1. Name three sensors used in a nuclear power station and state what each measures.
- Temperature sensor:Measures temperature levels in the reactor.
- Pressure sensor:Measures gas/liquid pressure in the system.
- Flow level sensor:Measures the flow rate of coolant.
- Gas sensor:Detects gas escape.
- Radiation sensor:Detects radiation levels.
2. Describe how an automatic car parking system works.
Driver goes along a row of parked cars. On-board sensors and cameras measure the size of parking spaces, and the on-board computer warns the driver if a suitable space has been found. The driver then selects auto-parking and the on-board computer takes over. Actuators are used to operate the steering rack, brakes and throttle. Sensors in the bumpers transmit signals that bounce off objects and are reflected back. The car's on-board computer uses the time taken for the signal to return to calculate the position of objects, allowing the car to fit into its parking space automatically.
3. What sensors are used in an automated weather station and what does each measure?
- Thermometer:Measures temperature.
- Anemometer:Measures wind speed.
- Hygrometer:Measures humidity.
- Barometer:Measures air pressure.
- Level sensor:Measures rainfall.
- Light sensor:Measures hours of daylight.
4. How do accelerometers and proximity sensors enhance the gaming experience?
- Accelerometers:Measure acceleration/deceleration and respond to tilting the device forward/backward and side to side.
- Proximity sensors:Used in smart touch pads to detect hand/finger position, increasing user awareness.
- Together with a microcontroller, these allow increased human interaction with the game, simulating real events for a more immersive experience.
5. Describe the role of the actuator in the automatic lighting system.
In the automatic lighting system, the actuator controls the water pumps for the fountain display and possibly the lights themselves. The microprocessor sends signals to the actuators to turn water pumps on and off according to the installed program. Actuators are also used to control the LED lights around the garden based on the light sensor readings.
Actuators
When a computer is used to control devices, such as a conveyor belt or a valve, it is usually necessary to use anactuatorto, for example, start/stop the conveyor belt or open/close the valve. An actuator is a mechanical or electromechanical device such as arelay, solenoid or motor.
Example: Solenoid
A solenoid converts an electrical signal into a magnetic field, producing linear motion. If a plunger (for example, a magnetised metal bar) is placed inside a coil, it will move when a current is applied to the coil. This would allow the solenoid to operate a valve or a switch, for example. There are also examples of rotary solenoids where a cylindrical coil is used — when a current is supplied to the coil, it causes a rotational movement of the plunger.
Water pumps
Water pumps
Water pumps
Water pumps
How a Solenoid Works
- An electrical current is applied to a coil of wire.
- This creates an electromagnetic field around the coil.
- If a magnetised metal bar (plunger) is placed inside the coil, it moves when the current is applied.
- This linear motion can operate a valve or a switch.
- Rotary solenoids use a cylindrical coil to cause rotational movement of the plunger instead.
Activity 6J: Actuators in Action
Difficulty: Easy • Estimated time: 5 minutes
Explain how an actuator is different from a sensor. Give one example of each.
- Sensor:An input device that takes measurements from the environment (e.g. a temperature sensor measures heat levels).
- Actuator:An output device that makes physical changes based on instructions from the microprocessor (e.g. a solenoid that opens/closes a valve).
- Sensors provide input; actuators produce output (physical movement or action).
Check Your Understanding: Actuators
1. What is an actuator?
An actuator is a mechanical or electromechanical device such as a relay, solenoid or motor that converts an electrical signal into a physical movement or action. It makes physical changes based on instructions given by the microprocessor.
2. Describe how a solenoid works.
A solenoid converts an electrical signal into a magnetic field, producing linear motion. If a plunger (a magnetised metal bar) is placed inside a coil, it moves when a current is applied to the coil. This allows the solenoid to operate a valve or a switch. Rotary solenoids use a cylindrical coil to cause rotational movement instead.
3. Give two examples of actuators and state what they might control.
- Relay:Controls high-power circuits with a low-power signal (e.g. switching on a heater).
- Solenoid:Opens or closes a valve (e.g. gas supply valve in central heating).
- Motor:Turns a sprinkler on/off or opens/closes a window vent in a greenhouse.
Worked Example
Theme Park Water Spray Game [8 marks]
A theme park has a game where a player tries to run from the start to the finish without getting wet. The system for the game uses sensors and a microprocessor to spray water at a player as they run past each sensor.
Describe how the sensors and the microprocessor are used in this system. [8]
Marking Scheme
- A motion sensor collects data [1]
- This data is converted to digital using an ADC [1]
- The sensor sends data to the microprocessor [1]
- ... where the data is compared to stored data [1]
- If the value is outside range, water will be sprayed [1]
- A signal is sent to the actuator to spray water [1]
- If the value is within range no action is taken [1]
- This runs in a continuous loop [1]
Activity 6K: Practice Exam Question
Difficulty: Hard • Estimated time: 12 minutes
A hospital uses an automated system to monitor patients' vital signs such as heart rate and temperature. Describe how the sensors and the microprocessor are used in this system. [6]
- Sensors (e.g. heart rate sensor, temperature sensor) collect data from the patient continuously.
