OBSTACLE AVOID FOR PR2

LASER OBSTACLE AVOIDANCE FOR PR2

One of the basic behaviour a budding roboticist often starts with is obstacle avoidance using sonar or laser scan. While playing with gazebo simulations, we realised that we are yet to try out a very basic laser obstacle avoidance behaviour in the PR2 robot employing the SICK laser. It was not long that we wrote our codes and made our ROS package and started with simulations in gazebo. A surprise awaited us ........

WHAT THE HELL !!!! 

We got an empty world with PR2 and then filled it up with boxes and set our code into action. Much to our surprise the PR2 robot did not try to avoid those boxes, but push them rather awkwardly. 

BOX PUSHING INSTEAD OF OBSTACLE AVOIDANCE

It was after few such 'failed attempts' and cursing our code incessantly that we realised that the issue is with the stretched out arms of the PR2. The distance for the obstacle avoidance to work is at min_range<=0.5, however we never had accounted for the PR2's arms while coding so the obstacle avoidance code is not coming to fore and is restricted by the arm lengths. Thus when the PR2 reaches the obstacle it continues to move and 'push' the obstacles, since gazebo is a physics based simulator thus in a box world it reflects such as a 'box pushing' behaviour. It may be said that such a behaviour arises in the 'emergent' context. Playing around with the code, we finally set it to, min_range<=1.2 which sorted out the issue.

The codes discussed here can be found at, https://github.com/Arkapravo/laser_obstacle_avoidance_pr2, feel free to write to us at Arkapravo Bhaumik (arkapravobhaumik at gmail dot com) and Koushik Kabiraj (koushik dot atti at gmail dot com).

TELEOPERATION IN GAZEBO

IROBOT CREATE MODEL IN GAZEBO

We have met the roomba robot in one of my previous articles. Here, I work on some simple teleoperation on it, this time with a 3 dimensional model in gazebo.

I am thankful to Jeff for providing a URDF for the irobot create at http://code.google.com/p/aptima-ros-pkg/ .

TELEOPERATION

I used this roomba model with simple_office.world, which is one of the environments provided by the installation files for gazebo. I was able to move the robot around using teleoperation from teleop_base. 
 

NOTE:

1. The simulations were done in ROS 1.4.10, Diamondback, installed on Ubuntu 10.04 LTS
2. The codes for the simulation are provided at https://github.com/Arkapravo/irobot_create_gazebo

USING GAZEBO

GAZEBO

 

Gazebo is a part of the Player Project. It is a 3D simulator utilising ODE and OGRE. ROS has incorporated Gazebo into their distributions with some minor modification.

GAZEBO@ROS WITH WORLD FILES - A DETOUR FROM THE USUAL

Gazebo, while it is a part of Player Project is used with world files. However, ROS recommend using Gazebo with launch files - these launch files identify the corresponding world file.

However in the spirit of Player/Stage/Gazebo it is possible to run Gazebo with world files from its executable, located at /opt/ros/diamondback/stacks/simulator_gazebo/gazebo/bin .

Thus using ./gazebo with pioneer2dx.world, which is a well known Player Project world file;

1. Start an instance of roscore - gazebo is built with slight modification, so an instance of master (roscore) is needed. The later scripts search for the master.
   
2. Navigate to the gazebo executables directory ( cd /opt/ros/diamondback/stacks/simulator_gazebo/gazebo/bin)  
3. Start Gazebo with pioneer2dx.world file (./gazebo /path/to/pioneer2dx.world)
4. The following window should pop up,  

Trying the rxgraph to check the ROS nodes at work;

Trying with pioneer2at.world file;

The same works for Stage, the executables at /opt/ros/diamondback/stacks/simulator_stage/stage/bin  can be used in a similar manner. The executables, stage and stageros work same with a world file giving 2D simulations. However stage is the primitive Player Project executable and doesn't need a roscore master while stageros is more 'ROS like', needs roscore and works with ROS nodes. 

