Calibration Questions

AxonSpark

Ok cool. Hopefully it's an easy fix. I can't wait to test out the full biped armature! 😁

daylanKifky

AxonSpark
I think I found the problem!
Or at least I found an issue with the way the accelerometer and gyro calibration data is applied. Hopefully that's the reason of your calibration problems.
I'm working on a fix, will let you know as soon as it's ready

daylanKifky

At the moment the fix is partially implemented at the branch b_bad_calib.
I should be able to complete it on the following days. If you want to test it now you might already get a better result.

this will checkout the correct branch and compile:

git pull
git checkout b_bad_calib
scons -j3 debug=1

(you will need to re-calibrate the sensor)

AxonSpark

daylanKifky I compiled the new branch and performed the calibration, but now the plugin in Blender isn't able to receive data. I seem to be connecting without a problem, but when I click the "Receive" button nothing happens.

daylanKifky

I've just pushed the complete fix. Please pull the repo and recompile, and tell me how it goes.
(you will need to re-calibrate the sensor.......... again 😁 )

If you still find problems please send me a new set of CSV's like the one you did before.

AxonSpark when I click the "Receive" button nothing happens.

Is this happening when you run the notochord with the --scan flag?
If that's the case then is normal: the current add-on is not really smart, it just assigns the rotations it receives when the label of the object matches the label of the K-Ceptor.
When using --scan the notochord assigns labels based on the position of the KC on the hierarchy, something like kc-CH_2-1 (kceptor on CHannel 2, with value 1).
The object on the testcube.blend is called Unico. In order to use it with --scan you should change it's name.

daylanKifky

While calibrating a set of sensors I realized that there's a little problem with this last fix.

If you plug the KC and proceed right away with the calibration you will probably get wrong results.

I'll solve it on the next commit. In the meantime a temporary solution is to make a dry run of the notochord in normal mode before calibrating

AxonSpark

daylanKifky Good thing I waited to calibrate! 😃Ok, so I pulled/compiled the latest version, did the notochord dry run, and then calibrated the K-Ceptor (and used the proper K-Ceptor name in the testcube file).

The results I saw are looking REALLY good! 😁When I turn and hold the K-Ceptor, I'm not seeing any of the large constant drifts that I had before. In fact, I'd say it's pretty solid, as not only does the test object stay still, but there also seems to be a significant reduction in the noise coming through as well (if it weren't for the minuscule changes in rotation values in the object panel, I wouldn't have known there was any noise at all).

The only visibly noticeable noise I saw was when the K-Ceptor was in it's resting position, but even so it doesn't seem to be that significant.

Thanks for your speedy updates!

daylanKifky

AxonSpark The results I saw are looking REALLY good! 😁When I turn and hold the K-Ceptor, I'm not seeing any of the large constant drifts that I had before.

That's great news!!
Thanks to you for the detailed feedback!, I wouldn't be able to even find this bug without the data you provided.
Let's celebrate by creating a new [Solved] tag for this forum and assigning it to this thread! 🎉🎉🎉

Once I finish solving the little issue that popped up with this modifications I'll create a new release of the notochord.
And will also update the information on the calibration section of the wiki, and add the procedure to the capturing section.

daylanKifky

I was finally able to update the information on the wiki (capturing and calibration sections). Let me know how it goes with the full body capture!

AxonSpark

daylanKifky My freelance gig started up again, so I'm going to recalibrate the remaining sensors this weekend. I've also ordered the battery pack and plan on going to the local REI to get the straps/harness I need (I figure if any one would have that sort of stuff it would be a camping supply store). Still need to order some sheets of anti-static foam.

One thing I noticed in the photos is that the K-Ceptor's are secured with screws. Do metal screws not interfere with the sensors after they've been calibrated? Or should I look into some plastic screws? Also, is it safe to use the TP holes on the Hub for screw mounting to a project box?

daylanKifky

AxonSpark Do metal screws not interfere with the sensors after they've been calibrated?

If the screws are fixed to the KC they can be made out of metal, but you will have to calibrate after you attach them together.

No to say that non-ferrous metal interfere very little with the magnetic field. Some screws contain little, or no iron.

AxonSpark

So, I calibrated the rest of my K-Ceptors, and now I seem to be getting some odd results. Some sensors calibrate ok, but others are still getting some drift when turned to 90 degrees along some axes, but not on others. I did the notochord dry run first, so I'm not sure if I did something wrong or if I should just wait for the new version to come out and calibrate again.

daylanKifky

AxonSpark
I haven't publised a new release yet because I would like to include a higher sensor read rate (as discussed here), as an experimental feature.

But I did already implement a solution for the "dry run" issue.
If you pull the b_bad_calib branch, recompile and try calibrating a sensor you will see that the notochord retries the acel and gyro part until their readings are steady.
I recalibrated all my sensors with this new version and got great results.

AxonSpark

Well, I updated the b-bad_calib branch and recompiled, but now I can't calibrate sensors. Despite the fact that the K-Ceptor is sitting still in the calibration box on a flat surface in another room, the new program keeps reading that there is too much variation, so it gets stuck endlessly retrying.

I've also tried this with the K-Ceptor outside of the calibration box and get the same result.

daylanKifky

AxonSpark
approximately how much variation are you getting?

AxonSpark

daylanKifky Here's a screen capture of the sort of result I'm getting:

And here's the dropbox link to the video file in case you need more control over playback: https://www.dropbox.com/s/hb06pqrzz6rwaws/CalibrationConstantRetryIssue01.mp4?dl=0

The numbers trend downwards, but when it gets to zero at two decimal places it's still reading as unsteady. Does it need to read zero at a full 8 decimal places before it will let me calibrate? Also, as you will see the downward trend in numbers will sometimes suddenly spike up to a higher number and then trend downward again.

daylanKifky

AxonSpark Does it need to read zero at a full 8 decimal places before it will let me calibrate?

There was some tolerance, but perhaps I made it too small. What we are measuring here is the (absolute) slope of a line fitted on the last 50 readings of the sensor. A slope close to zero indicates that even there's noise, the readings are stable and we can use that offset.

I made some cleanup and incremented the max_slope a little. Please pull and recompile.
If you still find the tolerance is too small, go ahead and modify the value on this line:

233 #define _MAX_AG_CALIB_SLOPE 0.12f

on the file src/Chordata_def.h.

(After that you should recompile)

AxonSpark

daylanKifky Hooray! The latest update worked!

This time around notochord tended to check the accelerometer between 2-5 times before moving on to the mag calibration.

I also tested all of the sensors, and it looks like they're good to go. One thing that came up during testing is that the further along I got in testing the sensors, I noticed some lag cropped up. I don't know if this was something going on with my system or a software bug. Either way, I think they're ready.

daylanKifky

AxonSpark
😁 Glad everything went right in the end!
I also normally get around 4 attempts before accepting the acel/gyro calibration.

If you keep experimenting this lag please try to identify exactly when its happening and open another thread.

Thanks again for your patience and diligence in providing precise feedback!

AxonSpark

daylanKifky I saw on Twitter that the latest notochord version was just released. Do I need to switch branches, update, and recalibrate, or should I stay on the b-bad calib branch?

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