[QUESTION] There is a small difference between generated URDF and provided Mujoco XML of OpenArm v1.0

[celestialdr4g0n]

I generated a URDF file from these ROS packages
https://github.com/enactic/openarm_ros2.git
https://github.com/enactic/openarm_description.git

Using this command

xacro ./openarm_description/urdf/robot/v10.urdf.xacro arm_type:=v10 bimanual:=true > openarm_bimanual.urdf

Bellow is the generated URDF

<?xml version="1.0" ?>
<!-- =================================================================================== -->
<!-- |    This document was autogenerated by xacro from ./openarm_description/urdf/robot/v10.urdf.xacro | -->
<!-- |    EDITING THIS FILE BY HAND IS NOT RECOMMENDED                                 | -->
<!-- =================================================================================== -->
<robot name="openarm">
  <!-- Is the robot being simulated in gazebo? -->
  <!-- <xacro:arg name="gazebo" default="false" /> -->
  <link name="world"/>
  <joint name="openarm_body_world_joint" type="fixed">
    <parent link="world"/>
    <child link="openarm_body_link0"/>
    <origin rpy="0 0 0" xyz="0 0 0"/>
  </joint>
  <link name="openarm_body_link0">
    <visual name="openarm_body_link0_visual">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 0.0 0.0"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/body/v10/visual/body_link0.dae" scale="0.001 0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_body_link0_collision">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 0.0 0.0"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/body/v10/collision/body_link0_symp.stl" scale="0.001 0.001 0.001"/>
        <!-- <mesh filename="package://openarm_description/meshes/arm/${arm_type}/collision/${name}.stl" scale="0.001 0.001 0.001" /> -->
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0.0 0.0 0.0" xyz="0.0 0.0 0.0"/>
      <mass value="13.89"/>
      <inertia ixx="1.653" ixy="0.0" ixz="0.0" iyy="1.653" iyz="0.0" izz="0.051"/>
    </inertial>
  </link>
  <joint name="openarm_left_openarm_body_link0_joint" type="fixed">
    <parent link="openarm_body_link0"/>
    <child link="openarm_left_link0"/>
    <origin rpy="-1.5708 0 0" xyz="0.0 0.031 0.698"/>
  </joint>
  <link name="openarm_left_link0">
    <visual name="openarm_left_link0_visual">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 0.0 0.0"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/visual/link0.dae" scale="0.001 -0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_left_link0_collision">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 0.0 0.0"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/collision/link0_symp.stl" scale="0.001 -0.001 0.001"/>
        <!-- <mesh filename="package://openarm_description/meshes/arm/${arm_type}/collision/${name}.stl" scale="0.001 0.001 0.001" /> -->
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0.0 0.0 0.0" xyz="-0.0009483362816297526 -0.0001580207020448382 0.03076860287587199"/>
      <mass value="1.1432284943239561"/>
      <inertia ixx="0.001128" ixy="-4e-06" ixz="-3.3e-05" iyy="0.000962" iyz="-7e-06" izz="0.00147"/>
    </inertial>
  </link>
  <link name="openarm_left_link1">
    <visual name="openarm_left_link1_visual">
      <origin rpy="0.0 0.0 0.0" xyz="-0.0 0.0 -0.0625"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/visual/link1.dae" scale="0.001 -0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_left_link1_collision">
      <origin rpy="0.0 0.0 0.0" xyz="-0.0 0.0 -0.0625"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/collision/link1_symp.stl" scale="0.001 -0.001 0.001"/>
        <!-- <mesh filename="package://openarm_description/meshes/arm/${arm_type}/collision/${name}.stl" scale="0.001 0.001 0.001" /> -->
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0.0 0.0 0.0" xyz="0.0011467657911800769 -3.319987657026362e-05 0.05395284380736254"/>