NOTE 

1. Tested on ROS 1.4.9 Diamondback (Gazebo 0.10.0 and Stage 3.2.2)     
2. pioneer2dx.world and pioneer2at.world files can be found in Gazebo installation files (viz. gazebo-0.10.0/worlds)
3. An alternative is to use, rosrun gazebo gazebo /path/to/pioneer2dx.world file

REFERENCES

(1) I thank John Hsu for his help

(2) stage vs. stageros 

(3) launch files for gazebo

(4) N.Koenig, A.Howard,"Design and Use Paradigms for Gazebo, An Open-Source Multi-Robot Simulator"
(5) Gazebo Test at Care-O-Bot webpage 
(6) Alternative download form the pioneer2dx.world file - http://ubuntuone.com/5pWIiUyo1mhrY2PHP4I86C

INSTALLING PLAYER-STAGE : WHAT WORKED FOR ME

PLAYER/STAGE INSTALLATION GUIDE ON UBUNTU 9.04, 10.04 LTS AND 12.04 LTS

Player-Stage or as it is now know, Player Project is a very versatile software for robot simulation and hardware control interface. It primarily uses FLTK and OpenGL.

After trying various means and hopelessly failing, I successfully installed Player-Stage in Ubuntu 9.04 (and much later also on Ubuntu 10.04 - scroll down for that).

The following is a succinct of my efforts. 

INSTALLING PLAYER/STAGE IN UBUNTU 9.04 AND UBUNTU 10.04 LTS

The post primarily deals with installation in Ubuntu 9.04, for installation in Ubuntu 10.04 LTS and 12.04 LTS scroll down, close to the end of this post.  

THE INSTALLATION : IN 8 SIMPLE STEPS

#1.Update Ubuntu

A fresh installation of the OS (Ubuntu 9.04 ) is preferred.

Update Ubuntu 9.04 completely using sudo apt-get update and sudo apt-get upgrade. (Do not do a distribution update to Ubuntu 9.10 or higher)

#2.Install the dependencies

Dependencies for installation in Ubuntu 9.04;

sudo apt-get install autotools-dev build-essential cmake cpp libboost-signals1.35.0 libboost-signals1.35-dev libboost-thread1.35.0 libboost-thread1.35-dev libcv1 libcv-dev libgdk-pixbuf2 libgdk-pixbuf-dev libgnomecanvas2-0 libgnomecanvas2-dev libgsl0-dev libgtk2.0-dev libjpeg62-dev libtool libxmu-dev swig freeglut3 freeglut3-dev libfltk1.1 libfltk1.1-dev libltdl7 libltdl7-dev libpng12-0-dev libpng12-0

Make sure all these packages (or any alternative packages (hardly one or two) offered by Ubuntu 9.04 repositories, i.e. in case If libpng12-dev or any such package is not installed by apt-get, then install it manually) are installed. Run the above commands 2 to 3 times to confirm that these packages are indeed installed.

#3.Download the sources

Download Player-3.0.0 and Stage-3.2.0-Source and extract the files. Restart the computer for dependencies to come to effect.

#4.Configure and install player and stage in the $usr/local directory

Do not try to install Stage before installing Player. Stage installation script 'looks for' player installation

Installing Player

execute each of these commands (5 in total) one at a time in the same order as shown

cd player-3.0.0
mkdir build
cd build
cmake ../
make
sudo make install

Installing Stage

An Error in Stage files : Before installation, there is an error in Stage files that should be corrected, in the source code in the file Stage-3.2.0-Source/libstageplugin/p_driver.cc closer to the end of the file, Change the line : "world->Update();" to "Fl::wait();" . This error has been rectified in later versions of Stage (i.e. Stage-3.2.2 etc).

Now install, much like Player, execute each of these commands (4 in total) one at a time in the same order as shown.

cd Stage-3.2.0-Source
mkdir build
cd build
cmake ../
make
sudo make install

#5.Confirming the installation

#6.Setting the 'PATH'

In the 'home' folder enable 'show hidden files' and locate the .bashrc file.

At the end of the .bashrc file append the following.

