Add full naming convention aliases for robot limbs #641

iory · 2026-01-06T04:58:38Z

No description provided.

Add right_arm, left_arm, right_leg, left_leg properties to RobotModel base class with isinstance type checking and NotImplementedError handling. Also add backward-compatible aliases to individual robot models: - PR2: right_arm, left_arm, right_arm_with_torso, left_arm_with_torso - Panda, Fetch, Kuka: arm, arm_with_torso (for single-arm robots) - Nextage, R8_6: right_arm, left_arm This allows using full names (robot.right_arm) while maintaining backward compatibility with abbreviated names (robot.rarm).

Test right_arm, left_arm, arm aliases and their end_coords variants for dual-arm robots (PR2) and single-arm robots (Fetch, Kuka). Also verify that non-existent limbs (legs) return None.

- batch_ik_demo.py: Use arm/right_arm instead of rarm - pybullet_robot_interface.py: Use arm/arm_end_coords instead of rarm

Copilot

Pull request overview

This PR adds full naming convention aliases for robot limbs to improve code readability and intuitiveness. The main changes introduce properties like right_arm, left_arm, and arm as aliases for the abbreviated forms rarm, larm, and rarm (for single-arm robots), while maintaining full backward compatibility with the original naming.

Adds base class properties in RobotModel that provide default alias behavior for all robot models
Implements specific aliases in individual robot model classes to override base behavior where needed
Updates examples and notebooks to demonstrate the new naming convention
Fixes a typo in PR2's gripper_distance() error message

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
`skrobot/model/robot_model.py`	Adds base class properties for limb and end_coords aliases with fallback behavior
`skrobot/models/pr2.py`	Adds `right_arm`, `left_arm` aliases and updates `gripper_distance()` to accept new names; fixes error message typo
`skrobot/models/fetch.py`	Adds `arm` and `arm_with_torso` aliases for single-arm robot
`skrobot/models/panda.py`	Adds `arm` alias for single-arm robot
`skrobot/models/kuka.py`	Adds `arm` alias for single-arm robot
`skrobot/models/nextage.py`	Adds `right_arm` and `left_arm` aliases for dual-arm robot
`skrobot/models/r8_6.py`	Adds `right_arm`, `left_arm`, and torso variants for dual-arm robot
`tests/skrobot_tests/model_tests/test_robot_model.py`	Adds comprehensive tests for new naming convention aliases
`examples/pybullet_robot_interface.py`	Updates to use `arm` and `arm_end_coords` for Kuka robot
`examples/pr2_inverse_kinematics.py`	Updates to use `right_arm_end_coords` throughout
`examples/batch_ik_demo.py`	Updates to use new full naming convention for all robots
`examples/grasp_and_pull_box.py`	Updates gripper calls and variable names to use new convention
`examples/collision_free_trajectory.py`	Updates variable names from `rarm_` to `right_arm_`
`examples/notebooks/jupyter_collision_free_with_base.ipynb`	Updates notebook to use `right_arm_end_coords` and `arm_point_history`
`examples/notebooks/colab_jupyter_viewer_demo.ipynb`	Updates notebook to use `right_arm_end_coords` and new gripper naming

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Copilot · 2026-01-06T05:03:05Z

skrobot/model/robot_model.py

+    # New naming convention properties (forward compatibility)
+    # These provide access using full names (right_arm, left_arm, etc.)
+    # while maintaining backward compatibility with abbreviated names.


The comment says "forward compatibility" but this is actually about providing more intuitive naming while maintaining backward compatibility with the abbreviated names. Consider updating the comment to clarify that these properties provide improved naming conventions (full names like "right_arm") while the abbreviated names ("rarm") remain available for backward compatibility.

Suggested change

# New naming convention properties (forward compatibility)

# These provide access using full names (right_arm, left_arm, etc.)

# while maintaining backward compatibility with abbreviated names.

# New naming convention properties with more intuitive full names.

# These provide access using full names (right_arm, left_arm, etc.)

# while keeping the abbreviated names (rarm, larm, etc.) available for

# backward compatibility.

Copilot · 2026-01-06T05:03:05Z

skrobot/models/pr2.py

+    right_arm = rarm
+    left_arm = larm
+    right_arm_with_torso = rarm_with_torso
+    left_arm_with_torso = larm_with_torso
+


Direct assignment of cached_property descriptors may not work as intended. When assigning right_arm = rarm where rarm is decorated with @cached_property, both attributes share the same descriptor object. However, the caching behavior of cached_property typically relies on the attribute name for storing cached values in the instance dictionary. This approach may lead to unexpected behavior or multiple cached instances.

Consider using explicit property wrappers instead:

@cached_property def right_arm(self): return self.rarm

This ensures proper caching semantics and makes the aliasing relationship explicit.

