Full strapdown laser seeker target tracking method integrating inter-frame pose information

Abstract

The present invention discloses a full-strapdown laser seeker target tracking method that integrates inter-frame pose information. Specifically, under conditions such as nonlinear target maneuvering out of the field of view, occlusion, loss of short-term laser irradiation signals, and blind spots, the inter-frame pose information is integrated to estimate the full-strapdown laser seeker angle information, thereby achieving full-strapdown laser seeker target tracking. The present invention can track targets under conditions such as nonlinear target maneuvering out of the field of view, occlusion, loss of short-term laser irradiation signals, and blind spots, and accurately provides target angle information. The method has the characteristics of low computational complexity and strong anti-interference capability, effectively reducing the support requirements for laser irradiation of the full-strapdown laser seeker, improving target tracking robustness, and providing support for achieving precise target strikes.

Description

Technical Field

[0001] The present invention relates to a technology for fusing posture information with full-strapdown laser tracking information, and in particular to a method for tracking a target with a full-strapdown laser seeker that fuses inter-frame posture information. The method is a real-time tracking method for a stationary target based on posture information, and can effectively reduce the guarantee requirements for irradiation by a laser illuminator of the full-strapdown laser seeker. The method can also handle phenomena such as nonlinear maneuvering out of the field of view, occlusion, and blind spots of the target during the tracking process. The method is suitable for guided weapons equipped with a full-strapdown laser seeker and an inertial measurement device and a positioning device. Background Art

[0002] A fully strapdown laser seeker has a large instantaneous optical field of view. However, its photodetector is fixed to a reference mount and is subject to significant disturbances from the carrier. During tracking, the target is prone to nonlinear maneuvers, such as out-of-field maneuvers, occlusions, short-term laser signal loss, and blind spots. Due to the irregular motion of the fully strapdown laser seeker in engineering applications, traditional processing methods such as least squares estimation, Kalman filtering, and extended Kalman filtering struggle to accurately estimate the target's laser signal. Under these conditions, the fully strapdown laser seeker is completely unable to accurately output operating status information, particularly angle information. Therefore, researching data that accurately reflects the fully strapdown laser seeker's operating process under these circumstances is of great significance and is a core technology for the stable tracking of fully strapdown laser seekers. Summary of the Invention

[0003] The present invention aims at tracking targets under conditions such as nonlinear maneuvering out of the field of view, occlusion, short-term laser illumination signal disappearance and blind spots. The present invention uses laser signals to solve angle information and fuses inter-frame posture information to provide a full strapdown laser seeker target tracking method based on inter-frame posture information.

[0004] The technical solution adopted in the present invention is as follows:

[0005] A full strapdown laser seeker target tracking method that integrates inter-frame pose information, namely, when the target nonlinearly maneuvers out of the field of view, is blocked, the short-term laser illumination signal disappears, and there is a blind spot, the inter-frame pose information is integrated to estimate the full strapdown laser seeker angle information, thereby achieving full strapdown laser seeker target tracking. The steps of implementing the method are as follows:

[0006] (1) establishing an angle estimation model that fuses inter-frame pose information, wherein the angle estimation model includes a position transformation model and a posture transformation model;

[0007] (2) Full strapdown laser seeker target tracking using laser detector signals to calculate angle information and fuse posture information.

[0008] Furthermore, the establishment of the angle estimation model for fusing inter-frame pose information in step (1) involves the following coordinate systems:

[0009] Geocentric coordinate system O e -X e Y e Z e , with the Earth's center of mass O e The spatial rectangular coordinate system established as the origin; O e X e The axis points to the starting meridian at a certain time t0 in the equatorial plane, O e Z e The axis is perpendicular to the equatorial plane and points to the North Pole; e Y e The axes are determined by the right-hand rule.

[0010] Geographic Coordinate System n -X n Y n Z n , according to the navigation coordinate system defined by the North Celestial East, the origin of the coordinate system is the center of mass of the missile body O n , O n Y n At the point where the geographic coordinate system reference ellipsoid intersects, O is collinear with the normal of the ellipsoid. n Y n With O n X n The axis is vertical, lies on the meridian plane and points north, O n Z n The axes are determined by the right-hand rule.

