Subject:
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Re: proximity detection with laser?
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 5 Jan 2001 21:42:25 GMT
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Viewed:
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666 times
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In lugnet.robotics, "Marco C." <marco@soporcel.pt> writes:
> One of the things I'm intending to do is to put two light sources in the
> robot and measure the distance between the (if available) two reflection
> "points" (or er... auras)
>
> It should work better with laser source, of course. But then, using laser,
> there would be no need for two. One vibrating horizontally, drawing an
> horizontal "fixed" length line could do the job. The length of the
> reflected line would give the aproximate distance.
>
> But, because a have no lasers, I thought of using the 1st technic.
>
> I haven't had the time (nor a camera) to test this. My camcorder was big
> and... errr... it's gone to the camcorders heaven.
In my current project, I mount a wireless camera on top of the mobile robot,
to look for barcode tags as the landmarks. The idea is: In the computer it
stores a topological map of the locations of each barcode tags. A typical
session:
I: Robot, go to barcode #5.
Robot: Ok. First I have to locate barcode #1... Good, now I have to
proceed to #2... Good, I will turn left here and proceed to #3... Oh, no!
Why is #6 here? I must have overshot. Now, turn around...
I am also using CyberMaster instead of RCX, because everything is done
off-board, and I need to maintain constant communication between the robot
and the PC.
However, CyberMaster does not support many types of sensors. For some time I
have been toying with the idea of switching to Handy Board, so I can have
more choices on the distance measuring devices (sonar, IR, etc.).
This is why this laser idea is so attractive to me. I have already had the
hardware and the off-board image processing software in place, and now I
just need to arm the robot with two additional laser guns.
> I intend to get a Vision Command (since I don't own a webcam) as soon as my
> new RIS 1.0 arrives.
>
> All the robotics stuff I've done so far was with a CyberMaster pbrick.
>
> As soon as I finish my project of CM<->RCX communication, I'll start
> working on this subject of distance measuring through vision. Be it with
> light/laser sources, or landmark analisys... whatever works best.
I am confused here.
On one hand, if your robot is now tethered to the PC (for the camera),
wireless communication is no longer important, so maybe you can switch to
RCX completely?
On the other hand, if you want to stick to CyberMaster, now the image goes
from the camera to the PC, then the PC sends commands to the CyberMaster.
Everything is fine. Why does CyberMaster need to talk to RCX?
> > In its simplest form, the laser beams out a single dot. The camera picks up
> > the position of the dot, then we calculate the distance to the obstacle by
> > triangulation.
>
> Wouldn't the "one dot" technic be more dificult to compute (and more
> inacurate) ?
I was thinking about those IR-based distance measuring sensors from Sharp.
(See <http://www.sharp.co.jp/ecg/opto/products/f-osd.html>.) They did it
with only one dot.
But of course you are right, two dots simply things a lot.
Cheers,
Hao-yang Wang
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Message has 3 Replies:
 | | CM-RCX comm
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| hi marco! so have you already managed to get a cm-rcx comm? or are you still waiting for an rcx? i'm highly interested in any details on this subject, cause i'm planning something similiar (using cm for it's radio link and rcx for it's extended (...) (23 years ago, 9-Jan-01, to lugnet.robotics)
| | | Re: CM-RCX comm
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| Hiya :) Well, I'm still waiting for the RCX... it's supposed to arrive in 4 weeks :/ Anyway, these are the things I got so far: 1) It's possible to use the OUTport->INport direct electrical connection *IF* one uses the Off() and Float() commands to (...) (23 years ago, 9-Jan-01, to lugnet.robotics)
| | | Re: CM-RCX comm
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| Some more clarifications: (...) The LightSensor can be used as a IN *and* OUT vll sensor, only the IN port's dedicated to bidirectional comms. (...) Lego Light or the Fiber optic light unit's LED (...) I meant IN port. (...) I keep making this (...) (23 years ago, 9-Jan-01, to lugnet.robotics)
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Message is in Reply To:
| | Re: proximity detection with laser?
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| (...) One of the things I'm intending to do is to put two light sources in the robot and measure the distance between the (if available) two reflection "points" (or er... auras) It should work better with laser source, of course. But then, using (...) (24 years ago, 5-Jan-01, to lugnet.robotics)
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