      <mass value="1.1416684646202298"/>
      <inertia ixx="0.001567" ixy="-1e-06" ixz="-2.9e-05" iyy="0.001273" iyz="1e-06" izz="0.001016"/>
    </inertial>
  </link>
  <joint name="openarm_left_joint1" type="revolute">
    <origin rpy="0 0 0" xyz="0.0 0.0 0.0625"/>
    <parent link="openarm_left_link0"/>
    <child link="openarm_left_link1"/>
    <axis xyz="0 0 1"/>
    <limit effort="40" lower="-3.490659" upper="1.3962629999999998" velocity="16.754666"/>
  </joint>
  <link name="openarm_left_link2">
    <visual name="openarm_left_link2_visual">
      <origin rpy="0.0 0.0 0.0" xyz="0.0301 0.0 -0.1225"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/visual/link2.dae" scale="0.001 -0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_left_link2_collision">
      <origin rpy="0.0 0.0 0.0" xyz="0.0301 0.0 -0.1225"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/collision/link2_symp.stl" scale="0.001 -0.001 0.001"/>
        <!-- <mesh filename="package://openarm_description/meshes/arm/${arm_type}/collision/${name}.stl" scale="0.001 0.001 0.001" /> -->
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0.0 0.0 0.0" xyz="0.00839629182351943 2.0145102027597523e-08 0.03256649300522363"/>
      <mass value="0.2775092746011571"/>
      <inertia ixx="0.000359" ixy="1e-06" ixz="-0.000109" iyy="0.000376" iyz="1e-06" izz="0.000232"/>
    </inertial>
  </link>
  <joint name="openarm_left_joint2" type="revolute">
    <origin rpy="-1.57079632679 0 0" xyz="-0.0301 0.0 0.06"/>
    <parent link="openarm_left_link1"/>
    <child link="openarm_left_link2"/>
    <axis xyz="-1 0 0"/>
    <limit effort="40" lower="-3.3161253267948965" upper="0.17453267320510335" velocity="16.754666"/>
  </joint>
  <link name="openarm_left_link3">
    <visual name="openarm_left_link3_visual">
      <origin rpy="0.0 0.0 0.0" xyz="-0.0 -0.0 -0.18875"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/visual/link3.dae" scale="0.001 -0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_left_link3_collision">
      <origin rpy="0.0 0.0 0.0" xyz="-0.0 -0.0 -0.18875"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/collision/link3_symp.stl" scale="0.001 -0.001 0.001"/>
        <!-- <mesh filename="package://openarm_description/meshes/arm/${arm_type}/collision/${name}.stl" scale="0.001 0.001 0.001" /> -->
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0.0 0.0 0.0" xyz="-0.002104752099628911 -0.0005549085042607548 0.09047470545721961"/>
      <mass value="1.073863338202347"/>
      <inertia ixx="0.004372" ixy="1e-06" ixz="1.1e-05" iyy="0.004319" iyz="-3.6e-05" izz="0.000661"/>
    </inertial>
  </link>
  <joint name="openarm_left_joint3" type="revolute">
    <origin rpy="0 0 0" xyz="0.0301 0.0 0.06625"/>
    <parent link="openarm_left_link2"/>
    <child link="openarm_left_link3"/>
    <axis xyz="0 0 1"/>
    <limit effort="27" lower="-1.570796" upper="1.570796" velocity="5.445426"/>
  </joint>
  <link name="openarm_left_link4">
    <visual name="openarm_left_link4_visual">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 -0.0315 -0.3425"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/visual/link4.dae" scale="0.001 0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_left_link4_collision">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 -0.0315 -0.3425"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/collision/link4_symp.stl" scale="0.001 0.001 0.001"/>
        <!-- <mesh filename="package://openarm_description/meshes/arm/${arm_type}/collision/${name}.stl" scale="0.001 0.001 0.001" /> -->
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0.0 0.0 0.0" xyz="-0.0029006831074562967 -0.03030575826634669 0.06339637422196209"/>
      <mass value="0.6348534566833373"/>
      <inertia ixx="0.000623" ixy="-1e-06" ixz="-1.9e-05" iyy="0.000511" iyz="3.8e-05" izz="0.000334"/>
    </inertial>
  </link>
  <joint name="openarm_left_joint4" type="revolute">
