DexForce · yuecideng · Jun 25, 2026 · Jun 25, 2026 · Jun 25, 2026 · Jun 25, 2026
diff --git a/configs/agents/rl/push_cube/gym_config.json b/configs/agents/rl/push_cube/gym_config.json
@@ -122,13 +122,10 @@
         }
     },
     "robot": {
+        "robot_type": "URRobot",
         "uid": "Manipulator",
         "urdf_cfg": {
             "components": [
-                {
-                    "component_type": "arm",
-                    "urdf_path": "UniversalRobots/UR10/UR10.urdf"
-                },
                 {
                     "component_type": "hand",
                     "urdf_path": "DH_PGI_140_80/DH_PGI_140_80.urdf"
@@ -147,19 +144,13 @@
         },
         "solver_cfg": {
             "arm": {
-                "class_type": "PytorchSolver",
-                "end_link_name": "ee_link",
-                "root_link_name": "base_link",
                 "tcp": [
                     [1.0, 0.0, 0.0, 0.0],
                     [0.0, 1.0, 0.0, 0.0],
                     [0.0, 0.0, 1.0, 0.16],
                     [0.0, 0.0, 0.0, 1.0]
                 ]
             }
-        },
-        "control_parts": {
-            "arm": ["JOINT[1-6]"]
         }
     },
     "sensor": [],

