ROS2 launch时根据xacro生成urdf

ROS2 launch时根据xacro生成urdf

前言

本文简单记录如何在ros2 launch时生成urdf并保存到目标目录。

正文

from launch.substitutions import Command, FindExecutable, PathJoinSubstitution
from launch_ros.substitutions import FindPackageShare


def generate_launch_description():
    # 使用'xacro'生成urdf文件,并的保存至"r6bot.urdf"
    robot_description_content = Command(
        [
            PathJoinSubstitution([FindExecutable(name="xacro")]),
            " ",
            PathJoinSubstitution(
                [
                    FindPackageShare("ros2_control_demo_description"),
                    "r6bot",
                    "urdf",
                    "r6bot_description.urdf.xacro",
                ]
            ),
            " -o ",
            PathJoinSubstitution(
                [
                    FindPackageShare("ros2_control_demo_example_7"),
                    "urdf",
                    "r6bot.urdf",
                ]
            ),
        ]
    )
    robot_description = {"robot_description": robot_description_content}

解析：

Command()内部填写具体待执行程序；

PathJoinSubstitution([])拼接不同的路径到一起；

FindPackageShare("ros2_control_demo_description")寻找对应的ROS包的share路径（通常在CMakeLists.txt中定义install share）；

在之前的博文中《一文学会MoveIt Setup Assistant搭建moveit2机械臂模型-优快云博客》有写命令中-o参数的原因

对于xacro的使用说明可以参考官方文档《xacro — xacro 2.0.11 documentation (ros.org)》及《Using Xacro to clean up your code — ROS 2 Documentation: Humble documentation》