A method for over-the-top tracking of a roll-pitch type airborne photoelectric detection device

Abstract

The present application relates to the technical field of photoelectric detection and tracking, and particularly relates to a kind of horizontal roll-pitch type airborne photoelectric detection equipment over-the-top tracking method, comprising the following steps: in tracking mode, first determine whether the sight line enters over-the-top area, if true, it indicates that it enters over-the-top area, otherwise, the method is not executed;Second, calculate the initial sight line and sight line angular velocity when entering over-the-top area;Third, calculate the sight line rotation matrix with time parameter;Third, calculate the sight line and horizontal roll frame angle of over-the-top point;Finally, the horizontal roll frame moves to the estimated over-the-top position and waits for the sight line to exit over-the-top area.After entering over-the-top area, the stable platform normally tracks, but the horizontal roll frame is no longer driven by the azimuth frame.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectric detection and tracking, and in particular to an overhead tracking method for a roll-pitch type airborne photoelectric detection device. Background Art

[0002] The roll-pitch airborne photoelectric detection equipment is an airborne ground-to-ground photoelectric detection system, which generally has a photoelectric imaging component that can be used to search, identify and track targets.

[0003] Roll-pitch airborne photoelectric detection equipment utilizes a three-axis gimbaled roll-pitch-azimuth frame for boresight pointing. The pitch-azimuth frame forms a two-axis stabilized platform, stabilized by an inertial measurement unit mounted within the platform. The roll frame acts as an external frame, tracking the azimuth frame's movements to ensure it avoids mechanical limits.

[0004] However, when the pitch angle is close to 0 degrees, the line of sight is directly in front of the airborne optoelectronic detection equipment, that is, in the overhead area, the roll axis and the azimuth axis are close to vertical, and the roll frame lacks the freedom to follow the azimuth frame, which will cause the pod to be out of control. Summary of the Invention

[0005] The present invention addresses the challenges of existing overhead tracking technology by proposing an overhead tracking method for a roll-pitch airborne photoelectric detection device based on the angular velocity of the line of sight. The key concept of the present invention is to linearly extrapolate the angular velocity of the line of sight tracking to predict the movement of the line of sight within the overhead region. This is then inversely calculated to translate the line of sight angle into the angle, enabling the roll frame to be moved out of the overhead region in advance.

[0006] The object of the present invention is to provide a roll-pitch type airborne photoelectric detection device overhead tracking method, comprising:

[0007] Step 1: In the tracking mode, determine whether the sighting line of the airborne photoelectric detection device enters the overhead area. If it enters the overhead area, execute step 2; otherwise, continue to execute step 1;

[0008] Step 2: Calculate the initial aiming line and aiming line angular velocity when entering the overhead area based on the frame angle and frame angular velocity at the time of entering the overhead area;

[0009] Step 3: Calculate the line of sight rotation matrix with time parameters according to the line of sight angular velocity;

[0010] Step 4: Estimate the line of sight and roll frame angle in the over-the-top area based on the angular motion equation at the over-the-top moment.

[0011] Step 5: The roll frame moves to the estimated exit position and waits for the aiming line to exit the overhead area.

[0012] Step 6: After the line of sight enters the overhead area, the stabilized platform tracks normally, but the roll frame is no longer slaved to the azimuth frame;

[0013] Step 7: After the sight line of the airborne photoelectric detection equipment leaves the over-the-top area, the roll frame is driven by the azimuth frame and returns to step 1 to determine the next over-the-top.

[0014] Preferably, in step one, the method for determining whether the aiming line of the airborne photoelectric detection device enters the over-the-top area is to compare the projection of the aiming line of the base system of the airborne photoelectric detection device in the roll direction with the size of the threshold η. When it is greater than the threshold η, the aiming line enters the over-the-top area, otherwise it is not in the over-the-top area.

[0015] Preferably, the threshold η is related to the range of the overhead angle, specifically:

[0016] η=cosμ

[0017] Where μ is the single-side vertex angle.

