Backup of ROS integration(No. 2)

Tutorial?

The aim of this tutorial is to explain how to integrate SIGVerse with ROS operating system.

Ros tutorial on SIGverse

How to Use ROS with SIGverse
User has to create A SIGverse node using the following code:
- In this tutorial two topics are used
- Message Topic to send messages from SIGverse Node to Command Node and Velocity --format Topic to send the value of velocity to the SIGverse node.

Overview
Installing ROS
Creating SIGVerse Package
- Catkin Workspace initialization
Creating ROS Package
Source Code understanding
Running the server

Overview †

In order to integrate SIGVerse and ROS You need to build the following basic system. You first have to install ROS on your computer then build two ROS packages.

The first package will run with the SIGVerse Controller in order to perform the message reception from the SIGViewer and the robot motion with velocity command.
the second package will receive the messages and perform the correct command those two packages will contains nodes and will use two topics to perform comunication.
the first topic is used to send messages.
the second topic is used to feedback the command velocity.

↑

Installing ROS †

= Ubuntu install of ROS Groovy =

We are building Debian packages for several Ubuntu platforms, listed below. These packages are more efficient than source-based builds and are our preferred installation method for Ubuntu.

If you need to install from source (not recommended), please see groovy/Installation/Source|source (download-and-compile) installation instructions?.

=== Installation ===

First, make sure your Debian package index is up-to-date:

 $ sudo apt-get update

There are many different libraries and tools in ROS. We provided four default configurations to get you started. You can also install ROS packages individually.

 
  $ sudo apt-get install ros-groovy-desktop-full

  $ sudo apt-get install ros-groovy-desktop

ROS-Base: (Bare Bones)

ROS package, build, and communication libraries. No GUI tools.

 $ sudo apt-get install ros-groovy-ros-base

Individual Package:

You can also install a specific ROS package (replace underscores with dashes of the package name):

$ sudo apt-get install ros-groovy-PACKAGE

$ sudo apt-get install ros-groovy-slam-gmapping

To find available packages, use:

$ apt-cache search ros-groovy

=== Initialize rosdep ===

Before you can use ROS, you will need to initialize `rosdep`. `rosdep` enables you to easily install system dependencies for source you want to compile and is required to run some core components in ROS.

$ sudo rosdep init
$ rosdep update

=== Getting rosinstall ===

rosinstall? is a frequently used command-line tool in ROS that is distributed separately. It enables you to easily download many source trees for ROS packages with one command.

To install this tool on Ubuntu, run:

$ sudo apt-get install python-rosinstall

↑

Creating SIGVerse Package †

You need to create a new Ros Package to perform the ROS SIGverse integration

Let’s create a new directory named catkin_ws and let’s perform those few tasks

Create a new folder named src.

Now let’s initialize our workspace by using the following command:

↑

Catkin Workspace initialization †

 $catkin_init_workspace in the ~/catkin_ws folder

Now we have our workspace let’s create our SIGverse Package

Firstable we need to make a new folder named SIGverse then edit the Cmake file and Sig_app.cpp in a new src folder which PATH is:

 $~/catkin_ws/src/Sigvers_Ros/src.

$ cd ~/catkin_ws/src
$ catkin_create_pkg Sigvers_Ros

Now make Cmake file in order to create the wanted package. Catkin_make will generate a /devel folder which contains /devel/lib folder and in there the Cmake file generated a libSig_app.so file which will be used by the xml world file to control the robot simulation. Now let’s souce our package by using the following command:

  $source ~/catkin_ws2/devel/setup.sh

Now we can check our package by executing this command
- Roscd Sigvers_Ros so we get the following result:

CMakeLists.txt include msg package.xml src

This shows that the Sigvers_Ros packages exists

Cmake parameters: For Sig.cpp:

cmake_minimum_required(VERSION 2.8.3)
project(Sigvers_Ros)
 find_package(catkin REQUIRED COMPONENTS roscpp rospy std_msgs message_generation )

## Generate messages in the 'msg' folder
    add_message_files(
    FILES
    Velocity.msg
    )

 ## Generate added messages and services with any dependencies listed here
    generate_messages(
    DEPENDENCIES
    std_msgs
    )

 ADD_LIBRARY(Sig_app src/Sig_app.cpp)
 target_link_libraries(Sig_app ${catkin_LIBRARIES})
 add_dependencies(Sig_app Sigvers_Ros_gencpp)

We use the target_link_libraries which generates the .so file

 include_directories(include ${catkin_INCLUDE_DIRS})
 include_directories(/home/ericgt/sigverse-2.2.0/include/sigverse/home/ericgt/sigverse-2.2.0/include/sigverse/comm/controller)

Here you include SiGverse .h files to compile our controller’s source code Catkin Command:

catkin_make

we compile our code using Cmake parameters so we generate .so file used by the xml world file to control the robot simulation.

