COORDINATED SEARCH OF AIRSPACE

Description

AREA OF INVENTION

[0001] The present invention relates to a method for searching a search area, a missile and a missile formation. BACKGROUND OF THE INVENTION

[0002] Modern aircraft are usually equipped with a large number of sensors, which play an important role for the aircraft and / or the pilot in order to carry out a mission with the best possible result.

[0003] One such sensor is radar, which is also one of the most widely used sensors for situational awareness. Radar can detect objects or targets at long ranges. The performance of radar is less affected by weather than, for example, a camera sensor. Target detection / tracking using radar is still possible even when it is no longer possible with imaging electro-optical or infrared sensors due to IMC (Instrument Meteorological Conditions).

[0004] Aircraft were often equipped with mechanically swiveling radar antennas. This meant that airspace scanning could be performed with a few parameters that could be optimized. Typically, the pilot defines the airspace to be scanned, usually as an angle and half-width, and the range within which a target of a defined size should be detected. Based on this information, the radar then optimizes the transmitted waveform. With this approach, the search pattern and airspace scanning are largely fixed and depend only on the size of the airspace being scanned.

[0005] US 2006 / 0114324A1 describes a monitoring procedure comprising the following steps: sending information requests to one or more of a plurality of unmanned aerial platforms, each carrying one or more sensors for collecting information; coordinating the processing of the requests among the plurality of aerial platforms; and transmitting responses to the requests to one or more requesters. A monitoring system that can be used to carry out the procedure is also described. SUMMARY OF THE INVENTION

[0006] One object of the present invention is to improve the searching of an airspace in such a way that fast and efficient situational awareness can be ensured, for example for a pilot.

[0007] This problem is solved by a method, a missile, and a missile formation according to one of the independent claims. It should be noted that the following described aspects apply to the method, the missile, and the missile formation.

[0008] According to the invention, a method for searching a search area is provided, wherein at least one radar is arranged in at least two missiles. The method comprises: a) dividing the search area into at least two sub-search areas, b) searching the at least two sub-search areas with the respective radar of the at least two missiles, wherein the at least two missiles perform the search cooperatively, and wherein the sub-search areas are selected such that the overall search time is minimal.

[0009] A radar is designed to detect various objects. In particular, the radar can scan a search area, which is usually a volume of air. According to the invention, a search area is scanned in such a way that objects or targets can be detected with a predetermined, selectable, or adjustable probability of detection. In other words, the probability that undetected targets or objects remain in the search area after scanning is very low; as few targets or objects as possible remain undetected. This scanning is of utmost importance, for example, for situational awareness by a pilot. Undetected objects or targets can become a problem not only because of potential hostility during a mission, but also because of a possible collision risk in the airspace. Situational awareness refers to the determination of the location or...the speed of other targets or objects.

[0010] Radar sensors, also referred to simply as radar in this text, are sensors that a missile may have, along with other sensors such as a camera. Such a radar can be equipped with active electronic control of its individual elements (in English: active electronically scanned array antennas (AESA)). This type of radar can control the radar beam almost instantaneously for different solid angles (a solid angle is defined as horizontal and vertical angles, also called azimuth and elevation), thus enabling adaptive beam steering.

[0011] A flying object encompasses any type of flying device with any type of propulsion. For example, airplanes, unmanned aerial vehicles (UAVs), drones, guided missiles, rockets, or helicopters.

[0012] The search effort to detect an object or target within the search area of ​​two or more missiles is carried out cooperatively. This means that a coordinated search of the search area takes place.

[0013] The search area is a volume of air that can be detected by at least one radar of the respective missile. The search area can be specified using horizontal and vertical angles. It is also possible to specify the search area using three-dimensional coordinates.

[0014] Often, the missiles are in flight formation within the airspace they are traversing. The search area will, for example, be located in the vicinity of both missiles. Preferably, the search area will be positioned ahead of the missiles in the direction of flight.

