NEMO, or Noyo Educational Marine Drop Camera is a underwater camera and instrument platform designed to be deployed off a small boat in the ocean. It is capable of reaching depths of 300ft deep. It was developed for Noyo Center for Marine Science, https://noyocenter.org/ as a volunteer project of myself and Velocity, the Fort Bragg High School Robotics Club. Noyo Center is a small non-profit Marine Science Center on the coast of northern California. They have regular trips to sea for the youth and adults, NEMO was designed to allow people to get a first hand live experience of the sights of the underwater world. Additionally NEMO carries instruments to measure depth, temperature, water current velocity, pH, salinity, dissolved oxygen and a sensitive hydrophone.
The NEMO system consists of 3 main parts. The underwater vehicle, a tether, and the surface control unit. The vehicle presently relies on one Arduino Mega 2560 with a custom shield and an additional Uno for the instrument module that measures O2, pH and salinity. On the surface side, a Mega 2560 with custom shield provides topside processing power with an additional Uno and video shield to do all the video data overlay. Power for the vehicle is provided by a custom lipo battery pak and lead acid battery for the surface control unit. The tether is a heavy duty cat5 cable passed thru a polypropylene braided rope and also has a kevlar rope to provide strength to support the weight. The vehicle weighs about 35 to 40lbs dry and is ballasted to weigh 5-10lbs in water. The tether has 4 twisted pairs, one each for composite color video, RS-485 telemetry, hydrophone audio and the forth used to remotely switching the vehicle on and off.
The frame of the vehicle is made from custom cut HDPE, while all internal plastic parts were 3d printed from custom designs. This includes parts for both pan and pan/tilt camera, lipo battery pack, pan light, and circuit board mounting. The pressure housing and endcaps are from BlueRobotics.
In summary, this project has been a great learning experience for myself and the youth involved. Designing all of the custom parts and integrating all aspects of the system to function accurately and reliably in the harsh ocean environment has been challenging and rewarding, and FUN! And thank to all those folks out there who write all those libraries for Arduino, it makes life sooo much easier for us.