ROS2 第6章 使用URDF创建机器人
6.1 使用URDF创建机器人
在主目录下新建chapt6，在该目录下创建chapt6_ws，接着递归创建src目录，在src下创建fishbot_description。
ros2 pkg create fishbot_description --build-type ament_cmake --license Apache-2.0接着在fishbot_description下创建urdf目录，并在urdf目录下创建first_robot.urdf文件，代码如下
(可以先下载一个urdf扩展，帮助编写代码）
<?xml version="1.0"?> <!-- 机器人名称：first_robot --> <robot name="first_robot"> <!-- 1. 机器人身体部分（底座） --> <link name="base_link"> <!-- visual：描述部件的“外观”（形状、颜色，只影响显示，不影响物理） --> <visual> <!-- origin：部件自身的几何中心相对于“父关节”的偏移和旋转（这里是自身中心，所以全0） --> <origin xyz="0 0 0" rpy="0 0 0" /> <!-- geometry：部件的几何形状（这里是圆柱体） --> <geometry> <!-- cylinder：圆柱体，length=高度（0.12米），radius=半径（0.10米） --> <cylinder length="0.12" radius="0.10" /> </geometry> <!-- material：部件的材质（颜色） --> <material name="white"> <!-- color：颜色（rgba格式：红、绿、蓝、透明度，0-1之间） --> <color rgba="1.0 1.0 1.0 0.5" /> </material> </visual> </link> <!-- 2. 机器人IMU部件（惯性测量单元，用来测姿态） --> <link name="imu_link"> <visual> <origin xyz="0 0 0" rpy="0 0 0" /> <geometry> <!-- box：立方体，size=长×宽×高（0.02米×0.02米×0.02米，很小的方块） --> <box size="0.02 0.02 0.02" /> </geometry> <material name="black"> <color rgba="0 0 0 0.5" /> </material> </visual> </link> <!-- 3. 关节：连接base_link（底座）和imu_link（IMU） --> <joint name="imu_joint" type="fixed"> <parent link="base_link" /> <!-- 父部件：底座（IMU装在底座上） --> <child link="imu_link" /> <!-- origin：子部件（IMU）相对于父部件（底座）的位置和旋转 --> <!-- xyz="0 0 0.03"：IMU在底座的正上方0.03米处（z轴向上），x/y方向对齐（0,0） --> <origin xyz="0 0 0.03" rpy="0 0 0" /> </joint> </robot>编写完成后，在终端中进入urdf目录下，输入以下代码将URDF结构可视化，结果如下
~/chapt6/chapt6_ws/src/fishbot_description/urdf$ urdf_to_graphviz first_robot.urdf first_robot Created file first_robot.gv Created file first_robot.pdf打开生成的first_robot.pdf内容如下：
6.2 在Rviz中显示机器人
安装依赖
sudo apt install ros-$ROS_DISTRO-robot-state-publisher sudo apt install ros-$ROS_DISTRO-joint-state-publisher为了方便运行，使用launch文件组织节点，在fishbot_description目录下新建launch目录，接着创建display_robot.launch.py，写入以下代码
import launch import launch_ros from ament_index_python.packages import get_package_share_directory def generate_launch_description(): urdf_turtorial_path = get_package_share_directory('fishbot_description') default_model_path = urdf_turtorial_path + '/urdf/first_robot.urdf' action_delcare_arg_mode_path = launch.actions.DeclareLaunchArgument( name='model', default_value=str(default_model_path), description='URDF 的绝对路径') robot_description = launch_ros.parameter_descriptions.ParameterValue( launch.substitutions.Command( ['cat ', launch.substitutions.LaunchConfiguration('model')]), value_type=str) robot_state_publisher_node = launch_ros.actions.Node( package='robot_state_publisher', executable='robot_state_publisher', parameters=[{'robot_description':robot_description}] ) joint_state_publisher_node = launch_ros.actions.Node( package='joint_state_publisher', executable='joint_state_publisher', ) rviz_node = launch_ros.actions.Node( package='rviz2', executable='rviz2', ) return launch.LaunchDescription([ action_delcare_arg_mode_path, joint_state_publisher_node, robot_state_publisher_node, rviz_node ])代码完成后，在CMakeLists.txt中将urdf和launch文件复制到install目录下，代码如下
