Ask a Mechanical Engineer: Motion Sensor Work Underwater?

[Mark14]

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!

 

[phinds]

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.

 

[billy_joule]

Doppler shift flow meters are one example of similar tech. They measure the velocity of bubbles or particles in fluids.

 

[siddharth23]

Yes there are underwater motion sensors. Like Billy said, their functioning is based on Doppler shift. Usual motion sensors use infra red.

 

[Baluncore]

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.