3,182 research outputs found
On the Co-Design of AV-Enabled Mobility Systems
The design of autonomous vehicles (AVs) and the design of AV-enabled mobility
systems are closely coupled. Indeed, knowledge about the intended service of
AVs would impact their design and deployment process, whilst insights about
their technological development could significantly affect transportation
management decisions. This calls for tools to study such a coupling and
co-design AVs and AV-enabled mobility systems in terms of different objectives.
In this paper, we instantiate a framework to address such co-design problems.
In particular, we leverage the recently developed theory of co-design to frame
and solve the problem of designing and deploying an intermodal Autonomous
Mobility-on-Demand system, whereby AVs service travel demands jointly with
public transit, in terms of fleet sizing, vehicle autonomy, and public transit
service frequency. Our framework is modular and compositional, allowing one to
describe the design problem as the interconnection of its individual components
and to tackle it from a system-level perspective. To showcase our methodology,
we present a real-world case study for Washington D.C., USA. Our work suggests
that it is possible to create user-friendly optimization tools to
systematically assess costs and benefits of interventions, and that such
analytical techniques might gain a momentous role in policy-making in the
future.Comment: 8 pages, 4 figures. Published in the Proceeding of the 23rd IEEE
Intelligent Transportation Systems Conference, ITSC 2020. arXiv admin note:
substantial text overlap with arXiv:1910.07714, arXiv:2008.0897
Control of Robotic Mobility-On-Demand Systems: a Queueing-Theoretical Perspective
In this paper we present and analyze a queueing-theoretical model for
autonomous mobility-on-demand (MOD) systems where robotic, self-driving
vehicles transport customers within an urban environment and rebalance
themselves to ensure acceptable quality of service throughout the entire
network. We cast an autonomous MOD system within a closed Jackson network model
with passenger loss. It is shown that an optimal rebalancing algorithm
minimizing the number of (autonomously) rebalancing vehicles and keeping
vehicles availabilities balanced throughout the network can be found by solving
a linear program. The theoretical insights are used to design a robust,
real-time rebalancing algorithm, which is applied to a case study of New York
City. The case study shows that the current taxi demand in Manhattan can be met
with about 8,000 robotic vehicles (roughly 60% of the size of the current taxi
fleet). Finally, we extend our queueing-theoretical setup to include congestion
effects, and we study the impact of autonomously rebalancing vehicles on
overall congestion. Collectively, this paper provides a rigorous approach to
the problem of system-wide coordination of autonomously driving vehicles, and
provides one of the first characterizations of the sustainability benefits of
robotic transportation networks.Comment: 10 pages, To appear at RSS 201
Electric Autonomous Mobility-on-Demand: Joint Optimization of Routing and Charging Infrastructure Siting
The advent of vehicle autonomy, connectivity and electric powertrains is
expected to enable the deployment of Autonomous Mobility-on-Demand systems.
Crucially, the routing and charging activities of these fleets are impacted by
the design of the individual vehicles and the surrounding charging
infrastructure which, in turn, should be designed to account for the intended
fleet operation. This paper presents a modeling and optimization framework
where we optimize the activities of the fleet jointly with the placement of the
charging infrastructure. We adopt a mesoscopic planning perspective and devise
a time-invariant model of the fleet activities in terms of routes and charging
patterns, explicitly capturing the state of charge of the vehicles by
resampling the road network as a digraph with iso-energy arcs. Then, we cast
the problem as a mixed-integer linear program that guarantees global optimality
and can be solved in less than 10 min. Finally, we showcase two case studies
with real-world taxi data in Manhattan, NYC: The first one captures the optimal
trade-off between charging infrastructure prevalence and the empty-mileage
driven by the fleet. We observe that jointly optimizing the infrastructure
siting significantly outperforms heuristic placement policies, and that
increasing the number of stations is beneficial only up to a certain point. The
second case focuses on vehicle design and shows that deploying vehicles
equipped with a smaller battery results in the lowest energy consumption:
Although necessitating more trips to the charging stations, such fleets require
about 12% less energy than the vehicles with a larger battery capacity
Short-Haul Revitalization Study Final Report
A feasibility study was performed for an advanced commercial short-haul aircraft to evaluate the potential for increased service for short-haul flights that operate out of regional and community airports. An analysis of potential origin-destination markets and trip distances resulted in a seat capacity selection of 48 passengers and a design range of 600 NM. A down-select of advanced technologies resulted in a hybrid-electric propulsion system being chosen as the primary enabling technology. A conceptual design of the advanced aircraft was developed, and a mission and sizing analysis was performed, comparing variants of the advanced aircraft with different levels of electrification. Fairly aggressive levels of electrification and battery specific energy are needed for the hybridelectric architecture to realize any benefit in terms of total energy cost for the 600 NM design mission. The development and operational costs were estimated for the advanced aircraft and compared to the baseline. This analysis demonstrated the negative effect of the cost to develop the hybrid-electric technology on the eventual operating cost. A market analysis was performed to determine possible passenger demand for the advanced shorthaul aircraft. According to the market analysis, there is potential demand for such an aircraft, but not necessarily in many of the smaller regional and community airports that were the intended beneficiaries of this new aircraft concept
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