[0011] Projectile coordinate system O b -X b Y b Z b , with the center of mass O of the projectile b The spatial rectangular coordinate system established as the origin; O b X b The axis is the center axis of the projectile, and the direction points to the head of the projectile. b Y b The axis is located in the main symmetry plane of the projectile, perpendicular to O b X b , upward is positive, O b Z b The axis is perpendicular to the main symmetry plane and is determined by the right-hand rule.

[0012] Detector coordinate system The origin is located at the intersection of the four quadrant voltages and the difference is 0, O d -θ axis and Axes are parallel to the detector plane, O d -θ is the elevation angle, with upward being positive; is the azimuth, positive to the right.

[0013] If the spatial target point E t The position coordinates of t ,L t ,h t ), the position E0 of the projectile at time t0 is (λ0, L0, h0), and the quaternion posture is q0 = [q 00 ,q 10 ,q 20 ,q 30 ], the position E1 of the projectile at time t1 is (λ1, L1, h1), and the quaternion posture is q1 = [q 01 ,q 11 ,q 21 ,q 31 ].

[0014] Between adjacent frames or in a short time, assuming that the geographical system is the same, the angle estimation model that integrates the pose information includes a position transformation model and a posture transformation model.

[0015] The position transformation model first calculates the coordinates of the position at time t0 and the target position in the geocentric system:

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022] Where a e ,b e is the radius of the Earth's ellipsoid; R wt R is the curvature radius of the circle at time t0; N R is the radius of curvature of the meridian at time t0; wt1 R is the curvature radius of the target position circle; N1 is the meridian curvature radius of the target position; (λ t ,L t ,h t ) is the latitude and longitude data of the target location;

[0023] Subtracting the two results in the relative position vector △E0:

[0024] △E0=E0-E t(7)

[0025] Then the Euclidean distance can be expressed as:

[0026] Dis(E0,E t )=norm(△E0,2) (8)

[0027] Similarly, the relative position vector △E1 at time t1 can be obtained:

[0028] △E1=E1-E t (9)

[0029] Then the Euclidean distance can be expressed as:

[0030] Dis(E1,E t )=norm(△E1,2) (10)

[0031] Then, the position transformation relative vector △E1-△E0 is transformed according to the geocentric system → geographic system → missile system → detector coordinate system. According to the pinhole model and the coordinate transformation relationship between the geocentric system and the detector coordinate system, the angle change model caused by the target position change from time t0 to time t1 can be obtained:

[0032]

[0033]

[0034]

[0035] in is the cosine matrix from the geocentric system to the geographic system at time t1, It is the cosine matrix from the geographic system to the missile system at time t1.

[0036] Posture transformation model, from the detector coordinate system angle information at time t0 According to the coordinate transformation of detector coordinate system → missile coordinate system → geographic system, the coordinates of the target at time t1 in the geographic system are:

[0037]

[0038]

[0039] in is the transformation matrix from the elastic system to the geographic system at time t0, is the conversion matrix from geographic system to missile system at time t1, which can be calculated by formula (13);

[0040] Target angle to be determined at time t1 Then, the coordinates of the elastic system are proportional according to time t1:

[0041]

[0042] According to formula (16), we can get:

[0043]

[0044] Combining the position transformation model and the posture transformation model, the angle estimation model that finally obtains the fusion posture information is:

[0045]

[0046] Furthermore, the use of laser detector signals to calculate angle information in step (2) refers to the use of the angle estimation model in step 1 to estimate the target angle when the target nonlinearly maneuvers out of the field of view, is blocked, or the laser irradiation signal disappears during the tracking process, and the full-strap laser seeker cannot receive the laser signal.

[0047] Furthermore, the use of laser detector signals to calculate angle information in step (2) means that when approaching a blind spot during the tracking process, the laser signal energy becomes increasingly stronger and may reach the gain adjustment limit, resulting in inaccurate measurement of the target angle. In this case, the angle estimation model of step one is used to estimate the target angle.

