# Positioning equipment

Discussion in 'Electronic Equipment' started by Qweertz, Nov 2, 2007.

1. ### QweertzGuest

Hi,

my teammates and I need to develop some device on one of our collage
courses. One of it's features is to be able to determine it's position
relative to it's start position. Distances could be up to 1 kilometer and it
the price - it should be as small as possible. GPS is too expensive.
We thought of placing three sticks somewhere in area and then to transmit
radiowave or ultrasound from our device to them and to measure distance that
way, but we don't know how much would this cost.
Does anyone have some better idea or at least knows how expensive would be
our idea?
We're new in this area so I appologize if this question seems stupid to
someone.

2. ### Brendan GillattGuest

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
I highly doubt you will get 10cm in 1Km accuracy with something costing
less than a \$60 GPS module O-o

- --
Brendan Gillatt
brendan {at} brendangillatt {dot} co {dot} uk
http://www.brendangillatt.co.uk
PGP Key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0xBACD7433
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.3 (MingW32)

iD8DBQFHK3GakA9dCbrNdDMRAll5AKCm+RQOqSYb5ZRpSJrnRiRo4M77uQCgxtR9
FM1nvDs3DqizJq7s+1vXJqI=
=ZizA
-----END PGP SIGNATURE-----

3. ### JeffMGuest

They must be making more complex projects down at the Rec Center.

4. ### poogieGuest

First, I do not think you need three anything. Only two for x and y.
you need to be more specific in what you are trying to determine. Is
it a mechanism which runs on the ground and after time you need to
determine where it is? Do you need to know elevation? The doppler you
suggest may have some echo problems. What are you allowed to have as
far as equipment?

5. ### HapticZGuest

strobe/laser burst, light travel delay measurment?

FM phase/loran type xmit/rcvr (old stuff!) accrate over time,bad short
term though

6. ### Rich GriseGuest

Would this be for electromechanical placement of the appliquÃ©s? ;-)

Good Luck!
Rich

7. ### QweertzGuest

Hi,
Our device will move accross some field and it should cover whole field (it
should pass over every inch of field). There are no limitations considering
shape or elevation of field and there can be a lot of obstacles (walls,
trees etc.). There are no limitations in using any kind of equipment, but it
should be as cheap as possible.
I think it would be very difficult to use doppler becouse of the obstacles.

8. ### poogieGuest

With this information my suggestion would be very inexpensive. I would
get a computer mouse or better: a track ball mouse and use the guides
in it to put over say a basketball. Secure the rollers on a bowl
allowing them to run over the surface of the b'ball. This will provide
everything you need. A little software calibration on a laptop would
provide the accuracy. By rolling the ball the cursor would move
accordingly. You could then load the data into a 3d modeling like
excel and have a replica of the area covered. I would be cool if you
used google earth and calibrated it with that. There is also a
distance tool there. I do not know if it zooms to 10 cm.
Hope this helps
Poogie

9. ### poogieGuest

BTW optical mouse may be better!

10. ### QweertzGuest

Our device will move accross some field and it should cover whole field
How come we didn't think of this?
Great idea, thanks! I think we'll use it.

11. ### QweertzGuest

strobe/laser burst, light travel delay measurment?
This is something that came first on my mind but it's quite expensive and I
don't know how good can it work on area of only square kilometer.

12. ### Wim LewisGuest

I'm not sure you'll be able to do better than GPS for an area that large,
since GPS receivers have gotten fairly cheap --- \$60 - \$70 including antenna.

Can you invert the problem? Place a camera on a platform that overlooks
the whole area. Put a light on each device that blinks at a prearranged
time. The camera looks for the blink and is calibrated so that you can
deduce the position of the device from its location in the image.

13. ### QweertzGuest

my teammates and I need to develop some device on one of our collage
This could be problematic becouse device would have to move across a lot of
different fields and it would be too complex for end user to find right spot
for the camera. If modified trackball won't work, we'll buy GPS.

14. ### QweertzGuest

Our device will move accross some field and it should cover whole field
I doubt optical mouse would be good becouse it doesn't work well in 3D.
However, trackball might solve the problem.

15. ### hr(bob) Guest

What about a laser distance finder like surveyors use?

Bob Hofmann

16. ### CWattersGuest

I suspect it will slip.

17. ### CWattersGuest

More expensive than GPS ?

18. ### QweertzGuest

Our device will move accross some field and it should cover whole
+ it doesn't work well when there are some obstacles.

19. ### QweertzGuest

Indeed.
I'm not so enthusiastic any more

20. ### terrySGuest

This is a technical subject! No need to be able to spell!
That will come later when it is necessary to make presentations to
management groups and investors?