The acquired initial yaw from the robot pose and IMU information is 180°.

[Wan020607]

I want to ask why the yaw axis of the robot's IMU pose is 180° in the initial state. I suspect that there is an issue with the publishing order of the "/imu" topic. So, in humanoid_sim, I changed the assignment from:

bodyImu.orientation.x = ori[1];
bodyImu.orientation.y = ori[2];
bodyImu.orientation.z = ori[3];
bodyImu.orientation.w = ori[0];

to:

bodyImu.orientation.x = ori[0];
bodyImu.orientation.y = ori[1];
bodyImu.orientation.z = ori[2];
bodyImu.orientation.w = ori[3];

After this change, the IMU topic displayed the correct robot pose, but the robot immediately fell over. How should I solve this issue?