Monitoring, Measuring and Control

Monitoring, Measuring and Control

1. Monitoring-The process of being aware of what is happening around you

   • Data acquisition- The collection of data from real life situations and conversion into a form that can be used by a computer.

2. Control- When ICT can be used to control other ICT systems or external devices by using data from sensors or instructions or commands written by the user

   • Control system applications examples:
     • Central heating system
       • Burglar Alarms and security systems
         • Electronic Toys and Games
       • Automatic doors
         • Traffic Control Systems
           • Robotics
     • Smart Meters
       • Car Parking Systems

3. Advantages of data logging

   • System doesn't forget to take the reading
     • Time intervals are accurate
   • No human intervention required, it's automatic
     • Safer than manual logging
       • Readings can be taken 24/7 without breaks
         • Can be in situated places e.g. underwater
     • Data is already entered for analysis
     • No human error when taking readings
     • Readings are always taken at exactly the right time
       • Safer than manual logging

4. Disadvantages of data logging

   • Equipment malfunction can cause incorrect readings
   • Equipment is expensive

5. ADC An analogue to digital converter changes analogue signals into digital signals.

   • E.g. When you plug a microphone into a computer, you are plugging it into an ADC which converts the analogue signals from the microphone into digital data that the computer can then process.

6. DAC A digital to analogue converter changes analogue signals into digital signals.

   • E.g. when you plug a loudspeaker into a computer, you are plugging it into a DAC which takes digital data from the computer and coverts it into analogue signals which the loudspeaker converts into sound.

7. Data logger- A hardware device that collects or acquires data and stores it ready for sending to a computer system.

8. Output devices

   • Actuator- The motor and related linkage that is uses in a control system. E.g. used to lift a car park barrier or open a lift door.
   • Lights- Lights can be the output from a control system: they can used in traffic lights or as warning lights on a control panel.
   • Buzzers- Buzzers are used to give an audible output such as alarms or warning, for example in an intensive care unit in a hospital.
   • Robotic Arm- A computer- controlled device that can be moved to a certain location using position sensors as part of a feedback loop.

9. A sensor is a device designed to measure some physical quantity in its Changed data to electrical signals.

   • Send signals to an interface box which is linked to a computer. The interface box converts analogue signals to digital signals that the computer can understand. The computer controlling the process will take readings at regular intervals. The readings are stored in a table and can be displayed in graphs or passed to another application.
     • Examples:
       • Light sensor
         • Infrared sensor
           • Motion/Movement sensor
             • Sound sensor
           • Anemometer (Wind speed)
             • Acid sensor
         • Geiger counter radioactivity)
           • Water sensor
         • Thermistor
         • Pressure sensor

10. Feedback- where the system output is fed back to modify the input

    • Control feedback loop

11. Procedures

    • RIGHT n - Turn right n degrees (RT)
      • LEFT n- Turn left n degrees (LT)
        • BACKWARD n- move back by n squares (BK)
          • FORWARD n- Move forward by n squares (FD)
          • REPEAT n- Repeat the instructions in square brackets n times (REPEAT)

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