[0015] The area to be searched in the airspace, i.e., the search area for the missiles, is divided into at least two sub-search areas. In some examples of the invention, the number of sub-search areas corresponds to the number of missiles. The search of the at least two sub-search areas is carried out by the respective radar of each missile, with each missile searching at least one sub-search area.

[0016] Searching the sub-search areas or the search area as a whole is a cooperative search. The search effort is distributed so that the same parts of the search area do not need to be searched more than once. For example, with two missiles, each equipped with a radar, the search area is divided into two sub-search areas. Both missiles search their respective sub-search areas simultaneously or essentially simultaneously. In some examples, this procedure is carried out by at least two missiles in flight.

[0017] The partial search areas are selected to minimize the overall search time. This ensures that the optimal division of the search area is found and that multiple searches of the same area are avoided. The search area is searched in the fastest possible time, thus saving time when searching a three-dimensional volume of air, which may also be specified by the pilot. The method according to the invention avoids delays in searching a search area, which can occur, for example, when the search area is divided in a naive manner, such as into equal parts. This is particularly relevant when the search area extends across arbitrary horizontal and vertical angles in the airspace. In some examples of the method, the total search time is the cooperative total search time required by the at least two aircraft to search the area.

[0018] For example, the total search time is the maximum of the search times for the corresponding sub-search areas. For instance, the search times for different divisions of the search area into sub-search areas can be measured, and the maximum search time can thus be determined. For a specific division of the search area into sub-search areas, the total search time is minimal. The search time is the time the radar beam needs to illuminate the sub-search area and receive the echo. In some examples, the time required to process the received signal (echo) in order to detect objects or targets is also taken into account.

[0019] For example, the probability of detecting an object within the search area can be specified or predefined. The pilot, for instance, can specify the probability of detection. If necessary, this probability can be changed or adjusted to the specific situational awareness.

[0020] In one example, the sub-search areas essentially do not overlap. In some examples, the sub-search areas do not overlap at all. This simplifies search coordination and reduces the need for communication between missiles. There are also examples where the sub-search areas overlap minimally. Minimal or no overlap avoids multiple searches of a (sub)area and minimizes the search effort required to cover a search area. It also prevents gaps in the search area while simultaneously minimizing the overall search time.

[0021] As one example shows, the search area can be predefined or modified. For instance, the pilot can specify the search area by setting a horizontal or vertical angle and the corresponding half-width (also referred to as half-width in azimuth and elevation). If necessary, the search area can be adapted to the specific situational awareness system. In some examples, the search area is predefined.

[0022] According to one example, the division of the search area into sub-search areas changes according to the movement and / or trajectory of the at least two missiles.

[0023] According to the invention, the search area is continuously divided into sub-search areas according to the movement and / or trajectory of the at least two missiles. The search area is defined, for example, by means of three-dimensional coordinates. The missiles move within the search area, causing the horizontal and vertical angles (azimuth and elevation angles) and their angular amplitudes to change.

[0024] For example, a minimum probability of detecting an object of a given size at a given distance is guaranteed. This serves to enhance situational awareness, so that, for instance, the pilot can be informed how thoroughly the search area has been covered.

[0025] For example, a sub-search area can be defined according to a horizontal angle, a vertical angle and their corresponding angular widths, or according to three-dimensional coordinates. All sub-search areas can also be defined based on horizontal and vertical angles. In some examples, defining one or more sub-search areas using three-dimensional coordinates is possible; for instance, the corner points or the area of ​​the sub-search area are specified.

[0026] In one example, one of at least two missiles assigns the search area to be searched to at least one other missile. This allows for centralized control of the process. The assignment can be performed by any of the missiles. In some examples, one of the missiles is specifically designated for this purpose. Centralized control optimizes the search effort.

[0027] According to one example, at least two missiles independently define the sub-search area to be searched by their radar. This independent assignment of the search area by each missile creates a decentralized control system. The search area assigned to itself by an individual missile can be identical to the sub-search area if the search area is divided into different sub-search areas by a single missile using a central control system.