install(DIRECTORY launch urdf DESTINATION share/${PROJECT_NAME}) 随后在工作空间下构建功能包，source 并启动launch文件，启动命令与结果如下
~/chapt6/chapt6_ws$ ros2 launch fishbot_description display_robot.launch.py [INFO] [launch]: All log files can be found below /home/cwq/.ros/log/2025-11-06-20-50-29-922420-cwq-virtual-machine-12869 [INFO] [launch]: Default logging verbosity is set to INFO [INFO] [joint_state_publisher-1]: process started with pid [12871] [INFO] [robot_state_publisher-2]: process started with pid [12873] [INFO] [rviz2-3]: process started with pid [12875] [rviz2-3] qt.qpa.plugin: Could not find the Qt platform plugin "wayland" in "" [robot_state_publisher-2] [INFO] [1762433430.026086874] [robot_state_publisher]: got segment base_link [robot_state_publisher-2] [INFO] [1762433430.026263877] [robot_state_publisher]: got segment imu_link [joint_state_publisher-1] [INFO] [1762433430.485811579] [joint_state_publisher]: Waiting for robot_description to be published on the robot_description topic... [rviz2-3] [INFO] [1762433430.610920615] [rviz2]: Stereo is NOT SUPPORTED [rviz2-3] [INFO] [1762433430.611039547] [rviz2]: OpenGl version: 4.3 (GLSL 4.3) [rviz2-3] [INFO] [1762433430.643061933] [rviz2]: Stereo is NOT SUPPORTED需要将Rviz的Display模块中的Fixed Frame修改为base_link,添加RobotModel并修改Description Source为Topic，在Description Topic处选择/robot_description。
在launch中添加启动rviz2命令
def generate_launch_description(): urdf_turtorial_path = get_package_share_directory('fishbot_description') default_model_path = urdf_turtorial_path + '/urdf/first_robot.urdf' default_rviz_config_path = urdf_turtorial_path + '/config/display_model.rviz' arguments=['-d', default_rviz_config_path]修改完后，修改CMakeLIsts.txt，将config目录复制到install对应目录下，重新构建功能包并运行launch文件，即可显示机器人模型
6.3 使用Xacro简化URDF
在urdf目录下创建first_robot.urdf.xacro，编写以下代码
<?xml version="1.0"?> <!-- 机器人名称：first_robot --> <robot xmlns:xacro="http://www.ros.org/wiki/xacro" name="first_robot"> <xacro:macro name="base_link" params="length radius"> <!-- 1. 机器人身体部分（底座） --> <link name="base_link"> <!-- visual：描述部件的“外观”（形状、颜色，只影响显示，不影响物理） --> <visual> <!-- origin：部件自身的几何中心相对于“父关节”的偏移和旋转（这里是自身中心，所以全0） --> <origin xyz="0 0 0" rpy="0 0 0" /> <!-- geometry：部件的几何形状（这里是圆柱体） --> <geometry> <cylinder length="${length}" radius="${radius}" /> </geometry> <!-- material：部件的材质（颜色） --> <material name="white"> <!-- color：颜色（rgba格式：红、绿、蓝、透明度，0-1之间） --> <color rgba="1.0 1.0 1.0 0.5" /> </material> </visual> </link> </xacro:macro> <xacro:macro name="imu_link" params="imu_name xyz"> <!-- 2. 机器人IMU部件（惯性测量单元，用来测姿态） --> <link name="${imu_name}_link"> <visual> <origin xyz="0 0 0" rpy="0 0 0" /> <geometry> <!-- box：立方体，size=长×宽×高（0.02米×0.02米×0.02米，很小的方块） --> <box size="0.02 0.02 0.02" /> </geometry> <material name="black"> <color rgba="0 0 0 0.5" /> </material> </visual> </link> <!-- 3. 关节：连接base_link（底座）和imu_link（IMU） --> <joint name="${imu_name}_joint" type="fixed"> <parent link="base_link" /> <!-- 父部件：底座（IMU装在底座上） --> <child link="${imu_name}_link" /> <!-- origin：子部件（IMU）相对于父部件（底座）的位置和旋转 --> <!-- xyz="0 0 0.03"：IMU在底座的正上方0.03米处（z轴向上），x/y方向对齐（0,0） --> <origin xyz="${xyz}" /> </joint> </xacro:macro> <xacro:base_link length="0.12" radius="0.1" /> <xacro:imu_link imu_name="imu_up" xyz="0 0 0.02" /> <xacro:imu_link imu_name="imu_down" xyz="0 0 -0.02" /> </robot>在终端中安装xacro工具，将xacro解析成URDF格式
