Newsgroups: comp.robotics
Path: brunix!uunet!timbuk.cray.com!hemlock.cray.com!kilian
From: kilian@cray.com (Alan Kilian)
Subject: PWM frequency question
Message-ID: <1992Mar11.093429.13489@hemlock.cray.com>
Date: 11 Mar 92 09:34:29 CST

I am just starting to use Pulse-Width-Modulation to control the speed
of a small 10Volt DC motor in a robot.

I didn't know what frequency to use so I started at 256 Hz. The motor
didn't have much power at 75% On time. so I increased it to 4000 Hz.
The motor made a whine but didn't have any more power. Then I reduced it to
16Hz and the motor worked O.K but had a funny vibration (Like 16Hz maybe huh?)
So I increased it to 16000Hz and everything works much better. The motor has
good torque at a good range of speeds and doesn't vibrate or make any noise
more than the normal motor noise.

So here's the question: Is 16000 Hz a good frequency ti use? I know it works
but I'd like to use as little battery power as possible of course so if
4000 or 32000 Hz is better I'd just use that.

The motors draw about .15 Amps with the load of the robot platform at 75%

                         Thanks,
                           -Alan Kilian



-- 
 -Alan Kilian         kilian@cray.com 612.683.5499 (Work) 612.729.1652 (Home)
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