DexRobot URDF Models

This repository contains URDF models for a dexterous robotic hand system, including both left and right hand configurations. The models are compatible with standard URDF toolchains and have been tested with MuJoCo.

Quickstart

The URDF models can be visualized using MuJoCo’s simulate tool:

# For left hand
simulate urdf/dexhand021_left.urdf

# For right hand
simulate urdf/dexhand021_right.urdf

Note: After launching the simulator, hit the ‘Pause’ button first, then ‘Reset’ to properly visualize the model in its initial configuration.

Models

Full Model

The full model provides high-fidelity mesh files suitable for rendering and visualization. It includes detailed geometry for all components of the hand.

Simplified Model

A simplified version optimized for simulation is also provided. This model reduces geometric complexity while maintaining kinematic accuracy, making it more efficient for physics simulations. Solidworks project files for these simplified models are included in the repository.

Model Conventions

Naming Convention

The model follows a systematic naming convention for links and joints:

  • Base Format: [lr]_[type]_[component]

    • [lr]: ‘l’ for left hand, ‘r’ for right hand

    • [type]: ‘p’ for palm components, ‘f’ for finger components

    • [component]: specific component identifier

Component Numbering

  • Thumb Rotation: *_1_1

  • Finger Spread: [2345]_1 (for index, middle, ring, and pinky fingers)

  • Metacarpophalangeal (MCP) Joints: [12345]_2

  • Proximal & Distal Joints: [12345]_[34] (for all fingers)

    • Note: While proximal and distal joints are mechanically coupled in the physical system, this coupling is not reflected in the URDF model

Frame Convention

The model primarily follows the Denavit-Hartenberg (DH) convention for frame assignments:

Base Frame

  • Origin: Located at the wrist

  • Z-axis: Points toward fingertips

  • Thumb Orientation: Inclines toward negative X-axis for both hands

Additional Resources

The repository includes utility scripts in the utils/ directory for URDF file processing and analysis. These tools can help with tasks such as updating mesh paths and analyzing model properties.

Notes for Users

  • Mesh files are referenced relative to the URDF location using ../meshes/

  • The models are compatible with major robotics simulation environments that support URDF

  • While the URDF models don’t enforce joint coupling, users can implement this in their control software

  • The utility scripts can be modified as needed to accommodate specific requirements