Subject:
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Re: speed control help
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Wed, 23 Jun 1999 16:05:00 GMT
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Original-From:
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Will <nepenthe@montana.&antispam&com>
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Viewed:
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740 times
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lroska wrote:
<snip>
> My robot is curently configured for differential steering and have
> shaft encoders installed on each one for feedback. • <snip>
> The problem is that the motors are non linear in respect to the power
> applied to them. • <snip>
> the speed control software i'm using is assuming that the response is
> linear so for 50% power it expects to see 32 pulses/s but in fact it is
> receiving 50 pulses/s therefore it slows down the motor to a crawl.
<snip>
The easy solution is to avoid using a formula that assumes anything about the motor speed curve (except of course that reducing the motor value reduces the speed).
Try using a feedback mechanism: Keep track of the cumulative pulses from each wheel; while the difference between the two is non-zero, keep decrementing (or incrementing) one of the motor values. This will rapidly fine tune itself to the particular characteristics of the motors, batteries, terrain, etc. You can have a sort of speed control daemon running in a separate process. Works for me! Good luck.
-- Will
P.S.--The *smooth* PWM routine (available from the HB web site) is probably needed for this application.
, ,
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~~~~~~~~~ ' ` ~~~~~~~~~~~ ` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Wendy Parson, America's one of the finest countries
Will Bain, anyone ever stole.
& Tatoosh --Bobcat Goldthwait
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Message is in Reply To:
 | | speed control help
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| I have a problem that involves speed control. My robot is curently configured for differential steering and have shaft encoders installed on each one for feedback. the shaft encoders generate 64 pulses /rev The motors are PWM using the rug warrior (...) (25 years ago, 23-Jun-99, to lugnet.robotics.handyboard)
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