Field Notes: A Tour of Mesobot's Guts

Dispatches from Bermuda

Getting Mesobot ready for a dip in the water is no easy feat. Designed to follow a single organism for the duration of its nightly migration, it requires a suite of motors, thrusters, a complex of electronics, and perhaps most importantly, intelligence--artificial intelligence--to read and respond to its environment. Orchestrating all of these mechanisms at once is made even more complex by the fact that they all have to operate simultaneously under extreme pressure in electrically conductive saltwater. That’s why it’s critical to test, retest and test Mesobot again and again long before it ever gets its first taste of ocean. In order to do that, OTZ engineers deconstructed it to work with all its components individually.

While they’re at it, you can take a peek inside with today's slideshow (below).

—Jennie Berglund, OTZ Field Correspondent

Load Control Boards (LCBs)

Pictured here are Mesobot’s load control boards (LCBs), which control how power is funneled to the system. They’re also a central hub for data coming from the robot’s various sensors, which are sent to an onboard computer system. Because they both control power and funnel data, they’re a great place to identify a problem because an engineer can go through and test each connection one at a time. (Photo by Evan Kovacs)

LRAUV Motherboard

Mesobot's load control boards might control its power, but the real brains behind its operation come from the motherboards. Pictured here is the LRAUV motherboard, which controls mostly basic functions like power and data gathering from various sensors. If Mesobot runs into trouble, it can also trigger what’s known as a dropweight burnwire, which literally cues a particular wire to burn, causing a weight to drop to the seafloor, which sends Mesobot to the surface. Below the LRAUV is yet another motherboard, the NVidia Jetson TX2, which controls some of Mesobot’s more complex features, such as its cameras and its motor control commands, and coordinating the motors for its thrusters, which propel it through the water. (Photo by Evan Kovacs)

Main Electronics Housing

This is the front end cap of the main housing for Mesobot’s electronics, with its brain and spinal cord, the chassis, bolted to the inside. The whole assembly slides into the cylindrical housing in one piece, stopping when there’s a little room left to connect cables to the rear endcap. The faces arex then cleaned and the o-rings lubricated, which keeps water out. Once sealed closed, the enclosure is vacuum sealed to double-check for leaks. If it remains sealed, it’s time to move on to the next testing phase...in seawater. (Photo by Evan Kovacs)

Engineer Jordan Stanway troubleshoots a problem in one of Mesobot's motors.

Checking Electronic Connections

Engineer Jordan Stanway tests Mesobot’s “brain and spinal cord”, the robot’s inner workings connected together on what is known as a chassis. Here, he is troubleshooting a problem detected in one of Mesobot’s motors, which requires him to go through a chain of electronic connections, rung by rung, to identify the culprit. (Photo by Evan Kovacs)

WHOI Senior Scientist Dana Yoerger uses an open-source software, VESC (Vedder Electronic Speed Controller), to calibrate Mesobot's motors.

Calibrating Mesobot's Motors

Just like a piano, complex electronic systems like Mesobot’s motor controllers need a fine tuning every once in a while. Here, WHOI Senior Scientist Dana Yoerger uses an open-source software, VESC (Vedder Electronic Speed Controller), to calibrate the motors so Mesobot can navigate precisely during its twilight zone journey. (Photo by Evan Kovacs)

WHOI Senior Scientist Dana Yoerger Dana Yoerger tests Mesobot’s thrusters.

Testing Mesobot's Thrusters

Here, Dana Yoerger tests Mesobot’s thrusters, and it looks like he’s having good luck since all the parameter estimates, the bars on his computer screen, are green. Behind the computer, you can see green lights indicating which wires and their connected sensors are receiving power. (Photo by Evan Kovacs)