Disclosure of Invention
The invention aims to solve the technical problem of providing an active and passive data fusion method, which can overcome the defects of low reliability and large error of a data fusion result caused by the limitation of the existing method to the setting of an angle difference threshold value, reduce the fusion error of active data and passive data and provide the fusion reliability.
The technical scheme adopted by the invention is as follows:
a fuzzy clustering method is used for carrying out data subset division and association membership calculation on time dimension and space dimension according to similarity between active data and passive data.
The specific method comprises the following steps of,
time fusion (1) is carried out on active data and passive data, and data integration is carried out on the active data and the passive data which are acquired in different observation times and scanning periods on a time dimension, wherein the data integration comprises time slice division and time alignment; the time alignment means that the active data and the passive data measurement time are uniformly sequenced in a selected time slice to form active measurement data and passive measurement data with uniformly sequenced measurement time;
acquiring a membership relation table (3), calculating the spatial statistical distance between active data and passive data corresponding to the same measuring time according to the corresponding measuring time based on a fuzzy clustering method, and constructing a fuzzy matrix to acquire the membership relation table;
and (4) performing association fusion on the active data and the passive data according to the membership relation table.
The method also comprises the steps of completing the active data (2), after time fusion, inquiring whether the moment has the measured active data or not according to the uniformly ordered measuring moments, if so, acquiring a membership table based on a fuzzy clustering method, and if not, calculating the active data at the moment.
The specific method for calculating the active data is to complement the active data corresponding to all the passive data measurement moments by means of interpolation or extrapolation according to the fused time sequence.
The time slice division is determined by the motion attribute of specific time, and the faster the target speed is, the shorter the divided time slice is.
The specific method for obtaining the membership table comprises the following steps,
obtaining a distance fuzzy subset of the active data and all the passive data corresponding to the active data at the same measuring moment according to all the passive data corresponding to the active data at the same measuring moment; the distance in the distance fuzzy subset is determined according to the distance square error of the space positions of the active data and the passive data;
selecting at least two membership functions for measurement according to the correlation degree of each distance between the active data and the passive data;
substituting each distance value in the distance fuzzy subset into the membership function to obtain a three-dimensional fuzzy matrix;
and weighting each membership degree corresponding to the same distance value in the three-dimensional fuzzy matrix, multiplying each membership degree by the corresponding weight value, and adding to obtain the membership relation of the distance values, thereby obtaining a membership relation table of active data and passive data.
The method also comprises the steps of refining the data of the fused result by utilizing the redundancy and complementarity between the active data and the passive data, counting the correlation between the fused results within a period of time, and giving a corresponding weight value, wherein the larger the correlation is, the larger the weight value is, and otherwise, the weight value is reduced.
And according to the correlation degree of each distance between the active data and the passive data, the membership function comprises four membership functions of good membership function, medium membership function and fair membership function.
The weights of four membership degrees of good, medium and fair which correspond to the same distance value in the three-dimensional fuzzy matrix are respectively 0.4, 0.3, 0.2 and 0.1.
Compared with the prior art, the invention has the beneficial effects that:
compared with the prior art that the quality of the fusion result depends on the selection of the threshold value threshold of the angle difference, the method adopts a space-time dimension fuzzy clustering based method, judges the fusion relation between the active data and the passive data through the membership degree relation table, does not need to set a special fusion threshold any more, and is more flexible to use.
The invention adopts fuzzy clustering method to obtain the membership degree association table of the active data and the passive data, associates according to the membership degree association table, gives certain weight to the association result, and updates the weight according to the long-time fusion result, thereby greatly improving the fusion reliability and reducing the fusion error.
The method is suitable for all active/passive data fusion systems, is also suitable for data fusion systems of various sensors and has good system applicability.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Any feature disclosed in this specification (including any accompanying drawings) may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. That is, unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features.
A fuzzy clustering method is used for carrying out data subset division and association membership calculation on time dimension and space dimension according to similarity between active data and passive data.
Compared with the prior art, the method has the advantages that a special angle difference threshold value does not need to be set, the fusion result has higher reliability, and the fusion error is greatly reduced.
The specific method comprises the following steps of,
as shown in fig. 1, time fusion is performed on active data and passive data (1), and data integration is performed on the active data and the passive data acquired in different observation times and scanning periods in a time dimension, including time slice division and time alignment; the time alignment means that the active data and the passive data measurement time are uniformly sequenced in a selected time slice to form active measurement data and passive measurement data with uniformly sequenced measurement time;
acquiring a membership relation table (3), calculating the spatial statistical distance between active data and passive data corresponding to the same measuring time according to the corresponding measuring time based on a fuzzy clustering method, and constructing a fuzzy matrix to acquire the membership relation table;
and (4) performing association fusion on the active data and the passive data according to the membership relation table.
