1 Poisson multi-Bernoulli mixture filter with general target-generated measurements and arbitrary clutter

2025-04-30 0 0 889.41KB 15 页 10玖币
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Poisson multi-Bernoulli mixture filter with general
target-generated measurements and arbitrary clutter
Ángel F. García-Fernández, Yuxuan Xia, Lennart Svensson
Abstract—This paper shows that the Poisson multi-Bernoulli
mixture (PMBM) density is a multi-target conjugate prior for
general target-generated measurement distributions and arbi-
trary clutter distributions. That is, for this multi-target mea-
surement model and the standard multi-target dynamic model
with Poisson birth model, the predicted and filtering densities are
PMBMs. We derive the corresponding PMBM filtering recursion.
Based on this result, we implement a PMBM filter for point-
target measurement models and negative binomial clutter density
in which data association hypotheses with high weights are
chosen via Gibbs sampling. We also implement an extended
target PMBM filter with clutter that is the union of Poisson-
distributed clutter and a finite number of independent clutter
sources. Simulation results show the benefits of the proposed
filters to deal with non-standard clutter.
Index Terms—Multi-target filtering, Poisson multi-Bernoulli
mixtures, Gibbs sampling, arbitrary clutter.
I. INTRODUCTION
Multi-target filtering consists of estimating the current states
of an unknown and variable number of targets based on noisy
sensor measurements up to the current time step. It is a key
component of numerous applications, for example, defense [1],
automotive systems [2] and air traffic control [3]. Multi-target
filtering is usually addressed using probabilistic modelling,
with the main approaches being multiple hypothesis tracking
[4], joint probabilistic data association [5] and random finite
sets [6].
In detection-based multi-target filtering, sensors collect
scans of data that may contain target-generated measurements
as well as clutter, which refers to undesired detections. For
example, in radar, clutter can be caused by reflections from the
environment, such as terrain, sea and rain, or other undesired
objects [7], [8]. Multi-target filters applied to real data must
then account for these clutter measurements for suitable per-
formance, for instance, sea clutter and land clutter in radar data
[9], false detections in image data [10], [11], false detections
in audio visual data [12], and underwater clutter in active sonar
data [13], [14].
In the standard detection model, clutter is modelled as
a Poisson point process (PPP) [6]. The PPP is motivated
by the fact that, for sufficiently high sensor resolution and
independent clutter reflections in each sensor cell, the detection
A. F. García-Fernández is with the Department of Electrical Engineer-
ing and Electronics, University of Liverpool, Liverpool L69 3GJ, United
Kingdom (angel.garcia-fernandez@liverpool.ac.uk). He is also with the
ARIES Research Centre, Universidad Antonio de Nebrija, Madrid, Spain.
Y. Xia and L. Svensson are with the Department of Electrical Engineering,
Chalmers University of Technology, SE-412 96 Gothenburg, Sweden (first-
name.lastname@chalmers.se).
process can be accurately approximated as a PPP [15]. The
PPP is also convenient mathematically and it can be char-
acterised by its intensity function on the single-measurement
space.
For the point-target measurement model, PPP clutter and
the standard multi-target dynamic model with PPP birth, the
posterior is a Poisson multi-Bernoulli mixture (PMBM) [16],
[17]. The PMBM consists of the union of a PPP, representing
undetected targets, and an independent multi-Bernoulli mix-
ture (MBM) representing targets that have been detected at
some point and their data association hypotheses. The posterior
density is also a PMBM for the extended target model [18] and
for a general target-generated measurement model [19], both
with PPP clutter and the standard dynamic model. Extended
target modelling is required when, due to the sensor resolution
and the target extent, a target may generate more than one de-
tection at each time step [20]. This makes the data association
problem considerably more challenging than for point targets.
The general target generated-measurement model includes the
point and extended target cases as particular cases, and can for
example be used when there can be simultaneous point and
extended targets in a scenario [19].
