Implement floor inclination and various properties

[lorycontixd]

No description provided.

[lorycontixd]

Implementation doubts for the future:

• mujocoSimulator.load_model is functional when loading a single model, and a floor inclination is passed each time. In case of multiple models, either convert the function to load_models or separate floor definition from model definition.

[lorycontixd]

⚠️ The robotModel class does not work well with temporary files, even if the file still exists on the machine.
It's good practise then to pass a path to a physical file.

The issue is most likely raised from this line in Adam when used on a temporary file.

[lorycontixd]

@CarlottaSartore Adding you as a reviewer for starting the merging process.

[lorycontixd]

Current usage of floor definition:

mujoco_instance = MujocoSimulator()
mujoco_instance.load_model(
    robot_model_init,
    s=[-0.55, 0],
    xyz_rpy=np.asarray([0, 0, initial_height, 0.5, 0, 0]),
    floor_opts={
        "friction" : 0.5,
        "inclination_deg" : [0., 10., 0.]
    },
)

Currently accepted floor_opts keys are:

• friction: friction coefficient of the floor ($0 \lt \mu \lt 1$) (default: 0.6)
• inclination: euler angles for the inclination of the plane (in degrees) (default: [0, 0, 0])

If an invalid key is passed, an exception is raised.
If a key is not passed, default values are used.

[lorycontixd]

Current usage of floor definition:

mujoco_instance = MujocoSimulator()
mujoco_instance.load_model(
    robot_model_init,
    s=[-0.55, 0],
    xyz_rpy=np.asarray([0, 0, initial_height, 0.5, 0, 0]),
    floor_opts={
        "friction" : 0.5,
        "inclination_deg" : [0., 10., 0.]
    },
)

Currently accepted floor_opts keys are:

* friction: friction coefficient of the floor (
    0
    <
    μ
    <
    1
  ) (default: 0.6)

* inclination: euler angles for the inclination of the plane (in degrees) (default: [0, 0, 0])

If an invalid key is passed, an exception is raised. If a key is not passed, default values are used.

---

ℹ️ Now separated into mujoco's 3 different types of contact frictions:

mujoco_instance = MujocoSimulator()
    mujoco_instance.load_model(
        robot_model,
        s=[-0.55, 0],
        xyz_rpy=np.asarray([0, 0, initial_height, 0.5, 0, 0]),
        floor_opts={
            "sliding_friction" : 1.,
            "torsional_friction" : 0.01,
            "rolling_friction" : 0.0001,
            "inclination_deg" : [0, 10.0, 0]
        },
    )