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28th Asilomar Conference on Signals, Systems and computers, ACSSC 1994

作者： Wei, Paul Zeidlertt, James R. Ku, Walter H. Department of Electrical and Computer Engineering University of California at San Diego San DiegoCA92093-0407 United States Naval Command Control and Ocean Surveillance Center RDTand E Division Code 804 San DiegoCA92152-5000 United States

ISBN: (纸本)0818664053

This paper studies the ability of the exponentially weighted RLS algorithm to track a doppler shifted BPSK communications signal. This is modeled as a chirped AR1 process in Gaussian white noise. Expressions for the optimum Wiener filter, noise misadjustment, and lag misadjustment are shown. Ft is shown that as in the chirped sinusoid case the error can be written in terms of the forgetting rate β = 1 - Λ of the RLS algorithm;the noise misadjustment is of the order β and lag misadjustment of order 1/β2. However, as the bandwidth of the signal increases the relative lag misadjustment is shown to decrease. © 1995 IEEE.

关键词： White noise

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Stability of switched and hybrid systems

Stability of switched and hybrid systems

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IEEE Conference on Decision and control

作者： M.S. Branicky Laboratory for Information and Decision Systems Department of Electrical Engineering and Computer Science Center for Intelligent Control Systems Massachusetts Institute of Technology USA

This paper outlines some preliminary work on the stability analysis of switched and hybrid systems. The hybrid systems considered are those that combine continuous dynamics, represented by differential or difference equations, with finite dynamics usually thought of as being a finite automaton. Here, we concentrate on the continuous dynamics and model the finite dynamics as switching among finitely many continuous systems. We introduce multiple Lyapunov functions as a tool for analyzing Lyapunov stability of such "switched systems". We use iterated function systems theory as a tool for Lagrange stability. We also discuss the case where the switched systems are indexed by an arbitrary compact set.< >

关键词： Stability Switched systems Difference equations Differential equations Automata Lyapunov method Intelligent control Lagrangian functions control systems Laboratories

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Vibration suppression of unknown flexible payloads using a wrist mounted force/torque sensor for remote manipulator systems

Vibration suppression of unknown flexible payloads using a w...

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IEEE International Conference on Robotics and Automation (ICRA)

作者： S. Jain F. Khorrami Control/Robotics Research Laboratory (CRRL) School of Electrical Engineering & Computer Science Five Metrotech Center Polytechnic University Brooklyn NY USA

The problem of control design for robotic arms manipulating unknown flexible payloads is considered. control design based on neglecting the internal dynamics of the payload will result in degraded performance, increased task execution time, and even failure in performing tasks. At the same time, the characteristics of payloads to be handled vary with application. These considerations make it impractical to outfit the payload with sensors. A novel scheme utilizing a force/torque sensor at the wrist of the manipulator is introduced. A controller utilizing the wrist torque feedback from the sensor is designed as a function of parameters of the payload dynamics. An adaptive scheme for online identification of these parameters and adaptation of controller parameters is discussed. The scheme is implemented on a single-link manipulator carrying a flexible unknown payload. Experimental results validate the fact that the adaptive control maintains a robust performance for high speed slewing and varying payloads.< >

关键词： Payloads Wrist Sensor phenomena and characterization control design Manipulator dynamics Adaptive control Robots Arm Degradation Force sensors

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ERROR PERFORMANCE OF SYNCHRONOUS MULTIUSER CODE-DIVISION MULTIPLE-ACCESS DETECTOR WITH MULTIDIMENSIONAL ADAPTIVE CANCELER

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EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS 1994年第6期5卷 719-724页

作者： SIVESKI, Z BARNESS, Y CHEN, DW Center for Communications and Signal Processing Electrical and Computer Engineering Department New Jersey Institute of Technology University Heights Newark NJ 07102 - USA Was on sabbatical with Delft University of Technology Faculty of Electrical Engineering Telecommunications and Traffic-Control Systems Group Delft - The Netherlands.

