1. 前言
本文旨在实现摄像头在gazebo的仿真
实现具体流程为：
照相机在rviz的显示——>添加摄像头在gazebo的外观属性——>添加gazebo提供的摄像头插件
2. 照相机在rviz的简单示意
创建名为usb_camera.xacro的文件，用于表示摄像头本体
关于xacro文件的具体含义，可以浏览该文章：ROS——xacro文件解读
<?xml version="1.0"?>
<robot name="usb_camera" xmlns:xacro="http://www.ros.org/wiki/xacro" >
<!-- COLOR -->
<material name="Black">
<color rgba="0 0 0 1" />
</material>
<material name="White">
<color rgba="1 1 1 1" />
</material>
<!-- PROPERTY-->
<xacro:property name="mass" value="0.1" />
<xacro:macro name="usb_camera" >
<link name="base_link">
<inertial>
<mass value="${mass}" />
<origin xyz="0 0 0" />
<inertia ixx="0.01" ixy="0.0" ixz="0.0"
iyy="0.01" iyz="0.0"
izz="0.01" />
</inertial>
<visual>
<origin xyz="0 0 0" rpy="0 0 0" />
<geometry>
<box size="0.005 0.02 0.02" />
</geometry>
<material name="White"/>
</visual>
<collision>
<origin xyz="0.0 0.0 0.0" rpy="0 0 0" />
<geometry>
<box size="0.005 0.02 0.02" />
</geometry>
</collision>
</link>
<joint name="base_to_camera_joint" type="fixed">
<parent link="base_link"/>
<child link="usb_camera_link"/>
<origin xyz="0 0 0" rpy="0 0 0" />
</joint>
<link name="usb_camera_link">
<inertial>
<mass value="${mass}" />
<origin xyz="0 0 0" />
<inertia ixx="0.01" ixy="0.0" ixz="0.0"
iyy="0.01" iyz="0.0"
izz="0.01" />
</inertial>
<visual>
<origin xyz=" 0 0 0 " rpy="0 0 0" />
<geometry>
<box size="0.01 0.04 0.04" />
</geometry>
<material name="Black"/>
</visual>
<collision>
<origin xyz="0.0 0.0 0.0" rpy="0 0 0" />
<geometry>
<box size="0.01 0.04 0.04" />
</geometry>
</collision>
</link>
</xacro:macro>
</robot>
设置摄像头为box杆件，是最为简单的示意图
通过将不同模块（诸如摄像头，kinetic等）写成相应的xacro文件，并利用总xacro文件引用这些模块，方便后期进行机器人模块组装和修改
创建名为robot.xacro文件，其引用usb_camera.xacro文件：
<?xml version="1.0"?>
<robot name="robot" xmlns:xacro="http://www.ros.org/wiki/xacro">
<xacro:include filename="$(find 包名)/urdf/usb_camera.xacro" />
<usb_camera />
</robot>
创建名为display的launch文件加载robot.xacro。在本文即加载摄像头：
<?xml version = "1.0"?>
<launch>
<arg name = "model" default = "$(find xacro)/xacro --inorder '$(find 包名)/urdf/robot.xacro'" />
<arg name = "gui" default = "true" />
<param name = "robot_description" command = "$(arg model)" />
<param name = "use_gui" value = "$(arg gui)" />
<node name = "joint_state_publisher" pkg = "joint_state_publisher" type = "joint_state_publisher" />
<node name = "robot_state_publisher" pkg = "robot_state_publisher" type = "state_publisher" />
<node name = "rviz" pkg = "rviz" type = "rviz" args = "-d $(find urdf_tutorial)/urdf.rviz" />
</launch>
rivz显示的图像如下：
3. 为摄像头添加gazebo的外观属性
要让杆件在gazebo有外观属性，必须在xacro文件中添加gazebo的material标签
具体形式如下：
<gazebo reference="杆件名">
<material>Gazebo/颜色</material>
</gazebo>
因此，usb_camera.xacro文件修改为如下：
<?xml version="1.0"?>
<robot name="usb_camera" xmlns:xacro="http://www.ros.org/wiki/xacro" >
<!-- COLOR -->
<material name="Black">
<color rgba="0 0 0 1" />
</material>
