TURTLEBOTROBOTIC GUIDE

Project DescriptionTeach a robot to guide a person to a predefined destination.

General requirements:1. Use a Turtlebot as the robot2. The robot must use a vision algorithm(s) as the main guidance.3. Sensors such as bump, infra-red and ultra-sound could provide direction and safety for the robot.4. First get the robot to follow someone somehow "remembering" the route so that it can take a turn leading.5. The solution should be easily modified for alternative routes.6. Check out Joseph Stawicki's 2013 project for techniques about driving the robot.

Meet Turtlebot

Microsoft Kinect

+A Laptop

+iRobot Create

Hardware Breakdown

• Kinect and Mobile Base Gyro combined so all sensor data can be read from one place

• iRobot create listens for commands on a serial port, so serial port to USB converter required for communication.

• Sensors send data to laptop, laptop sends commands to the mobile base.

• Hardware requires software framework in order to receive, process, and send data

The Robot Operating System(ROS)Services Provided by ROS:• Hardware abstraction• Low-level device control• Message passing service• Name and Parameter service• Package management +

• Laptop’s main OS is Ubuntu which is then overlaid with ROS.

• ROS also allows for Android connectivity to the robot

Developing Apps with ROS

• Workspace allows for packages to be installed and edited easily

• Very easily pulls from repositories for quick installs

• Symbolically linked to main ROS install• Workspace set up based on directory

structure

Many LanguagesOne Environment

• ROS incorporates a lot of different programming languages• C, C++, Python, Java, and more

• The catkin workspace allows for building and debugging across all languages

• ROS created ROS specific API’s for Python and C++ (rospy & roscpp)• Makes it extremely easy to call ROS

functions• Also allows for cross-language

communication

ROS Limitations and Frustrations Open Source – does not necessarily mean “FUNCTIONING”

Sources, Documentation, and Support not easily obtained

Newest ROS distribution designed for newest Turtlebot base (Kobuki)

The ROS Wiki – instructions misleading

For the first time ever, Google.com was not my friend

How it Works Remote communication to the Turtlebot required

Workstation Computer connects via SSH

Applications are also run locally on Workstation Computer for monitoring, information processing, and visuals These applications receive info via HTTP

Android connectivity via HTTP• Incorporated the Wifi

Pineapple• Allows for a portable and

private Local Area Network

Wireless Communication

Services, Nodes, Parameters, Messages, Topics Nodes are processes that perform computation

Communicate with one another via topics, services, and parameters

Topics are named busses over which nodes exchange messages Nodes either subscribe or publish to relevant topics

Services handle requests and replies Defined by a pair of messages

Messages are simply data structures comprising of typed fields

ROS Parameter server is a dictionary accessible via network APIs Nodes use this to retrieve parameters at runtime

Software & Hardware Communication

Kinect Example

Sound Demo

• Keyboard inputs command• Keyboard node processes

command• Parameters obtained from

server• Word node processes the

sound to play based on parameters

• Sound node processes sound

• Output to speakers

The Puzzle Pieces Teleoperation Room mapping (SLAM Algorithm) Autonomous Navigation of Known Map Following Voice Commands Color Blob Tracking

Its all here! But why is it in pieces?

• Applications are limited by the way they interact with the robot

• Publishing/Receiving information cannot be done on the same node at the same time

Room Mapping with the SLAM Algorithm

Autonomous Navigation of a Known Map

The Problem: Communication Interrupts Both Nodes need to publish movement

commands to the mobile base The Voice Command Node is designed to

continually publish directly to the mobile base node

The mobile base node sees the Voice Command messages as priority and blocks movement commands from the Follower node

The Pivot Node/Dynamic Subscriber Could also be considered ‘nested

nodes’

Subscribing node is dynamic

If multiple messages received simultaneously then prioritize

My Solution (Follower with Voice Commands) The node needs help prioritizing

Processing and movement become slowed when subscribing to commands from multiple nodes

Using multiple pivot nodes helps speed and processing

Created new voice commands that correspond to OS commands Bringing the process down to the OS level allows for universal actions

across all applications

The use of shell scripts allows the ability to talk to ROS via command line

OS helps flag enabled nodes Mobile base will then only listen for commands from enabled nodes

Command RecognitionProcess for enabling follow mode

• This particular command effects the follower node the most. Little is done inside the Voice Command Node.

Command Recognition

Process for disabling follow mode

• This particular command corresponds to actions in both the Voice Command Node and the Follower Node

Testing/Methodology Alter launch files to see how nodes react

On screen messages are given when things go wrong

Adjust Node publishing target Shows which nodes are capable of handling certain applications or

combinations of applications

Try as much hardware as possible Different laptops, headsets, graphics cards, etc. respond and process

very differently from one another

Experiment on EVERYTHING If I didn’t know what it was, I played with it until I understood how it

worked

Follower with Voice Commands Live Demo

Learning and Development Process RESEARCH – find as much information from as many different

sources as possible

Run it and see what happens Try everything that’s available, watch and see how the Robot reacts

and then connect what’s seen to what sources say

Guess, check, and actually read the error messages Make alterations and see what kind of errors come up, helps to

correlate what broke to what was changed

Project Continuation & Advice UNDERSTAND ROS!!!

Not understanding how ROS is working makes it extremely difficult to try and make any changes

Follow the link trail Google.com is not your friend for this project. Scimming google search

results will get you almost no where. In order to find good information follow links in forums and on web pages that indicate they might be helpful. Eventually you will find something actually useful

Consider upgrading mobile base to the Kobuki Gyro is built in allowing for more efficient processing and little calibration

Attempt to break Kinect data apart The Kinect has many separate sensors, learning how to get data from each

sensor individually would allow for efficient visual application multitasking

Q&A