[Question] Issue With Custom Cube Lifting Task Using UR10e and Robotiq 2F-140

[hieuapg]

Hello, I'm working on a custom lift task in Isaac Lab using the UR10e robotic arm equipped with the Robotiq 2F-140 gripper. Below, I summarize the issue I’m currently encountering.

Robot Configuration
I created a custom ArticulationCfg for the UR10e with the Robotiq 2F-140:
`
import isaaclab.sim as sim_utils
from isaaclab.actuators import ImplicitActuatorCfg
from isaaclab.assets.articulation import ArticulationCfg

UR10e_ROBOTIQ_CFG = ArticulationCfg(
spawn=sim_utils.UsdFileCfg(
usd_path=f"/home/hieuapg/Desktop/IsaacLab/source/isaaclab_assets/isaaclab_assets/robots/ur10e_robotiq.usd",
rigid_props=sim_utils.RigidBodyPropertiesCfg(
disable_gravity=False,
max_depenetration_velocity=5.0,
),
activate_contact_sensors=False,
),
init_state=ArticulationCfg.InitialStateCfg(
joint_pos={
# Arm joints
"shoulder_pan_joint": 0.0,
"shoulder_lift_joint": -1.0,
"elbow_joint": 1.0,
"wrist_1_joint": 0.0,
"wrist_2_joint": 0.0,
"wrist_3_joint": 0.0,
# Gripper joints (optional initial positions)
"left_inner_finger_joint": 0.0,
"right_inner_finger_joint": 0.0,
"left_outer_finger_joint": 0.0,
"right_outer_finger_joint": 0.0,
"finger_joint": 0.0,
"right_outer_knuckle_joint": 0.0,
"right_inner_finger_pad_joint": 0.0,
"left_inner_finger_pad_joint": 0.0
},

),
actuators={
    "arm": ImplicitActuatorCfg(
        joint_names_expr=[
            "shoulder_pan_joint",
            "shoulder_lift_joint",
            "elbow_joint",
            "wrist_1_joint",
            "wrist_2_joint",
            "wrist_3_joint",
        ],
        velocity_limit_sim=20.0,
        effort_limit_sim=87.0,
        stiffness=800.0,
        damping=40.0,
    ),
    "gripper": ImplicitActuatorCfg(
        joint_names_expr=[
            "left_inner_finger_joint",
            "right_inner_finger_joint",
            "left_outer_finger_joint",
            "right_outer_finger_joint",
            "finger_joint",
            "right_outer_knuckle_joint",
            "right_inner_finger_pad_joint",
            "left_inner_finger_pad_joint"
        ],
        velocity_limit_sim=20.0,
        effort_limit_sim=20.0,
        stiffness=500.0,
        damping=0.0,
    ),
},

)

"""Configuration of UR10e arm with Robotiq 2F-140 gripper using implicit actuator models."""
`

Lift environment configuration

`# Copyright (c) 2022-2026, The Isaac Lab Project Developers

All rights reserved.

SPDX-License-Identifier: BSD-3-Clause

from isaaclab.assets import RigidObjectCfg
from isaaclab.sensors import FrameTransformerCfg
from isaaclab.sensors.frame_transformer.frame_transformer_cfg import OffsetCfg
from isaaclab.sim.schemas.schemas_cfg import RigidBodyPropertiesCfg
from isaaclab.sim.spawners.from_files.from_files_cfg import UsdFileCfg
from isaaclab.utils import configclass
from isaaclab.utils.assets import ISAAC_NUCLEUS_DIR

from isaaclab_tasks.manager_based.manipulation.lift import mdp
from isaaclab_tasks.manager_based.manipulation.lift.lift_env_cfg import LiftEnvCfg

Your robot config (UR5 + Robotiq 2F)

from isaaclab_assets.robots.ur10e_robotiq import UR10e_ROBOTIQ_CFG
from isaaclab.markers.config import FRAME_MARKER_CFG # isort: skip

@configclass
class UR10eRobotiqCubeLiftEnvCfg(LiftEnvCfg):
def post_init(self):
super().post_init()

    # Use your UR5+Robotiq asset
    self.scene.robot = UR10e_ROBOTIQ_CFG.replace(prim_path="{ENV_REGEX_NS}/ur10e")

    self.actions.arm_action = mdp.JointPositionActionCfg(
        asset_name="robot",
        # use regex so it matches whether joints are ROS-style or numbered
        joint_names=["shoulder_pan_joint", "shoulder_lift_joint", "elbow_joint", "wrist_1_joint", "wrist_2_joint", "wrist_3_joint"],
        scale=0.5,
        use_default_offset=True,
    )

    self.actions.gripper_action = mdp.BinaryJointPositionActionCfg(
        asset_name="robot",
        joint_names=["gripper"],
        open_command_expr={"gripper": 0.8},   # tune if needed
        close_command_expr={"gripper": 0.0},
    )

    self.commands.object_pose.body_name = "robotiq_base_link"

