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.

On Thu, Nov 15, 2018 at 8:20 AM XaviLC [email protected] 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 https://github.com/kriswiner/EM7180_SENtral_sensor_hub/issues/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.

On Fri, Nov 16, 2018 at 12:16 AM XaviLC [email protected] 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 https://github.com/kriswiner/EM7180_SENtral_sensor_hub/issues/44#issuecomment-439315509, or mute the thread https://github.com/notifications/unsubscribe-auth/AGY1ql1-ClBKbstLIgY4f_Ts5LlV3Py9ks5uvnRUgaJpZM4YgPPQ .