ros_baxter_workshop

This repository contains information for getting started with ROS and Baxter robot. This repository assumes that you have a working Ubuntu OS.

Prerequisites

• Ubuntu 14.04 LTS

ROS Indigo and Baxter API Installation

• ROS Indigo can be installed by following the official wiki page here. However, the Baxter API website contains the same procedure. Therefore, users can follow the Baxter API website, as mentioned in the next point.
• The Baxter API website is here.

Installations of Python packages using pip

pip is the package installer for Python. Below are the steps to install pip, ipython, and jupyter-

sudo apt install python-pip
sudo pip install --upgrade pip
sudo pip install --upgrade ipython
sudo pip install --upgrade jupyter

Basics of Python required for ROS

Minimal introduction to Python (version 2.7).

Defining a variable

i = 0
name = "Ravi"
price = 1.5
correct = True

Loops

# repeat print statement 10 times or print 10 numbers starting from 0
for i in range(10):
    print i

List

A list is a powerful container to store various objects.

fruits = ["apple", "mango", "orange"]
fruits.append("grape")

A minimal introduction is presented above. Users are strongly advised to read further!

Creating a ROS Package

Use catkin_create_pkg command to create a ROS package.

cd ros_ws/src
catkin_create_pkg hello_ros rospy roscpp

Please follow the official ROS wiki page for future study here.

Creating ROS Publisher and Subscriber in Python

Publishers and subscribers are the backbones of the ROS framework. In the following subsections, we will create a publisher and subscriber for string datatype.

Creating a ROS Publisher

import rospy
from std_msgs.msg import String

def publisher():
    pub = rospy.Publisher("my_ros_topic", String, queue_size=10)
    rospy.init_node("publisher")
    rate = rospy.Rate(10) # 10hz
    index = 0 
    while not rospy.is_shutdown():
        hello_str = "hello world %d" % index
        print hello_str
        pub.publish(hello_str)
        rate.sleep()
        index += 1

if __name__ == "__main__":
    try:
        publisher()
    except rospy.ROSInterruptException:
        pass

Creating a ROS Subscriber

import rospy
from std_msgs.msg import String

def callback(data):
    print data
    
def listener():
    rospy.init_node("listener")
    rospy.Subscriber("my_ros_topic", String, callback)
    rospy.spin()

if __name__ == "__main__":
    listener()

Please follow the official ROS wiki page for future study here.