gazbo中仿真小车与控制小车运动
本节根据书中第7章内容做简单修改而来，涉及文件较多，可以去下面的链接下下载
小车模型搭建
同前一篇创建一个新的ros包，在新的gzb_carbot包中练习
cd testCarBot/src;catkin_create_pkg gzb_carbot
cd myCar;mkdir launch;mkdir urdf
在urdf目录中分别创建下面几个文件，gzb_carbot.xacro robot.gazebo robot.world hokuyo.dae
小车模型描述文件 gzb_carbot.xacro
xacro 相比urdf文件做了一定的简化处理，类似于C语言中的宏功能。 该文件引用了另外两个文件robot.gazebo，hokuyo.dae；
gazbo中的仿真与上一章的区别在于，模型中需要增加 惯性质量与冲突检测相关的描述，多了相机与激光探测器模块
<?xml version="1.0"?>
<robot xmlns:xacro="http://www.ros.org/wiki/xacro"
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" name="robot1_xacro">
<xacro:property name="length_wheel" value="0.05" />
<xacro:property name="radius_wheel" value="0.05" />
<xacro:property name="camera_link" value="0.05" />
<xacro:macro name="default_inertial" params="mass">
<inertial>
<mass value="${mass}" />
<inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0" />
</inertial>
</xacro:macro>
<link name="base_footprint">
<visual>
<geometry>
<box size="0.001 0.001 0.001" />
</geometry>
<origin rpy="0 0 0" xyz="0 0 0" />
</visual>
<xacro:default_inertial mass="0.0001" />
</link>
<xacro:include filename="$(find gzb_carbot)/urdf/robot.gazebo" />
<gazebo reference="base_footprint">
<material>Gazebo/Green</material>
<turnGravityOff>false</turnGravityOff>
</gazebo>
<joint name="base_footprint_joint" type="fixed">
<origin xyz="0 0 0" />
<parent link="base_footprint" />
<child link="base_link" />
</joint>
<link name="base_link">
<visual>
<geometry>
<box size="0.2 .3 .1" />
</geometry>
<origin rpy="0 0 1.54" xyz="0 0 0.05" />
<material name="white">
<color rgba="1 1 1 1" />
</material>
</visual>
<collision>
<geometry>
<box size="0.2 .3 0.1" />
</geometry>
</collision>
<xacro:default_inertial mass="10" />
</link>
<link name="wheel_1">
<visual>
<geometry>
<cylinder length="${length_wheel}" radius="${radius_wheel}" />
</geometry>
<!-- <origin rpy="0 1.5 0" xyz="0.1 0.1 0"/> -->
<origin rpy="0 0 0" xyz="0 0 0" />
<material name="black">
<color rgba="0 0 0 1" />
</material>
</visual>
<collision>
<geometry>
<cylinder length="${length_wheel}" radius="${radius_wheel}" />
</geometry>
</collision>
<xacro:default_inertial mass="1" />
</link>
<link name="wheel_2">
<visual>
<geometry>
<cylinder length="${length_wheel}" radius="${radius_wheel}" />
</geometry>
<!-- <origin rpy="0 1.5 0" xyz="-0.1 0.1 0"/> -->
<origin rpy="0 0 0" xyz="0 0 0" />
<material name="black" />
</visual>
<collision>
<geometry>
<cylinder length="${length_wheel}" radius="${radius_wheel}" />
</geometry>
</collision>
<xacro:default_inertial mass="1" />
</link>
<link name="wheel_3">
<visual>
<geometry>
<cylinder length="${length_wheel}" radius="${radius_wheel}" />
</geometry>
<!-- <origin rpy="0 1.5 0" xyz="0.1 -0.1 0"/> -->
<origin rpy="0 0 0" xyz="0 0 0" />
<material name="black" />
</visual>
<collision>
<geometry>
<cylinder length="${length_wheel}" radius="${radius_wheel}" />
</geometry>
</collision>
<xacro:default_inertial mass="1" />
</link>
<link name="wheel_4">
<visual>
<geometry>
<cylinder length="${length_wheel}" radius="${radius_wheel}" />
</geometry>
<!-- <origin rpy="0 1.5 0" xyz="-0.1 -0.1 0"/> -->
<origin rpy="0 0 0" xyz="0 0 0" />
<material name="black" />
</visual>
<collision>
<geometry>
<cylinder length="${length_wheel}" radius="${radius_wheel}" />
</geometry>
</collision>
