Scratch4Robots

Introduction

This tool allows to program complex robots like TurtleBot or drones with the visual language Scratch. Regular blocks from Scratch can be used in applications with Scratch2JdeRobot. In addition several blocks for some robots have been also created and can be included in the applications.

Blocks included in Scratch

Name	Type	Description
Wait () secs	Control Block	Pauses the script for the amount of time.
Forever	Control Block	A loop that will never end.
if () then	Control Block	Checks the condition so that if the condition is true, the blocks inside it will activate.
if () Then, Else	Control Block	Checks the condition so that if the condition is true, the blocks inside the first C will activate and if the condition is false, the blocks inside the second C will activate.
Repeat ()	Control Block	A loop that repeats the specified amount of times.
say ()	Looks blocks	Print what you enter as parameter.
Set () to ()	Variable blocks	Sets the specified variable to the amount.
Insert () at () of ()	List blocks	Insert item in the selected position of indicated list.
Item () of ()	List blocks	Returns the item stored in the indicated position.
Add () to ()	List blocks	Insert item in the list.
Delete () of ()	List blocks	Remove the item stored in the indicated position.

Blocks for drones

Name	Type	Inputs	Outputs	Description
Pose3D	Perceptive		XYZ Position	Get the value of the robot 3D position.
Color detection	Perceptive	Color	SIZEimg, Ximg, Yimg	Colored object in image.
Stop robot	Motion			Reset all velocity values.
Drone Take Off	Motion			Makes the drone take off.
Drone Land	Motion			Makes the drone land.
Drone Move	Motion	direction: (forward, back, up, down, left, right), speed: {velocity (integer)}		Gives the drone a speed in the indicated direction.
Drone Turn	Motion	direction: (left, right), speed: {velocity (integer)}		Gives the drone a turning speed in the indicated direction.

Blocks for TurtleBot

Name	Type	Inputs	Outputs	Description
Pose3D	Perceptive		XYZ Position	Get the value of the robot 3D position.
Color detection	Perceptive	Color	SIZEimg, Ximg, Yimg	Colored object in image.
Frontal Distance	Perceptive		The average measure of the frontal laser data	Get the average value for the values of the frontal laser
Robot Move	Motion	direction: (forward, back, left, right); speed: (integer)		Gives a speed in the indicated direction
Robot Turn	Motion	direction: (left, right); speed: (integer)		Gives a turning speed in the indicated direction
Drone Move to Position	Motion	direction: (forward, back, left, right); meter: (integer)		Move robot the indicated meters in one direction

Prerequisites

Scratch 2.0

Download the scratch file from here and then double click to install it.

wget -O adobe-air.sh http://drive.noobslab.com/data/apps/AdobeAir/adobe-air.sh
chmod +x adobe-air.sh; sudo ./adobe-air.sh

ROS

Follow the ROS tutorial installation.

Python requirements

git clone https://github.com/JdeRobot/Scratch4Robots
cd Scratch4Robots
pip install -r requirements.txt

Gazebo and worlds

Follow the Gazebo tutorial installation.

With this line we get some prepared worlds based on ROS ready to use:

sudo apt-get install ros-${ROS_DISTRO}-kobuki-gazebo

Installing

Check out the full installation video.

Install out ROS package

sudo apt-get install ros-kinetic-scratch4robots

Install Scartch4Robots extension to use in Scratch

In scratch keep pressing shift key while you click on “File” > “Import experimental HTTP extension” and add our extension. The extension will be stored in the “extension” directory of your package.

Note: This step is necessary each time you initialize Scratch

Download the tool from git

git clone https://github.com/JdeRobot/Scratch4Robots.git

Now your package is ready to use.

How to Use

Make a scratch project and save it.
Make the translation from Scratch to Python. Generate the code:
```
  rosrun scratch4robots scratch2python /path/to/your/scratchproject.sb2
```
This command will generate the python script on your current work directory.

Launch the simulated world. For example:

  roslaunch kobuki_gazebo kobuki_empty_world.launch --screen

Execute the generated code. The generated code need a configuration file .yml as parameter, you will find some usefull configuration files in our git repository.
```
  ./myscratchfile.py /path/to/robot_ros.yml
```
Running an example. You have all you need for running the examples in the examples folder.

How is this tool built?

Translation from Scratch to Python

To perform the block translation we use the Scratch2python.py script that parse our blocks replacing them with their corresponding code in Python. This script uses kurt library to load the scratch project.

How to add a new Scratch block to the extension

Add block code to scratch2robot.s2e.

["", "move robot %m.robotDirections meters %n", "robot/move/meters", "forward", 1],
["r", "size of object", "camera/size"],
["r", "x position of object", "camera/x_pos"],
["r", "y position of object", "camera/y_pos"],

Add block code to scratch2python.py.

['move robot {} meters {}', 'robot.move_meters("%s", %s)'],
['size of object', 'robot.get_size_object()'],
['x position of object', 'robot.get_x_position()'],
['y position of object', 'robot.get_y_position()'],

Add block code to robot.py or drone.py.

def move_meters(self, direction, meters=None)
    //code  

def get_size_object(self):
    //code
    return size

 def get_x_postion(self):
     //code
     return x_position

 def get_y_position(self):
     //code
     return y_position

Add block code to kurt extension in commands_src_extras.py.

[' ', 'move robot %m.robotDirections meters %n', 'Scratch2JdeRobot/robot/move/meters', 'forward', 1],
['r', 'size of object', 'Scratch2JdeRobot/camera/size'],
['r', 'x position of object', 'Scratch2JdeRobot/camera/x_pos'],
['r', 'y position of object', 'Scratch2JdeRobot/camera/y_pos'],

Note: You can find more information about how to create a extension in ExtensionDoc.