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Minimal.Launch Failing to build tree: parent link [base_link] of joint [camera_rgb_joint] not found

asked 2016-05-05 13:35:18 -0500

mbisson gravatar image

updated 2016-07-22 15:41:34 -0500

130s gravatar image

Hi ROS Community,

Background: I'm trying to build my own Turtlebot using a Create2 base along with a Jetson TK1 and Kinect Model 1414. I've installed the Indigo ROS-Base package and am using the freenect stack with the Kinect. As far as other package installations are concerned, I followed most of the instructions laid out by YouTuber JetsonHacks who is constructing a similar build but using the Asus Xtion Pro which unfortunately is out of commission. As far as my environment and workspace is concerned I'm confident I have everything set up.

Problem: My issue occurs when I try running the base launch file for Turtlebot (minimal.launch). I have TURTLEBOT_3D_Sensor=kinect and TURTLEBOT_STACKS=circles set in my bashrc. When running roslaunch turtlebot_bringup minimal.launch many processes run clean, but then I get an error message in the console that says the following:

"Failed to build tree: parent link [base_link] of joint [camera_rgb_joint] not found.  This is not valid according to the URDF spec. Every link you refer to from a joint needs to be explicitly defined in the robot description. To fix this problem you can either remove this joint [camera_rgb_joint] from your urdf file, or add "<link name="base_link" />" to your urdf file."

When I try to see the robot model in rviz, under robot model it says "URDF failed Model parse"

I've been able to track down where the file that is causing problems resides, but don't know how to go about solving it. I tried tweaking the file as the error output says to do so, but removing the camera_rgb_joint just led to another parent/child issue. The file in question is: turtlebot_description/urdf/sensors/kinect.urdf.xacro. Did some more testing and after changing my TURTLEBOT_3D_Sensor to asus_xtion_pro, sourcing bashrc and running minimal.launch, the issue described above does not occur and all processes run cleanly. Looking at the asus_xtion_pro.urdf.xacro file, it also contains the same exact lines that were causing the error when using the kinect as the 3D sensor:

  <!-- Parameterised in part by the values in turtlebot_properties.urdf.xacro -->
  <xacro:macro name="sensor_asus_xtion_pro" params="parent">
    <joint name="camera_rgb_joint" type="fixed">
      <origin xyz="${cam_px} ${asus_xtion_pro_cam_py} ${cam_pz}"
              rpy="${cam_or} ${cam_op} ${cam_oy}"/>
      <parent link="${parent}"/>
      <child link="camera_rgb_frame" />

I would attach some pictures, but looks like I need at least 5 karma to do so. Any help would be greatly appreciated. Thanks

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answered 2016-05-05 16:50:17 -0500

mbisson gravatar image

Issue resolved by changing tag in turtlebot/turtlebot_description/robots/create2_circles_kinect.urdf.xacro from "<create2/> to "<create/>".

create2_circles_asus_xtion_pro.urdf.xacro file in the same directory had <create/> tag and since I could successfully see the model in rviz, I figured I'd apply the same change to the create2_circles_kinect.urdf.xacro. Not exactly sure about the underlying reason why it wouldn't work with <create2/> tag though.

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Official turtlebot_descriptionfolder as of today doesn't seem to contain models for create2. Unless you share the code you use it's hard for anyone to tell what was the cause.

130s gravatar image 130s  ( 2016-07-22 15:46:59 -0500 )edit

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Asked: 2016-05-05 13:35:18 -0500

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Last updated: Jul 22 '16