scene_manager

Scene Manager package is a ROS package created by Robotnik to help build and interact with MoveIt’s robot’s planning scene.

Background Info

MoveIt Planning Scene

• Is an object used for storing the representation of the world around the robot (external collisions) and also the state of the robot itself (internal collisions and current position).
• The collision environment can be built using MoveIt Collision Objects or Octomap.
• The Planning Scene is used by MoveIt during path planning, to obtain collision-free trajectories.
• It is important to have an accurate representation of the world.
• MoveIt allows the user to interact with Collision Objects (attach, detach objects) present in the Planning Scene.

Scene Manager

• Facilitates the creation of the Planning Scene, as well as the interaction with the Planning Scene.
• C++ Class that inherits from the Class moveit::planning_interface::PlanningSceneInterface.
• API that allows user to easily interact with the MoveIt Planning Scene.

Advantages

• MoveIt Collision Objects are easily defined in a YAML file that can be modified at any time.
• Allows user to construct matrices of same object (useful for palletizing applications).
• Adds new functionalities to interact with objects (ex: move relative to object, enable/disable collision checking with object, ..).
• Exposes ROS Services to call all Scene Manager functionalities, external user can easily interact with the environment.
• Includes visualization in RViz of object names.
• Publishes object's frame with respect to world in TF Tree.

How to add Scene Manager to a project

• Add scene_manager and scene_manager_msgs packages to catkin workspace.

• Inside the ROS package where you are going to use the Scene Manager add the depency to the above packages both in CMakeLists.txt and package.xml files.

• Add Scene Manager library to the CPP node you are developing:

  #include <corosect_manipulation/scene_manager.h>
  

• Create object of SceneManager Class:

  ros::NodeHandle nh;
  // Init Scene Manager
  bool wait = true;
  std::unique_ptr<SceneManager> scene_manager_ = std::make_unique<SceneManager>(nh , wait);
  

Scene Manager YAML:

Allows user to easily add Collision Objects into a Planning Scene, for each object one should add the following attributes:

• spawn: By default the object is added to Planning Scene during initialization of scene by Scene Manager.

• static: Static objects cannot be manipulated, nor its position in space changed.

• frame_id: Object's position in scene is defined with respect to this axes.

• geometry: Geometric shape (box) or route to mesh file (package://ros_package_name/route_to_file_folder/mesh_file_name.stl).

• pose: xyz displacement or rpy orientation with respect to the frame_id axes.

• layout: Can be used to add a matrix of the current object (ex: pallet with boxes).

  

Scene Manager Functionalities:

Scene Manager class exposes the following methods:

• SceneManager::initScene() : Adds objects defined in YAML file to the Planning Scene.
• SceneManager::addObjects(vector< string > object_ids) : Add specific object to Planning Scene.
• SceneManager::removeObjects(vector< string > object_ids) : Remove specific object to Planning Scene.
• SceneManager::attachObjects(vector< string > object_ids) : Attach collision object to end-effector.
• SceneManager::detachObjects(vector< string > object_ids) : Detach collision object to end-effector.
• SceneManager::moveRelativeTo(string object_id, rel_pose) : Move end-effector with a relative pose with respect to a given object's frame id.
• SceneManager::allowCollision(string link_id, vector< string > objects_id) : Allows collision between a robot link or a collision object with respect to other collision object.
• SceneManager::restoreCollision(string link_id, vector< string > objects_id) : Restores collision avoidance between a robot link or a collision object with respect to other collision object.

Scene Manager ROS Services:

Scene Manager exposes ROS Services to call all Scene Manager functionalities, external user can easily interact with the arm and the scene.

• /scene_manager/add_objects
• /scene_manager/remove_objects
• /scene_manager/attach_objects
• /scene_manager/detach_objects
• /scene_manager/modify_object
• /scene_manager/move_relative_to