Masters Project

Experiment in action
An experiment in action. The prototype VAP is attempting to follow the path shown in white.

In summer ‘22 I worked in DTU Aqua (a department in the Technical University of Denmark focused on marine research) as a research assistant. I was tasked with compiling a report on all the different ways you can collect data from the oceans around Greenland (in a fixed location). It was a great task, I got to speak with researchers and industry specialists asking them about how they had completed similar projects. I got to write python scripts to analyse forces in moorings and expected drifts of different concepts using historical current data.

While in this role, I came up with a new way to take these measurements. My idea was we could use a type of ocean glider AUV to move up and down the water column while staying in the same area, I called it the Virtually Anchored Profiler (VAP). DTU Aqua thought the idea was interesting, so I organised a collaboration between DTU and the University of Cambridge and continued investigating this concept as my Masters project.

I decided to investigate how to control the VAP in an energy optimal way, while ensuring that the VAP moves where it needs to. To do this I first built a prototype VAP, which had a movable brass mass (so the centre of mass could be changed) and motorised syringes (so the buoyancy could be changed). An ESP 32 controlled the device.

I wrote a Python program which allowed me to choose a control strategy. It computed the path the VAP should follow based on that control strategy. It tracked the position of the VAP using a webcam connected to the laptop pointed at the tank of water (this was quite involved, I had to undistort the image and define a space using these fiducial marker tags, for anyone looking to do something similar I highly recommend using fiducial markers, I used April tags).

labelled VAP design
Labelled prototype VAP
Prototype VAP
Close up of the prototype VAP. Note the angle on the fins. This allowed current to be simulated in a still water tank. When the VAP falls, a force acts on it due to the tilt of the fins exactly as a current would.

This program also calculated how the position of the centre of mass of the VAP and its buoyancy should be varied to follow the path. The error and amount of energy expended was calculated for each control strategy which allowed me to compare them.

My project was awarded a First Class Honours and was nominated by the Department of Engineering for the Institute of Mechanical Engineers best project prize.