在rviz2中显示urdf模型

1.建立工作空间

cd /home/fishbot_ws/src
ros2 pkg create fishbot_description --build-type ament_python

2.创建并编写URDF文件

cd /home/fishbot_ws/src/fishbot_description
mkdir urdf
cd urdf
touch fishbot_base.urdf

完成后的src中的文件结构

├── fishbot_description
│   ├── __init__.py
├── package.xml
├── setup.cfg
├── setup.py
└── urdf
    └── fishbot_base.urdf

编辑fishbot_base.urdf

<?xml version="1.0"?>
<robot name="fishbot">
    
  <!-- base link -->
  <link name="base_link">
      <visual>
      <origin xyz="0 0 0.0" rpy="0 0 0"/>
      <geometry>
        <cylinder length="0.12" radius="0.10"/>
      </geometry>
    </visual>
  </link>
    
  <!-- laser link -->
  <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="black">
          <color rgba="0.0 0.0 0.0 0.8" /> 
      </material>
    </visual>
  </link>
    
  <!-- laser joint -->
    <joint name="laser_joint" type="fixed">
        <parent link="base_link" />
        <child link="laser_link" />
        <origin xyz="0 0 0.075" />
    </joint>

</robot>

3.创建并编写launch文件

cd /home/fishbot_ws/src/fishbot_description
mkdir launch
cd launch
touch display_rviz2.launch.py

完成后的目录结构

├── fishbot_description
│   ├── __init__.py
├── launch
│   └── display_rviz2.launch.py
├── package.xml
├── setup.cfg
├── setup.py
└── urdf
    └── fishbot_base.urdf

编辑launch文件

import os
from launch import LaunchDescription
from launch.substitutions import LaunchConfiguration
from launch_ros.actions import Node
from launch_ros.substitutions import FindPackageShare

def generate_launch_description():
    package_name = 'fishbot_description'
    urdf_name = "fishbot_base.urdf"

    ld = LaunchDescription()
    pkg_share = FindPackageShare(package=package_name).find(package_name) 
    urdf_model_path = os.path.join(pkg_share, f'urdf/{urdf_name}')

    robot_state_publisher_node = Node(
        package='robot_state_publisher',
        executable='robot_state_publisher',
        arguments=[urdf_model_path]
        )

    joint_state_publisher_node = Node(
        package='joint_state_publisher_gui',
        executable='joint_state_publisher_gui',
        name='joint_state_publisher_gui',
        arguments=[urdf_model_path]
        )

    rviz2_node = Node(
        package='rviz2',
        executable='rviz2',
        name='rviz2',
        output='screen',
        )

    ld.add_action(robot_state_publisher_node)
    ld.add_action(joint_state_publisher_node)
    ld.add_action(rviz2_node)

    return ld

• generate_launch_description() 函数是入口点，用于生成 LaunchDescription 对象，描述了启动的节点及其参数。
• FindPackageShare 类用于查找指定包的共享目录，以便获取该包中的资源文件。在这里，它用于获取机器人描述包（fishbot_description）的共享目录路径。
  - LaunchDescription 对象用于存储要启动的节点及其参数。

其中涉及三个节点:

• joint_state_publisher_gui 负责发布机器人关节数据信息，通过joint_states话题发布
• robot_state_publisher_node负责发布机器人模型信息robot_description，并将joint_states数据转换tf信息发布
• rviz2_node负责显示机器人的信息

最终，通过调用 ld.add_action() 将这些节点添加到 LaunchDescription 对象中，并将其返回，以便由 ROS 2 的启动系统加载并执行。

joint_state_publisher_gui，还有一个兄弟叫做joint_state_publisher
两者区别在于joint_state_publisher_gui运行起来会跳出一个界面，通过界面可以操作URDF中能动的关节

4.修改setup.py

from glob import glob
import os

完整setup.py

from setuptools import setup
from glob import glob
import os

package_name = 'fishbot_description'

setup(
    name=package_name,
    version='0.0.0',
    packages=[package_name],
    data_files=[
        ('share/ament_index/resource_index/packages',
            ['resource/' + package_name]),
        ('share/' + package_name, ['package.xml']),
        (os.path.join('share', package_name, 'launch'), glob('launch/*.launch.py')),
        (os.path.join('share', package_name, 'urdf'), glob('urdf/**')),
    ],
    install_requires=['setuptools'],
    zip_safe=True,
    maintainer='root',
    maintainer_email='root@todo.todo',
    description='TODO: Package description',
    license='TODO: License declaration',
    tests_require=['pytest'],
    entry_points={
        'console_scripts': [
        ],
    },
)

5.编译测试

回到工作空间(fishbot_ws)，编译

cd /home/fishbot_ws
colcon build

运行测试

source install/setup.bash
ros2 launch fishbot_description display_rviz2.launch.py