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

<?xml version="1.0"?><robot>  <!-- Put all the color definitions in a separate file -->  <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

<?xml version="1.0"?><robot name="base" xmlns:xacro="http://ros.org/wiki/xacro">  <!-- Define a number of dimensions using properties -->  <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" />  <!-- define a wheel -->  <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}_${suffix}_wheel_link"><!-- <visual><origin xyz=" 0 0 0 " rpy="0 0 0" />      <geometry>        <mesh          filename="package://common/urdf/meshes/wheel.STL" />      </geometry>      <material name="${color}" /></visual>-->      <visual>        <origin xyz="0 0 0" rpy="0 0 0" />        <geometry>          <cylinder radius="${wheel_radius}" length="${wheel_length}"/>        </geometry>        <material name="${color}" />      </visual>    </link>  </macro>  <!-- The base xacro macro -->  <macro name="base" params="name color">    <link name="${name}_link"><!-- <visual><origin xyz=" 0 0 0 " rpy="0 0 0" />      <geometry>        <mesh          filename="package://common/urdf/meshes/dash_base_all.STL" />      </geometry>      <material name="">                <color          rgba="255 215 0 0.5"/>      </material></visual>-->        <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>   <!-- Add the drive wheels -->   <wheel parent="base" suffix="l" reflect="1" color="Orange"/>   <wheel parent="base" suffix="r" reflect="-1" color="Orange"/></robot>

• 整体: dashbase.urdf

<?xml version="1.0"?><robot name="box_robot" xmlns:xacro="http://ros.org/wiki/xacro">   <!-- Include all component files -->   <xacro:include filename="$(find dash_describe)/urdf/dashbase/materials.urdf.xacro" />   <xacro:include filename="$(find dash_describe)/urdf/dashbase/base.urdf.xacro" />   <!-- Add the base and wheels -->   <base name="base" color="Black"/></robot>

launch

创建 launch/dash_describe.launch,内容如下：

<launch>    <!-- Load the URDF/Xacro model of our robot -->    <arg name="urdf_file" default="$(find xacro)/xacro.py '$(find dash_describe)/urdf/dashbase/dashbase.xacro'" />    <param name="robot_description" command="$(arg urdf_file)" />    <!-- Publish the robot state -->    <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