Autopilot performance comparison

[baladin]

Hello, 

I have been using the tinypilot on my boat (a 30 ft Albin Ballad) for 2 years, with success. (thank you to Sean and the community for this amazing tool ??)

I am considering using it on a fast 30ft trimaran, and I would like to ask who has experience using the pypilot on performance, light, or "fickle" sailing boats (light multihulls, mini 650, class40...) that need "dynamic" steering. 

Currently, I have a Raymarine EV-100 which is not satisfying at all. It doesn't work well over 13-14 kts or if there is swell, and the electric consumption is very high. 

More generally, how do you think Pypilot can compare to commercial autopilots used on racing boats (NKE, Madintec, B&G H5000/Hercules...)? Has anybody ever done "autopilot benchmarks"? 

Eventually, I noticed the tinypilot github repo has not been updated for a while. Does it mean does the pypilot version has reveiced upgrades that the tinypilot doesn't have? 

Looking forward to sharing with you! 

Nicolas

[Jean-Marc Douroux]

Sean a un trimaran qui ne doit pas être trop lourd mais contrairement à beaucoup d'entre nous, il utilise un drive plutôt rapide
Personnellement, je trouve que les bateaux les plus difficiles à barrer sont plutôt les anciens bateaux performants qui roulent au portant sous spi. Je régate en solitaire avec un superchallenger qui demande beaucoup de mouvements de barre sous spi avec de la grosse houle. Pypilot s'en sort bien. Sean a très bien expliqué le principe des réglages dans le manuel qu'il a mis sur le site pypilot.org. Quand on veut aller vite dans des conditions difficiles, le réglage DD est important. De la même façon, dans son manuel Sean explique l'importance de la vitesse du drive qui est très importante si on veut faire bien marcher le bateau.
La plus récente image stable de tinypilot est sur la page de téléchargement de pypilot.org. C'est pas la peine d'aller dans github. Elle permet de gérer plusieurs configurations de réglages des gains et des paramètres du contrôleur.
C'est difficile de trouver mieux

English
Sean has a trimaran that shouldn't be too heavy, but unlike many of us, he uses a fairly fast drive.
Personally, I find the most difficult boats to steer are older, high-performance boats that sail downwind under spinnaker. I'm racing single-handed with a superchallenger that requires a lot of helm movement under spinnaker in big swells. Pypilot handles it well. Sean has explained the principle of tuning very well in the manual he posted on pypilot.org. When you want to go fast in difficult conditions, the DD setting is important. Similarly, in his manual, Sean explains the importance of the drive speed, which is very important if you want to make the boat run well.
The most recent stable image of tinypilot is on the pypilot.org download page. There's no need to go to GitHub. It allows you to manage multiple gain and controller parameter settings.
It's hard to find better.

[seandepagnier]

I used pypilot quite a bit on my kracken 33 trimaran. It performed well at all boat speeds for me, but there is always room to improve.

The biggest improvement is I used a high speed actuator that moves 150mm/s. This rotates the rudder 30 degrees per second. Most corrections are for fractions of second but the fast movement makes a big improvement. I reduced the servo.period to 0.25 and tweaked some other settings to make it react quickly.

Slower actuators that moved half this speed were fine in lighter wind but never steered as well once I exceeded 8 knots. This might be the issue with other autopilots too though pypilot likely outperforms raymarine by a good margin anyway.

There are not many direct comparisons to other pilots but so far in all but 1 or 2 cases the results are that pypilot performs better. There are a lot of variables involved. I expect the more advanced pilots you listed to potentially have an edge in some conditions but without their source code or algorithms it is difficult to say. I have received reports that pypilot outperformed a b&g pilot. Again it really depends.

As for racing in big swells... This is tough. Because relying on the autopilot could even be dangerous. My trimaran was built in 1973 before they put enough buoyancy in the outer hulls so I was nervous to push it, especially downwind as this is a known capsize risk when it is surfing and a hull digs in. I felt comfortable sailing 12 knots on a reach and occasionally would go 14-15 knots but my sails were original from the 70s and had poor shape (making autopilots for years kept me too poor to upgrade) so the performance was limited.

downwind I would typically slow down to 9-10 knots with swell. Newer designs of trimarans should be much safer. It would be interesting to perhaps have additional safety logic in place but I am not really sure what is best. Perhaps a rocket on top of the mast can be used to right the boat if needed. But more seriously an additional computer with sensors that can do something to prevent capsize. This was always my biggest fear as I managed to bury (submerge a hull completely) or roll to 45 degrees in the gulf stream.

The pypilot repository is for the autopilot and has more recent improvements but recently not many unfortunately. As for tinypilot this is just the base operating system built on tinycore linux so it has not needed many updates.

[baladin]

Thank you very much for your answers!
Sean, which high speed actuator model do you use? Or which one would you recommend?

[Jean-Marc Douroux]

In the manual posted on the documentation page, Sean made some very good recommendations in addition to explaining precisely what he installed on his trimaran. This documentation has been translated into French and completed on navitop.fr. You should read paragraph "mecanical installation", "tuning gains" and "configuring parameters"