CoSTAR

Collaborative System for Task Automation and Recognition

This is a project by a few members of the JHU Laboratory for Computational Sensing and Robotics, namely Chris Paxton, Kel Guerin, Andrew Hundt, and Felix Jonathan. Our goal is to build a system which facilitates end-user instruction of industrial robots to performa a variety of different tasks. CoSTAR allows users to program robots to perform complex tasks such as sorting, assembly, and more.

For more videos you can check out the CoSTAR YouTube Channel.

These are the tools and utilities we created to get the CoSTAR project up and off the ground. This document describes the CoSTAR project for an LBR iiwa 14 R820 with an attahed Robotiq 3-finger adaptive gripper.

To fully take advantage of these capabilities you will need:

• sp_segmenter: object detection and pose estimation library
• instructor: our custom user interface
• a KUKA LBR iiwa
• a Robotiq 3-finger gripper

Note that unfortunately the CoSTAR UI is not open source, so email me at cpaxton3@jhu.edu if you are interested in it.

Starting CoSTAR for the LBR iiwa with GRL

Making sure you are connected to the robot:

ping 192.170.10.2 # connection to FRI port for joint states
ping 172.31.1.146 # connection to Robotiq 3-finger gripper to send commands
ping 172.31.1.147 # connection to JAVA port on the robot to send commands

How to bring this robot up on our own platform:

# core features and UI
roslaunch costar_bringup iiwa14_s_model.launch
roslaunch instructor_core instructor.launch

# object detection and moveit planning scene
roslaunch sp_segmenter SPServerStructureAssembly.launch

You also need to launch the GRL KUKA ROS Driver. GRL is the Generic Robot Library, which provides a low-level control interface for the KUKA LBR.

In particular, costar_bringup will launch the robot command driver, the gripper command services, the MoveIt services, Predicator, and Librarian.

To bring up the tool attachments run:

roslaunch ready_air stomper_tool.launch

Starting CoSTAR in a Simulation

You can test CoSTAR in a simulation now. The basic launch procedure for a simulation is to run these commands:

roslaunch iiwa_gazebo iiwa_gazebo.launch trajectory:=false
roslaunch costar_bringup iiwa14_s_model.launch sim:=true start_sim:=false
roslaunch instructor_core instructor.launch

You can then use the Instructor UI to move the robot around in simulation. If you want to bring up Gazebo and all the drivers at once instead of separately, launch as:

roslaunch costar_bringup iiwa14_s_model.launch sim:=true start_sim:=true
roslaunch instructor_core instructor.launch

Included CoSTAR Components

• Bringup: launch files, RVIZ configurations, et cetera
• Librarian: file management
• Predicator: robot knowledge management
• Gripper: utilities for integrating different grippers into UI
• Robot: utilities and services allowing high-level control of the robot and integrating these behaviors into the UI
• Tools: packages used for data collection, maintaining MoveIt planning scene, and other purposes

Other Requirements

• SP Segmenter

Proprietary Code

• Instructor: Behavior Tree-based user interface (built on Beetree)
• Ready Air: drives the current tool attachment and provides services

Due to licensing issues these cannot be made open source.

CoSTAR Tools

This section includes the code to manage the MoveIt collision detection and a few other utilities that provide useful services for creating powerful robot programs.

MoveIt collision detection: creates a PlanningScene based on detected objects, plus adds a table.

Run with:

roslaunch moveit_collision_environment colision_env.launch mesh_source:=$(find moveit_collision_environment)/data/mesh tableTFname:=ar_marker_2 defineParent:=true parentFrameName:=/world

Recording point clouds: this is used to collect data and scan objects. Run with:

rosrun point_cloud_recorder point_cloud_recorder.py _id:=$OBJECT_NAME _camera:=$CAMERA_ID

This will expose the /record_camera rosservice which can be called from a UI node. Files will be created wherever you ran the point cloud recorder.

Roslaunch would look something like:

<node name="point_cloud_recorder" pkg="point_cloud_recorder" type="point_cloud_recorder.py">
  <param name="id" value="NameOfMyObject"/>
  <param name="camera" value="kinect2"/>
</node>

Gripper

• Simple S Model Server: This is a part of our CoSTAR UI -- cross platform robot graphical user interface for teaching complex behaviors to industrial robots. This wraps a couple simple 3-finger gripper commands, which we can then expose as UI behaviors.=

Librarian

Provide simple interface for managing files used by CoSTAR programs. This is a very simple file system that works well for distributed ROS projects using multiple computers.

• Types: high level categories; use these to group definitions of different items/variables used in a CoSTAR workspace.
• Items: items are represented as files, and can be saved/loaded as ROS parameters.

