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Special Report
Bradley Fellow/Scholar Alumni

 April 2001


Controls and Systems

Associated Laboratories, Groups and Centers:
Center for Rapid Transit Systems
Controls and Systems Group
Digital Signal Processing Research Laboratory
Intelligent Control Engineering Group
Motion Control Systems Research Group

Controls & Systems Faculty
William T. Baumann
A.A. (Louis) Beex
Douglas K. Lindner
Pushkin Kachroo
Richard Moose
Krishnan Ramu
Hugh VanLandingham


Center for Rapid Transit Systems
Krishnan Ramu, Director

Virginia Tech's PERTS friction-free linear propulsion prototype.

Virginia Tech created the Center for Rapid Transit Systems (CRTS) to plan, research, design, develop and demonstrate innovative, energy-efficient, environmentally-friendly technology applications based on Tech's PERTS linear propulsion technology with electromagnetic controls. The center will build a national consortium of industries, federal and state agencies, and other stakeholders to collectively address technology R&D challenges. Using an innovative business model, the CRTS will foster public-private partnerships to advance the development and commercialization of a family of electromagnetically controlled linear propulsion system applications.

Initial CRTS technical activities will focus on further developing and demonstrating a low cost, highly energy-efficient personal electric rapid transit system (PERTS). The PERTS technology represents a unique friction-free electric propulsion technology used to move people and their vehicles in highly congested urban areas. This system will reduce traffic congestion, save energy, improve air quality, reduce accidents, and improve productivity.

The CRTS will subsequently focus on other potential electromagnetically-controlled linear propulsion technology applications including: high rise building cableless elevators, conveyors, airport people movers, heavy lift cargo and logistics management needs, applications in meeting space and aerospace industry needs, and applications responding to a full spectrum of military needs, including electromagnetic systems for aircraft launch and recovery.

Controls and Systems Group

A new project in cooperation with the computer area involves feedback control scheduling for distributed processors. Hybrid feedback control techniques are used to solve the resulting feedback problems and projection dynamics are used to deal with the convexity of the state space. A computer middleware installed on a network has been built for testing and research.

Work continues in applying control theory to problems in intelligent vehicle highway systems. A current project concerns designing feedback controllers for ramp metering, developing online travel time functions, and designing user travel choice models using learning stochastic automata.

Another project aims to create mathematical models for social emotional learning in humans dealing with the emotional quotient (EQ). Future work will deal with developing robotic and web-based systems for interactive EQ learning.

DC power distribution systems on aircraft are the focus of work related to the power electronics area. These systems are highly coupled, nonlinear systems that interact strongly with the generator and loads. Work is focused on the development of nonlinear analysis techniques that will allow the stability regions of the power system to be assessed. Optimization techniques are also being developed to minimize the weight and size of the components of the power system while maximizing the performance of the power system in the presence of two-way power flow.

An interdisciplinary project with the Mechanical Engineering Department to model and control thermo-acoustic instabilities in gas turbine and ramjet engines is continuing. The modeling work involves constructing a nonlinear heat release model from experimental flame measurements. Coupled with our acoustic models, this will allow the prediction of limit cycle amplitudes in test combustors. Additional work in modeling has involved the acoustic analysis of a new industrial gas turbine combustor being built by Honeywell Corporation. The control work has centered on applying and analyzing the performance of simple adaptive algorithms. Least mean squares (LMS) and time averaged gradient (TAG) algorithms have been successfully implemented using acoustic actuators and the work is now focusing on algorithms that use pulse-type inputs characteristic of fuel injectors. In particular, algorithms using subharmonically-pulsed injection are being studied.

Digital Signal Processing Research Laboratory

A.A. (Louis) Beex, Director

A new research effort, jointly with the Time Domain Reflectometry Lab, is aimed at identifying the structure and parameters of a telephone loop from central office measurements. For known structure and parameters, we can then predict the performance of such a loop as a digital communication channel. A recently started effort concerns the DSP implementation of an acoustic sensor array for adaptive beamforming. The challenge here is that the array configuration is not known a priori, as the sensors are only loosely connected, and the array must therefore be self-calibrating. In addition it would be desirable to track one or more moving sources. Our interest in explaining the convergence properties of the class of Affine Projection Algorithms has been extended from correlated data within a datavector to also include correlation between the subsequent datavectors being used for adaptation. The identification of speakers from short utterances, based on our adaptive forced response inverse filtering approach - for finding glottal waveform information -combined with linear prediction parameters, was found to be successful for most speakers exhibiting long pitch periods. However, this algorithmic approach needs further development for speakers with short pitch periods. We have complemented our algorithm for the direct adaptation of line spectral frequencies in a cascade of second order sections with the capability of directly using those parameters in resynthesizing speech. The direct adaptation and synthesis - using line spectral frequencies in second order sections -is being evaluated as a speech coder. Hardware implementation of the latter -as part of a joint research project with the Institute of Technology in Bandung, Indonesia, is currently being considered. Another major aspect of this international project is to develop an efficient image coder based on singularity preservation. The combination of efficient speech and image coders is hoped to lead to a viable MPEG-4 coder.

Intelligent Control Engineering Group

Associated ECE Faculty
Hugh VanLandingham
Pushkin Kachroo

A major focus involves biologically inspired learning algorithms, such as would be found in an artificial immune system, with application to multiple cooperative robots. The roles of the robots would mimic those of certain immune system cells with the ultimate goal of finding adaptive algorithms that model the known processes in mammals. One facet of this work is the development of a Bayesian network that exhibits learning (adaptation) ability. Another facet involves building dynamic-programming-based game theoretic controllers for pursuit evasion in a distributed robotic application. In addition, there is a continuing multidisciplinary effort in the use of fuzzy logic to control ship roll motion and ship-mounted cranes.

Motion Control Systems Research Group

Krishnan Ramu, Director

Sources of acoustic noise are under investigation to develop quiet electric machines and drives with particular reference to switched reluctance machine drive systems. Machine design and control-based noise mitigation algorithms have been developed. Low-cost converter topologies for motor drive systems have been proposed and experimentally verified together with their controllers. New control algorithms for ripple-free performance of switched reluctance and permanent magnet machines have been developed and implemented. These contributions in motion control are expected to significantly affect the product development for the emerging high-volume, but low-cost, variable speed drives market. Due to the technical merits of the proposed topologies and controllers and their low cost, they may open some new applications previously overlooked because of cost considerations.

Representative Projects In Controls & Systems

Computer Networks Loop Reconstruction, Phase III
Electronics for Recurve Actuator
Regenerative Electronics for Launch Vehicles
US-Japan Seminar on Intelligent Distributed Autonomous Power Systems
Behavior Self-Organization in Multi-Agent Learning Systems
Enhanced UML Documentation of an Internet Based Energy Information System
Implications of Automotive/Trucking On-Board Information Systems on General Aviation Cockpit Weather Systems
System Design Methods for Simultaneous Optimal Control of Combustion Instabilities and Efficiency
Development of Modular, Reduced-Order Models for Prediction of Combustion Instabilities


The Bradley Department
of Electrical and Computer Engineering
Virginia Tech

Last Updated, July 15, 2001
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