    # -------------------------
    # Object (cube)
    # -------------------------
    self.scene.object = RigidObjectCfg(
        prim_path="{ENV_REGEX_NS}/Object",
        init_state=RigidObjectCfg.InitialStateCfg(pos=[0.5, 0, 0.055], rot=[1, 0, 0, 0]),
        spawn=UsdFileCfg(
            usd_path=f"{ISAAC_NUCLEUS_DIR}/Props/Blocks/DexCube/dex_cube_instanceable.usd",
            scale=(0.8, 0.8, 0.8),
            rigid_props=RigidBodyPropertiesCfg(
                solver_position_iteration_count=16,
                solver_velocity_iteration_count=1,
                max_angular_velocity=1000.0,
                max_linear_velocity=1000.0,
                max_depenetration_velocity=5.0,
                disable_gravity=False,
            ),
        ),
    )

            # Listens to the required transforms (UR5 version)
    marker_cfg = FRAME_MARKER_CFG.copy()
    marker_cfg.markers["frame"].scale = (0.1, 0.1, 0.1)
    marker_cfg.prim_path = "/Visuals/FrameTransformer"
    self.scene.ee_frame = FrameTransformerCfg(
        prim_path="{ENV_REGEX_NS}/ur10e/base_link",
        debug_vis=True,
        visualizer_cfg=marker_cfg,
        target_frames=[
            FrameTransformerCfg.FrameCfg(
                prim_path="{ENV_REGEX_NS}/ur10e/ee_link/robotiq_base_link",
                name="end_effector",
                offset=OffsetCfg(
                    pos=[0.0, 0.0, 0.1034],
                ),
            ),
        ],
    )

`

Current Issue:

I adapted the default Franka Lift task from Isaac Lab to work with the UR10e + Robotiq 2F-140 setup by modifying the robot and environment configurations as shown above.

However, when I run the command:
python scripts/reinforcement_learning/skrl/train.py --task=Isaac-Lift-Cube-ur10e-Robotiq-v0

The following error appears:

`Traceback (most recent call last):
File "/home/hieuapg/Desktop/IsaacLab/source/isaaclab/isaaclab/sensors/sensor_base.py", line 159, in
lambda event, obj=weakref.proxy(self): obj._debug_vis_callback(event)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/hieuapg/Desktop/IsaacLab/source/isaaclab/isaaclab/sensors/frame_transformer/frame_transformer.py", line 449, in _debug_vis_callback
frames_pos = torch.cat([self._data.source_pos_w, self._data.target_pos_w.view(-1, 3)], dim=0)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'view'
[INFO]: Time taken for simulation start : 38.531995 seconds
Error executing job with overrides: []
Traceback (most recent call last):
File "/home/hieuapg/Desktop/IsaacLab/source/isaaclab_tasks/isaaclab_tasks/utils/hydra.py", line 100, in hydra_main
func(env_cfg, agent_cfg, args, **kwargs)
File "/home/hieuapg/Desktop/IsaacLab/scripts/reinforcement_learning/skrl/train.py", line 201, in main
env = gym.make(args_cli.task, cfg=env_cfg, render_mode="rgb_array" if args_cli.video else None)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/hieuapg/miniconda3/envs/env_isaaclab/lib/python3.11/site-packages/gymnasium/envs/registration.py", line 734, in make
env = env_creator(**env_spec_kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/hieuapg/Desktop/IsaacLab/source/isaaclab/isaaclab/envs/manager_based_rl_env.py", line 80, in init
super().init(cfg=cfg)
File "/home/hieuapg/Desktop/IsaacLab/source/isaaclab/isaaclab/envs/manager_based_env.py", line 173, in init
self.sim.reset()
File "/home/hieuapg/Desktop/IsaacLab/source/isaaclab/isaaclab/sim/simulation_context.py", line 530, in reset
self.render()
File "/home/hieuapg/Desktop/IsaacLab/source/isaaclab/isaaclab/sim/simulation_context.py", line 601, in render
raise exception_to_raise
File "/home/hieuapg/Desktop/IsaacLab/source/isaaclab/isaaclab/sensors/sensor_base.py", line 303, in _initialize_callback
self._initialize_impl()
File "/home/hieuapg/Desktop/IsaacLab/source/isaaclab/isaaclab/sensors/frame_transformer/frame_transformer.py", line 192, in initialize_impl
raise ValueError(
ValueError: Failed to create frame transformer for frame 'None' with path '/World/envs/env./ur10e/base_link'. No matching prims were found.

Set the environment variable HYDRA_FULL_ERROR=1 for a complete stack trace.`

I don't know how to fix this error. Any help would be appreciated. Thank you so much.