PATH=$PATH:/usr/local/bin

LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib

PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/usr/local/lib/pkgconfig

export PATH

export LD_LIBRARY_PATH

export PKG_CONFIG_PATH

Then run the command source ~/.bashrc from the terminal, restart the computer

#7. Check !  

In the Stage installation files

cd Stage-3.2.0-Source/worlds

Start the simulation with,  player simple.cfg

If the following screen with a little red robot, pops up then everything is set up nicely !

#8. Check for compilation

In Player installation files, cd player-3.0.0/examples/libplayerc++ 

compilation command for sonarobstacleavoid.cc

g++ -o laserobstacleavoid `pkg-config --cflags playerc++` laserobstacleavoid.cc `pkg-config --libs playerc++` 

If it compiles without any errors then all is good ! .....

SMORGASBORD FOR PLAYER-STAGE

(i) 2.5 Dimension

To see your robot do a 2.5 Dimension, press 'R' (Perspective Camera) while the 2 Dimensional simulation is on !

(ii) Command line check for version

Simple command lines, to confirm the versions of Player and Stage;

(iii) robot-player from ubuntu repositories

In Ubuntu 10.04, one can install robot-player (sudo apt-get install robot-player) from the repositories and the package has been updated for recent versions of Ubuntu, however I faced C++ compilation issues with it.

(iv) Working with a virtual OS

If you are working in a virtual box virtual machine then there may be issues in controlling the robot hardware as hardware layer abstraction is not fully supported. However, simulation in stage is fine.

If you are working on Virtual Box then do Install Guest Additions (This will help to maximise the screen and seamlessly integrate the guest OS with host OS).

(v) 'flickering' in Stage

If Stage starts to flicker too much, then put the 'Visual Effects' in Ubuntu 9.04 to None.

(vi) Recording a video of the simulation

If required, the simulation may be recorded as a video using tools as Record MyDesktop, and then converting the ogg files to to to avi using MEncoder .

(vii) Mailing list and support 

As Player-Stage newbie, one may consider joining the official mailing list and/or the facebook page. 

(viii) Any other success story ? 

This installation also works with Player-3.0.1 and Stage-3.2.0.

I recently tried an overwrite of the player with the latest svn, revision 8767 (3.1.0-svn) and that worked.

However, do not try an overwrite of Stage. 

(ix) Gazebo installation

I have got a few enquiries about Gazebo ! .... and here is my response ! 

I could not install Gazebo, few attempts with version 0.10.0 conflicted with my Stage installation.

I installed ROS in order to work with Gazebo (version 0.9.0). ROS is a another Robotics suite and it uses Stage, Gazebo and a host of other softwares. However the working and command structure are much different from that of Player-Stage.

ROS is a way to use Gazebo without the hassles of bindings etc. A word of advice, ROS recommends Ubuntu 9.10 for installation. So this installation (recommended for Ubuntu 9.04) of Player-Stage may not work in tandem with ROS.

 

In Ubuntu 10.04 LTS, ROS can be installed side by side with Player/Stage without any issues of conflict etc.

For more on ROS and Gazebo - see my article on using gazebo.

 
(x) New drivers

For the adventurous coders, who plans to design new player drivers - have a look at these tutorials,

#. Player wiki

#. Tutorial at Pennsylvania State University

#. Tutorial at University of Copenhagen

#. Tutorial at Aalborg University

(xi) New home for the project at github

The project has found a new home at github. Stage 4.0.0 was released on 26 November 2010.

It is worth noting that Stage 4.X.X has back compatibility issues with Stage 3.X.X. Have a look at, Moving from Stage 3 to Stage 4: laser and ranger .

(xii) Installation on Ubuntu 10.04 LTS 

I was able to install Player-3.02 and Stage-3.2.2 on Ubuntu 10.04 LTS, I used the following tutorials;

#. Tutorial 1 - in German

#. Tutorial 2 - more suited to Ubuntu 10.10, but some tips well apply to Ubuntu 10.04

#. Tutorial 3 

 

The major change from installation in 9.04 is the dependencies; rest of the installation is same as that for 9.04.