<material name="White">
<color rgba="1 1 1 1" />
</material>
<!-- PROPERTY-->
<xacro:property name="mass" value="0.1" />
<xacro:macro name="usb_camera" >
<link name="base_link">
<inertial>
<mass value="${mass}" />
<origin xyz="0 0 0" />
<inertia ixx="0.01" ixy="0.0" ixz="0.0"
iyy="0.01" iyz="0.0"
izz="0.01" />
</inertial>
<visual>
<origin xyz="0 0 0" rpy="0 0 0" />
<geometry>
<box size="0.005 0.02 0.02" />
</geometry>
<material name="White"/>
</visual>
<collision>
<origin xyz="0.0 0.0 0.0" rpy="0 0 0" />
<geometry>
<box size="0.005 0.02 0.02" />
</geometry>
</collision>
</link>
<gazebo reference="base_link">
<material>Gazebo/White</material>
</gazebo>
<joint name="base_to_camera_joint" type="fixed">
<parent link="base_link"/>
<child link="usb_camera_link"/>
<origin xyz="0 0 0" rpy="0 0 0" />
</joint>
<link name="usb_camera_link">
<inertial>
<mass value="${mass}" />
<origin xyz="0 0 0" />
<inertia ixx="0.01" ixy="0.0" ixz="0.0"
iyy="0.01" iyz="0.0"
izz="0.01" />
</inertial>
<visual>
<origin xyz=" 0 0 0 " rpy="0 0 0" />
<geometry>
<box size="0.01 0.04 0.04" />
</geometry>
<material name="Black"/>
</visual>
<collision>
<origin xyz="0.0 0.0 0.0" rpy="0 0 0" />
<geometry>
<box size="0.01 0.04 0.04" />
</geometry>
</collision>
</link>
<gazebo reference="usb_camera_link">
<material>Gazebo/Black</material>
</gazebo>
</xacro:macro>
</robot>
上述所创建display.launch是在rviz中显示，为使摄像头能在gazebo显示，需修改对应内容，如下所示：
<launch>
<!-- 运行gazebo仿真环境 -->
<include file="$(find gazebo_ros)/launch/empty_world.launch" />
<!-- 加载机器人模型描述参数 -->
<param name="robot_description" command="$(find xacro)/xacro --inorder '$(find 包名)/urdf/robot.xacro'" />
<!-- 运行joint_state_publisher节点，发布机器人的关节状态 -->
<node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher" />
<!-- 运行robot_state_publisher节点，发布tf -->
<node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" />
<!-- 在gazebo中加载机器人模型-->
<node name="urdf_spawner" pkg="gazebo_ros" type="spawn_model" respawn="false" output="screen"
args="-urdf -model 机器人名 -param robot_description"/>
</launch>
gazebo显示的图像如下：
4. 为xacro文件添加摄像头插件
截至到目前为止，camera杆件只是一个示意图
gazebo提供了摄像头插件，能够使camera杆件进行摄像等功能
示例插件代码如下：
<gazebo reference="杆件名">
<sensor type="camera" name="camera_node">
<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>
<mean>0.0</mean>
<stddev>0.007</stddev>
</noise>
</camera>
<plugin name="gazebo_camera" filename="libgazebo_ros_camera.so">
<alwaysOn>true</alwaysOn>
<updateRate>0.0</updateRate>
<cameraName>/camera</cameraName>
<imageTopicName>image_raw</imageTopicName>
<cameraInfoTopicName>camera_info</cameraInfoTopicName>
<frameName>usb_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>
4.1 传感器的类型和名字
<sensor type="camera" name="****"> ... </sensor>
由于模拟摄像头，故类型为“camera”
“name”的名字必须是唯一
4.2 图片更新的最大频率
<update_rate>****</update_rate>
4.3 摄像头的具体配置
