How to use cal data from MagCal/Magneto into AHRS

Hi Kevin C, yes l now see what you say about Z, I have done nothing different in the following apart from l have gone out to my front yard again, closest thing metallic >10M apart from laptop at >3M and mega at<1M. l have attached old b IMU, done out in the open. 1 is done moving in the open air where calibrated, the other is on the ALL wooden compass rose. Z are in spec, still way of centre though.
Could you please also answer questions asked previously.
Regards
Kevin

[quote=“kevin1961”]Hello again Kevin, could you please say what you believe is the best results the V3 will do.
Linearity, how accurate around the full 360 degrees.
Magnetic North, how accurate to Mag North, (±variation)
Repeatability, how close will it be of the previous reading, after power ON/Off a few times.
Roll/Tilt, how much should the compass heading change over a horizontal reading to say 30 degree tilt left/right.
All of the above are an issue with the V3 and me.[/quote]
old b, outside in air.xlsx (45.2 KB)
old b, outside on compass rose, by trees front yard.xlsx (194 KB)

Hi All, compass heading done on ALL wooden Compass Rose, Mag N approx by yacht hand held compass. Done as per previous post in front yard. Between +12, -9 to compass headings.
Regards
Kevin
old b, COMPASS HEADING ,outside on compass rose, by trees front yard, .xlsx (9.67 KB)

Hi, Kevin.

It looks like your two most recent plots are better centered around the origin, though I can see that they are still not quite circular. The raw values and your calibration constants seem reasonable to me.

We have not characterized the properties (linearity, heading accuracy, etc.) that you asked about previously. Our MinIMU and other similar boards are primarily intended to be carrier boards to make the sensor chips easier to interface with, and we make an example AHRS program available in the hopes that users will find it helpful as a starting point, but it might be that you are looking for better performance than the software or the sensors themselves can provide. You might get better results with a different calibration method or AHRS implementation (some of which Jim has touched on, and some examples can be found on the Resources tab of the product page), but we don’t have any specific recommendations about those.

- Kevin C

Hi Kevin C, l have re down loaded RTIMUlib and now it has compiled l was able to do another set of data.
This was done outside, calibrated using ArdunioMagCal and saved to eprom. Compass readings done as others with mag N via yacht hand held compass an nearest metal >4M away.
-7 to +10 error which is slightly better than previous.
I have also included (something you would be aware, but don’t really won’t shown l imagine) your competitors BNO55.
I was hoping you would have been able to some how correct the large errors from the V3 (l now you don’t make the chips), as you can see the BNO55 are near perfect including tilting 30 degrees left and right.
Thank you for your time, even if the reply’s were very slow in coming.(were as Jim’s (thanks Jim)were very quick and helpful).
Regards
Kevin D
Kevins_ BNO055 and IMUV3.xlsx (14.4 KB)

The comparison with the BNO055 is interesting; thanks for sharing it. Given the difference in price, I wouldn’t be too surprised if it is inherently a better-performing part than the sensors on the MinIMU, and if you like the results you are getting from it, great.

We would like to look at providing better software for our IMUs, and it would be nice for it to eventually have an easier and more accurate calibration process, but it is not something we are currently focusing on.

- Kevin C

Hi Kevin C, I appreciate your honesty about other IMU’s. Re pricing there is no difference down here, at about $55 Aust each and l ended up buying 4 xV3. One thing that l hadn’t done which could make a difference is to do the RTEllipsoidFit but l see this is in Lib 2, and l could not get it to compile (know l now why this lib compiled as it was for Ardunio, but it doesn’t have RTEllipsoidFit) and l didn’t do the Accl cal thingy as l don’t understand it. If you get the time you could use both and show that your results are much improved and that l have been unfair in my comparison, please do.
Regards
Kevin D