Non-mesh version of tutorial URDF: https://raw.githubusercontent.com/ros/urdf_tutorial/master/urdf/07-physics.urdf

simple_robot.urdf

<?xml version="1.0"?>
<robot name="physics">
  <link name="base_link">
    <visual>
      <geometry>
        <cylinder length="0.6" radius="0.2"/>
      </geometry>
      <material name="blue">
        <color rgba="0 0 .8 1"/>
      </material>
    </visual>
    <collision>
      <geometry>
        <cylinder length="0.6" radius="0.2"/>
      </geometry>
    </collision>
    <inertial>
      <mass value="10"/>
      <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
    </inertial>
  </link>

  <link name="right_leg">
    <visual>
      <geometry>
        <box size="0.6 .2 .1"/>
      </geometry>
      <origin rpy="0 1.57075 0" xyz="0 0 -0.3"/>
      <material name="white">
        <color rgba="1 1 1 1"/>
      </material>
    </visual>
    <collision>
      <geometry>
        <box size="0.6 .2 .1"/>
      </geometry>
      <origin rpy="0 1.57075 0" xyz="0 0 -0.3"/>
    </collision>
    <inertial>
      <mass value="10"/>
      <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
    </inertial>
  </link>

  <joint name="base_to_right_leg" type="fixed">
    <parent link="base_link"/>
    <child link="right_leg"/>
    <origin xyz="0.22 0 .25" rpy="0.0 0.0 0.0"/>
  </joint>

  <link name="right_base">
    <visual>
      <geometry>
        <box size=".1 0.4 .1"/>
      </geometry>
      <material name="white"/>
    </visual>
    <collision>
      <geometry>
        <box size=".1 0.4 .1"/>
      </geometry>
    </collision>
    <inertial>
      <mass value="10"/>
      <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
    </inertial>
  </link>

  <joint name="right_base_joint" type="fixed">
    <parent link="right_leg"/>
    <child link="right_base"/>
    <origin xyz="0 0 -0.6" rpy="0.0 0.0 0.0"/>
  </joint>

  <link name="right_front_wheel">
    <visual>
      <geometry>
        <cylinder length=".1" radius="0.035"/>
      </geometry>
      <material name="black">
        <color rgba="0 0 0 1"/>
      </material>
    </visual>
    <collision>
      <geometry>
        <cylinder length=".1" radius="0.035"/>
      </geometry>
    </collision>
    <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="right_front_wheel_joint" type="continuous">
    <axis xyz="0 0 1"/>
    <parent link="right_base"/>
    <child link="right_front_wheel"/>
    <origin rpy="0 1.57075 0" xyz="0 0.133333333333 -0.085"/>
    <limit effort="100" velocity="100"/>
    <joint_properties damping="0.0" friction="0.0"/>
  </joint>

  <link name="right_back_wheel">
    <visual>
      <geometry>
        <cylinder length=".1" radius="0.035"/>
      </geometry>
      <material name="black"/>
    </visual>
    <collision>
      <geometry>
        <cylinder length=".1" radius="0.035"/>
      </geometry>
    </collision>
    <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="right_back_wheel_joint" type="continuous">
    <axis xyz="0 0 1"/>
    <parent link="right_base"/>
    <child link="right_back_wheel"/>
    <origin rpy="0 1.57075 0" xyz="0 -0.133333333333 -0.085"/>
    <limit effort="100" velocity="100"/>
    <joint_properties damping="0.0" friction="0.0"/>
  </joint>

  <link name="left_leg">
    <visual>
      <geometry>
        <box size="0.6 .2 .1"/>
      </geometry>
      <origin rpy="0 1.57075 0" xyz="0 0 -0.3"/>
      <material name="white"/>
    </visual>
    <collision>
      <geometry>
        <box size="0.6 .2 .1"/>
      </geometry>
      <origin rpy="0 1.57075 0" xyz="0 0 -0.3"/>
    </collision>
    <inertial>
      <mass value="10"/>
      <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
    </inertial>
  </link>

  <joint name="base_to_left_leg" type="fixed">
    <parent link="base_link"/>
    <child link="left_leg"/>
    <origin xyz="-0.22 0 .25" rpy="0.0 0.0 0.0"/>
  </joint>

  <link name="left_base">
    <visual>
      <geometry>
        <box size=".1 0.4 .1"/>
      </geometry>
      <material name="white"/>
    </visual>
    <collision>
      <geometry>
        <box size=".1 0.4 .1"/>
      </geometry>
    </collision>
    <inertial>
      <mass value="10"/>
      <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
    </inertial>
  </link>

  <joint name="left_base_joint" type="fixed">
    <parent link="left_leg"/>
    <child link="left_base"/>
    <origin xyz="0 0 -0.6" rpy="0.0 0.0 0.0"/>
  </joint>

  <link name="left_front_wheel">
    <visual>
      <geometry>
        <cylinder length=".1" radius="0.035"/>
      </geometry>
      <material name="black"/>
    </visual>
    <collision>
      <geometry>
        <cylinder length=".1" radius="0.035"/>
      </geometry>
    </collision>
    <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="left_front_wheel_joint" type="continuous">
    <axis xyz="0 0 1"/>
    <parent link="left_base"/>
    <child link="left_front_wheel"/>
    <origin rpy="0 1.57075 0" xyz="0 0.133333333333 -0.085"/>
    <limit effort="100" velocity="100"/>
    <joint_properties damping="0.0" friction="0.0"/>
  </joint>

