As part of the training programme for Bumblebee, first-year prospects are tasked to build an Autonomous Underwater Vehicle (AUV) from scratch to participate in the Singapore AUV Challenge (SAUVC).

I was in the Electrical team, specifically doing Acoustics. One of the challenges in SAUVC consisted of a row of buckets on the pool floor where one of them contained a 45 kHz pinger, and the AUV had to locate and drop a ball into it.

Hence, I built the AUV’s acoustic positioning system to determine the azimuth and elevation of the underwater pinger. Although the final robot run did not tackle this mission due to other issues, bench tests and testing from collected data showed the system was able to locate the pinger to within ~1 degree of accuracy. Hence, I found this to still be worthy of documentation and the sections below detail the development of the acoustic system’s hardware and software.

As the co-lead of the Electrical team, I also oversaw the design of the overall electronics stack of the AUV, so the broad considerations for the overall electronics stack are also covered in the last section.

Hardware

Overview, hydrophone model

Hydrophone Array

Linear, triangular, tetrahedral

Distance, aliasing (link to bottom)

Placement on robot consideration (wires too)

Electrical

Architecture

drawio to the rescue

Filter PCBs

problems faced with the frequency

Motherboard PCB

Motherboard PCB, placement, power

Software

Overview

Why phase D over TDOA

ADC Polling

ff

Sliding DFT

ff

Sinusoidal Regression

ff

Phase Difference Positioning

ff

Results

bench test simultaneous wave, data log

understandably not the most convincing stuff here but o wells

AUV’s Overall Architecture

pic, main considerations: ease of maintenance, ease of use —> wiring (lessons learnt from intern??)

Conclusion

A regretful loss of interdisciplinarity.

Going from small to big:

• acoustics: brain breaking but definitely classifiable as type 2 fun considering I genuinely learnt some new things
• electrical: worked with a big team but quite smooth sailing considering the overall architecture and goal was set clearly from the start + healthy number of motivated people = most deadlines met on time with very few major faults during testing phase
• whole thing: see sentence above. mech-elec-software split quite rigid, missing whole point of what makes robo special .-.

Programme intention not to win but to learn —> winning-training dichotomy .-.

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