The following examples discuss a number of devices that can be controlled by a computer:
|
|
#
|
Security lights use infra-red sensors to detect movement. |
|
Security lights with built-in infra-red sensor |
Video of Infra-Red Security Light
|
|
|
#
|
Movement is detected when something (man or beast) breaks the infra-red beam. When this happens, the system will turn on the light.
|
# |
If nothing else breaks the beam after a period of time, the system will turn the light off.
|
|
|
|
|
#
|
Burglar alarms work in almost the same way as a security light system.
|
|
A modern alarm system with infra-red sensors |
|
Input - |
Infra-red sensor detects movement when the sensor is broken and this information is sent to the computer
|
Process - |
Computer makes the decision to sound the alarm
|
Output - |
Alarm is activated. |
|
|
|
|
|
|
Modern central heating systems can be programmed to maintain a constant desirable temperature.
Let's imagine our perfect room temperature was set at 25°C - we could use sensors and a computer to:
- Maintain the optimum temperature of 25°C
- Turn heating off when it rises above 25°C
- Turn heating on when it falls below 25°C
|
|
Programmable heating system |
|
# |
Here is how it would work:
|
|
Input - |
Heat sensor detects the current temperature and sends this data to the computer built into the heating system
|
Process - |
Computer would check the sensor heat data against the temperature setting stored in it's memory. Computer decides if the heating needs to be turned on (or off)
|
Output - |
Heating is switched on or off. |
|
|
|
|
|
Computer Controlled Greenhouse |
|
#
#
|
Automatic greenhouses can provide the optimum conditions for growing plants by using computer control.
Computers can be used to monitor conditions and control a range of applications (devices) to keep the perfect conditions constant.
|
|
Computer controlled greenhouses automatically
detect humidity levels and switch sprinklers on when
the soil becomes too dry
|
|
|
Sensors needed to collect data:
|
- Light sensor
- Moisture sensor
- Heat sensor
|
|
Control applications (devices) needed:
|
|
-
Grow lights to make plants flourish
-
Motor to turn sprinkler on if plants need water
- Heater to warm the greenhouse
-
Motor to open window vent to cool greenhouse down if it gets too hot.
|
|
Click Image to zoom |
How the system works: |
1 |
Computer reads data from sensors and compares it to preset values. |
2 |
If it is too hot = heater turned off and vent opened. |
3 |
If it is too cold = heater switched on and vent is closed. |
4 |
If there is enough light = grow light switched off. |
5 |
If it is too dark = grow light switched on. |
6 |
Wet soil = sprinkler switched off. |
7 |
Dry soil = sprinkler switched on. |
NOTE!
The process will repeat constantly. Sensors continually feed new data into the system and the computer will make decisions based on that data.
|
|
|
|
|
|
|
|
#
|
Other examples of devices that can be controlled by a computer include:
- Automatic Cookers
- Automatic Washing Machines
- Microwaves Ovens.
|
|
|
|
|
|