學習古月居ROS機械臂課程
保存和加載rviz配置：https://www.theconstructsim.com/ros-qa-125-save-and-load-rviz-configuration/
urdf右手系：
x正方向朝右（紅色）， y 正方向向內（綠色）， z軸正方向朝上（藍色）
檢查urdf:
check_urdf ur3.urdf
查看模型結構：
urdf_to_graphiz ur3.urdf
支持的mesh格式：
The meshes can be imported in a number of different formats. STL is fairly common, but the engine also supports DAE, which can have its own color data, meaning you don’t have to specify the color/material. Often these are in separate files. These meshes reference the .tif files also in the meshes folder.
這里的axis定義了關節的旋轉軸，與origin中的rpy無關：
<joint name="head_swivel" type="continuous"> <parent link="base_link"/> <child link="head"/> <axis xyz="0 0 1"/> <origin xyz="0 0 0.3"/> </joint>