Steering angle sensor

I'm looking to make a steering angle sensor for my data acquisition system in my race car. I basically need to translate the movement of the steering wheel into voltage read by the logger unit.

The logger provides a 5v reference signal so I figured I could send that signal through a potentiometer then back to the unit.

most commerical units available ($$$) use a system of pulleys driven off of the movement of the steering shaft itself.

some questions -

what type of pot would be good for this application. I understand audio ones are not linear enough?

Anyone have any idea where I can get different sized pulleys to go on the end of the pot?

any other tips advice or different ways of doing it?

thanks!

Jason

Reply to
Chump
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You could linearise with a microcontroller; if the potentiometer has _repeatable_ non-linearity.

Optical or reluctance encoding off the steering shaft.

You could also do it "indirectly" by measuring the linear translation of the steering rack, with potentiometer, linear encoder using optical, potentiometer, inductive, or capacititative measurement.

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/"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia
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Reply to
Bernd Felsche

For curiousity sake.... how much do these commercial units go for? Why?

How linear is linear enough? What are the design requirements for data accuracy? How often is the data sampled?

There are lots of ways to do this that don't involve pulleys (dark ages?)

Regards, Brad

Reply to
BEVERNON

Another quick question.

Are you interested in the steering wheel angle or the angular displacement of the wheels on the ground? Brad

Reply to
BEVERNON

Wouldn't go that way. Potmeters are just not suitable for neither the job nor the environment.

Other options:

- Magnet on the steering wheel axis and some hall sensors.

- Slit disk mounted / coupled to the steering wheel and 2 optical detectors.

Drive carefully :-)

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Kind regards,
Gerard Bok
Reply to
Gerard Bok

Try this. Print out a strip of paper with alternating black bars on it. It should be long enough to fit around your shaft. You need two sets of bars which are shifted by 90 deg from each other.

You use two optical sensors to detect the bars as they pass under them. You count the transistion to find out where you are with respect to your zero or rest point. You use the phase differences between the two sets of bars to determine direction of rotation.

The only physical things you need to do are to attache the paper strip to the shaft and to affix the sensor securely. There will be no physical interference between your shaft and a complex mechanical system of pulleys, therefore it will be safe.

Oh, and the thickness of the bars will depend upon the resolution you need.

Al

Reply to
Al

or just strap a mouse to it.

Reply to
CWatters

LOL..... don't let the ASPCA find out about that. Brad

Reply to
BEVERNON

"Chump" wrote

If the data logger has an analog input this may be the easiest way.

There are special potentiometers for just this purpose. They are normally

1-turn units (300 degrees or so) and that will set the requirements for the pulley/belt/gearing. A standard 10-turn pot will also work, though they are not made for this application. Search the Newark or Arrow electronics sites.

Most potentiometers are linear. Non linear ones are used for volume controls on radios and such.

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Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer:  Electronics; Informatics; Photonics.
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Reply to
Nicholas O. Lindan

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To get the reliability you need you'll probably have to go to an
environmentally sealed precision pot which can stand to live in an
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Reply to
John Fields

Lots - several thousand dollars to 10's of K ( Formula 1 style )

Small market. Heavy environment.

Reply to
tango4

Look at linear displacement sensors ( LVDT or hall effect). Accuracy down to tenths of a millimeter. 0 - 5volt output. Fitted with ball ends so you can link one to a tie rod or the main steering arm quite easily.

Ian

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Reply to
tango4

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You might want to consider a cable pot.
Reply to
John Fields

LVDTs are much better than 0.1 mm--I've used them below 1 um in short-time measurements.

Cheers,

Phil Hobbs

Reply to
Phil Hobbs

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