[0028] According to one aspect of the invention, a missile is provided which comprises at least one radar and a processing unit. The processing unit is configured to carry out the method according to the invention.

[0029] According to one aspect of the invention, a missile formation is provided which comprises at least two missiles, wherein the missile formation is configured to cover a search area in an airspace.

[0030] According to one aspect of the invention, the coordinated search of a search area with at least two missiles, each containing at least one radar, is highly advantageous. In particular, the method results in time savings when searching a three-dimensional search area. If the search area lies at arbitrarily defined azimuth and elevation angles (horizontal and vertical angles) and their corresponding angular widths, then a simple division of the search area, as in the prior art, for example, halving the search area, leads to significant time delays in the overall search time. Such time delays are virtually eliminated in the method according to the invention. The partial search areas do not overlap (minimal overlap of the partial search areas, for example, a common boundary of the partial search areas, may be present in some examples).The method divides the search area into the best possible sub-areas, minimizing the overall search time required for cooperatively searching the area to achieve a desired detection probability. In other words, the time needed to search an area is minimized while ensuring a minimum detection probability for targets or objects of a predetermined size at a predetermined distance. This results in time savings when searching a three-dimensional volume, which can be specified by the pilot. This leads to a more effective and, above all, significantly faster search, especially when the search area is arbitrarily defined.

[0031] It should be noted that the features of the exemplary embodiments of the method also apply to embodiments of the missile and missile formation, and vice versa. Furthermore, features not explicitly mentioned can also be freely combined.

[0032] These and other aspects of the invention will become apparent with reference to the following explanations. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The following section describes exemplary embodiments of the invention in more detail with reference to the accompanying drawings. These show: Fig. 1 shows a sketch of two missiles and a search area; Fig. 2 shows an example of a search area to be searched in a coordinate system; Fig. 3 shows an example of a search area to be searched in a coordinate system; Fig. 4 shows the division of the search area S1 from Figure 2into two sub-search areas TS1, TS2; Fig. 5 shows the division of search area S2 from Figures 3 into two sub-search areas TS1, TS2; Fig. 6 shows a prior art example. DETAILED DESCRIPTION OF EMBODIMENTS

[0034] Figure 1 The diagram shows two missiles, AC1 and AC2, and a search area, S. Both missiles, AC1 and AC2, are in the air. Each missile, AC1 and AC2, is equipped with a radar, R. The search area, S, is a three-dimensional region located in the vicinity of missiles AC1 and AC2. In some embodiments, missiles AC1 and AC2 fly in a formation.

[0035] The search area S is divided into two sub-search areas TS1 and TS2, which are searched by the radar R of the respective missiles AC1 and AC2. Sub-search areas TS1 and TS2 do not overlap. The search of sub-search areas TS1 and TS2 is performed cooperatively. As described in the following figures, sub-search areas TS1 and TS2 encompass the entire search area S.

[0036] Figures 2 and 3 Each figure shows a search area S1 or S2. The missiles AC1 and AC2 are flying at an altitude of 10 km and are 500 m apart on the Y-axis shown. For clarity, missiles AC1 and AC2 are barely distinguishable. The numerical data is for illustrative purposes only. The search area or sub-search areas are specified below using the azimuth angle θ (horizontal angle) and elevation angle φ (vertical angle), and the half-width θ-S1, θ-S2 for the azimuth angle and φ-S1, φ-S2 for the elevation angle.

[0037] In Figure 2The search area S1 is to be searched by the respective radar R of missiles AC1 and AC2. This area is centered at an azimuth angle θ = 0° and an elevation angle φ = 0°, i.e., directly in front of missiles AC1 and AC2, with an angular width θ-S1 of -25° to 25° for the azimuth angle and φ-S1 of -25° to 25° for the elevation angle. Such a search area is standard practice to avoid collisions with other missiles.

