Real-time calculation of ground targeting parameters using terrain elevation data

Abstract

A processor-based system of determining, in a moving aircraft, coordinates of a target, the system comprising a processing circuitry, the processor being operably connectable to a positioning system and a targeting system, the processor being configured to: receive, from the positioning system, data indicative of a current aircraft position; receive, from the targeting system, data indicative of a line-of-sight (LOS) vector from the cunent aircraft position to the target, and utilize a digital terrain elevation data (DTED) database to estimate a terrain point at which the received LOS vector meets a terrain surface location, thereby giving rise to data indicative of the coordinates of the target.

Description

[0001] REAL-TIME CALCULATION OF GROUND TARGETING PARAMETERS USING TERRAIN ELEVATION DATA

[0002] TECHNICAL FIELD

[0003] The presently disclosed subject matter relates to tactical targeting in aircraft, and in particular to real-time calculation of parameters for projectile release.

[0004] BACKGROUND

[0005] Problems of implementation of automation of tactical targeting by aircraft have been recognized in the conventional art and various techniques have been developed to provide solutions.

[0006] GENERAL DESCRIPTION

[0007] According to one aspect of the presently disclosed subject matter there is provided a system of determining, in a moving aircraft, coordinates of a target, the system comprising a processing circuitry, the processing circuitry being operably connectable to a positioning system and a targeting system, the processing circuitry being configured to: a) receive, from the positioning system, data indicative of a current aircraft position; b) receive, from the targeting system, data indicative of a line-of-sight (LOS) vector from the current aircraft position to the target, and c) utilize a digital terrain elevation data (DTED) database to estimate a terrain point at which the received LOS vector meets a terrain surface location, thereby giving rise to data indicative of the coordinates of the target. In addition to the above features, the system according to this aspect of the presently disclosed subject matter can comprise one or more of features (i) to (viii) listed below, in any desired combination or permutation which is technically possible:

[0008] (i) additionally comprising a targeting system, the targeting system being configured to provide the data indicative of LOS, wherein the data indicative of the LOS is derived from a pilot target selection.

[0009] (ii) the data indicative of LOS is derived from a pilot target selection on a head-up display (HUD).

[0010] (iii) the data indicative of LOS is derived from a pilot target selection on a helmetmounted display (HMD).

[0011] (iv) the processing circuitry being further configured to: d) compute a targeting time-to-release for a projectile carried by the moving aircraft, in accordance with, at least, a difference between the current aircraft altitude and an estimated terrain elevation indicated by the target coordinates.

[0012] (v) the processing circuitry is further configured to: repeat a) - d) for one or more additional iterations.

[0013] (vi) the processing circuitry is further configured to: prior to d), repeat a) - c) for one or more additional iterations.

[0014] (vii) he processing circuitry is configured to compute the targeting time-to-release in further accordance with one or more of: a) the current position of the aircraft, b) a roll of the aircraft, c) a pitch of the aircraft, d) a yaw of the aircraft, e) a velocity of the aircraft, f) an acceleration of the aircraft, g) a current atmospheric condition, h) a characteristic of the projectile, i) an ejection velocity of the projectile, and j) terrestrial coordinates of the target.

[0015] (viii) the processing circuitry is further configured to: responsive to an operator command, release the projectile in accordance with the computed targeting time-to-release.

[0016] According to another aspect of the presently disclosed subject matter there is provided a computer-implemented method of determining, in a moving aircraft, coordinates of a target, the method comprising: a) receiving, from a positioning system, data indicative of a current aircraft position; b) receiving, from a targeting system, data indicative of a line-of-sight (LOS) vector from the current aircraft position to the target, and c) utilizing a digital terrain elevation data (DTED) database to estimate a terrain point at which the received LOS vector meets a terrain surface location, thereby giving rise to data indicative of the coordinates of the target.

[0017] This aspect of the disclosed subject matter can further optionally comprise one or more of features (i) to (viii) listed above with respect to the system, mutatis mutandis, in any desired combination or permutation which is technically possible.

