Automated Systems
Automated and Emerging Technologies
An automated system that just keeps running forever is only useful if it can respond to changes in the environment. The key idea that makes this possible is the .
A feedback loop is the cycle by which the output of a system is fed back as an input, so that the system can compare its current state with the target state and adjust accordingly.
In an automated control system, the loop usually looks like this:
- The sensor measures the current state of the environment.
- The microprocessor compares the reading to the target.
- The microprocessor adjusts the actuator to push the environment back towards the target.
- The actuator's action changes the environment.
- The sensor takes a fresh reading, and the cycle repeats.
The output of the actuator changes the very thing that the sensor is measuring; that change feeds back into the next reading. This makes the system self-correcting.
Common exam question
Describing the role of the microprocessor in a system
Question: Describe the role of the microprocessor in this system and how it checks or updates something, such as whether a parking ticket is paid or the stock when a book is borrowed (3–4 marks).
Asked in 3 of the 17 papers, at one mark per point. Write the same three steps each time: the microprocessor receives the data (from a sensor, a reader or a checkout), it compares the data with stored data (a set range, or a database record), and it sends a signal to trigger the action. Add both outcomes: a match raises the barrier or cuts the stock by one; no match leaves the barrier down or shows an error message. One scheme also credits analysing the data, but comparing with stored data is credited by all three.
Two of the three systems had no sensor (a ticket reader, a self-checkout), so say where the data comes from rather than forcing a sensor into the answer.