CN107886058B - Noise-related two-stage volume Kalman filtering estimation method and system - Google Patents
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Abstract
The invention discloses a noise-related two-stage volume Kalman filtering estimation method and a system, wherein a noise-related system is transformed by adopting an identity deformation method to establish a system model; converting the system model from a noise-related system to a noise-unrelated system by adding a coefficient, and establishing a new system model; and then, carrying out recursive calculation on the noise parameters in the new system model and the two-stage filtering to obtain a noise-related two-stage volume Kalman filtering estimator. The two-stage volume information filtering algorithm related to noise provided by the invention eliminates a Jacobian matrix by utilizing the approximate relation between the product of cross covariance and error covariance and the Jacobian matrix, and ensures the application of the algorithm in a high-dimensional nonlinear system.
Description
Technical Field
The present invention relates to the field, and in particular, to a noise-dependent two-stage volumetric Kalman filter estimation method and system.
Background
The precondition of various two-stage filtering algorithms derived at present is that a nonlinear Gaussian system is assumed to be noise-independent, that is, state equation noise and measurement equation noise are not related and are Gaussian white noise, which is the noise condition under an ideal state. In practical application, however, the noise correlation of the system generally exists, for example, the noise correlation occurs due to the dual influence of the internal components of the system and the external environment change; the system for measuring the colored noise is subjected to noise dimension expansion, and the original system can be converted into a noise related system after the system is expanded into a state; in systems requiring multi-sensor information fusion, such as moving target tracking, there are also a lot of noise-related situations. For noise correlation systems, the conventional solution is to ignore the correlated noise and use conventional two-stage volumetric Kalman filtering to estimate, which inevitably reduces the estimation accuracy. According to the scheme, the conversion coefficient matrix is introduced, the noise-related system is converted into the uncorrelated system, the conversion relation between the uncorrelated system and the uncorrelated system is obtained, estimation is carried out, the related noise is fully considered, and accurate tracking of the noise-related system is achieved.
The pure azimuth tracking system tracks the state of a moving target through two sensors to obtain nonlinear measured values, each sensor can only obtain an angle observation value of the target state, and the two angle observation values are marked as alphai,kAnd betai,kThe observations of the two angles form the position of the intersection in the plane coordinates. For two sensors S of a rectangular coordinate systemi1And Si2(i-1, 2, …, N) are fixed to the stage P, respectively1And P2And the distance between them is d. With a plurality of sensors fixed to the platform Pj(j { (S) } at (1, 2)1,j,Pj),(S2,j,Pj),…,(SN,j,Pj) Corresponding to a non-linear measurement value of { (α)1,k,β1,k),(α2,k,β2,k),…,(αN,k,βN,k)}。
The kinetic model is a four-dimensional nonlinear system, xk=[x1,k x2,k y1,k y2,k]T, wherein x1,kAnd x2,kIs the displacement component in the east and north directions, y1,kAnd y2,kIs the velocity component relative to the displacement component, taking the movement of the target as the CV model, the equation of state and the variance of the deviation are as follows:
Observing the function according to the cross principle
In a multi-sensor system, the measurement equation is:
wherein h is1,k(xk)=h2,k(xk)=…=hN,k(xk)=hk(xk)。
the simulation time was 200 seconds, and 1000 Monte Carlo simulations were performed for both algorithms. The algorithm error is calculated using the root mean square error (RMSE error) as follows:
wherein M is the Monte Carlo number of times,andrespectively represent x under the nth Monte Carlo simulation*State values and estimated values of.
In summary, the problems of the prior art are as follows: in the prior art, correlated noise is not analyzed, so that the estimation precision is reduced; the tracking result is poor; correlated noise is not considered in the estimation process, the correlated noise is considered according to the condition of the irrelevant noise, and the difficulty of the solution is that the correlated noise cannot be considered while the position of the aircraft is estimated; the filtering divergence phenomenon occurs, and further tracking estimation can not be carried out at all.
Disclosure of Invention
In order to solve the problems of the prior art, the embodiment of the invention provides a method. The invention can be used in the field of target tracking of single or multiple aircrafts, and is particularly explained by taking a pure azimuth tracking system as an example.