    <origin rpy="0 0 0" xyz="-0.0 0.0315 0.15375"/>
    <parent link="openarm_left_link3"/>
    <child link="openarm_left_link4"/>
    <axis xyz="0 1 0"/>
    <limit effort="27" lower="0.0" upper="2.443461" velocity="5.445426"/>
  </joint>
  <link name="openarm_left_link5">
    <visual name="openarm_left_link5_visual">
      <origin rpy="0.0 0.0 0.0" xyz="-0.0 -0.0 -0.438"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/visual/link5.dae" scale="0.001 -0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_left_link5_collision">
      <origin rpy="0.0 0.0 0.0" xyz="-0.0 -0.0 -0.438"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/collision/link5_symp.stl" scale="0.001 -0.001 0.001"/>
        <!-- <mesh filename="package://openarm_description/meshes/arm/${arm_type}/collision/${name}.stl" scale="0.001 0.001 0.001" /> -->
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0.0 0.0 0.0" xyz="-0.003049665024221911 -0.0008866902457326625 0.043079803024980934"/>
      <mass value="0.6156588026168502"/>
      <inertia ixx="0.000423" ixy="-8e-06" ixz="6e-06" iyy="0.000445" iyz="-6e-06" izz="0.000324"/>
    </inertial>
  </link>
  <joint name="openarm_left_joint5" type="revolute">
    <origin rpy="0 0 0" xyz="0.0 -0.0315 0.0955"/>
    <parent link="openarm_left_link4"/>
    <child link="openarm_left_link5"/>
    <axis xyz="0 0 1"/>
    <limit effort="7" lower="-1.570796" upper="1.570796" velocity="20.943946"/>
  </joint>
  <link name="openarm_left_link6">
    <visual name="openarm_left_link6_visual">
      <origin rpy="0.0 0.0 0.0" xyz="-0.0375 -0.0 -0.5585"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/visual/link6.dae" scale="0.001 -0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_left_link6_collision">
      <origin rpy="0.0 0.0 0.0" xyz="-0.0375 -0.0 -0.5585"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/collision/link6_symp.stl" scale="0.001 -0.001 0.001"/>
        <!-- <mesh filename="package://openarm_description/meshes/arm/${arm_type}/collision/${name}.stl" scale="0.001 0.001 0.001" /> -->
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0.0 0.0 0.0" xyz="-0.037136587005447405 -0.00033230528343419053 -9.498374522309838e-05"/>
      <mass value="0.475202773187987"/>
      <inertia ixx="0.000143" ixy="1e-06" ixz="1e-06" iyy="0.000157" iyz="1e-06" izz="0.000159"/>
    </inertial>
  </link>
  <joint name="openarm_left_joint6" type="revolute">
    <origin rpy="0 0 0" xyz="0.0375 0.0 0.1205"/>
    <parent link="openarm_left_link5"/>
    <child link="openarm_left_link6"/>
    <axis xyz="1 0 0"/>
    <limit effort="7" lower="-0.785398" upper="0.785398" velocity="20.943946"/>
  </joint>
  <link name="openarm_left_link7">
    <visual name="openarm_left_link7_visual">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 -0.0 -0.5585"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/visual/link7.dae" scale="0.001 -0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_left_link7_collision">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 -0.0 -0.5585"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/collision/link7_symp.stl" scale="0.001 -0.001 0.001"/>
        <!-- <mesh filename="package://openarm_description/meshes/arm/${arm_type}/collision/${name}.stl" scale="0.001 0.001 0.001" /> -->
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0.0 0.0 0.0" xyz="6.875510271106056e-05 -0.01266175250761268 0.06951945409987448"/>
      <mass value="0.4659771327380578"/>
      <inertia ixx="0.000639" ixy="1e-06" ixz="1e-06" iyy="0.000497" iyz="8.9e-05" izz="0.000342"/>
    </inertial>
  </link>
  <joint name="openarm_left_joint7" type="revolute">
    <origin rpy="0 0 0" xyz="-0.0375 0.0 0.0"/>
    <parent link="openarm_left_link6"/>
    <child link="openarm_left_link7"/>
    <axis xyz="0 -1 0"/>
    <limit effort="7" lower="-1.570796" upper="1.570796" velocity="20.943946"/>
  </joint>
  <!-- <link name="${prefix}link8"/>

