[置頂] ROS探索總結（六）——使用smartcar進行模擬

        之前的部落格中，我們使用rviz進行了TurtleBot的模擬，而且使用urdf檔案建立了自己的機器人smartcar，本篇部落格是將兩者進行結合，使用smartcar機器人在rviz中進行模擬。

一、模型完善         之前我們使用的都是urdf檔案格式的模型，在很多情況下，ROS對urdf檔案的支援並不是很好，使用宏定義的.xacro檔案相容性更好，擴充性也更好。所以我們把之前的urdf檔案重新整理編寫成.xacro檔案。
        .xacro檔案主要分為三部分：
1、機器人主體

<?xml version="1.0"?><robot name="smartcar" xmlns:xacro="http://ros.org/wiki/xacro">  <property name="M_PI" value="3.14159"/>  <!-- Macro for SmartCar body. Including Gazebo extensions, but does not include Kinect -->  <include filename="$(find smartcar_description)/urdf/gazebo.urdf.xacro"/>  <property name="base_x" value="0.33" />  <property name="base_y" value="0.33" />  <xacro:macro name="smartcar_body"><link name="base_link"><inertial>      <origin xyz="0 0 0.055"/>      <mass value="1.0" />      <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>    </inertial>    <visual>      <geometry>        <box size="0.25 .16 .05"/>      </geometry>  <origin rpy="0 0 0" xyz="0 0 0.055"/>      <material name="blue">  <color rgba="0 0 .8 1"/>      </material>   </visual>   <collision>      <origin rpy="0 0 0" xyz="0 0 0.055"/>      <geometry>        <box size="0.25 .16 .05" />      </geometry>    </collision>  </link> <link name="left_front_wheel"><inertial>      <origin  xyz="0.08 0.08 0.025"/>      <mass value="0.1" />       <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>    </inertial>    <visual>      <geometry>        <cylinder length=".02" radius="0.025"/>      </geometry>      <material name="black">        <color rgba="0 0 0 1"/>      </material>    </visual>    <collision>      <origin rpy="0 1.57075 1.57075" xyz="0.08 0.08 0.025"/>      <geometry>         <cylinder length=".02" radius="0.025"/>      </geometry>    </collision>  </link>  <joint name="left_front_wheel_joint" type="continuous">    <axis xyz="0 0 1"/>    <parent link="base_link"/>    <child link="left_front_wheel"/>    <origin rpy="0 1.57075 1.57075" xyz="0.08 0.08 0.025"/>    <limit effort="100" velocity="100"/>    <joint_properties damping="0.0" friction="0.0"/>  </joint>  <link name="right_front_wheel"><inertial>      <origin xyz="0.08 -0.08 0.025"/>      <mass value="0.1" />       <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>    </inertial>    <visual>      <geometry>        <cylinder length=".02" radius="0.025"/>      </geometry>      <material name="black">        <color rgba="0 0 0 1"/>      </material>    </visual>    <collision>      <origin rpy="0 1.57075 1.57075" xyz="0.08 -0.08 0.025"/>      <geometry>         <cylinder length=".02" radius="0.025"/>      </geometry>    </collision>  </link>  <joint name="right_front_wheel_joint" type="continuous">    <axis xyz="0 0 1"/>    <parent link="base_link"/>    <child link="right_front_wheel"/>    <origin rpy="0 1.57075 1.57075" xyz="0.08 -0.08 0.025"/>    <limit effort="100" velocity="100"/>    <joint_properties damping="0.0" friction="0.0"/> </joint> <link name="left_back_wheel">    <inertial>      <origin xyz="-0.08 0.08 0.025"/>      <mass value="0.1" />       <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>    </inertial>    <visual>      <geometry>        <cylinder length=".02" radius="0.025"/>      </geometry>      <material name="black">        <color rgba="0 0 0 1"/>      </material>   </visual>   <collision>       <origin rpy="0 1.57075 1.57075" xyz="-0.08 0.08 0.025"/>      <geometry>         <cylinder length=".02" radius="0.025"/>      </geometry>    </collision>  </link>  <joint name="left_back_wheel_joint" type="continuous">    <axis xyz="0 0 1"/>    <parent link="base_link"/>    <child link="left_back_wheel"/>    <origin rpy="0 1.57075 1.57075" xyz="-0.08 0.08 0.025"/>    <limit effort="100" velocity="100"/>    <joint_properties damping="0.0" friction="0.0"/>  </joint>  <link name="right_back_wheel"><inertial>       <origin xyz="-0.08 -0.08 0.025"/>       <mass value="0.1" />       <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>    </inertial>    <visual>      <geometry>        <cylinder length=".02" radius="0.025"/>      </geometry>      <material name="black">        <color rgba="0 0 0 1"/>      </material>   </visual>   <collision>      <origin rpy="0 1.57075 1.57075" xyz="-0.08 -0.08 0.025"/>      <geometry>         <cylinder length=".02" radius="0.025"/>      </geometry>    </collision>  </link>  <joint name="right_back_wheel_joint" type="continuous">    <axis xyz="0 0 1"/>    <parent link="base_link"/>    <child link="right_back_wheel"/>    <origin rpy="0 1.57075 1.57075" xyz="-0.08 -0.08 0.025"/>    <limit effort="100" velocity="100"/>    <joint_properties damping="0.0" friction="0.0"/>  </joint>  <link name="head"><inertial>      <origin xyz="0.08 0 0.08"/>      <mass value="0.1" />      <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>    </inertial>    <visual>      <geometry>        <box size=".02 .03 .03"/>      </geometry>  <material name="white"><color rgba="1 1 1 1"/>  </material>     </visual>     <collision>      <origin xyz="0.08 0 0.08"/>      <geometry>         <cylinder length=".02" radius="0.025"/>      </geometry>    </collision>  </link>  <joint name="tobox" type="fixed">    <parent link="base_link"/>    <child link="head"/>    <origin xyz="0.08 0 0.08"/>  </joint>  </xacro:macro></robot>