The invention is realized in such a way that a noise-related two-stage volume Kalman filtering estimation method comprises the following steps:
transforming the noise-related system by adopting an identity deformation method, and establishing a system model;
converting the system model from a noise-related system to a noise-unrelated system by adding a coefficient, and establishing a new system model;
and then, carrying out recursive calculation on the noise parameters in the new system model and the two-stage filtering to obtain a noise-related two-stage volume Kalman filtering estimator.
Further, the step of transforming the noise-related system by using the method of constant deformation and establishing the system model is specifically as follows:
the noise correlation system is a nonlinear gaussian system:
xk+1=fk(xk)+ωk+1,k; (1)
zk=hk(xk)+υk; (2)
where k is a discrete time series, xk∈Rn×1Is the state vector of the system, zk∈Rm×1Is a measurement vector, f (-) and h (-) are known nonlinear state transfer functions and measurement functions and are in xkProcess noise sequence omega of continuous micro processk+1,kAnd measuring the noise sequence upsilonkAre Gaussian white noise sequences with the mean value E (omega)k+1,k)=qk,E(υk)=rkVariance Qk+1,kAnd RkThe following conditions are satisfied:
initial statex0And omegak+1,k、υkIrrelevant, and satisfy:
further, the step of converting the system model from a noise-related system to a noise-unrelated system by adding a coefficient to establish a new system model specifically comprises:
converting the noise-related system into an uncorrelated system through constant deformation, and then performing filtering estimation;
from the model equation (2):
zk-hk(xk)-υk=0;
let ΔkThe undetermined coefficients are as follows:
Δk(zk-hk(xk)-υk)=0 (3);
substituting the formula (1) and finishing to obtain:
wherein
Fk(xk)=fk(xk)+Δk(zk-hk(xk)) (5);
The models shown in equations (1) and (2) are converted into:
zk=hk(xk)+υk (8);
Converting a noise-related system to a noise-independent system, there are:
unfolding to obtain:
when equation (9) is satisfied, the noise-independent system process noise and the metrology noise are uncorrelated;
using a conversion model method to obtain a noise-related nonlinear Gaussian filter formula, and performing equal angular notation t expression;
further, the step of obtaining a noise-related two-stage volume Kalman filter estimator by using the recursive calculation of the noise parameter and the two-stage filtering in the new system model specifically comprises:
non-linear gaussian system with random bias:
where k is a discrete time series, xk∈Rn×1Is the state vector of the system, bk∈Rp×1Is the systematic deviation vector, zk∈Rm×1Is a measurement vector, fk(. and h)k(. is) a known nonlinear state transfer function and metrology function at xkProcess noise sequenceOffset noise sequenceAnd measuring the noise sequence upsilonkAre Gaussian white noise sequences, the deviation noise is uncorrelated with the process noise and the measurement noise, wherein the average value isE(υk)=rkVariance of And RkThe following conditions are satisfied:
initial state x0、b0And omegak+1,k、υkIrrelevant, and satisfy:
order to
Hk(Xk)=hk(xk)+Fkbk;
The system model given by equation (15) is rewritten as follows:
Xk+1=Γk(Xk)+ωk
Zk=Hk(Xk)+υk
Based on the identity transform, the model (15) becomes a noise-independent system as shown in equations (7) and (8), as shown in equation (17):
Initializing state conditions:
for k=1,2,…,N do;
step one, time updating:
1) assuming a posteriori density function at known k-1 timeTo Pk-1|k-1Cholesky decomposition is carried out to obtain
3) Let mk-1=qk-1-ΔkrkM is scaled according to the state vector dimension and the deviation vector dimensionkPartitioning is carried out, and then:
same pair rkThe partitioning is carried out as follows:
by mk-1Estimating noise dependent unbiased filter state prediction values
Sum biased filter state prediction
4) Order to
According to the dimension of the block matrix in the two-stage transformation formula, the method comprises the following steps ofPartitioning:
by means of coupling relationshipsEstimating noise-dependent unbiased filter state error covarianceSum-biased filter state error covariance
Step two, measurement updating:
B) Calculating volume pointsAnd propagation volume points propagated through the measurement equationWherein, i is 1, 2.. times, m;
E) Will be a formulaPartitioning according to corresponding dimensionality to obtain a partitioning gain matrix:
F) By mk-1And rkComputing noise-dependent unbiased filter state estimate
State estimation of a biased filter in relation to noise
And (6) ending.