If the birth model is multi-Bernoulli instead of PPP, the
posterior density in the above cases is an MBM, which is
obtained by setting the Poisson intensity of the PMBM filter
to zero and by adding the Bernoulli components of the birth
process in the prediction step. The MBM filter can also be
written in terms of Bernoulli components with deterministic
target existence, which results in the MBM01 filter [17, Sec.
IV]. It is also possible to add unique labels to the target
states in the MBM and MBM01 filters. The (labelled) MBM01
filtering recursions are analogous to the δ-generalised labelled
multi-Bernoulli (δ-GLMB) filtering recursions [21], [22].
All the above recursions to compute the posterior assume
PPP clutter, but other clutter distributions are also important
in various contexts, for instance, to model bursts of radar sea
clutter [23]. For general target-generated measurements and
arbitrary clutter density, the Bernoulli filter was proposed in
[24], and the probabilistic hypothesis density (PHD) filter,
which provides a PPP approximation to the posterior, was
derived in [25]. The corresponding PHD filter update depends
on the set derivative of the logarithm of the probability
generating functional (PGFL) of the clutter process. A version
of this PHD filter update, written in terms of densities, which
is more suitable for implementation than [25], is provided
in [26]. There are also other PHD filter variants with non-
PPP clutter for point targets, for example, a PHD filter with
negative binomial clutter [27], a second order PHD filter with
arXiv:2210.12983v2 [stat.AP] 24 May 2023
Panjer clutter [28], and a linear-complexity cumulant-based
filter for clutter described by its intensity and second-order
cumulant [29], [30]. A cardinalised PHD filter with general
target-generated measurements and arbitrary clutter is derived
in [31]. Another approach is to estimate the states of Bernoulli
clutter generators by including them in the multi-target state
[6], [32].
This paper shows that for general target-generated mea-
surements and arbitrary clutter density, the posterior is also a
PMBM and we derive the filtering recursion. This contribution
extends the family of closed-form recursions to calculate
the posterior to a more general detection-based measurement
model. As a direct result, this paper also derives the corre-
sponding (labelled or not) MBM and MBM01 filters, including
δ-GLMB filters. We also directly obtain the Poisson multi-
Bernoulli (PMB) filter, which can be derived by Kullback-
Leibler divergence minimisation on a target space augmented
with auxiliary variables [16], [33]. We also propose a Gibbs
sampling algorithm for selecting global hypotheses with high
weights [21], [34]–[36] for the PMBM filter for point targets
and clutter that is an independent and an identically distributed
(IID) cluster process [6] with arbitrary cardinality distribution.
We show via simulation results the advantages of the proposed
filter in two scenarios: one scenario for point targets and
IID clutter with negative binomial cardinality distribution, and
another scenario for extended targets where there are a finite
number of clutter sources.
The rest of this paper is organised as follows. Section
II introduces the models and an overview of the PMBM
posterior. The PMBM filter update is presented in Section III.
The Gibbs sampling data association algorithm for point-target
PMBM filtering with arbitrary clutter is proposed in Section
IV. Finally, simulation results and conclusions are provided in
Sections V and VI.
II. MODELS AND OVERVIEW OF THE PMBM POSTERIOR
This section presents the dynamic and measurement models
in Section II-A, and an overview of the PMBM posterior in
Section II-B, with its global hypotheses in Section II-C.
A. Models
A target state is denoted by xand it contains the variables
that describe its current dynamics, such as position and veloc-
ity, and maybe other attributes, such as orientation and extent.
The state x X , where Xis a locally compact, Hausdorff
and second-countable (LCHS) space [6]. The set of targets at
time kis Xk F (X), where F(X)represents the set of
finite subsets of X.
Targets move according to the standard multi-target dynamic
model [6]. Given Xk, each target xXksurvives with
probability pS(x)and moves with a transition density g(· |x),
or disappears with probability 1pS(x). New targets are
born at time step kaccording to an independent Poisson point
process (PPP) with intensity λB
k(·).
A measurement state z∈ Z contains a sensor measurement.
The set Zk∈ F (Z)of measurements at time kis the union of
target-generated measurements and independent clutter mea-
surements, modelled by
Each target xXkgenerates a set of measurements with
density f(·|x).
