Farokh Eskafi

AN AUTOMATED HIGHWAY SYSTEM SIMULATOR

Abstract SmartPath is simulation package for an automated highway system (AHS). The program may be used to understand how an AHS would perform under various control policies in terms of highway capacity, traffic flow, and other performance measures of interest to transportation system planners and engineers. SmartPath also can be used to test, simulate, and evaluate the performance of the designs of different modules and instrumentations like engine models, sensors, and communications. The package consists of two separate modules: simulation and animation. The animation program runs on Silicon Graphics workstations and the simulation runs on Sun Spare or Silicon Graphics workstations. The animation program produces a three-dimensional color animation of AHS traffic. SmartPath is a microsimulation: the system elements and the control policies are each individually modeled. The control policies are, for the most part, parametrically specified, so users can study the performance variations by changing the specifications. In this paper, we discuss the modeling of the basic elements of SmartPath. We describe the organization of these elements in the simulation and the assumptions underlying the design, such as availability of certain communication infrastructure and appropriate sensors. We also summarize SmartPaths computational performance.

A new class of B/W halftoning algorithms

A new class of dithering algorithms for black and white (B/W) images is presented. The basic idea behind the technique is to divide the image into small blocks and minimize the distortion between the original continuous-tone image and its low-pass-filtered halftone. This corresponds to a quadratic programming problem with linear constraints, which is solved via standard optimization techniques. Examples of B/W halftone images obtained by this technique are compared to halftones obtained via existing dithering algorithms.

A new class of B/W and color halftoning algorithms

A new class of dithering algorithms for black and white (B/W) and color images is presented. The basic idea behind the technique is to divide the image into small blocks and minimize the distortion between the original continuous tone image and its low-pass filtered halftone. This corresponds to a quadratic programming problem with linear constraints which is solved via the branch and bound algorithm. Examples of B/W and color dither images using the technique are shown and compared to halftones obtained via existing dithering algorithms.<<ETX>>

Design of entry and exit maneuvers for IVHS

Presents design of entry and exit maneuvers for vehicles entering and exiting from automated highway systems (AHS). The authors assume, the traffic on AHS is organized according to the IVHS (intelligent vehicle highway systems) architecture of Varaiya (1993). The authors propose alternative highway configurations for merging and leaving the AHS lanes, either via the transition lane or via dedicated ramps. Communication protocols for coordinating entry and exit maneuvers and lateral and longitudinal control laws to execute these maneuvers are also presented.

The Design of Platoon Maneuvers for IVHS

The use of control and communication technologies in vehicles and in the highway in the form of an Intelligent Vehicle/Highway System or IVHS is an approach that promises to increase capacity without building new roads. Our context is an IVHS system in which traffic is organized in platoons of very closely spaced cars under automatic control. We consider the design of three maneuvers that platoons must undertake: merging (of two platoons into one), splitting (of one platoon into two), and changing lanes. Because of space limitations, only merge is discussed in detail.

Automated Highway Systems

Abstract Automated Highway System (AHS) is an example of a large-scale, multi-agent, hybrid dynamical system. In this paper, the use of computer aided simulation tool for design and evaluation of control laws, for an AHS based on platooning, is outlined. The hierarchical control architecture for AHS is described along with the details of the simulation tool SmartPath. The role of SmartPalh in design and evaluation of AHS control laws is also depicted in the paper.

A general framework for large scale systems development

This paper presents a framework for the modeling, design, simulation and prototyping of large scale systems. It focuses on the specification language SHIFT and the simulation tools used by the framework. It presents the development of an automated highway system as an example.

New class of b/w halftoning algorithms

We present a new class of dithering algorithms for black and white (b/w) images. The basic idea behind our technique is to divide the image into small blocks and minimize the distortion between the original continuous tone image and its low pass filtered halftone. This corresponds to a quadratic programming problem with linear constraints which is solved via standard optimization techniques. Examples of b/w halftone images using our technique are compared to images obtained via error diffusion algorithm.

SIMULATION AND IMPLEMENTATION FRAMEWORK FOR REAL TIME CONTROL ALGORITHMS WITH ITS

We have proposed, investigate,d and implemented a general framework for the simulation, verification, and proto-typing of control algorithms for intelligent vehicles and highways. prior to this project the protocols and control algorithms should have been manually verified, translated to a simulation language for simulation, and then modified for the QNX real-time operating system for porting to the vehicles computer. This manual translation process is error prone at every stage. Our framework performs the translations automatically, and therefore, removes the possibility of the translation errors. The specification of the control algorithms is performed in the SHIFT specification language. An existing verification platform is used to carry out the correctness proofs of the control algorithms. The QNX real-time operating system, which is currently in use at PATH in automated vehicles, is used as the target platform for the generated code.