Hi everyone,

I am trying to get the gazebo_ros_bumper plugin to work.

All information I can see are the rising time steps, when I am listening to the topic via rostopic. The states array stays empty.

I used a predifined robot from the gazebo database as an obstacle to avoid colliding with a model in "resting state" like in the attached picture. But this doesn't seem to work either.

This is how I implement the plugin in my SDF model.

<link name="bumper_base">
    <pose>-0.075 0 0.05   0 0 0</pose>
    <inertial>
        <mass>0.01</mass>
    </inertial>
    <collision name="bumper_base_collision">
        <pose>0.0 0 0   0 0 0</pose>
        <geometry>
            <cylinder>
                <radius>0.33</radius>
                <length>0.03</length>
            </cylinder>
        </geometry>
    </collision>
    <visual name="bumper_base_visual">
        <pose>0 0 0   0 0 0</pose>
        <geometry>
            <cylinder>
                <radius>0.33</radius>
                <length>0.03</length>
            </cylinder>
        </geometry>
        <material>
            <ambient>0.83 0.55 0.09 1</ambient>         
        </material> 
    </visual>

   <collision name="bumper_tail_collision">
        <pose>-0.30 0 0   0 0 0</pose>
        <geometry>
            <cylinder>
                <radius>0.18</radius>
                <length>0.03</length>
            </cylinder>
        </geometry>
    </collision>
    <visual name="bumper_tail_visual">
        <pose>-0.30 0 0   0 0 0</pose> 
        <geometry>
            <cylinder>
                <radius>0.18</radius>
                <length>0.03</length>
            </cylinder>
        </geometry>
        <material>
            <ambient>0.83 0.55 0.09 1</ambient>
        </material>
    </visual>


    <sensor name="bumper_front" type="contact">
        <always_on>true</always_on>
        <update_rate>10</update_rate>
        <visualize>true</visualize>
        <pose>0 0 0   0 0 0</pose>
        <topic>bumper_base</topic>
        <contact>
            <collision>bumper_base_collision></collision>
            <topic>bumper_base</topic>
        </contact>

        <plugin name="gazebo_ros_laser" filename="/home/christoph/catkin_workspace_groovy/devel/lib/libgazebo_ros_bumper.so">
            <bumperTopicName>bumper_base</bumperTopicName> 
            <frameName>bumper_base</frameName>
        </plugin> 
    </sensor>
</link>



<!-- Bumper Joint -->
<joint name="bumper_front_joint" type="revolute">
    <pose>0  0  0  0  0  0</pose>
    <parent>base_link</parent>
    <child>bumper_base</child>
    <axis>
        <xyz>1 0 0</xyz>
        <limit>
            <upper>0</upper>
            <lower>0</lower>
        </limit>
    </axis>
</joint>

My plan is to check the size of the state array from the contact message to see if there are any collisions.

Is it correct, that the callback function will recieve messages in the given update_rate even if there aren't any collisions? And is this necessary or is it possible to only get messages when a collision is detected?

Update 1:

I tried to get a collision reaction by building a collision obstacle like in this tutorial: link

But that didn't change anything.

Thanks in advance, Christoph