Hi All,

I am currently trying to set up a camera in Gazebo, to display the content of the simulation in rviz. However, I cannot see anything in the camera image.

To do that, I use the universal robot package on ROS Kinetic, and modify the ur5_robot.urdf.xacro file. I simply added the camera links and joints + the gazebo tags, as presented in the Gazebo tutorial on cameras.

Here is the modified ur5_robot.urdf.xacro file that I use:

<?xml version="1.0"?>
<robot xmlns:xacro="http://wiki.ros.org/xacro" name="ur5">

  <!-- Add a camera in the URDF -->
  <xacro:property name="camera_yaw_angle" value="${pi/2}" />  
  <xacro:property name="camera_roll_angle" value="${-pi/2 - pi/6}" />  
  <xacro:property name="camera_depth" value="0.05" />
  <xacro:property name="camera_height" value="0.07" />
  <xacro:property name="camera_length" value="0.15" />
  <xacro:property name="camera_z_offset" value="0.01" />
  <!-- Size of square 'camera' box -->
  <xacro:property name="camera_x" value="2" />
  <!-- x position of 'camera' box -->
  <xacro:property name="camera_y" value="0.05" />
  <!-- y position of 'camera' box -->
  <xacro:property name="camera_z" value="0.5" />
  <!-- z position of 'camera' box -->

  <joint name="camera_joint" type="fixed">
    <axis xyz="0 1 0" />
    <origin xyz="${camera_x} ${camera_y} ${camera_z}" rpy="${camera_roll_angle} 0 ${camera_yaw_angle}"/>
    <parent link="world"/>
    <child link="camera_link"/>
  </joint>

  <!-- Camera -->
  <link name="camera_link">
    <collision>
      <origin xyz="0 0 ${-1 * camera_depth - camera_z_offset}" rpy="0 0 0"/>
      <geometry>
        <box size="${camera_length} ${camera_height} ${camera_depth}"/>
      </geometry>
    </collision>

    <visual>
      <origin xyz="0 0 ${-1 * camera_depth - camera_z_offset}" rpy="0 0 0"/>
      <geometry>
        <box size="${camera_length} ${camera_height} ${camera_depth}"/>
      </geometry>
      <material name="red"/>
    </visual>

    <inertial>
      <mass value="1e-5" />
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <inertia ixx="1e-6" ixy="0" ixz="0" iyy="1e-6" iyz="0" izz="1e-6" />
    </inertial>
  </link>

  <gazebo reference="camera_link">
    <sensor type="camera" name="camera1">
      <update_rate>30.0</update_rate>
      <camera name="head">
        <horizontal_fov>1.3962634</horizontal_fov>
        <image>
          <width>800</width>
          <height>800</height>
          <format>R8G8B8</format>
        </image>
        <clip>
          <near>0.02</near>
          <far>300</far>
        </clip>
        <noise>
          <type>gaussian</type>
          <!-- Noise is sampled independently per pixel on each frame.
               That pixel's noise value is added to each of its color
               channels, which at that point lie in the range [0,1]. -->
          <mean>0.0</mean>
          <stddev>0.007</stddev>
        </noise>
      </camera>

      <plugin name="camera_controller" filename="libgazebo_ros_camera.so">
        <alwaysOn>true</alwaysOn>
        <updateRate>0.0</updateRate>
        <cameraName>ur5/camera1</cameraName>
        <imageTopicName>image_raw</imageTopicName>
        <cameraInfoTopicName>camera_info</cameraInfoTopicName>
        <frameName>camera_link</frameName>
        <hackBaseline>0.07</hackBaseline>
        <distortionK1>0.0</distortionK1>
        <distortionK2>0.0</distortionK2>
        <distortionK3>0.0</distortionK3>
        <distortionT1>0.0</distortionT1>
        <distortionT2>0.0</distortionT2>
      </plugin>
    </sensor>
  </gazebo>

  <xacro:arg name="transmission_hw_interface" default="hardware_interface/PositionJointInterface"/>

  <!-- common stuff -->
  <xacro:include filename="$(find ur_description)/urdf/common.gazebo.xacro" />

  <!-- ur5 -->
  <xacro:include filename="$(find ur_description)/urdf/ur5.urdf.xacro" />

  <!-- arm -->
  <xacro:ur5_robot prefix="" joint_limited="false" transmission_hw_interface="$(arg transmission_hw_interface)" />

  <link name="world" />

  <joint name="world_joint" type="fixed">
    <parent link="world" />
    <child link = "base_link" />
    <origin xyz="0.0 0.0 0.0" rpy="0.0 0.0 0.0" />
  </joint>

</robot>

The new code that I added to the ur5_robot.urdf.xacro file is everything up to

<xacro:arg name="transmission_hw_interface" default="hardware_interface/PositionJointInterface"/>

Everything else is the same.

Then, I launch the gazebo simulation by simply using this command.

roslaunch ur_gazebo ur5.launch

When I run rqt_image view, I see nothing in the camera image.

rosrun rqt_image_view rqt_image_view

When I add a camera into rviz, I see only the robot arm in the scene. If I add a cube or a sphere in gazebo in front of the camera, I cannot see the cube/sphere in rviz from the camera widget. Still only displaying the robot.

Can somebody explain to me what is going on here? I assume I am doing something wrong, but there is almost nothing in the file, so I am confused about why this isn't working.

Thank you!

  <joint name="camera_joint" type="fixed">
    <axis xyz="0 1 0" />
    <origin xyz="${camera_x} ${camera_y} ${camera_z}" rpy="${camera_roll_angle} 0 ${camera_yaw_angle}"/>
    <parent link="world"/>
    <child link="camera_link"/>
  </joint>