[0018] Preferably, in step 2, the calculation formula for the initial aiming line when entering the overhead area is:

[0019]

[0020] Where, los b0 Initial sighting line when tying the base over the overhead area;

[0021] The rotation matrix from the stable platform system to the base system is calculated based on the initial frame angle entering the overhead area; los a0 Tie the line of sight to stabilize the platform.

[0022] Preferably, in step 2, the calculation formula for the angular velocity of the line of sight is:

[0023]

[0024] In the formula, ψ, are the azimuth frame angle and angular velocity, respectively;

[0025] θ、 are the pitch frame angle and angular velocity, respectively;

[0026] is the roll frame angular velocity.

[0027] Preferably, in step 3, the calculation formula of the line of sight rotation matrix with time parameters is:

[0028] C(t)=cos(|ω b |t)I+(1-cos(|ω b |t))nnT +sin(|ω b |t)n^

[0029] Where t is the time parameter;

[0030] ω b is the angular velocity vector ω of the line of sight b The amplitude of

[0031] I is the identity matrix;

[0032] n is the angular velocity vector ω of the line of sight b direction;

[0033] n^ is the anti-multiplication matrix formed by n;

[0034] n T is the transpose of n.

[0035] Preferably, in step 4, the angular motion relationship equation at the time of passing the top is specifically:

[0036]

[0037] Where, los bt The aiming line of the base system is set for the moment of passing the top;

[0038] los bt (1) for los bt The component in the x-direction is the projection of the base system's sight line in the roll direction at the moment of passing the top;

[0039] Solving the above equation yields the non-zero time parameter t, which can be used to estimate the base system's line of sight los in the overhead region. bt .

[0040] Preferably, in step 4, the step of estimating the roll frame angle of the overhead area is:

[0041] First, calculate the roll frame angle of the first vertex based on the frame coupling relationship:

[0042] φ bt 1=-atan(los bt (2),los bt (3)

[0043] Where, los bt (2),los bt (3) The base system sight line los at the time of passing the top bt Components in the y and z directions;

[0044] Next, calculate and φ bt1 The second roll frame angle that passes the vertex is 180° different;

[0045]

[0046] Finally, φ bt 1.φ bt 2. Compared with the initial roll frame angle when entering the over-the-top area, the value with the smallest angle difference is used as the estimated roll frame angle of the over-the-top area.

[0047] Preferably, before entering the over-the-top area, the stable platform composed of the pitch frame and the azimuth frame moves in a closed-loop according to the tracking deviation, and the roll frame is driven by the azimuth frame to maintain the azimuth frame angle close to zero degrees; after entering the over-the-top area, the roll frame moves toward the roll frame angle estimated for the over-the-top area, and the stable platform composed of the pitch frame and the azimuth frame moves in a closed-loop according to the tracking deviation; after exiting the over-the-top area, the control strategy before entering the over-the-top is restored.

[0048] The present invention has at least the following beneficial effects:

[0049] The present invention provides a roll-pitch airborne photoelectric detection device overhead tracking method. The present invention can plan the frame movement in the overhead area in advance, so that the control system is always in a normal working state, the tracking error is controllable, and the continuity and smoothness of tracking are guaranteed when entering and exiting the overhead area. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a schematic diagram of the principle of the overhead tracking method of the roll-pitch airborne photoelectric detection equipment provided by the present invention.

[0051] Figure 2 Flowchart of the overhead tracking method for roll-pitch airborne photoelectric detection equipment provided by the present invention. DETAILED DESCRIPTION

[0052] In order to illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the following is a detailed description with reference to the embodiments.

[0053] The base system in the present invention is defined as O as the rotation center of the three-axis universal ring frame in roll, pitch and azimuth, OX b Axis pointing to the roll axis, OY b Vertical roll axis right, OZ b Perpendicular to the longitudinal axis of the roll-pitch airborne photoelectric detection equipment, it forms the "front right lower" base coordinate system OX b Y b Z b .

