URDF全称为Unified Robot Description Format，中文可以翻译为“统一机器人描述格式”。与计算机文件中的.txt文本格式、.jpg图像格式等类似，URDF是一种基于XML规范、用于描述机器人结构的格式。根据该格式的设计者所言，设计这一格式的目的在于提供一种尽可能通用（as general as possible）的机器人描述规范。
<?xml version="1.0" encoding="utf-8"?>
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<robot name="ur5e_robot"><!--Base UR robot series xacro macro.NOTE: this is NOT a URDF. It cannot directly be loaded by consumersexpecting a flattened '.urdf' file. See the top-level '.xacro' for that(but note: that .xacro must still be processed by the xacro command).For use in '.launch' files: use one of the 'load_urX.launch' conveniencelaunch files.This file models the base kinematic chain of a UR robot, which then getsparameterised by various configuration files to convert it into a UR3(e),UR5(e), UR10(e) or UR16e.NOTE: the default kinematic parameters (ie: link lengths, frame locations,offets, etc) do not correspond to any particular robot. They are defaultsonly. There WILL be non-zero offsets between the Forward Kinematics resultsin TF (ie: robot_state_publisher) and the values reported by the TeachPendant.For accurate (and robot-specific) transforms, the 'kinematics_parameters_file'parameter MUST point to a .yaml file containing the appropriate values forthe targetted robot.If using the UniversalRobots/Universal_Robots_ROS_Driver, follow the stepsdescribed in the readme of that repository to extract the kinematiccalibration from the controller and generate the required .yaml file.Main author of the migration to yaml configs: Ludovic Delval.Contributors to previous versions (in no particular order):- Felix Messmer- Kelsey Hawkins- Wim Meeussen- Shaun Edwards- Nadia Hammoudeh Garcia- Dave Hershberger- G. vd. Hoorn- Philip Long- Dave Coleman- Miguel Prada- Mathias Luedtke- Marcel Schnirring- Felix von Drigalski- Felix Exner- Jimmy Da Silva- Ajit Krisshna N L- Muhammad Asif Rana--><!--NOTE: the macro defined in this file is NOT part of the public API of thispackage. Users CANNOT rely on this file being available, or stored inthis location. Nor can they rely on the existence of the macro.--><transmission name="shoulder_pan_trans"><type>transmission_interface/SimpleTransmission</type><joint name="shoulder_pan_joint"><hardwareInterface>hardware_interface/PositionJointInterface</hardwareInterface></joint><actuator name="shoulder_pan_motor"><mechanicalReduction>1</mechanicalReduction></actuator></transmission><transmission name="shoulder_lift_trans"><type>transmission_interface/SimpleTransmission</type><joint name="shoulder_lift_joint"><hardwareInterface>hardware_interface/PositionJointInterface</hardwareInterface></joint><actuator name="shoulder_lift_motor"><mechanicalReduction>1</mechanicalReduction></actuator></transmission><transmission name="elbow_trans"><type>transmission_interface/SimpleTransmission</type><joint name="elbow_joint"><hardwareInterface>hardware_interface/PositionJointInterface</hardwareInterface></joint><actuator name="elbow_motor"><mechanicalReduction>1</mechanicalReduction></actuator></transmission><transmission name="wrist_1_trans"><type>transmission_interface/SimpleTransmission</type><joint name="wrist_1_joint"><hardwareInterface>hardware_interface/PositionJointInterface</hardwareInterface></joint><actuator name="wrist_1_motor"><mechanicalReduction>1</mechanicalReduction></actuator></transmission><transmission name="wrist_2_trans"><type>transmission_interface/SimpleTransmission</type><joint name="wrist_2_joint"><hardwareInterface>hardware_interface/PositionJointInterface</hardwareInterface></joint><actuator name="wrist_2_motor"><mechanicalReduction>1</mechanicalReduction></actuator></transmission><transmission name="wrist_3_trans"><type>transmission_interface/SimpleTransmission</type><joint name="wrist_3_joint"><hardwareInterface>hardware_interface/PositionJointInterface</hardwareInterface></joint><actuator name="wrist_3_motor"><mechanicalReduction>1</mechanicalReduction></actuator></transmission><!-- links: main serial chain --><link name="base_link"/><link name="base_link_inertia"><visual><origin rpy="0 0 3.14159265359" xyz="0 0 0"/><geometry><mesh filename="package://ur_description/meshes/ur5e/visual/base.dae"/></geometry><material name="LightGrey"><color rgba="0.7 0.7 0.7 1.0"/></material></visual><collision><origin rpy="0 0 3.14159265359" xyz="0 0 0"/><geometry><mesh filename="package://ur_description/meshes/ur5e/collision/base.stl"/></geometry></collision><inertial><mass value="4.0"/><origin rpy="0 0 0" xyz="0 0 0"/><inertia ixx="0.00443333156" ixy="0.0" ixz="0.0" iyy="0.00443333156" iyz="0.0" izz="0.0072"/></inertial></link>&l
