Surface Current Measurement and Route Optimization Using Autonomous Boats

Michael E. Holden

California State Maritime Academy Sabbatical Fall 2024

Overview

This report shares the results of my Fall 2024 Sabbatical project. It will get into the details pretty thoroughly, with links and files so I can find all the work in one place in the future, so feel free to skip around to the good parts. For a more visual feel you can follow the insta-blog at n3m0_the_robot_boat.

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n3m02 the Autonomous Boat: Depth Surveys

catamaran version of n3m0 the boat

This report documents the transition of n3m0 the autonomous boat, originally a monohull designed for long-ish range water-quality measuring missions, to n3m02 the autonomous catamaran. The mission was to add a depth sensor to the boat so that it could survey the harbor at Cal Maritime. The harbor silts in pretty quickly and it is an expensive and time-consuming process to dredge, so keeping tabs on the depth over time was the goal. A transom-mount NMEA-1083 speed/depth/temperature transducer was added to the boat, and a raspberry pi was used to log the position of the boat from the autopilot and the depth from the sensor. The data was uploaded in real time to github, which worked quite well! Eventually a second hull was added to allow differential thrust and improve maneuverability when running next to docks and moored vessels. Read on for more information!

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Super Simple Automatic Chicken Coop Door

Pet chickens like to run around and scratch up their yard during the day, but must be safely locked away at night to prevent predators from eating them. Most chicken-keepers accept the twice-daily chore of letting the hens out in the morning, and locking them up at night. This is a project to automate that task using an inexpensive sensor, an arduino microcontroller, and a linear actuator. As a bonus this project runs from a solar-charged battery!

This project is pretty hacky looking or you could say it has an agricultural feel to it, but it’s been running solid for over a month so I thought I would record it here. Bring on the bailing wire!

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Electronic Windvane

This project documents how to make a windvane to sense the wind direction. It was designed for an autonomous sailboat but could be used in other applications. The structure is mostly 3D printed and uses a gopro mount to attach to the hull. The main sensor is a magnetic encoder that outputs an analog voltage in the 0-5V range. For my application I used a voltage divider to bring that down to 0-2.5V because my autopilot is based on 3.3V logic. I also have an arduino program to output the vane angle as NMEA 0183 serial data; I don’t use this on my boat but it is a standard digital interface that might be helpful for others.

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Internet of Coffee!

Monitoring the morning brew with the internet of things.

Hot Coffee (sped up 40 times)

Do you want to know when your coffee is done brewing but are too lazy to walk over to see for yourself?  Do you need to monitor your coffee pot when you are out of town?  Probably not, but here is one solution to the non-problem.  CLICK HERE to see if the coffee is hot, or keep reading to see how to make your own.

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Dumbo the Autonomous Boat

Dumbo is an autonomous research vessel constructed by students at Cal Maritime.  Dumbo carries temperature, salinity, and dissolved oxygen sensors and makes oceanographic observations in the waters off of the Cal Maritime Campus.  This work has been supported by the CSU Council on Ocean Affairs, Science & Technology (COAST).

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n3m0 the autonomous boat

autonomous boat
n3m0

n3m0 is a small 3-D printed autonomous boat.  It was originally documented over at hackaday.io as part of the hackaday prize contest.  It’s been used for a number of projects since then, mostly documented on this website, such as n3m02 the Autonomous Boat: Depth Surveys, Ardupilot with Mobile Data Telemetry, and Surface Current Measurement and Route Optimization Using Autonomous Boats.

The project page.

I won $1000 in the hackaday prize! Actually $2000!

Feature on hackaday.com

Feature on hackster.io

Someone else is already building another one

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