Visual surface symmetry aircraft BTT control method based on lateral SAR imaging seeker

Abstract

The invention discloses a plane symmetry aircraft BTT control method based on lateral SAR imaging seeker visibility, and the method comprises the steps: firstly overturning a projectile body by 180 degrees, enabling the available view field of a seeker to face downwards, and facilitating the finding of a target below; then designing a guidance instruction according to a lateral SAR imaging preposition angle requirement, carrying out amplitude limiting on a pitching guidance instruction, projecting the guidance instruction to a missile system, obtaining a roll angle increment instruction, and obtaining a roll angle instruction and a pitching overload control instruction by combining the roll angle increment instruction with a current roll angle; finally, after lateral SAR imaging is completed, a guidance instruction is calculated according to the requirement for hitting the target, and a roll angle instruction and a pitching overload control instruction are calculated according to the guidance instruction. According to the control method and the design method, the structure is universal, the engineering practice ability is high, and the method can be widely applied to various plane symmetry aircraft guidance control systems carrying lateral SAR imaging seekers in the future.

Description

Technical Field

[0001] The present invention belongs to the field of radar technology, and specifically relates to a BTT control method for a plane-symmetrical aircraft based on the visibility of a lateral SAR imaging seeker. Background Art

[0002] Synthetic aperture radar (SAR) is of great significance in battlefield reconnaissance and weapon guidance due to its advantages of all-day and all-weather coverage, and many aircraft are equipped with synthetic aperture radar seekers. The resolution of SAR imaging results is not affected by distance, and it has the advantage of long-distance imaging without reducing resolution. Uniform flight and positive side-view imaging are the best conditions for SAR imaging. In order to achieve better SAR imaging effects, windows can be opened on the side of the aircraft to create imaging conditions for the radar. However, due to the relatively flat head of the symmetrical aircraft, the wave penetration of the abdomen is poor, so that the seeker can only be imaged from the back, which seriously restricts the viewing angle of the seeker. At the same time, in order to meet the conditions for lateral imaging, the tilt-turn technology (BTT) needs to be used to adjust the aircraft to a suitable position, and it is necessary to ensure that the seeker can see the target throughout the process, which requires the matching design of the turning attitude angle and the field of view angle of the seeker. Summary of the invention

[0003] In order to overcome the shortcomings of the prior art, the present invention provides a BTT control method for a symmetrical aircraft based on the visual side SAR imaging seeker. First, the missile body is flipped 180 degrees so that the available field of view of the seeker is facing downward, which is convenient for finding the target below; then, the guidance instruction is designed according to the side SAR imaging lead angle requirement, and the pitch guidance instruction is limited, and the guidance instruction is projected under the missile system to obtain the roll angle increment instruction. The roll angle instruction and the pitch overload control instruction can be obtained in combination with the current roll angle; finally, after the side SAR imaging is completed, the guidance instruction is calculated according to the requirement of the strike target, and the roll angle instruction and the pitch overload control instruction are calculated according to the guidance instruction. The control method and design method of the present invention have a universal structure and strong engineering practice ability. In the future, they can be widely used in various types of symmetrical aircraft guidance control systems equipped with side SAR imaging seekers.

[0004] The technical solution adopted by the present invention to solve the technical problem includes the following steps:

[0005] Step 1: Flip the aircraft;

[0006] Set the roll channel roll angle command Set to 180° to flip the plane-symmetrical vehicle so that its back is facing downward, with the seeker head's available field of view partially aligned with the target;

[0007] Step 2: Design guidance instructions;

[0008] The front tilt angle is introduced into the yaw guidance command; the pitch guidance command adopts the modified proportional guidance to meet the terminal landing angle requirement:

[0009]

[0010] in: Overload command for pitch guidance; Overload command for yaw guidance; is the pitch sight angle; is the pitch line of sight angular velocity; The desired falling angle; for the remaining time; , is the pitch guidance proportional coefficient; is the yaw sight angle; is the ballistic deflection angle; The front tilt angle required for the seeker imaging; is the side-looking yaw guidance coefficient;

[0011] The pitch guidance overload command is limited. The pitch guidance overload command limit form is as follows:

[0012]

[0013] Step 3: Generate roll angle command and overload command;

[0014] The overload instruction calculated in step 2 , Projected to the missile system, the guidance overload instruction of the missile system is formed, that is,

[0015]

[0016] in: It is the pitch guidance overload instruction for the missile system; It is the overload instruction for yaw guidance in the missile system; is the projectile roll angle at the current moment;

[0017] The roll angle increment command is calculated using the guidance overload command under the missile system:

[0018]

[0019] According to the current rolling angle of the projectile , combined with the roll angle increment command , and get the roll angle command of the projectile in the relative inertial system:

