1,636 research outputs found
Bayesian Quickest Detection of Propagating Spatial Events
Rapid detection of spatial events that propagate across a sensor network is
of wide interest in many modern applications. In particular, in communications,
radar, environmental monitoring, and biosurveillance, we may observe
propagating fields or particles. In this paper, we propose Bayesian single and
multiple change-point detection procedures for the rapid detection of
propagating spatial events. It is assumed that the spatial event propagates
across a network of sensors according to the physical properties of the source
causing the event. The multi-sensor system configuration is arbitrary and
sensors may be mobile. We begin by considering a single spatial event and are
interested in detecting this event as quickly as possible, while controlling
the probability of false alarm. Using a dynamic programming framework we derive
the structure of the optimal procedure, which minimizes the average detection
delay (ADD) subject to a false alarm probability upper bound. In the rare event
regime, the optimal procedure converges to a more practical threshold test on
the posterior probability of the change point. A convenient recursive
computation of this posterior probability is derived by using the propagation
pattern of the spatial event. The ADD of the posterior probability threshold
test is analyzed in the asymptotic regime, and specific analysis is conducted
in the setting of detecting attenuating random signals. Then, we show how the
proposed procedure is easy to extend for detecting multiple propagating spatial
events in parallel. A method that provides false discovery rate (FDR) control
is proposed. In the simulation section, it is clearly demonstrated that
exploiting the spatial properties of the event decreases the ADD compared to
procedures that do not utilize this information, even under model mismatch.Comment: 14 pages, 5 figure
Extended Object Tracking: Introduction, Overview and Applications
This article provides an elaborate overview of current research in extended
object tracking. We provide a clear definition of the extended object tracking
problem and discuss its delimitation to other types of object tracking. Next,
different aspects of extended object modelling are extensively discussed.
Subsequently, we give a tutorial introduction to two basic and well used
extended object tracking approaches - the random matrix approach and the Kalman
filter-based approach for star-convex shapes. The next part treats the tracking
of multiple extended objects and elaborates how the large number of feasible
association hypotheses can be tackled using both Random Finite Set (RFS) and
Non-RFS multi-object trackers. The article concludes with a summary of current
applications, where four example applications involving camera, X-band radar,
light detection and ranging (lidar), red-green-blue-depth (RGB-D) sensors are
highlighted.Comment: 30 pages, 19 figure
Algorithms for sensor validation and multisensor fusion
Existing techniques for sensor validation and sensor fusion are often based on analytical sensor models. Such models can be arbitrarily complex and consequently Gaussian distributions are often assumed, generally with a detrimental effect on overall system performance. A holistic approach has therefore been adopted in order to develop two novel and complementary approaches to sensor validation and fusion based on empirical data. The first uses the Nadaraya-Watson kernel estimator to provide competitive sensor fusion. The new algorithm is shown to reliably detect and compensate for bias errors, spike errors, hardover faults, drift faults and erratic operation, affecting up to three of the five sensors in the array. The inherent smoothing action of the kernel estimator provides effective noise cancellation and the fused result is more accurate than the single 'best sensor'. A Genetic Algorithm has been used to optimise the Nadaraya-Watson fuser design.
The second approach uses analytical redundancy to provide the on-line sensor status output Ī¼Hā[0,1], where Ī¼H=1 indicates the sensor output is valid and Ī¼H=0 when the sensor has failed. This fuzzy measure is derived from change detection parameters based on spectral analysis of the sensor output signal. The validation scheme can reliably detect a wide range of sensor fault conditions. An appropriate context dependent fusion operator can then be used to perform competitive, cooperative or complementary sensor fusion, with a status output from the fuser providing a useful qualitative indication of the status of the sensors used to derive the fused result.
The operation of both schemes is illustrated using data obtained from an array of thick film metal oxide pH sensor electrodes. An ideal pH electrode will sense only the activity of hydrogen ions, however the selectivity of the metal oxide device is worse than the conventional glass electrode. The use of sensor fusion can therefore reduce measurement uncertainty by combining readings from multiple pH sensors having complementary responses. The array can be conveniently fabricated by screen printing sensors using different metal oxides onto a single substrate
Moving target detection in multi-static GNSS-based passive radar based on multi-Bernoulli filter
Over the past few years, the global navigation satellite system (GNSS)-based passive radar (GBPR) has attracted more and more attention and has developed very quickly. However, the low power level of GNSS signal limits its application. To enhance the ability of moving target detection, a multi-static GBPR (MsGBPR) system is considered in this paper, and a modified iterated-corrector multi-Bernoulli (ICMB) filter is also proposed. The likelihood ratio model of the MsGBPR with range-Doppler map is first presented. Then, a signal-to-noise ratio (SNR) online estimation method is proposed, which can estimate the fluctuating and unknown map SNR effectively. After that, a modified ICMB filter and its sequential Monte Carlo (SMC) implementation are proposed, which can update all measurements from multi-transmitters in the optimum order (ascending order). Moreover, based on the proposed method, a moving target detecting framework using MsGBPR data is also presented. Finally, performance of the proposed method is demonstrated by numerical simulations and preliminary experimental results, and it is shown that the position and velocity of the moving target can be estimated accuratel
AudioāVisual Speaker Tracking
Target motion tracking found its application in interdisciplinary fields, including but not limited to surveillance and security, forensic science, intelligent transportation system, driving assistance, monitoring prohibited area, medical science, robotics, action and expression recognition, individual speaker discrimination in multiāspeaker environments and video conferencing in the fields of computer vision and signal processing. Among these applications, speaker tracking in enclosed spaces has been gaining relevance due to the widespread advances of devices and technologies and the necessity for seamless solutions in realātime tracking and localization of speakers. However, speaker tracking is a challenging task in realālife scenarios as several distinctive issues influence the tracking process, such as occlusions and an unknown number of speakers. One approach to overcome these issues is to use multiāmodal information, as it conveys complementary information about the state of the speakers compared to singleāmodal tracking. To use multiāmodal information, several approaches have been proposed which can be classified into two categories, namely deterministic and stochastic. This chapter aims at providing multimedia researchers with a stateāofātheāart overview of tracking methods, which are used for combining multiple modalities to accomplish various multimedia analysis tasks, classifying them into different categories and listing new and future trends in this field
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