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Competitive Gaussian mixture probability hypothesis density filter for multiple target tracking in the presence of ambiguity and occlusion

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IET RADAR SONAR AND NAVIGATION 2012年第4期6卷 251-262页

作者： Yazdian-Dehkordi, M. Azimifar, Z. Masnadi-Shirazi, M. A. Shiraz Univ Sch Elect & Comp Engn Shiraz Iran

The Gaussian mixture probability hypothesis density (GM-PHD) filter has recently been devised as a closed-form recursion for PHD filter for multiple target tracking. The GM-PHD filter works successfully when targets do not move near each other. However, the estimation performance of the GM-PHD filter degrades when targets are in close proximity, such as occlusion condition. In this study, the authors propose a novel approach to improve this drawback. The proposed method employs a renormalisation scheme to rearrange the weights assigned to each target in GM-PHD recursion. Simulation results achieved for different clutter rates and different probabilities of detection show that the proposed approach significantly improves the overall estimation performance compared with the original GM-PHD filter.

关键词： probability renormalisation scheme filtering methods in signal processing closed-form recursion detection probability Gaussian processes target tracking filtering theory signal processing theory competitive Gaussian mixture probability hypothesis density filter clutter rates multiple target tracking Other topics in statistics

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Performance bound for generalised multilevel-quadrature amplitude modulations constellations in multipath Rayleigh fading channels with imperfect channel estimation

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IET COMMUNICATIONS 2012年第11期6卷 1537-1543页

作者： Souto, N. Dinis, R. Silva, J. C. ISCTE IUL Lisbon Portugal Inst Telecomunicacoes Lisbon Portugal FCT UNL Monte De Caparica Portugal

The authors derive a lower bound on the performance of generalised multilevel quadrature amplitude modulations (MQAM) in time-discrete multipath Rayleigh fading environments with imperfect channel estimation. The bound can be regarded as an extension of the well-known matched filter bound (MFB), taking into account the impact of imperfect channel knowledge. The analytical expressions derived allow the computation of the bit error rate for the different bit streams that can be mapped simultaneously onto M-QAM symbols using a hierarchical approach when unequal bit error protection is desired.

关键词： unequal bit error protection multipath channels time-discrete multipath Rayleigh fading channel environment bit error rate error statistics Modulation and coding methods quadrature amplitude modulation matched filters channel estimation generalised multilevel quadrature amplitude modulation constellation filtering methods in signal processing matched filter bound M-QAM symbol MFB imperfect channel estimation Radio links and equipment Communication channel equalisation and identification Rayleigh channels Other topics in statistics

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Why dolphin biosonar performs so well in spite of mediocre 'equipment'

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IET RADAR SONAR AND NAVIGATION 2012年第6期6卷 566-575页

作者： Au, W. W. L. Martin, S. W. Univ Hawaii Hawaii Inst Marine Biol Kailua HI 96734 USA SPAWAR Syst Ctr San Diego San Diego CA 92152 USA

Dolphins have been found to have an excellent sonar system that is able to detect and recognise targets in noisy and highly reverberant environments. However, their 'equipment' has only mediocre characteristics from a technological sonar perspective. How dolphins perform the biosonar task so well is addressed in this manuscript. Echolocating dolphins have the capability to make fine discrimination of target properties such as wall thickness difference of water-filled cylinders and material differences in metallic plates, and to discriminate and recognise species of fish food. The high temporal resolution of the biosonar signals along with the high dynamic range of its auditory system are critical factors for target discrimination. An experiment in metallic plate composition discrimination suggests that dolphins attended to echoes 20-30 dB below the maximum level. Some of the properties of the dolphin sonar system are fairly mediocre, yet the total performance of the system is often outstanding. When compared to some technological sonar, the energy content of the dolphin sonar signal is not very high, the transmission and receiving beamwidths are fairly large, and the auditory filters are not very narrow. Yet the dolphin sonar has demonstrated excellent capabilities in spite of some mediocre features of its 'hardware.'

关键词： transmission beamwidth receiving beamwidth gain 20 dB to 30 dB auditory filter bioacoustics target recognition signal resolution wall thickness difference fish food species recognition reverberant environment sonar detection signal detection Sonar and acoustic radar metallic plate composition discrimination object recognition target detection filtering methods in signal processing dolphin biosonar system water-filled cylinder auditory system biosonar signal temporal resolution mediocre equipment sonar signal processing fish food species discrimination object detection Image recognition filtering theory metallic plate material difference echolocating dolphin

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Cooperative simultaneous localisation and mapping using independent Rao-Blackwellised filters

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IET COMPUTER VISION 2012年第5期6卷 407-414页

作者： Arturo, G. A. Monica, B. G. Miguel, J. C. Oscar, R. G. David, U. G. Univ Miguel Hernandez Elche Elche Spain

This study focuses on an approach to the multi-robot simultaneous localisation and mapping (SLAM) problem. The authors consider that a team of robots start the map building process from known initial poses and move through the environment observing a set of landmarks. In particular, the authors consider that the robots are equipped with vision sensors and are capable to compute the relative distance to natural visual landmarks. In the proposed approach, each robot computes an own global map and integrates its own observations in it. In addition, each robot is also capable of integrating the measurements obtained by other robots in his own map, thus cooperating to compute a global map using the information provided by all the robots in the team. In this way, each robot in the team builds a different global map. The approach presented here differs from others in the sense that each robot maintains an independent SLAM filter, and still each robot can introduce the observations of other robots in his own map. The authors present a set of experimental results obtained in a simulated environment that validate the proposed approach.

