4 使用smartcar进行仿真

博客转自古-月：http://blog.csdn.net/hcx25909

之前的博客中，我们使用rviz进行了TurtleBot的仿真，而且使用urdf文件建立了自己的机器人smartcar，本篇博客是将两者进行结合，使用smartcar机器人在rviz中进行仿真。

一、模型完善

之前我们使用的都是urdf文件格式的模型，在很多情况下，ROS对urdf文件的支持并不是很好，使用宏定义的.xacro文件兼容性更好，扩展性也更好。所以我们把之前的urdf文件重新整理编写成.xacro文件。.xacro文件主要分为三部分：

1、机器人主体

<?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属性部分

<?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、主文件

<?xml version="1.0"?>
 
<robot name="smartcar"  
    xmlns:xi="http://www.w3.org/2001/XInclude"
	xmlns:gazebo="http://playerstage.sourceforge.net/gazebo/xmlschema/#gz"
    xmlns:model="http://playerstage.sourceforge.net/gazebo/xmlschema/#model"
	xmlns:sensor="http://playerstage.sourceforge.net/gazebo/xmlschema/#sensor"
	xmlns:body="http://playerstage.sourceforge.net/gazebo/xmlschema/#body"
    xmlns:geom="http://playerstage.sourceforge.net/gazebo/xmlschema/#geom"
    xmlns:joint="http://playerstage.sourceforge.net/gazebo/xmlschema/#joint"
	xmlns:controller="http://playerstage.sourceforge.net/gazebo/xmlschema/#controller"
	xmlns:interface="http://playerstage.sourceforge.net/gazebo/xmlschema/#interface"
	xmlns:rendering="http://playerstage.sourceforge.net/gazebo/xmlschema/#rendering"
    xmlns:renderable="http://playerstage.sourceforge.net/gazebo/xmlschema/#renderable"
    xmlns:physics="http://playerstage.sourceforge.net/gazebo/xmlschema/#physics"
	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/>
 
  <smartcar_sim/>
 
</robot>

二、lanuch文件

在launch文件中要启动节点和模拟器。

<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>

古月的源代码可在此处找到：http://download.csdn.net/detail/hcx25909/5487985，不过他的代码是针对Fuerte版本，所以配置文件要做一些修改，包括如下内容

1. urdf.vcg修改为urdf.rviz

2. <node name="arbotix" pkg="arbotix_python" type="driver.py" output="screen">
   #改为
   <node name="arbotix" pkg="arbotix_python" type="arbotix_driver" output="screen"

3. lauch和urdf文件夹内的配置文件名字由urdf.vcg改为urdf.rviz

三、仿真测试

首先运行lanuch，既可以看到rviz中的机器人：

roslaunch smartcar_description smartcar_display.rviz.launch

 发布一条动作的消息。

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、节点关系

rosrun rqt_graph rqt_graph

Nodes/Topics