2、gazebo屬性部分

<?xml version="1.0"?><robot xmlns:controller="http://playerstage.sourceforge.net/gazebo/xmlschema/#controller" xmlns:interface="http://playerstage.sourceforge.net/gazebo/xmlschema/#interface" xmlns:sensor="http://playerstage.sourceforge.net/gazebo/xmlschema/#sensor" xmlns:xacro="http://ros.org/wiki/xacro" name="smartcar_gazebo"><!-- ASUS Xtion PRO camera for simulation --><!-- gazebo_ros_wge100 plugin is in kt2_gazebo_plugins package --><xacro:macro name="smartcar_sim">    <gazebo reference="base_link">        <material>Gazebo/Blue</material>    </gazebo>    <gazebo reference="right_front_wheel">        <material>Gazebo/FlatBlack</material></gazebo><gazebo reference="right_back_wheel">        <material>Gazebo/FlatBlack</material>    </gazebo>    <gazebo reference="left_front_wheel">        <material>Gazebo/FlatBlack</material>    </gazebo>    <gazebo reference="left_back_wheel">        <material>Gazebo/FlatBlack</material>    </gazebo>    <gazebo reference="head">        <material>Gazebo/White</material>    </gazebo></xacro:macro></robot>

3、主檔案

<?xml version="1.0"?><robot name="turtlebot"         xmlns:sensor="http://playerstage.sourceforge.net/gazebo/xmlschema/#sensor"       xmlns:controller="http://playerstage.sourceforge.net/gazebo/xmlschema/#controller"       xmlns:interface="http://playerstage.sourceforge.net/gazebo/xmlschema/#interface"   xmlns:xacro="http://ros.org/wiki/xacro">  <include filename="$(find smartcar_description)/urdf/smartcar_body.urdf.xacro" />  <!-- Body of SmartCar, with plates, standoffs and Create (including sim sensors) -->  <smartcar_body/></robot>

二、lanuch檔案

        在launch檔案中要啟動節點和模擬器。

<launch>    <param name="/use_sim_time" value="false" /><!-- Load the URDF/Xacro model of our robot -->    <arg name="urdf_file" default="$(find xacro)/xacro.py '$(find smartcar_description)/urdf/smartcar.urdf.xacro'" /><arg name="gui" default="false" /><param name="robot_description" command="$(arg urdf_file)" /><param name="use_gui" value="$(arg gui)"/><node name="arbotix" pkg="arbotix_python" type="driver.py" output="screen">        <rosparam file="$(find smartcar_description)/config/smartcar_arbotix.yaml" command="load" />        <param name="sim" value="true"/>    </node><node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher" ></node>    <node name="robot_state_publisher" pkg="robot_state_publisher" type="state_publisher">        <param name="publish_frequency" type="double" value="20.0" />    </node> <!-- We need a static transforms for the wheels -->    <node pkg="tf" type="static_transform_publisher" name="odom_left_wheel_broadcaster" args="0 0 0 0 0 0 /base_link /left_front_link 100" />    <node pkg="tf" type="static_transform_publisher" name="odom_right_wheel_broadcaster" args="0 0 0 0 0 0 /base_link /right_front_link 100" /><node name="rviz" pkg="rviz" type="rviz" args="-d $(find smartcar_description)/urdf.vcg" /></launch>

三、模擬測試

        首先運行lanuch，既可以看到rviz中的機器人：

roslaunch smartcar_display.rviz.launch

        
         發布一條動作的訊息。

rostopic pub -r 10 /cmd_vel geometry_msgs/Twist '{linear: {x: 0.5, y: 0, z: 0}, angular: {x: 0, y: 0, z: 0.5}}'

四、節點關係