[0020]

[0021] The missile pitch overload control command that needs to be implemented at this time for:

[0022]

[0023] Step 4: Determine the end time of lateral SAR imaging;

[0024] After the current oblique angle meets the working requirements of the seeker and maintains the set imaging time, the normal guidance instruction sign is determined. When the normal guidance instruction sign changes from positive to negative, the lateral maneuver is ended to make the aircraft fly over the target; at this time, proportional guidance is used in both pitch and yaw directions:

[0025]

[0026] in is the yaw line of sight angular velocity; is the yaw proportional guidance coefficient;

[0027] Step 5: Repeat step 3 to generate the roll angle command and overload command after the side SAR imaging is completed.

[0028] The beneficial effects of the present invention are as follows:

[0029] The method of the invention effectively ensures the full-range visibility of the seeker and meets the requirements of the aircraft guidance control system. The method has broad prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The figure is a flow chart of the method of the present invention.

[0031] Figure 2 This is a roll angle command comparison curve according to an embodiment of the present invention.

[0032] Figure 3 This is a comparison curve of the beam pitch scanning range of an embodiment of the present invention.

[0033] Figure 4 This is a comparison curve of the beam yaw scanning range of an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0035] In order to solve the problem that the traditional BTT control method of a plane-symmetrical aircraft is prone to cause the seeker to be unable to find the target when equipped with a side SAR imaging seeker, it is necessary to make simple, universal and effective improvements to the BTT control method to ensure that the seeker is visible throughout the entire process. The present invention provides a BTT control method for a plane-symmetrical aircraft based on the visibility of the side SAR imaging seeker. In order to ensure that the seeker is visible throughout the entire process when working, the roll angle command calculation is converted into a relative roll command calculation, and through the design of the guidance command, the side SAR imaging meets the front tilt angle requirement and the pitch direction guidance command symbol is combined to determine the time to end the lateral maneuver, thereby achieving the matching of the control system of the plane-symmetrical aircraft and the requirements of the seeker.

[0036] like Figure 1 As shown, a BTT control method for a plane-symmetric aircraft based on the visibility of a side-view SAR imaging seeker comprises the following steps:

[0037] Step 1, flip the aircraft;

[0038] Since the belly of a plane-symmetrical aircraft has poor wave penetration, the scope of use of the seeker is limited. In order to fully utilize the available field of view of the seeker, it is necessary to align the available field of view of the seeker with the target, that is, the aircraft needs to face downward. Therefore, the roll channel roll angle command Set it to 180° to flip the projectile.

[0039] Step 2: Design guidance instructions;

[0040] Since the front tilt angle requirement needs to be met when performing side-looking SAR imaging, the front tilt angle can be introduced into the yaw guidance command; in order to meet the terminal landing angle requirement, the pitch guidance command can use modified proportional guidance.

[0041]

[0042] in: Overload command for pitch guidance; Overload command for yaw guidance; is the pitch sight angle; is the pitch line of sight angular velocity; The desired falling angle; for the remaining time; , is the pitch guidance proportional coefficient; is the yaw sight angle; is the ballistic deflection angle; The front tilt angle required for the seeker imaging; is the side-looking yaw guidance coefficient;

[0043] In order to avoid the problem of singularity and frequent changes in polarity of the roll angle command, the pitch guidance command needs to be limited. The pitch guidance command limiting form is as follows:

[0044]

[0045] Step 3: Generate roll angle command and overload command.

[0046] The guidance command calculated in step 2 , Projected onto the missile system, the guidance instructions are formed. That is:

[0047]

[0048] in: It is the pitch guidance overload instruction for the missile system; It is the overload instruction for yaw guidance in the missile system;

[0049] Use the guidance command of the missile body to calculate the roll angle increment command:

[0050]

[0051] According to the current rolling angle of the projectile , combined with the roll angle increment command , then the missile body roll angle command in the relative inertial system can be obtained:

[0052]

[0053] The missile pitch overload control command that needs to be implemented at this time for:

[0054]

[0055] Step 4: Determine the end time of lateral SAR imaging;

[0056] The lateral maneuver can be ended after the current tilt angle meets the working requirements of the seeker and maintains sufficient imaging time. However, in order to ensure the continuity of the roll angle command and avoid the roll angle command jumping, which causes the seeker to lose the target, it is also necessary to judge the sign of the normal guidance command. When the sign of the normal guidance command changes from positive to negative, the lateral maneuver can be ended and the aircraft can fly over the target. At this time, proportional guidance can be used in the pitch and yaw directions.