- If the data is analogue, an ADC converts it into digital format.
- The sensor sends this digital data to the microprocessor.
- The microprocessor compares the data against stored acceptable values.
- If the data is outside the acceptable range, a warning message is sent to a screen or an alarm is activated.
- This is a monitoring system — the microprocessor has no effect on what is being monitored; it simply alerts medical staff.
Check Your Understanding: Worked Example
1. In the water spray game, what happens when the sensor value is outside the range?
If the value is outside range, water will be sprayed. A signal is sent to the actuator to spray water.
2. Why is an ADC needed in the water spray game system?
The motion sensor collects data in analogue form (continuously changing). The ADC converts this data to digital format so the microprocessor can process it.
3. Describe how the microprocessor makes decisions in an automated system.
The microprocessor compares the data received from sensors against stored values (pre-programmed rules). If the value is outside the acceptable range, the microprocessor sends a signal to an actuator to take action. If the value is within range, no action is taken. This process runs in a continuous loop.
Key Takeaways
- An automated system is a combination of software and hardware (sensors, microprocessors and actuators) that works automatically without human intervention.
- All automated systems follow the Input-Process-Output cycle: sensors detect data, the microprocessor processes it, and actuators carry out the action.
- Computers are cheaper, faster, safer, more accurate and can work longer hours than humans for controlling devices.
- Sensors are input devices that measure physical properties (temperature, light, pressure, etc.) and convert them into digital data using an ADC.
- An ADC converts analogue sensor readings into digital data; a DAC converts digital signals back into analogue form to operate devices like motors and valves.
- Monitoring systems only report data; control systems take action and alter the process.
- All sensors convert information into digital format — typically achieved using an ADC.
- Automated systems often use a feedback loop where outputs affect the next set of sensor inputs, so the process repeats continuously.
- Sensors you must know: Acoustic, Accelerometer, Flow, Gas, Humidity, Infrared, Level, Light, Magnetic field, Moisture, pH, Pressure, Proximity, Temperature.
- Actuators are mechanical or electromechanical devices (relay, solenoid, motor) that convert electrical signals into physical movement.
- Automated systems have advantages (faster, safer, cheaper long-term, consistent) and disadvantages (expensive to set up, job losses, maintenance costs, cyber attacks).
- Real-world applications include industry (nuclear power), transport (self-drive cars), agriculture (greenhouses), weather (weather stations), gaming (controllers), lighting (security lights) and science (chemical processes).
Question Bank
1. Describe how sensors, microprocessors and actuators work together in an automated system. [6 marks]
Marking Scheme
- Sensorstake measurements from their environmental surroundings and provide these as inputs. [1]
- If the data is analogue, anADCconverts it to digital format. [1]
- Themicroprocessorprocesses the information and makes decisions based on pre-programmed rules. [1]
- Data is compared against stored values to determine if action is needed. [1]
- If action is needed, signals are sent toactuators. [1]
- Actuators make physical changes (e.g. activating an alarm, opening/closing a door or valve). [1]
Additional Notes for Slow Learners
- Think of it like a human body: sensors are eyes/ears, microprocessor is the brain, actuators are muscles/hands.
- The brain (microprocessor) compares what you see (sensor data) with what you know (stored values) and decides what to do (actuator).
2. Explain the difference between a monitoring system and a control system, giving an example of each. [6 marks]
Marking Scheme
- Monitoring systemdoes not make changes to the process — it simply reports information/values to the user. [1]
- If data is outside acceptable range, a warning is sent or an alarm is activated. [1]
- The microprocessor has no effect on what is being monitored. [1]
- Control systemtakes control and alters how a process is working. [1]
- If data is outside acceptable range, the computer sends a signal to a control valve/motor. [1]
- Output from the system affects the next set of inputs (feedback loop). [1]
Additional Notes for Slow Learners
- Monitoring:Like a CCTV camera — it watches and records but doesn't do anything.
- Control:Like a thermostat — it watches AND turns the heating on/off to change the situation.
3. Describe how an automated system is used in a commercial greenhouse. [8 marks]
Marking Scheme
- Sensors (temperature, humidity, light, moisture, pH) collect data. [1]
- Data is converted to digital using an ADC if analogue. [1]
- Microprocessor compares sensor data to preset values. [1]
- If too hot = heater turned off and vent opened. [1]
- If too cold = heater switched on and vent closed. [1]
- If enough light = grow light switched off; if too dark = grow light switched on. [1]
- Wet soil = sprinkler off; dry soil = sprinkler on. [1]
- Process repeats continuously (feedback loop). [1]
Additional Notes for Slow Learners
- Think of the greenhouse as a hotel for plants — the computer is like a concierge making sure everything is perfect.