[0018] According to anothe aspect of the presently disclosed subject matter there is provided a computer program product comprising a computer readable non-transitory storage medium containing program instructions, which program instructions when read by a processor, cause the processing circuitry to perform a method of determining, in a moving aircraft, coordinates of a target, the method comprising: a) receiving, from a positioning system, data indicative of a current aircraft position; b) receiving, from a targeting system, data indicative of a line-of-sight (LOS) vector from the current aircraft position to the target, and c) utilizing a digital terrain elevation data (DTED) database to estimate a terrain point at which the received LOS vector meets a terrain surface location, thereby giving rise to data indicative of the coordinates of the target.

[0019] This aspect of the disclosed subject matter can further optionally comprise one or more of features (i) to (viii) listed above with respect to the system, mutatis mutandis, in any desired combination or permutation which is technically possible.

[0020] BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to understand the invention and to see how it can be carried out in practice, embodiments will be described, by way of non-limiting examples, with reference to the accompanying drawings, in which:

[0022] Fig. 1A illustrates an example prior art scenario of targeting by a radar-equipped aircraft;

[0023] Figs. 1B-1D illustrate progress of an airplane in the direction of a target, as well as related calculations performed by the aircraft’s on-board systems, in accordance with some embodiments of the presently disclosed subject matter;

[0024] Fig. 2 illustrates a logical block diagram of an example aircraft targeting system utilizing target coordinate determination and (optionally) projectile targeting based on DTED, in accordance with some embodiments of the presently disclosed subject matter; Fig. 3 illustrates an example logical representation of digital terrain elevation data, in accordance with some embodiments of the presently described subject matter;

[0025] Fig. 4A illustrates a flow diagram of an example method of determining target coordinates in a moving aircraft, utilizing a DTED, in accordance with some embodiments of the presently disclosed subject matter; and

[0026] Fig. 4B illustrates a flow diagram of an example method of utilizing determined target coordinates for projectile launch, in accordance with some embodiments of the presently disclosed subject matter.

[0027] DETAILED DESCRIPTION

[0028] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the presently disclosed subject matter may be practiced without these specific details. In other instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the presently disclosed subject matter.

[0029] Unless specifically stated otherwise, as apparent from the following discussions, it is appreciated that throughout the specification discussions utilizing terms such as "processing", "computing", "comparing", "determining", "calculating", “receiving”, “providing”, “obtaining”, “detecting” or the like, refer to the action(s) and / or process(es) of a computer that manipulate and / or transform data into other data, said data represented as physical, such as electronic, quantities and / or said data representing the physical objects. The term “computer” should be expansively construed to cover any kind of hardware-based electronic device with data processing capabilities including, by way of non-limiting example, the processing circuitry, processor, and modules therein disclosed in the present application.

[0030] The terms "non-transitory memory" and “non-transitory storage medium” used herein should be expansively construed to cover any volatile or non-volatile computer memory suitable to the presently disclosed subject matter. The operations in accordance with the teachings herein may be performed by a computer specially constructed for the desired purposes or by a general-purpose computer specially configured for the desired purpose by a computer program stored in a non- transitory computer-readable storage medium.

[0031] Embodiments of the presently disclosed subject matter are not described with reference to any particular programming language. It will be appreciated that a variety of programming languages may be used to implement the teachings of the presently disclosed subject matter as described herein.

[0032] Fig 1A illustrates an example prior art scenario of targeting by a radar-equipped aircraft.

[0033] Aircraft 160A transmits a radar pulse to target 140, and it computes a range-to- target (i.e. distance) from the returning pulse. Aircraft 160A can the compute relative altitude 110A from the range-to-target, to determine release time and release trajectory for a projectile aimed at the target.

[0034] Figs. 1B-1D illustrate progress of an airplane in the direction of a target, as well as related calculations performed by the aircraft’s on-board systems, in accordance with some embodiments of the presently disclosed subject matter.

