Robotics is now more accessible than it has ever been, thanks to the proliferation of affordable hardware and detailed information available on internet communities like our own. Submersible robots, however, present a number of unique challenges that can make them difficult to build even today. You have to ensure that the sensitive electronics are protected from the water, you have to contend with pressures that quickly become non-trivial, and even sending control and telemetry data through water can be a serious issue. That’s why Noeël Moeskops has been working on the Aruna project, which is an open source modular ROV design that you can build yourself.
A remotely operated underwater vehicle (ROUV) or remotely operated vehicle (ROV) is a special kind of submersible robot that is designed specifically for exploring oceans, lakes, and other aquatic environments. They might be intended for modest depths of just a few meters or extreme depths, as was the case with the Nereus that in 2009 reached a depth of 35,768 feet (10,902 meters) in the Challenger Deep within the Mariana Trench — a depth that was just barely exceeded later by a manned submarine. The pressure on a vessel at that depth is mind-boggling, but pressure can be an issue at any depth. Dealing with that pressure is a significant engineering challenge, which is why hobbyists should be excited about the Aruna ROV, because it streamlines the design process.
Aruna adheres to a dry tube design, which is fairly typical for robots like this. All of the electronics are held within a sealed and reinforced PVC pipe. It’s propelled by six A2212 930kV brushless DC motors, each of which is driven by a BLHeli ESC (Electronic Speed Control). The ROV is controlled by an ESP32 board, with code that supports a number of optional modules. Currently, modules exist for communications, logging, system status information, and, of course, control. Many other modules are planned or can be created by the user, including cameras, systems for collecting samples, and a variety of sensors. Aruna is still an in-progress project, but everything you need to build a basic ROV, including CAD files and code, is already available for you to take advantage of. Moeskops’s ultimate goal for Aruna is for it to fill the same role as Robot Operating System (ROS) does for ground robots and ArduPilot does for drones, and it’s looking very promising already.