Freecad to Gazebo exporter

Introduction

Freecad to gazebo exporter is a tool for exporting freecad assembly project to gazebo/ros model.

Design Rules

This project is in its early stage therefore specific design rules must be followed to work with it.

• The assmbly file must be created with A2Plus (freecad's prefered assembly workspace).
• Parts of the assembly must be in separate files.
• Imovable parts of the main assembly must be made in separate subasssemblies.
• Joints should be represented by AxisConsident constraints with lock rotation turned off.
• For URDF files to work properly, tree structure must be maintained (ie. parent and childs of constraints must follow tree structure).

Requirements

• Freecad with A2Plus workspace installed

Usage

To generate SDF and URDF model from freecad assembly use python call:

freecad_exporter.export_gazebo_model(freecad_assembly_file, model_destination_folder, config)

Note: Only links and joints are generated in the SDF model. To use the model with ros, use the URDF model.

Config specification

{
    "name": "robot_name",
    "joints_limits": {"upper": 90, "lower": -90, "effort": 10, "velocity": 5},
    "transmission": {
        "type": "transmission_interface/SimpleTransmission",
        "hardware_interface": "hardware_interface/PositionJointInterface"
    },
    "joints_config": {
        "type": "position_controllers/JointGroupPositionController",
        "grouped": true
    },
    "joints_pid": {"p": 20.0, "i": 10.0, "d": 0.0, "i_clamp": 0.0},
    "root_link": "base_link",
    "ros_package": "humanoid_17dof_description",
    "sdf_only": false,
    "export": true
}

sdf_only: Export only SDF.

export: Export mesh files.

Future plans

• Extend collada exporter to export materials from assemblies.
• Create a FreeCAD workbench to interactively assign joints and export to gazebo.
• Reduce set of design rules by making it more robust and general purpose.
• Support any valid structures of assemblies.