[0035] In Fig. IB, aircraft 160B is flying above contoured terrain 150, at a particular clearance altitude 130B. Target 140 is located on the terrain 150 surface.

[0036] In Fig. 1C, the aircraft 160C has determined a line-of-sight 120C to target 140 (e.g. in response to the pilot selecting the target in an on-board targeting system. The aircraft on-board systems can identify a line-of-sight (LOS) 120C to the target, and then utilize digital terrain elevation data (DTED) to determine that line-of-sight 120C meets the terrain surface 150 at coordinates xl, yl, zl. The aircraft can then calculate its relative altitude HOC (i.e. relative to elevation of the target), and utilize the relative altitude HOC to determine a release time and release trajectory for a projectile aimed at the target. In Fig. ID, the aircraft 160D has moved closer to the target, and recalculated the LOS 120D. The new LOS 120D meets the terrain 150 at updated coordinates x2, y2, z2. The aircraft can then utilize updated relative altitude HOD to determine an updated release time and release trajectory for a projectile aimed at the target.

[0037] Attention is directed to Fig. 2, which illustrates a logical block diagram of an example aircraft targeting system utilizing target coordinate determination and (optionally) projectile targeting based on DTED, in accordance with some embodiments of the presently disclosed subject matter.

[0038] Positioning system 270 can be a suitable on-board system for tracking the position of the aircraft as it is moving. Positioning system 270 can utilize a global position system (GPS), inertial navigation system (INS), an attitude and heading reference system (AHRS), some combination of these, or some other suitable mechanism. In some embodiments, positioning system 270 provides data descriptive of the “six degrees of freedom” (i.e the six mechanical degrees of freedom of movement of a body in 3- dimensional space) and / or inertial data. Positioning system 270 can be operably connected to target tracking controller 210, and can, in some embodiments, supply target tracking controller 210 with e.g. current three-dimensional aircraft position data.

[0039] Targeting system 280 can be a suitable on-board system enabling a pilot to view and identify targets e.g. as a head-up display (HUD) or a helmet mounted system (HMS). In some examples, targeting system 280 can include an automated system that performs the targeting functions of the pilot. Targeting system 280 can utilize a processing circuitry comprising a processor and memory configured to determine a line-of-sight from the aircraft to the target (e.g. target selected by the pilot or automated system).

[0040] Positioning system 270 can be operably connected to target tracking controller 210, and can supply target tracking controller 210 with targeting information (e.g. data indicative of a line-of-sight vector from the aircraft to a ground target).

[0041] Optional radar system 290 can be suitable radar system that is suitable for targeting. Optional radar system 290, when present, can include control functionality for enabling / disabling radar targeting, such that when radar targeting is disabled, DTED- based targeting is enabled (and vice versa). In this manner, an aircraft can utilize radar targeting e.g. when stealth is not needed. Target tracking controller 210 can be operably connected to optional radar system 290.

[0042] Projectile time-to-launch controller 210 can be a system that controls release of a projectile such as an air-to-ground munition, or another type of air-to-ground payload. Projectile time-to-launch controller 210 can include processing circuitry 220, which in turn can include processor 230 and memory 240.

[0043] Processor 230 can be a suitable hardware-based electronic device with data processing capabilities, such as, for example, a general-purpose processor, digital signal processor (DSP), a specialized Application Specific Integrated Circuit (ASIC), one or more cores in a multicore processor, etc. Processor 230 can also consist, for example, of multiple processors, multiple ASICs, virtual processors, combinations thereof etc.

[0044] Memory 240 can be, for example, a suitable kind of volatile and / or non-volatile storage, and can include, for example, a single physical memory component or a plurality of physical memory components. Memory 240 can also include virtual memory. Memory 230 can be configured to, for example, store various data used in computation.

[0045] Processing circuitry 220 can be configured to execute several functional modules in accordance with computer-readable instructions implemented on a non-transitory computer-readable storage medium. Such functional modules are referred to hereinafter as comprised in the processing circuitry. These modules can include, for example, target coordinates determination unit 260, (optional) time-to-release calculation unit 250, (optional) projectile control unit 265, and digital terrain elevation data 255.

