it’s a collection of different standards that define its body , its voice , and its rules . Here are the four most common types of schemas used by engineers at places like NASA , Boston Dynamics , and Tesla . 1. The Physical Schema: URDF (XML) The Unified Robot Description Format (URDF) is the industry standard for defining a robot's physical structure. It tells the software where the joints are, how heavy the arms are, and how they are connected. Example: A "Leg" joint in a real robot (XML format) XML < link name = "upper_leg" > < inertial > < mass value = "2.5" /> < origin xyz = "0 0 0.1" /> </ inertial > </ link > < joint name = "knee_joint" type = "revolute" > < parent link = "upper_leg" /> < child link = "lower_leg" /> < axis xyz = "0 1 0" /> < limit effort = "150" lower = ...