Implementation:ARISE Initiative Robosuite LeggedManipulatorModel
| Knowledge Sources | |
|---|---|
| Domains | Robotics, Robot Modeling, Legged Robots |
| Last Updated | 2026-02-15 07:00 GMT |
Overview
The LeggedManipulatorModel class extends the manipulator model with methods for removing joint actuation and free joints, enabling the creation of humanoid robot variants with different levels of body part actuation.
Description
LeggedManipulatorModel inherits from ManipulatorModel and adds two key methods for modifying the robot's MJCF model at construction time. The _remove_joint_actuation method strips all joints and actuators (motors and position controllers) matching a given body part name from the model. It removes the joints from the worldbody, removes corresponding motor and position actuators, removes related tendons, removes joint equality constraints, and removes joint position/velocity/actuator force sensors. This enables creating robot variants where certain body parts (e.g., legs, head, torso) are frozen in their initial configuration.
The _remove_free_joint method removes all free joints from the worldbody, converting the robot from a free-floating body to one that is fixed in space. This is used in conjunction with _remove_joint_actuation to create variants like GR1FixedLowerBody where the humanoid's upper body is fixed in place.
The class also exposes a legs_joints property that returns the list of leg joint names, accessed from the internal _legs_joints attribute.
Usage
Use this class as the base for legged humanoid robot models. Subclasses can call _remove_joint_actuation("leg") and _remove_free_joint() in their constructors to create fixed-body or arms-only variants of a full humanoid model.
Code Reference
Source Location
- Repository: ARISE_Initiative_Robosuite
- File: robosuite/models/robots/manipulators/legged_manipulator_model.py
Signature
class LeggedManipulatorModel(ManipulatorModel):
def __init__(self, fname, idn=0)
def _remove_joint_actuation(self, part_name: str) -> None
def _remove_free_joint(self) -> None
Import
from robosuite.models.robots.manipulators.legged_manipulator_model import LeggedManipulatorModel
I/O Contract
Inputs
| Name | Type | Required | Description |
|---|---|---|---|
| fname | str | Yes | Path to the MJCF XML file for this robot |
| idn | int or str | No | Unique identification number or string (default: 0) |
| part_name | str | Yes (_remove_joint_actuation) | Body part keyword to match for removal (e.g., "leg", "head", "torso") |
Outputs
| Name | Type | Description |
|---|---|---|
| legs_joints | list | List of leg joint names for this robot |
Usage Examples
from robosuite.models.robots.manipulators.legged_manipulator_model import LeggedManipulatorModel
# Typically used as a base class for humanoid robots
class MyHumanoid(LeggedManipulatorModel):
arms = ["right", "left"]
def __init__(self, idn=0):
super().__init__("path/to/humanoid.xml", idn=idn)
class MyHumanoidArmsOnly(MyHumanoid):
def __init__(self, idn=0):
super().__init__(idn=idn)
# Remove leg actuation and freeze in place
self._remove_joint_actuation("leg")
self._remove_joint_actuation("head")
self._remove_joint_actuation("torso")
self._remove_free_joint()