Detailed Description
According to the environmental characteristics and the working characteristics of the navigation system, the invention combines the output information of navigation sensors with different working characteristics to form the integrated navigation system based on multi-source information fusion on the basis of an inertia/satellite integrated navigation system with mature technology and unique advantages, thereby overcoming the service defects and insufficient capability caused by the inherent vulnerability of the GNSS, improving the precision of the whole navigation system and leading the navigation system to be capable of accurately and reliably completing tasks for a long time.
The invention relates to a vector distribution-based self-adaptive multi-source fusion navigation method, which comprises the following steps of:
step 1: selecting a northeast coordinate system as a navigation system, selecting 18-dimensional system errors as state quantities, establishing a federal filtering combined navigation model according to the output characteristics of each sensor, and designing a federal filter;
step 2: designing a method for fault detection and isolation through vector distribution, and detecting and isolating information of fault dimensions of each sensor;
and step 3: and constructing vector distribution coefficients for each dimension of information of each sub-filter by using the output result of each sub-filter, and performing information fusion in the main filter to obtain a global optimal estimation result.
Further, in the step 1, a northeast coordinate system is selected as a navigation system, 18-dimensional system errors are selected as state quantities, a federal filtering combined navigation model is established according to the output characteristics of each sensor, and a federal filter is designed, specifically as follows:
(2.1) firstly, establishing a federal filtering integrated navigation system model under a navigation coordinate system; the error model of the inertial navigation system adopts a universal error model, the public error reference system selects an inertial navigation system, the navigation coordinate system selects a northeast geographic coordinate system, and the state vector X of the system is
Wherein
The attitude angle error in the northeast direction; delta V
E、δV
N、δV
UIs the speed error in the northeast direction; δ L, δ λ, δ H are position errors in the weft height direction; epsilon
bx、ε
by、ε
bzRandom drift of the gyroscope in three axial directions; epsilon
rx、ε
ry、ε
rzRandom noise is generated in a first-order Markov process of the gyroscope in three axial directions;
is a constant deviation of the accelerometer in three axial directions;
equation of state of system
Comprises the following steps:
wherein F (t) is a state transition matrix of the system, G (t) is an error coefficient matrix, and W (t) is a white noise random error vector, and the specific form is as follows:
state transition matrix f (t):
in the formula FNIs a systematic error matrix, FsError transformation matrix for inertial devices, FMThe noise matrix of the inertial device is as follows:
wherein
An attitude transformation matrix;
wherein, TgRepresenting the relevant time of the gyro, TaRepresenting the relevant time of the accelerometer, and x, y and z respectively representing the three-axis directions of the carrier system;
the error coefficient matrix g (t) is:
the white noise random error vector W (t) is:
W(t)=[wgx wgy wgz wrx wry wrz wax way waz]T (8)
wherein, wgRepresenting white noise of the gyro, wrRepresenting March white noise, waRepresenting accelerometer white noise;
the measurement equation Z (t) of the system is:
Z(t)=H(t)X(t)+V(t) (9)
where x (t) is the state vector of the system, v (t) ═ NE NN NU]TFor measuring noise, NE、NN、NUThe measurement noise in the direction, H (t), is the measurement matrix of the system, and is selected differently according to different sub-filters; since a continuous system model is not easily realized in a computer, it is necessary to discretize the system model and discretize the state equation (2) and the measurement equation (9) to obtain a system model
Wherein, XkIs the state vector at time k, phik|k-1For the system one-step transfer matrix, Γ, from time k-1 to time kk-1Is a noise matrix of the system, which characterizes that each system noise from k-1 to k time respectively influences the brightness of each state at k time, Wk-1System noise at time k-1, ZkIs the measurement vector at time k, HkIs a measurement matrix at time k, VkMeasurement noise at time k
In the formula
Where T is the iteration period, TkIs the k moment;
(2.2) design of a federal filter:
each sub-filter adopts a Kalman filtering mode, and the method specifically comprises the following steps:
one-step prediction equation of state:
