Pypilot with ST4000 autohelm

[Peter—]

opencpn can produce and output APB and can relay any others

I have proven some time ago that the "standard" route following using cross track error is sub-optimal especially for sailing.   It works but it's clearly based on what they use on aircraft where this logic was first devised so it works also on powerboats without as terrible results, but in all cases it is a bad way to follow a route.

The intention is also to go from waypoint to waypoint which is not really the same as following a route, so with cross track error logic, it can often steer the wrong correction based on cross track error near a waypoint where you will then immediately turn back the other way resulting in oversteering.   the route position bearing mode in the autopilot route plugin of opencpn offers a mode where the autopilot always steers a course toward a position somewhere ahead of the boat  along the route so there are no discontinuities at each waypoint, and it would in this case make the correct change, or no change at all in the above case without possibly "correcting" in a way that will result in oversteering just before a waypoint.

So as far as I'm concerned cross track error is dead and exists still because of stubborn people like the same ones who use the windows operating system or many other things that just make life more difficult and less efficient

Hi Sean

Thanks for the information. I can understand where you are coming from, and if I had the time I would also program my own motor controller and make a much better solution. 

But as of right now, I’m planning to buy a much bigger boat in a couple of years and that will then be the one that I’ll do much more serious project on. 

Until then, I have to thank you for the Pypilot software it’s a great tool and I’m happy that I don’t need to program my own PID controller for now. That being said, maybe one day if it get the time I would try to implement an adaptive PID controller that would allow for nearly perfect control for everyone out there and no one would need to worry about their gains etc..

Thanks for the advice on the cross track error

Br, Peter