The librarian_bringup package contains launch files for Librarian. As such, you can launch the librarian core easily with:

roslaunch librarian_bringup core.launch

To change the location of the folder Librarian stores and reads files from, simply change the librarian_root parameter:

roslaunch librarian_bringup core.launch librarian_root:=~/.costar/

Start librarian_core with the directory you want to use for saving/loading files, on the machine which files should be saved on. Librarian is started automatically by the main costar_bringup launch files and is initialized to the ~/.costar directory.

Predicator

Predicator is the CoSTAR package for logical statements.

This software is further described and used in these papers:

    1. Guerin, K., Lea, C., Paxton, C., & Hager, G.D. (2015).
       A Framework for End-User Instruction of a Robot Assistant for Manufacturing.
       In IEEE International Conference on Robotics and Automation (ICRA).
    2. Paxton, C., Bohren, J., & Hager, G. D. (2014).
       Standards for Grounding Symbols for Robotic Task Ontologies.
       At IROS 2014 workshop on Standardized Knowledge Representation and Ontologies for Robotics and Automation.

Starting Predicator

There is a package called predicator_bringup that will start different predicator modules and the predicator core. You can launch the core only with:

roslaunch predicator_bringup core.launch

This will launch the predicator_params module as well if params:=true is set (it is set by default). This is the service which lets other programs manually configure predicator parameters.

You can optionally start different components directly from rosrun. First start predicator_core to listen to predicate statements from modules:

rosrun predicator_core core.py

Once the core is up and running, you can launch different modules to produce predicates. Keep in mind that for our purposes, predicates are always true statements about the world. If a predicate is not published it is presumed false.

It may be best to build custom launch files for the different predicator modules instead of launching with rosrun since each module needs to be carefully configured.

Querying Predicator

The Predicator core just aggregates predicates from a number of different topics.

Predicator works through a few different services, described below.

Instructor Support

Instructor plugins are in the predicator_plugins package. The user interfaces may require predicator_core to be running to get a list of possible predicates.

Provided Services

• predicator/test_predicate: determines if a predicate is true
• predicator/get_assignment: return the set of possible values for a single missing field
• predicator/get_possible_assignment: list the set of all possible values, if you provide an empty id. List of all possible values for a valid single-term predicate (a type) if you provide an id.
• predicator/get_predicates: list the set of all predicates currently considered valid
• predicator/get_value_predicates: list values published by Predicator modules
• predicator/update_param: manually set a predicator or remove a predicate; these are intended to be parameters that can be fixed and updated dynamically.
• predicator/get_sources: list the possible sources, the ROS nodes that Predicator has heard from
• predicator/get_predicate_names_by_source: list the names of predicates from each source ROS node
• predicator/get_all_predicates_by_source: return a list of all predicates that might be valid, and a truth assignment, for a given source
• predicator/get_assignment_names_by_source: list the assignments to the predicate produced by a given source
• predicator/get_predicate_names_by_assignment: list the possible predicates for a given assignment, based on ValidPredicates messages received. Will only report predicates reported from one source.
• predicator/get_assignment_length returns the number of parameter assignments for a given predicate, if available. Returns -1 if no length has been reported.

Common usage is to call test_predicate with a certain predicate to see if it exists, or get_assigment with a certain predicate to see what possible values there are for one of its arguments. To use get_assignment in this way, fill out a predicator_msgs::PredicateStatement object, but replace one argument with an asterisk (*). Predicates will be returned for all possible values of this argument.

I provided a helper function in get_possible_assignments for one-parameter predicates, which returns all possible values as a string. This is used for classes (ex: getting all possible locations or objects).

Getting all matches to a predicate

$ rosservice call predicator/get_assignment "statement:
  predicate: 'is_closed'
  value: 0.0
  confidence: 0.0
  num_params: 0
  params: ['*', '', '']
  param_classes: ['']" 
found: True
values: 
  - 
    predicate: is_closed
    value: 0.0
    confidence: 0.0
    num_params: 0
    params: ['wam2', '', '']
    param_classes: []

Getting a list of sources

$ rosservice call predicator/get_sources
data: ['/predicator_fake_class_node', '/predicator_wam2_joint_states_node', '/release_collab_frame2_creator', '/predicator_robot_interaction_node', '/predicator_geometry_node', '/predicator_wam_joint_states_node', '/collab_frame2_creator', '/predicator_movement_node', '/drop_points_publisher']

Getting predicates by source

$ rosservice call predicator/get_predicate_names_by_source "id: '/predicator_wam2_joint_states_node'" 
data: ['is_closed']

Getting assignments by source

$ rosservice call predicator/get_assignment_names_by_source "id: '/predicator_wam2_joint_states_node'" 
data: ['wam2']

Getting all predicates by source

This is an example from the peg demo.

