一、安装Rviz，用它显示电脑摄像头的视频
*准备工作*
安装好ubuntu18.04、ROSmelodic版本
*步骤*
*1）更改虚拟机USB设置为3.0，并连接摄像头（查看摄像头可用命令cheese）*
2）**安装相关功能包**
安装uvc camera功能包：sudo apt-get install ros-melodic-uvc-camera
安装image相关功能包：sudo apt-get install ros-melodic-image-*
sudo apt-get install ros-melodic-rqt-image-view
3）**启动**
1. *启动ROS的核心程序*
roscore
2. *在另一个终端运行uvc_camera节点*
rosrun uvc_camera uvc_camera_node
3. 另外开一个终端查看话题信息和打印相机信息
rostopic list
rostopic echo /camera_info
4. *打开rivz*
rivz
5. *配置rivz*
4）**结果展示**
二、gazebo仿真
配置机器人模型
创建仿真环境
开始仿真
cd ~/catkin_ws/src/mbot_description/urdf/xacro
mkdir gazebo
cd gazebo
sudo gedit mbot_base_gazebo.xacro
声明xml文件
各link的质量（mass）属性声明及其他常量声明
<!-- PROPERTY LIST -->
<xacro:property name="M_PI" value="3.1415926"/>
<xacro:property name="base_mass" value="20" />
<xacro:property name="base_radius" value="0.20"/>
<xacro:property name="base_length" value="0.16"/>
<xacro:property name="wheel_mass" value="2" />
<xacro:property name="wheel_radius" value="0.06"/>
<xacro:property name="wheel_length" value="0.025"/>
<xacro:property name="wheel_joint_y" value="0.19"/>
<xacro:property name="wheel_joint_z" value="0.05"/>
<xacro:property name="caster_mass" value="0.5" />
<xacro:property name="caster_radius" value="0.015"/> <!-- wheel_radius - ( base_length/2 - wheel_joint_z) -->
<xacro:property name="caster_joint_x" value="0.18"/>
颜色属性说明
<!-- Defining the colors used in this robot -->
<material name="yellow">
<color rgba="1 0.4 0 1"/>
</material>
<material name="black">
<color rgba="0 0 0 0.95"/>
</material>
<material name="gray">
<color rgba="0.75 0.75 0.75 1"/>
</material>
宏定义 球体惯性矩阵计算
<!-- Macro for inertia matrix -->
<xacro:macro name="sphere_inertial_matrix" params="m r">
<inertial>
<mass value="${m}" />
<inertia ixx="${2*m*r*r/5}" ixy="0" ixz="0"
iyy="${2*m*r*r/5}" iyz="0"
izz="${2*m*r*r/5}" />
</inertial>
</xacro:macro>
宏定义 圆柱体惯性矩阵计算
<xacro:macro name="cylinder_inertial_matrix" params="m r h">
<inertial>
<mass value="${m}" />
<inertia ixx="${m*(3*r*r+h*h)/12}" ixy = "0" ixz = "0"
iyy="${m*(3*r*r+h*h)/12}" iyz = "0"
izz="${m*r*r/2}" />
</inertial>
</xacro:macro>
宏定义 驱动轮
<!-- Macro for robot wheel -->
<xacro:macro name="wheel" params="prefix reflect">
<joint name="${prefix}_wheel_joint" type="continuous">
<origin xyz="0 ${reflect*wheel_joint_y} ${-wheel_joint_z}" rpy="0 0 0"/>
<parent link="base_link"/>
<child link="${prefix}_wheel_link"/>
<axis xyz="0 1 0"/>
</joint>
<link name="${prefix}_wheel_link">
<visual>
<origin xyz="0 0 0" rpy="${M_PI/2} 0 0" />
<geometry>
<cylinder radius="${wheel_radius}" length = "${wheel_length}"/>
</geometry>
<material name="gray" />
</visual>
<!-- collision -->
<!-- the same with visual -->
<!--增加惯性属性和碰撞属性-->
<collision>
<origin xyz="0 0 0" rpy="${M_PI/2} 0 0" />
<geometry>
<cylinder radius="${wheel_radius}" length = "${wheel_length}"/>
</geometry>
</collision>
<!-- inertial -->
<cylinder_inertial_matrix m="${wheel_mass}" r="${wheel_radius}" h="${wheel_length}" />
