Automated systems

Last time

Before we start: last time, in Keeping data safe, you learned these points. Here they are again on one card. Keep them in mind, because today builds on them.

Doors that open themselves

You walk towards a shop door, and it opens. Nobody pressed anything. A sensor noticed you. A microprocessor decided what to do. And a motor opened the door. That is an automated system.

What is an automated system?

An automated system is a combination of hardware and software. It carries out a task without human intervention. It uses sensors, a microprocessor and actuators.

The three parts

A sensor measures a physical property, such as temperature, light or distance. An analogue to digital converter changes analogue readings to digital. The microprocessor compares the readings with stored values, and decides what to do. An actuator, such as a motor, a heater or a valve, carries out the action.

A loop that never stops

The sensor measures. The microprocessor compares the reading with the stored value. If action is needed, a signal goes to the actuator. And then the cycle repeats, because the actuator changes the surroundings and the sensor measures again.

How it works, step by step

One: the sensors continuously measure, and send the data to the microprocessor. Two: the microprocessor compares the data with stored values. Three: if the reading is outside the range, it signals the actuator. Four: the process repeats, until the system is switched off.

A greenhouse

The stored range is eighteen to twenty-five degrees. Sixteen is below eighteen, so the heater goes on. Nineteen is inside the range, so there is no action. Twenty-seven is above twenty-five, so a window is opened. Exactly twenty-four, twenty-five, are inside the range.