Problem met using "gym.acquire_jacobian_tensor"

I’m trying to repeat the example on another arm unitree-z1, but the jacobian i get using “gym.acquire_jacobian_tensor” is very strange. It’s shape is (num_env, 7 ,6, 12). However, it’s supposed to be (num_env, num_link, 6, num_dof) and the num_dof of unitree-z1 is 6. So, I’m really confused since i also don’t understand how Isaac Gym acquire this jacobian.

Does anyone meet similar problems before or understand why this happpen.

The urdf link of the arm unitree-z1 is:

Best Regards

Solved. Because I didn’t fix the base of the robot