in the formula (I), the compound is shown in the specification,
is to utilize
Calculating to obtain X
kThe one-step prediction is carried out;
the state estimation equation:
is predicted in one step
Based on the measured value, the true value X is measured
kIs estimated, where K
kIs the filter gain;
kalman gain equation:
in the formula, Pk|k-1Predicting the mean square error for one step; rkA variance matrix for the measured noise;
one-step prediction mean square error equation:
mean square error estimation equation:
in the formula, P
k|kTo estimate the value
The estimated mean square error equation of (a);
the position information representing the inertial navigation system is
In the formula ofI、LI、HIAs a measure of latitude, longitude, altitude, λ, of the inertial navigation systemt、Lt、HtThe latitude, longitude and altitude of the vehicle-mounted device are true values, and the delta lambda, delta L and delta H are measurement error values of the latitude, longitude and altitude of the inertial navigation system;
the velocity information representing the inertial navigation system is
In the formula vIN、vIE、vIUIs a measure of the velocity of the inertial navigation system in the northeast direction, vN、vE、vUIs the true value of the speed of the vehicle-mounted device in the northeast direction, delta vN、δvE、δvUMeasuring error value of the velocity of the inertial navigation system in the northeast direction;
the position information of the satellite navigation system is
In the formula ofG、LG、HGAs a measure of the satellite navigation system latitude, longitude, altitude, lambdat、Lt、HtIs the true value of latitude, longitude and altitude of the vehicle-mounted device, NE、NN、NUMeasuring error values of the satellite navigation system in the northeast direction;
the velocity information representing the satellite navigation system is
In the formula vGE、vGN、vGUAs a measure of the velocity of the satellite navigation system in the northeast direction, vN、vE、vUIs the true value of the speed of the vehicle-mounted device in the northeast direction, MN、ME、MUMeasuring error value of the velocity of the inertial navigation system in the northeast direction; the position measurement value N and the speed measurement value M are converted in order to be matched with the longitude and latitude dimensions of the inertial navigation system;
the speed information indicating the odometer is
In the formula vOE、vON、vOUAs a measure of the velocity of the odometer in the northeast direction, vN、vE、vUIs the true value of the speed of the vehicle-mounted device in the northeast direction, ON、OE、OUThe measurement error value of the speed of the odometer in the northeast direction is shown;
the altitude information indicating the altimeter is
Ha=HU-A (23)
In the formula HaAs a measure of the height of the altimeter, HUThe altitude measurement error value A is a true value of the position of the vehicle-mounted device in the vertical direction, and A is a measurement error value of the altimeter in the altitude;
(2.2.1) design of SINS/BDS sub-filter
From (2.1), the equation of state of the SINS/BDS sub-filter is known as
Measuring method of SINS/BDS sub-filter
Wherein
VG(t)=[NN NE NU ME MN MU]T (27)
The measured noise is treated as white noise, and its variance is respectively
R
M、R
NThe long radius and the short radius of the earth, respectively;
(2.2.2) design of SINS/odometer sub-filter
According to (2.1), the state equation of the SINS/BDS sub-filter is
The measurement equation of the SINS/odometer sub-filter is as follows
Wherein
HO(t)=[03×3 diag[1 1 1] 03×12] (30)
VG(t)=[OE ON OU]T (31)
Measuring the white noise with the average value of 0;
(2.2.3) design of Federal Filter Main Filter
The federal filter is a two-stage filter structure, and the output X of a common reference subsystem (SINS)kOn the one hand, the main filter and on the other hand, each sub-filter is used as a measurement value; the outputs of the sub-systems being supplied only to the respective filters, the local estimated values X of the sub-filtersiAnd its covariance matrix PiInto the main filter and the mainFusing the estimated values of the filters together to obtain a global estimated value;
global optimum estimation synthesized by main filter and sub-filter
And its corresponding covariance matrix P
gIs amplified into
And then feeding back to the sub-filter to reset the estimation value of the sub-filter, namely:
the main filter has a covariance matrix of
β
iDetermining according to an information distribution principle;
the invention comprehensively considers the filtering precision and the structural performance of the system, and designs a self-adaptive information fusion method based on vector distribution from the covariance matrix of the system and the observability of the system, and the method is described in detail in claim 4.