Suggested change

right_arm = rarm

left_arm = larm

right_arm_with_torso = rarm_with_torso

left_arm_with_torso = larm_with_torso

@cached_property

def right_arm(self):

return self.rarm

@cached_property

def left_arm(self):

return self.larm

@cached_property

def right_arm_with_torso(self):

return self.rarm_with_torso

@cached_property

def left_arm_with_torso(self):

return self.larm_with_torso

Copilot · 2026-01-06T05:03:05Z

skrobot/models/fetch.py

+    arm = rarm
+    arm_with_torso = rarm_with_torso
+
+    @property


Direct assignment of cached_property descriptors may not work as intended. When assigning arm = rarm and arm_with_torso = rarm_with_torso where these are decorated with @cached_property, both attributes share the same descriptor object. This may lead to unexpected caching behavior.

Consider using explicit property wrappers instead for clarity and to ensure proper caching semantics.

Suggested change

arm = rarm

arm_with_torso = rarm_with_torso

@property

@property

def arm(self):

return self.rarm

@property

def arm_with_torso(self):

return self.rarm_with_torso

@property

Copilot · 2026-01-06T05:03:06Z

skrobot/models/panda.py

        return model
+
+    # New naming convention aliases (backward compatible)
+    arm = rarm


Direct assignment of cached_property descriptor may not work as intended. When assigning arm = rarm where rarm is decorated with @cached_property, both attributes share the same descriptor object, which may lead to unexpected caching behavior.

Consider using an explicit property wrapper instead for clarity and to ensure proper caching semantics.

Suggested change

arm = rarm

@property

def arm(self):

return self.rarm

Copilot · 2026-01-06T05:03:06Z

skrobot/models/kuka.py

        return self.angle_vector(av)
+
+    # New naming convention aliases (backward compatible)
+    arm = rarm


Direct assignment of cached_property descriptor may not work as intended. When assigning arm = rarm where rarm is decorated with @cached_property, both attributes share the same descriptor object, which may lead to unexpected caching behavior.

Consider using an explicit property wrapper instead for clarity and to ensure proper caching semantics.

Suggested change

arm = rarm

@property

def arm(self):

return self.rarm

Copilot · 2026-01-06T05:03:06Z

skrobot/models/nextage.py

+    right_arm = rarm
+    left_arm = larm
+
+    @property


Direct assignment of cached_property descriptors may not work as intended. When assigning right_arm = rarm and left_arm = larm where these are decorated with @cached_property, both attributes share the same descriptor object, which may lead to unexpected caching behavior.

Consider using explicit property wrappers instead for clarity and to ensure proper caching semantics.

Suggested change

right_arm = rarm

left_arm = larm

@property

@property

def right_arm(self):

return self.rarm

@property

def left_arm(self):

return self.larm

@property

Copilot · 2026-01-06T05:03:07Z

skrobot/model/robot_model.py

+            limb = getattr(self, attr_name, None)
+            if isinstance(limb, RobotModel):
+                return limb
+        except NotImplementedError:


'except' clause does nothing but pass and there is no explanatory comment.

Copilot · 2026-01-06T05:03:07Z

skrobot/model/robot_model.py

+            coords = getattr(self, attr_name, None)
+            if isinstance(coords, CascadedCoords):
+                return coords
+        except NotImplementedError:


'except' clause does nothing but pass and there is no explanatory comment.

iory added 4 commits January 6, 2026 13:40

Add test for limb naming convention aliases

2690db0

Test right_arm, left_arm, arm aliases and their end_coords variants for dual-arm robots (PR2) and single-arm robots (Fetch, Kuka). Also verify that non-existent limbs (legs) return None.

Update examples to use new limb naming convention

8e9a8f6

- batch_ik_demo.py: Use arm/right_arm instead of rarm - pybullet_robot_interface.py: Use arm/arm_end_coords instead of rarm

Update examples to use new naming convention (right_arm, left_arm)

d961af4

iory requested a review from Copilot January 6, 2026 04:58

Copilot started reviewing on behalf of iory January 6, 2026 04:59 View session

Copilot AI reviewed Jan 6, 2026

View reviewed changes

Address review: use @Property wrappers instead of direct assignment

859dbe7

iory merged commit a3fb53f into main Jan 6, 2026
19 checks passed

iory deleted the model branch January 6, 2026 05:21

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-    right_arm = rarm
-    left_arm = larm
-    right_arm_with_torso = rarm_with_torso
-    left_arm_with_torso = larm_with_torso
+    @cached_property
+    def right_arm(self):
+        return self.rarm
+    @cached_property
+    def left_arm(self):
+        return self.larm
+    @cached_property
+    def right_arm_with_torso(self):
+        return self.rarm_with_torso
+    @cached_property
+    def left_arm_with_torso(self):
+        return self.larm_with_torso

Add full naming convention aliases for robot limbs #641

Add full naming convention aliases for robot limbs #641

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iory commented Jan 6, 2026

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