Sixi robot now has a URDF description and can be found on the ROS wiki.
ROS (Robot Operating System) was first developed by Willow Garage, a Boston robotics company. Though Willow Garage no longer exists, the ROS has been so successful that it has outlived its creator.
Since ROS is such a popular tool, I hired sachinkumar1235 on Fiverr who built the URDF package. It includes decimated STL files created by Andre.