- Too hot? Open a window. Too cold? Turn on the heater. Too dark? Turn on the lights. Too dry? Water the plants.
4. Explain the role of an ADC and a DAC in an automated system. [5 marks]
Marking Scheme
- Sensors measure physical properties inanalogueform. [1]
- Computers cannot make sense of analogue data. [1]
- ADCconverts analogue data into discrete digital values. [1]
- DACis used when the computer controls devices (motors, valves). [1]
- These devices need analogue data, so digital signals are converted back. [1]
Additional Notes for Slow Learners
- ADC= Analogue to Digital = sensor reading becomes computer data.
- DAC= Digital to Analogue = computer command becomes physical action.
- Think of ADC as translating a foreign language into English; DAC translates English back.
5. Discuss the advantages and disadvantages of using automated systems in industry. [6 marks]
Marking Scheme
- Advantage:Much faster than a human operator to take any necessary action. [1]
- Advantage:Much safer — keeps humans away from dangerous environments. [1]
- Advantage:In the long run, less expensive as it replaces most of the workforce. [1]
- Disadvantage:Expensive to set up and needs considerable testing. [1]
- Disadvantage:Unforeseen conditions could have safety implications. [1]
- Disadvantage:Any computerised system is subject to cyber attacks. [1]
Additional Notes for Slow Learners
- Think about a car factory: robots can lift heavy parts (safer), work 24/7 (faster), but cost millions to install (expensive) and might be hacked (cyber attack).
6. Name four sensors used in a modern car and describe what each is used for. [8 marks]
Marking Scheme
- Accelerometer:Measures acceleration/motion — used to detect rapid deceleration and deploy airbags. [2]
- Proximity sensor:Detects presence of nearby objects — used in automatic braking systems. [2]
- Light sensor:Measures light levels — used to turn headlights on automatically. [2]
- Infrared sensor:Detects rain or movement — used for automatic windscreen wipers. [2]
Additional Notes for Slow Learners
- Your family car has many sensors working together — the accelerometer knows if you brake suddenly, the proximity sensor knows if you're too close to the car in front, the light sensor knows when to turn on headlights.
7. Describe how a chemical process in a laboratory can be automated. [6 marks]
Marking Scheme
- Two chemicals are reacted together in a vessel. [1]
- One chemical is added from a burette with a tap controlled by an actuator. [1]
- Level sensors measure how much liquid is added and send data to the microprocessor. [1]
- A colorimeter checks the colour of the chemical produced. [1]
- The microprocessor controls the opening/closing of the tap by sending signals to an actuator. [1]
- Once the reaction is complete (bright orange colour), the process stops. [1]
Additional Notes for Slow Learners
- Think of it like a recipe: the computer adds ingredients (chemicals) drop by drop until the dish (reaction) is perfect, then stops.
8. Explain the advantages and disadvantages of using automated systems in agriculture. [6 marks]
Marking Scheme
- Advantage:Reduced labour costs — system only needs a supervisor to monitor vast areas. [1]
- Advantage:Better control of precious resources, such as water. [1]
- Advantage:Faster response than a human having to manually check many irrigation channels. [1]
- Disadvantage:Very high maintenance costs are associated with automated systems. [1]
- Disadvantage:Expensive to set up initially. [1]
- Disadvantage:Less manual labour (can be seen as both advantage and disadvantage). [1]
Additional Notes for Slow Learners
- Imagine watering thousands of plants across a huge field — a computer can do this automatically, but installing the system costs a lot.
9. Describe how sensors and actuators are used in an automatic lighting system for a house. [6 marks]
Marking Scheme
- Light sensor:Automatically switches lights on/off depending on ambient lighting. [2]
- Motion sensor:Automatically turns lights on in a room when somebody enters. [1]
- Infrared sensor:Used as a motion detector or as part of a security system. [1]
- As it becomes dark, the light sensor value changes and the microprocessor sends signals to control LED lights. [1]
- Actuators turn water pumps on/off for fountain displays and control the lights. [1]
Additional Notes for Slow Learners
- Your garden lights probably have a light sensor — they turn on automatically when it gets dark and off when it's light.
- Some homes have motion sensors in hallways — lights turn on when you walk in and off when you leave.
10. Discuss the advantages and disadvantages of automated systems used for weather monitoring. [5 marks]
Marking Scheme
- Advantage:Faster response than a human. [1]
- Advantage:Accurate forecasting. [1]
- Advantage:Improved early warning systems. [1]
- Disadvantage:Installation and maintenance cost is high. [1]
- Disadvantage:Faulty sensors can send false data leading to malfunction. [1]
Additional Notes for Slow Learners
- Weather stations in remote areas can send data automatically every 5 minutes — no human needs to visit these often-dangerous locations.