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USB Laser Stripe Rangefinder

Using a laser to generate structured light for robot navigation is not a particularly new idea, but the recent availability of both cheap usb cameras and cheap laser stripers (in the form of various consumer grade laser levels and alignment tools available at hardware stores) make this one of the more interesting robot sensors in terms of resolution per price. This prototype consists of just a usb webcam, a laser diode/line generator, a LM317 to convert the USB's 5v power to 3v for the laser (it originally ran on two AA's) and some plywood and aluminum.



The computer processes the images by running a spatial bandpass filter on the red channel in the vertical direction and then taking the maxima for each column. More intelligent filtering techniques should yield better results. This screenshot shows the red channel camera output with the line highlighted and the resulting distance plot.


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