Unity-Robotics-Hub/tutorials/urdf_importer/urdf_tutorial.md

Importing a Niryo One Robot using URDF Importer

Requirements

• Unity Version 2020.2+
• URDF Importer repo
• Niryo One URDF files from Niryo One ROS
• Working ROS environment

Setting up the URDF Importer in Unity Editor

• Integrate the URDF Importer following these instructions
• Create a new directory in Assets and name it URDF
• Clone the Niryo One ROS repo and copy the niryo_one_description directory into Assets/URDF
• This directory only includes a .urdf.xacro file which will need to be converted into a .urdf file before we can import it
  • Run the following command to convert Xacro to URDF, rosrun xacro xacro --inorder -o PATH/TO/niryo_one.urdf PATH/TO/niryo_one.urdf.xacro
  • Copy the generated niryo_one.urdf file to Assets/URDF
  • Right click on the this file and select Import Robot from URDF
  • Select the co-ordinate system in which the meshes were designed. Default mesh orientation is Y-up which is supported by Unity but some packages often use Z-up and X-up configuration. For more information.
  • Select the Convex Mesh Decomposer you want to use for the imported robot. More information can be found here.
  • Click Import

Using the Controller

• By default a robot imported using the URDF Importer is loaded without any constraints or controller.
  • A controller is pre-built in Unity URDF Importer to help showcase the movement of robots in Unity.
• To add the controller to an imported robot click the Enable button in the Inspector window in front of the Controller Script option. This will add a Controller Script, FKrobot and Joint Control at runtime.
• To prevent the joints from slipping set the Stiffness and Damping to 100,000 and 10,000 respectively.
• To be able to apply forces to the joints set the Force Limit to 10,000.
• To prevent the robot from falling over, in the GameObject tree expand niryo_one -> world -> base_link and set the toggle for Immovable for the base_link.
• Press the play button to start the scene.
  • Use the left and right arrow keys to select the articulation body you want to move.
  • Use the up and down keys to move the articulation body clockwise and counterclockwise.

A guide to making a custom controller can be found here

Forward Kinematics script

Forward Kinematics scripts gives you the ability to see the current position of the end effector based on forward kinematics of the robot. You can use it to compare the end effector position of the robot of the articulation body to make sure the importer is working correctly.