diff --git a/examples/pybullet/gym/pybullet_data/quadruped/spirit40newer.urdf b/examples/pybullet/gym/pybullet_data/quadruped/spirit40newer.urdf
new file mode 100644
index 000000000..c93b6fd9e
--- /dev/null
+++ b/examples/pybullet/gym/pybullet_data/quadruped/spirit40newer.urdf
@@ -0,0 +1,598 @@
+<?xml version="1.0" ?>
+<robot name="a1_description" xmlns:xacro="http://www.ros.org/wiki/xacro">
+  <material name="black">
+    <color rgba="0.0 0.0 0.0 1.0"/>
+  </material>
+  <material name="blue">
+    <color rgba="0.0 0.0 0.8 1.0"/>
+  </material>
+  <material name="green">
+    <color rgba="0.0 0.8 0.0 1.0"/>
+  </material>
+  <material name="grey">
+    <color rgba="0.2 0.2 0.2 1.0"/>
+  </material>
+  <material name="silver">
+    <color rgba="0.913725490196 0.913725490196 0.847058823529 1.0"/>
+  </material>
+  <material name="orange">
+    <color rgba="1.0 0.423529411765 0.0392156862745 1.0"/>
+  </material>
+  <material name="brown">
+    <color rgba="0.870588235294 0.811764705882 0.764705882353 1.0"/>
+  </material>
+  <material name="red">
+    <color rgba="0.8 0.0 0.0 1.0"/>
+  </material>
+  <material name="white">
+    <color rgba="1.0 1.0 1.0 1.0"/>
+  </material>
+  <link name="trunk">
+    <visual>
+      <origin rpy="0 0 0" xyz="0 0 0"/>
+      <geometry>
+        <box size="0.335 0.24 0.104"/>
+      </geometry>
+      <material name="grey"/>
+    </visual>
+    <collision>
+      <origin rpy="0 0 0" xyz="0 0 0"/>
+      <geometry>
+        <box size="0.335 0.24 0.104"/>
+      </geometry>
+    </collision>
+    <inertial>
+      <origin rpy="0 0 0" xyz="0 0 0"/>
+      <mass value="5.75"/>
+      <inertia ixx="0.01683993" ixy="8.3902e-05" ixz="0.000597679" iyy="0.056579028" iyz="2.5134e-05" izz="0.064713601"/>
+    </inertial>
+  </link>
+ 
+  <joint name="FR_hip_joint" type="revolute">
+    <origin rpy="0 0 0" xyz="0.2263 -0.07 0"/>
+    <parent link="trunk"/>
+    <child link="FR_hip"/>
+    <axis xyz="1 0 0"/>
+    <dynamics damping="0" friction="0"/>
+    <limit effort="20" lower="-0.707" upper="0.707" velocity="52.4"/>
+  </joint>
+  <link name="FR_hip">
+    <visual>
+      <origin rpy="1.57079632679 0 0" xyz="0 0 0"/>
+      <geometry>
+        <cylinder length="0.08" radius="0.055"/>
+      </geometry>
+      <material name="grey"/>
+    </visual>
+    <collision>
+      <origin rpy="1.57079632679 0 0" xyz="0 0 0"/>
+      <geometry>
+        <cylinder length="0.08" radius="0.055"/>
+      </geometry>
+    </collision>
+    <inertial>
+      <origin rpy="0 0 0" xyz="-0.003311 -0.000635 3.1e-05"/>
+      <mass value="0.575"/>
+      <inertia ixx="0.000469246" ixy="9.409e-06" ixz="-3.42e-07" iyy="0.00080749" iyz="4.66e-07" izz="0.000552929"/>
+    </inertial>
+  </link>
+  <joint name="FR_hip_fixed" type="fixed">
+    <origin rpy="0 0 0" xyz="0 -0.081 0"/>
+    <parent link="FR_hip"/>
+    <child link="FR_upper_shoulder"/>
+  </joint>
+  <!-- this link is only for collision -->
+  <link name="FR_upper_shoulder">
+    <collision>
+      <origin rpy="1.57079632679 0 0" xyz="0 0 0"/>
+      <geometry>
+        <cylinder length="0.032" radius="0.041"/>
+      </geometry>
+    </collision>
+  </link>
+  <joint name="FR_upper_joint" type="revolute">
+    <origin rpy="0 0 0" xyz="0 -0.08505 0"/>
+    <parent link="FR_hip"/>
+    <child link="FR_upper"/>
