269 research outputs found
Random finite sets in multi-target tracking - efficient sequential MCMC implementation
Over the last few decades multi-target tracking (MTT) has proved to be a challenging and attractive research topic. MTT applications span a wide variety of disciplines, including robotics, radar/sonar surveillance, computer vision and biomedical research. The primary focus of this dissertation is to develop an effective and efficient multi-target tracking algorithm dealing with an unknown and time-varying number of targets. The emerging and promising Random Finite Set (RFS) framework provides a rigorous foundation for optimal Bayes multi-target tracking. In contrast to traditional approaches, the collection of individual targets is treated as a set-valued state. The intent of this dissertation is two-fold; first to assert that the RFS framework not only is a natural, elegant and rigorous foundation, but also leads to practical, efficient and reliable algorithms for Bayesian multi-target tracking, and second to provide several novel RFS based tracking algorithms suitable for the specific Track-Before-Detect (TBD) surveillance application. One main contribution of this dissertation is a rigorous derivation and practical implementation of a novel algorithm well suited to deal with multi-target tracking problems for a given cardinality. The proposed Interacting Population-based MCMC-PF algorithm makes use of several Metropolis-Hastings samplers running in parallel, which interact through genetic variation. Another key contribution concerns the design and implementation of two novel algorithms to handle a varying number of targets. The first approach exploits Reversible Jumps. The second approach is built upon the concepts of labeled RFSs and multiple cardinality hypotheses. The performance of the proposed algorithms is also demonstrated in practical scenarios, and shown to significantly outperform conventional multi-target PF in terms of track accuracy and consistency. The final contribution seeks to exploit external information to increase the performance of the surveillance system. In multi-target scenarios, kinematic constraints from the interaction of targets with their environment or other targets can restrict target motion. Such motion constraint information is integrated by using a fixed-lag smoothing procedure, named Knowledge-Based Fixed-Lag Smoother (KB-Smoother). The proposed combination IP-MCMC-PF/KB-Smoother yields enhanced tracking
Jointly Tracking and Separating Speech Sources Using Multiple Features and the generalized labeled multi-Bernoulli Framework
This paper proposes a novel joint multi-speaker tracking-and-separation
method based on the generalized labeled multi-Bernoulli (GLMB) multi-target
tracking filter, using sound mixtures recorded by microphones. Standard
multi-speaker tracking algorithms usually only track speaker locations, and
ambiguity occurs when speakers are spatially close. The proposed multi-feature
GLMB tracking filter treats the set of vectors of associated speaker features
(location, pitch and sound) as the multi-target multi-feature observation,
characterizes transitioning features with corresponding transition models and
overall likelihood function, thus jointly tracks and separates each
multi-feature speaker, and addresses the spatial ambiguity problem. Numerical
evaluation verifies that the proposed method can correctly track locations of
multiple speakers and meanwhile separate speech signals
A Hybrid Labeled Multi-Bernoulli Filter With Amplitude For Tracking Fluctuating Targets
The amplitude information of target returns has been incorporated into many
tracking algorithms for performance improvements. One of the limitations of
employing amplitude feature is that the signal-to-noise ratio (SNR) of the
target, i.e., the parameter of amplitude likelihood, is usually assumed to be
known and constant. In practice, the target SNR is always unknown, and is
dependent on aspect angle hence it will fluctuate. In this paper we propose a
hybrid labeled multi-Bernoulli (LMB) filter that introduces the signal
amplitude into the LMB filter for tracking targets with unknown and fluctuating
SNR. The fluctuation of target SNR is modeled by an autoregressive gamma
process and amplitude likelihoods for Swerling 1 and 3 targets are considered.
Under Rao-Blackwell decomposition, an approximate Gamma estimator based on
Laplace transform and Markov Chain Monte Carlo method is proposed to estimate
the target SNR, and the kinematic state is estimated by a Gaussian mixture
filter conditioned on the target SNR. The performance of the proposed hybrid
filter is analyzed via a tracking scenario including three crossing targets.
