Rod Smallwood rodsmallwood52 at btinternet.com
Wed Dec 2 10:33:13 CST 2015

Hi Guys

Circumference and Diameter are linked by the constant Pi and therefore 
are an entity.
Its a little more complex with a rubber wheel and its indented path.

However as we are using closed loop control
when the measured term equals the target term there you are.

You can get into loop filters and lots of nice math if you want.


On 02/12/2015 16:06, Fred Cisin wrote:
> On Wed, 2 Dec 2015, Paul Koning wrote:
>> Actually, it's the circumference that matters, not the diameter.
> I always thought that there was a relatively stable relationship 
> between those!  :-)
> Circumference tends to be a little over 3 times the diameter (3.0 in 
> some states)    :-)
>> Does the circumference of a rubber roll change significantly when you 
>> press on it?
> If it shifts or squeezes out to the sides, not so much.
> If it compresses, yes.
> Before TPMS, some cars got a crude estimation of low tire pressure by 
> comparing the RPM of a tire (ABS sensors) with its fully inflated 
> brethren.
> (circumference changing with pressure change)

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