[0046] Projectile control unit 265 can be a functional module which performs, for example, the following functions: controlling actuators that change the exit trajectory of a releasable projectile controlling actuators that perform the release of the projectile

[0047] Target coordinates determination unit 260 can be a functional module which receives target line-of-sight (LOS) information from targeting system 280, and determines e.g. three-dimensional coordinates of the target using the LOS and digital terrain elevation data 255.

[0048] Time-to-release calculation unit 250 can be a functional module which - given target coordinate info - continually calculates the time-to-release and release trajectory for the projectile to reach its intended target.

[0049] Digital terrain elevation data (DTED) 255 as used herein refers to data indicative of a plurality of elevation values (e.g. relative to sea level or some other reference), wherein each elevation value is indicative of height of terrain in a particular geographic region.

[0050] An example DTED is described in detail below with reference to Fig. 3

[0051] Attention is now directed to Fig. 3, which illustrates an example logical representation of digital terrain elevation data, in accordance with some embodiments of the presently described subject matter.

[0052] Digital terrain elevation data (DTED) 300 can include data pertaining to a particular region on the earth’s surface. Accordingly, there can be geographical coordinates (e.g. longitude and / or latitude) associated with the edges of DTED. DTED 300 can have a width 320 (e.g. in the East-West axis) and length 310 (e.g. in the North- South axis).

[0053] By way of non-limiting example: a DTED 300 can describe a 10 km x 10 km area, and consist of a grid of 1000 x 1000 cells, where each cell pertains to a region of 10 meters x 10 meters.

[0054] A DTED 300 can include a group of cells (such as cell 330). Each cell can be associated with a particular geographic coordinate (e.g. longitude and latitude) denoting e.g. the position of the center of the cell or one of the corners of the cell. Each cell can be associated with a length and width e.g. a cell might pertain to a geographic square area of 10 meters x 10 meters, or 5 meters x 5 meters, or some other value. In FIG. 3, the cells containing dots denote additional undepicted cells. Each cell can be associated with a terrain elevation (e.g. in the example of FIG. 3 elevation value 340 of cell 330 is 20 meters, while elevation value 350 is 35 meters) i.e. a measurement of elevation (e.g. relative to sea level or some other reference elevation) of the terrain corresponding to the cell. In some embodiments, the terrain elevation of the cell denotes the highest elevation of the terrain in the cell. In some embodiments, the terrain elevation of the cell denotes the height of the terrain in the center of the cell. In some embodiments, the terrain elevation of the cell denotes an average height or some other data pertaining to the height of the terrain corresponding to the cell.

[0055] In some embodiments, the terrain elevation of the cell denotes the elevation including surface elements such as trees or buildings. In some embodiments, the terrain elevation of the cell denotes the elevation of the earth surface, without trees, buildings etc.

[0056] The cells of the geographic region represented in the DTED can be of various shapes and / or various sizes.

[0057] Attention is directed to Fig. 4A, which illustrates a flow diagram of an example method of determining target coordinates in a moving aircraft, utilizing a DTED, in accordance with some embodiments of the presently disclosed subject matter.

[0058] Processing circuitry 220 (e.g. target coordinates determination unit 260) can receive 400 a designation of a specific target.

[0059] In some embodiments, targeting is performed by a pilot who e.g. places or manipulates a pipper visible on a helmet-mounted display (HMD) or head up display (HUD) (which is e.g. part of targeting system 270) in order to select a particular target on the ground.

[0060] Processing circuitry 220 (e.g. target coordinates determination unit 260) can receive 410 aircraft position information (e.g. longitude, latitude, altitude etc.), as well as (optionally) other aircraft flight data relevant to targeting (e.g. current velocity and direction, aircraft roll / pitch / yaw, wind velocity, atmospheric temperature etc.). The aircraft position information can be received from e.g. positioning system 270, which in turn can derive the positioning info from GPS, INS, combination thereof, other suitable methods etc.

