A small problem in coordinate

[KUsaka-xu]

First, thanks for opensource. In the original StateRL.cpp code, the conversion of ang_vel and gravity_vec to local coordinates is correct, but it does not seem to be applicable to the isaacsim framework. When running in the isaacsim framework, sim2sim will have the body twitching and falling after turning 90 degrees. For the isaacsim framework, the description of ang_vel and gravity_vec seems to be in the body coordinate system.

[legubiao]

I built StateRL.cpp from rl_sar project and actually I didn't fully figure out it before. I just solved this problem in my latest commit.

1. About coordinate system: ang_vel should under body frame. rl_sar has the conversion because the IMU in Gazebo Classic is under world system, but in Gazebo Harmonic and Mujoco IMU is under body frame. So I just remove the conversion for ang_vel. The conversion for gravity_vec should be kept as I tested.
2. About leg sequence: In legged_gym, the sequence is FL FR RL RR and in isaac lab the sequence is FR FL RR RL. This is the main reason to have the body twitching and falling after turning 90 degrees.

You can launch go2 gazebo for the isaac sim policy.