I dont understand the CONTACT SENSOR data.

edit

Hi I am doing the gazebo tutorial called: "Sensors Contact Sensors: How to create and get data from contact sensors."

Then I followed the instructions, where I have a box with the contact sensor TAG:

<sensor name='my_contact' type='contact'>
          <contact>
            <collision>box_collision</collision>
          </contact>
        </sensor>

This box is over the ground plane.

ANd i can see the sensor information with the instruction: gztopic echo /gazebo/default/box/link/my_contact

BUt i dont understand what does it mean.

-what does this information mean?

contact {
  collision1: "box::link::box_collision"
  collision2: "ground_plane::link::collision"

position {
    x: -0.500000000462553
    y: 0.49999999823938179
    z: -1.3116396857526524e-11
  }
  position {
    x: 0.499999999537447
    y: 0.49999999830396458
    z: -1.3116396855009743e-11
  }
  normal {
    x: 0
    y: 0
    z: 1
  }
  normal {
    x: 0
    y: 0
    z: 1
  }
  depth: 1.3116396857526524e-11
  depth: 1.3116396855009743e-11
  wrench {
    body_1_name: "box::link::box_collision"
    body_2_name: "ground_plane::link::collision"
    body_1_force {
      x: 0.18159452738357906
      y: -0.58800230161463551
      z: 2.9400153496814356
    }
    body_2_force {
      x: 0
      y: 0
      z: 0
    }
    body_1_torque {
      x: 1.1760044494554212
      y: 1.3792103044659421
      z: 0.2032039939184285
    }
    body_2_torque {
      x: 0
      y: 0
      z: 0
    }
  }
  wrench {
    body_1_name: "box::link::box_collision"
    body_2_name: "ground_plane::link::collision"
    body_1_force {
      x: -0.18159452730762679
      y: -0.5880023016380882
      z: 2.9400153496814232
    }
    body_2_force {
      x: 0
      y: 0
      z: 0
    }
    body_1_torque {
      x: 1.1760044496335631
      y: -1.3792103043140376
      z: -0.20320399391842819
    }
    body_2_torque {
      x: 0
      y: 0
      z: 0
    }
  }
  time {
    sec: 29
    nsec: 599000000
  }
}

...