[0061] Processing circuitry 220 (e.g. target coordinates determination unit 260) can next receive 420 a line-of-sight vector from the aircraft to the selected target.

[0062] An LOS vector can be given - for example - as an azimuth and elevation.

[0063] In some embodiments, targeting system 270 comprises automated target selection functionality. In this case the target is selected automatically, and then targeting system 270 can supply the data indicative of the LOS vector to processing circuitry 220 (e.g. target coordinates determination unit 260).

[0064] Processing circuitry 220 (e.g. target coordinates determination unit 260) can use a DTED to determine 430 the coordinates and elevation of the location where LOS meets the earth.

[0065] For example, processing circuitry 220 (e.g. target coordinates determination unit 260) can utilize its current position (for example: given as longitude, latitude, altitude) and the LOS (given as azimuth and elevation angles) to determine a line toward the earth surface, and then utilize the elevation information of the DTED to determine the surface location where the line meets the earth. Processing circuitry 220 (e.g. target coordinates determination unit 260) can then determine coordinates (e.g. as longitude, latitude, altitude) of this surface location.

[0066] In some embodiments, aircraft systems then utilizes the target coordinates to launch a projectile at the target, as described below with reference to Fig. 4B.

[0067] In some embodiments, aircraft systems supplies the target coordinates to a guided projectile, which is then launched at the target.

[0068] In some embodiments, processing circuitry 220 performs the process of Fig. 4A (e.g. steps 410, 420, and 430) for additional iterations (e.g. as the aircraft approaches the target, thereby allowing processing circuitry 220 to determine more accurate target components). Attention is directed to Fig. 4B, which illustrates a flow diagram of an example method of utilizing determined target coordinates for projectile launch, in accordance with some embodiments of the presently disclosed subject matter.

[0069] Processing circuitry 220 (e.g. target coordinates determination unit 260) can compute 440 the current relative altitude of the aircraft i.e. the difference between the aircraft altitude as received from e.g. positioning system 270 (e.g. measured by an altimeter) and the altitude of the target as e.g. determined from the DTED as described above.

[0070] Processing circuitry 220 (e.g. time-to-release calculation unit 250) can perform 450 weapon release computation including e.g. calculation of a “target time-to-release” (e.g. as an absolute clock time, or as a future time offset given in milliseconds ) and associated projectile release trajectory - based on the relative altitude of the aircraft to the target and other parameters.

[0071] Computation of time-to-release and projectile release trajectory is known in the art of targeting. In addition to the relative elevation, parameters such as current velocity and direction, aircraft roll / pitch / yaw, wind velocity, and atmospheric temperature can be utilized in the computation of time-to-release and projectile release trajectory.

[0072] As described above with reference to Figs. 1B-1C, processing circuitry 220 (e.g. time-to-release calculation unit 250) can recompute the target location e.g. as the aircraft gets closer to the target. It can also recompute the relative elevation and / or time-to- release and / or projectile trajectory. Generally speaking: processing circuitry 220 (e.g. target coordinates determination unit 260) can update 460 the computation of target time- to-release zero or more times, subsequent to the initial computation.

[0073] In some embodiments, processing circuitry 220 (e.g. time-to-release calculation unit 250) recomputes the time-to-release and associated trajectory every 25-50 milliseconds.

[0074] Processing circuitry 220 (e.g projectile control unit 250) can then, in response to a launch command from a pilot or from an automated launching system, launch 470 a projectile in accordance with the computed target time-to-release. For example, processing circuitry 220 (e.g time-to-release calculation unit 250) can delay by a certain amount of time that is derived from the time-to-release, control the projectile trajectory, and then control a projectile release system to release the projectile at the time-to-release using the associated projectile trajectory.