关键词： multirobot simultaneous localisation and mapping problem multi-robot systems filtering theory natural visual landmark Computer vision and image processing techniques mobile robots robot vision SLAM (robots) global map independent SLAM filter map building process Optical, image and video signal processing cooperative simultaneous localisation and mapping Mobile robots independent Rao-Blackwellised filter filtering methods in signal processing vision sensor

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Particle filter for manoeuvring target tracking via passive radar measurements with glint noise

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IET RADAR SONAR AND NAVIGATION 2012年第3期6卷 180-189页

作者： Li, H-W Wang, J. Xidian Univ Natl Lab Radar Signal Proc Xian 710071 Shaanxi Peoples R China

This study investigates the problem of manoeuvring target tracking with passive coherent location (PCL) radar. The main challenge stems from the non-linearities of the dynamic state space and the non-Gaussian measurement noise. The contribution of the study is twofold. First, to deal with the problem of manoeuvring target tracking in the presence of glint noise, an interacting multiple model (IMM) particle filtering (PF) method using multiple time-of-arrival (TOA) measurements from several transmitter-receiver pairs are proposed and evaluated. Second, because tracking precision is sensitive to the configuration of transmitters and receiver stations, the authors provide insight into the influence of the configuration of transmitters and receiver stations on the tracking methods of PCL radar. Simulations illustrate the effectiveness of the proposed method. Compared with conventional IMM algorithm and PF algorithm in different glint noise environments and various configurations of transmitters and receiver stations, the proposed method obtains better estimates of position, velocity and acceleration.

关键词： radar transmitters velocity estimation passive radar position estimation transmitter-receiver pairs glint noise time-of-arrival estimation radar tracking particle filtering (numerical methods) Radar equipment, systems and applications acceleration estimation dynamic state space nonlinearities multiple TOA measurements filtering methods in signal processing radar receivers manoeuvring target tracking problem nonGaussian measurement noise passive radar measurements passive coherent location radar multiple time-of-arrival measurements target tracking interacting multiple model particle filtering method PCL radar

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Multiple-camera lane departure warning system for the automotive environment

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IET INTELLIGENT TRANSPORT SYSTEMS 2012年第3期6卷 223-234页

作者： Cualain, D. O. Glavin, M. Jones, E. Natl Univ Ireland Coll Engn & Informat Connaught Automot Res Grp Galway Ireland

The increasing trend towards the use of image sensors in transportation is driven both by legislation and consumer demands for higher safety and a better driving experience. Awareness of the environment that surrounds a vehicle can make driving and manoeuvring of the vehicle much safer for all road users. The authors present an image-processing method to detect lane departures using video taken from multiple optical cameras that is specifically designed to be in accordance with proposed automotive lane departure warning standards. This multi-camera system is more robust to errors caused by lane marking occlusions, sensor failure and glare that single camera systems can suffer from. The system uses a novel lane marking segmentation algorithm in accordance with international standards for lane markings. This method does not demand the high computational requirements of inverse perspective mapping (IPM) unlike methods proposed in related research. The authors present a method for lane boundary modelling based on subtractive clustering and Kalman filtering, which is within the constraints of automotive standards. Finally, using the cameras intrinsic and extrinsic parameters, the width of the vehicle and guidelines issued by the International Organisation for Standardisation, the authors show how lane departure can be identified. Results are presented that verify the system's high detection rate and robustness to various background interference, lighting conditions and road environments.

关键词： Traffic engineering computing subtractive clustering multiple optical cameras Kalman filtering Kalman filters filtering methods in signal processing inverse perspective mapping multiple-camera lane departure warning system International Organisation for Standardisation Computer vision and image processing techniques automotive environment Optical, image and video signal processing sensor failure image segmentation pattern clustering object detection image-processing method lane departure detection lane marking segmentation algorithm image sensors Image sensors lane boundary modelling automotive lane departure warning standards traffic engineering computing lane marking occlusions

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Generation of coloured acoustic noise samples with non-Gaussian distributions

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IET signal processing 2012年第7期6卷 684-688页

作者： Zao, L. Coelho, R. Mil Inst Engn IME Dept Elect Engn BR-22290270 Rio De Janeiro Brazil

This study proposes a method for generating acoustic noise sequences with different distributions and coloured spectra. The noise samples are obtained by passing a non-Gaussian white noise through a finite impulse response filter. The resulting power spectral density is proportional to 1/f(beta), where beta is a positive power-law exponent. The noise samples pattern is determined by the Kurtosis ratio. The proposed generator is evaluated by comparing real and artificial acoustic noises statistics in the time and frequency domains. The results show that the generated coloured sequences achieved the PSD decaying rate and also the non-Gaussian pattern of the real environmental acoustic noises.