It is another object of the present invention to provide a noise-dependent two-stage volumetric Kalman filter estimation system.
The technical scheme provided by the embodiment of the invention has the following beneficial effects: the invention provides a noise-related Two-stage volume Kalman filtering algorithm (Two-stage volume tube Filter with corrected noise, TSC KF-CN), which provides a Two-stage volume Kalman filtering algorithm of a transformation model based on a minimum variance estimation criterion, and converts a noise-related system into an uncorrelated system and obtains a conversion relation between the Two by introducing a conversion coefficient matrix.
In practical applications, noise-dependent nonlinear systems are very common, and if the correlated noise is not considered, the accuracy of the estimation is necessarily reduced by still applying the conventional two-stage filtering algorithm. The invention provides a two-stage volume Kalman filtering algorithm of a transformation model based on a minimum variance estimation criterion, a conversion coefficient matrix is introduced, a noise correlation system is converted into an uncorrelated system and a conversion relation between the uncorrelated system and the uncorrelated system is obtained, in practical application, the noise correlation is taken into consideration as a condition, the method is used in the field of target tracking of single or multiple aircrafts, the tracking precision is superior to the condition of neglecting noise correlation and counting, and a better tracking result is obtained.
In a noise-related nonlinear system, the estimated value of each time position of the TSCKF-CN algorithm is superior to a two-stage volume Kalman algorithm without considering the related noise, the estimation precision advantage is obvious, and in some times, the two-stage volume Kalman filtering does not consider the related noise, so that the filtering divergence phenomenon occurs, and further tracking estimation cannot be carried out at all.
Drawings
Fig. 1 is a flowchart of a noise-dependent two-stage volumetric Kalman filter estimation method according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
In the prior art, correlated noise is not analyzed, so that the estimation precision is reduced; the tracking result is poor.
The present invention will be described in detail below with reference to the accompanying drawings.
As shown in fig. 1, the method for estimating a noise-related two-stage volume Kalman filter according to an embodiment of the present invention includes:
s101: transforming the noise-related system by adopting an identity deformation method, and establishing a system model;
s102: converting the system model from a noise-related system to a noise-unrelated system by adding a coefficient, and establishing a new system model;
s103: and then, carrying out recursive calculation on the noise parameters in the new system model and the two-stage filtering to obtain a noise-related two-stage volume Kalman filtering estimator.
The invention is further described with reference to specific examples.
Optionally, the step of transforming the noise-related system by using the method of identity deformation and establishing a system model specifically includes:
consider the following nonlinear gaussian system:
xk+1=fk(xk)+ωk+1,k (4-1)
zk=hk(xk)+υk (4-2)
where k is a discrete time series and where,is the state vector of the system and,is a measurement vector, f (-) and h (-) are known nonlinear state transfer functions and measurement functions and are in xkProcess noise sequence omega of continuous micro processk+1,kAnd measuring the noise sequence upsilonkAre Gaussian white noise sequences with the mean value E (omega)k+1,k)=qk,E(υk)=rkVariance Qk+1,kAnd RkThe following conditions are satisfied:
initial state x0And omegak+1,k、υkIrrelevant, and satisfy:
optionally, the step of adding a coefficient to convert the system model from a noise-related system to a noise-unrelated system, and the step of establishing a new system model specifically includes:
and transforming the model, converting the noise-related system into an uncorrelated system through constant deformation, and then performing filtering estimation.
From the model equation (4-2), it can be derived:
zk-hk(xk)-υk=0
let ΔkThe undetermined coefficients are as follows:
Δk(zk-hk(xk)-υk)=0 (4-3)
substituting into equation (4-1) and working up gives:
wherein
Fk(xk)=fk(xk)+Δk(zk-hk(xk)) (4-5);
The models shown in equations (4-1) and (4-2) are converted into:
zk=hk(xk)+υk (4-8);
Converting the model from a noise-related system to a noise-independent system, i.e. making the system process noise uncorrelated with the measurement noise, then:
unfolding to obtain:
namely, when the formula (4-9) is satisfied, the process noise and the measurement noise in the system model are not related any more, a nonlinear Gaussian filter algorithm can be used for calculation, and in order to distinguish the nonlinear Gaussian filter formula, the noise-related nonlinear Gaussian filter formula obtained by using a conversion model method is represented by a corner mark t.
