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# Electric Vehicle (electronics/components) question. What would be the best tool for the job? Answered

I am starting an electric vehicle project. For this project I have two motors, each powering to 2 fixed wheels. I will have a computer (Arduino-ish) supply power to these motors based on the graph of cos 2x (1 being 100% power ratio). The the steering wheel is the input of the degrees/radians.

(Now comes my question)

I will need some way for the computer to know what degree the steering wheel is currently at, (0 degrees= strait,  -90 degrees=90 degrees left, 90 degrees of course being 90 degrees right.) what would be the most efficient way of doing this?

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## Discussions

A potentiometer coupled to the shaft of the steering wheel is another option. This would allow for an absolute determination of the angle.

Your microprocessor or computer would need to include an A/D converter, which is very common. The angle of travel of many potentiometers is about 270 degrees, so it would include the +/- 90 travel of your application.

Potentiometers with a 1/4" diamter shaft are common and inexpensive, and are fairly easy to couple mechanically to the steering wheel shaft.

I'd image just using a couple of gears to couple it to the steering wheel shaft.
That's the best way I can think of.

Then loose the steering wheel and track your forehead.
Left right for direction, up down for speed.

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This sounds dangerous, just in my opinion. When you are steering from the back it whips the front all over the place. We have a mower that runs like this and it is just scary because it goes way to fast. Unless you are dropping the power on one side to compensate for you actually turning the wheels. I know I am not being any help, but I am very sure that iceng has your problem solved

How to steer thee, "let me count the ways" Elizabeth Barrett Browning
1)  Tooth wheel and a inductive pick up. (low cost busy uP)
2)  Optical wheel see image. (low & medium cost busy uP)
3)  Rotary encoder [ gears/belt ] (High price can give absolute position)
4)  Multi turn pot [ gears/belt ] (low cost absolute position)

Adafruit makes a really neat  rotary sensor see image for under \$20 Wow.
( see the yellow ring pic )

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Sorry, not adafruit  but sparksfun electronics who makes that neat \$19
rotary sensor.
It has a resistive response that should have the resolution you need for
your steering.  Just use the ADC input of the processor of your choice.
A 10 bit ADC is better then an 8,   Right... anyone knows that...

One other thing, this sensor has is inherent good repeatability, very useful
if you want the straight ahead position of your steering wheel to be the
same after every turn.
Gears and belts can slip and skip while a good wiper can be pinned.

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