laser rangefinder/imaging???

SK8 4 U

Hi all...

Does anyone have any experiance with laser rangefinders?· I have been playing with the idea of using a rotating mirror - laser setup that is mounted on a rotating table to 'scan' the surroundings of a mobile robot.·With this poorly described setup, it would be possible to scan a hemispherical area from the top of a 'bot. ·Both the rotating mirror and the rotating table would be position controlled by a u-controller, and the imaging data would be wirelessly offloaded (for the time being) to a fast PC for image processing.· I have no designs yet, this is at the moment just a thought exercise.· I got the idea from the opening scene from the second Aliens movie, (belive it or not),·and therefore, the laser would have to be green!

Any thoughts on this would be very apreciated, especially if it would be completely impractical.·

All the best,

73
Joe
KB0TXC

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pjv

Hi Joe;

I have been working on a project interfacing a commercial laser range finder for data acquisition. This product (Disto is the name and costs a few hundred dollars) fires off a laser beam and captures a reflection, then uses time-of-flight to calculate the range distance to an accuracy of about 3 millimeters in a length of 30 meters in my application, although I believe it can go to 100 meters. To get this precision it takes an average of several sapmples, and gives very reliable and repeatable results. The speed is not great however, giving one average per 3 or 4 seconds. Controlling this with a micro could probably streamline this somewhat but I suspect such an answer is too slow for your needs, but the accuracy is great.

If I had to tackle your project, I probably would build my own unit and tailor it to your specific needs, sacrificing accuracy for speed. I suspect that one could get an adequate (20 milli meter?) reading as fast as every 10 to 50 usec. I would caution though that time-of-flight measurement at light speed is a complicated issue if any reasonable accuracy is required. Remember that light travels at about one foot per nanosecond, and sub nanosecond measurements take special techniques.

You will need to determine what your precision requirements are, and how many shots you need per second to determine if this technique is feasible for you. I suspect it might be a stretch.

Peter