+    <axis xyz="0 1 0"/>
+    <dynamics damping="0" friction="0"/>
+    <limit effort="55" lower="-6.28318530718" upper="6.28318530718" velocity="28.6"/>
+  </joint>
+  <link name="FR_upper">
+    <visual>
+      <origin rpy="0 0 0" xyz="-0.103 -0.022 0"/>
+      <geometry>
+        <box size="0.206 0.022 0.055"/>
+      </geometry>
+      <material name="grey"/>
+    </visual>
+    <collision>
+      <origin rpy="0 0 0" xyz="-0.103 -0.022 0"/>
+      <geometry>
+        <box size="0.206 0.022 0.055"/>
+      </geometry>
+    </collision>
+    <inertial>
+      <origin rpy="0 0 0" xyz="-0.003237 0.022327 -0.027326"/>
+      <mass value="0.775"/>
+      <inertia ixx="0.005529065" ixy="-4.825e-06" ixz="0.000343869" iyy="0.005139339" iyz="-2.2448e-05" izz="0.001367788"/>
+    </inertial>
+  </link>
+  <joint name="FR_lower_joint" type="revolute">
+    <origin rpy="0 0 0" xyz="-0.206 0 0"/>
+    <parent link="FR_upper"/>
+    <child link="FR_lower"/>
+    <axis xyz="0 1 0"/>
+    <dynamics damping="0" friction="0"/>
+    <limit effort="55" lower="0" upper="3.14159265359" velocity="28.6"/>
+  </joint>
+  <link name="FR_lower">
+    <visual>
+      <origin rpy="0 1.5707963268 0" xyz="0.103 0 0"/>
+      <geometry>
+        <cylinder length="0.206" radius="0.013"/>
+      </geometry>
+      <material name="grey"/>
+    </visual>
+    <collision>
+      <origin rpy="0 1.5707963268 0" xyz="0.103 0 0"/>
+      <geometry>
+        <cylinder length="0.206" radius="0.013"/>
+      </geometry>
+    </collision>
+    <inertial>
+      <mass value="0.075"/>
+      <inertia ixx="5e-06" ixy="0" ixz="0" iyy="0.0001" iyz="0" izz="0.0001"/>
+    </inertial>
+  </link>
+  <joint name="FR_toe_fixed" type="fixed">
+     <origin xyz="0.206 0 -0.0"/>
+    <parent link="FR_lower"/>
+    <child link="FR_toe"/>
+  </joint>
+  <link name="FR_toe">
+    <visual>
+      <origin rpy="0 0 0" xyz="0 0 0"/>
+      <geometry>
+        <sphere radius="0.01"/>
+      </geometry>
+      <material name="white"/>
+    </visual>
+    <collision>
+      <origin rpy="0 0 0" xyz="0 0 0"/>
+      <geometry>
+        <sphere radius="0.02"/>
+      </geometry>
+    </collision>
+    <inertial>
+      <mass value="0.06"/>
+      <inertia ixx="9.6e-06" ixy="0.0" ixz="0.0" iyy="9.6e-06" iyz="0.0" izz="9.6e-06"/>
+    </inertial>
+  </link>
+  
+  <joint name="FL_hip_joint" type="revolute">
+    <origin rpy="0 0 0" xyz="0.2263 0.07 0"/>
+    <parent link="trunk"/>
+    <child link="FL_hip"/>
+    <axis xyz="1 0 0"/>
+    <dynamics damping="0" friction="0"/>
+    <limit effort="20" lower="-0.707" upper="0.707" velocity="52.4"/>
+  </joint>
+  <link name="FL_hip">
+    <visual>
+      <origin rpy="1.57079632679 0 0" xyz="0 0 0"/>
+      <geometry>
+        <cylinder length="0.08" radius="0.055"/>
+      </geometry>
+      <material name="red"/>
+    </visual>
+    <collision>
+      <origin rpy="1.57079632679 0 0" xyz="0 0 0"/>
+      <geometry>
+        <cylinder length="0.08" radius="0.055"/>
+      </geometry>
+    </collision>
+    <inertial>
+      <origin rpy="0 0 0" xyz="-0.003311 0.000635 3.1e-05"/>
+      <mass value="0.575"/>
+      <inertia ixx="0.000469246" ixy="-9.409e-06" ixz="-3.42e-07" iyy="0.00080749" iyz="-4.66e-07" izz="0.000552929"/>
+    </inertial>
+  </link>
+  <joint name="FL_hip_fixed" type="fixed">
