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IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

作者： H. Direskeneli T.A. Seliga K. Aydin Information and Control Systems Inc. Hampton VA USA Electromagnetics and Remote Sensing Laboratory Department of Electrical Engineering University of Washington Seattle WA USA Communications and Space Scienceences Laboratory Department of Electrical and Computer Engineering Pennslyvania State University University Park PA USA

Apparent reflectivity factors measured by a radar operating at an attenuating wavelength can be adequately predicted by using the reflectivity factors at horizontal and vertical polarizations measured at a non-attenuating wavelength. This capability is important for understanding effects of rainfall on both microwave communication systems and the operation of weather radars operating at attenuating wavelengths. This paper examines and tests this capability by using S-band dual polarization radar measurements to predict C-band radar reflectivity measurements of the same storm but from a different location. The predictions of C-band observations were obtained from disdrometer-derived relationships between S-band reflectivity factor Z/sub H/(10 cm) and differential reflectivity Z/sub DR/ measurements and C-band reflectivity factor Z/sub H/(5 cm) and specific attenuation A/sub H/. Apparent reflectivity factor measurements at C-band, derived from S-band measurements, compared very well with actual measurements in the same storm. The results support the use of the dual polarization radar technique for predicting scattering and attenuation effects of narrow beam microwave signals propagating through rain-filled media along paths other than that traversed by the radar.< >

关键词： Reflectivity Attenuation measurement Wavelength measurement Radar measurements Polarization Radar scattering Storms Microwave communication Meteorological radar Testing

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Worst Case Identification of Continuous time systems via Interpolation

Worst Case Identification of Continuous time Systems via Int...

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American control Conference (ACC)

作者： Jie Chen Guoxiang Gu Carl N. Nett Schools of AeroSpace and Electrical Engineering Georgia Institute of Technology Atlanta GA USA Department of Electrical and Computer Engineering Louisiana State University Baton Rouge LA USA Laboratory for Identification and Control of Complex Highly Uncertain Systems(LIC-CHUS) School of Aerosapce Engineering Georgia Institute of Technology Atlanta GA USA

We consider a worse case control oriented identification problem recently studied by several authors. This problem is one of the H∞ identification in the continuous time setting. We give a less conservative formulation of this problem. The available apriori information consists of a lower bound on the relative stability of the plant, a frequency dependent upper bound on a certain gain associated with the plant, and an upper bound on the noise level. The available experimental information consists of a finite number of noisy plant point frequency response samples. The objective is to identify from the given apriori and experimental information an uncertain model that includes a stable nominal plant model and a bound on the modeling error measured in H∞ norm. Our main contributions include both a new identification algorithm and several new explicit lower and upper bounds on the identification error. The algorithm proposed belongs to the class of interpolatory algorithms which are known to possess a desirable optimality property under a certain criterion. The error bounds presented improve upon the previously available ones in both the aspects of providing a more accurate estimate of the identification error as well as establishing a faster convergence rate for the proposed algorithm.

关键词： Continuous time systems Interpolation Upper bound control systems Frequency Convergence Sampling methods Stability Noise level System identification

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DISTRIBUTED DETECTION WITH CONSULTING SENSORS AND COMMUNICATION COST

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IEEE TRANSACTIONS ON AUTOMATIC control 1992年第9期37卷 1398-1405页

作者： THOMOPOULOS, SCA OKELLO, NN Department of Electrical and Computer Engineering Decision and Control Systems Laboratory Pennslyvania State University University Park PA USA

The problem of distributed detection with consulting sensors in the presence of communication cost associated with any exchange of information (consultation) between sensors is considered. We consider a system of two sensors, S1 and S2, in which S1 is the primary sensor responsible for the final decision u0, while S2 is a consulting sensor capable of relaying its decision u2 to S1 when requested by S1. In the scenario that is considered, the final decision u0 is based either on the raw data available to S1 only, or it may, under certain request conditions, also take into account the decision u2 of sensor S2. Random and nonrandom request schemes are analyzed and numerical results are presented and compared for Gaussian and slow-fading Rayleigh channels. For each decision making scheme, an associated optimization problem is formulated whose solution is shown to satisfy certain a priori set design criteria that we consider essential for sensor fusion.

关键词： Costs Sensor fusion control systems Sensor systems Frequency Communication system control Servomechanisms Steady-state Polynomials Error correction

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EFFICIENT DISTANCE COMPUTATION USING BEST ELLIPSOID FIT

EFFICIENT DISTANCE COMPUTATION USING BEST ELLIPSOID FIT

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1992 IEEE INTERNATIONAL SYMP ON INTELLIGENT control

作者： RIMON, E BOYD, SP Robotics Laboratory Stanford University Department of Computer Science United States Information Systems Laboratory Stanford University Department of Electrical Engineering United States

ISBN: (纸本)0780305469

Knowledge of the distance between a robot and its surrounding environment is vital for any robotic system. The robot must obtain this information rapidly in order to plan and react in real-time. Our technique first surrounds the robot links and the obstacles by optimal ellipsoids, and then computes the clearance of the links from the obstacles with a generalized distance function. This approach offers an attractive alternative to the widely used technique of computing the distance via polyhedral representation of the robot and the obstacles. In particular, our approach offers a drastic reduction in the complexity of the data structures: each polyhedron, typically represented by a list of its features and their adjacency graph;is replaced by a minimum-volume ellipsoid represented by its center and a symmetric matrix whose dimension is either two or three (the workspace dimension). Moreover, while the computation time of the distance between polyhedra is often a function of their geometrical complexity, computation time in the ellipsoidal case is essentially constant;and becomes even more rapid when it is computed repeatedly along the robot's trajectory. Our method consists of the following two algorithms: The first computes the optimal ellipsoid surrounding a convex polyhedron. The second is an analytic formula for the free margin about one ellipsoid with respect to another, that is computed as a standard eigenvalue problem. An efficient incremental version of the latter algorithm is then proposed. This system has been implemented and preliminary simulation results are provided throughout the paper. © 1992 IEEE.

