facing problems with launch file

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I am a beginner, I am trying to launch a URDF file in rviz with the following code :

launch file code :

<launch>

<arg name="model" />


<param name="robot_description" textfile="$(find robot_description)/urdf/final_arm.urdf" />

<param name="use_gui" value="true"/>

<node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher" />

<node name="robot_state_publisher" pkg="robot_state_publisher" type="state_publisher" />

<node name="rviz" pkg="rviz" type="rviz" args="-d $(find robot_description)/urdf.rviz" required="true" />

</launch>

urdf file code (final_arm.urdf) :

<?xml version="1.0"?>
<robot name="ARM">

<link name="base_link">
      <visual>
        <origin rpy="0 0 0" xyz="0 0 0"/>
        <geometry>
          <mesh filename="package://robot_description/meshes/base_link.dae"/>
        </geometry>
      </visual>

      <inertial>
      <mass value="1"/>
      <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
      </inertial>
</link>


     <joint name="base_joint" type="revolute">
       <parent link="base_link"/>
       <child link="shoulder_link"/>
       <origin xyz="0 0 0"/>
       <axis xyz="0 0 1" />
       <limit effort="300" velocity="0.1" lower="-3.14" upper="3.14"/>
       <dynamics damping="50" friction="1"/>
     </joint>

<link name="shoulder_link">
      <visual>
        <origin rpy="0 0 0" xyz="0 0 0"/>
        <geometry>
          <mesh filename="package://robot_description/meshes/shoulder_link.dae"/>
        </geometry>
      </visual>
      <inertial>
      <mass value="1"/>
      <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0"izz="1.0"/>
      </inertial>
</link>


<joint name="shoulder_joint" type="revolute">
       <parent link="shoulder_link"/>
       <child link="elbo_link"/>
       <origin xyz="-0.385379 0.00451305 0.398126"/>
       <axis xyz="0 1 0" />
       <limit effort="300" velocity="0.1" lower="-3.14" upper="3.14"/>
       <dynamics damping="50" friction="1"/>
     </joint>


<link name="elbo_link">
      <visual>
        <origin rpy="0 0 0" xyz="0 0 0"/>
        <geometry>
          <mesh filename="package://robot_description/meshes/elbo_link.dae"/>
        </geometry>
      </visual>
      <inertial>
      <mass value="1"/>
      <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0"izz="1.0"/>
      </inertial>
</link>


<joint name="elbo_joint" type="revolute">
       <parent link="elbo_link"/>
       <child link="wrist_link"/>
       <origin xyz="-0.692963 0.022576 0.569845"/>
       <axis xyz="0 1 0" />
       <limit effort="300" velocity="0.1" lower="-3.14" upper="3.14"/>
       <dynamics damping="50" friction="1"/>
     </joint>



<link name="wrist_link">
      <visual>
        <origin rpy="0 0 0" xyz="0 0 0"/>
        <geometry>
          <mesh filename="package://robot_description/meshes/wrist_link.dae"/>
        </geometry>
      </visual>
      <inertial>
      <mass value="1"/>
      <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0"izz="1.0"/>
      </inertial>
</link>

<joint name="wrist_joint" type="revolute">
       <parent link="wrist_link"/>
       <child link="wrist2_link"/>
       <origin xyz="-0.580553 -0.720985 0.109695"/>
       <axis xyz="0 1 0" />
       <limit effort="300" velocity="0.1" lower="-3.14" upper="3.14"/>
       <dynamics damping="50" friction="1"/>
  </joint>


<link name="wrist2_link">
      <visual>
        <origin rpy="0 0 0" xyz="0 0 0"/>
        <geometry>
          <mesh filename="package://robot_description/meshes/wrist2_link.dae"/>
        </geometry>
      </visual>
      <inertial>
      <mass value="1"/>
      <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0"izz="1.0"/>
      </inertial>
</link>

<joint name="wrist2_joint" type="revolute">
       <parent link="wrist2_link"/>
       <child link="wrist3_link"/>
       <origin xyz="0 ...