Sampling-based Approximation Algorithms for Reachability ...
Transcript of Sampling-based Approximation Algorithms for Reachability ...
* Both authors contributed equally
Sampling-based Approximation Algorithms for Reachability Analysis with Provable Guarantees
Lucas Liebenwein*, Cenk Baykal*, Igor Gilitschenski, Sertac Karaman, Daniela Rus
Distributed Robotics Lab, CSAIL, MIT
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Motion Planning โ What We Wish For
Karaman, Sertac, et al. "Sampling-based algorithms for optimal motion planning." IJRR 2011.
Murray, Sean, et al. "Robot Motion Planning on a Chip." RSS. 2016.
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Motion Planning โ What We Have
The New Nation, 06/28/2015 http://www.squirrel-project.eu/objectives.html
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Reachability Analysis for Online Verification
Infeasible Plan Feasible Plan
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Objective
For given timestep ๐, initial set ๐ณ, dynamics โ(๐ฅ, ๐ข)find reachable set ๐น(๐ณ; ๐)
Initial set ๐ณ Reachable set F(๐ณ;๐)
F(โ ; ๐)
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Objective
For a reachable set ๐น(๐ณ; ๐), generate a subset ๐ฎ โ ๐ณ such that
1 โ ํ ๐ ๐น ๐ณ; ๐ โค ๐ ๐น ๐; ๐ โค ๐ ๐น ๐ณ; ๐
Subset ๐ฎ Underapproximation F(๐ฎ; ๐)
F(โ ; ๐)
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Main Challenge
Evaluating reachability involves reasoning about
โข Initial sets and how they evolve with respect to ๐น(โ ; ๐)
โข State space and curse of dimensionality
โข Trade-off between computation time and accuracy
In general, reachable sets cannot be evaluated (exactly) within a feasible amount of time
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Related Work
Porges, O., et al. (2015) Althoff, M., et al. (2014)
Liu, S.B., et al. (2017)Chen, M., et al. (2017) Erlien, S.M., et al. (2016)
Mitchell, I.M., et al. (2005)
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Method
Initial set ๐ณ
F(โ ; ๐)
Reachable set F(๐ณ;๐)
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Method
Initial set ๐ณ
F(โ ; ๐)
Reachable set F(๐ณ;๐)
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Method
Initial set ๐ณ
F(โ ; ๐)
Reachable set F(๐ณ;๐)
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Method
Initial set ๐ณ
F(โ ; ๐)
Reachable set F(๐ณ;๐)
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Method
Initial set ๐ณ
F(โ ; ๐)
Reachable set F(๐ณ;๐)
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Method
Initial set ๐ณ
F(โ ; ๐)
Reachable set F(๐ณ;๐)
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๐ฟ-Packing
๐ฟ
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๐ฟ
๐ฟ-Packing
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๐ฟ
๐ฟ-Packing
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๐ฟ-Packing
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Reachable Set from ๐ฟ-Packing
Initial set ๐ณ Reachable set F(๐ณ;๐)
F(โ ; ๐)๐ฟ
๐ฅ1
๐ฅ2
๐น(๐ฅ1; ๐)
๐น(๐ฅ2; ๐)
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Reachable Set from ๐ฟ-Packing
Initial set ๐ณ Reachable set F(๐ณ;๐)
F(โ ; ๐)๐ฟ
๐ฅ1
๐ฅ2
๐น ๐ฅ1; ๐ โฉ ๐น(๐ฅ2; ๐)
For a given ๐ฟ-packing, there is an upper bound on volume of ๐น ๐ฅ1; ๐ โฉ ๐น(๐ฅ2; ๐)
Guaranteed underapproximation for user-specified ํ (see paper for formal proof)
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Results: Dubinโs Car with Various Initial Sets
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Dumbbell Lollipop Hedgehog
* Both authors contributed equally
Sampling-based Approximation Algorithms for Reachability Analysis with Provable Guarantees
Lucas Liebenwein*, Cenk Baykal*, Igor Gilitschenski, Sertac Karaman, Daniela Rus
Distributed Robotics Lab, CSAIL, MIT
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