sudo apt install ros-$ROS_DISTRO-xacro在终端进入fishbot_description/urdf目录，使用以下代码将Xacro解析为URDF
~/chapt6/chapt6_ws/src/fishbot_description/urdf$ xacro first_robot.urdf.xacro <?xml version="1.0" ?> <!-- =================================================================================== --> <!-- | This document was autogenerated by xacro from first_robot.urdf.xacro | --> <!-- | EDITING THIS FILE BY HAND IS NOT RECOMMENDED | --> <!-- =================================================================================== --> <!-- 机器人名称：first_robot --> <robot name="first_robot"> <!-- 1. 机器人身体部分（底座） --> <link name="base_link"> <!-- visual：描述部件的“外观”（形状、颜色，只影响显示，不影响物理） --> <visual> <!-- origin：部件自身的几何中心相对于“父关节”的偏移和旋转（这里是自身中心，所以全0） --> <origin rpy="0 0 0" xyz="0 0 0"/> <!-- geometry：部件的几何形状（这里是圆柱体） --> <geometry> <cylinder length="0.12" radius="0.1"/> </geometry> <!-- material：部件的材质（颜色） --> <material name="white"> <!-- color：颜色（rgba格式：红、绿、蓝、透明度，0-1之间） --> <color rgba="1.0 1.0 1.0 0.5"/> </material> </visual> </link> <!-- 2. 机器人IMU部件（惯性测量单元，用来测姿态） --> <link name="imu_up_link"> <visual> <origin rpy="0 0 0" xyz="0 0 0"/> <geometry> <!-- box：立方体，size=长×宽×高（0.02米×0.02米×0.02米，很小的方块） --> <box size="0.02 0.02 0.02"/> </geometry> <material name="black"> <color rgba="0 0 0 0.5"/> </material> </visual> </link> <!-- 3. 关节：连接base_link（底座）和imu_link（IMU） --> <joint name="imu_up_joint" type="fixed"> <parent link="base_link"/> <!-- 父部件：底座（IMU装在底座上） --> <child link="imu_up_link"/> <!-- origin：子部件（IMU）相对于父部件（底座）的位置和旋转 --> <!-- xyz="0 0 0.03"：IMU在底座的正上方0.03米处（z轴向上），x/y方向对齐（0,0） --> <origin xyz="0 0 0.02"/> </joint> <!-- 2. 机器人IMU部件（惯性测量单元，用来测姿态） --> <link name="imu_down_link"> <visual> <origin rpy="0 0 0" xyz="0 0 0"/> <geometry> <!-- box：立方体，size=长×宽×高（0.02米×0.02米×0.02米，很小的方块） --> <box size="0.02 0.02 0.02"/> </geometry> <material name="black"> <color rgba="0 0 0 0.5"/> </material> </visual> </link> <!-- 3. 关节：连接base_link（底座）和imu_link（IMU） --> <joint name="imu_down_joint" type="fixed"> <parent link="base_link"/> <!-- 父部件：底座（IMU装在底座上） --> <child link="imu_down_link"/> <!-- origin：子部件（IMU）相对于父部件（底座）的位置和旋转 --> <!-- xyz="0 0 0.03"：IMU在底座的正上方0.03米处（z轴向上），x/y方向对齐（0,0） --> <origin xyz="0 0 -0.02"/> </joint> </robot>将display_robot.launch.py中的'cat'命令替换为'xacro'。
在工作空间下重新构建和启动launch文件，并修改model参数为对应的文件地址，即可更新生成机器人模型。
~/chapt6/chapt6_ws$ ros2 launch fishbot_description display_robot.launch.py model:=/home/cwq/chapt6/chapt6_ws/src/fishbot_description/urdf/first_robot.urdf.xacro [INFO] [launch]: All log files can be found below /home/cwq/.ros/log/2025-11-07-17-31-27-774942-cwq-virtual-machine-21242 [INFO] [launch]: Default logging verbosity is set to INFO [INFO] [joint_state_publisher-1]: process started with pid [21244] [INFO] [robot_state_publisher-2]: process started with pid [21246] [INFO] [rviz2-3]: process started with pid [21248] [rviz2-3] qt.qpa.plugin: Could not find the Qt platform plugin "wayland" in "" [robot_state_publisher-2] [INFO] [1762507887.971557955] [robot_state_publisher]: got segment base_link [robot_state_publisher-2] [INFO] [1762507887.971697529] [robot_state_publisher]: got segment imu_down_link [robot_state_publisher-2] [INFO] [1762507887.971708736] [robot_state_publisher]: got segment imu_up_link [rviz2-3] [INFO] [1762507888.289264420] [rviz2]: Stereo is NOT SUPPORTED [rviz2-3] [INFO] [1762507888.289391344] [rviz2]: OpenGl version: 4.3 (GLSL 4.3) [rviz2-3] [INFO] [1762507888.321751638] [rviz2]: Stereo is NOT SUPPORTED [joint_state_publisher-1] [INFO] [1762507888.333985018] [joint_state_publisher]: Waiting for robot_description to be published on the robot_description topic...6.4 创建机器人及传感器部件
在fishbot_description/urdf/目录下新建fisbot目录，在该目录下新建base.urdf.xacro，写入以下代码
<?xml version="1.0"?> <robot xmlns:xacro="http://www.ros.org/wiki/xacro"> <xacro:macro name="base_xacro" params="length radius"> <link name="base_link"> <visual> <origin xyz="0 0 0" rpy="0 0 0" /> <geometry> <cylinder length="${length}" radius="${radius}" /> </geometry> <material name="white"> <color rgba="1.0 1.0 1.0 0.5" /> </material> </visual> </link> </xacro:macro> </robot>在fishbot目录下新建sensor子目录，在sensor下新建imu.urdf.xacro，写入以下代码
<?xml version="1.0"?> <robot xmlns:xacro="http://www.ros.org/wiki/xacro"> <xacro:macro name="imu_xacro" params="xyz"> <link name="imu_link"> <visual> <origin xyz="0 0 0" rpy="0 0 0" /> <geometry> <box size="0.02 0.02 0.02" /> </geometry> <material name="black"> <color rgba="0 0 0 0.8" /> </material> </visual> </link> <joint name="imu_joint" type="fixed"> <parent link="base_link" /> <child link="imu_link" /> <origin xyz="${xyz}" /> </joint> </xacro:macro> </robot>在sensor下新建camera.urdf.xacro，写入以下代码
<?xml version="1.0"?> <robot xmlns:xacro="http://www.ros.org/wiki/xacro"> <xacro:macro name="camera_xacro" params="xyz"> <link name="camera_link"> <visual> <origin xyz="0 0 0.0" rpy="0 0 0" /> <geometry> <box size="0.02 0.10 0.02" /> </geometry> <material name="green"> <color rgba="0.0 1.0 0.0 0.8" /> </material> </visual> </link> <joint name="camera_joint" type="fixed"> <parent link="base_link" /> <child link="camera_link" /> <origin xyz="${xyz}" /> </joint> </xacro:macro> </robot>在sensor下新建laser.urdf.xacro，写入以下代码
<?xml version="1.0"?> <robot xmlns:xacro="http://www.ros.org/wiki/xacro"> <xacro:macro name="laser_xacro" params="xyz"> <link name="laser_cylinder_link"> <visual> <origin xyz="0 0 0" rpy="0 0 0" /> <geometry> <cylinder length="0.10" radius="0.01" /> </geometry> <material name="green"> <color rgba="0.0 1.0 0.0 0.8" /> </material> </visual> </link> <joint name="laser_cylinder_joint" type="fixed"> <parent link="base_link" /> <child link="laser_cylinder_link" /> <origin xyz="${xyz}" /> </joint> <link name="laser_link"> <visual> <origin xyz="0 0 0" rpy="0 0 0" /> <geometry> <cylinder length="0.02" radius="0.02" /> </geometry> <material name="green"> <color rgba="0.0 1.0 0.0 0.8" /> </material> </visual> </link> <joint name="laser_joint" type="fixed"> <parent link="laser_cylinder_link" /> <child link="laser_link" /> <origin xyz="0 0 0.05" /> </joint> </xacro:macro> </robot>传感器代码完成，现在需要将传感器组装起来，在urdf/fishbot/下新建fishbot.urdf.xacro，写入以下代码
