Jagannathan Sarangapani

Wireless Ad hoc and Sensor Networks : Protocols, Performance, and Control

wireless sensor and robot networks from topology control to communication aspects PDF cooperative control of distributed autonomous systems with applications to wireless sensor networks PDF topology control in wireless sensor networks with a companion simulation tool for teaching and research PDF wireless sensor networks architectures and protocols PDF linear control theory structure robustness and optimization automation and control engineering PDF optimal and robust scheduling for networked control systems automation and control engineering PDF intelligent systems modeling optimization and control automation and control engineering PDF sliding mode control in electro-mechanical systems second edition automation and control engineering PDF optimal and robust estimation with an introduction to stochastic control theory second edition automation and control engineering PDF

A Systems Approach to Viable RFID Implementation in the Supply Chain

This article presents a systems approach to RFID deployment in a supply chain from two perspectives: (1) RFID data-based decision-making at all levels of supply chain and (2) communications infrastructure necessary to provide seamless data and information flow. The main contribution of this article is highlighting the interconnection between these two perspectives and the fact that without tackling these issues simultaneously, no viable solution can be developed. Unlike typical articles in the literature, which solely highlight the potential advantages of RFID technologies, this article aims to provide an overview of the basic challenges of deploying RFID systems in supply networks. By providing visibility, effective RFID implementation in a supply chain can bridge the gap between the shop floor and higher level operations. Such a revolutionary concept changes the traditional “linear” structured supply chains into network-centric supply chains. Based on this concept, this article presents a wide range of RFID applications, ranging from shop floor control to inventory management, and discusses technical and research challenges.

Model-based fault detection, estimation, and prediction for a class of linear distributed parameter systems

This paper addresses a new model-based fault detection, estimation, and prediction scheme for linear distributed parameter systems (DPSs) described by a class of partial differential equations (PDEs). An observer is proposed by using the PDE representation and the detection residual is generated by taking the difference between the observer and the physical system outputs. A fault is detected by comparing the residual to a predefined threshold. Subsequently, the fault function is estimated, and its parameters are tuned via a novel update law. Though state measurements are utilized initially in the parameter update law for the fault function estimation, the output and input filters in the modified observer subsequently relax this requirement. The actuator and sensor fault functions are estimated and the time to failure (TTF) is calculated with output measurements alone. Finally, the performance of detection, estimation and a prediction scheme is evaluated on a heat transfer reactor with sensor and actuator faults.

A testbed architecture for Auto‐ID technologies

Purpose – This paper presents an overview on the Auto‐ID (Automatic Identification) technologies testbed that has been established at the University of Missouri‐Rolla (UMR) with the objective of supporting research, development, and implementation of Auto‐ID technologies in network‐centric manufacturing environments.Design/methodology/approach – UMRs Auto‐ID testbed uses a unique hardware‐in‐the‐loop simulation methodology, which integrates decision‐making model development with the design of networking topology and data routing/scheduling schemes, in order to develop, test, and implement viable Auto‐ID solutions. The methodology is founded on a 3‐level integrated model: controller simulation, distributed controller simulation, and distributed controller simulation with hardware‐in‐the‐loop.Findings – This paper discusses two case studies that highlight the effective use of RFID technology, its potential advantages, challenges, and deficiencies stemming from particular applications. These applications in...

Embeddable modular hardware for multi-functional sensor networks

A multi-layer node is described for multi-functional sensor networks. The generation-4 smart sensor node (G4SSN) is light weight, has a small footprint, and is low power to support dedicated, embedded applications. It has core layers for data sensing, data processing and wireless networking. The modular physical layout is built around a flexible, multi-channel bus architecture and routing protocols are easily tailored. Additional stackable layers and devices can be easily configured and programmed to meet specific application requirements, especially for prototyping and research investigations. The feasibility for high-resolution sensor data acquisition and wireless transmission is demonstrated using the dynamic strain behavior of an instrumented cantilever beam. The G4SSN is adaptable with different hardware components such as different sensor types and radio layer capabilities.