The invention provides a noise-related Two-stage volume Information filtering estimation algorithm (TSCIF-CN), which eliminates a Jacobian matrix by utilizing the product of cross covariance and error covariance and the approximate relation of the Jacobian matrix, and ensures the application of the algorithm in a high-dimensional nonlinear system.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (2)
1. A noise-correlated two-stage volumetric Kalman filter estimation method, operating in a pure azimuth tracking system onboard in target tracking of a single or multiple aircraft, the noise-correlated two-stage volumetric Kalman filter estimation method comprising:
transforming the noise-related system by adopting an identity deformation method, and establishing a system model;
converting the system model from a noise-related system to a noise-unrelated system by adding a coefficient, and establishing a new system model;
then, the recursive calculation of the noise parameters in the new system model and the two-stage filtering is carried out to obtain a two-stage volume Kalman filtering estimator related to the noise;
the steps of adopting the method of constant deformation to transform the noise-related system and establishing the system model are as follows:
the noise correlation system is a nonlinear gaussian system:
xk+1=fk(xk)+ωk+1,k; (1)
zk=hk(xk)+υk; (2)
where k is a discrete time series, xk∈Rn×1Is the state vector of the system, zk∈Rm×1Is a measurement vector, f (-) and h (-) are known nonlinear state transfer functions and measurement functions and are in xkProcess noise sequence omega of continuous micro processk+1,kAnd measuring the noise sequence upsilonkAre Gaussian white noise sequences with the mean value E (omega)k+1,k)=qk,E(vk)=rkVariance Qk+1,kAnd RkThe following conditions are satisfied:
initial state x0And omegak+1,k、υkIrrelevant, and satisfy:
the step of converting the system model from a noise-related system to a noise-unrelated system by adding the coefficient to establish a new system model specifically comprises the following steps:
converting the noise-related system into an uncorrelated system through constant deformation, and then performing filtering estimation;
from the model equation (2):
zk-hk(xk)-υk=0;
let ΔkThe undetermined coefficients are as follows:
Δk(zk-hk(xk)-vk)=0 (3);
substituting the formula (1) and finishing to obtain:
wherein
Fk(xk)=fk(xk)+Δk(zk-hk(xk)) (5);
The models shown in equations (1) and (2) are converted into:
zk=hk(xk)+υk (8);
Converting a noise-related system to a noise-independent system, there are:
unfolding to obtain:
when equation (9) is satisfied, the noise-independent system process noise and the metrology noise are uncorrelated;
using a conversion model method to obtain a noise-related nonlinear Gaussian filter formula, and performing equal angular notation t expression;
then, the recursive calculation of the noise parameter and the two-stage filtering in the new system model is used to obtain a noise-related two-stage volume Kalman filtering estimator, which comprises the following steps:
step one, time updating:
1) assuming a posteriori density function at known k-1 timeTo Pk-1|k-1Cholesky decomposition is carried out to obtain
3) Let mk-1=qk-1-ΔkrkM is scaled according to the state vector dimension and the deviation vector dimensionkPartitioning is carried out, and then:
same pair rkThe partitioning is carried out as follows:
by mk-1Estimating noise dependent unbiased filter state prediction values
Sum biased filter state prediction
4) Order to
According to the dimension of the block matrix in the two-stage transformation formula, the method comprises the following steps ofPartitioning:
by means of coupling relationshipsEstimating noise-dependent unbiased filter state error covarianceSum-biased filter state error covariance
Step two, measurement updating:
B) Calculating volume pointsAnd propagation volume points propagated through the measurement equationWherein, i is 1, 2.. times, m;
E) Will be a formulaPartitioning according to corresponding dimensionality to obtain a partitioning gain matrix:
F) By mk-1And rkComputing noise-dependent unbiased filter state estimate
State estimation of a biased filter in relation to noise
Noise-dependent biased filter estimation error covariance
2. A noise-correlated two-stage volumetric Kalman filter estimation system of the noise-correlated two-stage volumetric Kalman filter estimation method according to claim 1.
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