Autonomous Wheelchair

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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

1. General Project Overview
2. Overview of Interaction with the Wheelchair
3. Testing and Results
4. Final Thoughts
5. Tutorial Walk-Throughs

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Outline

1. General Project Overview
2. Overview of Interaction with the Wheelchair
3. Testing and Results
4. Final Thoughts
5. Tutorial Walk-Throughs

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Project

• 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

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Working with the Wheelchair

• First semester with research assistants
• Objective was to determine optimal parameter
  lists
• Majority of work done through wireless connection
  between wheelchair and PC

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Wireless Networking
Home Wireless Network
Wheelchair Wireless Network
http//tradelinecom.com/images/WirelessHomeNetwork
.jpg
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Testing Environment
Clapp 201 - Lab
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Testing Environment
Clapp 201 - Lab
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Testing Environment
Clapp 201 - Lab
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Testing Environment
Clapp Hallway
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Testing Environment
Clapp Hallway - Doors
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Testing Environment
Kendade Bridge - Doors
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Testing Environment
Kendade Bridge
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Testing Environment
Kendade Bridge
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Testing Environment
Kendade Atrium
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Testing Environment
Kendade Atrium
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Testing Environment
Kendade Atrium
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Laser Sensors
http//www.philohome.com/sensors/lasersensor.htm

• Laser sensors use light beams to measure distance
• The way the light returns to the sensor is used
  to calculate the distance

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Sensors
Upper Sensor

• Three laser sensors
• One high, two low
• Scan on horizontal plane
• Laser sensors are used for localization and path
  planning
• Bump sensors in case laser sensors fail

Touch Screen
Lower Back Sensor
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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
Smart Drive Mode
Express Drive Mode
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Drive Modes - Manual
Express Drive Mode
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Drive Modes - Smart
Manual Drive Mode
Express Drive Mode
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Drive Modes - Express
Manual Drive Mode
Smart Drive Mode
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Drive Modes - Express
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Express Drive Mode in Action
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Goal Drive Mode and MobileEyes
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Goal Drive Mode and MobileEyes
Wheelchair
Path
Goal
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Goal Drive Mode and MobileEyes
Person
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Outline

1. General Project Overview
2. Overview of Interaction with the Wheelchair
3. Testing and Results
4. Final Thoughts
5. Tutorial Walk-Throughs

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3 Levels of Interaction

• Basic User Tasks
• Intermediate User Tasks
• Advanced User Tasks

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Basic User Tasks - Patient

• 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

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Definition

• GUI Graphical User Interface

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GUI

• The touch screen interface on the chair
• Will be able to
• support other
• devices at later
• date

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Start Up, Shut Down, Recharge

• Begin from the back of the chair
• Begin from the screen
• Begin by unplugging

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Move By Pushing

• Just in case something goes wrong
• Motors disengaged
• Lever in back
• Patient may need to be able to tell someone how

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 Re-enable the Motors After Emergency Stop

• Two emergency stop buttons
• Immediately apply brakes and disable motors
• Push the rectangular red button to get the motors
  back
• Once for joystick
• Twice to return to normal

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 Intermediate User Tasks-Doctor/Therapist

• 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 Chairs
  Interface

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What is X-Windows?

• A way to display the touch screen graphics on a
  remote computer

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Connect With X-Windows

• Useful to be able to control the chair remotely
  as if in chair
• Ex For choosing goals

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What is MobileEyes?

• The main way to handle the chair remotely
• The place to make maps, change goals, and change
  parameters

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Connect to the Chair Open MobileEyes

• Connecting remotely
• Change your IP address
• Connect to the network
• Opening MobileEyes
• Username and password
• unnecessary
• Set the Robot Server

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Localization

• Like using a map and compass once youve found
  where you are and what direction youre facing,
  youre not lost

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Using MobileEyes to Localize and to Drive

• Localizing
• 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

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Change Maps in MobileEyes Enable/ Disable Goals
On Chair

• Need to open both Map and
• LaserLocalizationMap to
• change maps
• To enable/disable goals
• Go to Look Feel, then Goal List
• on wheelchair
• (Or X-Windows)
• Choose goals from list

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 Chair Guru Tasks - Administrator/Developer

• How to Create a New Map
• How to Create a New Goal on the Map
• How to Change Parameters

