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From: ear@usfirst.usfirst.org (Eric A. Rasmussen)
Subject: Re: Getting a robot into motion
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Date: Thu, 13 Jul 1995 16:41:41 GMT
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In article <DBnKrt.DMq@switch.com>, Tom Maier  <tam@rnd.switch.com> wrote:
>OK, I *should* know how to figure this out but college physics was
>just too long ago.
>
>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?

You do not have sufficient information to determine necessary motor power.
Power is velocity multiplied by force.  Torque is rotational force.  Torque
is needed to accelerate the robot as well as keep it moving in the presence
of friction and opposing forces.  You need a minumum torque to overcome
static friction to start moving.  You need a certain torque to achieve a
certain acceleration based on mass.  You need a certain torque to overcome
rolling (dynamic) resistance, climb hills, etc.  You need a certain power to
maintain a certain torque at a certain velocity.  You also need to consider
the efficiency of any drive train, when calculating your requirements.

Or you could just get a big motor and see how it works.

--------------------< Eric Rasmussen - ear@usfirst.mv.com >---------------------
U.S. FIRST=U.S. Foundation for Inspiration & Recognition of Science & Technology
