I am working with MPU9250 and I have implemented attitude & heading reference system based on Madgwick/Mahony filter. I capture the raw data [accel, gyro, mag] and pass to the Madgwick filter in order to get the quaternion. The attitude data [roll, pitch and yaw] is then obtained from these quaternions using below equations.
roll = atan2(2*(q0*q1+q2*q3), 1-2*(q1*q1+q2*q2)) * 180.0/M_PI; pitch = asin(2*(q0*q2-q3*q1)) * 180.0/M_PI; yaw = atan2(2*(q0*q3+q1*q2), 1-2*(q2*q2+q3*q3)) * 180.0/M_PI;
My question is in which frame [Earth centered earth fixed, Earth centered inertial frame, local/body frame or any other frame] the orientation data is represented?