RVIZ2可视化移动机器人模型
上一节讲完joint和link，我们来把我们上面定义的简单的URDF(包含身体和雷达)用RVIZ2显示出来，直观的感受下，我们的机器人模型。
URDF可视化的步骤如下：
1建立机器人描述功能包
2建立urdf文件夹编写urdf文件
3建立launch文件夹，编写launch文件
4修改setup.py配置，编译测试
1.建立功能包
轻车熟路，先创建一个fishbot_ws工作空间，然后建立功能包，包的类型选ament_python
ros2 pkg create fishbot_description --build-type ament_python
2.建立URDF文件
建立URDF文件夹，创建urdf文件
cd fishbot_description && mkdir urdf
touch fishbot_base.urdf
完成后的目录结构：
├── 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.建立launch文件
在目录src/fishbot_description下创建launch文件夹下并新建display_rviz2.launch.py文件。
mkdir 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
import os
from launch import LaunchDescription
from launch.substitutions import LaunchConfiguration
from launch_ros.actions import Node
from launch_ros.substitutions import FindPackageSharedef 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
想要可视化模型需要三个节点参与
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
这里我们用到了joint_state_publisher_gui和robot_state_publisher两个包,如果你的系统没有安装这两个包,可以手动安装:
sudo apt install ros-$ROS_DISTRO-joint-state-publisher-gui ros-$ROS_DISTRO-robot-state-publisher
joint_state_publisher_gui，还有一个兄弟叫做joint_state_publisher两者区别在与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
导入头
from glob import glob
import os
加入目录安装
('share/ament_index/resource_index/packages',
['resource/' + package_name]),
('share/' + package_name, ['package.xml']),完整
from setuptools import setup
from glob import glob
import ospackage_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
编译
colcon build
运行测试
source install/setup.bash
ros2 launch fishbot_description display_rviz2.launch.py
添加robotmodel模块，分别选择link名称如下，即可看到机器人的模型显示
这里大家可以参考图理一理launch文件中启动的三个节点的关系。
然后打开TF模块，看一下机器人的坐标系关系
6.本节练习
练习1：尝试将修改机器人身体颜色为蓝色，透明度为50%(0.1 0.1 1.0 0.5)
练习2：尝试在URDF中添加imu_link并使用imu_joint将其固定在车体的中心上方2cm，imu采用的几何形状为box。长宽高各是2cm
结果展示：
)