Further, the step 2 designs a method for detecting and isolating faults through vector distribution, and detects and isolates information of fault dimensions of each sensor, specifically as follows:
(3.1) sub-filter time update:
wherein i represents the ith sub-filter;
(3.2) fault diagnosis:
the following fault diagnosis functions are first constructed:
Λi,k=ri,k(ri,k)T[Hi,kPi,k|k-1(Hi,k)T+Ri,k]-1 (33)
wherein r isi,kRepresenting the residual of system i at time k, Λi,kIs a matrix of m rows and m columns, which can be expressed as:
when no fault occurs in the sub-filter, Λi,kEach element on the diagonal in the array should obey x with degree of freedom of 12Distribution, when a sensor in the system fails, the fault is not satisfied any more, a proper threshold value is set at the moment, and the following judgment rule is established:
defining the measured noise coefficient B of the ith sub-filteri,kComprises the following steps:
wherein
By obtaining a measured noise figure B
i,kReconstructing the measured noise matrix
In equation (37), when a dimension of the measurement information is determined to be normal, B
i,kCorresponding opposite angleThe line element is set to 1, otherwise to 0, thus reconstructing the metric noise matrix in equation (39)
For normal measurement variables, the corresponding noise variance after adjustment is unchanged; for the fault measurement variable, the adjusted corresponding noise variance tends to be infinite, so that the dimension information of the sensor fault is dynamically isolated;
(3.3) sub-filter measurement update
And after the sub-filters perform measurement updating, transmitting the filtering result of the fault dimension information of the isolation sensor to the main filter for the next step of information fusion.
Further, in step 3, vector distribution coefficients are constructed for each dimension of information of each sub-filter by using output results of each sub-filter, and information fusion is performed in the main filter to obtain a global optimal estimation result, which is specifically as follows:
covariance matrix P of sub-filtersi,k|kThe estimation precision of the sub-filters can be reflected, and the structural performance of the system can be reflected by the observability of the system; the conventional adaptive information allocation method uses trace (P)i,k|k) Calculating information distribution coefficients, but in the actual federal filtering model, each sub-filter generally contains more than one measured variable, and even in the same filter, each measured variable has different estimation precision; the invention designs a self-adaptive information distribution coefficient algorithm based on vector distribution based on the covariance matrix of the sub-filters and the observability of the system;
first, a sub-filter covariance matrix Pi,k|kAnd (3) carrying out characteristic value decomposition:
Pi,k|k=Di,kΛi,k(Di,k)T (41)
in the formula
Wherein λn,i,kIs the ith sub-filter covariance matrix Pi,k|kN characteristic value of (D)i,kIs an orthogonal matrix resulting from eigenvalue decomposition; defining a distribution coefficient matrix Ai,kComprises the following steps:
in the formula
Ai,kSatisfy the theorem of information conservation
The partition coefficient matrix C is constructed by the observability of the sub-filtersi,kLet us assume that the observability matrix of the sub-filter i is Qi,kTo Q, pairi,kPerforming singular value decomposition
Qi,k=Ui,kSi,k(Vi,k)T (46)
Wherein U isi,kAnd Vi,kIs an orthogonal matrix, Si,kThe method specifically comprises the following steps:
wherein Λr×r=diag{σ1,i,k,σ2,i,k…σri,i,k},σn,i,k(n=1,2,…ri),riAre respectively Qi,kSingular value and rank of;
then measure the coefficient Ci,kIs defined as:
wherein
Ci,kSatisfy the theorem of information conservation
Then the vector-based information assigns coefficient Bi,kComprises the following steps:
at the moment, the information distribution coefficient still meets the information conservation principle:
the asymmetry of the error covariance matrix of the system can destroy the consistent convergence stability of the Kalman filter, increase the filtering error and even lose the filtering effect; in order to ensure the symmetry of the error covariance matrix, the information distribution mode is as follows:
the invention is described in further detail below with reference to the figures and the embodiments.
