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

  <link name="shoulder_link">
    <visual>
      <geometry><box size="0.1 0.1 0.1"/></geometry>
      <material name="blue"><color rgba="0 0 1 1"/></material>
    </visual>
  </link>

  <link name="upper_arm_link">
    <visual>
      <geometry><cylinder radius="0.03" length="0.3"/></geometry>
      <material name="red"><color rgba="1 0 0 1"/></material>
    </visual>
  </link>

  <joint name="shoulder_joint" type="revolute">
    <parent link="shoulder_link"/>
    <child link="upper_arm_link"/>
    <origin xyz="0 0 -0.05" rpy="0 0 0"/>
    <axis xyz="0 1 0"/>
    <limit lower="-1.57" upper="1.57" effort="10" velocity="1"/>
  </joint>

</robot>