[0048] Furthermore, in step (2), the angle information is calculated using the laser detector signal. During the normal tracking process, the angle estimation model of step 1 can also be used to estimate the target angle.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] The method of the present invention can track the target under conditions such as the target nonlinearly maneuvering out of the field of view, occlusion, short-term laser irradiation signal disappearance and blind spots, and accurately provide target angle information; and has the characteristics of low computational complexity and strong anti-interference ability, which can effectively reduce the guarantee requirements for the use of laser irradiators for full strapdown laser seekers, improve the robustness of target tracking, and provide support for achieving precise target strikes. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 Schematic diagram of the inter-frame pose information transformation model of the present invention;

[0052] Figure 2 Schematic diagram of the tracking method of the present invention. DETAILED DESCRIPTION

[0053] The technical solutions in the embodiments of the present invention are described clearly and completely below with reference to the accompanying drawings.

[0054] A full strapdown laser seeker target tracking method that integrates inter-frame pose information in this embodiment can estimate the full strapdown laser seeker angle information by integrating inter-frame pose information under conditions such as nonlinear target maneuvering out of the field of view, occlusion, short-term laser illumination signal disappearance, and blind spots, thereby achieving full strapdown laser seeker target tracking. The specific implementation steps are as follows:

[0055] Step 1: Establish an angle estimation model that fuses inter-frame pose information.

[0056] The coordinate systems involved in establishing the angle estimation model include:

[0057] Geocentric coordinate system O e -X e Y e Z e , with the Earth's center of mass O e The spatial rectangular coordinate system established as the origin; O e X e The axis points to the starting meridian at a certain time t0 in the equatorial plane, usually the meridian where the Greenwich Observatory is located. e Z e The axis is perpendicular to the equatorial plane and points to the North Pole; e Y e The axes are determined by the right-hand rule.

[0058] Geographic Coordinate System n -X n Y n Z n , usually refers to the North Celestial East coordinate system or navigation coordinate system. The navigation coordinate system defined by the North Celestial East has its origin at the center of mass of the missile body O n , O n Y n At the point where the geographic coordinate system reference ellipsoid intersects, O is collinear with the normal of the ellipsoid. n Y n With O n X n The axis is vertical, lies on the meridian plane and points north, O n Z n The axes are determined by the right-hand rule.

[0059] Projectile coordinate system O b -X b Y b Z b , with the center of mass O of the projectile b The spatial rectangular coordinate system established as the origin; O b X b The axis is the center axis of the projectile, and the direction points to the head of the projectile. b Y b The axis is located in the main symmetry plane of the projectile, perpendicular to O bX b , upward is positive, O b Z b The axis is perpendicular to the main symmetry plane and is determined by the right-hand rule.

[0060] Detector coordinate system The origin is located at the intersection of the four quadrant voltages and the difference is 0, O d -θ axis and Axes are parallel to the detector plane, O d -θ is the elevation angle, with upward being positive; is the azimuth, positive to the right.

[0061] like Figure 1 As shown, if the spatial target point E t The position coordinates of t ,L t ,h t ), the position E0 of the projectile at time t0 is (λ0, L0, h0), and the quaternion posture is q0 = [q 00 ,q 10 ,q 20 ,q 30 ], the position E1 of the projectile at time t1 is (λ1, L1, h1), and the quaternion posture is q1 = [q 01 ,q 11 ,q 21 ,q 31 ].

[0062] Between adjacent frames or in a short time, assuming that the geographical system is the same, the angle estimation model that integrates the pose information includes a position transformation model and a posture transformation model.

[0063] The position transformation model first calculates the coordinates of the position at time t0 and the target position in the geocentric system:

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070] Where a e ,b e is the radius of the Earth's ellipsoid; R wt R is the curvature radius of the circle at time t0; NR is the radius of curvature of the meridian at time t0; wt1 R is the curvature radius of the target position circle; N1 is the meridian curvature radius of the target position; (λ t ,L t ,h t ) is the latitude and longitude data of the target location;

[0071] Subtracting the two results in the relative position vector △E0:

[0072] △E0=E0-E t (7)

[0073] Then the Euclidean distance can be expressed as:

[0074] Dis(E0,E t )=norm(△E0,2) (8)

[0075] Similarly, the relative position vector △E1 at time t1 can be obtained:

[0076] △E1=E1-E t (9)

[0077] Then the Euclidean distance can be expressed as:

[0078] Dis(E1,E t )=norm(△E1,2) (10)

[0079] Then, the position transformation relative vector △E1-△E0 is transformed according to the geocentric system → geographic system → missile system → detector coordinate system. According to the pinhole model and the coordinate transformation relationship between the geocentric system and the detector coordinate system, the angle change model caused by the target position change from time t0 to time t1 can be obtained:

[0080]

[0081]

[0082]

[0083] in is the cosine matrix from the geocentric system to the geographic system at time t1, It is the cosine matrix from the geographic system to the missile system at time t1.