$ rosservice call predicator/get_all_predicates_by_source "id: '/predicator_wam2_joint_states_node'" 
predicates: 
  - 
    predicate: is_closed
    value: 0.0
    confidence: 0.0
    num_params: 1
    params: ['wam2', '', '']
    param_classes: []
is_true: [True]

Note that since Predicator doesn't use class information, not all predicates produced by this are guaranteed to be valid!

Getting assignment length for a predicate

$ rosservice call /predicator/get_assignment_length "predicate: 'is_closed'" 
length: 1

Modules

Predicator modules are the ROS packages that actually perform some kind of analysis and publish that analysis as predicates. They are the source of all information used by Predicator.

List of Modules

• predicator_dummy_module: publishes a bunch of dummy information for testing purposes
• predicator_collision: collisions between objects; uses URDFs of objects to determine spatial relationship information.
• predicator_geometry: determine object spatial relationships based on positions (TF frames).
• predicator_occupancy_module: select a volume, determine if anything enters that volume.
• predicator_fake_classification: publish known object class information. For use with a simulator, when a real object detector isn't in use.
• predicator_movement: publish movement information, such as whether an object is approaching another object.
• predicator_params: provides a service so that you can set predicates at runtime to save information [REMOVED 2014-08-11].
• predicator_planning: computes many of the same predicates as predicator_geometry and predicator_collision, but also offers a simple randomized motion planning service that attempts to satisfy or negate predicates.

Module Setup

Geometry Module

Nodes like the predicator_geometry module can be configured from the ROS parameter server. It may be best to start them from a launch file, like the example launch file in predicator_geometry/launch/pegs_geometry_predicates_test.launch.

<node name="predicator_geometry_node"
  type="predicator_geometry_node.py"
  pkg="predicator_geometry"
  output="$(arg output)">

  <param name="height_threshold" value="0.1"/>
  <param name="rel_x_threshold" value="0.1"/>
  <param name="rel_y_threshold" value="0.1"/>
  <param name="rel_z_threshold" value="0.1"/>
  <param name="near_2D_threshold" value="0.2"/>
  <param name="near_3D_threshold" value="0.25"/>

  <rosparam param="frames">
    - ring1/ring_link
    - peg1/peg_link
    - peg1/base_link
    - peg2/peg_link
    - peg2/base_link
    - wam/shoulder_yaw_link
    - wam/shoulder_pitch_link
    - wam/upper_arm_link
    - wam/forearm_link
    - wam/wrist_yaw_link
    - wam/wrist_pitch_link
    - wam/wrist_palm_link
    - wam2/shoulder_yaw_link
    - wam2/shoulder_pitch_link
    - wam2/upper_arm_link
    - wam2/forearm_link
    - wam2/wrist_yaw_link
    - wam2/wrist_pitch_link
    - wam2/wrist_palm_link
    - stage_link
  </rosparam>
</node>

Writing a Module

Start with:

catkin_create_pkg predicator_custom_module predicator_msgs

New modules should publish a list of predicates (a predicator_msgs/PredicateList message) to the appropriate topic. By default, predicator_core will listen to the predicator/input topic for information from modules.

Modules need to set the pheader.frame_id field to their node name, indicating where messages are coming from.

Creating a Predicate

Create a predicator_msgs::PredicateStatement object and add it to the list of items in the predicator_msgs::PredicateList published by each module.

Make sure to fill out the fields:

• predicate: the name of the predicate to publish
• params: 3-tuple containing the arguments to this predicate
• num_params: number of these parameters you are actually using
• param_classes: descriptions of the parameters you are using (i.e., "object", "robot" -- class information)
• confidence: how accurate this predicate is believed to be (currently not really used for anything)
• value: the value associated with a predicate.

Boolean predicates can be given the values predicator_msgs::PredicateStatement::TRUE, predicator_msgs::PredicateStatement::FALSE, and predicator_msgs::PredicateStatement::UNKNOWN.

Specifying Valid Predicates

You can send a predicator_msgs::ValidPredicates object to help specify what types of predicates your modules can publish that are valid.

Fill out the following fields:

• assignments: the possible parameter arguments to your predicates (a union of any predicates you publish)
• predicates: the normal, boolean predicates you send out
• valid_predicates: floating point valued features such as distance, etc. that your module may compute.

Look at predicator_dummy_module for an example of how a module should publish predicate statements.

Contact

CoSTAR is maintained by Chris Paxton (cpaxton3@jhu.edu)