Problem on using URDF

Typically: "How do I... ", "How can I... " questions
Post Reply
ahmedelwaly
Posts: 3
Joined: 06 Apr 2021, 21:31

Problem on using URDF

Post by ahmedelwaly »

I am trying to import my robot model using URDF plugin, but when i import, it says

Code: Select all

simExtURDF: info: import operation started.
simExtURDF: info: there are 12 joints.
simExtURDF: error: there is no joint with name ''
simExtURDF: error: there is no joint with name ''
simExtURDF: error: there is no joint with name ''
simExtURDF: error: there is no joint with name ''
simExtURDF: info: there are 13 links.
I don't understand the error "ERROR: there is no joint with name ''" .

Do you have any suggestions as to how to import the model correctly?

coppelia
Site Admin
Posts: 10336
Joined: 14 Dec 2012, 00:25

Re: Problem on using URDF

Post by coppelia »

Hello,

the error means that the joint does not have any name, in the URDF file. This does not always mean that the file is faulty. But what a simulator expects from a file and what is actually in the file can greatly vary.

Does the import operation produce anything? Or what is the problem, next to the error messages?

Cheers

fai
Posts: 10
Joined: 23 Sep 2015, 21:04

Re: Problem on using URDF

Post by fai »

Hi,
I have the same error message, but the imported model seems right.
My urdf file looks like:

<joint name="Rigid13" type="fixed">
<origin rpy="0 0 0" xyz="0.054297 -0.07 0.1"/>
<parent link="base_link"/>
<child link="Quader1_1"/>
</joint>

<joint name="Rev14" type="continuous">
<origin rpy="0 0 0" xyz="0.217851 0.050972 0.1"/>
<parent link="Quader1_1"/>
<child link="Component4_1"/>
<axis xyz="1.0 0.0 0.0"/>

So, it looks like the name for the joints are well defined. In fact, the imported joints in CoppeliaSim appear with these names. So, is this just a bug in the plugging or should the joints be defined in some other way?
Cheers,
Andres

coppelia
Site Admin
Posts: 10336
Joined: 14 Dec 2012, 00:25

Re: Problem on using URDF

Post by coppelia »

Hello Andres,

can you post a minimalistic, self-contained URDF file that illustrates this problem?

Cheers

fai
Posts: 10
Joined: 23 Sep 2015, 21:04

Re: Problem on using URDF

Post by fai »

Sure! Here you go.

Code: Select all

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

<link name="base_link">
  <inertial>
    <origin rpy="0 0 0" xyz="-0.025 0.025 0.1"/>
    <mass value="3.925"/>
    <inertia ixx="0.013901" ixy="-0.0" ixz="-0.0" iyy="0.013901" iyz="0.0" izz="0.001635"/>
  </inertial>
  <visual>
    <origin rpy="0 0 0" xyz="0 0 0"/>
    <geometry>
      <cylinder length="0.6" radius="0.2"/>
    </geometry>
    <material name="silver_default"/>
  </visual>
  <collision>
    <origin rpy="0 0 0" xyz="0 0 0"/>
    <geometry>
      <cylinder length="0.6" radius="0.2"/>
    </geometry>
  </collision>
</link>

<link name="box_v2_1">
  <inertial>
    <origin rpy="0 0 0" xyz="0.025 0.024999999999999994 -0.025"/>
    <mass value="0.98125"/>
    <inertia ixx="0.000409" ixy="0.0" ixz="-0.0" iyy="0.000409" iyz="0.0" izz="0.000409"/>
  </inertial>
  <visual>
    <origin rpy="0 0 0" xyz="-0.0 -0.05 -0.0"/>
    <geometry>
      <box size="0.6 0.1 0.2"/>
    </geometry>
    <material name="silver_default"/>
  </visual>
  <collision>
    <origin rpy="0 0 0" xyz="-0.0 -0.05 -0.0"/>
    <geometry>
      <box size="0.6 0.1 0.2"/>
    </geometry>
  </collision>
</link>

<joint name="Rev2" type="continuous">
  <origin rpy="0 0 0" xyz="0.0 0.05 0.0"/>
  <parent link="base_link"/>
  <child link="box_v2_1"/>
  <axis xyz="0.0 1.0 0.0"/>
</joint>

</robot>

And this is the output:
simExtURDF: info: import operation started.
simExtURDF: info: there are 1 joints.
simExtURDF: error: there is no joint with name ''
simExtURDF: info: there are 2 links.
simExtURDF: info: creating link 'base_link'...
simExtURDF: error: there is no joint with name ''
simExtURDF: info: creating link 'box_v2_1'...
simExtURDF: info: there are 0 sensors.
simExtURDF: info: import operation finished.

The loaded model looks fine: two bodies joined with a revolute joint..

coppelia
Site Admin
Posts: 10336
Joined: 14 Dec 2012, 00:25

Re: Problem on using URDF

Post by coppelia »

Thanks for the file.

Those error messages are actually faulty, and shouldn't show. This is fixed for next release or revision. In the mean time simply ignore them.

Cheers

Post Reply