ROS_URDF_Xacro惯性矩阵函数调用报错如何解决

在学习B站赵虚左主讲的ROS基础课程—— URDF 结合 Xacro 实操时，在一个xacro文件中调用了封装好的圆柱惯性矩阵函数，出现了如下错误：

代码如下：

xacro: Traditional processing is deprecated. Switch to --inorder processing!
To check for compatibility of your document, use option --check-order.
For more infos, see http://wiki.ros.org/xacro#Processing_Order
can't multiply sequence by non-int of type 'unicode' 
when evaluating expression 'm*(3*r*r + h*h) / 12'
when instantiating macro: cylinder_inertial_matrix (/home/qrx/catkin_ws/src/urdf02_gazebo/urdf/cylinder_test.urdf.xacro)
in file: /home/qrx/catkin_ws/src/urdf02_gazebo/urdf/cylinder_test.urdf.xacro
Invalid <param> tag: Cannot load command parameter [robot_description]: command [/opt/ros/kinetic/lib/xacro/xacro /home/qrx/catkin_ws/src/urdf02_gazebo/urdf/cylinder_test.urdf.xacro] returned with code [2]. 

Param xml is <param command="$(find xacro)/xacro $(find urdf02_gazebo)/urdf/cylinder_test.urdf.xacro" name="robot_description"/>
The traceback for the exception was written to the log file

惯性矩阵代码如下：

<robot name="base" xmlns:xacro="http://wiki.ros.org/xacro">
    <!-- Macro for inertia matrix -->
     <xacro:macro name="cylinder_inertial_matrix" params="m r h">
        <inertial>
            <mass value="${m}" />
            <inertia ixx="${m*(3*r*r+h*h)/12}" ixy = "0" ixz = "0"
                iyy="${m*(3*r*r+h*h)/12}" iyz = "0"
                izz="${m*r*r/2}" /> 
        </inertial>
    </xacro:macro>
</robot>

所编写的demo08_cylinder.urdf.xacro文件代码如下：

<robot name="cylinder_test" xmlns:xacro="http://wiki.ros.org/xacro">
    <xacro:property name="cylinder_radius" value="0.1"/>
    <xacro:property name="cylinder_length" value="1"/>
    <xacro:property name="cylinder_mass" value="1"/>

    <link name="cylinder_link">
        <visual>
            <geometry>
                <cylinder radius="cylinder_radius" length="cylinder_length"/>
            </geometry>
            <origin xyz="0.0 0.0 0.0" rpy="0.0 0.0 0.0"/>
            <material>
                <color rgba="0.3 0.3 0.6 1.0"/>
            </material>
        </visual>
        <collision>
            <geometry>
                <cylinder radius="cylinder_radius" length="cylinder_length"/>
            </geometry>
            <origin xyz="0.0 0.0 0.0" rpy="0.0 0.0 0.0"/>
        </collision>

        <xacro:cylinder_inertial_matrix m="cylinder_mass" r="cylinder_radius" h="cylinder_length"/>
        
    </link> 

    <gazebo reference="cylinder_link">
        <material>Gazebo/Blue</material>

    </gazebo>


</robot>

launch文件配置如下：

<launch>
<!-- 1.loanding attributes model in server -->
<param name="robot_description" command="$(find xacro)/xacro $(find urdf02_gazebo)/urdf/cylinder_test.urdf.xacro" />
<!-- 2.launch simulation environment -->
<include file="$(find gazebo_ros)/launch/empty_world.launch" />
<!-- 3. add robot model in Gazebo-->
<node pkg="gazebo_ros" type="spawn_model" name="spawn_model" args="-urdf -model cylinder_test -param robot_description" />

</launch>

由于测试文件与圆柱惯性矩阵函数是分开编写，所以需要包含一下，代码如下：

<robot name="cylinder_test" xmlns:xacro="http://wiki.ros.org/xacro">
     <!-- include inertil matrix file -->
    <xacro:include filename="head.urdf.xacro"/>
    
    <xacro:include filename="demo08_cylinder.urdf.xacro"/>
</robot>

我已经找了好几个论坛，ROS官方论坛也找了，但没有结果，希望各位能帮我解答一下，万分感谢
运行环境：VM Workstation + Linux Ubuntu 16.04
Ros 版本：kinetic
编程语言：Python 3.5.2
编辑器：VS code

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