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openai / mujoco-py

MuJoCo is a physics engine for detailed, efficient rigid body simulations with contacts. mujoco-py allows using MuJoCo from Python 3.
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Different behavior over different mujoco version. #706

Open im-Kitsch opened 2 years ago

im-Kitsch commented 2 years ago

Bug,

Hi, I am not sure if it's a feature or a bug. I validate the installation of mujoco_py from the ReadMe.md file

$ pip3 install -U 'mujoco-py<2.2,>=2.1'
$ python3
import mujoco_py
import os
mj_path = mujoco_py.utils.discover_mujoco()
xml_path = os.path.join(mj_path, 'model', 'humanoid.xml')
model = mujoco_py.load_model_from_path(xml_path)
sim = mujoco_py.MjSim(model)

print(sim.data.qpos)
# [0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]

sim.step()
print(sim.data.qpos)
# [-2.09531783e-19  2.72130735e-05  6.14480786e-22 -3.45474715e-06
#   7.42993721e-06 -1.40711141e-04 -3.04253586e-04 -2.07559344e-04
#   8.50646247e-05 -3.45474715e-06  7.42993721e-06 -1.40711141e-04
#  -3.04253586e-04 -2.07559344e-04 -8.50646247e-05  1.11317030e-04
#  -7.03465386e-05 -2.22862221e-05 -1.11317030e-04  7.03465386e-05
#  -2.22862221e-05]

To Reproduce I used the model file from mujoco200, tested on Unbuntu with Mujoco2.0 and MacOS m1pro chip with Mujoco 2.1. To reproduce, the command are as: 

import mujoco_py
import os
mj_path = mujoco_py.utils.discover_mujoco()
xml_path = os.path.join(mj_path, 'model', 'humanoid_linux_mj200.xml')
model = mujoco_py.load_model_from_path(xml_path)
sim = mujoco_py.MjSim(model)
print(sim.data.qpos)
sim.step()
print(sim.data.qpos)

Expected behavior In the website, the expected output should be 

# [0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
# [-2.09531783e-19  2.72130735e-05  6.14480786e-22 -3.45474715e-06
#   7.42993721e-06 -1.40711141e-04 -3.04253586e-04 -2.07559344e-04
#   8.50646247e-05 -3.45474715e-06  7.42993721e-06 -1.40711141e-04
#  -3.04253586e-04 -2.07559344e-04 -8.50646247e-05  1.11317030e-04
#  -7.03465386e-05 -2.22862221e-05 -1.11317030e-04  7.03465386e-05
#  -2.22862221e-05]

While on MacOS and Ubuntu is: MacOS

[0.  0.  1.4 1.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.
 0.  0.  0.  0.  0.  0.  0.  0.  0.  0. ]
[-1.02069084e-05 -2.02845751e-21  1.39975299e+00  9.99999999e-01
 -8.13718560e-21  4.26938900e-05 -8.76051246e-20 -2.50329121e-19
 -3.69825148e-05  3.17200420e-20 -2.30169113e-06  5.28067103e-05
 -6.54058085e-04 -1.64909863e-03 -1.42403772e-03  5.53515626e-05
 -2.30169113e-06  5.28067103e-05 -6.54058085e-04 -1.64909863e-03
 -1.42403772e-03 -5.53515626e-05 -5.48375278e-05  7.20916681e-05
 -1.81869652e-05  5.48375278e-05 -7.20916681e-05 -1.81869652e-05]

Ubuntu

[0.  0.  1.4 1.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.
 0.  0.  0.  0.  0.  0.  0.  0.  0.  0. ]
[-1.12164337e-05  7.29847036e-22  1.39975300e+00  9.99999999e-01
  1.80085466e-21  4.45933954e-05 -2.70143345e-20  1.30126513e-19
 -4.63561234e-05 -1.88020744e-20 -2.24492958e-06  4.79357124e-05
 -6.38208396e-04 -1.61130312e-03 -1.37554006e-03  5.54173825e-05
 -2.24492958e-06  4.79357124e-05 -6.38208396e-04 -1.61130312e-03
 -1.37554006e-03 -5.54173825e-05 -5.73572648e-05  7.63833991e-05
 -2.12765194e-05  5.73572648e-05 -7.63833991e-05 -2.12765194e-05]

Desktop (please complete the following information):

*** MacBookPro PC

*** Ubuntu PC

I think it would be much better if they have the same performance in different version. So I am not sure if it's a bug or it related to update of mujoco.

Thanks a lot for your works. Best regards.