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