Human Robot Collaboration

Repository that hosts software libraries and ROS packages for reproducing Human-Robot Collaboration experiments performed at the Social Robotics Lab in Yale University.

The software in this repo has been developed for, and tested on, a Baxter Research Robot---a widely used platform for research in HRC. Nonetheless, it is easy to customize to any robotic platform that shares similar hardware features and is provided with a kinematic model in URDF form. If you are using this software and or one of its components, we warmly recommend you to cite the following paper:

[Roncone2017] Roncone Alessandro, Mangin Olivier, Scassellati Brian Transparent Role Assignment and Task Allocation in Human Robot Collaboration IEEE International Conference on Robotics and Automation (ICRA 2017), Singapore. [PDF] [BIB]

Installation, Compilation and Testing

To install, compile and test this software, please refer to the installation tutorial.

Tested environments

ROS distro	Ubuntu Distro	Compiler	Status
indigo	14.04 Trusty	gcc-4.9	working
indigo	14.04 Trusty	clang-3.6	wontfix
kinetic	16.04 Xenial	gcc	disabled
kinetic	16.04 Xenial	clang	disabled

NOTE1: Apparently, it is very difficult to make clang work with Ubuntu 14.04 Trusty, C++14 enabled, and all of the old ROS libraries (indigo, OpenCV2.4, etc). I disabled compilation because I would rather prefer using the latest C++14 features. NOTE2: As of today (June 7th 2017), kinetic builds are disabled, since travis does not support Ubuntu 16.04 Xenial Xerus yet. 16.04 support should come on Q2 2017.

Execution on the robot

Initial steps (mainly for Scazlab students)

0. Turn on the robot. Wait for the robot to finish its start-up phase.
1. Be sure that the system you're running the code has access to the Baxter robot. This is usually done by running the baxter.sh script that should be provided in your Baxter installation. See here for more info. @ScazLab students → for what concerns the Baxter robot on the ScazLab, this means that every time you have to run some ROS software to be used on the robot you should open a new terminal, and do the following: cd ros_devel_ws && ./baxter.sh. A change in the terminal prompt should acknowledge that you now have access to baxter.local. Please be aware of this issue when you operate the robot.
2. Untuck the robot. @ScazLab students → we have an alias for this, so you just have to type untuck

This repository currently allows for two modes of operation:

1. A. Cartesian Controller server → It allows for controlling each of the arms in operational space.
2. B. High-level actions → It enables some high-level actions to be asked to the robot, such has hold or pick object.

These two modes can be enabled concurrently, but this feature is disabled by default: in order to be able to communicate with the robot both in the high-level interface and the low-level controller, you need to create your own action_provider. See the src folder for more information on that.

Mode A. Cartesian Controller Server

In this mode, the user can ask the robot to go to a specific 3D Position or 6D Pose (position + orientation), and the robot will simply go there (if physically possible). To guarantee safety, the robot still has the standard safety systems enabled by default. More advanced uses are allowed, but not exposed to the user: if you want to tinker with advanced features, we recommend to specialize the RobotInterface class.

In order to use the Cartesian Controller Server, you have to launch it with:

roslaunch human_robot_collaboration baxter_controller.launch

This should create two topics the user can request operational space configurations to. They are /baxter_controller/left/go_to_pose for left arm, and /baxter_controller/left/go_to_pose for right arm. In the following, there are some examples on how to require them from terminal (e.g. for the left arm):

• [6D Pose] : rostopic pub /baxter_controller/left/go_to_pose human_robot_collaboration_msgs/GoToPose "{pose_stamp: {pose:{position:{ x: 0.55, y: 0.55, z: 0.2}, orientation:{ x: 0, y: 1, z: 0, w: 0}}}, ctrl_mode: 0}" --once
• [3D Position] : rostopic pub /baxter_controller/left/go_to_pose human_robot_collaboration_msgs/GoToPose "{pose_stamp: {pose:{position:{ x: 0.55, y: 0.55, z: 0.2}, orientation:{ x: -100, y: -100, z: -100, w: -100}}}, ctrl_mode: 0}" --once. This differs from the previous case since now every value of the orientation quaternion is set to -100. This is to communicate the Cartesian Controller to reach the desired position while maintaining the current orientation.

