Newsgroups: comp.robotics
Path: brunix!news.Brown.EDU!qt.cs.utexas.edu!yale.edu!newsserver.jvnc.net!darwin.sura.net!zaphod.mps.ohio-state.edu!uwm.edu!src.honeywell.com!The-Star.honeywell.com!umn.edu!mmm.serc.3m.com!mmc.mmmg.com!timbuk.cray.com!hemlock.cray.com!kilian
From: kilian@cray.com (Alan Kilian)
Subject: Re: RPM -> Speed
Message-ID: <1993Feb15.130202.26589@hemlock.cray.com>
Lines: 36
Nntp-Posting-Host: gopher
Organization: Cray Research, Inc.
Date: 15 Feb 93 13:02:02 CST

Well I'm not sure it will help, but here are the equations you need
to figure out the speed of your robot knowing the RPM and wheel size.

Speed = 3 * Diameter of wheel * RPM

For example:
  You have a 5.5 Inch diameter wheel and it is going 10 RPM.
  Speed = 3 * 5.5 * 10
  Speed = 165            Inches per minute
  Speed = 14             Feet per minute    (Divide by twelve)
  Speed = 1/4            Feet per second    (Divide by sixty)

O.K. What if you know the wheel diameter and the desired speed and you
want to know how fast a motor to get:

RPM = Speed / (3 * Diameter of wheel)

For example:
  You have a 5.5 Inch diameter wheel and you want your robot to go 170
  Inches per minute
  RPM = 170 / (3 * 5.5)
  RPM = 10                    (Interesting that we got 10 huh?)

You can use any units you like for speed and diameter just make sure you
convert to the same units before you plug them in and realise that the result
depends on the input units.

By the way, What do you do at ATT?
Is ATT interested in robots or is this just a hobby?

                    -Alan Kilian

-- 
 -Alan Kilian           kilian@cray.com 612.683.5499 (Work) 612.721.3990 (Home)
 "It is a little hard to tell the difference between a machine that doesn't
  work and a machine that doesn't exist." -Martin Walker quoting someone else