[0084] Posture transformation model, from the detector coordinate system angle information at time t0 Perform coordinate transformation according to the detector coordinate system → missile coordinate system → geographic system, and obtain the target coordinates in the geographic system at time t1:

[0085]

[0086]

[0087] in is the transformation matrix from the elastic system to the geographic system at time t0, is the conversion matrix from geographic system to missile system at time t1, which can be calculated by formula (13).

[0088] Target angle to be determined at time t1 Then, the coordinates of the elastic system are proportional according to time t1:

[0089]

[0090] According to formula (16), we can get:

[0091]

[0092] Combining the position transformation model and the posture transformation model, the angle estimation model that finally obtains the fusion posture information is:

[0093]

[0094] The errors that affect the angle estimation of formula (18) include: drift factor error, error caused by angular vibration of the projectile, inconsistency error in the fusion time of posture information and laser signal data, and angular velocity error.

[0095] Drift error: Since the estimation is based on inter-frame pose information, the inherent bias error of the pose information can be ignored, and the up and down frame time is very short, generally 50ms, so the drift error can be ignored.

[0096] Projectile angular vibration error: During the flight of the projectile, affected by aerodynamic forces, the maximum angular error caused by the projectile angular vibration is 0.1°;

[0097] The time inconsistency error between the fusion of posture information and laser signal data: The maximum time error of posture information in engineering is 5ms. Considering that the posture angular velocity is less than 15° / s, the maximum angle error caused is 0.075°.

[0098] Angular velocity error: The maximum angular velocity error measured by the system is 0.5° / s. The time interval is generally 50ms, resulting in a maximum angle error of 0.025°.

[0099] Comprehensive analysis of the above main errors shows that the total angle error is no more than 0.2°.

[0100] Step 2: latch the posture information, combine it with the laser signal to perform sum and difference operations to solve the target angle, and realize full strapdown laser seeker target tracking that integrates posture information.

[0101] During the tracking process, it is easy for the target to maneuver nonlinearly out of the field of view, be blocked, or the laser illumination signal to disappear. During this process, the full strapdown laser seeker cannot receive the laser signal, and step one can be used to estimate the target angle.

[0102] When approaching the blind spot during the tracking process, the laser signal energy becomes increasingly stronger and may reach the gain adjustment limit, resulting in inaccurate target angle measurement. In this case, step 1 can be used to estimate the target angle.

[0103] During the normal tracking process, step 1 can also be used to estimate the target angle.

[0104] Combining steps one and two, we get Figure 2 The flowchart shown can estimate the target's angle information in real time, and realize target tracking under conditions such as target nonlinear maneuvering out of the field of view, occlusion, short-term laser irradiation signal disappearance and blind spots; it can effectively reduce the guarantee requirements for the use of laser irradiator irradiation by the full strapdown laser seeker, and can improve the robustness of target tracking.