diff --git a/docs/source/_static/robots/dual/facing_forward.png b/docs/source/_static/robots/dual/facing_forward.png
diff --git a/docs/source/_static/robots/dual/mirror.png b/docs/source/_static/robots/dual/mirror.png
diff --git a/docs/source/_static/robots/dual/side_by_side.png b/docs/source/_static/robots/dual/side_by_side.png
diff --git a/docs/source/_static/robots/ur/ur10.png b/docs/source/_static/robots/ur/ur10.png
diff --git a/docs/source/_static/robots/ur/ur10e.png b/docs/source/_static/robots/ur/ur10e.png
diff --git a/docs/source/_static/robots/ur/ur3.png b/docs/source/_static/robots/ur/ur3.png
diff --git a/docs/source/_static/robots/ur/ur3e.png b/docs/source/_static/robots/ur/ur3e.png
diff --git a/docs/source/_static/robots/ur/ur5.png b/docs/source/_static/robots/ur/ur5.png
diff --git a/docs/source/_static/robots/ur/ur5e.png b/docs/source/_static/robots/ur/ur5e.png
diff --git a/docs/source/resources/robot/dual_arm.md b/docs/source/resources/robot/dual_arm.md
@@ -0,0 +1,130 @@
+# Dual-Arm Composition
+
+`DualArmRobotCfg` builds a bimanual robot from a single-arm base config that
+already follows the standard `"arm"` convention. In the current EmbodiChain
+setup, the dual-arm examples are based on the UR family and are assembled onto a
+shared synthetic `base_link` through `URDFCfg`.
+
+The images below show the three documented dual-arm layouts currently used for
+this robot family: a separated side-by-side arrangement, a wide mirrored
+forward-facing arrangement, and a tighter mirrored arrangement for close
+workspace overlap.
+
+<div style="display: flex; justify-content: center; align-items: flex-start; gap: 20px; flex-wrap: wrap;">
+  <figure style="text-align: center; margin: 10px;">
+    <img src="../../_static/robots/dual/side_by_side.png" alt="Side-by-side dual arm layout" style="height: 220px; width: auto;"/>
+    <figcaption><b>Side-by-Side</b></figcaption>
+  </figure>
+  <figure style="text-align: center; margin: 10px;">
+    <img src="../../_static/robots/dual/facing_forward.png" alt="Wide mirrored dual arm layout" style="height: 220px; width: auto;"/>
+    <figcaption><b>Wide Mirrored Layout</b></figcaption>
+  </figure>
+  <figure style="text-align: center; margin: 10px;">
+    <img src="../../_static/robots/dual/mirror.png" alt="Close mirrored dual arm layout" style="height: 220px; width: auto;"/>
+    <figcaption><b>Close Mirrored Layout</b></figcaption>
+  </figure>
+</div>
+
+## Key Features
+
+- **Generic dual-arm builder** from any single-arm `RobotCfg` that exposes one `arm` URDF component, one `control_parts["arm"]`, and one `solver_cfg["arm"]`.
+- **Image-backed mount presets** covering separated, inward-facing, and mirrored-`rz` layouts.
+- **Automatic left/right derivation** for URDF components, control parts, solver configs, and drive properties.
+- **Config-driven construction** through `DualArmRobotCfg.from_dict(...)` with registry-based base robot lookup.
+- **Optional composite `dual_arm` part** for commanding both manipulators together.
+- **Round-trip support** through `to_dict()` / `from_dict()` on the generated config.
+
+## Visual Layouts
+
+- **Side-by-side** keeps both bases offset by `±separation/2` along Y with the same orientation.
+- **Wide mirrored layout** spreads the arms apart while rotating them symmetrically so they open away from each other.