<?xml version="1.0"?> <robot xmlns:xacro="http://www.ros.org/wiki/xacro" name="first_robot"> <xacro:include filename="$(find fishbot_description)/urdf/fishbot/base.urdf.xacro" /> <xacro:include filename="$(find fishbot_description)/urdf/fishbot/sensor/imu.urdf.xacro" /> <xacro:include filename="$(find fishbot_description)/urdf/fishbot/sensor/laser.urdf.xacro" /> <xacro:include filename="$(find fishbot_description)/urdf/fishbot/sensor/camera.urdf.xacro" /> <xacro:base_xacro length="0.12" radius="0.1" /> <xacro:imu_xacro xyz="0 0 0.02" /> <xacro:laser_xacro xyz="0 0 0.10" /> <xacro:camera_xacro xyz="0.10 0 0.075" /> </robot>重新编译并运行display_robot.launch.py(需将路径改为fishbot.urdf.xacro，代码及显示结果如下
ros2 launch fishbot_description display_robot.launch.py model:=/home/cwq/chapt6/chapt6_ws/src/fishbot_description/urdf/fishbot/fishbot.urdf.xacro [INFO] [launch]: All log files can be found below /home/cwq/.ros/log/2025-11-07-18-08-07-719699-cwq-virtual-machine-21855 [INFO] [launch]: Default logging verbosity is set to INFO [INFO] [joint_state_publisher-1]: process started with pid [21857] [INFO] [robot_state_publisher-2]: process started with pid [21859] [INFO] [rviz2-3]: process started with pid [21861] [rviz2-3] qt.qpa.plugin: Could not find the Qt platform plugin "wayland" in "" [robot_state_publisher-2] [INFO] [1762510087.926664599] [robot_state_publisher]: got segment base_link [robot_state_publisher-2] [INFO] [1762510087.926850670] [robot_state_publisher]: got segment camera_link [robot_state_publisher-2] [INFO] [1762510087.926862145] [robot_state_publisher]: got segment imu_link [robot_state_publisher-2] [INFO] [1762510087.926868633] [robot_state_publisher]: got segment laser_cylinder_link [robot_state_publisher-2] [INFO] [1762510087.926874791] [robot_state_publisher]: got segment laser_link [joint_state_publisher-1] [INFO] [1762510088.451227984] [joint_state_publisher]: Waiting for robot_description to be published on the robot_description topic... [rviz2-3] [INFO] [1762510088.605421457] [rviz2]: Stereo is NOT SUPPORTED [rviz2-3] [INFO] [1762510088.605605758] [rviz2]: OpenGl version: 4.3 (GLSL 4.3) [rviz2-3] [INFO] [1762510088.638243716] [rviz2]: Stereo is NOT SUPPORTED
6.5 完善机器人执行器部件
在fishbot目录下新建actuator子目录，然后在actuator下新建wheel.urdf.wacro，编写以下代码
<?xml version="1.0"?> <robot xmlns:xacro="http://www.ros.org/wiki/xacro"> <xacro:macro name="wheel_xacro" params="wheel_name xyz"> <link name="${wheel_name}_wheel_link"> <visual> <origin xyz="0 0 0" rpy="1.57079 0 0" /> <geometry> <cylinder length="0.04" radius="0.032" /> </geometry> <material name="yellow"> <color rgba="1.0 1.0 0.0 0.8" /> </material> </visual> </link> <joint name="${wheel_name}_wheel_joint" type="continuous"> <parent link="base_link" /> <child link="${wheel_name}_wheel_link" /> <origin xyz="${xyz}" /> <axis xyz="0.0 1.0 0.0"/> </joint> </xacro:macro> </robot>完成驱动轮的定义，接着定义万向轮部分，在actuator中新建caster.urdf.xacro文件，代码如下
