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[DPRG] Robot math problems

Subject: [DPRG] Robot math problems
From: David Peterson robologist at yahoo.com
Date: Wed Feb 13 15:42:05 CST 2002

Borenstein etc have a part of a chapter in the "Where Am I" paper at
http://www.eecs.umich.edu/~johannb/pos96rep.pdf . This is a huge 282 page
PDF file, but references differential drive equations that should be easy to
code. I haven't been able to figure out how to do a sine and cosine function
appropriately with a Basic Stamp, or to even keep track of encoder ticks at
the rate some of mine are capable of. Pages 19 and 20 go through the
equations. I was trying to see how these equations might come up with the
solution of the 18" centerline that Ed came up with, but haven't seen that
yet. The equations go in more the order of finding incremental postion and
orientation of the robot based on encoder readings for each wheel, a
conversion from polar coordinates to rectangular essentially. Eds answer
makes sense, just can't see how to get it out of these equations.


----- Original Message -----
>From: "Clay Timmons" <ctimmons at cadence.com>
To: <dprglist at dprg.org>
Sent: Wednesday, February 13, 2002 1:37 PM
Subject: [DPRG] Robot math problems

> Just working out a few robot navigation issues
> and thought I'd share a couple math problems
> I've encountered.  Have fun!  Took me about
> 10 minutes.
> If a 12" wide robot with 3" diameter wheels
> has one wheel going 1/2 the speed of the other
> it will go in a circle.
>    1) What diameter is that circle?
>    2) To make the robot go in a circle with
>       a 9" radius on the inside wheel
>       what speed should the inside wheel
>       go as a percentage of the outside wheel?
> I have solutions and will post answers next week.
> -Clay Timmons-

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