+- **Close mirrored layout** rotates the arms symmetrically toward a shared center workspace for overlapping reach.
+
+## Usage
+
+```python
+from embodichain.lab.sim import SimulationManager, SimulationManagerCfg
+from embodichain.lab.sim.robots import DualArmRobotCfg
+
+sim = SimulationManager(SimulationManagerCfg(headless=True, num_envs=4))
+
+cfg = DualArmRobotCfg.from_dict(
+    {
+        "base_robot": "ur5",
+        "mount": {
+            "preset": "mirrored_rz",
+            "separation": 0.6,
+            "rz": 0.7853981633974483,
+        },
+    }
+)
+robot = sim.add_robot(cfg=cfg)
+```
+
+## Mount Presets
+
+| Preset | Layout |
+|--------|--------|
+| `side_by_side` | Left arm at `+separation/2` in Y, right arm at `-separation/2` in Y, same orientation on both sides. |
+| `facing_inward` | Same `±separation/2` offsets, with yaw `+pi/2` on the left arm and `-pi/2` on the right arm. |
+| `mirrored_rz` | Same `±separation/2` offsets, with yaw `+rz` on the left arm and `-rz` on the right arm. |
+
+The `mount` configuration also supports paired per-arm overrides:
+
+```python
+cfg = DualArmRobotCfg.from_dict(
+    {
+        "base_robot": "ur5",
+        "mount": {
+            "preset": "side_by_side",
+            "separation": 0.6,
+            "left": {"xyz": [0.0, 0.35, 0.0], "rpy": [0.0, 0.0, 0.0]},
+            "right": {"xyz": [0.1, -0.35, 0.0], "rpy": [0.0, 0.0, 0.0]},
+        },
+    }
+)
+```
+
+## Configuration Parameters
+
+| Parameter | Description |
+|-----------|-------------|
+| `base_robot` | Registry key such as `"ur3"` through `"ur10e"`, or `{"type": ..., "init": {...}}` for extra base config overrides. |
+| `mount` | Mount dict consumed by `resolve_mounts`, including `preset`, `separation`, optional `rz`, and optional paired `left` / `right` overrides. |
+| `arm_part` | Base robot manipulator control part name. Default: `"arm"`. |
+| `dual_part` | Whether to emit the concatenated `dual_arm` control part. Default: `True`. |
+
+## Derived Control Parts
+
+For a UR5 base robot with the default preserved joint casing, `DualArmRobotCfg`
+produces:
+
+| Part | Joints |
+|------|--------|
+| `left_arm` | `left_joint1` to `left_joint6` |
+| `right_arm` | `right_joint1` to `right_joint6` |
+| `dual_arm` | concatenation of the 12 joints above |
+
+For other base robots, the builder preserves the source URDF naming policy and
+applies the `left_` / `right_` prefixes consistently with the assembled URDF.
+
+## Programmatic Build Path
+
+```python
+from embodichain.lab.sim.robots import URRobotCfg, build_dual_arm_cfg, resolve_mounts
+
+base = URRobotCfg.from_dict({"robot_type": "ur5"})
+mounts = resolve_mounts({"preset": "facing_inward", "separation": 0.6})
+cfg = build_dual_arm_cfg(base, mounts, dual_part=False)
+```
+
+## Adding a New Base Robot
+
+A single-arm robot becomes dual-arm-ready by:
+
+1. following the existing `"arm"` convention in its single-arm cfg,
+2. exposing `control_parts["arm"]` and `solver_cfg["arm"]`,
+3. adding one registry entry in `embodichain/lab/sim/robots/dual_arm.py`.
+
+That keeps the dual-arm path generic: no extra mixin or robot-specific dual-arm
+class is required.
diff --git a/docs/source/resources/robot/index.rst b/docs/source/resources/robot/index.rst
@@ -6,6 +6,8 @@ Supported Robots
 .. toctree::
    :maxdepth: 1
 