The set of clutter measurements at each time step has
density c(·).
Given Xk, the measurements generated by different tar-
gets are independent of each other and of the clutter
measurements.
It should be noted that f(·|x)is a general density for
target-generated measurements and we can accommodate any
probabilistic model for target-generated measurements. The
probability that at least one measurement is generated from the
target (effective probability of detection [37]) is 1f(∅|x).
For example, the standard point target model in which a
target xis detected with probability pD(x)and generates a
measurement with density l(·|x)[6], is obtained by
f(Z|x) =
1pD(x)Z=
pD(x)l(z|x)Z={z}
0|Z|>1.
(1)
In the standard extended target model, we can receive more
than one measurement from a target. Specifically, a target xis
detected with probability pD(x)and, if detected, it generates a
PPP measurement with intensity γ(x)l(·|x), where l(·|x)is a
single-measurement density and γ(x)is the expected number
of measurements [20], [38]. It is obtained by
f(Z|x) = (1pD(x) + pD(x)eγ(x)Z=
pD(x)γ|Z|(x)eγ(x)QzZl(z|x)|Z|>0.
(2)
We can also combine both (1) and (2) to model coexisting
point and extended targets, or use any of the probabilistic
extended target models in [20]. In addition, the choice of
f(·|x)can also take into account reflectivity models and the
propagation conditions in the environment [8], [39]–[41].
B. PMBM posterior
We will show in this paper that, for the dynamic and
measurement models in Section II-A, the predicted and pos-
terior densities are PMBMs. That is, given the sequence of
measurements (Z1, ..., Zk), the density fk|k(·)of Xkwith
k∈ {k1, k}is
fk|k(Xk) = X
YW=Xk
fp
k|k(Y)fmbm
k|k(W),(3)
fp
k|k(Xk) = eRλk|k(x)dx Y
xXk
λk|k(x),(4)
fmbm
k|k(Xk) = X
a∈Ak|k
wa
k|kX
nk|k
l=1 Xl=Xk
nk|k
Y
i=1
fi,ai
k|kXi,
(5)
where λk|k(·)is the intensity of the PPP fp
k|k(·), representing
undetected targets, and fmbm
k|k(·)is a multi-Bernoulli mixture
representing targets that have been detected at some point
up to time step k. The sum in (3) is the convolution sum,
which implies that the PPP and MBM are independent [6].
The symbol denotes the disjoint union and the sum is taken
over all mutually disjoint (and possibly empty) sets Yand W
whose union is Xk.
The MBM in (5) has nk|kBernoulli components (potential
targets), each with hi
k|klocal hypotheses. There is a local
hypothesis ain1, ..., hi
k|kofor each Bernoulli i > 0. To
handle arbitrary clutter, we also introduce a local hypothesis
a0n1, ..., h0
k|kofor clutter. Each aiis an index that
associates the i-th Bernoulli, for i0, or the clutter, for
i= 0, to a specific sequence of subsets of the measurement
set, see Section II-C. A global hypothesis is denoted by
a=a0, a1, ..., ank|k∈ Ak|k, where Ak|kis the set of
global hypotheses, see Section II-C. The weight of global
hypothesis ais wa
k|kand meets
wa
k|k
nk|k
Y
i=0
wi,ai
k|k(6)
where wi,ai
k|kis the weight of the i-th Bernoulli compo-
nent, or clutter if i= 0, with local hypothesis ai, and
Pa∈Ak|kwa
k|k= 1. A difference with PMBM filters with
PPP clutter [16], [18], [19] is that global hypotheses and
weights explicitly consider clutter, with index i= 0.
The i-th Bernoulli component with local hypothesis aihas
a density
fi,ai
k|k(X) =
1ri,ai
k|kX=
ri,ai
k|kpi,ai
k|k(x)X={x}
0 otherwise
(7)
where ri,ai
k|kis the probability of existence and pi,ai
k|k(·)is the
single-target density. It should be noted that in this paper
we use the following nomenclature for Bernoulli components,
densities and local hypotheses: Each Bernoulli component,
which is indexed by iand is initiated by a non-empty subset of
measurements at a given time step (see Section III), has hi
k|k
local hypotheses, each with an associated Bernoulli density,
indexed by i, ai. Then, the total number of Bernoulli densities
in (5) across all global hypotheses is Pnk|k
i=1 hi
k|k, and the
number of multi-Bernoulli densities is |Ak|k|, which denotes
the cardinality of Ak|k.