[0038] In Figure 3The search area S2 is to be searched by the respective radar R of the missiles AC1 and AC2. This area is centered at an azimuth angle θ = 30° and an elevation angle φ = 20°, with an angular width θ-S1 of 5° to 55° for the azimuth angle and φ-S1 of -5° to 45° for the elevation angle. Such a search area represents a situation in which the pilots have been informed that potentially threatening targets or objects are approaching. In the case of unmanned aerial vehicles (UAVs), a corresponding device or system on the UAV receives this information. In other embodiments, it is possible for a ground station to receive the information.

[0039] In both Figures 2 and 3The search area S1, S2 is to be searched as quickly as possible, given a specific radar cross-section σ and range, and a predetermined detection probability PD. According to the procedure, the search area S1 or S2 is divided into two sub-search areas, which are cooperatively searched by the respective radars R of the two missiles AC1, AC2. The sub-search areas do not overlap.

[0040] The goal is to find a division of the search area S1, S2 such that the total search time for searching the entire area is minimized. A detection probability PD must be met. In some embodiments, a minimum detection probability for detecting a target or object of a given size and distance is guaranteed.

[0041] The procedure for dividing the search area S1 or S2 is performed for various combinations of two sub-search areas TS1 and TS2, and the total search time for scanning the search area S1 or S2 is determined. To obtain the optimal division of the search area S1 or S2, the azimuth angle range or the elevation angle range is varied in this example. Each missile AC1 or AC2 searches the entire elevation range but only a portion of the azimuth range, or the entire azimuth range but only a portion of the elevation range. Other combinations of divisions can be used in different examples.

[0042] For each combination, the radar illumination time per radar beam is determined. Then, all radar illumination times per missile AC1, AC2 are summed. The total search time for a search area S1, S2 is calculated as the maximum of the search times for the corresponding sub-search areas TS1, TS2.

[0043] The combination of the two search areas TS1 and TS2 with the lowest total search time is used for the subsequent search of search area S1 or S2. In this example, the determined geometric division according to a horizontal angle, vertical angle, and distance, the detection probability PD for an object or target, as well as the minimal total search time, lead to a fast search of search area S1 or S2 and thus to rapid situational awareness. For example, an impending collision risk can be avoided.

[0044] Figures 4 and 5 show the division of the search area S1, S2 from the Figures 2, 3 into two sub-search areas TS1, TS2. Each sub-search area TS1, TS2 is assigned to one of the missiles AC1, AC2 and is searched by the radar R of the respective missile AC1, AC2.

[0045] In Figure 4A symmetrical division into sub-search areas TS1 and TS2 can be seen. Such a division is intuitive and simple. The division ratio with respect to elevation is 25° / 25° for sub-search areas TS1 and TS2. Search area S1 is as shown in Figure 2 described.

[0046] In Figure 5 A division into sub-search areas TS1 and TS2 can be seen. The elevation ratio is 27.8° / 22.2° for sub-search areas TS1 and TS2. Search area S2 is as shown in Figure 3 described.

[0047] The figures show when a search area is symmetrical around the antenna normal of the radar sensor (cf. Fig. 2If the search area is symmetrical, a symmetrical division of the sub-search areas TS1 and TS2 results in a minimal overall search time. However, if the search area is not symmetrical, a symmetrical division leads to a longer overall search time, so significant time delays when searching the search area are to be expected.

[0048] The time required to run the process to find the best division for the respective search area is significantly faster than searching the search area itself, so this hardly affects the overall search time.

[0049] In another example, the division of the search area S1, S2 into the two sub-search areas TS1, TS2 changes with the movement or trajectory of the missiles. In some examples, the division into the sub-search areas TS1, TS2 is continuously adjusted.

[0050] In some embodiments, the method is carried out in a corresponding device, for example, of missile AC1. For this, only the position of the other missile AC2 is required (see also...). Figure 1 This is necessary. This then assigns the search area TS2 to be searched to the other missile AC2. For example, only the following values ​​are transmitted to the other missile AC2: azimuth and elevation centerlines and the half-width of the search area TS2 assigned to the other missile AC2. This creates a central control mechanism for the process.

