Modeling

Analysis of Communication Losses in Vehicle Control Problems

Seiler, P.
Sengupta, R.
2006

In this paper we study the effect of communication packet losses in the feedback loop of a control system. Our motivation is derived from vehicle control problems where information is communicated via a wireless local area network. For such problems, we consider a simple packet-loss model for the communicated information and note that results for discrete-time linear systems with Markovian jumping parameters can be applied. The goal is to find a controller (if one exists) such that the closed loop is mean square stable for a given packet loss rate. A linear matrix inequality (LMI)...

BigActors: a Model for Structure-Aware Computation

Pereira, Eloi
Kirsch, Christoph M.
De Sousa, João Borges
Sengupta, Raja
2013

This paper describes a model of computation for structure-aware computing called the BigActor model. The model is a hybrid. It combines the Actor model [1] and the Bigraph model [10]. The contributions of this paper are an operational semantics, an example illustrating how the model supports the concise programming of a mobile agent working in a ubiquitous computing world, a query language enabling a bigActor to observe the world around it, and a definition giving semantics to the feedback loop in control theory in the context of this model. This is followed by three theorems showing how...

Decentralized Diagnosability of Regular Languages is Undecidable

Sengupta, R.
Tripakis, S.
2002

We study decentralized fault diagnosis in the context of discrete-event systems. The objective is for a group of agents (the diagnosers) to determine whether a plant has generated a faulty behavior or not, and this, a bounded number of steps after the fault occurred. The plant is modeled as a finite-state automaton producing sequences of events, over some alphabet. One or more special events model faults. Each diagnoser observes only a subset of events generated by the plant. The diagnosers can communicate their observations, which are delivered without loss and in order, but with all...

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

Huang, Ching-Ling
Sengupta, Raja
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.

Department of Computer Sciences University of Salzburg, Austria

Sengupta, Joshua Love Raja
2025

Data center cloud computing distinguishes computational services such as database transactions and data storage from computational resources such as server farms and disk arrays. Cloud computing enables a software-as-a-service business model where clients may only pay for the service they really need and providers may fully utilize the resources they actually have. The key enabling technology for cloud computing is virtualization. Recent developments, including our own work on virtualization technology for embedded systems, show that service-oriented computing through virtualization may...

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

Fallah, Yaser P.
Huang, ChingLing
Sengupta, Raja
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...

Distributed probabilistic map service

Mahajan, A.
Ko, J.
Sengupta, R.
2002

Maps are a good representation of the information state of a network-centric multi-vehicle system that tracks targets. The map service uses information pushed to it by sensors to compute a probabilistic map, i.e., the conditional density of the location of targets given all the past observations. We have designed the map service to be distributed, i.e. the entities participating in the map service divide the probabilistic mapping task amongst themselves, so that it scales well to large operating environments. We present an architecture and algorithms for implementing such a distributed map...

Distributing Synchronous Systems with Modular Structure

Zennaro, M.
Sengupta, R.
2004

Synchronous programs were introduced to simplify the development of reactive systems hiding the complexity and indeterminism of the interleaving while taking full advantage of possible concurrency. The introduction of communication networks enabled the creation of distributed systems presenting the programmer with a new burden of interleaving and nondeterminism due to the asynchronous communication medium. Again this complexity should be hidden from the user while taking full advantage of the possible concurrency to improve performance. Many algorithms for the automatic distributions of...

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

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

Failure Diagnosis of Dynamic Systems: An Approach Based on Discrete Event Systems

Lafortune, S.
Teneketzis, D.
Sampath, M.
Sengupta, R.
Sinnamohideen, K.
2001

We present the salient features of a methodology for failure diagnosis of dynamic systems that can be modeled as discrete event systems. This methodology was introduced by Sampath et al. for centralized systems and subsequently extended by Debouk et al. (2000) for certain classes of decentralized systems. We discuss how to perform detection and identification of unobservable fault events using diagnosers, which are finite-state automata that are built from the discrete-event model of the system under consideration. Examples of diagnosers are given. Comparisons with other methodologies for...