Year: 2022

1 paper accepted to ACC

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Our paper on closed-form Minkowski sum approximations [1] has been accepted to the American Control Conference!

[1] [doi] J. Guthrie, M. Kobilarov, and E. Mallada, “Closed-Form Minkowski Sum Approximations for Efficient Optimization-Based Collision Avoidance,” in American Control Conference (ACC), 2022, pp. 3857-3864.
[Bibtex] [Abstract] [Download PDF]

Motion planning methods for autonomous systems based on nonlinear programming offer great flexibility in incorporating various dynamics, objectives, and constraints. One limitation of such tools is the difficulty of efficiently representing obstacle avoidance conditions for non-trivial shapes. For example, it is possible to define collision avoidance constraints suitable for nonlinear programming solvers in the canonical setting of a circular robot navigating around $M$ convex polytopes over $N$ time steps. However, it requires introducing $(2+L)MN$ additional constraints and $LMN$ additional variables, with $L$ being the number of halfplanes per polytope, leading to larger nonlinear programs with slower and less reliable solving time. In this paper, we overcome this issue by building closed-form representations of the collision avoidance conditions by outer-approximating the Minkowski sum conditions for collision. Our solution requires only $MN$ constraints (and no additional variables), leading to a smaller nonlinear program. On motion planning problems for an autonomous car and quadcopter in cluttered environments, we achieve speedups of 4.0x and 10x respectively with significantly less variance in solve times and negligible impact on performance arising from the use of outer approximations.

@inproceedings{gkm2022acc,
  abstract = {Motion planning methods for autonomous systems based on nonlinear programming offer great flexibility in incorporating various dynamics, objectives, and constraints. One limitation of such tools is the difficulty of efficiently representing obstacle avoidance conditions for non-trivial shapes. For example, it is possible to define collision avoidance constraints suitable for nonlinear programming solvers in the canonical setting of a circular robot navigating around $M$ convex polytopes over $N$ time steps. However, it requires introducing $(2+L)MN$ additional constraints and $LMN$ additional variables, with $L$ being the number of halfplanes per polytope, leading to larger nonlinear programs with slower and less reliable solving time. In this paper, we overcome this issue by building closed-form representations of the collision avoidance conditions by outer-approximating the Minkowski sum conditions for collision. Our solution requires only $MN$ constraints (and no additional variables), leading to a smaller nonlinear program. On motion planning problems for an autonomous car and quadcopter in cluttered environments, we achieve speedups of 4.0x and 10x respectively with significantly less variance in solve times and negligible impact on performance arising from the use of outer approximations.},
  author = {Guthrie, James and Kobilarov, Marin and Mallada, Enrique},
  booktitle = {American Control Conference (ACC)},
  doi = {10.23919/ACC53348.2022.9867524},
  grants = {CAREER-1752362, CPS-2136324, TRIPODS-1934979},
  month = {6},
  pages = {3857-3864},
  pubstate = {presented},
  record = {accepted Feb. 2022, submitted Oct. 2021},
  title = {Closed-Form Minkowski Sum Approximations for Efficient Optimization-Based Collision Avoidance},
  url = {https://mallada.ece.jhu.edu/pubs/2022-ACC-GKM.pdf},
  year = {2022}
}

1 paper accepted to PSCC

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Our paper on market mechanism for truthful bidding with energy storage [1] have been accepted to The Power Systems Computation Conference!

[1] R. K. Bansal, P. You, D. F. Gayme, and E. Mallada, “A Market Mechanism for Truthful Bidding with Energy Storage,” in Power Systems Computation Conference (PSCC), 2022, pp. 1-9.
[Bibtex] [Abstract] [Download PDF]

This paper proposes a market mechanism for multi-interval electricity markets with generator and storage participants. Drawing ideas from supply function bidding, we introduce a novel bid structure for storage participation that allows storage units to communicate their cost to the market using energy cycling functions that map prices to cycle depths. The resulting market-clearing process–implemented via convex programming–yields corresponding schedules and payments based on traditional energy prices for power supply and per-cycle prices for storage utilization. We illustrate the benefits of our solution by comparing the competitive equilibrium of the resulting mechanism to that of an alternative solution that uses prosumer-based bids. Our solution shows several advantages over the prosumer-based approach. It does not require a priori price estimation. It also incentivizes participants to reveal their truthful costs, thus leading to an efficient, competitive equilibrium. Numerical experiments using New York Independent System Operator (NYISO) data validate our findings.

@inproceedings{bygm2022pscc,
  abstract = {This paper proposes a market mechanism for multi-interval electricity markets with generator and storage participants. Drawing ideas from supply function bidding, we introduce a novel bid structure for storage participation that allows storage units to communicate their cost to the market using energy cycling functions that map prices to cycle depths. The resulting market-clearing process--implemented via convex programming--yields corresponding schedules and payments based on traditional energy prices for power supply and per-cycle prices for storage utilization. We illustrate the benefits of our solution by comparing the competitive equilibrium of the resulting mechanism to that of an alternative solution that uses prosumer-based bids. Our solution shows several advantages over the prosumer-based approach. It does not require a priori price estimation. It also incentivizes participants to reveal their truthful costs, thus leading to an efficient, competitive equilibrium. Numerical experiments using New York Independent System Operator (NYISO) data validate our findings.},
  author = {Bansal, Rajni Kant and You, Pengcheng and Gayme, Dennice F. and Mallada, Enrique},
  booktitle = {Power Systems Computation Conference (PSCC)},
  grants = {CAREER-1752362, TRIPODS-1934979, CPS-2136324},
  month = {7},
  pages = {1-9},
  record = {presented, accepted Feb. 2022, submitted Oct. 2021},
  title = {A Market Mechanism for Truthful Bidding with Energy Storage},
  url = {https://mallada.ece.jhu.edu/pubs/2022-PSCC-BYGM.pdf},
  year = {2022}
}