Obviously, these same messages can be sent directly within your code. Please take a look at the GoToPose.msg file for further info.

Mode B. High-Level Actions

We implemented a low-level, state-less controller able to operate each of the arms independently (and communicate with the other one if needed). A library of high-level predefined actions (in the form of ROS services) is available for the user to choose from; such actions range from the simple, single arm pick object to the more complex hold object (which requires a physical collaboration with the human partner) or hand over (which demands a bi-manual interaction between the two arms).

To enable this mode, run roslaunch human_robot_collaboration flatpack_furniture.launch or roslaunch human_robot_collaboration modular_furniture.launch. These are two predefined launch files that we use for two different experiments we ran in the lab. If you would like to create and use your own high-level actions, we suggest you to specialize the ArmCtrl class. See the flatpack_furniture library for inspiration on how to do it.

Now, the user should be able to request actions to either one of the two arms by using the proper service (/action_provider/service_left for left arm, /action_provider/service_right for right arm). Here are some examples to make the demo work from terminal:

• rosservice call /action_provider/service_right "{action: 'hold'}"
• rosservice call /action_provider/service_left "{action: 'get', objects: [17]}"

Similarly to Mode A, these same services can be requested directly within your code. Please take a look at the DoAction.srv file for further info.

Non-exhaustive list of supported actions

• list_actions (both arms): it returns a list of the available actions for the specific arm.
• home (both arms): moves the arm to a specific joint configuration (i.e. it does not use IK).
• release (both arms): opens the gripper (or releases the vacuum gripper).
• hand_over (both arms): performs an handover from the left to the right hand. The left arm picks an object up at a specific orientation (for now it works only with the central frame, ID number 24), and passes it to the right arm, which then holds it until further notice.
• get (left arm): the robot gets an object at a random orientation, and moves it on the table (without releasing it).
• pass (left arm): if the robot has an object in its vacuum gripper, it moves it toward the human partner and waits for force interaction in order to release the gripper. The force filter we applied is a low-pass filter, so in order to trigger the release action, the human is suggested to apply an high-frequency, spike-y interaction.
• hold (right arm): the robot moves into a configuration in which it is optimal to hold an object as a supportive action for the human partner. After that, it waits for force interaction to close the gripper, and again to open the gripper when the human has finished. See above for a description of the proper force interaction that should be applied to the arm in order to trigger the behaviors.

Python controller

The BaseController class abstracts python access to the robot resources, including the high-level action action_provider service. It is based on a few Python helpers for

• asynchronous service requests
• subscribers to wait for the next relevant message
• an experiment timer (mostly a log function that records times and can save to json)

Misc

• To kill an action from the terminal, you can simulate a button press on the arm's cuff: rostopic pub --once /robot/digital_io/left_lower_button/state baxter_core_msgs/DigitalIOState "{state: 1, isInputOnly: true}".
• You can also kill an action from the web interface, by pressing the ERROR button. It writes to the same topic and achieves the same behavior.
• To go robot-less (that is try to execute the software without the robot, for testing purposes), you can choose one of the following options:
• Call the action_provider with the argument --no_robot, e.g. rosrun human_robot_collaboration baxter_controller --no_robot. In this mode, only the service to request actions is enabled. It will always return with a 2s delay and it will always succeed.
• Change the use_robot flag to false in the launch file.
• Launch the launch file with the argument use_robot:=false, e.g. roslaunch human_robot_collaboration baxter_controller.launch use_robot:=false

Experiments

ICRA 2017

To reproduce the experiment from the following paper on the Baxter research robot, we provide the script human_robot_collaboration/scripts/icra_experiment.

[Roncone2017] Roncone Alessandro, Mangin Olivier, Scassellati Brian Transparent Role Assignment and Task Allocation in Human Robot Collaboration IEEE International Conference on Robotics and Automation (ICRA 2017), Singapore.

It needs to be given the path to an offline computed policy, as possible with github.com/ScazLab/task-models.