Newsgroups: comp.robotics
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From: "J.C.Beeksma" <jbeeksma@kranendonk.nl>
Subject: Re: Getting a robot into motion
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Date: Thu, 13 Jul 1995 18:45:44 GMT
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Tom Maier <tam@rnd.switch.com> wrote:

>Given that a robot weighs, say 25 pounds, uses 4 inch tires, and has
>a desired top speed of 1 mph (~1.5ft/sec), how big much power (torque ?) 
>does the motor have to produce to accomplish this?
>
>I'm not looking for the answer per se, I want to understand how to calculate 
>it and what effects/information one has to know before the calculation
>can be made.

Hi,

You're only at the start of the problem. What makes the robot need power to even move on a 
horizontal surface is the friction. If there was none, it would only need power to accelerate 
or to go uphill, not to keep an even speed. Using ball bearing can help you. Also, soft tires 
will consume energy (being deformed, and turning 'mechanical' energy into heat... such a 
waste!

I dont have all the required formulae present, but if you're still interested, i can try to 
set up a physical 'model' to help you.. just drop me a mail to say yes.

We (Kranendonk) deal with industrial robots all the time. If we have to move them, it is 
allways on steel wheels, on steel rails as well for friction reasond described above. Minf 
you, we are talking robots between 350 and 850 kg here, sometimes with tonnes of steel!

Hope to have set *you* on a track ;-),


-- 
Jacob Beeksma <jbeeksma@kranendonk.nl>

Postbus 6147, NL-4000 Tiel, The Netherlands
Phone: +31 3440 23944   Fax: +31 3440 23388


