Proceedings of the Thirty-Fourth Southeastern Symposium on System Theory (Cat. No.02EX540)

Epicardial signals are time-varying electric potentials on the outer surface of the heart that originate from a signal inside the heart to trigger the heartbeat. Diagnosis of epicardial signals by medical personnel reveals the health of the heart. Modeling of these signals is important in the inverse problem of electrocardiography. In this paper, we present an inverse technique for computing epicardial signals. We present a finite difference method using Laplace's equation for computing the resistance of an arbitrarily shaped conductor. We demonstrate how this method is useful in modeling the currents inside the body due to static electric fields. By applying this method to a model of the human body, we can develop a network of resistors from the heart to various points on the body surface. From actual electrocardiogram (ECG) measurements at the body surface, we can use the derived network to compute source potentials.

False lock is a practical, often very perplexing, problem in phase-lock loops (PLLs). When false lock occurs, the PLL may appear to be operating nominally; the phase detector output may have a nominal (usually small) average value, and a conventional lock detector may indicate a correct phase lock state. However, a static average frequency error exists in the loop. While stable false lock states are the most troubling from a practical standpoint, unstable false lock states are possible. This paper describes a method for analyzing the false lock problem in a broad class of PLLs. A functional differential equation and its first variation are developed for the PLL. A qualitative description is given for the functional differential equation solution that corresponds to a false lock state. The stability of the false lock state is related to a characteristic exponent of the first variation equation with respect to the false lock solution. An approximation is developed for this characteristic exponent, and this is used to determine the stability of the false lock state. Finally, the theory is applied to a simple example, and numerical results are given.

Fault tolerance is a critical issue for teleoperated or autonomous robotic systems that are operating in hazardous and/or remote environments where joint failures are likely. A single joint failure can render an otherwise dexterous manipulator useless. In this article, we examine two measures of fault tolerance. In addition to determining optimally fault tolerant configurations, these measures can be used to control the robot in anticipation of a joint failure and to design fault tolerant robot geometries.

The dynamics of a helicopter are inherently unstable, highly nonlinear and exhibit strong cross-couplings between controls. This paper is concerned with the application of linear adaptive control techniques to stabilize helicopter hover maneuvers. Linear adaptive control techniques enable the de-coupling of multiple-input, multiple-output control problems into simpler single-input, single-Output control problems. This is achieved by using disturbance accommodation control observers to estimate in real-time the effects of all the terms with the exception of nominal effects of the control terms. This approach is inherently robust because the only knowledge of the plant it requires is the approximate representation of the effects of the control. The specific challenge in this application is that, unlike aircraft applications where actuator responses can be accurately modeled, in helicopter the rotors play the role of actuators, and their responses are subject to considerable uncertainty. Numerical results presented here demonstrate that the proposed approach achieves improved tracking of commanded maneuvers, compared to traditional multi-loop designs.

In this paper, we address some of technical challenges associated with supervised tactical mobility behaviors modeling and control of a group of cooperative multi-agent robotic vehicles. Cooperative task planning of robotic systems is a dynamic and complex problem and very challenging. The challenge comes from many avenues including task decomposition, assignment, resource allocation, and task execution and monitoring. Furthermore, the behavior-based control system requires a deliberative and reactive task planning capability for execution of cooperative tasks of mobile robots as well as adequate adaptability to learn new cooperative schemes to improve system performance in over-time. Another challenge of this problem is associated with sensory data gathering, distributed data processing, centralized/decentralized data fusion, and intelligent world perception modeling and comprehension of cooperative mobile robots. We propose a multilayered supervisory control architecture for coordinated task planning of a group of multi-agent robots. The supervisory controller allows control of robotic vehicles in either teleoperation, semi-autonomous, and/or autonomous modes.

This paper presents a prototype of a system for providing improved tornado warnings. The system is capable of being embedded into an automobile to track the position of the vehicle and warn when the vehicle is in the direct path of a tornado, even providing an estimated time of impact. It can also be used in large offices and warehouses that suffer a loss in productivity due to imprecise tornado warnings. The prototype provides exact location of the vehicle or facility using Global Positioning System (GPS) and retrieves the data transmitted by the National Weather Service. In the case of moving vehicles, special algorithms are used to determine the speed and direction of the vehicle. This is then compared to the speed and direction of the possible tornado.

Chất lượng của mối hàn thép hồ quang phụ thuộc rất nhiều vào các thông số của quy trình hàn được sử dụng. Dựa trên một hình học nhất định của mối hàn, các vật liệu hàn tương ứng và các thiết bị cố định các bộ phận, tốc độ cấp nguyên liệu, tốc độ hàn và lượng nhiệt đầu vào đóng một vai trò quan trọng trong phản ứng nhiệt và đàn hồi-plastic của các tấm. Căng thẳng dư và biến dạng tổng thể luôn là mối quan tâm lớn trong các quy trình hàn và nhiều phương pháp mô phỏng đã được phát triển để đánh giá hành vi này. Tuy nhiên, những mô phỏng này rất tốn kém về tính toán, khiến việc tối ưu hóa thiết kế mối hàn trở nên vô cùng tốn kém. Trong bài báo, một tập hợp chiến lược các mô phỏng phần tử hữu hạn của một quy trình hàn điển hình được thực hiện để đào tạo một mô hình mạng nơ-ron, mô hình này có thể được sử dụng để dự đoán hiệu quả phản ứng hàn với một phần nhỏ nỗ lực so với một mô phỏng phần tử hữu hạn tiêu chuẩn.

This paper presents a user-friendly software in modeling daily base case by including the peak power interchange, forecast loads, scheduled generator, and transmission line outages. In order to model an interconnected power system accurately, the items mentioned above must be included into the base case before running the contingency screening. This software will abstract all downloaded files from the NERC web site and process them according to the requested query hour. Finally, the software will create an user defined input batch file (idv file) that will after the base case's power interchange, loads, and scheduled generator and transmission line outages in PSS/E power load flow program. In fact, two versions of this software have been developed with a full power interchange model and a decoupled power interchange model. The decoupled power interchange model is only concentrating on the southern security coordinators' power interchange to the north. The full power interchange model is including all the transactions in that peak hour.

This paper provides a tutorial introduction to phasor measurement units (PMU) when applied in a power system environment, provides an overview of communication alternatives for wide area measurement systems (WAMS), and computes the delay budget for each type of communication link. The goal of this study is to provide data regarding the communication delay that can be incorporated into the analysis and simulation of WAMS.

Modern, large-scale, high-speed process control automation is quite complex in nature. Continuous manufacturing processes currently in use require advanced computer technologies such as simultaneous parallel processing architecture for synchronous process operations that take place independent of each other. In order to optimise the performance of a process control system measured through its output variance, suitably structured robust computing structures are necessary for a multi-input/output process control. This paper describes: (1) a multi-ported-memory, star-ring parallel processing computer architecture for the process control of multiple inputs/outputs; and (2) a suitable parallel processing architecture for optimising the performance of an interconnected process control system. Both the architectures use a feedback control algorithm for multi-input/output process control by measuring its performance through its output product quality and for optimising the performance of the inter-connected process control system by using the product quality output as a performance measure.