@小鱼 /您好，我也遇到了同样的问题，我的launch文件是：
from launch import LaunchDescription
from launch.substitutions import EnvironmentVariable
import launch.actions
import launch_ros.actions

def generate_launch_description():
use_sim_time = launch.substitutions.LaunchConfiguration('use_sim_time', default='true')
return LaunchDescription([
launch_ros.actions.Node(
package='slam_gmapping', node_executable='slam_gmapping', output='screen', parameters=[{'use_sim_time':use_sim_time}]),
])
请您帮我检查是否存在致命错误