Not sure how to work with the contact sensor. [closed]

edit

Hello, New to gazebo.

I am trying to add a sensor to a link and get force values. I am using a urdf. I tried the tutorial for the force torque sensor on gazebo but it didn't work. I tried the contact sensor. IT shows up in the rostopic list. However, does not show any information.

On further investigation, the issue seems to be the collision name within the sensor tag. Most resources say that when gazebo converts the file from a *.urdf.xacro to a *.sdf it messes with the names. Is there a way to see these changes?

I tried converting the file to a sdf but it did not work as expected.

The gazebo code is here:

<gazebo reference="${name}_finger_33_sensor">
        <material>Gazebo/Black</material>
        <sensor type="contact" name="contact_sensor">
                    <always_on>true</always_on>
                    <update_rate>1.0</update_rate>
                                    <contact>
                    <collision>${name}_finger_13_sensor_collision</collision>
                    </contact>
                        <plugin name="contact_plugin" filename="libgazebo_ros_bumper.so"> 
                        <alwaysOn>true</alwaysOn>
                        <updateRate>8</updateRate>
                        <bumperTopicName>contact_sensor</bumperTopicName>
                    <frameName>${name}_finger_33_sensor</frameName>
                        </plugin>
                    </sensor>
            </gazebo>

I can see contact_sensor when I enter rostopic list in the terminal.This is what I get when i use rostopic echo

Thanks for the help in advance. If you also know how to import the data to use it in python kindly let me know.