Autonomous
Wheelchair
Abigail Drury '10
Rittika Shamsuddin '12
Melissa Frechette '11
Professor Audrey Lee St. John
Dr. Dan Barry
Dr. William Kennedy
14 May 2010
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Outline
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General Project
Overview
Overview of
Interaction with the
Wheelchair
Testing and Results
Final Thoughts
Tutorial WalkThroughs
Outline
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2.
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General Project
Overview
Overview of
Interaction with the
Wheelchair
Testing and Results
Final Thoughts
Tutorial WalkThroughs
Project
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Created by MobileRobots
and Dr. Dan Barry
Research team
methodically tested and
developed comprehensive
documentation
Doing our first exchange of
the the chair - the first step
to giving patients with
impaired motor function the
option for independent
mobility and privacy
Working with the
Wheelchair
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First semester with
research assistants
Objective was to
determine optimal
parameter lists
Majority of work done
through wireless
connection between
wheelchair and PC
Wireless Networking
Home
Wireless
Network
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Wheelchai
r Wireless
Network
Testing Environment
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Clapp 201 - Lab
Testing Environment
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Clapp 201 - Lab
Testing Environment
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Clapp 201 - Lab
Testing Environment
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Clapp Hallway
Testing Environment
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Clapp Hallway - Doors
Testing Environment
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Kendade Bridge - Doors
Testing Environment
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Kendade Bridge
Testing Environment
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Kendade Bridge
Testing Environment
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Kendade Atrium
Testing Environment
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Kendade Atrium
Testing Environment
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Kendade Atrium
Laser Sensors
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http://www.philohome.com/sensors/lasersensor.htm
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Laser sensors use light beams to measure
distance
The way the light returns to the sensor is used to
calculate the distance
Sensors
Upper
Sensor
 Three laser sensors
Touch Screen
Lower Back
Sensor
 One high, two low
 Scan on horizontal plane
 Laser sensors are used for
localization and path planning
 Bump sensors in case laser
sensors fail
User Interface
 Currently uses a touch
screen and
keyboard/mouse as
main I/O device.
 In future, it will also
support other
interfaces
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Drive Modes
Manual Drive
Mode
Smart Drive Mode
Express Drive Mode
Drive Modes - Manual
Manual Drive
Mode
Smart Drive Mode
Express Drive Mode
Drive Modes - Smart
Manual Drive
Mode
Smart Drive Mode
Express Drive Mode
Drive Modes - Express
Manual Drive
Mode
Smart Drive Mode
Express Drive Mode
Drive Modes - Express
Express Drive Mode in
Action
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Goal Drive Mode and
MobileEyes
Goal Drive Mode and
MobileEyes
Wheelchair
Path
Goal
Goal Drive Mode and
MobileEyes
Person
Outline
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General Project
Overview
Overview of
Interaction with the
Wheelchair
Testing and Results
Final Thoughts
Tutorial WalkThroughs
3 Levels of Interaction
 Basic User Tasks
 Intermediate User Tasks
 Advanced User Tasks
Basic User Tasks Patient
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How to Use the GUI
How to Start Up the Chair
How to Shut Down the Chair
How to Recharge the Chair
How to Move the Chair By Pushing
How to Re-enable the Motors After E-Stop
Definition
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GUI = Graphical User Interface
GUI
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The touch screen interface on the chair
Will be able to
support other
devices at later
date
Start Up, Shut Down,
Recharge
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Begin from the back of the chair
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Begin from the screen
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Begin by unplugging
Move By Pushing
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Just in case something goes wrong
Motors disengaged
Lever in back
Patient may need to be able to tell someone how
Re-enable the Motors
After Emergency Stop
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Two emergency stop buttons
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Immediately apply brakes and disable motors
Push the rectangular red button to get the motors
back
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Once for joystick
Twice to return to normal
Intermediate User
Tasks-Doctor/Therapist
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How to Use X-Windows
How to Connect to the Wheelchair from a PC
How to Open MobileEyes
How to Localize the Robot
How to Drive the Robot From MobileEyes
How to Change Maps in MobileEyes
How to Enable/Disable Goals on the Chair’s
Interface
What is X-Windows?
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A way to display the touch screen graphics on a
remote computer
Connect With
X-Windows
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Useful to be able to control the chair remotely as if
in chair
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Ex: For choosing goals
What is MobileEyes?
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The main way to handle the chair remotely
The place to make maps, change goals, and
change parameters
Connect to the Chair &
Open MobileEyes
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Connecting remotely
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Change your IP address
Connect to the network
Opening MobileEyes
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Username and password
unnecessary
Set the Robot Server
Localization
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Like using a map and compass – once
you’ve found where you are and what
direction you’re facing, you’re not lost
Using MobileEyes to
Localize and to Drive
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Localizing
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Drag robot to correct spot on map and check
localization score
Repeat as necessary
Buttons on top menu
bar for Manual and
Safe Drive
Goal list at bottom left
Change Maps in MobileEyes &
Enable/ Disable Goals On Chair

Need to open both Map and
LaserLocalizationMap to
change maps
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To enable/disable goals
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Go to Look & Feel, then Goal List
on wheelchair
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(Or X-Windows)
Choose goals from list
Chair Guru Tasks Administrator/Developer
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How to Create a New Map
How to Create a New Goal on the Map
How to Change Parameters
Create a New Map
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Drive the chair around so the upper sensor can
create the map
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With MobileEyes open
Edit Map and
Create New Goals
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Clean up the new map
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Using tools in Mapper3
Add new goals in Mapper3
Save map to Chair
Change Parameters in
MobileEyes
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Go to Tools, then RobotConfig
Parameters allow you to change things like the
speed of the chair and the size of the padding
Outline
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2.
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3.
4.
5.
General Project
Overview
Overview of
Interaction with the
Wheelchair
Testing and Results
Final Thoughts
Tutorial WalkThroughs
Parameters
&
Observations
User Level
Level 1:
Patients
Level 2:
Physicians
Level 3:
Developer
User Level
Level 1: Patients
Level 2: Physicians
Level 3: Developer
Important Questions
1. What are parameters?
2. How to modify the parameters of the
wheelchair?
3. What parameters to modify?
Parameters
Are variables. (*There might be
restrictions)
Way of communication between user and
computer .
Impacts the behavior of any computer
system.
Parameter Analogy
No English!
No Barks!
Parameter Analogy
Parameter Analogy
Parameter = val1
Computer shows
behavior1
Parameter
User
Parameter = val2
Computer shows
behavior2
How To Modify
Parameters????
MobileEyes…
 Used to change
parameters.
 Records values
in mm & sec.
To Access Higher
Parameters…
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Set Parameter Priority to Expert
BUT What Parameters
to Modify????
Main Concerns
 Quite fast.
Work with speed/velocity parameters
 Starts and ends with a jerk.
 Turning not smooth.
Perhaps parameters for acceleration?
Perhaps parameters for rotation?
 Does not go through doorways.
Padding parameters
 Almost runs into obstacles,
before stopping.
Padding parameters
Parameter Lists
 Each Drive Mode  different set of parameters
 Same name  similar function  slightly different
implementation.
Parameter list –
Express Drive
 Robot Config - a short list; speed related.
 Path Planning Setting - full list for Express Drive.
Parameter list - Smart
Drive
 TeleOp Settings - full list for Smart Drive.
List of Modified
Parameters
MaxVel
TransAccel
TransDecel
SideClearanceAtSlowSpeed
FrontPaddingAtSlowSpeed
FrontPaddingAtFastSpeed
ForwardSideClearanceAtSlowSpeed
Procedural Standards
 Test trials: 6 to 15 trials.
 Distance of 6069mm (~6m).
 When testing each parameter:
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simulated a hospital setting.
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patient’s point of view.
Procedural Standards
MaxVel
 Directly controls the speed.
 In Express Drive:
MaxVel = 600
On average  8.3sec.

In Smart Drive:
MaxVel = 900
On average  8.6sec .
Over a distance
of ~6m.
TransAccel
 Increasing value, decreases time to reach
maximum speed.
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In ExpressMode:
TransAccel = 425
 Lower value  jerkier start.
TransDecel
 Slows down .
 Stopping distance = 1.5m.

In Express Mode:
TransDecel = 175
 If TransDecel < 175 :
 stops smoothly BUT
 overshoots goal.
TransDecel
Overshooting the Goal
Starting
Goal
End
Goal
Wall
TransDecel
Caution!!!!
Do NOT change the value of this
parameter!!!!!
Side Padding
 Determines how close an object can approach.

In Express Drive:
SideClearanceAtSlowSpeed = 50

In Smart Drive:
ForwardSideClearanceAtSlowSpeed = 25
 Values allow to go through doorways.
Front Padding
 Determines how close an object can approach.

In Express Drive:
FrontPaddingAtSlowSpeed = 300
 Applies when speed < MaxVel.
FrontPaddingAtFastSpeed = 500
 Applies when speed = MaxVel.
Challenges
 Overcoming the fear of making changes.
 Could not figure out a way to measure the effect
of RotVelMax.
 Parameters with similar names.
 Battery Life.
FIRE???
Results
 Starting and ending smoother.
 Speed comfortable.
 Can go through doorways (33.5 inches wide).
 Stops at a safe distance.
 Turning is smoother but still slightly jerky.
Outline
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2.
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decompressor
are needed to see this picture.
3.
4.
5.
General Project
Overview
Overview of
Interaction with the
Wheelchair
Testing and Results
Final Thoughts
Tutorial WalkThroughs
Blind Spots
upper laser, 1.7 m
bottom lasers, 13 cm
floor, 0 cm
Blind Spots
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Final Observations
 Chair cannot see:
 Objects shorter than 13 cm
 Objects only present between 13 cm
and 1.7 m
 Hardware-based issue
 Side padding can be a little scary for
pedestrians
 Can be solved in future through
software
Cautions
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Difficulty starting too
close to an obstacle
Inability to see black
objects
When Express Drive
Mode Goes Wrong
Conclusions and
Future Work
 On our way to giving patients with cerebral palsy
the option for independent mobility and privacy
 Wheelchair is in good shape,
but needs work to improve
safety
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 Continued exchange between the
research group and Spaulding
 Further documentation needs
to be developed
Thank You!
A special thank you to Dr. Dan Barry,
Dr. William Kennedy, and MobileRobots
Questions?
Outline
1.
2.
QuickTime™ and a
decompressor
are needed to see this picture.
3.
4.
General Project
Overview
Overview of
Interaction with the
Wheelchair
Testing and Results
Tutorial WalkThroughs