A code division multiple access detector that employs a combination of a decorrelator and a multidimensional interference canceler is considered. The weights of the canceler are adaptively controlled using a steepest descent algorithm. The probability of error is evaluated and compared to those of the decorrelating detector and a similar, fixed-weights scheme that requires an estimation of received signal energies. It is shown that the proposed two-stage detector provides substantial improvement over the decorrelating detector, particularly in the presence of strong interfering signals. This is especially noticeable in the high bandwidth efficiency cases. It is also observed that in the presence of weak interferers, the proposed scheme performs better than its fixed-weights counterpart.

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Bootstrapped decorrelating algorithm for adaptive interference cancelation in synchronous CDMA communications systems

Bootstrapped decorrelating algorithm for adaptive interferen...

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IEEE International Symposium on Spread Spectrum Techniques and Applications

作者： Y. Bar-Ness Z. Siveski D.W. Chen Faculty of Electrical Engineering Telecommunications and Traffic-Control Systems Group Delft University of Technnology Delft Netherlands Center for Communications and Signal Processing Electrical and Computer Engineering Department New Jersey Institute of Technology Newark NJ USA

A code division multiple access detector that employs a combination of a correlation detector and a multiuser adaptive interference canceler was previously proposed by the authors. The weights of the canceler are adaptively controlled by the steepest descent algorithm using the minimum power criterion of the canceler outputs. It was shown that such a canceler substantially outperforms the decorrelating detector and has almost the same error probability as a canceler that uses reliable estimates of the received signal energies. In this paper, a different weight control criterion based on minimizing the correlation between the signals at the outputs of the canceler is used, and its performance is compared to that obtained with the minimum power criterion. It is shown that both cancelers have almost the same performance, particularly when SNR is modestly high. Although it is not shown in this paper, we believe that minimizing correlation rather than power outputs is a more suitable criterion when dealing with highly dispersive channels.< >

关键词： Decorrelation Interference cancellation Code division multiplexing Multiaccess communication Detectors Signal processing algorithms Filters Impedance matching Communication system traffic Telecommunication traffic

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Error feedback loops linearize direct digital synthesizers

Error feedback loops linearize direct digital synthesizers

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1994 Second International Conference on Advanced A-D and D-A Conversion Techniques and their Applications

作者： F. Harris B. McKnight Electrical and Computer Engineering Department San Diego State University USA Naval command Control Research & Test and Evaluation Division Ocean Surveillance Center USA

The fidelity of a signal formed by the sequence of recalling stored digital samples from a look-up table and then converting these sample amplitudes to a waveform in a digital-to-analog converter (DAC) is affected by the time and amplitude quantization of the process. The size of the look-up table, hence the number of bits in the addressing scheme, affects the signal's time resolution and results in time-base jitter while the number of bits in the DAC affects amplitude quantization. These errors can be reduced by using noise feedback to spectrally shape the quantization noise formed by the table's address generator and of the quantization noise of the sample values presented to the DAC.< >

关键词： Feedback circuits Digital-analog conversion Frequency synthesizers Quantization Table lookup

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A network approach to integrity maintenance of active object bases

A network approach to integrity maintenance of active object...

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Workshop on Object-Oriented Real-Time Dependable Systems (WORDS)

作者： S.T. Chang P.C.-Y. Sheu L.J. Peterson Department of Electrical and Computer Engineering University of California Irvine CA USA RDT&E Division Naval Command Control and Ocean Surveillance Center San Diego CA USA

The paper describes an asynchronous, network based algorithm to enforce integrity control on top of active objects. It proposes that the control of each active object be expressed as production rules, and the production rules associated with the objects be compiled into a network so that they can be evaluated collectively using databased operations. To maintain correctness and exploit all possible parallelism, each token is time stamped and can be processed asynchronously. To handle rollbacks, a lazy cancellation approach is used. It is shown that, in most cases, the performance of the network approach is superior to that of the fully distributed object oriented approach.