关键词： Geometry

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The segmented bus: A dynamically segmentable interprocessor communication network for intelligent mobile robot systems

The segmented bus: A dynamically segmentable interprocessor ...

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1992 IEEE/RSJ International Conference on Intelligent Robots and systems, IROS 1992

作者： Aras, C.M. Luo, Ren C. Reeves, D.S. Robotics and Intelligent Systems Laboratory Department of Electrical and Computer Engineering United States Department of Computer Science North Carolina State University RaleighNC27695 United States

ISBN: (纸本)0780307372

We propose a new interprocessor communication network, named the Segmented Bus, for multiprocessor message passing computer architectures executing groups of processes with localized communication patterns and time varying computational demands. The control of autonomous robots includes such process sets, making this architecture suitable for the intelligent robot control problem and other control systems with localized and changing message communication patterns. The Segmented Bus also allows dynamic segmentation of the interprocessor communication network for dynamic reconfiguration based on task communication locality. Virtual cut-Through and preemptive circuit switched data transfers are used for inter-segment data transfers on the Segmented Bus. Hardware and protocols for implementing these two techniques are discussed. The performance of the Segmented Bus using the two data transfer techniques is evaluated with simulation and the results are compared to the single bus and the multiple bus in terms of the performance, expandability and the complexity of hardware. © 1992 Institute of electrical and Electronics Engineers Inc. All rights reserved.

关键词： Data transfer

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Visual pattern recognition using morphological methods

Visual pattern recognition using morphological methods

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1992 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 1992

作者： Papadakis, Ioannis N.M. Reisman, James G. Thomopoulos, Stelios C.A. Decision and Control Systems Laboratory Department of Electrical and Computer Engineering Pennsylvania State University University ParkPA16802 United States

ISBN: (纸本)0780305329

An effective method for visual pattern recognition using morphological techniques is presented. It is shown that it can be successfully used for the recognition of deformed letters. The method extracts morphological information by the successive dilation of an "idealized" letter set. At each stage a properly defined similarity index is computed. The maximum values of the similarity index for each stored letter are compared and are used for the classification decision. In this paper, classification results are presented for a set of deformed capital English letters with a realistic level of deformation. Skeletonization of the deformed pattern is shown to improve the performance of the classification method. The described method can be easily implemented using a parallel architecture. © 1992 IEEE.

关键词： Parallel architectures

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Efficient distance computation using best ellipsoid fit

Efficient distance computation using best ellipsoid fit

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IEEE International Symposium on Intelligent control (ISIC)

作者： E. Rimon S.P. Boyd Robotics Laboratory Department of Computer Science University of Stanford USA Information Systems Laboratory Department of Electrical Engineering University of Stanford USA

The effectiveness of the ellipsoid representation for geometrical reasoning is demonstrated in the context of robotics. Specifically, a robot collision-detection problem that consists of computing a quantity that reflects, as a function of the geometrical data, the amount of clearance between the robot and its environment is discussed. The method consists of two algorithms. The first computes the optimal ellipsoid surrounding a convex polyhedron. The second computes an analytic formula for the free margin about one ellipsoid with respect to another, as a standard eigenvalue problem. An efficient incremental version of the latter algorithm is proposed. This system has been implemented, and preliminary simulation results are provided.< >

关键词： Ellipsoids Robots Shape measurement Laboratories Computational modeling Application software computer science Information systems Data structures Eigenvalues and eigenfunctions

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The Segmented Bus: A Dynamically Segmentable Interprocessor Communication Network For Intelligent Mobile Robot systems

The Segmented Bus: A Dynamically Segmentable Interprocessor ...

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IEEE International Workshop on Intelligent Robots and systems (IROS)

作者： C.M. Aras Ren C. Luo D.S. Reeves Department of Electrical and Computer Engineering Robotics and Intelligent Systems Laboratory North Carolina State University Raleigh NC USA

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Binary Hypothesis Testing using Structured Adaptive Networks

Binary Hypothesis Testing using Structured Adaptive Networks

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American control Conference (ACC)

作者： Ioannis N. M. Papadakis Stelios C. A. Thomopoulos Decision and Control Systems Laboratory Department of Electrical and Computer Engineering Pennsylvania State University University Park PA USA

The design of binary hypothesis tests in the absence of any statistical information, based only on a set of available observations is studied. A Structured Adaptive Network (SAN) configuration for the design of such tests based on several criteria of optimality, is presented and certain key asymptotic properties of these criteria are established.

关键词： Testing Adaptive systems Storage area networks Programmable control Adaptive control Light rail systems Gold

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Modified output error method with parameter mismatch compensation for improved performance model reference adaptive control

Modified output error method with parameter mismatch compens...

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IEEE Conference on Decision and control

作者： I.N.M. Papadakis S.C.A. Thomopoulos Decision and Control Systems Laboratory Department of Electrical and Computer Engineering Pennsylvania State University University Park PA USA

A method for model reference adaptive control (MRAC) with improved transient performance is introduced. It is shown that with this method the zero-state output error can be made arbitrarily small. For the linear system case, the value of the high frequency gain, k/sub p/, of the plant does not have to be known a priori, i.e., some uncertainty on k/sub p/ is allowed. The structure of the proposed controller allows for existing convergence results such as exponential convergence of output and parameter errors in the presence of sufficiently rich reference inputs to remain valid. It is also shown that the proposed controller demonstrates improved robustness in the presence of bounded disturbances and/or modeled dynamics, as well as in the case in which adaptation is switched off.< >

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