I am interested in building a distance meter that interfaces through a laptop or computer, can measure distance from a few inches out to about 4 or 5 feet with a +-0.5% accuracy, fairly repeatable, and can measure off wood, metal, plastic and concrete. I was reading through the forums for the available technology and it looks like ultrasonic (ex. devantech ultrasonic range finder) and infrared (ex. Sharp) sensors are the two options. The problem with those two technologies was the accuracy was not up to spec.

Just doing a search for distance meters on the web I found the following items:

http://www.cstberger.com/Products/La.../LM_TLM200.htm

http://www.leica-geosystems.com/cpd/.../lgs_29794.htm

Both of these are closer to my required accuracy spec. What kind of sensors are these two items using, is the technolgy commercially available, and is it possible to build a rudimentary bench test setup for proof of concept? I don't necessarily want the cheapest option so don't worry about money. It would be nice to find something like the Phidget line that interfaces with the computer easily and has its own API but that is not required. Any information anyone could profide would be helpful.

Thanks

 

You might have a look at Banner Engineering's measurement units:

http://www.bannerengineering.com/pro...php?group_id=3

The LT7 looks like it might work for your range and accuracy.

Ken

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"To invent, you need a good imagination and a pile of junk."
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KMoffett-

Thanks for the reply. I took a quick look at that brand. The minimum range listed for the LT7 is 0.5 meters, which isn't quite close enough for the measurement range I need. I appreciate it though.

 

Ultrasonic tranducers are common in applications like this, and the closest you can generally get is limited by the generation of the signal before getting the echo.

I wouldnt mind getting further into it myself, and from what I've read in the past, most ultrasonic sensors work in the range of 40Khz.


So if you create a burst containing a 40Khz PWM signal, then record the time it takes for the echo to be recieved, then you know that Distance = Time * Speed

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Spency.

PIC Micro's - Your mind is the limit

PIC's and interfacing with other devices - a PIC Basic Guide @ digital-diy.net

 

Well I just found a device that ranges 6 inches to 254inches (with a 1 inch resolution)

http://www.maxbotix.com/Maxbotix__Bu...html#Order_EZ3



If you read the datasheet, it goes into more detail on the ultrasonic side of things

__________________
Spency.

PIC Micro's - Your mind is the limit

PIC's and interfacing with other devices - a PIC Basic Guide @ digital-diy.net

 

try http://eddiem.com/projects/chirp/chirp.htm for a cheap solution. I've only used the pocketpc version and it seems to work quite well.

 

When I click on the link I get a 'this site has been disabled' error

__________________
Spency.

PIC Micro's - Your mind is the limit

PIC's and interfacing with other devices - a PIC Basic Guide @ digital-diy.net

 

http://www.freewarepocketpc.net/ppc-...rce-v1-19.html is a site for the pocket PC version, the other site worked the day I posted the link.
You may be able to find the PC site from there or reuse PPC code as it really isn't too different.