    <joint name="${prefix}joint8" type="fixed">
      <xacro:openarm-kinematics name="joint8" config="${kinematics}" />
      <parent link="${prefix}link7" />
      <child link="${prefix}link8" />
    </joint> -->
  <joint name="openarm_right_openarm_body_link0_joint" type="fixed">
    <parent link="openarm_body_link0"/>
    <child link="openarm_right_link0"/>
    <origin rpy="1.5708 0 0" xyz="0.0 -0.031 0.698"/>
  </joint>
  <link name="openarm_right_link0">
    <visual name="openarm_right_link0_visual">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 0.0 0.0"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/visual/link0.dae" scale="0.001 0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_right_link0_collision">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 0.0 0.0"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/collision/link0_symp.stl" scale="0.001 0.001 0.001"/>
        <!-- <mesh filename="package://openarm_description/meshes/arm/${arm_type}/collision/${name}.stl" scale="0.001 0.001 0.001" /> -->
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0.0 0.0 0.0" xyz="-0.0009483362816297526 0.0001580207020448382 0.03076860287587199"/>
      <mass value="1.1432284943239561"/>
      <inertia ixx="0.001128" ixy="-4e-06" ixz="-3.3e-05" iyy="0.000962" iyz="-7e-06" izz="0.00147"/>
    </inertial>
  </link>
  <link name="openarm_right_link1">
    <visual name="openarm_right_link1_visual">
      <origin rpy="0.0 0.0 0.0" xyz="-0.0 0.0 -0.0625"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/visual/link1.dae" scale="0.001 0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_right_link1_collision">
      <origin rpy="0.0 0.0 0.0" xyz="-0.0 0.0 -0.0625"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/collision/link1_symp.stl" scale="0.001 0.001 0.001"/>
        <!-- <mesh filename="package://openarm_description/meshes/arm/${arm_type}/collision/${name}.stl" scale="0.001 0.001 0.001" /> -->
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0.0 0.0 0.0" xyz="0.0011467657911800769 3.319987657026362e-05 0.05395284380736254"/>
      <mass value="1.1416684646202298"/>
      <inertia ixx="0.001567" ixy="-1e-06" ixz="-2.9e-05" iyy="0.001273" iyz="1e-06" izz="0.001016"/>
    </inertial>
  </link>
  <joint name="openarm_right_joint1" type="revolute">
    <origin rpy="0 0 0" xyz="0.0 0.0 0.0625"/>
    <parent link="openarm_right_link0"/>
    <child link="openarm_right_link1"/>
    <axis xyz="0 0 1"/>
    <limit effort="40" lower="-1.396263" upper="3.490659" velocity="16.754666"/>
  </joint>
  <link name="openarm_right_link2">
    <visual name="openarm_right_link2_visual">
      <origin rpy="0.0 0.0 0.0" xyz="0.0301 0.0 -0.1225"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/visual/link2.dae" scale="0.001 0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_right_link2_collision">
      <origin rpy="0.0 0.0 0.0" xyz="0.0301 0.0 -0.1225"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/collision/link2_symp.stl" scale="0.001 0.001 0.001"/>
        <!-- <mesh filename="package://openarm_description/meshes/arm/${arm_type}/collision/${name}.stl" scale="0.001 0.001 0.001" /> -->
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0.0 0.0 0.0" xyz="0.00839629182351943 -2.0145102027597523e-08 0.03256649300522363"/>
      <mass value="0.2775092746011571"/>
      <inertia ixx="0.000359" ixy="1e-06" ixz="-0.000109" iyy="0.000376" iyz="1e-06" izz="0.000232"/>
    </inertial>
  </link>
  <joint name="openarm_right_joint2" type="revolute">
    <origin rpy="1.57079632679 0 0" xyz="-0.0301 0.0 0.06"/>
    <parent link="openarm_right_link1"/>
    <child link="openarm_right_link2"/>
    <axis xyz="-1 0 0"/>
    <limit effort="40" lower="-0.17453267320510335" upper="3.3161253267948965" velocity="16.754666"/>
  </joint>
  <link name="openarm_right_link3">
    <visual name="openarm_right_link3_visual">
      <origin rpy="0.0 0.0 0.0" xyz="-0.0 -0.0 -0.18875"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/visual/link3.dae" scale="0.001 0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_right_link3_collision">
      <origin rpy="0.0 0.0 0.0" xyz="-0.0 -0.0 -0.18875"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/collision/link3_symp.stl" scale="0.001 0.001 0.001"/>
        <!-- <mesh filename="package://openarm_description/meshes/arm/${arm_type}/collision/${name}.stl" scale="0.001 0.001 0.001" /> -->
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0.0 0.0 0.0" xyz="-0.002104752099628911 0.0005549085042607548 0.09047470545721961"/>
      <mass value="1.073863338202347"/>
      <inertia ixx="0.004372" ixy="1e-06" ixz="1.1e-05" iyy="0.004319" iyz="-3.6e-05" izz="0.000661"/>
    </inertial>
  </link>
  <joint name="openarm_right_joint3" type="revolute">
    <origin rpy="0 0 0" xyz="0.0301 0.0 0.06625"/>
    <parent link="openarm_right_link2"/>
    <child link="openarm_right_link3"/>
    <axis xyz="0 0 1"/>
    <limit effort="27" lower="-1.570796" upper="1.570796" velocity="5.445426"/>