[0054] The stable platform of the present invention is defined as: the base OX b Yb Z b The coordinate system is obtained by rotating the frame angles around the roll axis, pitch axis and azimuth axis of the optoelectronic pod in sequence, and its positive x-axis direction is the visual axis of the optoelectronic pod.

[0055] The direction of the azimuth and elevation angles of the sighting line is determined by the base system OX b Y b Z b The direction is determined by the right hand.

[0056] The method provided by the present invention comprises the following steps:

[0057] Step 1: Before entering the overhead area, the stable platform composed of the pitch frame and azimuth frame moves in a closed loop based on the tracking deviation, with the roll frame driven by the azimuth frame to maintain the azimuth frame angle close to zero degrees. In tracking mode, determine whether the airborne photoelectric detection device's line of sight enters the overhead area. If so, execute steps 2 and 6; otherwise, return to step 1.

[0058] The method for judging whether the aiming line of the airborne photoelectric detection device has entered the over-the-top area is to compare the projection of the aiming line of the base system of the airborne photoelectric detection device in the roll direction with the size of the threshold η. When it is greater than the threshold η, the aiming line enters the over-the-top area, otherwise it is not in the over-the-top area.

[0059] The threshold η is related to the range of the overhead angle, specifically:

[0060] η=cosμ

[0061] Where μ is the unilateral overshoot angle, which should not be greater than the maximum misalignment angle of the stable platform and should leave a certain margin.

[0062] Step 2: Calculate the initial aiming line and aiming line angular velocity when entering the overhead area based on the frame angle and frame angular velocity at the time of entering the overhead area;

[0063] The formula for calculating the initial aiming line when entering the overhead zone is:

[0064]

[0065] Where, los b0 Initial sighting line when tying the base over the overhead area;

[0066] The rotation matrix from the stable platform system to the base system is calculated based on the initial frame angle entering the overhead region;

[0067] los a0 Tie the line of sight to stabilize the platform.

[0068] The calculation formula of the angular velocity of the line of sight is:

[0069]

[0070] In the formula, ψ, is the azimuth frame angle and angular velocity;

[0071] θ、 is the pitch frame angle and angular velocity;

[0072] is the roll frame angular velocity.

[0073] Step 3: Calculate the line of sight rotation matrix with time parameters according to the line of sight angular velocity;

[0074] The calculation formula of the line of sight rotation matrix with time parameters is:

[0075] C(t)=cos(|ω b |t)I+(1-cos(|ω b |t))nn T +sin(|ω b |t)n^

[0076] Where t is the time parameter;

[0077] |ω b | is the angular velocity vector ω of the line of sight b The amplitude of

[0078] I is the identity matrix;

[0079] n is the angular velocity vector ω of the line of sight b direction;

[0080] n^ is the anti-multiplication matrix formed by n;

[0081] n T is the transpose of n.

[0082] Step 4: Estimate the line of sight and roll frame angle in the over-the-top area based on the angular motion equation at the over-the-top moment.

[0083] The specific equation of angular motion at the time of passing the top is:

[0084]

[0085] Where, los bt The aiming line of the base system is set for the moment of passing the top;

[0086] los bt (1) for los bt The component in the x-direction is the projection of the base system's sight line in the roll direction at the moment of passing the top;

[0087] Solving the above equation yields the non-zero time parameter t, which can be used to estimate the base system's line of sight los in the overhead region. bt .

[0088] The steps to estimate the roll frame angle in the overhead area are:

[0089] First, calculate the roll frame angle of the first vertex based on the frame coupling relationship:

[0090] φ bt 1=-atan(los bt (2),los bt (3)

[0091] Where, los bt (2),los bt (3) The base system sight line los at the time of passing the top bt Components in the y and z directions;

[0092] Next, calculate and φ bt 1 The second roll frame angle that passes the vertex is 180° different;

[0093]

[0094] Finally, φ bt 1.φ bt 2. Compared with the initial roll frame angle when entering the over-the-top area, the value with the smallest angle difference is used as the estimated roll frame angle of the over-the-top area.