Dependencies for installation in Ubuntu 10.04;

sudo apt-get install autotools-dev build-essential cmake cpp libboost-python1.40.0 libboost-python1.40-dev libboost-thread-dev libboost-signals1.40.0 libboost-signals1.40-dev libcv4 libcv-dev libgdk-pixbuf2-ruby libhighgui-dev libgnomecanvas2-0 libgnomecanvas2-dev  libgsl0ldbl libgsl0-dev libjpeg62-dev libtool libxmu-dev swig freeglut3 freeglut3-dev libfltk1.1 libfltk1.1-dev libgtk2.0-dev libltdl7 libltdl7-dev libpng12-0 libpng12-dev libcvaux4 libcvaux-dev libltdl-dev libguile-ltdl-1 fluid glutg3-dev freeglut3 freeglut3-dev libart-2.0-2 libatk1.0-0 libboost-thread1.40.0 libboost-thread1.40-dev libc6 libcairo2 libcv4 libcv-dev libcvaux4 libfontconfig1 libfreetype6 libgcc1 libgl1-mesa-glx libglib2.0-0 libglu1-mesa libglu1 libgnomecanvas2-0 libgsl0ldbl libgsl0-dev libgtk2.0-0 libhighgui4 libjpeg62 libjpeg62-dev liblodo0 libltdl7 libpango1.0-0 libplayerc++2 libplayerc2 libplayercore2 libplayerdrivers2 libplayererror2 libplayertcp2 libplayerxdr2 libpmap0 libstdc++6 zlib1g libxmu-dev

(xiii) A vmdk FOR PLAYER/STAGE AND ROS

I have recently made available a vmdk which has Player 3.0.2, Stage 3.2.2 and ROS (Electric) pre-installed.

http://mobotica.blogspot.in/2012/09/a-vmdk-for-ros-electric.html

(xiv) Installation on Ubuntu 12.04

Using Kevin's article I was able to install Player 3.0.2 and Stage 3.2.2 on Ubuntu 12.04 LTS (32 Bit). 

Note for installation in Ubuntu 12.04

Kevin has mentioned that, for installation in Ubuntu 12.04 if Stage compilation gives the following error;

To correct this error you need to make the following changes in CMakeLists.txt where lines

SET (CMAKE_CXX_FLAGS_RELEASE " -O3 -DNDEBUG ${WALL} " CACHE INTERNAL "C Flags for release" FORCE) 

SET (CMAKE_CXX_FLAGS_DEBUG " -ggdb ${WALL} " CACHE INTERNAL "C Flags for debug" FORCE) 

SET (CMAKE_CXX_FLAGS_PROFILE " -O3 -ggdb -pg ${WALL} " CACHE INTERNAL "C Flags for profile" FORCE)

Needs to be changed to,

SET (CMAKE_CXX_FLAGS_RELEASE " -O3 -DNDEBUG -Wl,--no-as-needed" CACHE INTERNAL "C Flags for release" FORCE) 

SET (CMAKE_CXX_FLAGS_DEBUG " -ggdb -Wl,--no-as-needed " CACHE INTERNAL "C Flags for debug" FORCE) 

SET (CMAKE_CXX_FLAGS_PROFILE " -O3 -ggdb -pg -Wl,--no-as-needed " CACHE INTERNAL "C Flags for profile" FORCE)

 
REFERENCES AND INSTALLATION GUIDES FOR OTHER OS

(1)  Aalborg University Wiki

(2)  Aalborg University Script

(3)  Player-Project

(4)  Standard UNIX installations

(5)  Player-Stage, openSUSE installation

(6)  Jennifer Owen's page

(7)  i-phone player/stage

(8)  Mac (10.6.2) installation

(9)  Playing with Player Project
(10) Installing Player on Raspberry-Pi

(11) github page for Stage 4.X.X

(12) Ubuntu 10.10 installation 

(13) Ubuntu 11.04 installation

(14) Ubuntu 11.10 installation  

(15) Ubuntu 12.04 installation