  </joint>
  <link name="openarm_right_link4">
    <visual name="openarm_right_link4_visual">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 -0.0315 -0.3425"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/visual/link4.dae" scale="0.001 0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_right_link4_collision">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 -0.0315 -0.3425"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/collision/link4_symp.stl" scale="0.001 0.001 0.001"/>
        <!-- <mesh filename="package://openarm_description/meshes/arm/${arm_type}/collision/${name}.stl" scale="0.001 0.001 0.001" /> -->
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0.0 0.0 0.0" xyz="-0.0029006831074562967 -0.03030575826634669 0.06339637422196209"/>
      <mass value="0.6348534566833373"/>
      <inertia ixx="0.000623" ixy="-1e-06" ixz="-1.9e-05" iyy="0.000511" iyz="3.8e-05" izz="0.000334"/>
    </inertial>
  </link>
  <joint name="openarm_right_joint4" type="revolute">
    <origin rpy="0 0 0" xyz="-0.0 0.0315 0.15375"/>
    <parent link="openarm_right_link3"/>
    <child link="openarm_right_link4"/>
    <axis xyz="0 1 0"/>
    <limit effort="27" lower="0.0" upper="2.443461" velocity="5.445426"/>
  </joint>
  <link name="openarm_right_link5">
    <visual name="openarm_right_link5_visual">
      <origin rpy="0.0 0.0 0.0" xyz="-0.0 -0.0 -0.438"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/visual/link5.dae" scale="0.001 0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_right_link5_collision">
      <origin rpy="0.0 0.0 0.0" xyz="-0.0 -0.0 -0.438"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/collision/link5_symp.stl" scale="0.001 0.001 0.001"/>
        <!-- <mesh filename="package://openarm_description/meshes/arm/${arm_type}/collision/${name}.stl" scale="0.001 0.001 0.001" /> -->
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0.0 0.0 0.0" xyz="-0.003049665024221911 0.0008866902457326625 0.043079803024980934"/>
      <mass value="0.6156588026168502"/>
      <inertia ixx="0.000423" ixy="-8e-06" ixz="6e-06" iyy="0.000445" iyz="-6e-06" izz="0.000324"/>
    </inertial>
  </link>
  <joint name="openarm_right_joint5" type="revolute">
    <origin rpy="0 0 0" xyz="0.0 -0.0315 0.0955"/>
    <parent link="openarm_right_link4"/>
    <child link="openarm_right_link5"/>
    <axis xyz="0 0 1"/>
    <limit effort="7" lower="-1.570796" upper="1.570796" velocity="20.943946"/>
  </joint>
  <link name="openarm_right_link6">
    <visual name="openarm_right_link6_visual">
      <origin rpy="0.0 0.0 0.0" xyz="-0.0375 -0.0 -0.5585"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/visual/link6.dae" scale="0.001 0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_right_link6_collision">
      <origin rpy="0.0 0.0 0.0" xyz="-0.0375 -0.0 -0.5585"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/collision/link6_symp.stl" scale="0.001 0.001 0.001"/>
        <!-- <mesh filename="package://openarm_description/meshes/arm/${arm_type}/collision/${name}.stl" scale="0.001 0.001 0.001" /> -->
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0.0 0.0 0.0" xyz="-0.037136587005447405 0.00033230528343419053 -9.498374522309838e-05"/>
      <mass value="0.475202773187987"/>
      <inertia ixx="0.000143" ixy="1e-06" ixz="1e-06" iyy="0.000157" iyz="1e-06" izz="0.000159"/>
    </inertial>
  </link>
  <joint name="openarm_right_joint6" type="revolute">
    <origin rpy="0 0 0" xyz="0.0375 0.0 0.1205"/>
    <parent link="openarm_right_link5"/>
    <child link="openarm_right_link6"/>
    <axis xyz="1 0 0"/>
    <limit effort="7" lower="-0.785398" upper="0.785398" velocity="20.943946"/>
  </joint>
  <link name="openarm_right_link7">
    <visual name="openarm_right_link7_visual">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 -0.0 -0.5585"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/visual/link7.dae" scale="0.001 0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_right_link7_collision">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 -0.0 -0.5585"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/arm/v10/collision/link7_symp.stl" scale="0.001 0.001 0.001"/>
        <!-- <mesh filename="package://openarm_description/meshes/arm/${arm_type}/collision/${name}.stl" scale="0.001 0.001 0.001" /> -->
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0.0 0.0 0.0" xyz="6.875510271106056e-05 0.01266175250761268 0.06951945409987448"/>
      <mass value="0.4659771327380578"/>
      <inertia ixx="0.000639" ixy="1e-06" ixz="1e-06" iyy="0.000497" iyz="8.9e-05" izz="0.000342"/>
    </inertial>
  </link>
  <joint name="openarm_right_joint7" type="revolute">
    <origin rpy="0 0 0" xyz="-0.0375 0.0 0.0"/>
    <parent link="openarm_right_link6"/>
    <child link="openarm_right_link7"/>
    <axis xyz="0 1 0"/>
    <limit effort="7" lower="-1.570796" upper="1.570796" velocity="20.943946"/>
  </joint>
  <!-- <link name="${prefix}link8"/>

