Transcript here - Tufts University

Team Spot
Cooperative Light Finding Robots
A Robotics Academy Project
Louise Flannery, Laurel Hesch,
Emily Mower, and Adeline Sutphen
Under the direction of:
Professor Chris Rogers
Tufts University , Fall 2003
Team Spot: Motivation
The Robotable
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The Robotable combines virtual and real world objects, allowing
users to communicate and manipulate each other’s robots in a
real time environment.
A table similar Tufts Robotable is in development at Lincoln
University in Christchurch, New Zealand.
Team Spot
Project Goal
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Develop a team of mobile autonomous robots
that, within the boundary of the Robotable, will
locate and travel to a spot of bright light.
To relate the project to children through
education outreach through the CEEO and
Tufts Department of Child Development.
Design Constraints
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The robots must be autonomous
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The robots must fit onto the Robotable
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No central processing unit.
Must be small enough to maneuver around the table.
The stationary robots must determine the
position of the light and verify it using a mobile
robot and to report that position to the user.
Design Idea: Triangulation
M
St.
St.
3 Robots (2 Stationary, 1 Mobile)
 The two stationary robots will scan 90 degrees and determine the position
within the scan at which the the greatest light intensity was found.
 They will send this position to the mobile robot
 The mobile robot uses this position to determine its movement pattern.
 The mobile robot then travels to the identified location.
Design Idea: Sliding Arms
M
Y
A
R
M
ARM
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X
3 Robots (2 Robotic Arms, 1 Mobile Robot)
Robotic Arms start at (0,0) and advance out, along their specific sides- the x
and y axis of the RoboTable.
The arms locate the x and y coordinates with the greatest light intensity and
send the information to the mobile robot.
When the mobile robot has found the light spot, it reports its coordinates.
Design Idea: Quadrant System
M
1
M
2
Li
gh
t
Sp
ot
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4
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4 Mobile Robot System
The Mobile robots will determine which quadrant has the light spot.
This quadrant will be subdivided into 4 quadrants.
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M
3
The within the specified quadrant mobile robot will move to the corner of its new subquadrant and determine which sub-quadrant holds the light spot.
The other robots will move to positions on the edge of their quadrants closest to the spot of
light
The mobile robots will repeat this process until one converges on the light
spot.
Once again, upon completion the mobile robot will report its coordinates.
Prototype: The Spot Finder
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Lego prototype.
Triangulation method
RCX IR communication
Successes
 Found the position of the light
using triangulation.
 Developed programming
methods for combining and
processing data between
multiple robots
Areas of Improvement
 Need for more sturdy
robots.
 Limited range with IR
communication
 Lego rotation sensor
unreliable for find the
position of the light.
Prototypes: Lego Robots
Original Mobile Robot
Original Stationary Robot
Flow Chart of Functionality
Stationary robots scan for
brightest light position.
Mobile robot reads
in light value
The position of the
greatest spot is
transmitted via IR to
the mobile robot.
Interprets value
using a lookup table
Mobile Robot moves
to correct position
Electrical Components
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There are three main electrical modules:
Infrared Communication
 Motor Control
 Light Sensing
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These three modules were coordinated using the
OOPic-R Microprocessor.
OOPic-R Microprocessor
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This microprocessor uses object oriented
programming in Basic, which simplifies the
programming process.
The chip includes 31 I/O pins and additional
voltage sources for device interface.
The microprocessor’s voltage source was used
for IR communication, the Liquid Crystal
Display (LCD), and the photo-resistor circuits.
Light Sensing
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A simple photo-resistor was placed in series with
a resistor to register values of light.
This was inputted to the microprocessor using
the analog to digital converter
This module’s accuracy is hampered by ambient
light spots that are brighter than the light being
sought.
IR Communication
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While infrared communication is currently functional, it
is inaccurate over long distances.
High speed serial communications functionality was
abandoned due to a high degree of inaccuracy.
Currently, the stationary robots send infrared pulses
corresponding to the position of brightest light.
The Mobile Robot interprets the number of pulses sent
to determine the stationary robot position.
This was the most problematic module in this project.
Motor Control
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The microprocessor controls the servo motors
for both the mobile and stationary robots.
The servos have highly variable torque, which
makes the mobile robot veer to one side and the
stationary robots have slightly variant positional
rotation.
The motion is calculated looking a look-up table
using the IR received value as inputs.
Motor Controller:
Look-Up Table
Mobile Robot
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Powered by 2 Servo
Motors
Controlled with the
OOPIC-R
microcontroller
IR receiver
Liquid Crystal Display
Stationary Robot
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Light sensor rotates atop
a DC servo motor
Controlled by OOPIC-R
microcontroller
IR transmitters
Team Spot In Action
Team Spot in Action
Team Spot Webpage
Child Development Objectives
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Learn about the engineering process and the science and
technology content of each Team’s robotics challenge.
Help engineers think about how to communicate and adapt their
knowledge for peers without their engineering background and
for children.
Synthesize and adapt main concepts from team projects
appropriately for a 4th-6th grade robotics curriculum.
Implement this curriculum as an after-school enrichment
program in Spring 2004.
Evaluate the process of making complex technology accessible
to children.
Course Structure
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Day of Introduction
3 Main Phases:
Mobile robots
Stationary robots
Integrative final project-Treasure Island
Analysis of curriculum
Team Spot: The Future
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IR will be replaced with blue tooth technology.
Implementation of the multiple spot and
moving spot problems.
Development of more accurate methods of
scanning through 90-degrees (stationary robot).
Development of method for altering the
inequality of the mobile robot servo motors.
CEEO after-school workshops in Spring 2004.