Modeling

Handling Cut-In Vehicles in Strings of Cooperative Adaptive Cruise Control Vehicles

Milanés, Vicente
Shladover, Steven E.
2016

Cooperative adaptive cruise control (CACC) systems are a candidate to improve highway capacity by shortening headways and attenuating traffic disturbances. Although encouraging results have been obtained until now, a wide range of traffic circumstances has to be investigated in order to get reliable CACC systems driving on real roads. Among them, handling both vehicle-to-vehicle (V2V) communications-equipped and unequipped vehicles merging into the string of CACC vehicles is a commonly mentioned challenge. In this article, an algorithm for managing the transitions in response to cut-ins...

Vehicle Modelling and Control for Automated Highway Systems

McMahon, D. H.
Hedrick, J. K.
Shladover, S. E.
1990

This study evaluates the feasibility of longitudinal control of a platoon of automated vehicles. As a prerequisite to controller design, a nine state nonlinear model including an internal combustion engine, engine transmission dynamics, and tire friction characteristics has been developed. Parametric studies revealed that simple linear models cannot predict the vehicle transients. Due to this highly nonlinear nature of the vehicle, the use of a nonlinear controller was proposed. A nonlinear control strategy using throttle engine control for a platoon of two vehicles was studied using the...

Modeling, Design and Implementation of Longitudinal Control Algorithm for Automated Vehicle Merging

Lu, Xiao-Yun
Tan, Han-Shue
Shladover, Steven E.
Hedrick, J. Karl
2000

This report presents the work on the development of the regulation layer for automated merging. It includes system modeling, control system synthesis, theoretical analysis and real-rime implementation and field test. The essential part is a rather general adaptive merging algorithm. Key words: automated highway systems, advanced vehicle merging maneuvers, automated vehicle merging maneuvers, longitudinal control, speed control, distance control, vehicle platooning, virtual platooning, adaptive realtime merging algorithm, back-stepping control, magnet distance measurement

Novel Algorithm for Variable Speed Limits and Advisories for a Freeway Corridor with Multiple Bottlenecks

Lu, Xiao-Yun
Shladover, Steven E.
Jawad, Iman
Jagannathan, Ram
Phillips, Thomas
2015

Most previous algorithms for variable speed limit and variable speed advisory (VSL-VSA) for bottleneck flow maximization are local and occupancy measurement–based. Some algorithms for freeway networks with multiple bottlenecks were proposed on the basis of the second-order METANET model, but these were rather complicated. This paper proposes (a) a novel simple VSL-VSA control algorithm for bottleneck flow improvement based on speed measurements and (b) a strategy to expand to a freeway network with multiple bottlenecks by using a distance-based interpolation. The algorithm was validated...

MPC-Based Variable Speed Limit and its Impact on Traffic with V2I Type ACC

Lu, Xiao-Yun
Shladover, Steven
2018

Previous microscopic simulation work of [1] intended to maximize freeway bottleneck flow using Variable Speed Limit (VSL) determined by simple feedback control at the most downstream bottleneck. VSL in other sections upstream are simply determined by distance-based interpolation. The main contributions of this paper are: (a) to expand the feedback control approaches at the most downstream bottleneck; (b) to determine the VSL in other upstream sections through a Model Predictive Control (MPC) with a 2nd order METANET model; (c) Vehicle-to-Infrastructure-to (V2I) ACC (Adaptive Cruise Control...

Truck CACC System Designand DSRC Messages

Lu, Xiao-Yun
Shladover, Steven
2018

This report documents the modeling, control design and implementation logic of the CACC (Cooperative Adaptive Cruise Control).  Intuitively, CACC is based on ACC by adding intervehicle communication. This does not mean that CACC control design is simply adopting ACC control design with DSRC passed information from the forward vehicle(s). The deep reason is that: ACC control does not need to consider string stability in multi-vehicle following since it is for a single vehicle. It is fine as long as the feedback control is robustly stable with respect to all the disturbances from...

Combining Variable Speed Limits with Ramp Metering for Freeway Traffic Control

Lu, Xiao-Yun
Qiu, Tony Z.
Varaiya, Pravin
Horowitz, Roberto
Shladover, Steven E.
2010

This paper proposes a control strategy for combining Variable Speed Limits (VSL) and Ramp Metering (RM) to maximize the flow of a recurrent bottleneck which can be modeled as a lane reduction. The control strategy can be simply described as: (a) Assuming a known ramp metering rate for each onramp; (b) using Finite Time Horizon Model Predictive Control to design VSL for each link; (3) VSL design is based on a simplified 2nd order METANET model with density (or occupancy) and mean speed as the state variables. Simulations are conducted in Matlab with several performance measures to evaluate...

METANET model improvement for traffic control

Lu, Xiao-Yun
Qiu, Tony Z.
Horowitz, Roberto
Chow, Andy
Shladover, Steven
2011

The METANET model, deduced based on equilibrium state assumption, provides a candidate model for freeway traffic control design since it has both speed and density dynamics, but the previous work parameterized the speed control variable to be highly nonlinear, which caused difficulty in control design and implementation. Besides, the model could not catch quick and significant changes in traffic dynamics. This paper suggests improvement on the dynamics model in two aspects: (a) to drop the nonlinear parameterization in the speed control variable for simplicity; and (b) to propose several...

Freeway Micro-simulation Calibration: Case Study Using Aimsun and VISSIM with Detailed Field Data

Lu, Xiao-Yun
Lee, Joyoung
Chen, Danjue
Bared, Joe
Dailey, Daniel
Shladover, Steven E.
2014

A microscopic simulation model is needed to support the development of Variable Speed Limit/Advisory (VSL/VSA) and Speed Harmonization algorithms. The prospective algorithms will be field implemented and tested so the model needs to match the real traffic conditions well before the algorithm can be developed. Detailed field data were collected at key locations along the freeway mainline and onramps and off-ramps for over a week, including flow, speed and occupancy. The compatibility of the data at all locations has been cross-checked by flow conservation, which is accurate enough for...

An Enhanced Microscopic Traffic Simulation Model for Application to Connected Automated Vehicles

Lu, Xiao-Yun
Kan, Xingan (David)
Shladover, Steven E.
Wei, Dali
Ferlis, Robert A.
2017

Modelling detailed microscopic level interactions among classes of vehicles with varying levels of automation and connectivity is essential for evaluating the potential impact or benefit of ACC (Adaptive Cruise Control) and CACC (Cooperative ACC). This requires developing a driving behavior model that is applicable to human-driven vehicles, as well as those equipped with ACC and CACC, and incorporates microscopic level vehicle-to-vehicle interaction. In addition, the model must be validated with the existing freeway data for human-driven vehicles. Microscopic models of this type have been...