Transcript Formal Approaches to Swarm Technologies GSFC Executive Briefing

GSFC
Formal Approaches
to Swarm Technologies
Executive Briefing
Christopher Rouff, Amy Vanderbilt - SAIC
Walt Truszkowski, James Rash - NASA GSFC, Code 588
Mike Hinchey - NASA GSFC, Code 581
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Problem
 Future space missions will require cooperation
between multiple satellites/rovers
 Developers are proposing intelligent,
autonomous swarms to do new science
 Swarm-based systems are highly parallel and
nondeterministic
 Testing these systems using current techniques
will be difficult to impossible
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ANTS Mission
ANTS: Mission Concept 2020
2. Self propelled transit
Asteroid belt
1. Assembly & release
3. Long-Range Operations
Rulers
Asteroid(s)
Workers
Messengers
Workers
Workers
4. Swarm (Fly by) Operations
X-Ray Worker
Messenger
MAG Worker
IR Worker
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Lagrange Point Habitat
Earth
6. A messenger carries
findings to Earth
when needed.
5. Repeat steps 3 and 4.
M. L. Rilee, EIT, S. A. Curtis, NASA/GSFC, 2001 .
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ANTS MISSION
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Difficulty of Testing Swarms
 Emergent properties that may not be known
 Highly distributed and parallel
 Large number of interacting entities
 Worse than exponential growth in interactions
 Intelligent entities (capabilities increase over time)
 Total or near total autonomy
 Very little experience in verification and validation of
swarm-based systems
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Relevance to NASA
 Many future missions will be intelligent
collaborative distributed systems
 Autonomy and autonomic properties will be
necessary to manage and operate these systems
 Swarms will allow new way for doing science
 Verifying these missions will be paramount due
to complexity and emergent behaviors
 Need verification techniques for these systems
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Approach
 Survey formal approaches for agent-based, multi-
agent and swarm-based systems for appropriate
swarm-based methods
 Apply most promising approaches to parts of ANTS
 Evaluate methods for needed properties
 Model and outline swarm-based formal method
 Develop formal method for swarm-based systems
 Do formal specification of ANTS using new method
 Prototype support tools
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Accomplishments
 Surveyed formal approaches
 Applied most promising approaches to ANTS
 Evaluated methods
 Developed properties for swarm formal method
 Developed model and outline for a hybrid
swarm-based formal method
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Model of Formal Method
Swarm Formal Method Model and Outline
LEADER _ COM i ,conv  leader .in ? msg 
SendMessage, Re ceiveMessa ge,


Re ason, Pr ocess

case LEADER_MES SAGEi ,conv,msg
if sender (msg) = LEADER
MESSENGER_MESSAGEi ,conv,msg
if sender (msg) = ME SSENGER
WORKER_MES SAGEi ,conv,msg
is a set of (partial) transition functions
where each transition function maps
if sender (msg) = WO RKER
EARTH_MESS AGEi ,conv,msg
Memory  Input  Output  Memory
if sender (msg) = EARTH
ERROR_MESS AGEi ,conv,msg
memory'  (Goals, Mode l , CommsTracking )
[Communicating]ReasoningDeliberatve(Leader)[Reasoning]
[Reasoning] SendMessage (Leader,Worker)[Communicating]
[Processing] SendMessage (Leader, Worker) [Communicating]
otherwise
0.5
p
SendMessageWorker
50
2
SendMessageLeader
50
2
SendMessageError
1
1
ReceiveMessageWorker
50
2
ReceiveMessageLeader
50
2
ReceiveMessageError
1
1
ReasoningDeliberatve
50
2
ReasoningReactive
50
2
ProcessingSortingAndStorage
17
2
ProcessingGeneration
17
2
ProcessingPrediction
17
2
ProcessingDiagnosis
16
2
n k  l  m k  n k  l  m k  n k  l
ProcessingRecovery
16
2
n k  m k  (n  m) k  m k  n k
ProcessingRemediation
17
2
0.5
0.25
Reasoning
0.25
0.25
1
Initial
state
Agent State
0

0
P
0

0
.5 .25 .25 

.5 .25 .25 
.5 .25 .25 

0 .5 .5 
Processing
Identity
Communicating
0.5
Communicating  50 2 : SendMessag eWorker.Communicating
 50 : SendMessag eLeader .Communicating
2
 1 1 : SendMessag eError .Communicating
 50 : ReceiveMessageWor ker.Communicating
2
 50 2 : ReceiveMessageLea der.Communicating
Reasoning
 1 : ReceiveMessageErr or.Communicating
1
 50 2 : ReasoningD eliberatve .Reasoning
 50 : ReasoningR eactive .Reasoning
2
 17 2 : Processing SortingAnd Storage . Pr oces sin g
 17 2 : Processing Generation . Pr oces sin g
 17 2 : Processing Prediction . Pr oces sin g
 16 2 : Processing Diagnosis . Pr oces sin g
 16 2 : Processing Recovery . Pr oces sin g
 17 2 : Processing Remediatio n. Pr oces sin g
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Actions leading to the agent
state
f
0.25
Communicating
Processing
8
Next steps
 Develop formal method for swarm-based systems
based on current model
 Do formal specification of ANTS using new method
 Prototype support tools
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