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Heading information tilt
Hi all
I have come accross a wierd problem with the heading information in the pypilot control / opencpn plugin.

Just a short description since it is made a little diffrent than standard:
Hardware: Raspberry Pi 2B with openplotter.
Boat. 18ton 35" steel motorboat
Controls: Hydralic valve, require 1/2 supply voltage to idle, then shift voltage,  to roughly 40 % of supply level for stb turn and 60% for ptb.  (Danfoss PVE valve)
This is done by a simple resistor network that are beeing switch via 2 relays and a op-amp in voltage follower as output amp.

Since the pypilot motor controller does not implement this way of controlling, it is set up to send out ESC signal, which is decoded by yet another arduino that tells the valve to go left or right... (hence it will not shift the rudder back to neutal, but this does not seems to be a problem)

Rudder sensor is in use.
GPS info is accuriered over usb serial from a garmin plotter 4800 baud
I have some kind of difficult getting the magnetic compass ot keep its heading, it will drift.
Ccalibration can be acchieved, but never the less it will still drift.
Sensor is MPU 9225

Starting out just to engage the AP, keeping the course seems to work fine.
However on (harder) turns, say more than 30 degrees, the course information displayed in the pypilot control or opencpn plug-in is lagging behind the acutal course.
This leads to overshooting the course desired, and it will take quite a while for the boat to get back on track, also it has on occausion lost it completely and just started to go in circles.
Also today i saw that this displayed course in the opencpn plug-in just jumped 100ish. degrees, then comming back towards the boat course.
I was under the understanding that with GPS mode selected the course should come from the GPS only, but this behaviour with the course lagging behind seems to indicate that the magnetic couse information interfers. ??
So Im kind of lost,where to begin the search for the error(s), any here which have experienced similar behaviour?
Would there be some way of taking the magnetic course information out of the equasion, since it is not desired. (but maybe required for pypilot to work?)

Happy sailing


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