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Articles 91 - 99 of 99
Full-Text Articles in Engineering
A Staggered-Diamond Design For Automated/Manual-Hov Highway-To-Highway Interchanges And Constraints On Ahs Design For Accommodating Automated Highway Change, Jacob Tsao
Faculty Publications
This paper consists of two components. The First component addresses a key AHS infrastructure support issue—providing eight extra connector ramps, in addition to the eight existing highway-to-highway connector ramps for the conventional manual traffic, at a highway-to-highway interchange for accommodating continuous automated driving from one highway to the crossing highway. The proposed staggered-diamond design requires only four, instead of eight, separate structures and hence greatly increases the feasibility of AHS infrastructure support. However, the reduced infrastructure complexity at such interchanges could still constrain considerably the design, operation and evolution of AHS. This is the focus of the second component. The …
Stage Definition For Ahs Deployment And An Ahs Evolutionary Scenario, Jacob Tsao
Stage Definition For Ahs Deployment And An Ahs Evolutionary Scenario, Jacob Tsao
Faculty Publications
Pros and cons of various mature Automated Highway Systems (AHS) have been a subject of intense study. However, such discussions are nothing but intellectual exercises unless the issue of how to evolve, in a planned and managed fashion, the current highway systems towards these mature AHS is also addressed. Since full functionality of a mature AHS cannot be realized suddenly, discrete functional steps must be identified and optimized. This paper defines an evolutionary stage towards a mature AHS as any discernible functional increment whose realization may encounter considerable difficulties requiring a significant amount of conscious effort to overcome. A good …
Linearly-Constrained Entropy Maximization Problem With Quadratic Costs And Its Applications To Transportation Planning Problems, Shu-Cherng Fang, Jacob Tsao
Linearly-Constrained Entropy Maximization Problem With Quadratic Costs And Its Applications To Transportation Planning Problems, Shu-Cherng Fang, Jacob Tsao
Faculty Publications
Many transportation problems can be formulated as a linearly-constrained convex programming problem whose objective function consists of entropy functions and other cost-related terms. In this paper, we propose an unconstrained convex programming dual approach to solving these problems. In particular, we focus on a class of linearly-constrained entropy maximization problem with quadratic cost, study its Lagrangian dual, and provide a globally convergent algorithm with a quadratic rate of convergence. The theory and algorithm can be readily applied to the trip distribution problem with quadratic cost and many other entropy-based formulations, including the conventional trip distribution problem with linear cost, the …
A Functional Architecture For Automated Highway Traffic Planning, H.-S. Jacob Tsao
A Functional Architecture For Automated Highway Traffic Planning, H.-S. Jacob Tsao
Faculty Publications
In a fully automated Automated Highway System (AHS), the roadside control system and the vehicles themselves are responsible for moving the large number of vehicles safely and efficiently. Therefore, the task of operating an AHS is drastically different from and much more complex than its conventional counterpart. Resulting from a large number of design options, there exist many possible ways to operate an AHS. Each of these possible operating scenarios will support a different set of functions. A crucial task in AHS R&D is to evaluate and compare these potentially large number of different AHS operating scenarios with respect to …
Defense Industrial Base Policy: Revisited, Michael E. Heberling
Defense Industrial Base Policy: Revisited, Michael E. Heberling
Faculty Publications
In an era of decreasing defense budgets and enemy threats, problems associated with maintaining a healthy defense industrial base have become pronounced. This article discussed defense industrial policy goals and argues that these goals may be collectively unobtainable.
Capacity Of Automated Highway Systems: Effect Of Platooning And Barriers, H.-S. Jacob Tsao, Randolph Hall, Bruce Hongola
Capacity Of Automated Highway Systems: Effect Of Platooning And Barriers, H.-S. Jacob Tsao, Randolph Hall, Bruce Hongola
Faculty Publications
The concept of Automated Highway Systems (AHS) is based on the belief that an appropriate integration of control and communication technologies placed on the vehicle and on the highway can lead to a large improvement in capacity and safety without requiring a significant amount of additional highway right-of-way. Stemming from this belief are various conceptual scenarios for vehicle/highway automation.An AHS consists of two major components: vehicle/highway automation technology and highway operating strategy. In this paper, we study the capacity of key AHS operating scenarios.
A Probabilistic Model For Avcs Longitudinal Collision/Safety Analysis, Jacob Tsao, Randolph Hall
A Probabilistic Model For Avcs Longitudinal Collision/Safety Analysis, Jacob Tsao, Randolph Hall
Faculty Publications
This paper develops a probabilistic model for analyzing longitudinal collision/safety between an abruptly decelerating vehicle and its immediate follower. The input parameters are the length of the gap between the two vehicles, their common speed prior to the failure, the reaction delay of the following vehicle and a bivariate distribution for the two deceleration rates. The output includes the probability of a collision and the probability distribution of the relative speed at collision time We use this model to compare the safety consequences associated with the platooning and “free-agent” longitudinal-separation rules. We also demonstrate that the free-agent rule implemented with …
Constraints On Initial Ahs Deployment And The Concept Definition Of A Shuttle Service For Ahs Debut, Jacob Tsao
Constraints On Initial Ahs Deployment And The Concept Definition Of A Shuttle Service For Ahs Debut, Jacob Tsao
Faculty Publications
Highway automation and its evolution involve a multitude of systems issues. Particularly important and difficult in defining a deployment sequence is the very first step, i.e. the first user service involving fully automated freeway driving. However, this importance and the difficulty imply that many factors may severely constrain the initial deployment. After discussing the paramount importance of initial AHS deployment, this paper points out major high-level issues and constraints. Any realistic deployment strategy must take into consideration gradual technology maturation, introduction of new driver role and diminishing conventional driver role for automated driving, high cost of early-generation automation-equipped vehicles, gradual …
A Probabilistic Model And A Software Tool For Avcs Longitudinal Collision/Safety Analysis, H.-S. Jacob Tsao, Randolph Hall
A Probabilistic Model And A Software Tool For Avcs Longitudinal Collision/Safety Analysis, H.-S. Jacob Tsao, Randolph Hall
Faculty Publications
This paper develops a probabilistic model and a software tool for analyzing longitudinal collision/safety between two automated vehicles. The input parameters are the length of the gap between the two vehicles, the common speed prior to the failure, the reaction delay of the following vehicle and a bivariate pint distribution of the deceleration rates of the two vehicles. The output includes the probability of a collision and also the probability distribution of the relative speed at collision time.We will use this model to compare the safety consequences associated with the platooning and "free-agent" vehicle-following rules. We will also demonstrate that …