[0051] However, it is also possible for missiles AC1 and AC2 to independently define the search area TS1 and TS2, respectively, which is to be searched by their radar R. This independent assignment of the search area TS1 and TS2 by each missile creates a decentralized control system.

[0052] The described missiles AC1 and AC2 are equipped accordingly to carry out the procedure and to search the search area. For example, such a missile also has a processing unit for carrying out the procedure.

[0053] Figure 6 This shows the search of an area S in an airspace according to the state of the art. The search is performed non-cooperatively. In particular, the areas A and B, which are searched by the respective missiles AC1 and AC2, are divided such that these areas A and B largely overlap, as shown in Figure 6 This is shown. This increases the overall search time and leads to delays in situational awareness.

[0054] The embodiments described above can be combined in various ways. In particular, aspects of the method can also be used for embodiments of the devices as well as for the use of the devices, and vice versa. The illustrations in the figures are schematic and not to scale. If the same reference numerals are used in different figures in the following figure description, they denote identical or similar elements. However, identical or similar elements can also be designated by different reference numerals.

[0055] It should also be noted that "comprehensive" does not exclude any other elements or steps, and "a" or "an" does not exclude a plurality. Furthermore, it should be noted that features or steps described with reference to one of the above embodiments may also be used in combination with other features or steps of other embodiments described above. Reference numerals in the claims are not to be considered as limitations.

Claims

1. Method for searching a search area (S), wherein at least one radar (R) is arranged in each of at least two missiles (AC1, AC2), comprising: a) splitting the search area (S) into at least two search subareas (TS1, TS2), b) searching the at least two search subareas (TS1, TS2) by means of the respective radar (R) of the at least two missiles (AC1, AC2), wherein the at least two missiles (AC1, AC2) carry out the searching cooperatively, wherein the search subareas (TS1, TS2) are chosen such that a total search time is minimal; wherein the splitting of the search area (S) into search subareas (TS1, TS2) is continually adapted according to the movement and / or the trajectory of the at least two missiles (AC1, AC2); characterized in that the splitting of the search area (S) is performed for different combinations of in each case two search subareas (TS1, TS2), and the total search time for searching the search area (S) is ascertained; and in that the combination of the two search subareas (TS1, TS2) having the shortest total search time is used for the subsequent searching of the search area (S).

2. Method according to Claim 1, wherein the total search time is the maximum from the search times for the applicable search subareas (TS1, TS2).

3. Method according to either of the preceding claims, wherein the probability of detection (PD) of an object in the search area (S) is prescribable or predefined.

4. Method according to one of the preceding claims, wherein the search subareas (TS1, TS2) have substantially no overlap.

5. Method according to one of the preceding claims, wherein the search area (S) is prescribable or alterable.

6. Method according to one of the preceding claims, wherein a minimal probability of detection of an object of prescribed size at a prescribed distance is ensured.

7. Method according to one of the preceding claims, wherein a search subarea (TS1, TS2) is determined based on a horizontal angle, a vertical angle and associated angle widths, or based on three-dimensional coordinates.

8. Method according to one of the preceding claims, wherein one of the at least two missiles (AC1, AC2) assigns the search subarea (TS1, TS2) to be searched to the at least one other missile (AC1, AC2).

9. Method according to one of the preceding claims, wherein the at least two missiles (AC1, AC2) each independently of one another stipulate the search subarea (TS1, TS2) that is supposed to be searched by the radar (R) of the missile (AC1, AC2).

10. Missile (AC1, AC2) for a missile formation according to Claim 11, comprising at least one radar (R) and a process unit, wherein the process unit is configured to perform a method according to one of Claims 1-9.

11. Missile formation comprising at least two missiles (AC1, AC2) according to Claim 10, wherein the missile formation is configured to cover a search area (S) in an airspace.