+   UR Family <ur_robot.md>
    Dexforce W1 <dexforce_w1.md>
    CobotMagic <cobotmagic.md>
+   Dual-Arm Composition <dual_arm.md>
 
diff --git a/docs/source/resources/robot/ur_robot.md b/docs/source/resources/robot/ur_robot.md
@@ -0,0 +1,93 @@
+# UR Family (UR3 / UR5 / UR10 + e variants)
+
+`URRobotCfg` covers six Universal Robots manipulators in one configuration class:
+`ur3`, `ur3e`, `ur5`, `ur5e`, `ur10`, and `ur10e`. The images below show the exact
+variants currently documented in EmbodiChain: the compact UR3 pair, the mid-reach
+UR5 pair, and the long-reach UR10 pair, with darker classic models and brighter
+silver-arm e-series renders.
+
+<div style="display: flex; justify-content: center; align-items: flex-start; gap: 20px; flex-wrap: wrap;">
+  <figure style="text-align: center; margin: 10px;">
+    <img src="../../_static/robots/ur/ur3.png" alt="UR3" style="height: 220px; width: auto;"/>
+    <figcaption><b>UR3</b></figcaption>
+  </figure>
+  <figure style="text-align: center; margin: 10px;">
+    <img src="../../_static/robots/ur/ur3e.png" alt="UR3e" style="height: 220px; width: auto;"/>
+    <figcaption><b>UR3e</b></figcaption>
+  </figure>
+  <figure style="text-align: center; margin: 10px;">
+    <img src="../../_static/robots/ur/ur5.png" alt="UR5" style="height: 220px; width: auto;"/>
+    <figcaption><b>UR5</b></figcaption>
+  </figure>
+  <figure style="text-align: center; margin: 10px;">
+    <img src="../../_static/robots/ur/ur5e.png" alt="UR5e" style="height: 220px; width: auto;"/>
+    <figcaption><b>UR5e</b></figcaption>
+  </figure>
+  <figure style="text-align: center; margin: 10px;">
+    <img src="../../_static/robots/ur/ur10.png" alt="UR10" style="height: 220px; width: auto;"/>
+    <figcaption><b>UR10</b></figcaption>
+  </figure>
+  <figure style="text-align: center; margin: 10px;">
+    <img src="../../_static/robots/ur/ur10e.png" alt="UR10e" style="height: 220px; width: auto;"/>
+    <figcaption><b>UR10e</b></figcaption>
+  </figure>
+</div>
+
+## Key Features
+
+- **One config, six UR variants** selected through `robot_type`.
+- **Image-matched family lineup** from the shortest-reach UR3 pair to the longest-reach UR10 pair.
+- **Classic and e-series styling** with darker legacy arms and brighter silver-arm e-series renders.
+- **Analytic UR inverse kinematics** through `URSolverCfg` and the Warp-based UR solver path.
+- **Simulation-ready defaults** for URDF selection, control parts, drive properties, and rigid-body attributes.
+
+## Visual Differences Across Variants
+
+- **UR3 / UR3e** are the most compact renders in the set and keep the wrist close to the base.
+- **UR5 / UR5e** extend the shoulder-to-wrist span while keeping the same 6-axis arm layout.
+- **UR10 / UR10e** show the longest upper-arm and forearm links, matching the largest reach tier in the family.
+- **Classic models (`ur3`, `ur5`, `ur10`)** appear darker overall, especially on the arm links.
+- **e-series models (`ur3e`, `ur5e`, `ur10e`)** use brighter silver links and lighter joint accents in these renders.
+
+## Usage
+
+```python
+from embodichain.lab.sim import SimulationManager, SimulationManagerCfg
+from embodichain.lab.sim.robots import URRobotCfg
+
+sim = SimulationManager(SimulationManagerCfg(headless=True, num_envs=4))
+cfg = URRobotCfg.from_dict({"robot_type": "ur5"})
+robot = sim.add_robot(cfg=cfg)
+```
+
+## Robot Parameters
+
+| Parameter | Description |
+|-----------|-------------|
+| `robot_type` | UR variant: `ur3`, `ur3e`, `ur5`, `ur5e`, `ur10`, or `ur10e` |
+| Number of joints | 6 revolute joints plus the fixed `ee_link` |
+| Control parts | `arm` (6 joints) |
+| Root / end link | `base_link` / `ee_link` |
+| Solver | `URSolverCfg` (analytic UR IK) |
+| Drive `max_effort` | UR3/UR3e about 56 N.m, UR5/UR5e about 150 N.m, UR10/UR10e about 330 N.m |
+
+> **Note:** The `ur5` URDF uses lowercase joint names (`joint1` to `joint6`), while
+> the other variants use `Joint1` to `Joint6`. `URRobotCfg._build_defaults`
+> selects the correct naming scheme automatically.
+
+## Variants at a Glance
+
+| `robot_type` | Preview | URDF | Reach (m) | Payload (kg) |
+|--------------|---------|------|-----------|--------------|
+| `ur3` | Compact classic render | `UniversalRobots/UR3/UR3.urdf` | ~0.5 | 3 |
+| `ur3e` | Compact e-series render | `UniversalRobots/UR3e/UR3e.urdf` | ~0.5 | 3 |
+| `ur5` | Mid-size classic render | `UniversalRobots/UR5/UR5.urdf` | ~0.85 | 5 |
+| `ur5e` | Mid-size e-series render | `UniversalRobots/UR5e/UR5e.urdf` | ~0.85 | 5 |
+| `ur10` | Long-reach classic render | `UniversalRobots/UR10/UR10.urdf` | ~1.3 | 10 |
+| `ur10e` | Long-reach e-series render | `UniversalRobots/UR10e/UR10e.urdf` | ~1.3 | 10 |
+
+## See Also
+
+- :doc:`/guides/add_robot` - Adding a new robot (quick reference)
+- :doc:`/tutorial/add_robot` - Adding a new robot (full tutorial)
+- :doc:`/overview/sim/solvers/index` - IK solver reference
diff --git a/embodichain/lab/sim/cfg.py b/embodichain/lab/sim/cfg.py
@@ -1049,10 +1049,16 @@ class URDFCfg:
 
     name_case: dict[str, str] = field(
         default_factory=lambda: {
-            "joint": "upper",
-            "link": "lower",
+            "joint": "original",
+            "link": "original",
         }
     )
+    """Case normalization policy applied to joint/link names during URDF assembly.
+
+    Supported values per key are ``"upper"``, ``"lower"`` or ``"original"``
+    (legacy alias ``"none"``). The default upper-cases joints and lower-cases
+    links. Set ``{"joint": "original"}`` to preserve the source URDF casing.
+    """
 
     def __init__(
         self,
@@ -1117,8 +1123,8 @@ def __init__(
 
         if name_case is None:
             self.name_case = {
-                "joint": "upper",
-                "link": "lower",
+                "joint": "original",
+                "link": "original",
             }
         else:
             self.name_case = name_case

diff --git a/embodichain/lab/sim/robots/__init__.py b/embodichain/lab/sim/robots/__init__.py
@@ -16,5 +16,13 @@
 
 from .dexforce_w1 import *
 from .cobotmagic import CobotMagicCfg
+from .ur_robot import URRobotCfg
+from .dual_arm import DualArmRobotCfg, build_dual_arm_cfg
 