+    <origin rpy="0 0 0" xyz="0 0.081 0"/>
+    <parent link="FL_hip"/>
+    <child link="FL_upper_shoulder"/>
+  </joint>
+  <!-- this link is only for collision -->
+  <link name="FL_upper_shoulder">
+    <collision>
+      <origin rpy="1.57079632679 0 0" xyz="0 0 0"/>
+      <geometry>
+        <cylinder length="0.032" radius="0.041"/>
+      </geometry>
+    </collision>
+  </link>
+  <joint name="FL_upper_joint" type="revolute">
+    <origin rpy="0 0 0" xyz="0 0.08505 0"/>
+    <parent link="FL_hip"/>
+    <child link="FL_upper"/>
+    <axis xyz="0 1 0"/>
+    <dynamics damping="0" friction="0"/>
+    <limit effort="55" lower="-6.28318530718" upper="6.28318530718" velocity="28.6"/>
+  </joint>
+  <link name="FL_upper">
+    <visual>
+      <origin rpy="0 0 0" xyz="-0.103 -0.022 0"/>
+      <geometry>
+        <box size="0.206 0.022 0.055"/>
+      </geometry>
+      <material name="blue"/>
+    </visual>
+    <collision>
+      <origin rpy="0 0 0" xyz="-0.103 -0.022 0"/>
+      <geometry>
+        <box size="0.206 0.022 0.055"/>
+      </geometry>
+    </collision>
+    <inertial>
+      <origin rpy="0 0 0" xyz="-0.003237 -0.022327 -0.027326"/>
+      <mass value="0.775"/>
+      <inertia ixx="0.005529065" ixy="4.825e-06" ixz="0.000343869" iyy="0.005139339" iyz="2.2448e-05" izz="0.001367788"/>
+    </inertial>
+  </link>
+  <joint name="FL_lower_joint" type="revolute">
+     <origin xyz="-0.206 0 0"/>
+    <parent link="FL_upper"/>
+    <child link="FL_lower"/>
+    <axis xyz="0 1 0"/>
+    <dynamics damping="0" friction="0"/>
+    <limit effort="55" lower="0" upper="3.14159265359" velocity="28.6"/>
+  </joint>
+  <link name="FL_lower">
+    <visual>
+      <origin rpy="0 1.5707963268 0" xyz="0.103 0 0"/>
+      <geometry>
+        <cylinder length="0.206" radius="0.013"/>
+      </geometry>
+      <material name="green"/>
+    </visual>
+    <collision>
+      <origin rpy="0 1.5707963268 0" xyz="0.103 0 0"/>
+      <geometry>
+        <cylinder length="0.206" radius="0.013"/>
+      </geometry>
+    </collision>
+    <inertial>
+      <mass value="0.075"/>
+      <inertia ixx="5e-06" ixy="0" ixz="0" iyy="0.0001" iyz="0" izz="0.0001"/>
+    </inertial>
+  </link>
+  <joint name="FL_toe_fixed" type="fixed">
+    <origin xyz="0.206 0 -0.0"/>
+    <parent link="FL_lower"/>
+    <child link="FL_toe"/>
+  </joint>
+  <link name="FL_toe">
+    <visual>
+      <origin rpy="0 0 0" xyz="0 0 0"/>
+      <geometry>
+        <sphere radius="0.01"/>
+      </geometry>
+      <material name="orange"/>
+    </visual>
+    <collision>
+      <origin rpy="0 0 0" xyz="0 0 0"/>
+      <geometry>
+        <sphere radius="0.02"/>
+      </geometry>
+    </collision>
+    <inertial>
+      <mass value="0.06"/>
+      <inertia ixx="9.6e-06" ixy="0.0" ixz="0.0" iyy="9.6e-06" iyz="0.0" izz="9.6e-06"/>
+    </inertial>
+  </link>
+  <transmission name="FL_hip_tran">
+    <type>transmission_interface/SimpleTransmission</type>
+    <joint name="FL_hip_joint">
+      <hardwareInterface>hardware_interface/EffortJointInterface</hardwareInterface>
+    </joint>
+    <actuator name="FL_hip_motor">
+      <hardwareInterface>hardware_interface/EffortJointInterface</hardwareInterface>
+      <mechanicalReduction>1</mechanicalReduction>
+    </actuator>
+  </transmission>