↑

Creating ROS Package †

↑

Source Code understanding †

Let’s study this example step by step Now let’s create the callback function which preforms the command on the velocity of the robot’s wheels:

↑

Message Sender †

  void SendController::poseCallback(const Sigvers_Ros::VelocityConstPtr& vel)
  {     Wheel_one =  vel->linear;
        Wheel_two =  vel->angular;
     
        printf("Velocity 1!!!  %f\n", Wheel_one);
        printf("Velocity 2!!!  %f\n", Wheel_two);
     
  }

read from the Velocity Topic
Printing the Velocity value applied on the robot

↑

Node Initialization †

 void SendController::onInit(InitEvent &evt)
  { Wheel_one = 0.0;
   Wheel_two = 0.0;
   int argc =0;
   char** argv = NULL;
   my = this->getRobotObj(this->myname());
   my->setWheel(10.0, 10.0);
   ros::init(argc, argv, "Sigvers_controller_node");
   ros::NodeHandle n;
   velocity = 1;
   chatter_pub = n.advertise<std_msgs::String>("CommandMess", 1);
   pose_sub = n.subscribe<Sigvers_Ros::Velocity>("mycommand_velocity",    1,&SendController::poseCallback,this);
   ros::Rate loop_rate(10);
  }

↑

Robot Controller †

double SendController::onAction(ActionEvent &evt)
{
 my->setWheelVelocity(Weel_one,Weel_two);
 ros::spinOnce();
 return 1.0;
}

Now let’s create a Node to control the robot’s velocity:

↑

Command Node initialization ROS Side †

 CommandSig::CommandSig():
  linear_(0),
  angular_(0),
  l_scale_(2.0),
  a_scale_(2.0)
  {
   nh_.param("scale_angular", a_scale_, a_scale_);
   nh_.param("scale_linear", l_scale_, l_scale_);
   vel_pub_ = nh_.advertise<Sigvers_Ros::Velocity>("mycommand_velocity", 1);
   mess_sub =    nh_.subscribe("CommandMess",100,&CommandSig::chatterCallback,this);
   
   }

Initialization of the command Node's Parameters

The Node will send velocity information using mycommand_velocity Topic

The Node will receive information using CommandMess Topic

And finally let’s write the main function which launches the command node

↑

Main to execute the Node †

int main(int argc, char** argv)
 {
  ros::init(argc, argv, "Sigvers_Command_node");
  CommandSig Command_sig;
  ros::Rate loop_rate(10);
  ros::spin();
  return(0);
 }

this command creates and does initialization on the Sigvers_Command_node Node

↑

Message Sender †

Now let’s create the callback function which receveces message from Sigverse - Node and sends the right command to the robot:

↑

Robot Motion Command ROS Side †

  void CommandSig::chatterCallback (const std_msgs::String::ConstPtr& msg)
  {
   Sigvers_Ros::Velocity vel;
   if(strcmp("go",msg->data.c_str())==0)
   {
   vel.angular = 3.0;
   vel.linear = 3.0;
   vel_pub_.publish(vel);
   }
   else if(strcmp("back",msg->data.c_str())==0)
  {
   vel.angular = -3.0;
   vel.linear = -3.0;
   vel_pub_.publish(vel);
   }
   else if(strcmp("left" ,msg->data.c_str())==0)
  {
  vel.angular = 0.78;
  vel.linear = -0.78;
  vel_pub_.publish(vel);
  sleep(1.8);
  vel.angular = 0.0;
  vel.linear = 0.0;
  vel_pub_.publish(vel);
  }
  else if(strcmp("right" ,msg->data.c_str())==0)
  {
  vel.angular = -0.78;
  vel.linear = 0.78;
  vel_pub_.publish(vel);
  sleep(1.8);
  vel.angular = 0.0;
  vel.linear =  0.0;
  vel_pub_.publish(vel);
  }
  else if(strcmp("stop",msg->data.c_str())==0)
 {
  vel.angular = 0.0;
  vel.linear = 0.0;
  vel_pub_.publish(vel);
 }
………
}

↑

Running the server †

To run the server you have to follow the following steps:

Go to catkin_ws and execute the follwing command :

Run the ROS system:
```
$ roscore
```
run the ros ROS node :

$ rosrun key_sig sig_app

Go to ~/catkin_ws/devel/lib/libsig_app and run the sigverse controller: $ cd ~/catkin_ws/devel/lib/libsig_app $ sigserver.sh -w ./move_robot.xml

Backup of ROS integration (No. 2)

Overview †

Installing ROS †

Creating SIGVerse Package †

Catkin Workspace initialization †

Creating ROS Package †

Source Code understanding †

Message Sender †

Node Initialization †

Robot Controller †

Command Node initialization ROS Side †

Main to execute the Node †

Message Sender †

Robot Motion Command ROS Side †

Running the server †