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Huber-based unscented filtering and its application to vision-based relative navigation

IET RADAR SONAR AND NAVIGATION 2010年第1期4卷 134-141页

作者： Wang, X. Cui, N. Guo, J. Harbin Inst Technol Harbin 150006 Peoples R China

A new algorithm called Huber-based unscented filtering (UF) is derived and applied to estimate the precise relative position, velocity and attitude of two unmanned aerial vehicles in the formation flight. The relative states are estimated using line-of-sight measurements between the vehicles along with acceleration and angular rate measurements of the follower. By making use of the Huber technique to modify the measurement update equations of standard UF, the new filtering could exhibit robustness with respect to deviations from the commonly assumed Gaussian error probability, for which the standard unscented filtering would exhibit severe degradation in estimation accuracy. Furthermore, contrast to standard extended Kalman filtering, more accurate estimation and faster convergence could be achieved from inaccurate initial conditions. During filter design, the global attitude parameterisation is given by a quaternion, whereas a generalised three-dimensional attitude representation is used to de. ne the local attitude error. A multiplicative quaternion-error approach is used to guarantee that quaternion normalisation is maintained in the filter. Simulation results are shown to compare the performance of the new filter with standard UF and standard extended Kalman filtering for non-Gaussian case.

关键词： acceleration measurements unmanned aerial vehicles Radionavigation and direction finding error statistics parameter estimation global attitude parameterisation Radar equipment, systems and applications vision-based relative navigation remotely operated vehicles angular rate measurements Kalman filtering filtering methods in signal processing Gaussian distribution Gaussian error probability Kalman filters multiplicative quaternion-error local attitude error three-dimensional attitude representation airborne radar line-of-sight measurements aircraft navigation Huber-based unscented filtering

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Highly narrow rejection bandwidth finite impulse response notch filters for communication

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IET COMMUNICATIONS 2010年第18期4卷 2208-2216页

作者： Deshpande, R. Kumar, B. Jain, S. B. RITM Dept Elect & Commun Engn Bangalore 560064 Karnataka India BPIT Dept Elect & Commun Engn New Delhi 110089 India IGIT Dept Elect & Commun Engn Delhi 110006 India

Design of finite impulse response (FIR) notch filters (NFs) with highly narrow rejection bandwidth (RBW) is suggested. RBW is the distance between 3 dB points on the response. Reduction in the RBW is achieved progressively in three stages. In the first stage, an FIR NF is designed from a second order infinite impulse response (IIR) prototype filter. For a given length L of the NF, the authors choose maximum permissible value of 'r' (the pole length of IIR prototype filter) to achieve very narrow RBW of the FIR filter. In the next stage, by using an amplitude change function (ACF): H(z)(2 - H(z)), the designed filter is sharpened. Consequently, the RBW of the resulting NF is reduced to almost half of the earlier value. This reduction of bandwidth makes the resulting NF of length 2L. In the next stage, RBW can be further reduced by the repeated sharpening of the filter by the same ACF.

关键词： FIR NF RBW Digital signal processing filtering methods in signal processing notch filters amplitude change function IIR filters FIR filters infinite impulse response IIR repeated sharpening highly narrow rejection bandwidth finite impulse response notch filters

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Adaptive non-linear filter using a modular polynomial perceptron

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IET signal processing 2010年第6期4卷 640-649页

作者： Zhao, H. Q. Zeng, X. P. Zhang, J. S. Liu, Y. G. Li, T. R. SW Jiaotong Univ Sch Elect Engn Chengdu 610031 Peoples R China SW Jiaotong Univ Sch Informat Sci & Technol Chengdu 610031 Peoples R China Zhejiang Univ Ningbo Inst Technol Ningbo 315100 Zhejiang Peoples R China

This study presents a joint adaptive non-linear filter with pipelined second-order polynomial perceptron (PSOVNN) to reduce the computational complexity and improve the non-linear processing capability of adaptive direct-form second-order Volterra (SOV) filter. The PSOVNN is a nesting modular structure comprising a number of modules that are interconnected in a chained form. Each module is implemented by a small-scale direct-form SOV neural network (SOVNN). These cascaded modules can perform a non-linear mapping from the input space to an intermediate space. In addition, the linear filter of the complete PSOVNN performs a linear mapping from the intermediate space to the output space. A modified real-time recurrent learning (RTRL) algorithm is developed, and its performance is evaluated by a series of simulation experiments. Computer simulations indicate that the proposed non-linear filter exhibits better performance over the direct-form SOV filter with less computational complexity.