    <joint name="${prefix}joint8" type="fixed">
      <xacro:openarm-kinematics name="joint8" config="${kinematics}" />
      <parent link="${prefix}link7" />
      <child link="${prefix}link8" />
    </joint> -->
  <link name="openarm_left_hand">
    <visual name="openarm_left_hand_visual">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 0.0 -0.6585"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/ee/openarm_hand/visual/hand.dae" scale="0.001 0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_left_hand_collision">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 0.0 -0.6585"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/ee/openarm_hand/collision/hand.stl" scale="0.001 0.001 0.001"/>
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0 0 0" xyz="0.0 0.002 0.03"/>
      <mass value="0.35"/>
      <inertia ixx="0.0002473" ixy="1e-06" ixz="1e-06" iyy="1.763e-05" iyz="1e-06" izz="0.0002521"/>
    </inertial>
  </link>
  <!-- <link name="${ee_prefix}hand"/> -->
  <!-- <joint name="${ee_prefix}hand_joint" type="fixed"> -->
  <joint name="left_openarm_hand_joint" type="fixed">
    <parent link="openarm_left_link7"/>
    <child link="openarm_left_hand"/>
    <origin rpy="0 0 0" xyz="0 -0.0 0.1001"/>
  </joint>
  <!-- Define the hand_tcp frame -->
  <link name="openarm_left_hand_tcp"/>
  <joint name="openarm_left_hand_tcp_joint" type="fixed">
    <origin rpy="0 0 0" xyz="0 -0.0 0.08"/>
    <parent link="openarm_left_hand"/>
    <child link="openarm_left_hand_tcp"/>
  </joint>
  <link name="openarm_left_left_finger">
    <visual name="openarm_left_left_finger_visual">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 -0.05 -0.673001"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/ee/openarm_hand/visual/finger.dae" scale="0.001 0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_left_left_finger_collision">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 -0.05 -0.673001"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/ee/openarm_hand/collision/finger.stl" scale="0.001 0.001 0.001"/>
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0 0 0" xyz="0.0064528 0.01702 0.0219685"/>
      <mass value="0.03602545343277134"/>
      <inertia ixx="2.3749999999999997e-06" ixy="1e-06" ixz="1e-06" iyy="2.3749999999999997e-06" iyz="1e-06" izz="7.5e-07"/>
    </inertial>
  </link>
  <link name="openarm_left_right_finger">
    <visual name="openarm_left_right_finger_visual">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 0.05 -0.673001"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/ee/openarm_hand/visual/finger.dae" scale="0.001 -0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_left_right_finger_collision">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 0.05 -0.673001"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/ee/openarm_hand/collision/finger.stl" scale="0.001 -0.001 0.001"/>
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0 0 0" xyz="0.0064528 -0.01702 0.0219685"/>
      <mass value="0.03602545343277134"/>
      <inertia ixx="2.3749999999999997e-06" ixy="1e-06" ixz="1e-06" iyy="2.3749999999999997e-06" iyz="1e-06" izz="7.5e-07"/>
    </inertial>
  </link>
  <joint name="openarm_left_finger_joint1" type="prismatic">
    <parent link="openarm_left_hand"/>
    <child link="openarm_left_right_finger"/>
    <origin rpy="0 0 0" xyz="0 -0.006 0.015"/>
    <axis xyz="0 -1 0"/>
    <limit effort="333" lower="0.0" upper="0.044" velocity="10.0"/>
  </joint>
  <joint name="openarm_left_finger_joint2" type="prismatic">
    <parent link="openarm_left_hand"/>
    <child link="openarm_left_left_finger"/>
    <origin rpy="0 0 0" xyz="0 0.006 0.015"/>
    <axis xyz="0 1 0"/>
    <limit effort="333" lower="0.0" upper="0.044" velocity="10.0"/>