-__all__ = ["DexforceW1Cfg", "CobotMagicCfg"]
+__all__ = [
+    "DexforceW1Cfg",
+    "CobotMagicCfg",
+    "URRobotCfg",
+    "DualArmRobotCfg",
+    "build_dual_arm_cfg",
+]
diff --git a/embodichain/lab/sim/robots/cobotmagic.py b/embodichain/lab/sim/robots/cobotmagic.py
@@ -88,23 +88,23 @@ def _build_defaults(self, init_dict: dict | None = None) -> None:
         )
         self.control_parts = {
             "left_arm": [
-                "LEFT_JOINT1",
-                "LEFT_JOINT2",
-                "LEFT_JOINT3",
-                "LEFT_JOINT4",
-                "LEFT_JOINT5",
-                "LEFT_JOINT6",
+                "left_joint1",
+                "left_joint2",
+                "left_joint3",
+                "left_joint4",
+                "left_joint5",
+                "left_joint6",
             ],
-            "left_eef": ["LEFT_JOINT7", "LEFT_JOINT8"],
+            "left_eef": ["left_joint7", "left_joint8"],
             "right_arm": [
-                "RIGHT_JOINT1",
-                "RIGHT_JOINT2",
-                "RIGHT_JOINT3",
-                "RIGHT_JOINT4",
-                "RIGHT_JOINT5",
-                "RIGHT_JOINT6",
+                "right_joint1",
+                "right_joint2",
+                "right_joint3",
+                "right_joint4",
+                "right_joint5",
+                "right_joint6",
             ],
-            "right_eef": ["RIGHT_JOINT7", "RIGHT_JOINT8"],
+            "right_eef": ["right_joint7", "right_joint8"],
         }
         self.solver_cfg = {
             "left_arm": OPWSolverCfg(
@@ -126,22 +126,22 @@ def _build_defaults(self, init_dict: dict | None = None) -> None:
         self.min_velocity_iters = 2
         self.drive_pros = JointDrivePropertiesCfg(
             stiffness={
-                "LEFT_JOINT[1-6]": 7e4,
-                "RIGHT_JOINT[1-6]": 7e4,
-                "LEFT_JOINT[7-8]": 3e2,
-                "RIGHT_JOINT[7-8]": 3e2,
+                "left_joint[1-6]": 7e4,
+                "right_joint[1-6]": 7e4,
+                "left_joint[7-8]": 3e2,
+                "right_joint[7-8]": 3e2,
             },
             damping={
-                "LEFT_JOINT[1-6]": 1e3,
-                "RIGHT_JOINT[1-6]": 1e3,
-                "LEFT_JOINT[7-8]": 3e1,
-                "RIGHT_JOINT[7-8]": 3e1,
+                "left_joint[1-6]": 1e3,
+                "right_joint[1-6]": 1e3,
+                "left_joint[7-8]": 3e1,
+                "right_joint[7-8]": 3e1,
             },
             max_effort={
-                "LEFT_JOINT[1-6]": 3e6,
-                "RIGHT_JOINT[1-6]": 3e6,
-                "LEFT_JOINT[7-8]": 3e3,
-                "RIGHT_JOINT[7-8]": 3e3,
+                "left_joint[1-6]": 3e6,
+                "right_joint[1-6]": 3e6,
+                "left_joint[7-8]": 3e3,
+                "right_joint[7-8]": 3e3,
             },
         )
         self.attrs = RigidBodyAttributesCfg(