ROS official website. According to the query of ros official website, imagine the URDF model of ROS Ackerman car model data-Ackerman four-wheel car model can be downloaded from ROS official website. Ackerman car refers to a car made of Ackerman steering geometry structure, which is a common front wheel steering structure on the road. Ackerman steering mechanism is to solve the problem that different steering radii of the left and right steering wheels lead to different angles of the left and right steering wheels.