How are you gettting the hardware quaternions?

[XaviLC]

Hello @kriswiner ,

I am newbie on the rotation topic using quaternions, I have been reading abot then and the different ways of representing rotation changes, so sorry in advance if my questions might be quite simple.

I have been looking your code for the BMI160, device that I am using, and there is a point where obtaining the quaternions that I get a bit lost.

I see that you have defined to set of quaternions, hardware quaternions Quat[4] and software quaternions q[4]. Could you explain me how you are obtaining the hardware quaternions? I am especially interested in q0 (Quat[0]), is this value given only by EM7180 sensor or it can be retreived as well from BMI160?

And finally the software quaternions q[4] are coming from the application of the MadgwickQuaternionUpdate() method?

Thanks in advance!

[kriswiner]

Yes, hardware qs from the EM7180 and software qs from the madgwick filter.

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On Thu, Nov 15, 2018 at 8:20 AM XaviLC ***@***.***> wrote: Hello @kriswiner <https://github.com/kriswiner> , I am newbie on the rotation topic using quaternions, I have been reading abot then and the different ways of representing rotation changes, so sorry in advance if my questions might be quite simple. I have been looking your code <https://github.com/kriswiner/EM7180_SENtral_sensor_hub/blob/master/EM7180_BMI160_AK8963C.ino> for the BMI160, device that I am using, and there is a point where obtaining the quaternions that I get a bit lost. I see that you have defined to set of quaternions, hardware quaternions Quat[4] and software quaternions q[4]. Could you explain me how you are obtaining the hardware quaternions? I am especially interested in q0 ( Quat[0]), is this value given only by EM7180 sensor or it can be retreived as well from BMI160? And finally the software quaternions q[4] are coming from the application of the MadgwickQuaternionUpdate() method? Thanks in advance! — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#44>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AGY1qkwxQSJYytvlfK4hThXHQHdkFxSBks5uvZQygaJpZM4YgPPQ> .

[XaviLC]

Thanks for replying,

Then that means that BMI160 doesn't provide the value q0 from hardware and if I use this sensor I would have to make use of just the software base right?
One more question regarding to q0, I have seen other repo of yours for the MPU9250, this sensor also provides the q0 as far as I understood from your code, but I could not find any explicit register in the register map of the MPU9250 that holds q0. Could you kindly point me out where or what I should look to find that register?

Thank you very much,

REgards!

[kriswiner]

Tne BNO055 is what you want if you want to get 9 DoF quaternions from one device. But it is not as accurate as some other solutions. The MPU9250 can provide 6 DoF quaternions but doesn't use the magnetometer data in the orientation solution. Using it's DMP is not easy. This <https://www.tindie.com/products/onehorse/ultimate-sensor-fusion-solution-mpu9250/> the most accurate quaternion engine you can buy at this size and price range.

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On Fri, Nov 16, 2018 at 12:16 AM XaviLC ***@***.***> wrote: Thanks for replying, Then that means that BMI160 doesn't provide the value q0 from hardware and if I use this sensor I would have to make use of just the software base right? One more question regarding to q0, I have seen other repo of yours for the MPU9250, this sensor also provides the q0 as far as I understood from your code, but I could not find any explicit register in the register map of the MPU9250 that holds q0. Could you kindly point me out where or what I should look to find that register? Thank you very much, REgards! — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#44 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AGY1ql1-ClBKbstLIgY4f_Ts5LlV3Py9ks5uvnRUgaJpZM4YgPPQ> .