关键词： nonGaussian distributions Kurtosis ratio Probability theory, stochastic processes, and statistics time domain white noise frequency domain finite impulse response filter statistical distributions power spectral density acoustic noise sequences filtering methods in signal processing coloured spectra acoustic noises statistics Acoustic noise, its effects and control positive power-law exponent signal processing theory nonGaussian white noise FIR filters coloured acoustic noise samples acoustic noise Other topics in statistics

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Validity of whitening-matched filter approximation to the Pareto coherent detector

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IET signal processing 2012年第6期6卷 546-550页

作者： Weinberg, G. V. Def Sci & Technol Org Elect Warfare & Radar Div Edinburgh SA 5111 Australia

It has been observed that the coherent multilook detector for targets embedded within Pareto intensity clutter can be approximated by the Gaussian optimal detector, or whitening-matched filter, in a number of real data sets. These correspond to clutter returns obtained from the Defence Science and Technology Organisation's Ingara radar, operating in X-band, at high grazing angles and in a circular spotlight mode. This study will establish conditions under which this can be explained mathematically. The key to this is to apply Stein's method from probability theory to establish rules of thumb to determine the validity of the approximation.

关键词： coherent multilook detector Defence Science and Technology Organisation Ingara radar real data sets X-band matched filters Pareto coherent detector Radar equipment, systems and applications whitening-matched filter approximation filtering methods in signal processing Pareto intensity clutter approximation theory Stein method Gaussian processes Gaussian optimal detector probability theory radar clutter Interpolation and function approximation (numerical analysis) Pareto distribution Other topics in statistics

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Fast tracking algorithm using modified potential function

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IET COMPUTER VISION 2012年第2期6卷 111-120页

作者： Kapoor, R. Dhamija, A. Delhi Technol Univ Dept Elect & Commun Engn Delhi 42 India YMCA Univ Sci & Technol Dept Elect Engn Faridabad Haryana India

This study introduces a new potential function-based modelling approach for real-time object tracking with single camera. Real-time tracking requires the least complex techniques for processing and classification and still provide accurate results. Particle filter-based algorithms allow accurate estimations of the displacement and scaling of the object for tracking, but at the cost of high computational complexity and complicated modelling. Also, the existing single-camera tracking systems lack the ability to predict the direction of motion of the object and their performance is significantly affected by occlusions. This study proposes a new method to address these four key issues. The method is principally based upon the potential function, which has been modified for motion image sequences. Potential function uses the current estimates of nonlinear scaling and drift vector with a priori knowledge of the object to compute the tracking parameters in the form of diffusion matrices. The concept of attractors and repellers inside a potential field has been used in analogy to classify different directions of motion in the image plane, such that the object tends to drift towards the attractors and away from repellers. Attractor for every consecutive pair of frames is estimated using the set of transformations (displacement and scaling) occurred due to the motion in a particular direction. The proposed technique works well with minimal tracking errors and a computational complexity of O(1).

关键词： least complex techniques real-time tracking diffusion matrices cameras computational complexity fast tracking algorithm modified potential function image sequences potential function-based modelling approach matrix algebra particle filter-based algorithms Algebra object tracking motion image sequences drift vector Optical, image and video signal processing image classification Computer vision and image processing techniques filtering methods in signal processing Image sensors image motion analysis minimal tracking errors image plane single-camera tracking systems nonlinear scaling particle filtering (numerical methods) real-time object tracking

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Image enhancement through complex conduction coefficient modifications

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IET IMAGE processing 2012年第8期6卷 1205-1219页

作者： Ahmad, F. Fuhrmann, C. Kerr, P. Fairley, J. Price, S. Durst, B. Tarleton State Univ Dept Engn & Phys Stephenville TX USA USA Waterways Expt Stn Engineer Res & Dev Ctr Dept Army Vicksburg MS 39180 USA

One important term in the diffusion equation applied to image processing is the conduction coefficient. It could be a real or complex function, depending on the chosen diffusion processes. A modification in the form of the application of filter convolution to the real-value conduction coefficient has been recommended for the improvement of the signal-to-noise ratio and the speed by which the diffusion is performed. In this study, the developments of the approximately circularly symmetric two-dimensional Lagrange filter and the Teager operator are presented. They are proposed here for the modification of the complex-value conduction coefficient for the improvement of the image diffusion process. Performance of the proposed modifications is evaluated through simulation and the use of three metrics. Experimental results suggest the validity and applicability of the proposed modifications.

关键词： filtering theory diffusion processes filter convolution image processing complex-value conduction coefficient signal-to-noise ratio Computer vision and image processing techniques image diffusion process approximately circularly symmetric two-dimensional Lagrange filter real-value conduction coefficient Teager operator filtering methods in signal processing Optical, image and video signal processing diffusion equation image enhancement complex conduction coefficient modifications

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