In this video we’ll start changing the factory world so that we can use it in the coming weeks for navigation and picking and placing parts with the three robots.

There are too many obstacles in the factory right now for the turtlebot (that will be added in later weeks) to come close to Robot 1, so some cleanup is needed.

To get the factory simulation ready the following tasks need to be done:

• Remove unneeded bins
• Move bin to turtlebot delivery station
• Add a pedestal
• Add the second robot

We suggest opening the URDF (.xacro file) using a text editor with support for XML highlighting, for example Atom, since it makes reading the file easier

A few notable parts of the URDF are:

• A link named “world“: a link that everything else is connected to
• There are also links created that instantiate other URDF models like the conveyor belt
• After importing all of the building blocks of the world, it is important to then connect them to the world using joints
• The “parent link=‘..'” specifies to what something should be connected and the “child link=‘..'” specifies what it is that should be connected to the parent.
• the origin element describes the relative offset between the parent and the child

To remove a model from a URDF world two things must be removed:

• The joint that connects it to its parent
• The “macro call” that adds it to the world (model instantiations)

To remove four bins, the four model instantiations (ie: macro calls) and the four joints need to be removed.

We leave one bin and relocate it to where it should be (behind the pallet with the crates) by changing the x and y coordinates of its origin element.

A useful tool is “check_urdf“, which can check if a URDF is valid. To do this, first convert the XACRO file to URDF, and then run check_urdf.