[0075] In some examples, the pilot will command release of the projectile in a situation in which no time-to-release / projectile trajectory is available (for example due to obstacles between the aircraft and the target, or if the predicted trajectory would undershoot or overshoot the target). In such examples, processing circuitry 220 (e.g time-to-release calculation unit 250) can refrain from releasing the projectile commanded by the pilot.

[0076] It is to be understood that the invention is not limited in its application to the details set forth in the description contained herein or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Hence, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for designing other structures, methods, and systems for carrying out the several purposes of the presently disclosed subject matter.

[0077] It will also be understood that the system according to the invention may be, at least partly, implemented on a suitably programmed computer. Likewise, the invention contemplates a computer program being readable by a computer for executing the method of the invention. The invention further contemplates a non-transitory computer-readable memory tangibly embodying a program of instructions executable by the computer for executing the method of the invention.

[0078] Those skilled in the art will readily appreciate that various modifications and changes can be applied to the embodiments of the invention as hereinbefore described without departing from its scope, defined in and by the appended claims.

Claims

CLAIMS1. A system of determining, in a moving aircraft, coordinates of a target, the system comprising a processing circuitry, the processing circuitry being operably connectable to a positioning system and a targeting system, the processing circuitry being configured to: a) receive, from the positioning system, data indicative of a current aircraft position; b) receive, from the targeting system, data indicative of a line-of-sight (LOS) vector from the current aircraft position to the target, and c) utilize a digital terrain elevation data (DTED) database to estimate a terrain point at which the received LOS vector meets a terrain surface location, thereby giving rise to data indicative of the coordinates of the target.

2. The system of claim 1 , additionally comprising a targeting system, the targeting system being configured to provide the data indicative of LOS, wherein the data indicative of the LOS is derived from a pilot target selection.

3. The system of claim 2, wherein the data indicative of LOS is derived from a pilot target selection on a head-up display (HUD).

4. The system of claim 2, wherein the data indicative of LOS is derived from a pilot target selection on a helmet-mounted display (HMD).

5. The system of claim 1, the processing circuitry being further configured to: d) compute a targeting time-to-release for a projectile carried by the moving aircraft, in accordance with, at least, a difference between the currentaircraft altitude and an estimated terrain elevation indicated by the target coordinates.

6. The system of claim 4, wherein the processing circuitry is further configured to: repeat a) - d) for one or more additional iterations.

7. The system of claim 4, wherein the processing circuitry is further configured to: prior to d), repeat a) - c) for one or more additional iterations.

8. The system of claim 4, wherein the processing circuitry is configured to compute the targeting time-to-release in further accordance with one or more of: a) the current position of the aircraft, b) a roll of the aircraft, c) a pitch of the aircraft, d) a yaw of the aircraft, e) a velocity of the aircraft, f) an acceleration of the aircraft, g) a current atmospheric condition, h) a characteristic of the projectile, i) an ejection velocity of the projectile, and j) terrestrial coordinates of the target.

9. The system of claim 4, wherein the processing circuitry is further configured to: responsive to an operator command, release the projectile in accordance with the computed targeting time-to-release.

10. A processing circuitry-based method of determining, in a moving aircraft, coordinates of a target, the method comprising:a) receiving, from a positioning system, data indicative of a current aircraft position; b) receiving, from a targeting system, data indicative of a line-of-sight (LOS) vector from the current aircraft position to the target, and c) utilizing a digital terrain elevation data (DTED) database to estimate a terrain point at which the received LOS vector meets a terrain surface location, thereby giving rise to data indicative of the coordinates of the target. A computer program product comprising a computer readable non-transitory storage medium containing program instructions, which program instructions when read by a processor, cause the processing circuitry to perform a method of determining, in a moving aircraft, coordinates of a target, the method comprising: a) receiving, from a positioning system, data indicative of a current aircraft position; b) receiving, from a targeting system, data indicative of a line-of-sight (LOS) vector from the current aircraft position to the target, and c) utilizing a digital terrain elevation data (DTED) database to estimate a terrain point at which the received LOS vector meets a terrain surface location, thereby giving rise to data indicative of the coordinates of the target.

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