[0095] Step 5: The roll frame moves to the estimated exit position and waits for the aiming line to exit the overhead area.

[0096] Step 6: After the line of sight enters the overhead area, the stabilized platform tracks normally, but the roll frame is no longer slaved to the azimuth frame. The stabilized platform composed of the pitch frame and azimuth frame performs closed-loop control based on the tracking image deviation.

[0097] Step 7: After the airborne photoelectric detection equipment's aiming line leaves the over-the-top area, the control strategy before entering the over-the-top area is restored. The roll frame is driven by the azimuth frame, and the process returns to step 1 to determine the next over-the-top situation.

[0098] In order to illustrate the overhead tracking method of a roll-pitch airborne photoelectric detection device provided by the present invention, it is further described with reference to the accompanying drawings.

[0099] See also Figure 1As shown, 101 is the roll-pitch airborne photoelectric detection device and its carrier, and 102 is the angle of the cone corresponding to the overhead region, i.e., the overhead angle. The unilateral overhead angle should not exceed the maximum misalignment angle of the stabilized platform, with a certain margin. In a preferred embodiment of the present invention, the maximum misalignment angle range of the stabilized platform is ±5°, with a unilateral overhead angle of 4.5° and an overhead angle of 9°. In other words, the overhead region of the preferred embodiment of the present invention is defined as the area within a 9° cone directly in front of the base system's line of sight.

[0100] Before entering the overhead zone, the stable platform composed of the pitch frame and the azimuth frame moves in a closed loop according to the tracking deviation, and the roll frame is driven by the azimuth frame to maintain the azimuth frame angle close to zero. At a certain moment, the projection of the line of sight 103 on the roll axis is just greater than the threshold value η, indicating that it has entered the overhead zone. The threshold value is the cosine of the unilateral overhead angle. When the projection of the line of sight on the roll axis is greater than the threshold value η, for a preferred embodiment of the present invention, the unilateral overhead angle is 4.5°, then the threshold value η is

[0101] η=cosμ=0.9969

[0102] The aiming line 103 is the initial aiming line for entering the overhead area. The initial aiming line and the aiming line angular velocity 104 for entering the overhead area are calculated based on the frame angle and frame angular velocity at the time of entering the overhead area:

[0103]

[0104] In the formula, ψ, is the azimuth frame angle and angular velocity;

[0105] θ、 is the pitch frame angle and angular velocity;

[0106] is the roll frame angular velocity.

[0107] Given the angular velocity, multiply it by time to get the rotation vector, and then substitute it into the Rodriguez formula to get the line of sight rotation matrix related to the time parameter:

[0108] C(t)=cos(|ω b |t)I+(1-cos(|ω b |t))nn T +sin(|ω b |t)n^

[0109] Where t is the time parameter;

[0110] |ω b | is the angular velocity vector ω of the line of sight b The amplitude of

[0111] I is the identity matrix;

[0112] n is the angular velocity vector ω of the line of sight b direction;

[0113] n^ is the anti-multiplication matrix formed by n;

[0114] n T is the transpose of n.

[0115] After time t, the aiming line moves to position 105 in the overhead area. According to the initial aiming line and the aiming line rotation matrix, the aiming line at position 105 satisfies the following equation:

[0116] los bt =C(t)los b0

[0117] At position 105, the aiming line is still in the overhead area, so the following relationship is satisfied:

[0118] los bt (1) = η

[0119] Where, los bt The base is aimed at the moment of passing the top.

