How Can Computers Measure Things?
A sensor, such as a temperature sensor, can be connected to a computer. The computer can then monitor the signal from the sensor, reacting to changes, or it can record the data from the sensor at predefined time intervals.
Note: If the sensor is an analogue one, then an analogue-to-digital converter (ADC) will be required.
Where is Computer Measurement Used?
Anywhere that data needs to be gathered regularly, a computerised data-logging system can be used. Some examples are shown below…
Many experiments can be set-up and left to run with a data-logging system measuring things like the temperature of a liquid, etc.
Often these are placed in very remote areas to collect data about rainfall, temperature, wind-speed, wind-direction, etc. Data needs to be gathered all day, every day. This data can then be used by weather forecasters to help predict the weather over the coming days.
Scientists are very concerned about the effect that humans are having on the environment. Computer-based data-logging is often used to help gather evidence of these effects: the level of water in a dam, the speed of water flowing down a river, the amount of pollution in the air, etc.
Why Use Computers to Measure Things?
The main reasons that you would want to use a computer-based data-logging system, instead of a person taking measurements are…
- Computers do not need to take breaks – they can log data all day, every day, without stopping
- Computers take much more accurate readings than humans can
- Computers can take data readings more frequently (1000s of times a second if necessary)
- Since the logged data is already in a computer, the data can be analysed more quickly and easily (graphs drawn instantly, etc.)
- Data logging systems can operate in difficult environments (e.g. in the Arctic, or on top of a mountain)
- People are free to do other more useful tasks (rather than watching a thermometer)
Microprocessors in Control Applications
Control applications or systems are like other system as they have three main parts:
- Input provided by sensors
- Process by computers
- Output to actuators
(Actuators (outputs from the computer) are the devices that make things happen on the production line)
Computer controlled applications can be found in:
- turtle graphics,
- automatic washing machines,
- automatic cookers,
- computer controlled central heating systems,
- burglar alarms,
- computer controlled glasshouse