Positioning equipment

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

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?

strobe/laser burst, light travel delay measurment?

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

^^^^^^^

Would this be for electromechanical placement of the appliqués? ;-)

Good Luck! Rich

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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.

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

BTW optical mouse may be better!

How come we didn't think of this? :) Great idea, thanks! I think we'll use it.

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.

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.

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.

I doubt optical mouse would be good becouse it doesn't work well in 3D. However, trackball might solve the problem.

What about a laser distance finder like surveyors use?

Bob Hofmann

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I suspect it will slip.

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More expensive than GPS ?

• it doesn't work well when there are some obstacles.

Indeed. I'm not so enthusiastic any more :)

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?