Method for judging field of view of sunlight incident seeker

Abstract

The invention relates to the military field, in particular to a method for judging the view field of a solar ray incident seeker. The method provided by the invention can be used for judging whether the direct solar light and the reflected solar light can enter the laser guided weapon seeker or not in a marine environment, and provides a theoretical basis and guidance for the scheme design of a laser guided weapon combat environment test. And the laser guided weapon putting precision is ensured.

Description

Technical Field

[0001] The present invention relates to the military field, and particularly to a method for discriminating the incidence of sunlight into the field of view of a seeker. Background Art

[0002] A laser-guided bomb is a bomb that uses laser guidance technology for precise strikes. It generally consists of a laser seeker (seeker), a control device, and a warhead. The working principle of a laser-guided bomb: First, an airborne laser illuminator (electro-optical pod) or a ground illuminator is used to irradiate the target with laser light. Then, the seeker receives the laser signal reflected from the target, generates a guidance command based on the relative position relationship between the bomb and the target at the current moment, and adjusts the attitude to achieve flight control. Finally, the warhead of the laser-guided bomb explodes near the target to destroy the target. As a bomb that uses a laser seeker to accurately locate the target, laser irradiation is a necessary condition for its combat use. However, due to the complexity and uncertainty of the battlefield environment, the combat performance of laser-guided weapons is greatly affected. The following main factors are considered during the current combat use process: 1. Meteorological conditions: The meteorological environment has a great impact on the accuracy of laser guidance. Under weather conditions such as heavy rain, haze, and snow, the laser beam is easily scattered and absorbed, resulting in the formation of false targets in the air, causing laser-guided weapons to be deflected, the ballistic range to be lengthened, and the guidance accuracy to decrease. Under strong wind conditions, it will also affect the flight trajectory of laser-guided bombs.

[0003] 2. Lighting conditions: Generally, a laser-guided bomb needs to receive a laser beam to perform guidance. Therefore, the lighting conditions also have a great impact on the guidance accuracy of laser-guided bombs. At night or in a dark environment, the propagation distance of the laser beam will be farther. However, under sunlight or strong light irradiation, the laser beam is easily reflected and refracted, resulting in a decrease in guidance accuracy. Especially when the sunlight directly enters the inside of the seeker, it causes a light saturation phenomenon inside the seeker. At this time, it is difficult for the seeker to receive the echo energy of the laser spot, thus losing the guidance function.

[0004] 3. Terrain conditions: The actual battlefield environment is complex, with changes in terrain height. In mountainous areas or urban areas with high-rise buildings, the laser beam is easily blocked and reflected, resulting in the seeker's misjudgment of the relative position relationship between the bomb and the target, and then generating incorrect guidance commands and flight trajectories.

[0005] 4. Electronic countermeasures: During the actual confrontation between the two sides, the enemy may use electronic interference equipment to interfere with the guidance system of laser-guided bombs, resulting in a decrease in guidance accuracy.

[0006] The seeker is highly sensitive to sunlight. For weapons equipped with optical seekers, this has been taken into account in terms of the trajectory and weapon attitude changes during the design phase, so as to avoid the "malfunction" of the seeker caused by direct sunlight during use. However, in the marine environment, in addition to direct sunlight, the way sunlight enters the seeker also includes the reflection on the sea surface, namely fish-scale light. After the reflected light enters the seeker, it will cause the same effect as direct sunlight. Therefore, during the use of laser-guided weapons, judging whether the sunlight can be reflected into the seeker in the marine environment is an important prerequisite for ensuring the delivery accuracy of laser-guided weapons. Summary of the Invention

[0007] The present invention discloses a method for discriminating the incident field of view of sunlight on a seeker. By means of theoretical modeling, the reception state of the seeker for sunlight at each position on the trajectory is calculated in a timely manner, providing a theoretical basis and guidance for the scheme of the combat environment test of laser-guided weapons.

[0008] The present invention provides a method for discriminating the incident field of view of sunlight on a seeker, including the following steps: S1. Obtain trajectory data; S2. Solve the attitude of the seeker's field of view; S3. Solve the pointing vector of the seeker; S4. Solve the angles between the pointing vector of the seeker and the incident and reflected light rays; S5. Discriminate the conditions for sunlight to enter the field of view of the seeker.

[0009] According to the method for discriminating the incident field of view of sunlight on a seeker provided by the present invention, the trajectory data in S1 includes the attitude angle of the laser-guided bomb, the position coordinates of the laser-guided bomb, and for the seeker projectile type with a frame, the elevation angle of the seeker frame and the pitch angle of the seeker frame also need to be obtained.