[0120] By combining the above two equations, we can estimate the line of sight angle in the overhead area. And then we can calculate the corresponding roll frame angle from the estimated line of sight angle in the overhead area. For roll-pitch airborne photoelectric detection equipment, since the pitch frame can move in both positive and negative directions, there are two roll frame angles corresponding to the overhead area. The difference between the two roll frame angles is 180 degrees, and the corresponding pitch frame angles have opposite signs. Therefore, we first calculate the first roll frame angle:

[0121] φ bt 1=-atan(los bt (2),los bt (3)

[0122] Next, calculate and φ bt 1 The second roll frame angle that passes the vertex is 180° different;

[0123]

[0124] Finally, φ bt 1.φ bt2. The roll angle at the initial entry into the flyover region is compared to the angle with the smallest difference, and the angle with the smallest difference is used as the estimated roll angle for the flyover region. This approach minimizes the roll angle, ensuring the fastest roll rotation to the desired position during high-speed flyovers. After entering the flyover region, the roll angle moves in accordance with the estimated roll angle for the flyover region, while the stable platform composed of the pitch and azimuth angles maintains closed-loop motion based on the tracking error. After exiting the flyover region, the control strategy prior to entering the flyover region is restored.

[0125] In order to further illustrate the specific embodiments of the present invention, Figure 2 The process of the present invention is described in detail.

[0126] Step 200: When the airborne photoelectric detection device is in tracking mode and has not yet entered the overhead area, the stable platform composed of the pitch frame and the azimuth frame moves in a closed loop according to the tracking deviation, and the roll frame is driven by the azimuth frame to maintain the azimuth frame angle close to zero degrees.

[0127] Step 201, determining whether the sighting line of the airborne photoelectric detection device enters the overhead area, if so, executing steps 202 and step 6, otherwise returning to step 208;

[0128] The method for judging whether the aiming line of the airborne photoelectric detection device has entered the over-the-top area is to compare the projection of the aiming line of the base system of the airborne photoelectric detection device in the roll direction with the size of the threshold η. When it is greater than the threshold η, the aiming line enters the over-the-top area, otherwise it is not in the over-the-top area.

[0129] The threshold η is related to the range of the overhead angle, specifically:

[0130] η=cosμ

[0131] Where μ is the unilateral pass angle, which should not be greater than the maximum misalignment angle of the stabilization platform, with a certain margin. In a preferred embodiment of the present invention, the maximum misalignment angle range of the stabilization platform is ±5°, with a unilateral pass angle of 4.5° and a pass angle of 9°. Specifically, the pass area of ​​the preferred embodiment of the present invention is within a 9° cone directly in front of the base system's line of sight.

[0132] Step 202, calculating the initial aiming line entering the overhead area according to the frame angle at the moment of entering the overhead area;

[0133] The formula for calculating the initial aiming line when entering the overhead zone is:

[0134]

[0135] Where, los b0 Initial sighting line when tying the base over the overhead area;

[0136] The rotation matrix from the stable platform system to the base system is calculated based on the initial frame angle entering the overhead region;

[0137] los a0 Tie the line of sight to stabilize the platform.

[0138] Step 203: Calculate the angular velocity of the line of sight entering the overhead area based on the frame angle and frame angular velocity at the time of entering the overhead area. The calculation formula of the line of sight angular velocity is:

[0139]

[0140] In the formula, ψ, is the azimuth frame angle and angular velocity;

[0141] θ、 is the pitch frame angle and angular velocity;

[0142] is the roll frame angular velocity.

[0143] Step 204: Calculate the line of sight rotation matrix with time parameters based on the line of sight angular velocity. The specific algorithm is to multiply the known angular velocity by time to obtain the rotation vector, and then substitute it into the Rodriguez formula to obtain the line of sight rotation matrix with the time parameters:

[0144] C(t)=cos(|ω b |t)I+(1-cos(|ω b |t))nn T +sin(|ω b |t)n^

[0145] Where t is the time parameter;

[0146] |ω b | is the angular velocity vector ω of the line of sight b The amplitude of

[0147] I is the identity matrix;

[0148] n is the angular velocity vector ω of the line of sight b direction;

[0149] n^ is the anti-multiplication matrix formed by n;

[0150] n T is the transpose of n.