    <mimic joint="openarm_left_finger_joint1"/>
  </joint>
  <link name="openarm_right_hand">
    <visual name="openarm_right_hand_visual">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 0.0 -0.6585"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/ee/openarm_hand/visual/hand.dae" scale="0.001 0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_right_hand_collision">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 0.0 -0.6585"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/ee/openarm_hand/collision/hand.stl" scale="0.001 0.001 0.001"/>
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0 0 0" xyz="0.0 0.002 0.03"/>
      <mass value="0.35"/>
      <inertia ixx="0.0002473" ixy="1e-06" ixz="1e-06" iyy="1.763e-05" iyz="1e-06" izz="0.0002521"/>
    </inertial>
  </link>
  <!-- <link name="${ee_prefix}hand"/> -->
  <!-- <joint name="${ee_prefix}hand_joint" type="fixed"> -->
  <joint name="right_openarm_hand_joint" type="fixed">
    <parent link="openarm_right_link7"/>
    <child link="openarm_right_hand"/>
    <origin rpy="0 0 0" xyz="0 -0.0 0.1001"/>
  </joint>
  <!-- Define the hand_tcp frame -->
  <link name="openarm_right_hand_tcp"/>
  <joint name="openarm_right_hand_tcp_joint" type="fixed">
    <origin rpy="0 0 0" xyz="0 -0.0 0.08"/>
    <parent link="openarm_right_hand"/>
    <child link="openarm_right_hand_tcp"/>
  </joint>
  <link name="openarm_right_left_finger">
    <visual name="openarm_right_left_finger_visual">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 -0.05 -0.673001"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/ee/openarm_hand/visual/finger.dae" scale="0.001 0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_right_left_finger_collision">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 -0.05 -0.673001"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/ee/openarm_hand/collision/finger.stl" scale="0.001 0.001 0.001"/>
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0 0 0" xyz="0.0064528 0.01702 0.0219685"/>
      <mass value="0.03602545343277134"/>
      <inertia ixx="2.3749999999999997e-06" ixy="1e-06" ixz="1e-06" iyy="2.3749999999999997e-06" iyz="1e-06" izz="7.5e-07"/>
    </inertial>
  </link>
  <link name="openarm_right_right_finger">
    <visual name="openarm_right_right_finger_visual">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 0.05 -0.673001"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/ee/openarm_hand/visual/finger.dae" scale="0.001 -0.001 0.001"/>
      </geometry>
    </visual>
    <collision name="openarm_right_right_finger_collision">
      <origin rpy="0.0 0.0 0.0" xyz="0.0 0.05 -0.673001"/>
      <geometry>
        <mesh filename="package://openarm_description/meshes/ee/openarm_hand/collision/finger.stl" scale="0.001 -0.001 0.001"/>
      </geometry>
    </collision>
    <inertial>
      <origin rpy="0 0 0" xyz="0.0064528 -0.01702 0.0219685"/>
      <mass value="0.03602545343277134"/>
      <inertia ixx="2.3749999999999997e-06" ixy="1e-06" ixz="1e-06" iyy="2.3749999999999997e-06" iyz="1e-06" izz="7.5e-07"/>
    </inertial>
  </link>
  <joint name="openarm_right_finger_joint1" type="prismatic">
    <parent link="openarm_right_hand"/>
    <child link="openarm_right_right_finger"/>
    <origin rpy="0 0 0" xyz="0 -0.006 0.015"/>
    <axis xyz="0 -1 0"/>
    <limit effort="333" lower="0.0" upper="0.044" velocity="10.0"/>
  </joint>
  <joint name="openarm_right_finger_joint2" type="prismatic">
    <parent link="openarm_right_hand"/>
    <child link="openarm_right_left_finger"/>
    <origin rpy="0 0 0" xyz="0 0.006 0.015"/>
    <axis xyz="0 1 0"/>
    <limit effort="333" lower="0.0" upper="0.044" velocity="10.0"/>
    <mimic joint="openarm_right_finger_joint1"/>
  </joint>
</robot>

