Nav mode route following

[joshuajayg]

I have installed my pypilot and it has worked quite well under sail after messing around with some slew rates.  What I can't figure out though is why I'm having trouble following a route in OpenCPN.  I've attached a screenshot of my route (blue line) and track (yellow line.)  When arriving at a point, the autopilot will make the turn early, turn beyond the new course, and very slowly re-intercept the course.  In this channel I have to disengage the autopilot in order to keep from running aground or hitting a buoy.  What setting am I missing in this situation?

My setup:
-Pypilot running on its own Pi Zero W with IMU.
-OpenCPN and Signal K running on separate Pi 5.
-Common network between computers, OpenCPN is sending RMB, RMC, APB, RTE, and XTE to Signal K over UDP.  
  Signal K is sending APB, WMV (true and apparent), RMC, VHW, VWR, VWT, and XTE (rhumb line) over TCP to the pypilot.
-Autopilot Provider and Course Data Provider plugins are both enabled. 
-Vessel is a 40' Valiant 40 with an electric ram driving the steering quadrant.  The ram is from the Alpha 3000 autopilot that was previously installed (works great.)

This oversteering in nav mode happens both under sail and motoring thought the shown photos is while under sail.

Joshua
   

[seandepagnier]

Did you try the autopilot route plugin?

The basic route following logic in opencpn is derived from airplane runway approaches (cross track error) and makes abrupt changes at waypoints. It doesnt work well if the route changes by more than 10-15 degrees between way points.


The autopilot route plugin performs a more continuous correction always aiming at a point some distance ahead along the route and has more parameters to adjust as well.

[joshuajayg]

I actually fly airplanes for a living, occasionally when my autopilot drives harder than expected at a new or unexpected course, I refer to it as a honey badger. Haha.

I have not tried the autopilot route plugin. I have it downloaded but didn't try enabling it. I will give it a try when I'm back at the boat in a month.

Thank you.

[seandepagnier]

yes be sure to tweak the parameters for distance and max error.  Maybe make the max error a bit more permissive 35 degrees, and then tighten the distance as you can for the conditions to set the turn radius at each waypoint.  Finally the FF gain in pypilot will somewhat determine under/over shoot, but it is much better than you are experiencing.

Near sounding 26 the track was farther from the route (14 meter) because I lost the wind (sail luffing) normally it stays under 5 meters error.

[ironman]

I can certainly vouch for the Autopilot Route plugin and the accuracy. The default settings of that plugin (Route Position Bearing, By Distance, 100m, 30 degrees) are a good starting point. Indeed, when the other gains are already tuned to satisfaction, the FF gain is additionally important for route following of any kind.

For more background information, check https://github.com/pypilot/workbook/wiki...ute-Plugin