Creating a ROS Package and C++ Node to Drive the iRobot Create

Today I'm going to go through the process I went through to create a simple node to drive the iRobot Create. I discussed last post how to get the driver for iCreate working in ROS Hydro. I want to make a package which contains a program that will allow me to drive the create using the w, a, s, and d keys on my keyboard. To get started, I need to navigate to my ROS workspace. Don't forget to source your ROS and ROS workspace settings.
source /opt/ros/hydro/setup.bash
source ~/catkin_ws/devel/setup.bash     # my workspace location

Now, in the workspace directory:
cd ~/catkin_ws/src  # navigate to my workspace src directory
catkin_create_pkg robot_mover geometry_msgs std_msgs genmsg      roscpp rospy
cd .. # return to workspace directory to make
catkin_make

Now, to create the program:
roscd robot_mover/src
gedit keyboard_mover.cpp

Inside of keyboard_mover file I used the following code, modified from here:

#include <iostream>
#include <stdio.h>
#include <ncurses.h>

#include <ros/ros.h>
#include <geometry_msgs/Twist.h>

class RobotDriver
{
private:
  //! The node handle we'll be using
  ros::NodeHandle n_;
  //! We will be publishing to the "/base_controller/command" topic to issue commands
  ros::Publisher cmd_vel_pub_;

public:
  //! ROS node initialization
  RobotDriver(ros::NodeHandle &n)
  {
    n_ = n;
    //set up the publisher for the cmd_vel topic
    cmd_vel_pub_ = n_.advertise<geometry_msgs::Twist>("/cmd_vel", 1);
  }

  //! Loop forever while sending drive commands based on keyboard input
  bool driveKeyboard()
  {
    std::cout << "Type a command and then press enter.  "
      "Use 'w','a','s', and 'd' to navigate and 'q' to exit.\n";

    //we will be sending commands of type "twist"
    geometry_msgs::Twist base_cmd;

    char cmd;
    initscr(); //get terminal environment variables
    cbreak();  //line buffering disabled; pass on everything
    timeout(1000);  //getch blocks for 1 second

    while(n_.ok()){

      cmd = getch();

      if(cmd !='w' && cmd !='a' && cmd !='s' && cmd !='d' && cmd !='q' && cmd != 'e' && cmd != -1)
      {
        std::cout << "unknown command...\n\r";
        continue;
      }

      base_cmd.linear.x = base_cmd.linear.y = base_cmd.angular.z = 0.0;  
      //move forward
      if(cmd =='w'){
        base_cmd.linear.x = 0.25;
      }
      //move backwards
      if(cmd =='s'){
        base_cmd.linear.x = -0.25;
      }
      //turn left (yaw) and drive forward at the same time
      else if(cmd =='a'){
        base_cmd.angular.z = 0.75;
        base_cmd.linear.x = 0.0;
      }
      //turn right (yaw) and drive forward at the same time
      else if(cmd =='d'){
        base_cmd.angular.z = -0.75;
        base_cmd.linear.x = 0.0;
      }
      else if(cmd =='d'){
        base_cmd.angular.z = 0.0;
        base_cmd.linear.x = 0.0;
      }
      else if(cmd == -1){
        base_cmd.angular.z = 0.0;
        base_cmd.linear.x = 0.0;
      }        
      //quit
      else if(cmd =='q'){
        base_cmd.angular.z = 0.0;
        base_cmd.linear.x = 0.0;
        break;
      }

      //publish the assembled command
      cmd_vel_pub_.publish(base_cmd);

      std::cout << "\n\r";
    }
    nocbreak(); //return terminal to "cooked" mode
    return true;
  }

};

int main(int argc, char** argv)
{
  //init the ROS node
  ros::init(argc, argv, "robot_driver");
  ros::NodeHandle n;

  RobotDriver driver(n);
  driver.driveKeyboard();
}

Of course, I wanted this code to work without having to press enter in the terminal after each command, and I also wanted the robot to stop after not receiving a new command. I used the ncurses++ library to get characters from the terminal immediately using the getch() function. To use an external library, the CMakeList file and the package file needed to be modified.

At the end of my CMakeList.txt file I added:
## Build keyboard_mover
find_package( PkgConfig REQUIRED )
pkg_check_modules( ncurses++ REQUIRED ncurses++ )
add_executable(keyboard_mover src/keyboard_mover.cpp)
target_link_libraries(keyboard_mover ${catkin_LIBRARIES})
target_link_libraries(keyboard_mover ${ncurses++_LIBRARIES})
add_dependencies(keyboard_mover ${catkin_EXPORTED_TARGETS})

And in my package.xml I added:
<build_depend>ncurses++</build_depend>

And now I am able to drive the Create around after compiling with catkin_make. Note: you may need to install the ncurses library if you don't already have it.
sudo apt-get install ncurses-*
To run this you must run the following commands in different terminal windows in the following order:
roscore
rosrun irobot_create_2_1 # you may need to chmod 666 your tty/USB0 for this to work
rosrun robot_mover keyboard_mover


Update: I upgraded to ROS Indigo, and to get catkin_make to work again, I had to modify the CMakeLists.txt as follows:
## Build keyboard_mover
find_package( PkgConfig REQUIRED )
pkg_check_modules( ncurses++ REQUIRED ncurses++ )
add_executable(keyboard_mover src/keyboard_mover.cpp)
target_link_libraries(keyboard_mover ${catkin_LIBRARIES} ncurses)
target_link_libraries(keyboard_mover ${ncurses++_LIBRARIES})
add_dependencies(keyboard_mover ${catkin_EXPORTED_TARGETS} keyboard_mover)