+  <transmission name="FL_upper_tran">
+    <type>transmission_interface/SimpleTransmission</type>
+    <joint name="FL_upper_joint">
+      <hardwareInterface>hardware_interface/EffortJointInterface</hardwareInterface>
+    </joint>
+    <actuator name="FL_upper_motor">
+      <hardwareInterface>hardware_interface/EffortJointInterface</hardwareInterface>
+      <mechanicalReduction>1</mechanicalReduction>
+    </actuator>
+  </transmission>
+  <transmission name="FL_lower_tran">
+    <type>transmission_interface/SimpleTransmission</type>
+    <joint name="FL_lower_joint">
+      <hardwareInterface>hardware_interface/EffortJointInterface</hardwareInterface>
+    </joint>
+    <actuator name="FL_lower_motor">
+      <hardwareInterface>hardware_interface/EffortJointInterface</hardwareInterface>
+      <mechanicalReduction>1</mechanicalReduction>
+    </actuator>
+  </transmission>
+  <joint name="RR_hip_joint" type="revolute">
+    <origin rpy="0 0 0" xyz="-0.2263 -0.07 0"/>
+    <parent link="trunk"/>
+    <child link="RR_hip"/>
+    <axis xyz="1 0 0"/>
+    <dynamics damping="0" friction="0"/>
+    <limit effort="20" lower="-0.707" upper="0.707" velocity="52.4"/>
+  </joint>
+  <link name="RR_hip">
+    <visual>
+      <origin rpy="1.57079632679 0 0" xyz="0 0 0"/>
+      <geometry>
+        <cylinder length="0.08" radius="0.055"/>
+      </geometry>
+      <material name="orange"/>
+    </visual>
+    <collision>
+      <origin rpy="1.57079632679 0 0" xyz="0 0 0"/>
+      <geometry>
+        <cylinder length="0.08" radius="0.055"/>
+      </geometry>
+    </collision>
+    <inertial>
+      <origin rpy="0 0 0" xyz="0.003311 -0.000635 3.1e-05"/>
+      <mass value="0.575"/>
+      <inertia ixx="0.000469246" ixy="-9.409e-06" ixz="3.42e-07" iyy="0.00080749" iyz="4.66e-07" izz="0.000552929"/>
+    </inertial>
+  </link>
+  <joint name="RR_hip_fixed" type="fixed">
+    <origin rpy="0 0 0" xyz="0 -0.081 0"/>
+    <parent link="RR_hip"/>
+    <child link="RR_upper_shoulder"/>
+  </joint>
+  <!-- this link is only for collision -->
+  <link name="RR_upper_shoulder">
+    <collision>
+      <origin rpy="1.57079632679 0 0" xyz="0 0 0"/>
+      <geometry>
+        <cylinder length="0.032" radius="0.041"/>
+      </geometry>
+    </collision>
+  </link>
+  <joint name="RR_upper_joint" type="revolute">
+    <origin rpy="0 0 0" xyz="0 -0.08505 0"/>
+    <parent link="RR_hip"/>
+    <child link="RR_upper"/>
+    <axis xyz="0 1 0"/>
+    <dynamics damping="0" friction="0"/>
+    <limit effort="55" lower="-6.28318530718" upper="6.28318530718" velocity="28.6"/>
+  </joint>
+  <link name="RR_upper">
+    <visual>
+      <origin rpy="0 0 0" xyz="-0.103 -0.022 0"/>
+      <geometry>
+        <box size="0.206 0.022 0.055"/>
+      </geometry>
+      <material name="grey"/>
+    </visual>
+    <collision>
+      <origin rpy="0 0 0" xyz="-0.103 -0.022 0"/>
+      <geometry>
+        <box size="0.206 0.022 0.055"/>
+      </geometry>
+    </collision>
+    <inertial>
+      <origin rpy="0 0 0" xyz="-0.003237 0.022327 -0.027326"/>
+      <mass value="0.775"/>
+      <inertia ixx="0.005529065" ixy="-4.825e-06" ixz="0.000343869" iyy="0.005139339" iyz="-2.2448e-05" izz="0.001367788"/>
+    </inertial>
+  </link>
+  <joint name="RR_lower_joint" type="revolute">
+    <origin rpy="0 0 0" xyz="-0.206 0 0"/>
