Re: [mowbot] Experiment in speed

Dave Everett (deverett nospam at
Thu, 03 Jun 1999 18:19:43 +1000

At 21:02 02-06-99 -0400, Michael Davenport wrote:
>An experiment in determining speed for my RC lawn mower:
>So, it looks like I'll have to use 12" wheels in order to use direct drive
>from window winder motors (I'm planning to use one at each corner) - The
>ones I have seen are usually rated in the neighborhood of 100 RPM, so I'll
>have to drive them from full stop to full RPM. Can this be done with PWM
>signals? I should be able to get 118 from a 100 RPM motor by increasing the
>voltage slightly, right?
Michael, bear in mind that under load the motors will run at less than
100RPM, maybe 70RPM depending on terrain and slope. You will get more speed
with more volts, but you will generate more heat in the windings and get
less torque.

You can control from 0 to 100% but it might be just as useful to have
perhaps 3-5 speeds between 0 and 100% instead of trying to get the full range.

Dave Everett

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