The method also comprises the steps of completing the active data (2), after time fusion, inquiring whether the moment has the measured active data or not according to the uniformly ordered measuring moments, if so, acquiring a membership table based on a fuzzy clustering method, and if not, calculating the active data at the moment.
As an embodiment, the specific method for estimating the active data is to complement the active data corresponding to all the passive data measurement times by interpolation or extrapolation according to the fused time series.
Since the data rate of the passive data acquisition is higher than that of the active data, all the active data corresponding to the passive data measurement time need to be calculated for the convenience of subsequent fusion. During specific operation, according to the fused measurement time of unified sequencing, active data are screened and supplemented according to the passive measurement time: if the active data exists at the corresponding passive measurement time, continuing the subsequent operation, otherwise, completing the active data corresponding to the passive measurement time according to an interpolation or extrapolation mode.
And when no active measurement data exists at the corresponding passive measurement moment, performing active data completion by adopting an interpolation or extrapolation method. And during interpolation or extrapolation, a method for constructing an approximation function by adopting curve fitting is adopted, wherein the approximation function is set as y ═ f (t), t is the passive data measurement time, and y is the active data corresponding to the passive data measurement time. The concrete formula of the approximation function is as follows:
wherein, t0、t1、t2Time instant, y, at which there is active measurement data for the time instant close to the passive data measurement instant0=f(t0)、y1=f(t1)、y2=f(t2) Are each t0、t1、t2Corresponding active metrology data, i.e. t0、t1、t2、y0、y1、y2Are all known quantities. Using t0、t1、t2Time value and its corresponding function value y0、y1、y2The second order polynomial coefficient of the approximation function y ═ f (t) can be determined and substituted into the passive measurement time value t to be interpolated or extrapolated, so that the active data corresponding to the passive measurement time can be further calculated.
The time slice division is determined by the motion attribute of specific time, the faster the target speed is, the shorter the divided time slice is, for example, the still/low speed target can select the fusion time slice to be minute, and the high speed target can select the fusion time slice to be second.
The specific method for obtaining the membership table comprises the following steps,
obtaining a distance fuzzy subset of the active data and all the passive data corresponding to the active data at the same measuring moment according to all the passive data corresponding to the active data at the same measuring moment; the distance in the distance fuzzy subset is determined according to the distance square error of the space positions of the active data and the passive data;
selecting at least two membership functions for measurement according to the correlation degree of each distance between the active data and the passive data;
substituting each distance value in the distance fuzzy subset into the membership function to obtain a three-dimensional fuzzy matrix;
and weighting each membership degree corresponding to the same distance value in the three-dimensional fuzzy matrix, multiplying each membership degree by the corresponding weight value, and adding to obtain the membership relation of the distance values, thereby obtaining a membership relation table of active data and passive data.
The method also comprises the steps of refining the data of the fused result by utilizing the redundancy and complementarity between the active data and the passive data, counting the correlation between the fused results within a period of time, and giving a corresponding weight value, wherein the larger the correlation is, the larger the weight value is, and otherwise, the weight value is reduced. And reducing the influence caused by error association according to the long-time fusion result and the weight value result, thereby obtaining a more accurate active data and passive data fusion result.
If the active data corresponding to the measurement time is Pi(i-1, …, N) corresponding to passive data being Qj(j-1, …, M), one active data P is takeniIt forms a finite fuzzy subset R ═ with respect to the statistical distance R (R) for all passive data at that momenti1,ri2,…,riM). The statistical distance r is determined according to the distance square difference of the space positions of the active data and the passive data; i is active data PiThe number of a certain active data; j is a certain passive data Q in the passive datajThe number of (2).
As a specific embodiment, the degree of correlation for each distance between active data and passive dataSelecting four membership functions u of good, medium, fair and poor1、u2、u3、u4The metric is performed and the membership function is expressed as follows.
in the above formula, w1, w2 and w3 are adjustment parameters, and are specifically determined according to the calculation range of the statistical distance r between the active data and the passive data, and four regions [0, w1], [ w1, w2], [ w2, w3], [ w3 and infinity ] of the statistical distance r divided by the adjustment parameters w1, w2 and w3 respectively correspond to four association degrees of good, medium, possible and poor distance association.
Substituting each distance value in the fuzzy subset R into the membership function u1、u2、u3、u4And obtaining a three-dimensional fuzzy matrix with one dimension of NxMx4.
For the same statistical distance r in the fuzzy matrixijThe corresponding 4 membership degrees are weighted according to good, medium, right and difference, and are sequentially taken as 0.4, 0.3, 0.2 and 0.1, and the statistical distance r is obtained by multiplicationijCorresponding membership cij=0.4*u1(rij)+0.3*u2(rij)+0.2*u3(rij)+0.1*u4(rij) Obtaining the membership degree relation table C of the active data and the passive data (C ═ C)ij)N×MThe membership degree relation table is a two-dimensional matrix with dimension NxM, and reflects the correlation condition of active data and passive data.