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Laser range monitoring of your car

Catwell
Worried about my car parked on the street, I had an idea. A laser range finder that detects when my car is moved. Just point it out of the window with the car in view, and you are all set.
 
I know what you are thinking, why not monitor all activity in the car and send alerts? Well, in my case over the weekend, I was on the 27th floor of a building, and sending a signal might be difficult. My door remote wouldn't work from the building. How about sending a txt message from the car with alerts? I don't want to get a cell plan, just for my car. I know there are plenty of options, but let's stick to the range finding method.
 
The microcontroller aspect is easy enough, but I do not know where to begin with lasers or laser range finders. All I plan on doing is taking a distance sample from the laser every few seconds. I am hoping for a module that could tie easily to a mcu. From experience, does any such laser exist?
 
This idea could work if you want to detect is anything moves; other cars, garbage cans, garage door, other doors, random objects, homeless guy in the ally.
 
I sense that complete life monitoring will soon be ported to our phones. I would personally welcome that. A little piece of mind would be nice.
 
Cabe
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  • 0 in reply to Catwell

    Hmm. Depends how the distance is measured with the laser ranger. I brushed over this topic a while ago out of interest (in hobby robotics).

    So far as I know, the cheap laser distance meters actually use ultrasonic to get distance, and a visible laser to show where you are aiming.

     

    Actually using the laser is going to be more difficult. To quote Wikipedia (Sorry), there seem to be three common technologies to do this:

     

    Time of flight - this measures the time taken for a light pulse to travel to the target and back. With the speed of light known, and an accurate measurement of the time taken, the distance can be calculated. Many pulses are fired sequentially and the average response is most commonly used. This technique requires very accurate sub-nanosecond timing circuitry.

    Multiple frequency phase-shift - this measures the phase shift of multiple frequencies on reflection then solves some simultaneous equations to give a final measure.

    Interferometry - the most accurate and most useful technique for measuring changes in distance rather than absolute distances.

     

     

    The time of flight was the intuative method to me (from working with ultrasonic measurement), but youd need some speedy circuitry! (MCU fast enough?)

    I presume one of these techs have been used in the FLUKE.

     

    Also, this looks like a nice method (using machine vision). I fancy trying this with OpenCV at some stage.

     

    I'm no expert at all - just my 2c.

  • 0 in reply to e14 Contributor

    Robert,

     

    I considered using ultrasonic for this idea. But, the city streets are loud, and having dealt with untrasonic in the past, I know it could get distorted. Also, I wonder how the hundreds of dogs in the building would handle it.

     

    Excuse my ignorace in laser technology, but could this laser project/reflect 500 feet?

     

    Cabe