+    <parent link="RR_upper"/>
+    <child link="RR_lower"/>
+    <axis xyz="0 1 0"/>
+    <dynamics damping="0" friction="0"/>
+    <limit effort="55" lower="0" upper="3.14159265359" velocity="28.6"/>
+  </joint>
+  <link name="RR_lower">
+    <visual>
+      <origin rpy="0 1.5707963268 0" xyz="0.103 0 0"/>
+      <geometry>
+        <cylinder length="0.206" radius="0.013"/>
+      </geometry>
+      <material name="darkgray"/>
+    </visual>
+    <collision>
+      <origin rpy="0 1.5707963268 0" xyz="0.103 0 0"/>
+      <geometry>
+        <cylinder length="0.206" radius="0.013"/>
+      </geometry>
+    </collision>
+    <inertial>
+      <mass value="0.075"/>
+      <inertia ixx="5e-06" ixy="0" ixz="0" iyy="0.0001" iyz="0" izz="0.0001"/>
+    </inertial>
+  </link>
+  <joint name="RR_toe_fixed" type="fixed">
+  <origin xyz="0.206 0 -0.0"/>
+    <parent link="RR_lower"/>
+    <child link="RR_toe"/>
+  </joint>
+  <link name="RR_toe">
+    <visual>
+      <origin rpy="0 0 0" xyz="0 0 0"/>
+      <geometry>
+        <sphere radius="0.01"/>
+      </geometry>
+      <material name="orange"/>
+    </visual>
+    <collision>
+      <origin rpy="0 0 0" xyz="0 0 0"/>
+      <geometry>
+        <sphere radius="0.02"/>
+      </geometry>
+    </collision>
+    <inertial>
+      <mass value="0.06"/>
+      <inertia ixx="9.6e-06" ixy="0.0" ixz="0.0" iyy="9.6e-06" iyz="0.0" izz="9.6e-06"/>
+    </inertial>
+  </link>
+  <transmission name="RR_hip_tran">
+    <type>transmission_interface/SimpleTransmission</type>
+    <joint name="RR_hip_joint">
+      <hardwareInterface>hardware_interface/EffortJointInterface</hardwareInterface>
+    </joint>
+    <actuator name="RR_hip_motor">
+      <hardwareInterface>hardware_interface/EffortJointInterface</hardwareInterface>
+      <mechanicalReduction>1</mechanicalReduction>
+    </actuator>
+  </transmission>
+  <transmission name="RR_upper_tran">
+    <type>transmission_interface/SimpleTransmission</type>
+    <joint name="RR_upper_joint">
+      <hardwareInterface>hardware_interface/EffortJointInterface</hardwareInterface>
+    </joint>
+    <actuator name="RR_upper_motor">
+      <hardwareInterface>hardware_interface/EffortJointInterface</hardwareInterface>
+      <mechanicalReduction>1</mechanicalReduction>
+    </actuator>
+  </transmission>
+  <transmission name="RR_lower_tran">
+    <type>transmission_interface/SimpleTransmission</type>
+    <joint name="RR_lower_joint">
+      <hardwareInterface>hardware_interface/EffortJointInterface</hardwareInterface>
+    </joint>
+    <actuator name="RR_lower_motor">
+      <hardwareInterface>hardware_interface/EffortJointInterface</hardwareInterface>
+      <mechanicalReduction>1</mechanicalReduction>
+    </actuator>
+  </transmission>
+  <joint name="RL_hip_joint" type="revolute">
+    <origin rpy="0 0 0" xyz="-0.2263 0.07 0"/>
+    <parent link="trunk"/>
+    <child link="RL_hip"/>
+    <axis xyz="1 0 0"/>
+    <dynamics damping="0" friction="0"/>
+    <limit effort="20" lower="-0.707" upper="0.707" velocity="52.4"/>
+  </joint>
+  <link name="RL_hip">
+    <visual>
+      <origin rpy="1.57079632679 0 0" xyz="0 0 0"/>
+      <geometry>
+        <cylinder length="0.08" radius="0.055"/>
+      </geometry>
+      <material name="orange"/>
+    </visual>
+    <collision>
+      <origin rpy="1.57079632679 0 0" xyz="0 0 0"/>
