Is a GPS-sensor for the NXT possible?
From robots.net I caught this story about the World's Smallest GPS module, recently announced by Epson. The new chip is 7mm x 6mm x 1.28mm, so I wonder if that would leave enough room inside a typical NXT-sensor housing to fit the electronics required to have it interface with the NXT.
Does anyone know of any homebrew GPS sensors for the NXT?
What could you do with a GPS sensor on a robot?
Rob
Does anyone know of any homebrew GPS sensors for the NXT?
What could you do with a GPS sensor on a robot?
Rob
Comments
Ideally, I' like this to move up to a LEGO-class entry for the SRS Robo-Magellan event:
http://www.robothon.org/robothon/challenge.php
But I can think of other uses, including robot cooperation (knowing where the other robts are is an important part of this... think "swarm mapping"), or tracking a runaway pet (or child). Originally I was thinking about using a BT-equiped GPS unit to communicate directly with the NXT, but that's hard under NXT-G due to the specific format of the NXT-G BT messages.
http://www.engadget.com/2006/12/08/emtacs-new-mini-s3-bluetooth-gps-receiver-is-smallest-yet/
(wow that's too long a URL...)
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Brian Davis
You feed into a NTX subroutine a list of GPS coordinates and have your NTX system navigate to the coordinate list. Using either a differential or 2-3 GPS receivers you can deal with the position resolution...and once you get to your approximate end point you can use the ultrasonic component to triangulate into the target.
I think it is great that a tiny GPS component is available!!
The other problem I think is how to process so much data. GPS is a constant stream of serial data. The NXT has no change to capture that info. He is just to busy with other things. 1 way to solve this is to make a microproc that handles the GPS reciever and put's some data into a memory that can be resolved by the NXT. Even than GPS hold lot's of data. If you only look to what a GPS location looks like: N52 19.059' E6 31.950'
This is a Waypoint. That is a lot of info if you compare it to the ouput of a simple digitale sensor that only ouputs a variable between 0 and 255.
And even than the NXT would have a large terain for GPS to work. Because GPS is not very accurate in a area 10x10 meter (30x30 feet) If a GPS reciever is accurate by 2 or 3 meter you have a very expensive reciever. Normal recievers for car GPS use have something like 10 meter accauracy.
The chip size is not an important factor - this part and similar ones are currently shipping in a package of 4 times the volume.
The gateway question is what would use it for? An outdoors accuracy of 10m E-W and N-S, and much worse vertically, is good for a pilot or driver finding a landmark. Probably not fine enough to be useful on the scale of a typical Lego robot.
Of course you can try to configure a differential GPS setup. However Lego robots like to be in doors, away from puddles, big plants and the local wildlife. GPS does not like the indoors, presuming it can get a fix the flat surfaces of walls and floors can cause reflections and can mess up the accurate timings required.
Brian - these i.c. mostly does the signal processing. It certainly requires external components such as an antenna!
Apart from these little details a GPS receiver is straightforward. :-)
Happy Christmas all.
Tony N
but you need a BT connection. I use Icommand 0.5.
When I have any result with This experiment, I will post the documentation.
JAB, Juan Antoino Breña Moral
http://www.juanantonio.info/
As to the cost of a GPS unit, yes, this isn't insignificant... but considering how much some of us are willing to spend on "toys", I don't think it's out of range either. The GPS add-on for the PSP is under $100 I think, which is practical for many of us. The datastream isn't too bad either - most GPS units can be "pinged", and only send information when requested. As to needing a lot of information to transmit, a Lat/Long set is just two numbers (and not very long numbers at that). Even if the GPS unit sends them as text strings, with all the charecters, that's just string parsing. Not a terminal problem by any means.
From the standpoint of differential GPS, yes, this is how I'd suspect it would be best used: thank of two seperate robots that "leapfrog", so that one is always stationary to provide a reference for the readings from the first (and with BT, having two robots coordinate is very simple).
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Brian Davis
(who has watched GPS units with selective avalibility turned *on* still locate a point in space to within centimeters... differential GPS is fun)
I'd think a good solution may be a Hall sensor 'looking' at a compass needle on the robot to detect North, south whatever.. AND go on from there.