Subject:
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Re: Balancing robots
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 22 Jan 2004 14:41:52 GMT
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Viewed:
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941 times
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In lugnet.robotics, PeterBalch <PeterBalch@compuserve.com> wrote:
>
> Steve: From reading your code, it seems that you "recalibrates" the "zero"
> point very so often by assuming that the bot is vertical. So slow changes
> in reflectivity shouldn't matter.
>
> I've only been working with simulations so far. It really helps me
> understand what terms are important in the feedback loop. (The Delphi code
> is available to anyone who wants it.)
When trying to balance, there are really just two questions to ask.
1) Is the current angle/tilt/distance-to-floor changing?
2) Are the wheels turning?
If you answer no to both, you are balanced. It really doesn't matter what the
distance-to-floor is.
One thing most people don't understand about Legway is that it WILL balance on a
hill, because it's not trying to adjust to a single value. It's trying to
adjust so (1) the sensors are not changing and (2) the motors are not being
driven.
This is where there is a difference between motor commands, and connecting a
wheel encoder. When it's on a slope, it sends "stop" commands to the wheels, so
it thinks it's stopped, but in fact gravity is causing it to roll down the hill.
But that's a different subject.
So, to balance, all you need to do is detect if the tilt angle of the robot is
changing. If it is, you need to drive the motors.
If it isn't changing, but you're driving the motors, you need to drive them a
bit more to 'right' yourself.
Also, the more it's changing, the more you need to drive the motors.
Steve
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Message is in Reply To:
 | | Re: Balancing robots
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| Allen / Steve (...) using an offset. (...) Steve: From reading your code, it seems that you "recalibrates" the "zero" point very so often by assuming that the bot is vertical. So slow changes in reflectivity shouldn't matter. I've only been working (...) (20 years ago, 22-Jan-04, to lugnet.robotics)
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