Quadruped robot examples are not working well in IsaacSim 2023.1.1

I would like to move from IsaacSim 2022.2.1 to IsaacSim 2023.1.1.
However, the robot doesn’t move the same as in 2022.2.1.

As you can see in the gif files below, the robot cannot balance well.

  1. AnymalC (standalone_examples/api/omni.isaac.quadruped/anymal_standalone.py)
    At 2022.2.1, it could balance well, but it almost falls down in 2023.1.1.

  2. A1 (standalone_examples/api/omni.isaac.quadruped/a1_standalone.py)
    This is an MPC controller, and A1 is very unstable. However, this controller worked well in 2022.2.1.

So, I am wondering about these situations:

  1. Are there some physics changes?
  2. If the physics has changed, when I trained an agent from IsaacGym Preview 4, does it not fit IsaacSim 2023.1.1?
  3. If the physics has not changed, why don’t the controllers work in the 2023.1.1 version? And how do I have to modify the code to make it the same as in the 2022.2.1 version?

Is there anyone who can assist with this problem?

When I changed the physics_dt, it worked. However, I don’t know why it is working.

I also have a same problem, but I could not find proper physics_dt. What value did you used?

I used physics_dt = 1 / 800.0

Hope this helps you.

Thanks. from my testing, it seems that the problem is from raycast height detection(I tested with other robot and policy, with no raycast use) but not tried to fixed it yet.

Lets hope this kind of problem is fixed in isaac lab, will be release in end of the May