Bumper

The bumper plugins publishes the state of Collisions of bodies in the model. The Collision and Collisions message are defined in flatland_msgs. It publishes empty collisions if there are nothing colliding. Note that the force values published by the bumper is a ball park approximation of impact strength.

The definition of Collisions and Collision messages are shown below.

string entity_A              # the name of this model
string body_A                # this model's body
string entity_B              # name of the other entity, model or layer, collided with this model
string body_B                # body of the other entity
float64[] magnitude_forces   # force of impact at each point
Vector2[] contact_positions  # list of contact points
Vector2[] contact_normals    # list of contact normals, normals always go from body_A to body_B

std_msgs/Header header
Collision[] collisions  # list of Collision message

Vector2 is defined in flatland_msgs

float64 x
float64 y

The descriptions of parameters are shown below.

plugins:

    # required, specify Bumper type to load the plugin
  - type: Bumper

    # required, name of the plugin, unique within the model
    name: MyBumper

    # optional, default to "map", the frame_id of the world coordinate system,
    # Collision contain collision points that must have a reference frame
    world_frame_id: world

    # optional, default to "collisions", the topic name to publish collision
    # messages, you begin with "/" to ignore model namespace
    topic: collisions

    # optional, default to inf (publishes every time step), the rate in Hz to
    # publish the Collisions messages
    update_rate: .inf

    # optional, default to true, this works together with update_rate. Collision
    # states may change in between updates with a given update_rate. It might
    # appear and disappear between when the messages published. This option
    # forces the bumper plugin to always publish if there are non-zero number
    # collisions regardless of update_rate. If there are no collisions, it publishes
    # empty list of collisions at update_rate
    publish_all_collisions: true

    # optional, default to [], the list of bodies to ignore, ignored bodies
    # will not have their collision state published
    exclude: []

  # another example
  - type: Bumper
    name: MyOtherBumper
    publish_all_collisions: false
    update_rate: 60
    exclude: ["left_wheel", "right_wheel"]