A model-based fault tolerant control design for nonholonomic mobile robots in formation:

In this paper, a new model-based fault tolerant kinematic/torque control law is developed by using backstepping for leader-follower robots in formation. In comparison to the kinematic-based formation controllers, the proposed control law design considers the dynamics of the robots and the formation. Initially, the control law is developed for leader and follower mobile robots under normal operation (i.e., no faults); the stability of the formation is verified using Lyapunov theory. Later, an online model-based fault tolerant design is introduced in the presence of a fault, where the fault could be incipient or abrupt in nature. In other words, the fault is mitigated by adding an extra term into the existing control law, which is a function of the unknown fault dynamics, recovered using a neural network. Using Lyapunov theory, the stability of the fault tolerant control law and the formation errors are guaranteed to converge asymptotically in the presence of faults and system uncertainties. Finally, numerical results are used to verify the theoretical results presented in the paper.

Real-time detection of grip length during fastening of bolted joints: a Mahalanobis-Taguchi system (MTS) based approach

This paper presents a Mahalanobis-Taguchi System (MTS) based methodology that detects grip length of bolted joints in real-time during fastening. Grip length is the length of the unthreaded portion of a bolt shaft. When the total thickness of joining members is greater than the grip length of the bolt, it is called under-grip, which compromises the structural integrity of a joint. In this study, a pneumatic, hand-held, rotary-type tool for bolted joints is integrated with a torque sensor and an optical encoder in order to obtain torque-angle signatures. Then, the signature is processed in real-time using the MTS-based approach in order to detect the grip-length, all of which occurs in real-time as the fastening process is completed. The proposed approach is also applied to detect the presence of re-used fasteners, which is another quality concern since some material properties and physical conditions of bolts and nuts can change if they are reused several times. The proposed approach reads in various characteristics from the torque-angle process signature, including mean and standard deviation of the torque-over-angle and angle-over-torque ratios, total angle turned, and work done during the different stages of the fastening process in order to infer about the quality of the bolted joint. The experimental results show that the proposed approach is successful with an accuracy of over 95% in detecting various grip lengths and presence of re-used fasteners.

Interference mitigation and read rate improvement in RFID‐based network‐centric environments

Purpose – This paper investigates interference mitigation and read rate improvement by using novel power control and graph‐based scheduling schemes for radio frequency identification (RFID) systems.Design/methodology/approach – The first method is a distributed power control (DPC) scheme proposed as an alternative to listen‐before‐talk (LBT) for RFID systems specified under CEPT regulations. The DPC algorithm employs reader transmission power as the system control variable to achieve a desired read range and read rate without causing unwanted interference. The second approach is graph‐based scheduling, which uses a graph coloring‐based approach to temporally separate readers with overlapping interrogation zones. The scheduling of the timeslots is carried out so as to offer better efficiency for each reader.Findings – This paper shows that power control, graph theory, collision probability analysis along with timeslot scheduling schemes can be widely adapted to solve general RFID problems. The study shows ...

Use of Frequency Diversity in Signal Strength based WLAN Location Determination Systems

Literature indicates that frequency diversity can be utilized to compensate channel uncertainties such as multipath fading. Therefore, in this paper it is exploited for improving accuracy in locating stationary and mobile objects in the indoor environment. First, frequency diversity technique is introduced for small scale and temporal variation compensation of received signals and demonstrated analytically that it in fact enhances location accuracy. A novel metric is introduced in selection combining in order to achieve location accuracy through the addition of frequency diversity upon two of the available location determination schemes. The results are evaluated experimentally against the case where there is no frequency diversity for reception by using low cost wireless RF devices such as motes. An asset location tracking system is then devised to both improve accuracy and predict asset movement. Frequency diversity in terms of channel spacing of 55 MHz is evaluated and shown to provide a reduction in location determination error between 18 and 23% when compared to a system without frequency diversity. Finally, results from frequency diversity are compared against the spatial diversity techniques in terms of improvement in location accuracy, power consumption of the transmitter, and hardware and software costs.

Detection of Super Regenerative Receiver Using Amplitude Modulated Stimulation

Super regenerative receivers (SRRs) are utilized in a number of electronic devices and detecting their presence from extended distances is critical for many applications. This paper describes a new technique to detect such devices from extended distances by utilizing the fact that the frequency of the SRR quench oscillator is dependent on the power of the stimulating signal. This technique is a coherent active detection technique, based on modulated stimulation. The SRR is stimulated with an amplitude modulated signal which causes the emissions to become frequency modulated. The recorded emissions are then frequency demodulated and match-filtered with the modulating signal for robust detection. This detection technique is a coherent technique that is not affected by other noncoherent signals in the spectrum, and as such outperforms amplitude detection techniques in terms of success of detection and range.