摘要:

In this paper, an integrated ROM‐based current controller is proposed for a three‐phase advanced static reactive power source to achieve such high performance as a clean sinusoidal input line current, continuously adjustable reactive power output capability and a system insensitive to input voltage distortion. Three control schemes are proposed and integrated in the same controller. In addition to the basic scheme, there are two other schemes for either reducing by almost half the switch loss or enhancing the availability of the reactive source when one arm of the converter fails. The space vector representation technique is then used to greatly simplify the modeling process. A small signal is derived and open loop stability analysis is made as well. Finally, a prototype hardware circuit is implemented to verify the validity of the proposed current controller.

ISSN:0253-3839    

DOI:10.1080/02533839.1999.9670449

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

In this paper, exponential stabilization for a class of uncertain systems with time‐varying delay and control constraints is investigated. A bounded and continuous feedback control is constructed, under which global exponential stability of the feedback‐controlled system can be guaranteed. Our result is a nontrivial generalization of our earlier result for delay‐free systems. A numerical example is provided to illustrate the use of our main result.

ISSN:0253-3839    

DOI:10.1080/02533839.1999.9670450

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Active magnetic bearing technology offers a number of advantages over conventional bearings including high speed, low power losses, and low maintenance costs. These benefits can, however, only be achieved by advanced signal processing and control. In this paper, a systematic approach is used to model and control a magnetic bearing system. An analytic model of the magnetic bearing system is derived whose parameters are then optimized to correlate with the measurement data. The control system is then designed based upon the model and the associated modeling error. A multi‐objective control design method that accounts for a set of robust stability and performance requirements is used to design a controller, which is then implemented using a digital signal processor board. The design is verified to improve the performance of the existing system.

ISSN:0253-3839    

DOI:10.1080/02533839.1999.9670451

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

This paper proposes a practical and sequential eigenstructure assignment method for designing a parametric state‐feedback controller in multi‐input linear time‐invariant systems. This approach, which sequentially shifts a prescribed set of self ‐conjugate multiple eigenvalues to the closed‐loop system, can explicitly parameterize in groups, and is very useful.Spectrum‐invariant free parametersare proposed to simultaneously deal with two problems: (i) assigning the desired correspondingeigenvectors and generalized eigenvectorswithin an admissible class, and (ii) minimizing theFrobenius normof the resulting controller gain. The shifting of the uncontrollable mode is discussed in some detail. A scheme for determining the minimum Frobenious norm of the resultant state‐feedback matrix gain is developed. Finally, a numerical example is used for illustration of the proposed method.

ISSN:0253-3839    

DOI:10.1080/02533839.1999.9670452

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A numerical approach is proposed for minimum‐torque trajectory planning (MTTP) of kinematically redundant manipulators between two joint configurations. Different from the traditional pseudoinverse control scheme, the first step of the proposed approach is to use an iterative procedure to transform the MTTP problem into a nonlinear programming (NLP) problem. Then an approach to generate a series of feasible solutions for the NLP problem is proposed. Since a sufficient number of feasible solutions can be easily generated, the optimization process of the NLP problem can be started from different points to search for all the local minima. To show the validity of the proposed approach, a planar three‐link robotic manipulator is included in the simulation example.

ISSN:0253-3839    

DOI:10.1080/02533839.1999.9670453

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Since stationarity, ergodicity and self‐similarity for the discrete wavelet transform of fractional Brownian motion (fBm) processes have been shown in previous works, these characteristics could be applied to extract the parameters of two fBm signals from a mixed fBm signal using time‐average correlation functions. The goal of this paper is to distinguish the two identical power fBm signals from the mixed signal. In this case, we suppose that the mixed signal is available, but information on the parameters of the two fBm signals is not provided. A method is proposed to find the parameters of these two fBm signals. The smaller parameter can be detected from the fractal dimension of the mixed fBm signal. The parameter of the other fBm is estimated by processing the wavelet coefficients of the mixed fBm signal. Finally, the simulation results showed that this approach works well in increasing the difference between the parameters of the two fBms.

ISSN:0253-3839    

DOI:10.1080/02533839.1999.9670454

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Symmetric filters and symmetric extension of image edges have been widely used in wavelet image compression. Since the filters are symmetric, it is possible to take advantage of the symmetric property to reduce the computational complexity for the filtering. In this paper, we present a fast convolution algorithm for the discrete wavelet transform (DWT) and the inverse DWT (IDWT) such that the transform time can be greatly reduced. Compared with regular convolution, the new algorithm can decrease the multiplication operations by nearly one half. Converted into real programming, it sped up the DWT and IDWT in our experiments by at least 12% and 55%, respectively. Incorporated with enhancing zerotree coding, the proposed algorithm results in a rapid and efficient coder. Experimental results showed that the coder is competitive with other high performance coders. The proposed convolution algorithm is also suitable for many types of wavelet‐based coding, including wavelet video coding.

ISSN:0253-3839    

DOI:10.1080/02533839.1999.9670455

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

In this paper, two different techniques of the Global Positioning System (GPS) are investigated to proceed the real time kinematic positioning. The first method is the carrier smoothed code (CSC) technique, in which the pseudoranges and the carrier phase observables are combined to acquire more accurate ranging measurements. In the second method, pseudorange observables are applied for initial position estimation, and carrier phase measurements are used for positioning updates. The ambiguity search (AS) technique is adopted to resolve the carrier phase's integer ambiguity problem. To verify the above algorithms, both static and kinematic experiments were conducted. In the static experiment, two Magnavox 4200 GPS receivers were located on both ends of a fixed baseline 1.21 meters in length. Compared with the steady state triple‐difference solutions, the baseline length errors of the CSC and AS techniques were abouts 0.5 meters (1σ) and 0.2 meters (1σ), respectively. An unmanned boat directed to go through six pre‐specified way points was used in the kinematic experiment. Two Motorola Oncore GPS receivers were installed on the boat and the on‐site reference station, respectively, for relative positioning. The boat trajectories computed by the different methods are shown in the experimental results.

ISSN:0253-3839    

DOI:10.1080/02533839.1999.9670456

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The maximal stability robustness problem for a linear, time‐invariant, multi‐input system's state equations involves the design of a state‐feedback gain controller which simultaneously achieves eigenvalue assignment and maximal stability robustness. In this paper, we propose a practicalsequential eigenstructure assignmentscheme for designing a parametric state‐feedback gain matrix, which sequentially shifts a prescribed set of self‐conjugate multiple eigenvalues to the closed‐loop system in groups. Thespectrum‐invariant free parametersare parameterized explicitly in terms of the extra degrees of freedom offered by the state‐feedback controller matrix beyond eigenvalue shifting, and can be exploited to maximize the largest spectral norm of an additive uncertainty in the closed‐loop system matrix, so that stability is guaranteed. A numerical example of the design method is illustrated.

ISSN:0253-3839    

DOI:10.1080/02533839.1999.9670457

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

In this paper, the bearing, elevation, and range estimation of near‐field wide‐band sources from data observed across an array of sensors is considered. Coherent signal‐subspace processing for bearing estimation is tailored for localization of wide‐band sources located in the near field. For sources located in multiple groups (clusters), a matrix beamformer for dimensionality reduction is utilized to simplify wideband processing. The matrix beamformer is used to maximize the average signal‐to‐noise ratio over cells where sources are likely located. A version of coherent signal subspace processing in cell space, which combines beamforming and focusing, are developed and comparative performances are carried out by means of Monte Carlo simulations.

ISSN:0253-3839    

DOI:10.1080/02533839.1999.9670458

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor