johannesm's profile - activity

The table launch files runs the spawn_model node. Unfortunately, if I use: "<link name="world" />" as my urdf's root node this makes the spawn_model node ignore all the position parameters i give it. The model will always be aligned to 0,0,0 then.

Thanks for this idea. I have now written it as a xacro file. I include the needed height variables using environment variables. It is not very clean but it works.

Run in bash before: "export TEST_POS_X=4" In urdf.xacro included: "$(optenv TEST_POS_X 0)". Zero is default

Hi,

I want to create a simple urdf object consisting of a:

• Box_A, which is fixed in the world. No matter what external forces apply on it, it should stay in the same place. (fixed)
• Box_B, which is connect to Box_A with a revolute joint. (dynamic)

In " http://answers.ros.org/question/29437/possible-to-declare-static-object-in-urdf-file/ " a way to this was figured out using a world link:

<robot name="Test" xmlns:controller="..." xmlns:interface="..." xmlns:sensor="...">
<link name="world" />
<link name="Box_A">
 ... definition of the box
</link>
<link name="Box_B">
 ... definition of the box
</link>

<joint name="world_joint" type="fixed">
    <!-- Here I have to define the global position of Box_A -->
    <origin rpy="0 0 0" xyz="0 0 1"/>
    <parent link="world"/>
    <child link="Box_A"/>
</joint>
<joint name="boxa_to_boxb_joint" type="revolute">
    <axis xyz="1 0 0"/>
    <origin rpy="0 0 0" xyz="-0.15 0.1 0.00"/>
    <limit effort="0.01" lower="-3.14159265359" upper="1.57079632679" velocity="0.001"/>
    <parent link="Box_A"/>
    <child link="Box_B"/>
    <dynamics damping="1.0" friction="1.0"/>
    <safety_controller k_velocity="0.1"/>
</joint>
</robot>

This code works fine, resulting in a swinging Box connected to a fixed Box. However, this solution blocks the possibility to spawn the object at a certain position at runtime.

Can you think of other solutions which still use the spawn_urdf_model service's parameters (position, orientation)? For example, something like to use a static modifier on Box_A?

<gazebo reference="Box_A">
  <static>true</static>
</gazebo>

But that does unfortunately not work for me.

Thank you in advance, Johannes

Hi,

I'm currently doing some simple (abstract) simulations within ros_gazebo (ROS electric).

I'm now at a point where I would have to use controllers for my joints exceedingly, but then I just found Gazebo's animate_joint plugin (http://gazebosim.org/wiki/tutorials/intermediate/animate_joint). Its ability do define animation using keyframes and not using forces seems like a simple solution for my problems.

Has anyone experience using this plugin with ros_gazebo electric?

Thank you, Johannes