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Ultrasonic Sensors

  1. Jul 24, 2006 #1
    Hi guys!

    have to build a hovercraft as part of a third year Eletircal engineering project. It must hover through a maze without touching the sides of the walls. I've decided to use ultrasonic sensors to measure distances as opposed to infra red (reason being - ambient lighting will pose big problems !!). Just a quick question - will i have big problems using ultrasonic in terms of the sound waves hitting the floor and bouncing back and thus not getting the desired result. In theory (or in my mind) the waves must just hit the wall and bounce back - then i can measure a distance using speed time distance formula. However will waves hit the floor and will these reverberations cause big problems or will they be negligible. If anyway can give me some sort of answer - it will greatly be appreciated.

  2. jcsd
  3. Jul 24, 2006 #2


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    That's a very difficult question to answer. It depends upon the directionality of your transducer (which produces the ultrasound) and the receiver (which detects it), as well as the characteristics of the material used to make the walls.

    You will get one strong echo from whatever's nearest your vehicle, but you'll also get numerous weaker echos, later in time, from longer paths -- say, bouncing off three or four walls before arriving at the receiver.

    Your circuitry must be able to differentiate the first, strong echo from later, weaker echos. If you're using a microcontroller, this might be as simple as programming it to ignore the receiver for a millisecond after receiving the primary echo. If you're using analog circuitry, it will require a rather different approach.

    - Warren
  4. Jul 24, 2006 #3
    Is your hovercraft supposed to traverse the maze on it's own?

    I had to do this project, except with a tank, in my AI class back when I was in college. We didn't have ultrasonic sensors, instead we had to use IR. My only advice is that there always seems to be some unknown variable when working with sensors. So be careful.
  5. Jul 25, 2006 #4

    chroot >> thanks - makes sense - guess i'll first have to build it and see what problems arise. Thanks!!

    buddyholly9999 >> thanks!
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