Subject:
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Re: localization (was re: GPS)
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 12 Jan 2006 14:59:46 GMT
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Viewed:
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2068 times
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In lugnet.robotics, Roger Glassey wrote:
> Hi John,
> A localization scheme I have used with the RCX is uses the angles between light
> beacons in known locations, measured with a rotating light sensor. Two angles
> (3 beacons) are enough to calculate, with a bit of trig, the robot coordinates
> and heading. The robot needs to know its position and heading accurately
> enough to correctly determine which beacon is represented by a peak in light
> intensity.
> The accuracy of the scheme depends on the angle sensor accuracy and the geometry
> of the robot position relative to the beacons. I localize the robot to within
> about 8 inches, with beacons at the corners of an 8 x 16 foot rectangle.
> The new light sensor that can distinguish colors with a stepper motor should
> make the problem easier.
I also played with a light beacon system, but with a twist. Well actually two
twists. I used small pieces of "rear view mirror repair kit" mirror to make some
45 degree rotatable mirrors. These mirrors were used to make beacons with
counter-rotating beams (rotating in a horizontal plane) from highly directional
LEDs. The beams are set to face away from each other north/south for example and
coincide (as they pass each other) east/west. This means placed adjacent to a
north wall, two pulses of light are seen as each beam sweeps by the observer.
The timing between the two pulses is dependent on the observers angle with
respect to the beacon and each beacon can be constructed with a slightly
different beam rotation rate so the beacons can be identified. You do need to
know approximately where you are to know where to look to see each beacon, but
if you localise at regular intervals, this is not a problem. I played with this
scheme the year the original Mindstorms RIS product came out as one of the first
projects I did with it.
.... and I'm still having fun!
JB
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Message is in Reply To:
 | | Re: localization (was re: GPS)
|
| Hi John, A localization scheme I have used with the RCX is uses the angles between light beacons in known locations, measured with a rotating light sensor. Two angles (3 beacons) are enough to calculate, with a bit of trig, the robot coordinates and (...) (19 years ago, 12-Jan-06, to lugnet.robotics)
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