Modeling

Numerical Simulation and Spectral Analysis of Pressure Fluctuations in Vehicle Aerodynamic Noise Generation

Duncan, Bradley D.
Raja Sengupta
Mallick, Swapan
Shock, Rick
Sims-Williams, D. B.
2002

A new approach is proposed and demonstrated for investigation of the spatial structure of fluctuations in unsteady aerodynamics results obtained using CFD. This approach is used in this study to isolate unsteadiness in the flow field due to coherent structures at relatively high frequency from the dominant organized motion, as well as from the computational noise, in unsteady data obtained from CFD simulations. These simulations are performed using the commercial CFD software, PowerFLOW, which employs a Lattice Boltzmann method and a very large-eddy simulation (VLES) model for small-scale...

Integrated development process for automated or driver-assist vehicles

Sousa, Joao Borges de
Misener, James A.
Raja Sengupta
2002

We describe the methodology, tools and technologies for designing and implementing communication and control systems for networked automated or driver assist vehicles. In addressing design, we discuss enabling methodologies and our suite of enabling computational tools for formal modeling, simulation, and implementation. We illustrate our description with design, development and implementation work we have performed for Automated Highway Systems, Autonomous Underwater Vehicles, Mobile Offshore Base, Unmanned Air Vehicles, and Cooperative Adaptive Cruise Control. We conclude with the...

Empirical determination of channel characteristics for DSRC vehicle-to-vehicle communication

Taliwal, Vikas
Jiang, Daniel
Mangold, Heiko
Chen, Chi
Raja Sengupta
2004

Dedicated Short Range Communication (DSRC) wireless band, allocated by the FCC for vehicular communication, constitutes the basis for one of the first vehicular ad-hoc networks/systems that is likely to be deployed. Therefore, it is important to characterize the physical properties of the DSRC channel.In this work we propose that due to the complexity, unpredictability and wide variety of road environments a statistical parametric model should be used to describe the physical channel behavior, and its parameters should be inferred from empirical data.Based on this methodological approach...

Ad-Hoc Medium Access Control Protocol Design and Analysis for Vehicle Safety Communications

Raja Sengupta
Xu, Qing
Mak, Tony
Ko, Jeff
2004

This paper studies the design of ad-hoc Medium Access Control (MAC) protocols for a vehicle or the roadside to send safety messages to other vehicles. Such a protocol is needed by Advanced Vehicle Safety Systems (AVSS) and the national Dedicated Short Range Communications (DSRC) architecture. The problem is formulated to meet the communication requirements of vehicle safety applications and the DSRC multi-channel operation model. We propose several ah-hoc protocols, all based on the principles of repetition coding. Analytical bounds of the protocols' performance are derived. Simulations...

An H/Sub /Spl Infin// Approach to Networked Control

Seiler, P.
Raja Sengupta
2005

In this paper, we study the effect of a network in the feedback loop of a control system. We use a stochastic packet-loss model for the network and note that results for discrete-time linear systems with Markovian jumping parameters can be applied. We measure performance using an H/sub /spl infin// norm and compute this norm via a necessary and sufficient matrix inequality condition. We also derive necessary and sufficient linear matrix inequality (LMI) conditions for the synthesis of the H/sub /spl infin// optimal controller for a discrete-time jump system. Finally, we apply these results...

Distributing Synchronous Programs Using Bounded Queues, a coordinated traffic signal application

Zennaro, Marco
Raja Sengupta
2005

This paper is about the modular compilation and distribution of a sub-class of Simulink programs [10] across networks using bounded FIFO queues. The problem is first addressed mathematically. Then, based on these formal results, a software library for the modular compilation and distribution of Simulink program is given. The performance the library is given. The value of synchronous programming for the next generation of traffic control value is discussed. The adoption of these tools seems to be the natural candidate to address the needs of the traffic engineers. As a case study we present...

Kalman Filter-Based Integration of DGPS and Vehicle Sensors for Localization

Rezaei, Shahram
Raja Sengupta
2007

We present a position estimation scheme for cars based on the integration of global positioning system (GPS) with vehicle sensors. The aim is to achieve enough accuracy to enable in vehicle cooperative collision warning, i.e., systems that provides warnings to drivers based on information about the motions of neighboring vehicles obtained by wireless communications from those vehicles, without use of ranging sensors. The vehicle sensors consist of wheel speed sensors, steering angle encoder, and a fiber optic gyro. We fuse these in an extended Kalman filter. The process model is a dynamic...

Analysis of Channel Access Schemes for Model-based Estimation over Multi-access Networks

Huang, Ching-Ling
Raja Sengupta
2009

This report investigates the performance of model-based estima-tion over multi-access networks and emphasizes on the estimationMSE (mean squared error) while using different channel access schemes:probabilistic (random access), deterministic (round-robin scheduling),and combined (grouped channel access). We propose a mathematicalframework for estimation over a simple multi-access MAC protocol,the slotted ALOHA network. Estimation MSE, its asymptotic be-havior and stability condition are derived for different channel accessmethods. Our quantitative discussion can provide guidelines to...

Decentralized Error-Dependent Transmission Control for Model-Based Estimation Over a Multi-Access Network

Huang, Ching-Ling
Raja Sengupta
2008

This paper is motivated by the estimation problem and active safety design for ITS. We investigate the performance of model-based estimation over a multi-access network and emphasizes on asymptotic time-averaged MSE while using error-dependent transmission control. The performance of this decentralized policy is analyzed and an improved policy is also proposed to achieve robustness in a shared channel. Our results suggest that, while designing communication logic for vehicular safety applications, dynamics of the system and channel congestion should be considered at the same time.

Design of Cooperative Vehicle Safety Systems Based on Tight Coupling of Communication, Computing and Physical Vehicle Dynamics

Fallah, Yaser P.
Huang, ChingLing
Raja Sengupta
Krishnan, Hariharan
2010

One of the main characteristics of a Cyber Physical System (CPS) is the tight coupling of the computing and communications aspects of the system with its physical dynamics. In this paper, we examine this characteristic for a cooperative vehicle safety (CVS) system, and identify how the design and operation of such CPSs should consider this tight coupling. In CVS systems, vehicles broadcast their physical state information over a shared wireless network to allow their neighbors to track them and predict possible collisions. The physical dynamics of vehicle movement and the required accuracy...