Subject:
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Re: GPS Reality?
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Newsgroups:
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lugnet.robotics
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Date:
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Mon, 11 Apr 2005 14:15:39 GMT
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Viewed:
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1193 times
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A solution I suggested on the DPRG list was that if radio telemetry is
being sent to and from the robot, then to have each robot with a
clearly identifiable dot- rather like a police car - on the top. You
could then have a camera covering the arena, and a desktop machine
with visual processing software to work out the relative position of
the dot, then communicate this back to the bot with the telemetry.
However - this would only work in a very small space.
Also - it would limit the choice of colours, as Lego colours tend to
be very saturated colours, which are what this technique normally uses
to find stuff. We are back to visual processing now - but at least it
is now taken off the bots.
Another idea is to have an infra-red emmiter on the robot, and (in a
relatively unobstructed arena), sensors along the two horizontal axes.
Each robot broadcasts a different ID, and the arena systems use the ID
along with the sensors getting the clearest signal to send the robot a
radio signal back with the ID of the sensors or full coords. The
problem is that this approach needs a lot of sensors - its off the top
of my head, and I get the feeling dealing with multiple IDs while
doing strength comparisons from that many sensors may not be
particularly easy. This could be reversed with IR LEDs each
broadcasting a narrow beam coordinate along the side and front/back of
the arena- and the robot using this to infer its position by
differentiating the strongest signals. If the robot had a wide sensor,
while the beams were quite tight - that might actually work. But again
- you need a lot of beams, and a relatively unobscured arena.
Yet another is to use three Ultra-sound beacons again, but modulating
the ultra-sonic signals to include a time code - I get the feeling
that this may be too hard - although it is closest in function to what
you actually get from the GPS satellites.
The thing is - it is worth taking for granted that most of the
solutions will require specialist equipment in the arena - which
considering GPS relies on the satellites - is not an unreasonable
requirement.
Danny
--
http://orionrobots.co.uk - Build Robots
On Apr 11, 2005 2:14 PM, PeterBalch <lego-robotics@crynwr.com> wrote:
>
> > three sonar beacons,
> > which are broadcast a radio ping, and then transmit each of their • signals.
> > The bot controller than uses the time difference between the request • radio
> > ping, and the sonar reply to work out its position.
>
> So the robot works out it's best guess from the three intersecting circles.
>
> Of course, the radio signal is not strictly neccessary. Beacon A broadcasts
> it's beep. Beacon B hears A, waits a fixed delay then broadcasts it's beep.
> Beacon C hears A, waits a longer delay time then broadcasts it's beep. Etc.
> The robot hears the beeps (in order A, B, C, ... because the delays are
> long enough). It works out it's best guess from the intersecting
> hyperbolae.
>
> > JB: I've worked with a number of "solutions" but none of them are
> > anything I'd recommend.
>
> What's the best you've see so far?
>
> Peter
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Message has 3 Replies:
 | | Re: GPS Reality?
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| I'm a lurker, so apologies for jumping into your conversation. I believe iRobot patented an interesting system last year called 'Polaris' or something similar which used the principle of navigating by the stars to position a robot platform in an (...) (20 years ago, 11-Apr-05, to lugnet.robotics)
| | | Re: GPS Reality?
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| (...) With a cheap digital camera (say 800x600 resolution) with a 2.5meter ceiling (around 8') looking straight down through a typical 60 degree field of view lens, you're limited to an area about 2m wide by 1.5m wide...less if you are working on a (...) (20 years ago, 12-Apr-05, to lugnet.robotics)
| | | Re: GPS Reality?
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| (...) This may be a use (finally) for the spybot controllers. at least for those of us who try to stay purists. I can see that when it is in beacon mode that the LED is flashing, but i'm not sure due to lack of equipment that the different (...) (20 years ago, 23-Apr-05, to lugnet.robotics)
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Message is in Reply To:
| | Re: GPS Reality?
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| (...) signals. (...) radio (...) So the robot works out it's best guess from the three intersecting circles. Of course, the radio signal is not strictly neccessary. Beacon A broadcasts it's beep. Beacon B hears A, waits a fixed delay then (...) (20 years ago, 11-Apr-05, to lugnet.robotics)
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