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I want to make a ATMega-based module to record several parameters of a go-kart while driving - pedals position, speed of the wheels and g-forces. I have a problem with choosing how to measure gas and brake pedals position. I was thinking about putting a small neodymium magnet on the pedal and magnetometer connected to the module on the floor. Is it a good way to do it? The pedal movement is just few inches. I don't to use resistors and movable parts because I'm worried it might break and block the pedals, which isn't a good thing when driving flat out.

Also, is the an easy way to measure angle of the steering wheel?

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Potentiometers do not tend to "freeze up" when they break. Most likely, they will just stop having sensible values and that's that. If they fail catastrophically, they will disintegrate into small bits, leaving the pedal entirely free. – arne Apr 8 '14 at 14:36

Why not use a throttle position sensor from a car?

They are robust potentiometers designed for the job, available in a variety of mounting styles. Some operate directly on a spindle, some have an arm or other mechanism that lends itself to using a control cable or linkage.

Many modern cars the accelerator pedal itself is just a potentiometer, you could mount one of them under the pedal.

Edit to add: Air suspension height sensors often work the same way and have handy actuating rods, P38 Range Rover I know specifically are suitable.

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Was about to post exactly the same thing, after reading the question. – Joe Apr 8 '14 at 12:04
+1 for hinting towards those suspension sensors! – JimmyB Apr 8 '14 at 14:38

One type of sensor that's particularly easy to retrofit to existing equipment is the string potentiometer. It's basically a small unit with a spring-loaded string or flexible wire coming out one side, and it tells you how far the string has been pulled out. You can measure linear displacement directly, or wrap the string around a shaft to measure rotation.

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