Simulation results verify the efficacy of the proposed SNR estimator and
quantify the benefits of incorporating amplitude information for multi-target
tracking
Robust Multi-Object Tracking: A Labeled Random Finite Set Approach
The labeled random finite set based generalized multi-Bernoulli filter is a tractable analytic solution for the multi-object tracking problem. The robustness of this filter is dependent on certain knowledge regarding the multi-object system being available to the filter. This dissertation presents techniques for robust tracking, constructed upon the labeled random finite set framework, where complete information regarding the system is unavailable
Estimation and control of multi-object systems with high-fidenlity sensor models: A labelled random finite set approach
Principled and novel multi-object tracking algorithms are proposed, that have the ability to optimally process realistic sensor data, by accommodating complex observational phenomena such as merged measurements and extended targets. Additionally, a sensor control scheme based on a tractable, information theoretic objective is proposed, the goal of which is to optimise tracking performance in multi-object scenarios. The concept of labelled random finite sets is adopted in the development of these new techniques
Advanced signal processing techniques for multi-target tracking
The multi-target tracking problem essentially involves the recursive joint estimation of the state of unknown and time-varying number of targets present in a tracking scene, given a series of observations. This problem becomes more challenging because the sequence of observations is noisy and can become corrupted due to miss-detections and false alarms/clutter. Additionally, the detected observations are indistinguishable from clutter. Furthermore, whether the target(s) of interest are point or extended (in terms of spatial extent) poses even more technical challenges.
An approach known as random finite sets provides an elegant and rigorous framework for the handling of the multi-target tracking problem. With a random finite sets formulation, both the multi-target states and multi-target observations are modelled as finite set valued random variables, that is, random variables which are random in both the number of elements and the values of the elements themselves. Furthermore, compared to other approaches, the random finite sets approach possesses a desirable characteristic of being free of explicit data association prior to tracking. In addition, a framework is available for dealing with random finite sets and is known as finite sets statistics. In this thesis, advanced signal processing techniques are employed to provide enhancements to and develop new random finite sets based multi-target tracking algorithms for the tracking of both point and extended targets with the aim to improve tracking performance in cluttered
environments.
To this end, firstly, a new and efficient Kalman-gain aided sequential Monte Carlo probability hypothesis density (KG-SMC-PHD) filter and a cardinalised particle probability hypothesis density (KG-SMC-CPHD) filter are proposed. These filters employ the Kalman-
gain approach during weight update to correct predicted particle states by minimising
the mean square error between the estimated measurement and the actual measurement received at a given time in order to arrive at a more accurate posterior. This technique identifies and selects those particles belonging to a particular target from a given PHD for state correction during weight computation. The proposed SMC-CPHD filter provides a better estimate of the number of targets. Besides the improved tracking accuracy, fewer particles are required in the proposed approach. Simulation results confirm the improved tracking performance when evaluated with different measures.
Secondly, the KG-SMC-(C)PHD filters are particle filter (PF) based and as with PFs, they require a process known as resampling to avoid the problem of degeneracy. This thesis proposes a new resampling scheme to address a problem with the systematic resampling method which causes a high tendency of resampling very low weight particles especially when a large number of resampled particles are required; which in turn affect state estimation.
Thirdly, the KG-SMC-(C)PHD filters proposed in this thesis perform filtering and not tracking , that is, they provide only point estimates of target states but do not provide connected estimates of target trajectories from one time step to the next. A new post processing step using game theory as a solution to this filtering - tracking problem is proposed. This approach was named the GTDA method. This method was employed in the KG-SMC-(C)PHD filter as a post processing technique and was evaluated using both simulated and real data obtained using the NI-USRP software defined radio platform in a passive bi-static radar system.
