2022-09-22, 08:36 AM
Thanks for the response Sean.
I hadn't done the accelerometer calibration as per wiki. I was aware of it but confused about its necessity. Obviously I didn't read it properly.
Carried out the procedure as per wiki today which seemed to work. Noted that there were only small changes to the imu.alignmentQ values in the .conf file. Is that where I should be looking? I have attached the calibration plot, is that how it should appear once successful? Might be a little while before I can redo the compass calibration.
Regarding the heading on our last trip, yes, we did have only about 100 deg reading change for a 180 deg course change. Attached photo of OpenCPN showing boat heading error. Course about 003 deg, mode north up. Heading error was constant. I don't have a good photo of the return trip heading. Heading was correct at 90 deg. At the time of the photo the boat was running in track mode on the old Raymarine pilot under OpenCPN control. On the return trip at 180 deg approx, I ran on pypilot gps mode and then the O heading was alternating between the pypilot compass reading of about 135 deg and the correct heading from either the old fluxgate sensor or COG. I do have video but file size too large.
I can see there is an inherent error in the magnetometer reading of a deg or two which is really less than 1% which is not bad for any sensor and would be ok to hold a course regardless of the reading but it would be nice to get a more accurate number.
I hadn't done the accelerometer calibration as per wiki. I was aware of it but confused about its necessity. Obviously I didn't read it properly.
Carried out the procedure as per wiki today which seemed to work. Noted that there were only small changes to the imu.alignmentQ values in the .conf file. Is that where I should be looking? I have attached the calibration plot, is that how it should appear once successful? Might be a little while before I can redo the compass calibration.
Regarding the heading on our last trip, yes, we did have only about 100 deg reading change for a 180 deg course change. Attached photo of OpenCPN showing boat heading error. Course about 003 deg, mode north up. Heading error was constant. I don't have a good photo of the return trip heading. Heading was correct at 90 deg. At the time of the photo the boat was running in track mode on the old Raymarine pilot under OpenCPN control. On the return trip at 180 deg approx, I ran on pypilot gps mode and then the O heading was alternating between the pypilot compass reading of about 135 deg and the correct heading from either the old fluxgate sensor or COG. I do have video but file size too large.
I can see there is an inherent error in the magnetometer reading of a deg or two which is really less than 1% which is not bad for any sensor and would be ok to hold a course regardless of the reading but it would be nice to get a more accurate number.