  <link name="left_back_wheel">
    <visual>
      <geometry>
        <cylinder length=".1" radius="0.035"/>
      </geometry>
      <material name="black"/>
    </visual>
    <collision>
      <geometry>
        <cylinder length=".1" radius="0.035"/>
      </geometry>
    </collision>
    <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="left_back_wheel_joint" type="continuous">
    <axis xyz="0 0 1"/>
    <parent link="left_base"/>
    <child link="left_back_wheel"/>
    <origin rpy="0 1.57075 0" xyz="0 -0.133333333333 -0.085"/>
    <limit effort="100" velocity="100"/>
    <joint_properties damping="0.0" friction="0.0"/>
  </joint>
  <joint name="gripper_extension" type="prismatic">
    <parent link="base_link"/>
    <child link="gripper_pole"/>
    <limit effort="1000.0" lower="-0.38" upper="0" velocity="0.5"/>
    <origin rpy="0 0 1.57075" xyz="0 0.19 .2"/>
  </joint>

  <link name="gripper_pole">
    <visual>
      <geometry>
        <cylinder length="0.2" radius=".01"/>
      </geometry>
      <origin rpy="0 1.57075 0 " xyz="0.1 0 0"/>
      <material name="Gray">
        <color rgba=".7 .7 .7 1"/>
      </material>
    </visual>
    <collision>
      <geometry>
        <cylinder length="0.2" radius=".01"/>
      </geometry>
      <origin rpy="0 1.57075 0 " xyz="0.1 0 0"/>
    </collision>
    <inertial>
      <mass value="0.05"/>
      <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
    </inertial>
  </link>

  <joint name="left_gripper_joint" type="revolute">
    <axis xyz="0 0 1"/>
    <limit effort="1000.0" lower="0.0" upper="0.548" velocity="0.5"/>
    <origin rpy="0 0 0" xyz="0.2 0.01 0"/>
    <parent link="gripper_pole"/>
    <child link="left_gripper"/>
  </joint>

  <link name="left_gripper">
    <visual>
      <origin rpy="0.0 0 0" xyz="0 0 0"/>
      <geometry>
        <box size=".08 .08 .08"/>
      </geometry>
    </visual>
    <collision>
      <geometry>
        <box size=".08 .08 .08"/>
      </geometry>
      <origin rpy="0.0 0 0" xyz="0 0 0"/>
    </collision>
    <inertial>
      <mass value="0.05"/>
      <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
    </inertial>
  </link>

  <joint name="left_tip_joint" type="fixed">
    <parent link="left_gripper"/>
    <child link="left_tip"/>
  </joint>

  <link name="left_tip">
    <visual>
      <origin rpy="0.0 0 0" xyz="0.09137 0.00495 0"/>
      <geometry>
        <box size=".08 .08 .08"/>
      </geometry>
    </visual>
    <collision>
      <geometry>
        <box size=".08 .08 .08"/>
      </geometry>
      <origin rpy="0.0 0 0" xyz="0.09137 0.00495 0"/>
    </collision>
    <inertial>
      <mass value="0.05"/>
      <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
    </inertial>
  </link>

  <joint name="right_gripper_joint" type="revolute">
    <axis xyz="0 0 -1"/>
    <limit effort="1000.0" lower="0.0" upper="0.548" velocity="0.5"/>
    <origin rpy="0 0 0" xyz="0.2 -0.01 0"/>
    <parent link="gripper_pole"/>
    <child link="right_gripper"/>
  </joint>

  <link name="right_gripper">
    <visual>
      <origin rpy="-3.1415 0 0" xyz="0 0 0"/>
      <geometry>
        <box size=".08 .08 .08"/>
      </geometry>
    </visual>
    <collision>
      <geometry>
        <box size=".08 .08 .08"/>
      </geometry>
      <origin rpy="-3.1415 0 0" xyz="0 0 0"/>
    </collision>
    <inertial>
      <mass value="0.05"/>
      <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
    </inertial>
  </link>

  <joint name="right_tip_joint" type="fixed">
    <parent link="right_gripper"/>
    <child link="right_tip"/>
  </joint>

  <link name="right_tip">
    <visual>
      <origin rpy="-3.1415 0 0" xyz="0.09137 0.00495 0"/>
      <geometry>
        <box size=".08 .08 .08"/>
      </geometry>
    </visual>
    <collision>
      <geometry>
        <box size=".08 .08 .08"/>
      </geometry>
      <origin rpy="-3.1415 0 0" xyz="0.09137 0.00495 0"/>
    </collision>
    <inertial>
      <mass value="0.05"/>
      <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
    </inertial>
  </link>

  <link name="head">
    <visual>
      <geometry>
        <sphere radius="0.2"/>
      </geometry>
      <material name="white"/>
    </visual>
    <collision>
      <geometry>
        <sphere radius="0.2"/>
      </geometry>
    </collision>
    <inertial>
      <mass value="10"/>
      <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
    </inertial>
  </link>

  <joint name="head_swivel" type="revolute">
    <parent link="base_link"/>
    <child link="head"/>
    <axis xyz="0 0 1"/>
    <origin xyz="0 0 0.3" rpy="0.0 0.0 0.0"/>
  </joint>

  <link name="box">
    <visual>
      <geometry>
        <box size=".08 .08 .08"/>
      </geometry>
      <material name="blue"/>
    </visual>
    <collision>
      <geometry>
        <box size=".08 .08 .08"/>
      </geometry>
    </collision>
    <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="tobox" type="fixed">
    <parent link="head"/>
    <child link="box"/>
    <origin xyz="0 0.1414 0.1414" rpy="0.0 0.0 0.0"/>
  </joint>

</robot>