Examples
With reference to fig. 1, the present invention is a vector distribution-based adaptive multi-source fusion navigation method, which includes the following steps:
step 1: selecting a northeast coordinate system as a navigation system, selecting 18-dimensional system errors as state quantities, establishing a federal filtering combined navigation model according to the output characteristics of each sensor, and designing a federal filter;
with reference to fig. 2, in the federation kalman filter of the present invention, 3 navigation information sources are used, so an SINS/GNSS, an SINS/odometer sub-filter, and a main filter for information fusion are adopted, information is distributed between each sub-filter and the main filter by using the information distribution principle, each sub-filter processes the respective measurement information and obtains a local estimate, and then information fusion is performed in the main filter to obtain an optimal estimate.
(1.1) firstly, establishing a federal filtering integrated navigation system model under a navigation coordinate system; the error model of the inertial navigation system adopts a universal error model, the public error reference system selects an inertial navigation system, the navigation coordinate system selects a northeast geographic coordinate system, and the state vector X of the system is
Wherein
The attitude angle error in the northeast direction; delta V
E、δV
N、δV
UIs the speed error in the northeast direction; δ L, δ λ, δ H are position errors in the weft height direction; epsilon
bx、ε
by、ε
bzRandom drift of the gyroscope in three axial directions; epsilon
rx、ε
ry、ε
rzRandom noise is generated in a first-order Markov process of the gyroscope in three axial directions;
is a constant deviation of the accelerometer in three axial directions;
equation of state of system
Comprises the following steps:
wherein F (t) is a state transition matrix of the system, G (t) is an error coefficient matrix, and W (t) is a white noise random error vector, and the specific form is as follows:
state transition matrix f (t):
in the formula FNIs a systematic error matrix, FsError transformation matrix for inertial devices, FMThe noise matrix of the inertial device is as follows:
wherein
An attitude transformation matrix;
wherein, TgRepresenting the relevant time of the gyro, TaThe relevant time of the accelerometer is shown, and x, y and z respectively show the three-axis directions of the carrier system.
The error coefficient matrix g (t) is:
the white noise random error vector W (t) is:
W(t)=[wgx wgy wgz wrx wry wrz wax way waz]T (1.8)
wherein, wgRepresenting white noise of the gyro, wrRepresenting March white noise, waRepresenting accelerometer white noise.
The measurement equation Z (t) of the system is:
Z(t)=H(t)X(t)+V(t) (1.9)
where x (t) is the state vector of the system, v (t) ═ NE NN NU]TFor measuring noise, NE、NN、NUThe measurement noise in the direction, H (t), is the measurement matrix of the system, and is selected differently according to different sub-filters; since a continuous system model is not easily realized in a computer, it is necessary to discretize the system model and discretize the state equation (2) and the measurement equation (9) to obtain a system model
Wherein, XkIs the state vector at time k, phik|k-1For the system one-step transfer matrix, Γ, from time k-1 to time kk-1Is a noise matrix of the system, which characterizes that each system noise from k-1 to k time respectively influences the brightness of each state at k time, Wk-1System noise at time k-1, ZkIs the measurement vector at time k, HkIs a measurement matrix at time k, VkMeasurement noise at time k
In the formula
Where T is the iteration period, TkIs the k moment;
(1.2) design of a federal filter:
each sub-filter adopts a Kalman filtering mode, and the method specifically comprises the following steps:
one-step prediction equation of state:
in the formula (I), the compound is shown in the specification,
is to utilize
Calculating to obtain X
kThe one-step prediction is carried out;
the state estimation equation:
is predicted in one step
Based on the measured value, the true value X is measured
kIs estimated, where K
kIs the filter gain; kalman gain equation:
in the formula, Pk|k-1Predicting the mean square error for one step; rkA variance matrix for the measured noise;
one-step prediction mean square error equation:
mean square error estimation equation:
in the formula, P
k|kTo estimate the value
The estimated mean square error equation of (2).
