Gazebo 使用方式与典型场景

四、使用方式与典型场景

示例一：差速小车模型的关键片段

下面是一个 SDF 模型里「差速驱动插件」的配置片段，把轮子与控制器连起来：

<plugin filename="gz-sim-diff-drive-system"
        name="gz::sim::systems::DiffDrive">
  <left_joint>left_wheel_joint</left_joint>
  <right_joint>right_wheel_joint</right_joint>
  <wheel_separation>0.34</wheel_separation>
  <wheel_radius>0.06</wheel_radius>
  <max_linear_acceleration>1.0</max_linear_acceleration>
  <max_angular_acceleration>2.0</max_angular_acceleration>
  <odom_publish_frequency>50</odom_publish_frequency>
  <topic>cmd_vel</topic>
  <odom_topic>odom</odom_topic>
</plugin>

轮距和轮半径必须与几何模型完全一致，写错了最直接的表现就是「走直线跑偏、转 90 度转成 80 度」。

示例二：启动世界、生成机器人并桥接话题

from launch import LaunchDescription
from launch.actions import ExecuteProcess, IncludeLaunchDescription
from launch.launch_description_sources import PythonLaunchDescriptionSource
from launch_ros.actions import Node
from ament_index_python.packages import get_package_share_directory
import os


def generate_launch_description():
    pkg = get_package_share_directory("my_robot")
    world = os.path.join(pkg, "worlds", "warehouse.sdf")
    bridge_cfg = os.path.join(pkg, "config", "bridge.yaml")

    gz_sim = ExecuteProcess(
        cmd=["gz", "sim", "-r", world],
        output="screen",
    )

    spawn = Node(
        package="ros_gz_sim",
        executable="create",
        arguments=["-name", "agv", "-file",
                   os.path.join(pkg, "models", "agv", "model.sdf"),
                   "-x", "0", "-y", "0", "-z", "0.2"],
        output="screen",
    )

    bridge = Node(
        package="ros_gz_bridge",
        executable="parameter_bridge",
        parameters=[{"config_file": bridge_cfg}],
        output="screen",
    )

    return LaunchDescription([gz_sim, spawn, bridge])

运行方式：ros2 launch my_robot sim.launch.py。注意 create 节点必须在仿真器起来之后再执行，否则会报找不到世界。

示例三：桥接配置 YAML

- ros_topic_name: "/cmd_vel"
  gz_topic_name: "/model/agv/cmd_vel"
  ros_type_name: "geometry_msgs/msg/Twist"
  gz_type_name: "gz.msgs.Twist"
  direction: ROS_TO_GZ

- ros_topic_name: "/scan"
  gz_topic_name: "/model/agv/scan"
  ros_type_name: "sensor_msgs/msg/LaserScan"
  gz_type_name: "gz.msgs.LaserScan"
  direction: GZ_TO_ROS

- ros_topic_name: "/clock"
  gz_topic_name: "/clock"
  ros_type_name: "rosgraph_msgs/msg/Clock"
  gz_type_name: "gz.msgs.Clock"
  direction: GZ_TO_ROS

方向写反是桥接最常见的问题：结果就是 ROS2 侧发了指令但车不动，或者传感器话题存在却一直没数据。类型名写错时桥接节点会在启动时直接报错，这类错误反而好查。

适合与不适合

• 适合：ROS2 系统的闭环验证、导航与 SLAM 调参、传感器布局验证、多机器人协同的大场景预演、CI 里跑回归测试。
• 不适合：需要照片级渲染或大量合成数据训练感知模型（用 Isaac Sim 一类）、接触丰富的精细操作（用 MuJoCo 一类）、对物理精度要求极高的受力分析（用专业多体动力学软件）。