Simulations

By Dermot Tynan, over 5 years ago.

Carpenters like to say "measure twice, cut once." In the software world, we make extensive use of unit tests and end-to-end tests. But the North Atlantic is no friend to small boats, and there's not a lot of end-to-end testing which can replicate the vagaries of the wild Atlantic. To that end, we use simulations. Simulators can be used to throw all kinds of real-world problems at a piece of software, and measure the response.

• May 15, 2019
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How to fill a bath

By Dermot Tynan, over 6 years ago.

It seems straightforward enough to fill a bath. We know how to do it instinctively, but how do we program a computer to do it?

Let’s start with some assumptions. Assume we have a hot and cold tap, and we can control the flow on each tap. Also assume we can measure the average temperature of the water in the bath tub. Finally, assume we can measure the height of water in the bath. This last one is so we know when we’re done.

We’ll denote t as the measured temperature and l as the measured height of water. For that matter, we can refer to h as the amount of hot water, where 0.0 ≤ h ≤ 1.0 and c as the amount of cold water, again in the range 0.0 ≤ c ≤ 1.0.

Ultimately, we’re going to use a PID Controller to do the actual hard work of adjusting the taps. But before we get into that, we need to refine our equations just a bit, and also learn how to walk before we try to start running. (See what I did there? Running? Bath? Oh, never mind).

• April 3, 2018
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Rudder Movement Test

By Dermot Tynan, over 7 years ago.

I have uploaded a video (to YouTube) of the rudder mechanism on Hull #1 working from end-stop to end-stop. (Excuse the video quality, I used my phone to record it.)

I connected an Arduino (Mega2560 if you want to know) and a SparkFun stepper controller to the stepper motor which drives the rudder. I wanted to exercise the tiller gears and the rudder shaft for a while. The video shows the rudder swinging from almost completely to Starboard, all the way back to Port.

• April 27, 2017
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Robotic Sailboats and Airborne Viruses

By Dermot Tynan, over 3 years ago.

One would think that a global pandemic would be a great opportunity to hunker down and get some work done on one or other robotic sailboats. Unfortunately, this hasn't turned out to be the case. I am still knee-deep in hull work on boat #2, the main entrant. However, due to lockdown restrictions, I can't physically access the hull and so it has spent most of the last twelve months, waiting for more sanding and filling (side note: never let anyone tell you that you can "fix it at the sanding/filling stage"). But it's not all bad news. The lockdown has been good for boat #1, the test vessel.

• March 16, 2021
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