Transcript Slides 2013

Intelligent Patrolling
Sarit Kraus
Department of Computer Science
Bar-Ilan University
Collaborators: Noa Agmon, Gal Kaminka, Efrat Sless
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Physical Security with Bounded
Resources
• Limited security resources prevent full security
coverage at all times; allows adversaries to observe
and exploit patterns in selective patrolling or
monitoring.
• Randomized patrolling or monitoring is necessary.
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Randomized Checkpoints
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Multi-Robot Adversarial Patrol
• Motivation:
• High security facilities
• Large military bases
• Neighborhood watch
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Protecting a Parade: route
is announced
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Protecting a Moving Target:
randomizing the route
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Why Do We Need
Automated Methods for
Randomization?
• People are not good at randomization
• The randomized strategy should depend on:
o the adversary and the defenders’ utilities
o the environment parameters
o the defender’s resources.
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Multi-Robot Adversarial
Patrol: The Environment
• Perimeter
o Divided into segments
o Uniform time-distance
o Robot travels through one segment per time
unit
• Adversary
o Tries to penetrate through the perimeter
o Takes t>0 time units to penetrate
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Robotic Model
• k homogenous robots
• Robotic movement model:
o Robots’ movement is directed
o Turning around “costs” τ time units
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Algorithm Framework
• Patrol algorithm:
o Continue straight with probability p
o Turn around with probability 1-p
• PPD: Probability of Penetration Detection
• p depends on the distance between robots and on the
penetration time.
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Robot Movement
• Optimal: Robots are uniformly placed around the
perimeter
• Coordinated
o If decide to turn around they do it simultaneously
o Preserve uniform distance
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Robot Movement
• Optimal: Robots are uniformly placed around the
perimeter
• Coordinated
– If decide to turn around they do it simultaneously
– Preserve uniform distance
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Robot Movement
• Optimal: Robots are uniformly placed around the
perimeter
• Coordinated
– If decide to turn around they do it simultaneously
– Preserve uniform distance
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Robot Movement
• Optimal: Robots are uniformly placed around the
perimeter
• Coordinated
– If decide to turn around they do it simultaneously
– Preserve uniform distance
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Handling Events
What if a robot needs to inspect the penetration?
• Once a penetration is detected, one robot is extracted
from the team to inspect it
• Coordinated attacks are beneficial to the adversary
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What Happens If
Penetration Detected?
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What Happens If Penetration Detected?
• Robot that detected the penetration will inspect it
• Other k-1 robots will spread uniformly
o To achieve optimal behavior for k-1 robots
Phase 1: k robots (before event), steady state
Phase 2: Reorganization
Phase 3: k-1 robots (after event), steady state
Optimal patrol
known
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Naïve Approach
• Deterministic:
Each robot goes straight to its final position
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Randomized
Reorganization
• Challenges:
o each robot needs to move differently
o How much time to spend on the reorganization?
• We randomized over possible paths
• Finding the strategy is complex, in theory, but we
used heuristics to find it in reasonable time
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Physical Security with Bounded
Resources: Summary
• Randomized patrolling or monitoring is necessary.
• Automated randomization is important
• Interesting problems? [email protected]
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