Conversion to a quaternion rate

quaternion rate.cpp

// Given XYZ radians per second velocity.
q_from_euler(vel_quat, angVel[2] * vel_quat_dt, angVel[1] * vel_quat_dt,
             angVel[0] * vel_quat_dt);
             
// Small angle approximation from exponential map
vel_quat[Q_X] = angVel[0] * 0.5 * vel_quat_dt;
vel_quat[Q_Y] = angVel[1] * 0.5 * vel_quat_dt;
vel_quat[Q_Z] = angVel[2] * 0.5 * vel_quat_dt;
vel_quat[Q_W] = 1.0;
q_normalize(vel_quat, vel_quat);