self‐organising sensors for wide area surveillance using the max‐sum algorithm
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Self‐Organising Sensors for Wide Area Surveillance using the Max‐Sum Algorithm. Alex Rogers and Nick Jennings School of Electronics and Computer Science University of Southampton [email protected] Alessandro Farinelli Department of Computer Science University of Verona Verona, Italy - PowerPoint PPT PresentationTRANSCRIPT
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Self Organising Sensors for ‐Wide Area Surveillance using the
Max Sum Algorithm‐
Alex Rogers and Nick JenningsSchool of Electronics and Computer Science
University of [email protected]
Alessandro FarinelliDepartment of Computer Science
University of VeronaVerona, Italy
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Overview
• Self-Organisation– Landscape of Decentralised Coordination
Algorithms• Local Message Passing Algorithms
– Max-sum algorithm– Graph Colouring
• Wide Area Surveillance Scenario• Future Work
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Self-Organisation
Sensors
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Self-Organisation
Agents
• Multiple conflicting goals and objectives• Discrete set of possible actions
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Self-Organisation
Agents
• Multiple conflicting goals and objectives• Discrete set of possible actions• Some locality of interaction
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Self-Organisation
Agents
Maximise Social Welfare:• Multiple conflicting goals and objectives• Discrete set of possible actions• Some locality of interaction
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Self-Organisation
Agents
Central point of controlDecentralised self-organisation through local computation and message passing.• Speed of convergence, guarantees of optimality,
communication overhead, computability
No direct communication Solution scales poorly Central point of failure Who is the centre?
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Landscape of Algorithms
Complete Algorithms
DPOPOptAPOADOPT
Communication Cost
Optimality
Iterative Algorithms
Best Response (BR)Distributed Stochastic
Algorithm (DSA) Fictitious Play (FP)
Message Passing
Algorithms
Sum-ProductAlgorithm
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Max-Sum Algorithm
Variable nodes
Function nodes
Factor Graph
A simple transformation:
allows us to use the same algorithms to maximise social welfare:
Find approximate solutions to global optimisation through local computation and message passing:
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Graph Colouring
Agentfunction / utility
variable / state
Graph Colouring Problem Equivalent Factor Graph
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Graph Colouring
Equivalent Factor GraphUtility Function
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Graph Colouring
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Graph Colouring
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Optimality
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Communication Cost
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Robustness to Message Loss
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Wide Area Surveillance Scenario
Dense deployment of sensors to detect pedestrian and vehicle activity within an urban environment.
Unattended Ground Sensor
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Energy Constrained Sensors
Maximise event detection whilst using energy constrained sensors:– Use sense/sleep duty cycles
to maximise network lifetime of maintain energy neutral operation.
– Coordinate sensors with overlapping sensing fields.
time
duty cycle
time
duty cycle
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Self-Organising Sensor Network
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Energy-Aware Sensor Networks
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Future Work• Continuous action spaces
– Max-sum calculations are not limited to discrete action space
– Can we perform the standard max-sum operators on continuous functions in a computationally efficient manner?
• Bounded Solutions– Max-sum is optimal on tree and limited
proofs of convergence exist for cyclic graphs– Can we construct a tree from the original
cyclic graph and calculate an lower bound on the solution quality?