I had a problem when switching from URDF to XACRO.

asked 2020-03-30 17:04:29 -0600

Ace_Eca
3 ●1 ●3 ●4

updated 2020-03-31 10:48:08 -0600

Hello everyone!!!

I had a problem when switching from URDF to XACRO. I did a urdf check:$ check_urdf pan_tilt_generated.urdf, before generating this: $ pan_tilt_generated.urdf using this command: $ rosrun xacro xacro pan_tilt.xacro --inorder> pan_tilt_generated.urdf.

I can’t find a solution yet. any ideas?

Here such an error is issued by verification:

 ace@ace:~/catkin_ws/src/mastering_ros_robot_description_pkg/urdf$ check_urdf pan_tilt_generated.urdf 
  Error:   radius [] is not a valid float at line 187 in /build/urdfdom-UJ3kd6/urdfdom-0.4.1/urdf_parser/src/link.cpp
    Error:   Could not parse visual element for Link [base_link]  at line 452 in /build/urdfdom-UJ3kd6/urdfdom-0.4.1/urdf_parse/src/link.cpp
    robot name is: pan_tilt
   ---------- Successfully Parsed XML ---------------
  root Link: base_link has 1 child(ren)
     child(1):  pan_link
        child(1):  tilt_link

These errors get the launch of the launch file:

   [ERROR] [1585602978.236429024]: radius [] is not a valid float]
  [ERROR] [1585602978.237213943]: Could not parse visual element for Link [base_link]

but RVIZ, it works and shows the model without errors

this is my code :

<?xml version="1.0"?>
<robot xmlns:xacro="http://www.ros.org/wiki/xacro" name="pan_tilt">
  <xacro:property name="base_link_length" value="1" />
  <xacro:property name="base_link_radius" value="2" />

 <xacro:property name="pan_link_length" value="2" />
 <xacro:property name="pan_link_radius" value="1"/>

 <xacro:property name="tilt_link_length" value="2"/>
 <xacro:property name="tilt_link_radius" value="1"/>


 <xacro:macro name="inertial_matrix" params="mass">
      <inertial>
     <mass value="${mass}" />
     <inertia ixx="0.5" ixy="0.0" ixz="0.0"
          iyy="0.5" iyz="0.0"
          izz="0.5" />
  </inertial>
  </xacro:macro>

  <link name="base_link">
  <visual>
    <geometry>
  <cylinder length="${base_link_length}" radius="${base_link_radius}"/>
    </geometry>
    <origin rpy="0 0 0" xyz="0 0 0"/>
    <material name="yellow">
  <color rgba="1 1 0 1"/>
    </material>
  </visual>
  <collision>
    <geometry>
  <cylinder length="${base_link_length+0.02}" radius="2"/>
    </geometry>
    <origin rpy="0 0 0" xyz="0 0 0"/>
  </collision>
 <xacro:inertial_matrix mass="1"/>
 </link>
 <joint name="pan_joint" type="revolute">
   <parent link="base_link"/>
   <child link="pan_link"/>
   <origin xyz="0 0 0.1"/>
   <axis xyz="0 0 1"/>
   <limit effort="300" velocity="0.1" lower="-3.14" upper="3.14"/>
   <dynamics damping="50" friction="1"/>
</joint>
<link name="pan_link">
  <visual>
    <geometry>
  <cylinder length="${pan_link_length}" radius="${pan_link_radius}"/>
    </geometry>
    <origin rpy="0 0 0" xyz="0 0 0.09"/>
    <material name="red">
      <color rgba="0 0 1 1"/>
    </material>
  </visual>
  <collision>
    <geometry>
  <cylinder length="${pan_link_length}" radius="${pan_link_radius+2}"/>
    </geometry>
    <origin rpy="0 0 0" xyz="0 0 0.09"/>
 </collision>
    <xacro:inertial_matrix mass="1"/>
</link>
<joint name="tilt_joint" type="revolute">
  <parent link="pan_link"/>
  <child link="tilt_link"/>
  <origin xyz="0 0 0.2"/>
  <axis xyz="0 1 0"/>
  <limit effort="300" velocity=".1" lower="-4.64" upper="-1.5"/>
  <dynamics damping="50" friction="1"/>
</joint> ...

(more)

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1

answered 2020-03-31 10:55:04 -0600

David Lu

10932 ●123 ●219 ●250 http://MetroRobots.com/

It works fine on my machine, so I'm guessing the problem is your launch file. Make sure you are running xacro in your launch file. See also: http://wiki.ros.org/urdf/Tutorials/Us...

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Comments

Hello, my launch.

<launch>
<arg name="model"/>
<param name="robot_description" command="$(find xacro)/xacro.py $(find  astering_ros_robot_description_pkg)/urdf/pan_tilt.xacro" />

<param name="use_gui" value="true"/>

<node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher" />
<node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" />
<node name="rviz" pkg="rviz" type="rviz" args="-d $(find mastering_ros_robot_description_pkg)/config/urdf.rviz"  required="true" />
</launch>

Ace_Eca ( 2020-03-31 11:08:57 -0600 )edit

I can not find an explanation for this error, my code starts and works.

 [ ERROR] [1585602978.236429024]: radius [] is not a valid float]
  [ERROR] [1585602978.237213943]: Could not parse visual element for Link [base_link]

Ace_Eca ( 2020-03-31 11:11:22 -0600 )edit

I still cannot replicate your error. What version of ROS are you using?