[0105] The above embodiments are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. These changes and improvements are all within the scope of protection claimed by the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A full strapdown laser seeker target tracking method integrating inter-frame pose information, characterized in that: Under the conditions of nonlinear target maneuvering out of the field of view, occlusion, short-term laser illumination signal disappearance and blind spots, the full strapdown laser seeker angle information is estimated by fusing inter-frame pose information, thereby achieving full strapdown laser seeker target tracking. The specific implementation steps are as follows: (1) establishing an angle estimation model that fuses inter-frame pose information, wherein the angle estimation model includes a position transformation model and a posture transformation model; (2) Full strapdown laser seeker target tracking using laser detector signals to calculate angle information and fuse pose information; The establishment of the angle estimation model for fusing inter-frame pose information in step (1) involves the following coordinate systems: Geocentric coordinate system O e -X e Y e Z e , with the Earth's center of mass O e The spatial rectangular coordinate system established as the origin; O e X e The axis points to the starting meridian at a certain time t0 in the equatorial plane, O e Z e The axis is perpendicular to the equatorial plane and points to the North Pole; e Y e The axis is determined by the right-hand rule; Geographic Coordinate System n -X n Y n Z n , according to the navigation coordinate system defined by the North Celestial East, the origin of the coordinate system is the center of mass of the missile body O n , O n Y n At the point where the geographic coordinate system reference ellipsoid intersects, O is collinear with the normal of the ellipsoid. n Y n With O n X n The axis is vertical, lies on the meridian plane and points north, O n Z n The axis is determined by the right-hand rule; Projectile coordinate system O b -X b Y b Z b , with the center of mass O of the projectile b The spatial rectangular coordinate system established as the origin; O b X b The axis is the center axis of the projectile, and the direction points to the head of the projectile. b Y b The axis is located in the main symmetry plane of the projectile, perpendicular to O b X b , upward is positive, O b Z b The axis is perpendicular to the main symmetry plane and is determined by the right-hand rule; Detector coordinate system The origin is located at the intersection of the four quadrant voltages and the difference is 0, O d -θ axis and Axes are parallel to the detector plane, O d -θ is the elevation angle, with upward being positive; is the azimuth, positive to the right; If the spatial target point E′ t The position coordinates of t ,L t ,h t ), the position of the projectile at time t0 is E′0 (λ0, L0, h0), and the quaternion posture is q0 = [q 00 ,q 10 ,q 20 ,q 30 ], the position of the projectile at time t1 is E′1 (λ1, L1, h1), and the quaternion posture is q1 = [q 01 ,q 11 ,q 21 ,q 31 ]; Between adjacent frames or within a short period of time, assuming that the geographical system is the same, the angle estimation model that integrates the pose information includes a position transformation model and a pose transformation model; The position transformation model first calculates the coordinates of the position at time t0 and the target position in the geocentric system: Where a e ,b e is the radius of the Earth's ellipsoid; R wt R is the curvature radius of the circle at time t0; N R is the radius of curvature of the meridian at time t0; wt1 R is the curvature radius of the target position circle; N1 is the meridian curvature radius of the target position; (λ t ,L t ,h t ) is the latitude and longitude data of the target location; Subtracting the two results in the relative position vector ΔE0: ΔE0=E0-E t (7) Then the Euclidean distance can be expressed as: This(E0,E t )=norm(ΔE0,2) (8) Similarly, the relative position vector ΔE1 at time t1 can be obtained: ΔE1=E1-E t (9) Then the Euclidean distance can be expressed as: Dis(E1,E t )=norm(ΔE1,2) (10) Then, the position transformation relative vector ΔE1-ΔE0 is transformed according to the geocentric system → geographic system → projectile system → detector coordinate system. Based on the pinhole model and the coordinate transformation relationship between the geocentric system and the detector coordinate system, the angle change model caused by the target position change from time t0 to time t1 can be obtained: in is the cosine matrix from the geocentric system to the geographic system at time t1, is the cosine matrix from the geographic system to the missile system at time t1; Posture transformation model, from the detector coordinate system angle information at time t0 According to the coordinate transformation of detector coordinate system → missile coordinate system → geographic system, the coordinates of the target at time t1 in the geographic system are: in is the transformation matrix from the elastic system to the geographic system at time t0, is the conversion matrix from geographic system to missile system at time t1, which can be calculated by formula (13); Target angle to be determined at time t1 Then, the coordinates of the elastic system are proportional according to time t1: According to formula (16), we can get: Combining the position transformation model and the posture transformation model, the angle estimation model that finally obtains the fusion posture information is:

2. The full strapdown laser seeker target tracking method according to claim 1, wherein: The method of calculating the angle information by using the laser detector signal in step (2) means that when the target nonlinearly maneuvers out of the field of view, is blocked, or the laser irradiation signal disappears during the tracking process, and the full-strap laser seeker cannot receive the laser signal, the angle estimation model in step (1) is used to estimate the target angle.

3. The full strapdown laser seeker target tracking method according to claim 2, wherein: The method of calculating the angle information using the laser detector signal in step (2) means that when approaching a blind spot during the tracking process, the laser signal energy becomes increasingly stronger and reaches the gain adjustment limit, resulting in inaccurate target angle measurement. The angle estimation model in step (1) is used to estimate the target angle.

4. The full strapdown laser seeker target tracking method according to claim 3, wherein: In step (2), the angle information is calculated using the laser detector signal. During the normal tracking process, the angle estimation model of step (1) is used to estimate the target angle.

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