Learning by demonstration GUI for TIAGo

GUI that enables the user to create a new upper body motion by using learning by demonstration with TIAGo that can be then played back with the ROS play_motion package.

Requirements

Some parts of the learning-by-demonstration software can only be run with a real TIAGo robot. This documentation describes the procedure to use this software with a real robot. Note that a computer installed with the TIAGo official development ISO is required.

In case of testing this software in the simulation of TIAGo please refer to the on-line tutorial in

How to run it

In order to run the learning-by-demonstration software with a real TIAGo follow the next steps.

Installation

Create, populate and build the required catkin workspace as follows:

$ mkdir -p ~/learning_ws/src
$ cd ~/learning_ws/src
$ git clone https://github.com/pal-robotics/simple_learning.git
$ git clone https://github.com/pal-robotics/learning_gui
$ cd ..
$ catkin build

Deployment and execution in the robot

The simple_learning package needs to be deployed in the robot as follows:

$ cd ~/learning_ws
$ rosrun pal_deploy deploy.py --user pal --package simple_learning tiago-Xc

where the X in tiago-Xc is the serial number of the robot without leading 0s. Once the package is deployed in the robot run it as follows:

$ ssh pal@tiago-Xc
$ roslaunch simple_learning simple_learning_server.launch

Execution of the GUI

Open another terminal in the development computer and run the following instructions:

$ cd ~/learning_ws
$ source ./devel/setup.bash
$ export ROS_MASTER_URI=http://tiago-Xc:11311
$ rosrun learning_gui learning_gui.py

and the following GUI will show up:

Select joints

First of all select the joints that you want to include in the new motion. Click on the corresponding checkboxes at the right part of the GUI. Note that the joints are grouped in the following groups:

• Head
• Arm
• Torso
• End-effector

Then, if one of the joints of a group is selected, the reamining joints of that group are automatically selected too.

Recording a motion

There are two ways of recording the new motion:

• Continuous recording
• Waypoint recording

In the Continuous recording mode the /joint_states topic is stored continuously while in the waypoint recording mode the user specifies at what instants of time the values in the /joint_states topic are recorded.

The continuous recording mode leads to a motion which will be very similar to the one taught by the user as many samples of the kinematic configuration will be recorded and the resulting speed of execution will be the same. The drawback of this mode is that any pause made by the user during the motion creation will be also recorded.

On the other hand, with the waypoint recording mode the user will need to specify how much time the robot will have for going from one sample point to another via interpolation, so that the resulting motion speed will depend on this parameter and on how far away are each consecutive sampling points. The main advantage of this mode is that delays made by the user during the motion definition are not recorded.

Continuous recording mode

First press the START CONTINUOUS RECORDING button. Note that this action will disable the waypoint recording mode as they cannot be mixed. The user can then start moving the upper body of the robot to teach the new motion in two ways:

• Moving individual joints using the sliders in the GUI: all the joints of the upper body can be moved. It requires that the control mode is set to Position.
• Moving the arm by kinesthetic teaching: the first 4 arm joints can be physically maneuvered by the user when selecting the Gravity Compensation control mode. The remaining arm and upper body joints can be still moved using the sliders provided in the GUI.

In order to stop recording the motion press the STOP RECORDING button.

Waypoints recording

First of all edit the Seconds to reach each waypoint value so depending on how far apart will be the waypoints you are going the record and the desired speed of the resulting interpolated motion.

Move the upper body to the first desired kinematic configuration by using the sliders and/or the kinesthetic teaching described before. Then press the RECORD CURRENT WAYPOINT in order to define the first position of the motion. Keep changing the kinematic configuration of the robot and recording waypoints as needed and finally press the STOP RECORDING button.

Playing back the recorded motion

Note that after pressing the STOP RECORDING button the following part of the GUI which was disabled will be ready to be used:

There are three different buttons to play back the recorded motion:

• Play 0.5X: plays back the motion at half the speed
• Play 1X: plays back the original recorded motion
• Play 2X: plays back the recorded motion at double speed

Exporting the recorded motion

The Save motion to file button allows the user to store the original motion to a yaml file which looks like as follows:

play_motion:
  motions:
    LBD_1X:
      joints: [arm_1_joint, arm_2_joint, arm_3_joint, arm_4_joint, arm_5_joint, arm_6_joint,
        arm_7_joint, torso_lift_joint, gripper_left_finger_joint, gripper_right_finger_joint]
      meta: {description: LBD_1X, name: LBD_1X, usage: demo}
      points:
      - positions: [1.6101164490941724, -0.9301305388945986, -3.140345763855865, 1.830050845009127,
          -1.5770101718438978, -0.6199711462955861, -1.5769827790865427, 0.295996401282352,
          0.04393598728391329, 0.04409034002067276]
        time_from_start: 0.0
      - positions: [1.6099937290033595, -0.9298237386675665, -3.1397935234472074,
          1.8298360848502049, -1.5770101718438978, -0.6200304972698552, -1.5769142971931556,
          0.2958400168895144, 0.04393598728391329, 0.04409034002067276]
        time_from_start: 4.0
      - positions: [1.6100397490374143, -0.9300384988264891, -3.1397781834358556,
          1.8298360848502049, -1.5770101718438978, -0.6200350627294142, -1.5769645172483062,
          0.2958400168895144, 0.04393598728391329, 0.04409034002067276]
        time_from_start: 8.0
      - positions: [1.6100704290601175, -0.9299617987697311, -3.139977603583427, 1.8300048249750724,
          -1.5770101718438978, -0.6200076699720594, -1.5769645172483062, 0.2959182090859332,
          0.04393598728391329, 0.04409034002067276]
        time_from_start: 12.0

This motion can be renamed by editing the tag LBD_1X. The motion stored in the yaml file, i.e. imagine it has been saved as new_motion.yaml, can be loaded in the rosparam server whenever needed as follows:

rosparam load new_motion.yaml

Then the motion can be played through the following Action interface:

/play_motion