<xacro:default_inertial mass="1" />
</link>
<joint name="base_to_wheel1" type="continuous">
<parent link="base_link" />
<child link="wheel_1" />
<origin rpy="1.5707 0 0" xyz="0.1 0.15 0" />
<axis xyz="0 0 1" />
</joint>
<joint name="base_to_wheel2" type="continuous">
<axis xyz="0 0 1" />
<anchor xyz="0 0 0" />
<limit effort="100" velocity="100" />
<parent link="base_link" />
<child link="wheel_2" />
<origin rpy="1.5707 0 0" xyz="-0.1 0.15 0" />
</joint>
<joint name="base_to_wheel3" type="continuous">
<parent link="base_link" />
<axis xyz="0 0 1" />
<child link="wheel_3" />
<origin rpy="1.5707 0 0" xyz="0.1 -0.15 0" />
</joint>
<joint name="base_to_wheel4" type="continuous">
<parent link="base_link" />
<axis xyz="0 0 1" />
<child link="wheel_4" />
<origin rpy="1.5707 0 0" xyz="-0.1 -0.15 0" />
</joint>
<joint name="camera_joint" type="fixed">
<axis xyz="0 1 0" />
<origin xyz="0.125 0 0.125" rpy="0 0 0" />
<parent link="base_link" />
<child link="camera_link" />
</joint>
<!-- Camera -->
<link name="camera_link">
<collision>
<origin xyz="0 0 0" rpy="0 0 0" />
<geometry>
<box size="0.05 0.05 0.05" />
</geometry>
</collision>
<visual>
<origin xyz="0 0 0" rpy="0 0 0" />
<geometry>
<box size="0.05 0.05 0.05" />
</geometry>
<material name="red">
<color rgba="1 0 0 1" />
</material>
</visual>
<inertial>
<mass value="1e-5" />
<origin xyz="0 0 0" rpy="0 0 0" />
<inertia ixx="1e-6" ixy="0" ixz="0" iyy="1e-6" iyz="0" izz="1e-6" />
</inertial>
</link>
<joint name="hokuyo_joint" type="fixed">
<axis xyz="0 1 0" />
<origin xyz="0.125 0.05 0.125" rpy="0 0 0" />
<parent link="base_link" />
<child link="hokuyo_link" />
</joint>
<!-- Hokuyo Laser -->
<link name="hokuyo_link">
<collision>
<origin xyz="0 0 0" rpy="0 0 0" />
<geometry>
<box size="0.1 0.1 0.1" />
</geometry>
</collision>
<visual>
<origin xyz="0 0 0" rpy="0 0 0" />
<geometry>
<mesh filename="package://gzb_carbot/urdf/hokuyo.dae" />
</geometry>
</visual>
<inertial>
<mass value="1e-5" />
<origin xyz="0 0 0" rpy="0 0 0" />
<inertia ixx="1e-6" ixy="0" ixz="0" iyy="1e-6" iyz="0" izz="1e-6" />
</inertial>
</link>
</robot>
hokuyo.dae 激光探测器模型文件，文件过大，省去，可以去链接中下载
robot.gazebo 机器人在gazbo中仿真的必要描述
<?xml version="1.0"?>
<robot>
<!-- materials -->
<gazebo reference="base_link">
<material>Gazebo/Orange</material>
</gazebo>
<gazebo reference="wheel_1">
<material>Gazebo/Black</material>
</gazebo>
<gazebo reference="wheel_2">
<material>Gazebo/Black</material>
</gazebo>
<gazebo reference="wheel_3">
<material>Gazebo/Black</material>
</gazebo>
<gazebo reference="wheel_4">
<material>Gazebo/Black</material>
</gazebo>
<!-- ros_control plugin -->
<gazebo>
<plugin name="gazebo_ros_control" filename="libgazebo_ros_control.so">
<robotNamespace>/robot</robotNamespace>
</plugin>
</gazebo>
<!-- Link1 -->
<gazebo reference="link1">
<material>Gazebo/Orange</material>
</gazebo>
<!-- Link2 -->
<gazebo reference="link2">
<mu1>0.2</mu1>
<mu2>0.2</mu2>
<material>Gazebo/Black</material>
</gazebo>
<!-- Link3 -->
<gazebo reference="link3">
<mu1>0.2</mu1>
<mu2>0.2</mu2>
<material>Gazebo/Orange</material>
</gazebo>
<!-- camera_link -->
<gazebo reference="camera_link">
<mu1>0.2</mu1>
<mu2>0.2</mu2>
<material>Gazebo/Red</material>
</gazebo>
<!-- hokuyo -->
<gazebo reference="hokuyo_link">
<sensor type="ray" name="head_hokuyo_sensor">