<?xml version="1.0"?> <robot xmlns:xacro="http://www.ros.org/wiki/xacro"> <xacro:macro name="caster_xacro" params="caster_name xyz"> <link name="${caster_name}_caster_link"> <visual> <origin xyz="0 0 0" rpy="0 0 0" /> <geometry> <sphere radius="0.016" /> </geometry> <material name="yellow"> <color rgba="1.0 1.0 0.0 0.8" /> </material> </visual> </link> <joint name="${caster_name}_caster_joint" type="fixed"> <parent link="base_link" /> <child link="${caster_name}_caster_link" /> <origin xyz="${xyz}" /> <axis xyz="0 0 0"/> </joint> </xacro:macro> </robot>完成后再次修改fishbot.urdf.xacro，添加代码如下，
<xacro:include filename="$(find fishbot_description)/urdf/fishbot/actuator/caster.urdf.xacro" /> <xacro:include filename="$(find fishbot_description)/urdf/fishbot/actuator/wheel.urdf.xacro" /> <xacro:wheel_xacro wheel_name="left" xyz="0 0.10 -0.06" /> <xacro:wheel_xacro wheel_name="right" xyz="0 -0.10 -0.06" /> <xacro:caster_xacro caster_name="front" xyz="0.08 0.0 -0.076" /> <xacro:caster_xacro caster_name="back" xyz="-0.08 0.0 -0.076" />在rviz中观察机器人，发现机器人轮子在地面以下，通过添加虚拟关节来解决这一问题，在src/fishbot_description/urdf/fishbot/base.urdf.xacro中添加以下代码，
<link name="base_footprint" /> <joint name="base_joint" type="fixed"> <parent link="base_footprint" /> <child link="base_link" /> <origin xyz="0.0 0.0 ${length/2.0+0.032-0.001}" rpy="0 0 0" /> </joint> 保存好后构建运行，修改fixed frame 为base_footprint，代码及结果展示如下：
ros2 launch fishbot_description display_robot.launch.py model:=/home/cwq/chapt6/chapt6_ws/src/fishbot_description/urdf/fishbot/fishbot.urdf.xacro [INFO] [launch]: All log files can be found below /home/cwq/.ros/log/2025-11-07-20-22-50-038490-cwq-virtual-machine-22899 [INFO] [launch]: Default logging verbosity is set to INFO [INFO] [joint_state_publisher-1]: process started with pid [22901] [INFO] [robot_state_publisher-2]: process started with pid [22903] [INFO] [rviz2-3]: process started with pid [22905] [rviz2-3] qt.qpa.plugin: Could not find the Qt platform plugin "wayland" in "" [robot_state_publisher-2] [INFO] [1762518170.255450518] [robot_state_publisher]: got segment back_caster_link [robot_state_publisher-2] [INFO] [1762518170.255583911] [robot_state_publisher]: got segment base_footprint [robot_state_publisher-2] [INFO] [1762518170.255595068] [robot_state_publisher]: got segment base_link [robot_state_publisher-2] [INFO] [1762518170.255601575] [robot_state_publisher]: got segment camera_link [robot_state_publisher-2] [INFO] [1762518170.255607770] [robot_state_publisher]: got segment front_caster_link [robot_state_publisher-2] [INFO] [1762518170.255613439] [robot_state_publisher]: got segment imu_link [robot_state_publisher-2] [INFO] [1762518170.255619158] [robot_state_publisher]: got segment laser_cylinder_link [robot_state_publisher-2] [INFO] [1762518170.255624824] [robot_state_publisher]: got segment laser_link [robot_state_publisher-2] [INFO] [1762518170.255630704] [robot_state_publisher]: got segment left_wheel_link [robot_state_publisher-2] [INFO] [1762518170.255636445] [robot_state_publisher]: got segment right_wheel_link [joint_state_publisher-1] [INFO] [1762518170.778521917] [joint_state_publisher]: Waiting for robot_description to be published on the robot_description topic...