</link>
<!--添加gazebo标签为各link配颜色 ，gazebo与rivz颜色设置不兼容-->
<!-- Add gazebo tag to link -->
<gazebo reference="${prefix}_wheel_link">
<material>Gazebo/Gray</material>
</gazebo>
<!--joint添加传动装置,用得 transmission 标签,小车轮子用速度控制接口-->
<!-- Transmission is important to link the joints and the controller -->
<transmission name="${prefix}_wheel_joint_trans">
<type>transmission_interface/SimpleTransmission</type>
<joint name="${prefix}_wheel_joint" >
<hardwareInterface>hardware_interface/VelocityJointInterface</hardwareInterface>
</joint>
<actuator name="${prefix}_wheel_joint_motor">
<hardwareInterface>hardware_interface/VelocityJointInterface</hardwareInterface>
<mechanicalReduction>1</mechanicalReduction>
</actuator>
</transmission>
</xacro:macro>
宏定义 前后轮
<!-- Macro for robot caster -->
<xacro:macro name="caster" params="prefix reflect">
<joint name="${prefix}_caster_joint" type="continuous">
<origin xyz="${reflect*caster_joint_x} 0 ${-(base_length/2 + caster_radius)}" rpy="0 0 0"/>
<parent link="base_link"/>
<child link="${prefix}_caster_link"/>
<axis xyz="0 1 0"/>
</joint>
<link name="${prefix}_caster_link">
<visual>
<origin xyz="0 0 0" rpy="0 0 0"/>
<geometry>
<sphere radius="${caster_radius}" />
</geometry>
<material name="black" />
</visual>
<!-- 碰撞属性 -->
<collision>
<origin xyz="0 0 0" rpy="0 0 0"/>
<geometry>
<sphere radius="${caster_radius}" />
</geometry>
</collision>
<!-- 惯性属性 -->
<sphere_inertial_matrix m="${caster_mass}" r="${caster_radius}" />
</link>
<!--添加gazebo标签,为各link配颜色-->
<gazebo reference="${prefix}_caster_link">
<material>Gazebo/Black</material>
</gazebo>
</xacro:macro>
定义主体base并添加内容
<xacro:macro name="mbot_base_gazebo">
<link name="base_footprint">
<visual>
<origin xyz="0 0 0" rpy="0 0 0" />
<geometry>
<box size="0.001 0.001 0.001" />
</geometry>
</visual>
</link>
<!-- 给 base_footprint 添加标签 -->
<gazebo reference="base_footprint">
<turnGravityOff>false</turnGravityOff>
</gazebo>
<joint name="base_footprint_joint" type="fixed">
<origin xyz="0 0 ${base_length/2 + caster_radius*2}" rpy="0 0 0" />
<parent link="base_footprint"/>
<child link="base_link" />
</joint>
<!--base_link添加碰撞属性和惯性属性-->
<link name="base_link">
<visual>
<origin xyz=" 0 0 0" rpy="0 0 0" />
<geometry>
<cylinder length="${base_length}" radius="${base_radius}"/>
</geometry>
<material name="yellow" />
</visual>
<collision>
<origin xyz=" 0 0 0" rpy="0 0 0" />
<geometry>
<cylinder length="${base_length}" radius="${base_radius}"/>
</geometry>
</collision>
<cylinder_inertial_matrix m="${base_mass}" r="${base_radius}" h="${base_length}" />
</link>
<!--base_link添加gazebo标签-->
<gazebo reference="base_link">
<material>Gazebo/Blue</material>
</gazebo>
<wheel prefix="left" reflect="-1"/> <!-- 调用驱动轮子宏定义 -->
<wheel prefix="right" reflect="1"/> <!-- 调用驱动轮子宏定义 -->
<caster prefix="front" reflect="-1"/> <!--调用支撑轮子宏定义-->
<caster prefix="back" reflect="1"/>