关键词： Object oriented modeling Dynamic programming control systems Continuous production Object oriented databases Parallel processing Computational modeling Real time systems control system synthesis Oceans

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An adaptive fuzzy neural based controller and its application to smart structures

An adaptive fuzzy neural based controller and its applicatio...

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American control Conference (ACC)

作者： I.J. Zeonoun F. Khorrami CRRL Polytechnic Univ. Brooklyn NY USA Control Robotacs Research Laboratory CRRL School of Electrical Engineering Computer Science Six Metrotech Center Polytechnic University Brooklyn NY USA

This paper introduces a fuzzy neural based adaptive controller for simultaneous stabilization and robust performance of a family of plants. The family of plants may be attained from linearization of a nonlinear plant around different operating points or large parameter variations in a given plant. The main idea is to design a sequence of controllers corresponding to the different plants utilizing any standard control design. Thereafter, the obtained controllers will form the basis of the knowledge base of a fuzzy controller capable of deriving a desired crisp output through its inference engine. A neural network is utilized to derive a fuzzy model of the plant and to generate the rule base for the fuzzy logic controller through training. The effectiveness of this new scheme is verified on a smart structure with piezoceramic sensors and actuators.

关键词： Programmable control Adaptive control Fuzzy control Intelligent structures Fuzzy logic Robust control control design Engines Neural networks Fuzzy neural networks

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Adaptive interference suppression for CDMA overlay systems

Adaptive interference suppression for CDMA overlay systems

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MILCOM, Military Communications Conference

作者： P. Wei J.R. Zeidler W.H. Ku Department of Electrical and Computer Engineering University of California San Diego La Jolla CA USA RDT & E Division Naval Command Control and Ocean Surveillance Center San Diego CA USA

It has been proposed that CDMA systems can be assigned to spectral bands which are presently occupied by narrowband users to further increase spectral capacity. Such CDMA overlay systems could provide new options for efficient utilization of the spectrum with minimal disruption to existing narrowband users, especially if adaptive interference suppression techniques are utilized in the spread spectrum receiver. The bit error rate (BER) performance of the mobile-to-base link of a CDMA system for a single narrowband user which occupies a significant portion of the CDMA bandwidth is considered to evaluate the performance of the adaptive filtering. It is shown that adaptive filtering provides a significant improvement when the CDMA and narrowband powers are of the same order. The dependence of the BER on the filter order, the bandwidth of the interference, and its center frequency relative to the CDMA carrier frequency are demonstrated.< >

关键词： Interference suppression Multiaccess communication Frequency Binary phase shift keying Filters Bit error rate Bandwidth Narrowband Phase modulation Fading

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Error performance of the blind decision feedback equalizer using decorrelation

Error performance of the blind decision feedback equalizer u...

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MILCOM, Military Communications Conference

作者： R.E. Kamel Y. Bar-Ness Center for Communications and Signal Processing Department of Electrical and Computer Engineering New Jersey Institute of Technology Newark NJ USA Telecommunications & Traffic-Control Systems Group Delft University of Technnology Delft Netherlands

The decision feedback equalizer has the advantage of compensating for channel amplitude distortion without enhancing noise. Conventional decision feedback equalizers require a training sequence to help them adapt to unknown channel characteristics. Training sequences are not always appropriate. In such situations blind equalizers are more suitable. The blind decision feedback equalizer inherits from the conventional the advantage of not enhancing noise, while compensating for severe ISI. It is thus superior over the blind linear equalizer. On the other hand the blind decision feedback equalizer also suffers from error propagation. In this paper we study the transient behavior of the blind DFE. This is done by deriving an upper bound on the probability of error due to residual ISI and show that it vanishes for the noiseless case. We also determine lower and upper bounds on the probability of error for the additive white Gaussian noise case. The upper bound obtained is the same as that of Duttweiler, et al. (1974). Using a different approach from that of Duttweiler, et al., we derive a lower bound. This bound is tighter than tile "no ISI" lower bound.< >

关键词： Decision feedback equalizers Decorrelation Upper bound Blind equalizers Intersymbol interference Additive white noise Steady-state Convergence Gaussian noise AWGN

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