6.6 添加物理属性让机器人更真实
6.6.1 为机器人添加碰撞属性
为每个部件都添加一份碰撞属性，与visual同级，添加<collision>，将visual的内容直接复制粘贴即可，base , laser , wheel , caster 都添加一次。
</visual> <collision> <origin xyz="0 0 0" rpy="0 0 0" /> <geometry> <sphere radius="0.016" /> </geometry> <material name="yellow"> <color rgba="1.0 1.0 0.0 0.8" /> </material> </collision> </link>在终端运行，打开rviz后，修改RobotModel配置，去掉VIsual Enabled的勾选，再勾选上Collsion Enabled即可显示出碰撞模型。.
6.6.2 为机器人部件添加质量与惯性
使用xacro结合惯性公式，编写一个惯性和质量专用的宏定义，在urdf/fishbot目录下新建common_inertia.xacro文件，编写以下代码
<?xml version="1.0"?> <robot xmlns:xacro="http://ros.org/wiki/xacro"> <xacro:macro name="box_inertia" params="m w h d"> <inertial> <mass value="${m}" /> <inertia ixx="${(m/12) * (h*h + d*d)}" ixy="0.0" ixz="0.0" iyy="${(m/12) * (w*w + d*d)}" iyz="0.0" izz="${(m/12) * (w*w + h*h)}" /> </inertial> </xacro:macro> <xacro:macro name="cylinder_inertia" params="m r h"> <inertial> <mass value="${m}" /> <inertia ixx="${(m/12) * (3*r*r + h*h)}" ixy="0" ixz="0" iyy="${(m/12) * (3*r*r + h*h)}" iyz="0" izz="${(m/2) * (r*r)}" /> </inertial> </xacro:macro> <xacro:macro name="sphere_inertia" params="m r"> <inertial> <mass value="${m}" /> <inertia ixx="${(2/5) * m * (r*r)}" ixy="0.0" ixz="0.0" iyy="${(2/5) * m * (r*r)}" iyz="0.0" izz="${(2/5) * m * (r*r)}" /> </inertial> </xacro:macro> </robot> 编写完成后，就可以在其它xacro文件导入并使用该宏，修改base.urdf.xacro，添加导入对该宏的调用，
<?xml version="1.0"?> <robot xmlns:xacro="http://www.ros.org/wiki/xacro"> <xacro:include filename="$(find fishbot_description)/urdf/fishbot/common_inertia.xacro" /> <xacro:macro name="base_xacro" params="length radius"> <link name="base_footprint" /> <joint name="base_joint" type="fixed"> <parent link="base_footprint" /> <child link="base_link" /> <origin xyz="0.0 0.0 ${length/2.0+0.032-0.001}" rpy="0 0 0" /> </joint> <link name="base_link"> <visual> <origin xyz="0 0 0.0" rpy="0 0 0" /> <geometry> <cylinder length="${length}" radius="${length}" /> </geometry> <material name="blue"> <color rgba="0.1 0.1 1.0 0.5"/> </material> </visual> <collision> <origin xyz="0 0 0.0" rpy="0 0 0" /> <geometry> <cylinder length="${length}" radius="${length}" /> </geometry> <material name="blue"> <color rgba="0.1 0.1 1.0 0.5"/> </material> </collision> <xacro:cylinder_inertia m="1.0" r="${radius}" h="${length}"/> </link> </xacro:macro> </robot> 这里给出的完整代码，读者可对照修改。再次构建并运行launch，在rviz中显示机器人模型。
接着修改robotmodel配置，取消visual enabled的勾选，然后勾选mass properties选项中的mass，即可看到质量配置视图，取消mass勾选，勾选inertia视图，即可看到惯性视图。
下一章写如何在gazebo中仿真