Compared to this mujoco XML file for v1 at https://github.com/enactic/openarm_mujoco, openarm_left_link8 is commented out in the generated URDF. I am using https://github.com/stack-of-tasks/pinocchio as an IK solver and it requires a URDF of the OpenArm.

Will the difference have any impact on the result of the IK solver?

[Maaz-qureshi98]

Short answer: dropping link8 itself doesn't change the IK, but at the time it hid a ~4.5 mm offset between the URDF and the MuJoCo model's end-effector. The current versions of both repos no longer have that difference.

What link8 was

In openarm_description at the time of your post, link8 was a massless frame on a fixed joint after joint7 (commented out in urdf/arm/openarm_arm.xacro). It had no DoF and no inertia, so Pinocchio's model has the same 7 joints with or without it. The joint-space solution is identical, and you only lose one frame you could target.

Where the real difference was

Your target frame, the hand or TCP, didn't sit at the same pose in both models:

• MuJoCo v1 (openarm_mujoco): link7 → link8 (1e-6, 0.0205, 0) → hand (0, -0.025, 0.1001) → tcp (0, 0, 0.08), so the TCP sits at (0, −0.0045, 0.1801) in link7
• URDF (openarm_hand_arguments.xacro defaults): link7 → hand (0, 0, 0.1001) → tcp (0, 0, 0.08), so the TCP sits at (0, 0, 0.1801) in link7

That's a 4.5 mm offset along link7's y-axis. It rotates with the wrist, so IK solutions from the URDF land about 4.5 mm off when replayed in that MuJoCo model. It's small for most grasps, but it shows up in precise insertion or contact tasks.

What to do now

Both repos have since been aligned. openarm_description now attaches the hand 100.1 mm from link7 (enactic/openarm_description#91), and openarm_mujoco v1/ attaches openarm_left_hand directly to link7 at (0, 0, 0.1001). If you regenerate the URDF from the current main and use the current MJCF, the TCPs match.

If you're pinned to the older versions, either add the fixed frame back in your URDF (link7 → (0, -0.0045, 0.1001)) or solve IK for a TCP frame you define yourself, and use the same definition in both simulators.