关键词： nonlinear filters adaptive nonlinear filter filtering methods in signal processing polynomials signal processing theory pipelined second-order polynomial perceptron computational complexity adaptive filters linear mapping Algebra second-order Volterra filter SOV neural network real-time recurrent learning algorithm

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New approaches to finite impulse response systems identification using higher-order statistics

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IET signal processing 2010年第5期4卷 488-501页

作者： Abderrahim, K. Mathlouthi, H. Msahli, F. Natl Sch Engineers Gabes Gabes 6029 Tunisia Natl Sch Engineers Monastir Monastir 5019 Tunisia

In this study, new approaches for the identification of finite impulse response (FIR) systems using higher-order statistics are proposed. The unknown model parameters are obtained using optimisation algorithms. In fact, the proposed method consists first in defining an optimisation problem and second in using an appropriate algorithm to resolve it. Moreover, a new method is developed for estimating the order of FIR models using only the output cumulants. The results presented in this study illustrate the performance of the proposed methods and compare them with a range of existing approaches.

关键词： identification filtering methods in signal processing signal processing theory higher order statistics unknown model parameters optimisation Other topics in statistics FIR filters higher-order statistics Optimisation techniques finite impulse response systems identification optimisation algorithms

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Quantised H_∞ filtering for networked systems with random sensor packet losses

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IET CONTROL THEORY AND APPLICATIONS 2010年第8期4卷 1339-1352页

作者： Che, W. -W. Wang, J. -L. Yang, G. -H. Nanyang Technol Univ Sch Elect & Elect Engn Singapore 639798 Singapore Northeastern Univ Coll Informat Sci & Engn Shenyang 110004 Peoples R China

This study is concerned with the quantised H-infinity filtering problem for discrete-time systems subject to limited communication capacity, which includes measurement quantisation and random sensor packet losses. By introducing an improved quantised random packet-loss model, the effects of the packet-loss rate and the upper bound of consecutive packet losses and the quantisation on the system performance are considered simultaneously. A quantised H-infinity filter design strategy with the minimised static quantiser range is designed to guarantee the error system exponentially mean-square stable and also achieve the prescribed H-infinity disturbance attenuation level. A numerical example is given to illustrate the effectiveness of the proposed filter design method.

关键词： H∞ control signal processing theory filtering theory mean-square stable Radio links and equipment sensor packet loss Stability in control theory packet-loss rate packet radio networks distributed control measurement quantisation H∞ disturbance attenuation mean square error methods Interpolation and function approximation (numerical analysis) filtering methods in signal processing Optimal control Discrete control systems discrete-time system quantised H∞ filtering discrete time systems asymptotic stability

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Non-uniform time sampling FIR filter design based on least-squares criterion

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ELECTRONICS LETTERS 2010年第23期46卷 1544-1545页

作者： Jin, Z. King, J. Li, X. -D. Sun Yat Sen Univ Sch Informat Sci & Technol Guangzhou 510006 Guangdong Peoples R China S China Agr Univ Sch Engn Guangzhou 510642 Guangdong Peoples R China

The finite impluse response (FIR) digital filter for non-uniform time samples is investigated. By the upsampling technique this filter design is reduced to determining filter coefficients with many zeros. Only those coefficients that are not zeros correspond to time samples which are used to obtain the filtered output. Determining such a set of filter coefficients is exactly a best m-term approximation problem. The optimal non-uniform least-squares filter is obtained by a matching pursuit algorithm. In general, nonzero filter coefficients are not distributed consecutively in order to ensure the better performance of a filter. Satisfactory performances of the present method have been demonstrated by simulation.