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Create a New Map

• Drive the chair around so the upper sensor can
  create the map
• With MobileEyes open

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Edit Map andCreate New Goals

• Clean up the new map
• Using tools in Mapper3
• Add new goals in Mapper3
• Save map to Chair

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Change Parameters in MobileEyes

• Go to Tools, then RobotConfig
• Parameters allow you to change things like the
  speed of the chair and the size of the padding

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Outline

1. General Project Overview
2. Overview of Interaction with the Wheelchair
3. Testing and Results
4. Final Thoughts
5. Tutorial Walk-Throughs

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• Parameters
• Observations

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User Level
Level 1 Patients
Level 2 Physicians
Level 3 Developer
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User Level
User Level
Level 1 Patients
Level 2 Physicians
Level 3 Developer
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Important Questions

1. What are parameters?
2. How to modify the parameters of the wheelchair?
3. What parameters to modify?

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Parameters

• Are variables. (There might be restrictions)
• Way of communication between user and
• computer .
• Impacts the behavior of any computer
• system.

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Parameter Analogy
No English!
No Barks!
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Parameter Analogy
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Parameter Analogy
Parameter val1
Computer shows behavior1
Parameter
User
Computer shows behavior2
Parameter val2
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• How To Modify Parameters????

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MobileEyes

• Used to change parameters.
• Records values in mm sec.

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To Access Higher Parameters

• Set Parameter Priority to Expert

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• BUT What Parameters to Modify????

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Main Concerns

• Quite fast.
• Starts and ends with a jerk.
• Turning not smooth.
• Does not go through doorways.
• Almost runs into obstacles,
• before stopping.

Work with speed/velocity parameters
Perhaps parameters for acceleration?
Perhaps parameters for rotation?
Padding parameters
Padding parameters
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Parameter Lists

• Each Drive Mode ? different set of parameters
• Same name ? similar function ? slightly different
  implementation.

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Parameter list Express Drive

• Robot Config - a short list speed related.
• Path Planning Setting - full list for Express
  Drive.

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Parameter list - Smart Drive

• TeleOp Settings - full list for Smart Drive.

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List of Modified Parameters

• MaxVel
• TransAccel
• TransDecel
• SideClearanceAtSlowSpeed
• FrontPaddingAtSlowSpeed
• FrontPaddingAtFastSpeed
• ForwardSideClearanceAtSlowSpeed

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Procedural Standards

• Test trials 6 to 15 trials.
• Distance of 6069mm (6m).
• When testing each parameter
• simulated a hospital setting.
• patients point of view.

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Procedural Standards
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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.
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TransAccel

• Increasing value, decreases time to reach maximum
  speed.
• In ExpressMode
• TransAccel 425
• Lower value ? jerkier start.

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TransDecel

• Slows down .
• Stopping distance 1.5m.
• In Express Mode
• TransDecel 175
• If TransDecel lt 175
• stops smoothly BUT
• overshoots goal.

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TransDecelOvershooting the Goal
End Goal
Starting Goal
Wall
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TransDecel Caution!!!!
Do NOT change the value of this parameter!!!!!
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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.

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Front Padding

• Determines how close an object can approach.
• In Express Drive
• FrontPaddingAtSlowSpeed 300
• Applies when speed lt MaxVel.
• FrontPaddingAtFastSpeed 500
• Applies when speed MaxVel.

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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???
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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.

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Outline

1. General Project Overview
2. Overview of Interaction with the Wheelchair
3. Testing and Results
4. Final Thoughts
5. Tutorial Walk-Throughs

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Blind Spots
upper laser, 1.7 m
bottom lasers, 13 cm
floor, 0 cm
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Blind Spots
http//www.yankodesign.com/images/design_news/2008
/04/11/music_table.jpg
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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

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Cautions

• Difficulty starting too close to an obstacle
• Inability to see black objects

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When Express Drive Mode Goes Wrong
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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
• Continued exchange between the research group and
  Spaulding
• Further documentation needs to be developed

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Thank You!
A special thank you to Dr. Dan Barry, Dr.
William Kennedy, and MobileRobots
Questions?
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Outline

1. General Project Overview
2. Overview of Interaction with the Wheelchair
3. Testing and Results
4. Tutorial Walk-Throughs