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 16:45:19 GMT
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Original-From:
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Gary Livick <glivick@pacbell.(Spamcake)net>
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Viewed:
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930 times
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It sounds like you are running open loop. If you use the wheel encoders as
feedback devices to close the loop, then you can use the motor control
function in your program as a variable to adjust motor control current via
PWM to match the command speed. It is basically a fly-by-wire system
then. You command a target speed, give it to the motor control logic and
then let the software maintain the command speed. The result should be
that the robot will move at the command speed when going up hill, down
hill, over rough carpet and over smooth surfaces within the torque
limitations of your motors.
The code to do this has already been generated. If you look at the Rug
Warrior book, "Mobile Robots, 2nd ed." on page 393, there it is. The first
edition of the book also describes the method in detail.
Gary Livick
lroska wrote:
> 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 setup.
>
> The problem is that the motors are non linear in respect to the power
> applied to them.
>
> At full power (100%) the shaft encoders return 64 pulses/s
> at 75% they return 62 pulses/s, at 50% power they return 60 pulses/s
> and at 25% they return 50 pulses/s
>
> 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.
>
> Is there a formula that I can use to solve for the expected pulses/s for
> a given power input?
>
> Any help is appreciated!
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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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