[Bug Report] actuation_pd.py DCMotorCfg saturation allow a dictionary

[Robokan]

If you are submitting a bug report, please fill in the following details and use the tag [bug].

Describe the bug

in the class DCMotorCfg in actuation_pd.py line 182

if self.cfg.saturation_effort is not None: self._saturation_effort = self.cfg.saturation_effort else: self._saturation_effort = torch.inf

should be:

    self._saturation_effort = self._parse_joint_parameter(self.cfg.saturation_effort, torch.inf)

A clear and concise description of what the bug is.

It crashed when using different saturations for different actuators.

Steps to reproduce

If the Go1 actuator is specified according to the spec sheet:

GO1_ACTUATOR_CFG = ActuatorNetMLPCfg( joint_names_expr=["._hip_joint", "._thigh_joint", "._calf_joint"], network_file=f"{ISAACLAB_NUCLEUS_DIR}/ActuatorNets/Unitree/unitree_go1.pt", pos_scale=-1.0, vel_scale=1.0, torque_scale=1.0, input_order="pos_vel", input_idx=[0, 1, 2], effort_limit={"._hip_joint": 23.7, "._thigh_joint": 23.7, "._calf_joint": 35.5}, # taken from spec sheet velocity_limit=30.0, # taken from spec sheet saturation_effort={"._hip_joint": 23.7, "._thigh_joint": 23.7, ".*_calf_joint": 35.5} # same as effort limit

It will crash complaining that dictionaries are not supported

Please try to provide a minimal example to reproduce the bug. Error messages and stack traces are also helpful.

System Info

Describe the characteristic of your environment:

• Commit: [e.g. 8f3b9ca]
• Isaac Sim Version: [e.g. 2022.2.0, this can be obtained by cat ${ISAACSIM_PATH}/VERSION] 4.0
• OS: [e.g. Ubuntu 20.04]
• Ubuntu 20.04
• GPU: [e.g. RTX 2060 Super]
• RTX 4090
• CUDA: [e.g. 11.4]
• GPU Driver: [e.g. 470.82.01, this can be seen by using nvidia-smi command.]

Additional context

Add any other context about the problem here.

Checklist

• [x] I have checked that there is no similar issue in the repo (required)
• [x] I have checked that the issue is not in running Isaac Sim itself and is related to the repo

Acceptance Criteria

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• [ ] Criteria 1
• [ ] Criteria 2

[Mayankm96]

Although not a deal breaker for us to implement this functionality, is this something that conceptually makes sense?

To me, an actuator is a physical drive, and the limits are specific to that drive. If the robot has different drives, there should be different actuator models for them, which should be grouped into the actuators dictionary.

[Robokan]

In the case of the Go1 and Go2 they have the same actuators at each joint but at the knees they add a reduction gear. This effects the the torque and max speed of those actuators. I agree with your question. What is the best way to handle this. Should the knees have different actuator models in this case? Or just a way to make the adjustment on the actuator config itself?