ros_first_steps

ros_first_steps is a ROS package with the aim of creating a node capable of interacting with turtlesim and making drawings of figures through coordinates obtained through files.

Installation

This package works on Kinetic version of ROS.

ROS installation

First of all you need to have installed this distribution.

Here is explained the instructions to install ROS kinetic on Ubuntu 15.10 and Ubuntu 16.04 if you don't have already installed it.

Once you completed the previous tutorial you can continue

Do not forget to source your installation path so you can have acces to the ROS commands.

$ source /opt/ros/kinetic/setup.bash

You will need to run this command on every new shell you open to have access to the ROS commands, unless you add this line to your .bashrc

Worskpace

If you already have a worskpace created jump to the next step.

Create your catkin workspace:

$ mkdir -p ~/catkin_ws/src
$ cd ~/catkin_ws/
$ catkin_make

This will generate serveral files. You will need to source another file too.

$ source devel/setup.bash

As said before, if you don't want to run this command on every shell you open you should add this line to your .bashrc.

For more details about the creation of a workspace you could check Create a ROS workspace page.

Packages needed

This package uses both the rqt and turtlesim packages. Please install both packages, if you have not yet done so.

$ sudo apt-get install ros-kinetic-rqt ros-kinetic-rqt-common-plugins ros-kinetic-turtlesim

Install ros_first_steps package

To install this package and use it you have two options to do that. You can either download the package and paste all the files in $YOUR_WORSKPACE/src/ros_first_steps or you can git clone the repository from the /src path.

$ cd ~/catkin_ws/src
$ git clone https://github.com/ekumenlabs/ros_first_steps

Finally you should run a make to generate the necessary files

$ cd ~/catkin_ws
$ catkin_make

Usage

There is a fully configured ROS Launch file so that when executing it, the necessary nodes are started.

It executes:

roscore
turtlesim_node
move_turtle_node (ros_first_steps's node)
rqt_reconfigre

Speed is a parameter and rqt_reconfigure is exectued because you need this to dynamically change turtle's speed.

Inside the figures folder there are 3 files that correspond to 3 different figures. You can add more files to draw other figures.

To start, you shall execute the following line:

$ roslaunch ros_first_steps movingturtle.launch

This command line will start all the files needed and draw a five-point star.

If you want to draw another figure you have to specify the path of that file. It will draw the figure located in ros_first_steps/figures/figure1.yaml if you do not specify a path.

$ roslaunch ros_first_steps movingturtle.launch figure:=<PATH>

This will draw the figure described from the coordenates within that file.

For example:

$ roslaunch ros_first_steps movingturtle.launch figure:=/home/$USER/catkin_ws/src/ros_first_steps/figures/figure2.yaml

This will draw the figure located in figure2.yaml.

Three figures are shared as examples. These are found within /ros_first_steps/figures.

When the turtle finishes the drawing node will be terminated.

Speed parameter

With the rqt window you can change the speed of the turtle.

Play or Pause Service

The node runs a service for pausing or resuming the movemente of turtle.

This service is called /playpause and it take one argument:

$ rosservice call /playpause pause

For pausing the movement.

$ rosservice call /playpause play

For resuming the movement and complete the remaiging path.

Add a coordinates file

If you want to draw another thing you always can make a file following this rules:

YAML format
Group of coordinates named as points
Max value of X or Y is 10
Min value of X or Y is 0

Example:

points:
-
  x: '6.5'
  y: '7.0'
-
  x: '10.5'
  y: '7.0'
-
  x: '7.5'
  y: '5.0'
-
  x: '8.5'
  y: '1.0'
-
  x: '5.5'
  y: '3.8'

It is neccesary to use a file extension such as .yaml

Here is an useful program where you can draw something and convert it to coordinate. Note: It ONLY works on Windows SO.

And if you need to transform your points from csv to yaml here is website where you can do it online:

Roadmap

The idea of this project is to continue with the following statements:

Implement a pid controller for the turtle, to improve the accuracy of the turtle when drawing at high speeds.
Add in the yaml file the possibility to change the background color or the color and thickness of the pen. (It's almost complete)
Add that you can draw in a window the route you want to do and that the turtle copy it.

Contributing

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.

Please make sure to update tests as appropriate.

francocipollone/ros-first-steps