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Creating a System

Control

For more detailed instructions, see the Getting Started presentation.

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Giving the orders

When you design a system, it’s really important that you write about it in a way that other people can follow.

Sensors can help to make sure the car is in the right place and the brushes move over the car gently without damaging it.

Imagine you are designing a system to wash cars automatically.

You need to make sure the cars will get clean but won’t get damaged.

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A simple car wash might work like this:

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Watching every move

You would need to draw a flow chart to explain

the order that things need to happen in.

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yesyes

no

nono

yes

Start

Stop

Car in position?

Start button pressed?

Drying time over?

Lower exit barrier

Spray foam

Move water/brush bar over length of car

Raise exit barrier

Dryer on

Move bar back to original position

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A system like this would be tested on a computer model first, with cars of lots of different sizes, to make sure it works with all of them. That’s cheaper than damaging real cars if things didn’t work!

Things can only get better

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When the system was tested for real, each part of the process would need to be watched.

Are the cars clean enough? Perhaps they need more foamAre they dry enough? Do the heaters need to be on for longer?

The system needs to be evaluated to see how well it does its job.

It’s important to write down exactly what is happening – if someone needs to change the system later, they need to know exactly what is happening.

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Summary

What can I remember?

When designing a system it must be well documented to enable others to make changes at a later date.

The order of things in a system can be documented using a flow chart.

A system needs to be tested and reviewed using a computer model first to ensure it works under all conditions. This is cheaper and safer than testing the real thing.

The real system still needs to be tested after the computer model.