<horizontal_fov>****</horizontal_fov> <image> <width>****</width> <height>****</height> <format>****</format> </image> <clip> <near>****</near> <far>****</far> </clip>
4.4 链接到gazebo提供的摄像头插件
<plugin name="gazebo_camera" filename="libgazebo_ros_camera.so"> ... </plugin>
4.4.1 指定插件发布的话题名称
<cameraName>camera</cameraName> <imageTopicName>image_raw</imageTopicName> <cameraInfoTopicName>camera_info</cameraInfoTopicName>
指定/camera/image_raw是摄像头发布的图像主题话题名称
指定/camera/camera_info是摄像头发布的图像信息话题名称
（名称无强制要求，可修改）
4.4.2 为图像指定坐标系
<frameName>杆件名</frameName>
指定是基于哪个杆件坐标系发布的图像
因此，在usb_camera.xacro文件引用摄像头插件，修改得到：
<?xml version="1.0"?>
<robot name="usb_camera" xmlns:xacro="http://www.ros.org/wiki/xacro" >
<!-- COLOR -->
<material name="Black">
<color rgba="0 0 0 1" />
</material>
<material name="White">
<color rgba="1 1 1 1" />
</material>
<!-- PROPERTY-->
<xacro:property name="mass" value="0.1" />
<xacro:macro name="usb_camera" >
<link name="base_link">
<inertial>
<mass value="${mass}" />
<origin xyz="0 0 0" />
<inertia ixx="0.01" ixy="0.0" ixz="0.0"
iyy="0.01" iyz="0.0"
izz="0.01" />
</inertial>
<visual>
<origin xyz="0 0 0" rpy="0 0 0" />
<geometry>
<box size="0.005 0.02 0.02" />
</geometry>
<material name="White"/>
</visual>
<collision>
<origin xyz="0.0 0.0 0.0" rpy="0 0 0" />
<geometry>
<box size="0.005 0.02 0.02" />
</geometry>
</collision>
</link>
<gazebo reference="base_link">
<material>Gazebo/White</material>
</gazebo>
<joint name="base_to_camera_joint" type="fixed">
<parent link="base_link"/>
<child link="usb_camera_link"/>
<origin xyz="0 0 0" rpy="0 0 0" />
</joint>
<link name="usb_camera_link">
<inertial>
<mass value="${mass}" />
<origin xyz="0 0 0" />
<inertia ixx="0.01" ixy="0.0" ixz="0.0"
iyy="0.01" iyz="0.0"
izz="0.01" />
</inertial>
<visual>
<origin xyz=" 0 0 0 " rpy="0 0 0" />
<geometry>
<box size="0.01 0.04 0.04" />
</geometry>
<material name="Black"/>
</visual>
<collision>
<origin xyz="0.0 0.0 0.0" rpy="0 0 0" />
<geometry>
<box size="0.01 0.04 0.04" />
</geometry>
</collision>
</link>
<gazebo reference="usb_camera_link">
<material>Gazebo/Black</material>
</gazebo>
<gazebo reference="usb_camera_link">
<sensor type="camera" name="camera_node">
<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>
<mean>0.0</mean>
<stddev>0.007</stddev>
</noise>
</camera>
<plugin name="gazebo_camera" filename="libgazebo_ros_camera.so">
<alwaysOn>true</alwaysOn>
<updateRate>0.0</updateRate>
<cameraName>/camera</cameraName>
<imageTopicName>image_raw</imageTopicName>
<cameraInfoTopicName>camera_info</cameraInfoTopicName>
<frameName>usb_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>
</xacro:macro>
</robot>
运行display.launch文件加载robot.xacro
运行命令rostopic list，查看当前发布的话题，可以看到话题/camera/image_raw被发布
运行命令rqt_image_view订阅话题/camera/image_raw，可以看到摄像头拍摄的图像
由于暂时环境为空，所以显示灰色
后期可通过添加gazebo环境来体现摄像头的功能
原文地址：https://segmentfault.com/a/1190000022385115
