A Platform for Local Interactions between Robots in Large Formations

flybittencobwebAI and Robotics

Nov 2, 2013 (3 years and 1 month ago)

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A Platform for Local
Interactions between Robots
in Large Formations

Ross Mead

Jerry B. Weinberg

Jeffrey R. Croxell


A Platform for Local Interactions between

Robots in Large Formations

Problem

swarm

formation


A Platform for Local Interactions between

Robots in Large Formations

Background


Fredslund & Mataric 2002




Balch & Arkin 1998


Reynolds 1987




Farritor & Goddard 2004


A Platform for Local Interactions between

Robots in Large Formations

Formation Control


Utilize
reactive

robot control strategies


closely couple sensor input to actions



Treat the formation as a
cellular automaton


lattice of computational units (
cells
)


each cell is in one of a given set of states


governed by a set of rules


A Platform for Local Interactions between

Robots in Large Formations


A desired formation,
F
, is defined as a
geometric description…


i.e., mathematical function


F

← y = ax
2
, where
a

is some constant

Formation Control

F

← y = ax
2


A Platform for Local Interactions between

Robots in Large Formations


A robot is chosen as the
seed
, or starting
point, of the formation.

Formation Control

F

← y = ax
2

seed


A Platform for Local Interactions between

Robots in Large Formations

Formation Control


The desired location on the formation is determined by
calculating a relationship vector from
c,



where
c

is the formation
-
relative position (
x
i
,
y
i
) of the robot,


… and the intersection of the function
F

and a circle
centered at
c

with radius
r
, where
r

is the distance to
maintain between neighbors in the formation.

c

← (
x
i
,
y
i
)

r
2

← (x
-
c
x
)
2

+ (y
-
c
y
)
2

F

← y = ax
2

r

r

seed


A Platform for Local Interactions between

Robots in Large Formations


Relationships and states are communicated locally to
robots in the seed’s neighborhood, which propagates
changes in each robot’s neighborhood in succession.


Using sensor readings, robots attempt to acquire and
maintain the calculated relationship with their neighbors.

Formation Control

c

← (
x
i
,
y
i
)

r
2

← (x
-
c
x
)
2

+ (y
-
c
y
)
2

F

← y = ax
2

r

r

seed


A Platform for Local Interactions between

Robots in Large Formations

c

← (
x
i
,
y
i
)

r
2

← (x
-
c
x
)
2

+ (y
-
c
y
)
2


Despite only local communication, the calculated
relationships between neighbors results in the
overall organization of the desired global
structure.

Formation Control

F

← y = ax
2

seed


A Platform for Local Interactions between

Robots in Large Formations


Thus, it follows that a movement command sent
to a single robot would cause a chain reaction in
neighboring robots, which then change states
accordingly, resulting in a global transformation.

Formation Control

seed


A Platform for Local Interactions between

Robots in Large Formations

Formation Control


A Platform for Local Interactions between

Robots in Large Formations

Formation Control


Likewise, to change a formation, a seed
robot is simply given the new geometric
description, and the process is repeated.

F

← y = 0

seed


A Platform for Local Interactions between

Robots in Large Formations

Robot Platform


Each robot features:


a
Scooterbot II

base


differential steering system


an
XBC v2

microcontroller


executes formation control algorithm


a color
-
coding system and color camera


visual identification and tracking of neighbors


an
XBee

radio communication module


sharing information within a robot’s neighborhood


A Platform for Local Interactions between

Robots in Large Formations

Robot Platform



Scooterbot II

base


precision cut double
-
decker base


rigid expanded PVC


strong, but very light


2" risers for additional decks


differential steering system


http://www.budgetrobotics.com/


A Platform for Local Interactions between

Robots in Large Formations

Robot Platform



XBC v2

microcontroller


executes formation algorithm


back
-
EMF PID motor control


fast charging


~1 hour to fully charge


http://www.botball.org/


A Platform for Local Interactions between

Robots in Large Formations

Robot Platform



Color
-
coding system


visual identification and
tracking of neighbors




Color camera


multi
-
color, multi
-
blob
simultaneous color tracking

Start
y

Stop
y

ID
y

Start
y

-

ID
y

ID
y

-

Stop
y

Start
y

Stop
y

Start
y

-

Stop
y

Robot
ID

= ID
max

* (Start
y

-

ID
y
) / (Start
y

-

Stop
y
)


A Platform for Local Interactions between

Robots in Large Formations

Robot Platform


XBee

radio communication module


sharing state information within a robot’s neighborhood


ZigBee/IEEE 802.15.4

specification


up to 65,535 nodes on a network


support for multiple network topologies


low duty cycle


long battery life


collision avoidance


retries and acknowledgements


link quality indication


128
-
bit AES encryption


http://www.maxstream.net/


A Platform for Local Interactions between

Robots in Large Formations

References


Balch, T. & Arkin R. 1998. “Behavior
-
based Formation Control for Multi
-
robot Teams” IEEE Transactions on
Robotics and Automation, 14(6), pp.
926
-
939.



Bekey G., Bekey, I., Criswell D.,
Friedman G., Greenwood D., Miller D.,
& Will P. 2000. “Final Report of the
NSF
-
NASA Workshop on Autonomous
Construction and Manufacturing for
Space Electrical Power Systems”, 4
-
7
April, Arlington, Virginia.



Farritor, S.M., & Goddard, S. 2004.
“Intelligent Highway Safety Markers”,
IEEE Intelligent Systems, 19(6), pp. 8
-
11.


Fredslund J., & Mataric, M.J. 2002.
“Robots in Formation Using Local
Information”, The 7th International
Conference on Intelligent Autonomous
Systems, Marina del Rey, California.



Reynolds, C.W. 1987. “Flocks, Herds,
and Schools: A Distributed Behavioral
Model, in Computer Graphics”, 21(4)
SIGGRAPH ’87 Conference
Proceedings, pages 25
-
34.



Tejada S., Cristina A., Goodwyne P.,
Normand E., O’Hara R., & Tarapore,
S. 2003. “Virtual Synergy: A Human
-
Robot Interface for Urban Search and
Rescue”. In the Proceedings of the
AAAI 2003 Robot Competition,
Acapulco, Mexico.


Questions?

For more information,

visit the
exhibition

or

http://roboti.cs.siue.edu/projects/formations/