关于go2和go2w的一点疑问

[AgentOfLyra]

<?xml version='1.0' encoding='utf-8'?>
<robot name="b2_description">
  <link name="base_link">
    <inertial>
      <origin xyz="0.000458 0.005261 0.000665" rpy="0 0 0" />
      <mass value="35.86" />
      <inertia ixx="0.27466" ixy="-0.000622" ixz="0.00315" iyy="1.0618" iyz="-0.00139" izz="1.1825" />
    </inertial>
    <visual>
      <origin xyz="0 0 0" rpy="0 0 0" />
      <geometry>
        <mesh filename="package://b2_description/meshes/base_link.dae" />
      </geometry>
      <material name="磨砂铝合金_011-effect"><color rgba="0.74876 0.74876 0.74876 1" /></material><material name="logo_001-effect"><color rgba="1 1 1 1" /></material><material name="材质_023-effect"><color rgba="0 0 0 1" /></material><material name="材质_024-effect"><color rgba="0.002853 0.002853 0.002853 1" /></material></visual>
    <collision>
      <origin xyz="0 0 0" rpy="0 0 0" />
        <geometry>
          <box size="0.5 0.28 0.15" />
        </geometry>
    </collision>
  </link>
......

可以看到像b2、b2w定义的是base link，它们的gazebo.launch也是这么定义的：

<launch>
  <include
    file="$(find gazebo_ros)/launch/empty_world.launch" />
  <node
    name="tf_footprint_base"
    pkg="tf"
    type="static_transform_publisher"
    args="0 0 0 0 0 0 base_link base_footprint 40" />
  <node
    name="spawn_model"
    pkg="gazebo_ros"
    type="spawn_model"
    args="-file $(find b2w_description)/urdf/b2w_description.urdf -urdf -model b2w_description"
    output="screen" />
  <node
    name="fake_joint_calibration"
    pkg="rostopic"
    type="rostopic"
    args="pub /calibrated std_msgs/Bool true" />
</launch>

这里发布了一个静态tf，我的疑问是这样的：
为什么在go1、go2、go2w当中，它们定义的都是base，然后在rviz里面fixed frame的配置也用的base，这没问题，

<!-- 节选自go2w -->
<robot name="go2w_description">
  <link name="base">
    <inertial>
      <origin xyz="0.021112 0 -0.005366" rpy="0 0 0" />
      <mass value="6.921" />
      <inertia ixx="0.02448" ixy="0.00012166" ixz="0.0014849" iyy="0.098077" iyz="-3.12E-05" izz="0.107" />
    </inertial>
    <visual>
      <origin xyz="0 0 0" rpy="0 0 0" />
      <geometry>
        <mesh filename="package://go2w_description/dae/base.dae" />
      </geometry>
      <material name="深色橡胶_001-effect"><color rgba="0.6717055 0.6924257 0.7742702 1" /></material><material name="白色logo_001-effect"><color rgba="1 1 1 1" /></material><material name="黑色贴纸_007-effect"><color rgba="0.009018 0.009018 0.009018 1" /></material><material name="黑色金属_007-effect"><color rgba="0.01341 0.01341 0.01341 1" /></material><material name="黑色塑料_003-effect"><color rgba="0.023455 0.023455 0.023455 1" /></material></visual>
    <collision>
      <origin rpy="0 0 0" xyz="0 0 0" />
      <geometry>
        <box size="0.3762 0.0935 0.114" />
      </geometry>
    </collision>
  </link>

 Global Options:
    Background Color: 238; 238; 236
    Default Light: true
    Fixed Frame: base
    Frame Rate: 30
  Name: root

但是在它们这几个狗兄弟的gazebo.launch里面，还是用的base_link发布的静态tf：

<launch>
  <include
    file="$(find gazebo_ros)/launch/empty_world.launch" />
  <node
    name="tf_footprint_base"
    pkg="tf"
    type="static_transform_publisher"
    args="0 0 0 0 0 0 base_link base_footprint 40" />
  <node
    name="spawn_model"
    pkg="gazebo_ros"
    type="spawn_model"
    args="-file $(find go2w_description)/urdf/go2w_description.urdf -urdf -model go2w_description"
    output="screen" />
  <node
    name="fake_joint_calibration"
    pkg="rostopic"
    type="rostopic"
    args="pub /calibrated std_msgs/Bool true" />
</launch>