Lastly, a new technique for the joint tracking and labelling of multiple extended targets is proposed. To achieve multiple extended target tracking using this technique, models for the target measurement rate, kinematic component and target extension are defined and jointly propagated in time under the generalised labelled multi-Bernoulli (GLMB) filter framework. The GLMB filter is a random finite sets-based filter. In particular, a Poisson mixture variational Bayesian (PMVB) model is developed to simultaneously estimate the measurement rate of multiple extended targets and extended target extension was modelled using B-splines. The proposed method was evaluated with various performance metrics in order to demonstrate its effectiveness in tracking multiple extended targets
Group and extended target tracking with the probability hypothesis density filter
Multiple target tracking concerns the estimation of an unknown and time-varying
number of objects (targets) as they dynamically evolve over time from a sequence
of measurements obtained from sensors at discrete time intervals. In the Bayesian
ltering framework the estimation problem incorporates natural phenomena such
as false measurements and target birth/death. Though theoretically optimal, the
generally intractable Bayesian lter requires suitable approximations. This thesis
is particularly motivated by a rst-order moment approximation known as the
Probability Hypothesis Density (PHD) lter.
The emphasis in this thesis is on the further development of the PHD lter for
handling more advanced target tracking problems, principally involving multiple
group and extended targets. A group target is regarded as a collection of targets
that share a common motion or characteristic, while an extended target is regarded
as a target that potentially generates multiple measurements.
The main contributions are the derivations of the PHD lter for multiple group
and extended target tracking problems and their subsequent closed-form solutions.
The proposed algorithms are applied in simulated scenarios and their estimate
results demonstrate that accurate tracking performance is attainable for certain
group/extended target tracking problems. The performance is further analysed
with the use of suitable metrics.Engineering and Physical Sciences Research Council (EPSRC) Industrial CASE Award Studentshi
Classification-Aided Robust Multiple Target Tracking Using Neural Enhanced Message Passing
We address the challenge of tracking an unknown number of targets in strong
clutter environments using measurements from a radar sensor. Leveraging the
range-Doppler spectra information, we identify the measurement classes, which
serve as additional information to enhance clutter rejection and data
association, thus bolstering the robustness of target tracking. We first
introduce a novel neural enhanced message passing approach, where the beliefs
obtained by the unified message passing are fed into the neural network as
additional information. The output beliefs are then utilized to refine the
original beliefs. Then, we propose a classification-aided robust multiple
target tracking algorithm, employing the neural enhanced message passing
technique. This algorithm is comprised of three modules: a message-passing
module, a neural network module, and a Dempster-Shafer module. The
message-passing module is used to represent the statistical model by the factor
graph and infers target kinematic states, visibility states, and data
associations based on the spatial measurement information. The neural network
module is employed to extract features from range-Doppler spectra and derive
beliefs on whether a measurement is target-generated or clutter-generated. The
Dempster-Shafer module is used to fuse the beliefs obtained from both the
factor graph and the neural network. As a result, our proposed algorithm adopts
a model-and-data-driven framework, effectively enhancing clutter suppression
and data association, leading to significant improvements in multiple target
tracking performance. We validate the effectiveness of our approach using both
simulated and real data scenarios, demonstrating its capability to handle
challenging tracking scenarios in practical radar applications.Comment: 15 page
Multiple Target, Multiple Type Filtering in the RFS Framework
A Multiple Target, Multiple Type Filtering (MTMTF) algorithm is developed
using Random Finite Set (RFS) theory. First, we extend the standard Probability
Hypothesis Density (PHD) filter for multiple types of targets, each with
distinct detection properties, to develop a multiple target, multiple type
filtering, N-type PHD filter, where , for handling confusions among
target types. In this approach, we assume that there will be confusions between
detections, i.e. clutter arises not just from background false positives, but
also from target confusions. Then, under the assumptions of Gaussianity and
linearity, we extend the Gaussian mixture (GM) implementation of the standard
PHD filter for the proposed N-type PHD filter termed the N-type GM-PHD filter.
Furthermore, we analyze the results from simulations to track sixteen targets
of four different types using a four-type (quad) GM-PHD filter as a typical
example and compare it with four independent GM-PHD filters using the Optimal
Subpattern Assignment (OSPA) metric. This shows the improved performance of our
strategy that accounts for target confusions by efficiently discriminating
them
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