C. Set of global hypotheses
We proceed to describe the set Ak|kof global hypotheses.
We denote the measurement set at time step kas Zk=
z1
k, ..., zmk
k. We refer to measurement zj
kusing the pair
(k, j)and the set of all such measurement pairs up to and
including time step kis denoted by Mk. Then, a local
hypothesis aifor i=0,1, ..., nk|khas an associated set
of measurement pairs denoted as Mi,ai
k⊆ Mk. The set Ak|k
of all global hypotheses meets
Ak|k=na0, a1, ..., ank|k:ain1, ..., hi
k|koi,
nk|k
[
i=0
Mi,ai
k=Mk,Mi,ai
k∩ Mj,aj
k=,i̸=j).
That is, each measurement must be assigned to a local hypoth-
esis, and there cannot be more than one local hypothesis with
the same measurement. In this paper, we construct the (trees
of) local hypotheses recursively, and we allow for more than
one measurement to be associated to the same local hypothesis
at the same time step, i.e., Mi,ai
kmay contain zero, one or
more measurements. At time step zero, the filter is initiated
with n0|0= 0,w0,1
0|0= 1,h0
0|0= 1, and M0,1
0=.
III. GENERAL PMBM FILTER
This section presents the PMBM filter for general target-
generated measurements and arbitrary clutter, with models
described in Section II-A. We consider the standard dynamic
model so the prediction step is the standard PMBM prediction
step [16], [17]. The update is presented in Section III-A. We
provide a discussion and extension of the result to other filter
variants in Sections III-B and III-C. The PMBM for point
targets and arbitrary clutter is explained in Section III-D.
Finally, an analysis of the number of global hypotheses for
different PMBM filters is provided in Section III-E.
A. General PMBM update
Given two real-valued functions a(·)and b(·)on the target
space, we denote their inner product as
a, b=Za(x)b(x)dx. (8)
Then, the update of the predicted PMBM fk|k1(·)with Zk
is given in the following theorem.
Theorem 1. Assume the predicted density fk|k1(·)is a
PMBM of the form (3). Then, the updated density fk|k(·)
with set Zk=z1
k, ..., zmk
kis a PMBM with the following
parameters. The number of Bernoulli components is nk|k=
nk|k1+ 2mk1. The intensity of the PPP is
λk|k(x) = f(∅|x)λk|k1(x).(9)
Let Z1
k, ..., Z2mk1
kbe the non-empty subsets of Zk. The up-
dated number of local clutter hypotheses is h0
k|k= 2mkh0
k|k1
such that a new local clutter hypothesis is included for each
previous local clutter hypothesis and either a misdetection
or an update with a non-empty subset of Zk. The updated
local clutter hypotheses with no clutter at time step k,a0
n1, ..., h0
k|k1o, have parameters M0,a0
k=M0,a0
k1,
w0,a0
k|k=w0,a0
k|k1c().(10)
For a previous local clutter hypothesis ea0n1, ..., h0
k|k1o
in the predicted density, the new local clutter hypothesis
generated by a set Zj
khas a0=ea0+h0
k|k1j,
M0,a0
k=M0,ea0
k1n(k, p) : zp
kZj
ko,(11)
w0,a0
k|k=w0,a0
k|k1cZj
k.(12)
摘要:

1Poissonmulti-Bernoullimixturefilterwithgeneraltarget-generatedmeasurementsandarbitraryclutterÁngelF.García-Fernández,YuxuanXia,LennartSvenssonAbstract—ThispapershowsthatthePoissonmulti-Bernoullimixture(PMBM)densityisamulti-targetconjugatepriorforgeneraltarget-generatedmeasurementdistributionsandarb...

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