Thanks for your answer. I guess I should have mentioned that I don't have the openplotter-integrated pypilot, but the TinyPilot connected to the OpenCPN plugin. So the IMU does not sit on the Raspberry that runs OpenPlotter, it sits on the Raspberry that runs Tinypilot. The openplotter does not show the presence of the TinyPilot IMU, and the openplotter calibration facilities don't apply to the remote TinyPilot. I guess that's how this is designed. At the risk of stating something obvious to others, allow me to summarize what I understand now so it can be validated and may be informative to others.
The TinyPilot web client has three user interfaces. At first, the LCD+keyboard, but I don't have that installed. Second there is a web client, that you get when you point your browser to the TinyPilot's ip address. This web client has only one calibration facility, but only for the inertial sensors. It shows a progress bar, apparently the equivalent of the 3d sailboat picture. Third, there is an OpenCPN plugin that is already available in the OpenCPN of openplotter. It only needs to be enabled, and then you have this extra button in OpenCPN that reveals another PyPilot interface, but quite a comprehensive one.
But when I got it all hooked up, I still could not find a button to start the compass calibration facility in this plugin, only a tab that shows some calibration parameters and a checkbox to lock it. I had already suspected that there was some automatic, ongoing compass calibration: just start sailing and it calibrates itself, I had heard in one of the videos. Too bad because I really liked the orbital dots interface (just as a brain stimulator I guess :-) ). However it was consistent with the need to lock the calibration, so that tab made sense. Also, running the system on my workbench I had already noted that the compass reading was originally somewhat changeable, and I had attributed that to some automated calibration going on. I had not gotten to walking my pypilot in full circles though the workshop to finish this calibration; there are limits to my enthousiasm and on the boat that's far easier.
But there I found the heading difference and hence came my question.
Your heading offset put me on the track to check the various sources of information again and I think I found it now. Sean mentions in the TinyPilot video 'Once [the inertial sensors are] leveled, automatic compass calibration can work better. It can be aligned to magnetic North by entering a degree offset. This ensures accurate headings and heel angles are reported". So there is automatic compass calibration and it does require a degree offset. And I just found that by changing imu.heading_offset this has a direct effect on the actual heading reported in the plugin.
So this answers my question on how to fix the offset. It leaves the question open whether or not there is some automatic process that sets the offset based on GPS COG. And it may be a pointer to you to the facility to lock your calibration.
Thx,
-
![[Image: attachment.php?aid=498]](http://forum.openmarine.net/attachment.php?aid=498)
The TinyPilot web client has three user interfaces. At first, the LCD+keyboard, but I don't have that installed. Second there is a web client, that you get when you point your browser to the TinyPilot's ip address. This web client has only one calibration facility, but only for the inertial sensors. It shows a progress bar, apparently the equivalent of the 3d sailboat picture. Third, there is an OpenCPN plugin that is already available in the OpenCPN of openplotter. It only needs to be enabled, and then you have this extra button in OpenCPN that reveals another PyPilot interface, but quite a comprehensive one.
But when I got it all hooked up, I still could not find a button to start the compass calibration facility in this plugin, only a tab that shows some calibration parameters and a checkbox to lock it. I had already suspected that there was some automatic, ongoing compass calibration: just start sailing and it calibrates itself, I had heard in one of the videos. Too bad because I really liked the orbital dots interface (just as a brain stimulator I guess :-) ). However it was consistent with the need to lock the calibration, so that tab made sense. Also, running the system on my workbench I had already noted that the compass reading was originally somewhat changeable, and I had attributed that to some automated calibration going on. I had not gotten to walking my pypilot in full circles though the workshop to finish this calibration; there are limits to my enthousiasm and on the boat that's far easier.
But there I found the heading difference and hence came my question.
Your heading offset put me on the track to check the various sources of information again and I think I found it now. Sean mentions in the TinyPilot video 'Once [the inertial sensors are] leveled, automatic compass calibration can work better. It can be aligned to magnetic North by entering a degree offset. This ensures accurate headings and heel angles are reported". So there is automatic compass calibration and it does require a degree offset. And I just found that by changing imu.heading_offset this has a direct effect on the actual heading reported in the plugin.
So this answers my question on how to fix the offset. It leaves the question open whether or not there is some automatic process that sets the offset based on GPS COG. And it may be a pointer to you to the facility to lock your calibration.
Thx,
-