+      <geometry>
+        <cylinder length="0.08" radius="0.055"/>
+      </geometry>
+    </collision>
+    <inertial>
+      <origin rpy="0 0 0" xyz="0.003311 0.000635 3.1e-05"/>
+      <mass value="0.575"/>
+      <inertia ixx="0.000469246" ixy="9.409e-06" ixz="3.42e-07" iyy="0.00080749" iyz="-4.66e-07" izz="0.000552929"/>
+    </inertial>
+  </link>
+  <joint name="RL_hip_fixed" type="fixed">
+    <origin rpy="0 0 0" xyz="0 0.081 0"/>
+    <parent link="RL_hip"/>
+    <child link="RL_upper_shoulder"/>
+  </joint>
+  <!-- this link is only for collision -->
+  <link name="RL_upper_shoulder">
+    <collision>
+      <origin rpy="1.57079632679 0 0" xyz="0 0 0"/>
+      <geometry>
+        <cylinder length="0.032" radius="0.041"/>
+      </geometry>
+    </collision>
+  </link>
+  <joint name="RL_upper_joint" type="revolute">
+    <origin rpy="0 0 0" xyz="0 0.08505 0"/>
+    <parent link="RL_hip"/>
+    <child link="RL_upper"/>
+    <axis xyz="0 1 0"/>
+    <dynamics damping="0" friction="0"/>
+    <limit effort="55" lower="-6.28318530718" upper="6.28318530718" velocity="28.6"/>
+  </joint>
+  <link name="RL_upper">
+    <visual>
+      <origin rpy="0 0 0" xyz="-0.103 -0.022 0"/>
+      <geometry>
+        <box size="0.206 0.022 0.055"/>
+      </geometry>
+      <material name="grey"/>
+    </visual>
+    <collision>
+      <origin rpy="0 0 0" xyz="-0.103 -0.022 0"/>
+      <geometry>
+        <box size="0.206 0.022 0.055"/>
+      </geometry>
+    </collision>
+    <inertial>
+      <origin rpy="0 0 0" xyz="-0.003237 0.022327 -0.027326"/>
+      <mass value="0.775"/>
+      <inertia ixx="0.005529065" ixy="-4.825e-06" ixz="0.000343869" iyy="0.005139339" iyz="-2.2448e-05" izz="0.001367788"/>
+    </inertial>
+  </link>
+  <joint name="RL_lower_joint" type="revolute">
+    <axis xyz="0 1 0"/>
+    <origin xyz="-0.206 0 0"/>
+    <parent link="RL_upper"/>
+    <child link="RL_lower"/>
+    <axis xyz="0 1 0"/>
+    <dynamics damping="0" friction="0"/>
+    <limit effort="55" lower="0" upper="3.14159265359" velocity="28.6"/>
+  </joint>
+  <link name="RL_lower">
+     <visual>
+      <origin rpy="0 1.5707963268 0" xyz="0.103 0 0"/>
+      <geometry>
+        <cylinder length="0.206" radius="0.013"/>
+      </geometry>
+      <material name="darkgray"/>
+    </visual>
+    <collision>
+      <origin rpy="0 1.5707963268 0" xyz="0.103 0 0"/>
+      <geometry>
+        <cylinder length="0.206" radius="0.013"/>
+      </geometry>
+    </collision>
+    <inertial>
+      <mass value="0.075"/>
+      <inertia ixx="5e-06" ixy="0" ixz="0" iyy="0.0001" iyz="0" izz="0.0001"/>
+    </inertial>
+  </link>
+  <joint name="RL_toe_fixed" type="fixed">
+    <origin xyz="0.206 0 -0.0"/>
+    <parent link="RL_lower"/>
+    <child link="RL_toe"/>
+  </joint>
+  <link name="RL_toe">
+    <visual>
+      <origin rpy="0 0 0" xyz="0 0 0"/>
+      <geometry>
+        <sphere radius="0.01"/>
+      </geometry>
+      <material name="orange"/>
+    </visual>
+    <collision>
+      <origin rpy="0 0 0" xyz="0 0 0"/>
+      <geometry>
+        <sphere radius="0.02"/>
+      </geometry>
+    </collision>
+    <inertial>
+      <mass value="0.06"/>
+      <inertia ixx="9.6e-06" ixy="0.0" ixz="0.0" iyy="9.6e-06" iyz="0.0" izz="9.6e-06"/>
+    </inertial>
+  </link>
+</robot>
+