BenBenBotKernal/Software/ROS_Driver/ROS1-driver/hoverboard_driver/launch/4x4.launch

<launch>
    <group ns="front">
        <param name="port" type="str" value="/dev/ttyTHS1"/>
        <include file="$(find hoverboard_driver)/launch/hoverboard.launch" />
    </group>
    <group ns="rear">
        <param name="port" type="str" value="/dev/ttyTHS2"/>
        <include file="$(find hoverboard_driver)/launch/hoverboard.launch" />
    </group>
</launch>