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distance measurement by ir sensor

Discussion in 'Electronic Design' started by houzad mshm, Jul 16, 2003.

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  1. houzad mshm

    houzad mshm Guest

    I am building a maze solving robot.I need to measure short distances,
    about 2cm to 10cm.It is usual to use ir sensors for time saving.
    Some manufacturers have designed ir distance measurment devices
    but they are too expensive.I wonder if I can design such a circuit
    with ir diodes and ir transistors.I will be greatfull if anyone can
    send me a good circuit diagram.
     
  2. Bill Sloman

    Bill Sloman Guest

    An autofocus system from a camera might do what you want, but 2cm to
    10cm is a little on the close side for these sorts of systems.
    Polaroid's ultrasonic ranging system was the first of these, and - in
    its time - was available separately. There was even a designer's kit.

    In your application, I'd expect the measuring principle to be
    triangulation - the IR source doesn't fire straight ahead, but is
    canted at a slight angle, and you have several ir-detectors, possibly
    a small array, behind a lens.

    You scan the array and the ir-detector that is looking at the
    reflected spot gives you the maximum signal. By interpolating between
    the maximum signal diode and the signal from the diode with the next
    most intense response you can get a continuous indication of distance
    to the reflector.

    There are a number of other ways of exploiting the same principle - by
    mechanically scanning your offset light source, you can get away with
    a single detector, which deals with the problem of matching detector
    sensitivity.

    I haven't got access to any circuit diagrams.
     
  3. Tony

    Tony Guest

    Is $10 to much. Check out the Sharp GP2D120 sensor.
     
  4. S.M.Taylor

    S.M.Taylor Guest

    T'was available from Polaroid last time I looked.

    Sharp do the SHARC sensor for short range IR distance measurement.

    Steve
     
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