[0010] According to the method for discriminating the incident field of view of sunlight on a seeker provided by the present invention, the attitude of the seeker's field of view in S2 includes the elevation angle of the seeker ρ g and the azimuth angle of the seeker ρ f。

[0011] According to the method for discriminating the incident field of view of sunlight on a seeker provided by the present invention, when the seeker adopted by the laser-guided bomb is a vane head, the ρ g is the trajectory inclination angle ψ V , the ρ f is the trajectory deviation angle θ 1b ; When the seeker used by a laser-guided bomb is a non-vane seeker, the ρ g is a non-vane seeker G d and the ρ f is a non-vane seeker F w .

[0012] According to the method for determining the incident field of view of the sun's rays on the seeker provided by the present invention, the , where ψ is the yaw angle of the bomb, β is the sideslip angle of the bomb.

[0013] According to the method for determining the incident field of view of the sun's rays on the seeker provided by the present invention, the , where φ is the pitch angle of the bomb, α is the angle of attack of the bomb.

[0014] According to the method for determining the incident field of view of the sun's rays on the seeker provided by the present invention, the coordinate form of the seeker pointing vector Vector Xb in S3 is:

[0015] where L is the unit vector of the seeker pointing.

[0016] According to the method for determining the incident field of view of the sun's rays on the seeker provided by the present invention, the condition for determining that the sun's rays enter the seeker's field of view in S5 is: , where γ is the roll angle of the laser-guided bomb.

[0017] The present invention has the following advantages compared with the prior art: The method for determining the incident field of view of the sun's rays on the seeker provided by the present invention can be used to determine whether the direct sunlight and the reflected sunlight can enter the seeker of the laser-guided weapon in the marine environment, providing a theoretical basis and guidance for the scheme design of the combat environment test of the laser-guided weapon, and ensuring the dropping accuracy of the laser-guided weapon. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 shows the relative relationship between the seeker and the projectile body; Figure 2 is a schematic diagram of the dropping of a laser-guided weapon; Figure 3 is a schematic diagram of the sun's rays irradiating; Figure 4 Schematic diagram of light received by the seeker Specific implementation manners

[0019] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] The following combines Figures 1 - 4 the embodiments shown below to describe the technical solutions of the present invention: The present invention provides a method for discriminating the incident of sunlight on the field of view of a seeker. The method is used to discriminate whether sunlight can enter the field of view at each position on the trajectory of a laser-guided weapon. The method includes the following steps: S1. Acquisition of trajectory data; The acquisition of trajectory data can be carried out by means of a simulation program corresponding to the missile type or the data information obtained through telemetry. The types of data should include the attitude angles (pitch angle, yaw angle and roll angle) of the laser-guided bomb, the position coordinates of the laser-guided bomb. For the seeker missile type with a frame, the elevation angle of the seeker frame and the pitch angle of the seeker frame also need to be obtained.

[0021] S2. Solving the attitude of the seeker field of view; The seeker of the laser-guided bomb and the bomb body are mechanically connected to jointly form a laser-guided bomb. During the combat use of the laser-guided bomb, the seeker determines the relative relationship between the missile and the target by capturing the position of the spot irradiated by the optoelectronic pod, so as to guide the laser-guided bomb to attack the target. Therefore, from a mechanical point of view, a two-rigid-body system is formed between the seeker and the bomb body. The problem of the seeker pointing needs to establish a translation coordinate system at the current position of the laser-guided bomb, and determine its pointing according to the characteristics of different types of seekers. Let the ground coordinate system where the seeker of the laser-guided bomb is located be denoted as O xyz , where O x is the due north direction, O z is the due east direction, O y is the sky direction, L is the unit vector of the seeker pointing.

[0022] When the seeker adopted by the laser-guided bomb is a vane seeker, its pointing is consistent with the direction of the bomb body speed. Therefore, the angle for determining its azimuth is the ballistic inclination angle ψ v and the ballistic deflection angleθ 1b 。

[0023] Considering the laser-guided bomb with precision guidance, its ballistic plane is basically in the vertical plane, and the calculation formulas for its ballistic inclination angle and ballistic deflection angle can be obtained by using a simplified calculation method: (1) (2) Wherein, φ is the pitch angle of the bomb, ψ is the yaw angle of the bomb, α is the angle of attack of the bomb, β is the sideslip angle of the bomb.

