瞬驰(Dash)D1开发手册--URDF

创建URDF文件，就可以在rviz中实时观测底盘的移动。

创建包

cd ~/catkin_ws/src
catkin_create_pkg dash_describe std_msgs rospy roscpp

urdf文件

在urdf/dashbase目录下需要创建如下文件：

• materials.urdf.xacro 颜色属性

<robot>

  

  <material name="Black">
    <color rgba="0.2 0.2 0.2 1.0"/>
  material>

   <material name="TransparentBlack">
    <color rgba="0.2 0.2 0.2 0.8"/>
  material>

  <material name="Orange">
    <color rgba="1.0  0.55 0.0 1.0"/>
  material>

  <material name="Grey">
    <color rgba="0.7 0.7 0.7 1.0"/>
  material>

  <material name="DarkGrey">
    <color rgba="0.3 0.3 0.3 1.0"/>
  material>

  <material name="Red">
    <color rgba="0.8 0.0 0.0 1.0"/>
  material>

  <material name="White">
    <color rgba="1.0 1.0 1.0 1.0"/>
  material>

  <material name="OffWhite">
    <color rgba="0.8 0.8 0.8 1.0"/>
  material>

  <material name="Blue">
    <color rgba="0.0 0.0 0.8 1.0"/>
  material>

  <material name="Green">
    <color rgba="0.0 0.8 0.0 1.0"/>
  material>

  <material name="TransparentGreen">
    <color rgba="0.0 0.8 0.0 0.5"/>
  material>

robot>

• 底盘和轮子的定义 base.urdf.xacro

<robot name="base" xmlns:xacro="http://ros.org/wiki/xacro">

  
  <property name="base_length" value="0.165" />
  <property name="base_radius" value="0.20" />
  <property name="wheel_length" value="0.02" />
  <property name="wheel_radius" value="0.060" />
  <property name="wheel_offset_x" value="0" />
  <property name="wheel_offset_y" value="0.17" />
  <property name="wheel_offset_z" value="-0.038" />

  <property name="PI" value="3.1415926" />

  
  <macro name="wheel" params="suffix parent reflect color">
    <joint name="${parent}_${suffix}_wheel_joint" type="continuous">
      <axis xyz="0 0 1" />
      <limit effort="100" velocity="100"/>
      <safety_controller k_velocity="10" />
      <origin xyz="${wheel_offset_x} ${reflect*wheel_offset_y} ${wheel_offset_z}" rpy="${reflect*PI/2} 0 0" />
      <parent link="${parent}_link"/>
      <child link="${parent}_${suffix}_wheel_link"/>
    joint>
    <link name="${parent}_${suffix}_wheel_link">

      <visual>
        <origin xyz="0 0 0" rpy="0 0 0" />
        <geometry>
          <cylinder radius="${wheel_radius}" length="${wheel_length}"/>
        geometry>
        <material name="${color}" />
      visual>
    link>
  macro>

  
  <macro name="base" params="name color">
    <link name="${name}_link">

        <visual>
            <origin xyz="0 0 0" rpy="0 0 0"/>
            <geometry>
                <cylinder length="${base_length}" radius="${base_radius}"/>
            geometry>
            <material name="iRobot/LightGrey"/>
        visual>
        <collision>
            <origin xyz="0 0 0" rpy="0 0 0"/>
            <geometry>
                <cylinder length="${base_length}" radius="${base_radius}"/>
            geometry>
        collision>
    link>
  macro>

  <link name="base_footprint">
      <visual>
        <origin xyz="0 0 0" rpy="0 0 0" />
        <geometry>
          <box size="0.05 0.05 0.001" />
        geometry>
        <material name="TransparentGreen" />
      visual>
  link>

  <joint name="base_joint" type="fixed">
    <origin xyz="0 0 ${base_length/2 - wheel_offset_z}" rpy="0 0 0" />      
    <parent link="base_footprint"/>
    <child link="base_link" />
  joint>

   
   <wheel parent="base" suffix="l" reflect="1" color="Orange"/>
   <wheel parent="base" suffix="r" reflect="-1" color="Orange"/>

robot>

• 整体: dashbase.urdf

<robot name="box_robot" xmlns:xacro="http://ros.org/wiki/xacro">
   
   <xacro:include filename="$(find dash_describe)/urdf/dashbase/materials.urdf.xacro" />
   <xacro:include filename="$(find dash_describe)/urdf/dashbase/base.urdf.xacro" />
   
   <base name="base" color="Black"/>

robot>

launch

创建 launch/dash_describe.launch,内容如下：

<launch>
    
    <arg name="urdf_file" default="$(find xacro)/xacro.py '$(find dash_describe)/urdf/dashbase/dashbase.xacro'" />

    <param name="robot_description" command="$(arg urdf_file)" />

    
    <node name="robot_state_publisher" pkg="robot_state_publisher" type="state_publisher">
        <param name="publish_frequency" value="20.0"/>
    node>

    <node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher">
        <param name="rate" value="20.0"/>
    node>
launch>

启动命令

在一个终端执行

roslaunch dash_describe dash_describe.launch

在另一个终端执行

rviz

在rviz界面， Global Options->Fixed Color 选择”base_footprint”, 点击左下部”Add”按钮，选择”RobotModel“。
然后就可以看到我们创建的小车底盘了。

注意：如果在raspberry Pi下运行， rviz运行不了。

raspberry pi运行方法

需要raspberry pi和电脑配合使用。首先在/etc/hosts中相互添加对方的hostname和ip

然后， 在raspberry Pi执行如下语句

roslaunch dash_describe dash_describe.launch

在电脑的同一个终端先后执行如下命令。

export ROS_MASTER_URI=http://RaspberryPi的ip:11311

然后执行rviz