TURTLEBOT
ROBOTIC GUIDE
Project Description
Teach a robot to guide a person to a predefined
destination.
General requirements:
1. Use a Turtlebot as the robot
2. 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
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
• 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
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Open Source – does not necessarily mean “FUNCTIONING”
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Sources, Documentation, and Support not easily obtained
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Newest ROS distribution designed for newest Turtlebot base
(Kobuki)
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The ROS Wiki – instructions misleading
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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
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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
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Nodes are processes that perform computation
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Topics are named busses over which nodes exchange messages
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Communicate with one another via topics, services, and parameters
Nodes either subscribe or publish to relevant topics
Services handle requests and replies
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Defined by a pair of messages
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Messages are simply data structures comprising of typed fields
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ROS Parameter server is a dictionary accessible via network APIs
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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
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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’
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Subscribing node is dynamic
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If multiple messages received
simultaneously then prioritize
My Solution (Follower with Voice Commands)
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The node needs help prioritizing
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Processing and movement become slowed when subscribing to
commands from multiple nodes
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Using multiple pivot nodes helps speed and processing
Created new voice commands that correspond to OS commands
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Bringing the process down to the OS level allows for universal actions
across all applications
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The use of shell scripts allows the ability to talk to ROS via command line
OS helps flag enabled nodes
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Mobile base will then only listen for commands from enabled nodes
Command Recognition
Process 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
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Alter launch files to see how nodes react
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Adjust Node publishing target
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Shows which nodes are capable of handling certain applications or
combinations of applications
Try as much hardware as possible
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On screen messages are given when things go wrong
Different laptops, headsets, graphics cards, etc. respond and process
very differently from one another
Experiment on EVERYTHING
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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
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RESEARCH – find as much information from as many different
sources as possible
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Run it and see what happens
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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
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Make alterations and see what kind of errors come up, helps to
correlate what broke to what was changed
Project Continuation & Advice
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UNDERSTAND ROS!!!
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Follow the link trail
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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
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Not understanding how ROS is working makes it extremely difficult to try and
make any changes
Gyro is built in allowing for more efficient processing and little calibration
Attempt to break Kinect data apart
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The Kinect has many separate sensors, learning how to get data from each
sensor individually would allow for efficient visual application multitasking