[0151] Step 205: Estimate the aiming line of the over-the-top area based on the angle motion relationship equation at the time of over-the-top. The angle motion relationship equation at the time of over-the-top is specifically:

[0152]

[0153] Where, los bt The angle of the base system sight line at the moment of passing the top;

[0154] los bt (1) It is the projection of the base system’s sight line in the rolling direction at the moment of passing the top.

[0155] Solving the above equation yields the non-zero time parameter t, which can be used to estimate the base system's line of sight los in the overhead region. bt .

[0156] The basic principle of this step is that after the initial moment of the overhead area, t time has passed and the aiming line becomes los bt =C(t)los b0 If the position is out of the top area, then it should also meet the los bt (1)=η.

[0157] The two equations are combined and eliminated to form a transcendental equation for time t. This can be solved numerically using numerical methods or by using a universal formula to convert it into a quadratic algebraic equation with one variable to obtain an exact solution. The solution for t = 0 is the initial moment of entry into the over-the-top region and should be discarded.

[0158] Step 206: Calculate the roll frame angle of the over-the-top area based on the sight line of the over-the-top area. The steps for calculating the roll frame angle of the over-the-top area are:

[0159] First, calculate the roll frame angle of the first vertex based on the frame coupling relationship:

[0160] φ bt 1=-atan(los bt (2),los bt (3)

[0161] Next, calculate and φ bt 1 The second roll frame angle that passes the vertex is 180° different;

[0162]

[0163] Finally, φ bt 1.φ bt 2. Compared with the initial roll frame angle when entering the over-the-top area, the value with the smallest angle difference is used as the estimated roll frame angle of the over-the-top area.

[0164] The reason for calculating two roll frame angles in this step is that for roll-pitch type airborne photoelectric detection equipment, since the pitch frame can move in both positive and negative directions relative to 0 degrees straight ahead, the line of sight in the overhead area corresponds to two sets of roll and pitch frame angles, where the difference between the two roll frame angles is 180 degrees, and the corresponding pitch frame angles are opposite in sign. These two sets of roll and pitch frame angles can achieve the same line of sight. bt 1.φ bt 2. Compared with the roll frame angle when initially entering the over-the-top area, the value with the smallest angle difference is used as the estimated roll frame angle in the over-the-top area, which can minimize the roll frame rotation angle and ensure that the roll can rotate to the specified position at the fastest speed during high-speed over-the-top.

[0165] In step 207, the roll frame moves to the estimated exit overhead position and waits for the aiming line to exit the overhead area, and then proceeds to step 209. This step can use a direct closed-loop method to control the roll frame, and a speed feedforward method can be used according to the angle to ensure the rapid arrival of the roll frame.

[0166] In step 208, after the line of sight enters the overhead region, the stabilized platform tracks normally, but the roll frame is no longer slaved to the azimuth frame. The stabilized platform composed of the pitch frame and the azimuth frame performs closed-loop control based on the tracking image deviation. Because the unilateral overhead angle in the overhead region is not greater than the maximum misalignment angle of the stabilized platform and has a certain margin, even if the roll frame is not slaved to the azimuth frame, the stabilized platform can still track the target normally in the overhead region without hitting the limit.

[0167] Step 209, determine whether the aiming line has exited the overhead area. If so, proceed to step 210; otherwise, return to step 208, the roll frame maintains its position unchanged, and the stable platform continues to track the target.

[0168] Step 210 , after the aiming line of the airborne photoelectric detection device leaves the over-the-top area, the control strategy before entering the over-the-top area is restored, the roll frame is driven by the azimuth frame, and the process returns to step 201 to determine the next over-the-top area.

