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IGCSE ICT True control system is when the computer is controlling the output dependent on information from sensors about what is happening. Be able to.

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Presentation on theme: "IGCSE ICT True control system is when the computer is controlling the output dependent on information from sensors about what is happening. Be able to."— Presentation transcript:

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2 IGCSE ICT

3 True control system is when the computer is controlling the output dependent on information from sensors about what is happening. Be able to describe a number of uses, giving the hardware and software requirements. Be able to describe the applications that these uses can be put to. Computers can control systems far more accurately, and respond to changes far more quickly than a human could

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5 Uses microprocessors or computers to control certain physical conditions Sensors take measurements, then A/D converter converts them into digital signals The measurements are compared to stored (predefined) values Processor makes a decision based on the comparison Control output devices will be used

6 Turtle Graphics (LOGO) Control of Lights and Lamps Traffic Control System Control of Washing Machines Robotics Burglar Alarms Central Heating Video Recorders Microwave Ovens Control of Automatic Cookers Central Air Conditioning Computer-controlled Greenhouses

7 Physical conditions (variables) that are controlled by computer/microprocessors include: Temperature Pressure Humidity Light Moisture etc

8 Numeric Keypad Push buttons/switches Temperature sensor Moisture sensor Pressure sensor Light sensor

9 ADC (A/D Converter) DAC (D/A Converter) Timer Algorithms to compare data from sensors to predefined values or ranges Signals sent to control output devices

10 Robot Fans Heaters Boilers Buzzer/alarm Lights LED display Motors

11 A light sensor to detect how much light the plants are getting A temperature sensor to see how cold/hot the greenhouse is A moisture sensor to se how wet/dry the soil is Lights to illuminate the plants if it gets too dark A heater to warm up the greenhouse if it gets too cold A water pump for the watering system A motor to open the window if it gets too warm inside ADC

12 InputsProcessesOutputs Light SensorSensors monitor amount of light, moisture, temperature continuously Light Moisture Sensor Analogue data from sensors converted to digital using ADC Water Pump Temperature sensorTemperature compared to preset range/value Heater Signal sent to turn on heater and use motor to close window if too cold Motor Signal sent to turn off heater and use motor to open windows if too warm Signal to actuator to turn water pump on if soil dry or off is soil is moist

13 Sensors are needed to monitor temperature (continuously) Microprocessor compares the temperature with a preset value/range Depending on result microprocessor causes the fan motor to speed up or slow down Fan motor switched on or off

14 InputsProcessesOutputs Buttons/touchscreenSensors monitor temperature continuously LED display Contact switchAnalogue data from sensors converted to digital using ADC Fan Temperature sensorTemperature compared to preset range/value Buzzer Pressure sensorSignal sent to actuator to switch fan on or off

15 Output directly affects the input No human intervention is necessary Good for situations where control is required 24/7, or in a dangerous/difficult environment

16 Sensors continuously monitor temperature Microprocessor compares the temperature with a preset value/range Depending on result microprocessor causes the fan motor to speed up or slow down Fan motor switched on or off

17 InputsProcessesOutputs Contact switch (door)Sensors monitor temperature continuously LED display Pressure sensor (door)Analogue data from temperature sensor converted to digital by ADC Compressor Number pad or dialTemperature compared to preset range/value input by user Buzzer Temperature sensorSignal sent to actuator to switch compressor on if temp is too high Signal sent to actuator to switch compressor off if temp is OK

18 Sensors are needed to monitor temperature (continuously) Microprocessor compares the temperature with a preset value/range Microprocessor controls two actuators one opens gas valves in the boiler the other switches the pump on

19 InputsProcessesOutputs Touch screenSensors monitor temperature continuously LED display Number pad or dial Analogue data from temperature sensor converted to digital by ADC Radiators Temperature sensor Temperature compared to preset range/value input by user Signal sent to actuators to switch pump on & open valves if temp is too low Signal sent to actuator to switch pump off/close valves if temp is OK

20 2 User inputs: Desired temperature Length of cooking time Sensor measures the temperature in the cooker Microprocessor controls a heating element to keep the temperature constant Microprocessor controls a buzzer to inform the user when the time is up.

21 InputsProcessesOutputs Touch screen/Keypad Sensors activated Temperature Sensor Checks if temperature greater than the temperature from the sensor Buzzer TimerHeater Analogue data from sensors converted to digital by ADC

22 User inputs a code to set the alarm when they leave the house and a code to stop the alarm being triggered when they re-enter the house Detects when a door or window is open using a simple magnet and contact switch If the movement sensor senses something, the computer can immediately decide what to do

23 InputsProcessesOutputs Touch screen/KeypadSensors activated Light Sensor Checks if lights have been turned onBuzzer/Alarm activated Movement Sensor (senses infra-red light changes) Detects if something is moving within a certain range Magnet/Contact Switch Checks if doors/windows are open Analogue data from sensors converted to digital by ADC

24 Control software


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