[0057]

[0058] in is the yaw line of sight angular velocity; is the yaw proportional guidance coefficient;

[0059] Step 5: Same as step 3, the roll angle command and overload command are generated after the lateral SAR imaging is completed.

[0060] Example:

[0061] The invention is further described in conjunction with a symmetrical aircraft calculation example. The aircraft has an initial altitude of 37 km and is 120 km from the target. The maximum working distance of the synthetic aperture radar is 55 km, and the front tilt angle must be 10°, the imaging time must be 1 s, and the beam must be pitched and scanned. Range ±40°, beam yaw scanning Range ±40°.

[0062] Step 1, flip the aircraft;

[0063] To make the aircraft stable and back-down, set the roll channel roll angle command Set it to 180°, and set the transition process to make the missile body flip. The integrated roll channel roll angle command is:

[0064]

[0065] in For flight time.

[0066] Step 2: Design guidance instructions;

[0067] In order to meet the requirement of 10° front tilt angle, the 10° front tilt angle can be introduced into the yaw guidance command and selected ; The terminal landing angle requirement is -85°, so the guidance command is:

[0068]

[0069] In order to avoid the problem of singularity and frequent changes in polarity of the roll angle command, the pitch guidance command needs to be limited. The pitch guidance command limiting form is as follows:

[0070]

[0071] Step 3: generating a roll angle command and an overload command;

[0072] The guidance command calculated in step 2 , Projected onto the missile system, the guidance instructions are formed. That is:

[0073]

[0074] Use the guidance command of the missile body to calculate the roll angle increment command:

[0075]

[0076] According to the current rolling angle of the projectile , combined with the roll angle increment command , then the missile body roll angle command in the relative inertial system can be obtained:

[0077]

[0078] The missile pitch overload control command that needs to be implemented at this time for:

[0079]

[0080] Step 4: Determine the end time of lateral SAR imaging;

[0081] When the current tilt angle reaches 10° and remains for 1 second, the imaging is considered complete. At this time, the normal guidance instruction sign is determined. When the normal guidance instruction sign changes from positive to negative, the lateral maneuver can be ended, allowing the aircraft to fly over the target. At this time, proportional guidance can be used in both pitch and yaw directions. Select .

[0082]

[0083] Step 5: Same as step 3, the roll angle command and overload command are generated after the lateral SAR imaging is completed.

[0084] In order to verify the performance of the present invention, the BTT allocation method proposed by the present invention and the traditional BTT control method were simulated respectively. Figure 2~Figure 4 From the simulation results, it can be seen that the BTT control method designed in the present invention can make full use of the maneuverability of the missile body, while ensuring that the seeker beam angle is within the available range, achieving full-range visual target.

Claims

1. A BTT control method for a symmetrical aircraft based on the visual aspect of a lateral SAR imaging seeker, characterized in that: The steps include: Step 1: Flip the aircraft; Set the roll channel roll angle command Set to 180° to flip the plane-symmetrical vehicle so that its back is facing downward, with the seeker head's available field of view partially aligned with the target; Step 2: Design guidance instructions; The front tilt angle is introduced into the yaw guidance command; the pitch guidance command adopts the modified proportional guidance to meet the terminal landing angle requirement: ； in: Overload command for pitch guidance; Overload command for yaw guidance; is the pitch sight angle; is the pitch line of sight angular velocity; The desired falling angle; for the remaining time; , is the pitch guidance proportional coefficient; is the yaw sight angle; is the ballistic deflection angle; The front tilt angle required for the seeker imaging; is the side-looking yaw guidance coefficient; The pitch guidance overload command is limited. The pitch guidance overload command limit form is as follows: ； Step 3: Generate roll angle command and overload command; The overload instruction calculated in step 2 , Projected to the missile system, the guidance overload instruction of the missile system is formed, that is, ； in: It is the pitch guidance overload instruction for the missile system; It is the overload instruction for the yaw guidance of the missile system; is the projectile roll angle at the current moment; The roll angle increment command is calculated using the guidance overload command under the missile system: ； According to the current rolling angle of the projectile , combined with the roll angle increment command , and get the roll angle command of the projectile in the relative inertial system: ； The missile pitch overload control command that needs to be implemented at this time for: ； Step 4: Determine the end time of lateral SAR imaging; After the current oblique angle meets the working requirements of the seeker and maintains the set imaging time, the normal guidance instruction sign is determined. When the normal guidance instruction sign changes from positive to negative, the lateral maneuver is ended to make the aircraft fly over the target; at this time, proportional guidance is used in both pitch and yaw directions: ； in is the yaw line of sight angular velocity; is the yaw proportional guidance coefficient; Step 5: Repeat step 3 to generate the roll angle command and overload command after the side SAR imaging is completed.

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