[0169] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A roll-pitch type airborne photoelectric detection equipment overhead tracking method, characterized in that: include: Step 1: In the tracking mode, determine whether the sighting line of the airborne photoelectric detection device enters the overhead area. If it enters the overhead area, execute step 2; otherwise, continue to execute step 1; Step 2: Calculate the initial aiming line and aiming line angular velocity when entering the overhead area based on the frame angle and frame angular velocity at the time of entering the overhead area; Step 3: Calculate the line of sight rotation matrix with time parameters according to the line of sight angular velocity; Step 4: Estimate the line of sight and roll frame angle in the over-the-top area based on the angular motion equation at the over-the-top moment. Step 5: The roll frame moves to the estimated exit position and waits for the aiming line to exit the overhead area. Step 6: After the line of sight enters the overhead area, the stabilized platform tracks normally, but the roll frame is no longer slaved to the azimuth frame; Step 7: After the sight line of the airborne photoelectric detection equipment leaves the over-the-top area, the roll frame is driven by the azimuth frame and returns to step 1 to determine the next over-the-top.

2. The overhead tracking method of a roll-pitch airborne photoelectric detection device according to claim 1, characterized in that: In step 1, the method for judging whether the aiming line of the airborne photoelectric detection device enters the overhead area is to compare the projection of the aiming line of the base system of the airborne photoelectric detection device in the rolling direction with the threshold value. When the size is greater than the threshold , the aiming line enters the overhead area, otherwise it is not in the overhead area.

3. The overhead tracking method of a roll-pitch airborne photoelectric detection device according to claim 2, characterized in that: The threshold It is related to the overhead angle range, specifically: Where, It is a single-sided vertical angle.

4. The overhead tracking method of a roll-pitch airborne photoelectric detection device according to claim 1, characterized in that: In step 2, the formula for calculating the initial aiming line when entering the overhead area is: Where, Initial sighting line when tying the base over the overhead area; The rotation matrix from the stable platform system to the base system is calculated based on the initial frame angle entering the overhead region; Tie the line of sight to stabilize the platform.

5. The overhead tracking method of a roll-pitch airborne photoelectric detection device according to claim 1, characterized in that: In step 2, the calculation formula of the angular velocity of the line of sight is: Where, 、 are the azimuth frame angle and angular velocity, respectively; 、 are the pitch frame angle and angular velocity, respectively; 、 are the roll frame angle and angular velocity, respectively.

6. The overhead tracking method of a roll-pitch airborne photoelectric detection device according to claim 1, characterized in that: In step 3, the calculation formula of the line of sight rotation matrix with time parameters is: Where, t is the time parameter; is the angular velocity vector of the line of sight The amplitude of is the identity matrix; is the angular velocity vector of the line of sight direction; for The anti-multiplication matrix formed; for The transpose of .

7. The overhead tracking method of a roll-pitch airborne photoelectric detection device according to claim 1, characterized in that: In step 4, the angular motion equation at the time of passing the top is specifically: Where, The aiming line of the base system is set for the moment of passing the top; for The component in the x-direction is the projection of the base system's sight line in the roll direction at the moment of passing the top; Solving the above equation yields a non-zero time parameter t , we can get the estimated line of sight of the base system in the overhead area by bringing back the equation ; Initial line of sight for the base when lacing over the overhead area.

8. The overhead tracking method of a roll-pitch airborne photoelectric detection device according to claim 1, characterized in that: In step 4, the steps to estimate the roll frame angle in the overhead area are: First, calculate the roll frame angle of the first vertex based on the frame coupling relationship: Where, They are the base system aiming lines at the moment of passing the top Components in the y and z directions; Secondly, calculate and The second roll frame angle out of the apex is 180° different; Finally, 、 Compared with the initial roll frame angle entering the over-the-top area, the value with the smallest angle difference is used as the estimated roll frame angle of the over-the-top area.

9. The overhead tracking method of a roll-pitch airborne photoelectric detection device according to claim 1, characterized in that: Before entering the over-the-top region, the stable platform formed by the pitch frame and the azimuth frame moves in a closed-loop according to the tracking deviation, and the roll frame is driven by the azimuth frame to maintain the azimuth frame angle close to zero degrees; after entering the over-the-top region, the roll frame moves toward the roll frame angle estimated to have exceeded the over-the-top region, and the stable platform formed by the pitch frame and the azimuth frame moves in a closed-loop according to the tracking deviation; after exiting the over-the-top region, the control strategy before entering the over-the-top region is restored.

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