<pose>0 0 0 0 0 0</pose>
<visualize>false</visualize>
<update_rate>40</update_rate>
<ray>
<scan>
<horizontal>
<samples>720</samples>
<resolution>1</resolution>
<min_angle>-1.570796</min_angle>
<max_angle>1.570796</max_angle>
</horizontal>
</scan>
<range>
<min>0.10</min>
<max>30.0</max>
<resolution>0.01</resolution>
</range>
<noise>
<type>gaussian</type>
<!-- Noise parameters based on published spec for Hokuyo laser
achieving "+-30mm" accuracy at range < 10m. A mean of 0.0m and
stddev of 0.01m will put 99.7% of samples within 0.03m of the true
reading. -->
<mean>0.0</mean>
<stddev>0.01</stddev>
</noise>
</ray>
<plugin name="gazebo_ros_head_hokuyo_controller" filename="libgazebo_ros_laser.so">
<topicName>/robot/laser/scan</topicName>
<frameName>hokuyo_link</frameName>
</plugin>
</sensor>
</gazebo>
<!-- camera -->
<gazebo reference="camera_link">
<sensor type="camera" name="camera1">
<update_rate>30.0</update_rate>
<camera name="head">
<horizontal_fov>1.3962634</horizontal_fov>
<image>
<width>800</width>
<height>800</height>
<format>R8G8B8</format>
</image>
<clip>
<near>0.02</near>
<far>300</far>
</clip>
<noise>
<type>gaussian</type>
<!-- Noise is sampled independently per pixel on each frame.
That pixel's noise value is added to each of its color
channels, which at that point lie in the range [0,1]. -->
<mean>0.0</mean>
<stddev>0.007</stddev>
</noise>
</camera>
<plugin name="camera_controller" filename="libgazebo_ros_camera.so">
<alwaysOn>true</alwaysOn>
<updateRate>0.0</updateRate>
<cameraName>robot/camera1</cameraName>
<imageTopicName>image_raw</imageTopicName>
<cameraInfoTopicName>camera_info</cameraInfoTopicName>
<frameName>camera_link</frameName>
<hackBaseline>0.07</hackBaseline>
<distortionK1>0.0</distortionK1>
<distortionK2>0.0</distortionK2>
<distortionK3>0.0</distortionK3>
<distortionT1>0.0</distortionT1>
<distortionT2>0.0</distortionT2>
</plugin>
</sensor>
</gazebo>
</robot>
仿真启动文件
launch目录中创建 carbot.launch文件，内容如下
在gazbo中仿真显示 必须先有world模型才可以正常显示
<?xml version="1.0"?>
<launch>
<!-- these are the arguments you can pass this launch file, for example paused:=true -->
<arg name="paused" default="true"/>
<arg name="use_sim_time" default="false"/>
<arg name="gui" default="true"/>
<arg name="headless" default="false"/>
<arg name="debug" default="true"/>
<!-- We resume the logic in empty_world.launch, changing only the name of the world to be launched -->
<include file="$(find gazebo_ros)/launch/empty_world.launch">
<arg name="debug" value="$(arg debug)" />
<arg name="gui" value="$(arg gui)" />
<arg name="paused" value="$(arg paused)"/>
<arg name="use_sim_time" value="$(arg use_sim_time)"/>
<arg name="headless" value="$(arg headless)"/>
</include>
<!-- Load the URDF into the ROS Parameter Server -->
<arg name="model" />
<param name="robot_description"
command="$(find xacro)/xacro.py $(arg model)" />
<!-- Run a python script to the send a service call to gazebo_ros to spawn a URDF robot -->
<node name="urdf_spawner" pkg="gazebo_ros" type="spawn_model" respawn="false" output="screen"
args="-urdf -model robot1 -param robot_description -z 0.05"/>
</launch>
去工作空间根目录，执行catkin_make，生成包后，执行以下命令即可看到gazbo中仿真结果
roslaunch gzb_carbot carbot.launch model:="`rospack find gzb_carbot`/urdf/gzb_carbot.xacro"
image.png
运动控制
待更新
