ROS Multinode Control

Exemplary code Autonomous Robotics Lab

@ Celi Sun @ Nov, 2017 @ Brandeis University

This is a practice to write multiple nodes communicating using the three major ROS functions: topic, action and service, to complete a simple task of asking-turtlebot-to-spin. The three nodes nlp_server, console_reader and motor_action_server are collaborating via the main, by reading the human user's inputs on condole, prcessing the reading and manipulating the turtlebot (to do the spinning to a certain degree) accordinly.

Nodes:

• main: the main coordinator, listens to console reader for user input, can invoke NLP service for input processing, and can send goals to action server for turtlebot mission
• console_reader: read inputs from the user and publish through message to the Main node
• nlp_server: a simple NLP service node to take a string as input when invoked by the Main, e.g. "turn 361" and return an float e.g. "-1"
• motor_action_server: publish action mission to turtlebot about motor action to take, e.g. spin -90 degrees, and print out the feedback during the mission, such as the time consumed and angles left

The strcuture of communication between nodes can be described as below:

 

Dependencies

• ros kinetics
• python

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Run this solution on your labtop

You can clone this repository from git to your own workspace by:

$ cd ~/catkin_ws/src
$ git clone https://github.com/campusrover/CourseExemplary_RosConsoleController.git

Go back to catkin_ws and build the packages in the workspace by running catkin_make command:

$ cd ..
$ catkin_make

Now you can run the solution by launch file:

$ roslaunch CourseExemplary_RosConsoleController bringup.launch

If launched successfully, you will see the line "What do you want the robot to do?",

now type in command to activate the console reader. For example:

What do you want the robot to do?
$ turn 90

Now just sit tight and watch the turtlebot while getting feedbacks during the action!