关键词： nonuniform least-squares filter least squares approximations filter coefficients filtering methods in signal processing FIR filter FIR filters least-squares criterion matching pursuit algorithm Digital filters m-term approximation Interpolation and function approximation (numerical analysis) time sampling finite impluse response digital filter

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Frequency-domain magnitude constraints for oversampling complex-modulated NPR filter bank system design ensuring prescribed signal-to-distortion ratio

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ELECTRONICS LETTERS 2010年第3期46卷 205-206页

作者： Alfsmann, D. Goeckler, H. G. Ruhr Univ Bochum Digital Signal Proc Grp D-44780 Bochum Germany

Design approaches for oversampling complex-modulated analysis-synthesis filter bank systems (FBSs) have to control multirate disturbances due to down- and upsampling. Common design methods minimise multirate disturbances by optimising an objective function for arbitrarily given filter lengths. In contrast, approximate frequency-domain magnitude constraints are derived for FBS prototype filters such that a prescribed signal-to-distortion ratio of the FBS output signal is ensured. It is shown that these constraints can be met both by linear-phase equiripple and dedicated FBS filter design algorithms. Without the need of occupying the objective function of a (constrained) filter optimisation to minimise FBS disturbance, the resulting performance is close to that achieved with a current design method.

关键词： signal sampling modulation filtering theory linear phase equiripple Integral transforms in numerical analysis filtering methods in signal processing oversampling complex modulated analysis synthesis filter bank discrete Fourier transforms complex modulated NPR filter bank signal-to-distortion ratio filter optimisation frequency-domain analysis frequency domain magnitude constraints

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Fast-converging conjugate-gradient adaptive algorithm for complex channel estimation

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ELECTRONICS LETTERS 2010年第2期46卷 180-181页

作者： Liu, Y. Ranganathan, R. Hunter, M. Mikhael, W. Univ Cent Florida Sch Elect Engn & Comp Sci Orlando FL 32816 USA DME Corp Orlando FL 32826 USA

An efficient adaptive digital filtering algorithm called complex block conjugate least mean square (CBC-LMS) is presented for complex wireless channel estimation. The proposed technique incorporates the conjugate gradient principle into the complex block LMS algorithm. In addition, the novel algorithm generates a unique optimal stepsize along each conjugate direction at each iteration. Computer simulations show that the proposed CBC-LMS yields better performance than existing complex block LMS algorithms, while maintaining computational efficiency.

关键词： Communication channel equalisation and identification wireless channels adaptive digital filtering filtering methods in signal processing complex block LMS algorithm adaptive filters channel estimation conjugate-gradient adaptive algorithm digital filters Interpolation and function approximation (numerical analysis) complex block conjugate least mean square conjugate gradient methods Radio links and equipment complex wireless channel estimation least mean squares methods

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Robust enhancement of fingerprint images obtained by ink method

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ELECTRONICS LETTERS 2010年第20期46卷 1379-1380页

作者： Popovic, B. Bandjur, M. Raicevic, A. Acad Criminalist & Police Studies Belgrade 11080 Serbia Fac Tech Sci K Mitrovica 38220 Serbia

A method for fingerprint enhancement in the frequency domain based on directional log-Gabor filtering is proposed. Experimental results show that the method can successfully enhance even low-quality fingerprint images... 详细信息

关键词： Gabor filters frequency domain directional log-Gabor filtering filtering methods in signal processing Mathematical analysis fingerprint enhancement ink method fingerprint identification frequency-domain analysis Computer vision and image processing techniques image enhancement Image recognition

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Robust high-order matched filter for hyperspectral target detection

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ELECTRONICS LETTERS 2010年第15期46卷 1065-U37页

作者： Shi, Z. Yang, S. Beijing Univ Aeronaut & Astronaut Image Proc Ctr Sch Astronaut Beijing 100191 Peoples R China

A robust high-order matched filter (RHMF) for automatic target detection in hyperspectral images is proposed. The classical detection methods mainly focus on second-order statistics and do not take intrinsic uncertainty or variability of target spectral signatures into account. For automatic target detection in a hyperspectral image, most interesting targets usually occur with low probabilities and small population and they generally cannot be described by second-order statistics. Also, one difficult point in target detection is the inherent variability in target spectral signatures. Under such circumstances, the RHMF algorithm uses high-order statistics, and takes variability into consideration, and has been shown by presented experiments to be more effective than classical detection methods.

关键词： acquisition, processing, storage and dissemination in geophysics robust high-order matched filter geophysical image processing second-order statistics Data and information matched filters higher order statistics Probability theory, stochastic processes, and statistics automatic target detection Geography and cartography computing Computer vision and image processing techniques Other topics in statistics Optical, image and video signal processing hyperspectral images high-order statistics filtering methods in signal processing Geophysical techniques and equipment Instrumentation and techniques for geophysical, hydrospheric and lower atmosphere research object detection

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