The position information representing the inertial navigation system is
In the formula ofI、LI、HIAs a measure of latitude, longitude, altitude, λ, of the inertial navigation systemt、Lt、HtThe latitude, longitude and altitude of the vehicle-mounted device are true values, and the delta lambda, delta L and delta H are measurement error values of the latitude, longitude and altitude of the inertial navigation system;
the velocity information representing the inertial navigation system is
In the formula vIN、vIE、vIUIs a measure of the velocity of the inertial navigation system in the northeast direction, vN、vE、vUIs the true value of the speed of the vehicle-mounted device in the northeast direction, delta vN、δvE、δvUMeasuring error value of the velocity of the inertial navigation system in the northeast direction;
the position information of the satellite navigation system is
In the formula ofG、LG、HGAs a measure of the satellite navigation system latitude, longitude, altitude, lambdat、Lt、HtIs the true value of latitude, longitude and altitude of the vehicle-mounted device, NE、NN、NUMeasuring error values of the satellite navigation system in the northeast direction;
the velocity information representing the satellite navigation system is
In the formula vGE、vGN、vGUAs a measure of the velocity of the satellite navigation system in the northeast direction, vN、vE、vUIs the true value of the speed of the vehicle-mounted device in the northeast direction, MN、ME、MUMeasuring error value of the velocity of the inertial navigation system in the northeast direction; the position measurement value N and the speed measurement value M are converted in order to be matched with the longitude and latitude dimensions of the inertial navigation system;
the speed information indicating the odometer is
In the formula vOE、vON、vOUAs a measure of the velocity of the odometer in the northeast direction, vN、vE、vUIs the true value of the speed of the vehicle-mounted device in the northeast direction, ON、OE、OUThe measurement error value of the speed of the odometer in the northeast direction is shown;
the altitude information indicating the altimeter is
Ha=HU-A (1.23)
In the formula HaIs a measure of the height of the altimeter,HUthe altitude measurement error value A is a true value of the position of the vehicle-mounted device in the vertical direction, and A is a measurement error value of the altimeter in the altitude;
(1.2.1) design of SINS/BDS sub-filter
From (2.1), the equation of state of the SINS/BDS sub-filter is known as
Measuring method of SINS/BDS sub-filter
Wherein
VG(t)=[NN NE NU ME MN MU]T (1.27)
The measured noise is treated as white noise, and its variance is respectively
R
M、R
NThe long radius and the short radius of the earth, respectively;
(1.2.2) design of SINS/odometer sub-filter
According to (1.1), the state equation of the SINS/BDS sub-filter is
The measurement equation of the SINS/odometer sub-filter is as follows
Wherein
HO(t)=[03×3 diag[1 1 1]03×12] (1.30)
VG(t)=[OE ON OU]T (1.31)
Measuring the white noise with the average value of 0;
(1.2.3) design of Federal Filter Main Filter
The federal filter is a two-stage filter structure, and the output X of a common reference subsystem (SINS)kThe main filter on the one hand and the individual sub-filters on the other hand are provided as measured values. The output of each subsystem is only fed to the respective filter. Local estimated value X of each sub-filteriAnd its covariance matrix PiThe estimated values sent into the main filter and the main filter are fused together to obtain a global estimated value;
global optimum estimation synthesized by main filter and sub-filter
And its corresponding covariance matrix P
gIs amplified into
And then feeding back to the sub-filter to reset the estimation value of the sub-filter, namely:
the main filter has a covariance matrix of
β
iDetermined according to the information distribution principle.
The invention comprehensively considers the filtering precision and the structural performance of the system, and designs a self-adaptive information fusion method based on vector distribution from the covariance matrix of the system and the observability of the system, and the method is described in detail in claim 4.
Step 2: after the output results of the sub-filters in the step 1 are obtained, fault detection is carried out in a vector distribution mode
And isolation, the specific method is as follows:
(2.1) sub-filter time update:
where i denotes the ith sub-filter.
