Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Need help with an idea!

  1. Jan 27, 2015 #1
    I was looking to get any advice from a mechanical engineer about motion sensors. Would it be possible to make a motion sensor work underwater? i wasn't sure if the water would interfere. Thanks for anything, if this isn't an appropriate place for this question i would appreciate if anyone has a better forum to ask on. Thanks!
  2. jcsd
  3. Jan 27, 2015 #2


    User Avatar
    Gold Member

    I'm not an ME and I don't know about different kinds of motion sensors but I can guarantee you that you can make an underwater motion detector with a combination of a video camera and software to detect changes in the image. This obviously would not work as the light got dimmer and dimmer at depths.
    Last edited: Jan 28, 2015
  4. Jan 28, 2015 #3


    User Avatar
    Science Advisor

    Doppler shift flow meters are one example of similar tech. They measure the velocity of bubbles or particles in fluids.
  5. Jan 28, 2015 #4
    Yes there are underwater motion sensors. Like Billy said, their functioning is based on Doppler shift. Usual motion sensors use infra red.
  6. Jan 29, 2015 #5


    User Avatar
    Science Advisor

    How is the water moving? What range do you require? How big are your moving targets?

    Waves would produce variable doppler shifts, a flowing river would produce a constant doppler shift.

    The echo of an ultrasonic pulse or chirp will depend on the position of nearby objects. If the record changes then the environment has changed.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook