external orientation as quaternion

Firmware/software/electronics/mechanics
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Naidala
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Posts: 8
Joined: Fri Dec 11, 2020 9:10 am

external orientation as quaternion

Post by Naidala »

Hi, I have read that in Crazyflie body frame of reference the pitch rotation is left-hand thumb rule, while the rest is right-hand.
Now, I want to send attitude measurement with Vicon MoCap, which gives rotation, as far as I understood, in a standard counter-clockwise fashion.
Vicon can return me the quaternion of the global rotation, and I suppose I may just have to change some component's sign.
Has anyone else already tried to use Vicon and may give some advice?
whoenig
Expert
Posts: 377
Joined: Mon Oct 27, 2014 2:55 am

Re: external orientation as quaternion

Post by whoenig »

This strange signage is only true for the euler angle logging variables (stateEstimate.{roll,pitch,yaw}) and it is there for historical reasons and was not changed to keep backwards compatibility. The on-board quaternion follows the regular right-handed rule, which is also used by VICON. Thus, you can directly use the information that you get from the DataStream SDK, provided that you created the rigid body in Vicon Tracker such that positive x is where the radio chip antenna is.
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