Reference
J. R. D. Frejo, A.
Núñez, B. De Schutter, and
E. F. Camacho, "Hybrid model predictive control
for freeway traffic using discrete speed limit signals,"
Transportation Research Part C, vol. 46, pp. 309-325, Sept.
2014.
Abstract
In this paper, two hybrid Model Predictive Control (MPC) approaches for freeway
traffic control are proposed considering variable speed limits (VSL) as
discrete variables as in current real world implementations. These discrete
characteristics of the speed limits values and some necessary constraints for
the actual operation of VSL are usually underestimated in the literature, so we
propose a way to include them using a macroscopic traffic model within an MPC
framework. For obtaining discrete signals, the MPC controller has to solve a
highly non-linear optimization problem, including mixed-integer variables.
Since solving such a problem is complex and difficult to execute in real-time,
we propose some methods to obtain reasonable control actions in a limited
computation time. The first two methods (θ-exhaustive and θ-genetic
discretization) consist of first relaxing the discrete constraints for the VSL
inputs; and then, based on this continuous solution and using a genetic or an
exhaustive algorithm, to find discrete solutions within a distance θ of
the continuous solution that provide a good performance. The second class of
methods split the problem in a continuous optimization for the ramp metering
signals and in a discrete optimization for speed limits. The speed limits
optimization, which is much more time-consuming than the ramp metering one, is
solved by a genetic or an exhaustive algorithm in communication with a
non-linear solver for the ramp metering. The proposed methods are tested by
simulation, showing not only a good performance, but also keeping the
computation time reduced.
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BibTeX
@article{FreNun:14-015,
author = {Frejo, Jos{\'{e}} Ram{\'{o}}n D. and N{\'{u}}{\~{n}}ez, Alfredo
and De Schutter, Bart and Camacho, Eduardo F.},
title = {Hybrid Model Predictive Control for Freeway Traffic Using
Discrete Speed Limit Signals},
journal = {Transportation Research Part C},
volume = {46},
pages = {309--325},
month = sep,
year = {2014}
}