fix "could not read robot_description parameter"

fd_bringup/launch/fd.launch.py

@@ -21,6 +21,7 @@
     PathJoinSubstitution,
 )
 from launch_ros.actions import Node
+from launch_ros.parameter_descriptions import ParameterValue
 from launch_ros.substitutions import FindPackageShare
 
 
@@ -46,7 +47,7 @@ def generate_launch_description():
             ' use_clutch:=', use_clutch,
         ]
     )
-    robot_description = {'robot_description': robot_description_content}
+    robot_description = {'robot_description': ParameterValue(robot_description_content, value_type=str)}
 
     phi_controllers = PathJoinSubstitution(
         [