Subject:
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Re: Navigation using landmarks (Was: Re: lasers and RCX)
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Newsgroups:
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lugnet.robotics
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Date:
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Mon, 24 Jun 2002 19:41:18 GMT
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Viewed:
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957 times
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"Steve Baker" wrote:
>
> I looked into several patterns. What would be ideal would be something • which
> you could drive across along any straightline path and get back your • direction
> and position from the pattern of dark and light.
>
> It seems rather unlikely that such a pattern could exist - but I havn't
> finished thinking about it yet.
Somebody in this list already tried a pattern with 4 colors. If you can
have all your floor covered with squares with 4 distinct colors, you can
detect your aproximate position and direction. Unfortunatelly that won't
work for me. I don't want to build a big mat or redecorate my apartment. :)
> Meantime, I settled for a pattern that could be approached from any • direction
> and then *followed* to lead you to a barcode that would tell you what you • need
> to know.
>
> > The main idea was to use a robot with rotation sensors on 2 wheels. • Starting
> > from a known position it would be able to turn and move with some • precision.
> > But there will still have some acumulated error due to slippery, • obstacle
> > avoidance, etc.. But it would be enough to move from one landmark to the
> > other.
I already built the robot (wheelchair style) with 2 rotation sensors.
Although it seens very precise to move in a straight line, sometimes it
changes its direction by a few degrees. It looks like one of the rotation
sensors is losing some counts. Some people already reported this kind of
problem. I'll debug to be sure. I may need to change the gears to reduce the
rotation sensor speed. The problem is that I will lose precision as well.
>
> Well, the idea is that there could be a straight section of line before • the
> barcode. Following that *should* allow the machine time to get nicely
> aligned so it can just drive forwards and still hit the barcode.
>
> What would make this easier would be if you had TWO light sensors - one to
> follow a line - and another to read off information. Then, you could just
> have a circle (to follow in a clockwise direction with a light sensor to
> the left side of your robot...and inside that circle, printed in a ring
> inside it, there could be a series of bar codes that would tell you your
> present heading. The robot could drive in a circle tracking the line -
> and just go off in a straight line once it had read off the heading it's
> looking for.
The robot I'm using already uses 2 rotation sensors. I have space for only
one more light sensor.
But I liked the idea. I'll think about another design with a single rotation
sensor.
I'll report my results later on this thread.
Mauro Vianna
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Message has 3 Replies:
 | | Re: Navigation using landmarks
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| (...) Mauro, sorry if it is obvious (I am anovice here) you could connect the two wheels' axles to a differential (reverse one of the rotations). If the differential's body is stationary, the two wheel are rotating at same speed. (22 years ago, 25-Jun-02, to lugnet.robotics)
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Message is in Reply To:
| | Re: Navigation using landmarks (Was: Re: lasers and RCX)
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| (...) I looked into several patterns. What would be ideal would be something which you could drive across along any straightline path and get back your direction and position from the pattern of dark and light. It seems rather unlikely that such a (...) (22 years ago, 14-Jun-02, to lugnet.robotics)
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