[0024] When the seeker of the laser-guided bomb is not a vane seeker, for most laser-guided bombs, the seeker is located inside the frame connected to the bomb body, and there is a coordinate transformation relationship between the seeker and the bomb body, which needs to be obtained according to the matrix relationship: (3) Wherein, (4) (5) (6) (7) (8) Where k jgd and k jfw respectively represent the elevation angle of the seeker frame and the pitch angle of the seeker frame of the GGG laser-guided bomb, γ is the roll angle of the laser-guided bomb, then according to the above matrix multiplication relationship, the elevation angle of the seeker and the azimuth angle of the seeker can be expressed as: (9) (10) Let the attitude angle of the seeker field of view be ρ g 、 ρ f ,where ρ g is the elevation angle of the seeker, ρ f is the azimuth angle of the seeker, then it can be expressed as: (11) (12) S3. Calculate the seeker pointing vector; During the delivery of a laser-guided bomb, the geometric dimensions of the bomb body can be ignored compared to its ballistic altitude and range. Therefore, in the calculation and analysis, the current position of the bomb body can represent the current position of the seeker. As Figure 2 shown, let the position of the target be the origin of the coordinate system O (0, 0, 0), the due north direction be the x-axis, the due east direction be the z-axis, and the xyz form the current laser-guided bomb in the target coordinate system according to the right-hand coordinate system. Then the starting point of the seeker pointing vector is the coordinate of the selected ballistic point, which can be expressed as: (13) where TX n1b , TZ n1b and TY n1b are the current position coordinates of the laser-guided bomb respectively; The calculation formula for the seeker pointing point can be expressed as: (14) (15) (16) Then the coordinate form of the seeker pointing vector can be expressed as: (17) S4. Calculate the angles between the seeker pointing vector and the incident and reflected light rays; Let the coordinates at a certain point on the ballistic be s ( x 0 ，y 0 ，z 0 ), s the coordinate of the reflection position of the sun on the water surface at the position be s ʹ( x r ，0，z r ), the seeker axis vector be n ( i, j, k ), the seeker field of view angle be α , the solar altitude angle be θ s , then the seeker, the sun ray, and the sun reflection are abstracted into the geometric models as shown in Figure 3 and 4 shown. For the convenience of mathematical modeling and calculation, it is assumed here that the sun ray emits from the seeker position. Then there are the following vector relationships: (18) (19) Let N be OP the unit vector in the OAʹ direction, then (20) (21) Using the above formula, the normal vector of the ground plane can be expressed as: (22) The reflected light vector can be expressed as: (23) Therefore, the angle between the incident light and the seeker pointing vector can be expressed as (in the case of direct sunlight): (24) The straight-line distance between the solar reflection and the projection point of the seeker on the ground: (25) Then AO the angle between the vector and the seeker pointing vector is (in the case of solar reflection): S5. Determine the condition for the sun pipeline to enter the seeker's field of view; When both direct sunlight and reflection of sunlight will affect the laser-guided bomb, the seeker will be affected by sunlight and should meet the following conditions: (27) The above is only a preferred embodiment of this example, and does not impose any limitation on this example. Any simple modification, change, and equivalent change made to the above example according to the technical essence of the invention still fall within the protection scope of the technical solution of this example.

Claims

1. A discriminant method for the sun ray incident on the seeker field of view, characterized in that It includes the following steps: S1. Obtain ballistic data; S2. Solve the attitude of the seeker's field of view; S3. Solve the pointing vector of the seeker; S4. Solve the angles between the seeker's pointing vector and the incident and reflected light rays; S5. Determine the conditions for the sun's rays to enter the seeker's field of view.

2. The discriminant method for the field of view of the solar ray incident seeker according to claim 1, characterized in that, The ballistic data described in S1 includes the attitude angle of the laser-guided bomb, the position coordinates of the laser-guided bomb, and for the seeker projectile type with a frame, it is also necessary to obtain the elevation angle of the seeker frame and the pitch angle of the seeker frame.

3. The discrimination method of the sun ray incident guiding head field of view according to claim 1, characterized in that The seeker field-of-view attitude described in S2 includes the elevation angle of the seeker ρ g and the azimuth angle ρ of the seeker f .

4. The discriminant method for the field of view of a solar ray incident seeker according to claim 3, wherein, When the seeker used by a laser-guided bomb is a vane seeker, the ρ g is the ballistic inclination angle ψV, and the ρ f is the ballistic deflection angle θ 1b ; When the seeker used in a laser-guided bomb is a non-weathercock seeker, the ρ g is a non-weathercock seeker G d , the ρ f is a non-weathercock seeker F w .

5. The discriminant method for the field of view of a solar ray incident seeker according to claim 4, characterized in that, The said , wherein ψ is the bomb yaw angle β is the bomb sideslip angle 6. The discriminant method for the field of view of the solar ray incident seeker according to claim 4, characterized in that, The said , wherein φ is the pitch angle of the bomb, α is the angle of attack of the bomb.

7. The discriminant method for the field of view of the solar ray incident seeker according to claim 6, wherein, The seeker pointing vector described in S3 Vector Xb has the following coordinate form: ， Among them, L is the seeker pointing unit vector.

8. A discriminant method for the sun ray incident guiding head field of view as described in claim 7, characterized in that, The conditions for determining that the sun's rays enter the seeker's field of view described in S5 are: ， Among them, γ is the roll angle of the laser-guided bomb.

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