And (2.2) fault diagnosis. The following fault diagnosis functions are first constructed:
wherein r isi,kRepresenting the residual of system i at time k, Λi,kIs a matrix of m rows and m columns, which can be expressed as:
when no fault occurs in the sub-filter, Λi,kEach element on the diagonal in the array should obey x with degree of freedom of 12And when a sensor in the system fails, the distribution is not satisfied. At this time, a proper threshold value is set, and the following judgment rule is established:
defining the measured noise coefficient B of the ith sub-filteri,kComprises the following steps:
wherein
By obtaining a measured noise figure B
i,kReconstructing the measured noise matrix
In equation (37), when a dimension of the measurement information is determined to be normal, B
i,kThe corresponding diagonal element is set to 1, otherwise to 0, thus reconstructing the metric noise matrix in equation (39)
For normal measurement variables, the corresponding noise variance after adjustment is unchanged; for the fault measurement variable, the corresponding noise variance after adjustment tends to be infinite, and dynamic isolation of the dimension information of the sensor fault is realized.
(2.3) sub-filter measurement update
And after the sub-filters perform measurement updating, transmitting the filtering result of the fault dimension information of the isolation sensor to the main filter for the next step of information fusion.
And step 3: and (3) constructing a vector distribution coefficient for each dimension of information of each sub-filter by using the information obtained in the step (2) fault detection, and carrying out information fusion in the main filter to obtain a global optimal estimation result. The method comprises the following specific steps:
covariance matrix P of sub-filtersi,k|kThe estimation precision of the sub-filters can be reflected, and the structural performance of the system can be reflected by the observability of the system. Conventional adaptive information distribution method makesUsing trace (P)i,k|k) The information distribution coefficients are calculated, but in the actual federal filter model, each sub-filter generally contains more than one measured variable, and each measured variable has different estimation accuracy even in the same filter. The invention designs a self-adaptive information distribution coefficient algorithm based on vector distribution based on the covariance matrix of the sub-filters and the observability of the system.
First, a sub-filter covariance matrix Pi,k|kAnd (3) carrying out characteristic value decomposition:
Pi,k|k=Di,kΛi,k(Di,k)T (1.41)
in the formula
Wherein λn,i,kIs the ith sub-filter covariance matrix Pi,k|kN characteristic value of (D)i,kIs an orthogonal matrix resulting from eigenvalue decomposition. Defining a distribution coefficient matrix Ai,kComprises the following steps:
Ai,ksatisfy the theorem of information conservation
The partition coefficient matrix C is constructed by the observability of the sub-filtersi,kLet us assume that the observability matrix of the sub-filter i is Qi,kTo Q, pairi,kPerforming singular value decomposition
Qi,k=Ui,kSi,k(Vi,k)T (1.46)
Wherein U isi,kAnd Vi,kIs an orthogonal matrix, Si,kThe method specifically comprises the following steps:
wherein Λr×r=diag{σ1,i,k,σ2,i,k…σri,i,k},σn,i,k(n=1,2,…ri),riAre respectively Qi,kSingular value and rank.
Then measure the coefficient Ci,kIs defined as:
Ci,ksatisfy the theorem of information conservation
Then the vector-based information assigns coefficient Bi,kComprises the following steps:
at the moment, the information distribution coefficient still meets the information conservation principle:
the asymmetry of the error covariance matrix of the system can destroy the consistent convergence stability of the Kalman filter, increase the filtering error and even lose the filtering effect. In order to ensure the symmetry of the error covariance matrix, the information distribution mode is as follows:
in summary, on the basis of a conventional GNSS/SINS integrated navigation algorithm, the invention designs a multi-source navigation system based on the Federal Kalman filtering algorithm, taking the SINS as a reference system and fusing the SINS/GNSS and the SINS/mileometer, thereby improving the navigation positioning precision of the integrated navigation system; aiming at the difference of estimation precision among sensors and among observation components of the same sensor, an algorithm for fault diagnosis and information distribution in a vector distribution mode is designed to form a self-adaptive federal fault-tolerant filter, so that the utilization rate of a system to navigation information is improved, and the precision and the reliability of a multi-source navigation system are enhanced.