An unmanned aerial vehicle cluster infrared guidance automatic landing method and system

Abstract

The present application relates to the technical field of unmanned aerial vehicle cluster control and autonomous landing, in particular to an unmanned aerial vehicle cluster infrared guidance automatic landing method and system, the present application arranges infrared guidance emitting devices at four corners of a ground rectangular landing area, each device divides the airspace into multiple sub-airspaces and emits infrared signals containing device codes, landing permission codes and check codes in turn through time division multiplexing. The unmanned aerial vehicle decodes the four-corner signals to obtain its three-dimensional coordinates and height information in the airspace, realizing accurate positioning and guidance without satellite signals. The system controls the landing sequence in cooperation, guides the unmanned aerial vehicles to land in batches in the order of odd-numbered rows of odd numbers, odd-numbered rows of even numbers, even-numbered rows of odd numbers and even-numbered rows of even numbers, effectively avoiding collision risks. The present application has the advantages of strong anti-interference ability, high positioning accuracy, good cooperativeness and suitability for complex electromagnetic environments.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of unmanned aerial vehicle cluster control and autonomous landing, and particularly relates to an unmanned aerial vehicle cluster infrared guidance automatic landing method and system. BACKGROUND

[0002] With the wide application of unmanned aerial vehicle cluster in military, logistics, surveying and mapping and other fields, cluster cooperative landing has become one of the key technologies. At present, the unmanned aerial vehicle cluster landing relies on GPS, Beidou or RTK and other high-precision satellite positioning systems, but in the environment of strong electromagnetic interference, urban canyons or obvious multipath effect, satellite signals are easily disturbed or blocked, resulting in positioning failure, landing confusion and even collision.

[0003] In the prior art, some schemes use ground beacons + airborne receivers for relative positioning, but there are problems such as signal conflict, low airspace resolution, and inability to support large-scale clusters. Another scheme introduces visual recognition, but it is only applicable to low-altitude stage and lacks global positioning capability in medium and high altitudes, so it needs to be improved SUMMARY

[0004] Therefore, the present application aims to provide an unmanned aerial vehicle cluster infrared guidance automatic landing method and system to solve the problem that the existing unmanned aerial vehicle cluster cannot realize safe, orderly and high-precision landing in the condition of strong electromagnetic interference, complex environment or satellite signal failure. The present application divides the airspace by coding by using infrared signals by laying multiple infrared guidance transmitting devices on the ground, and realizes three-dimensional accurate positioning and cooperative guidance landing of unmanned aerial vehicles in the absence of satellite signals by combining time division multiplexing transmission and four-corner intersection positioning algorithm.

[0005] In order to achieve the above purpose, the present application provides an unmanned aerial vehicle cluster infrared guidance automatic landing method, which comprises the following steps:

[0006] S1: arranging unmanned aerial vehicle boxes in a grid in a rectangular landing area, each box corresponding to a unit cell and numbered, and laying infrared guidance transmitting devices at the four corners of the rectangular landing area, each infrared guidance transmitting device comprising multiple infrared transmitting units, all infrared transmitting units transmitting infrared signals in a time division multiplexing manner, for dividing the covered airspace into multiple sub-airspaces with unique codes;

[0007] S2: after the unmanned aerial vehicle cluster returns to the upper space of the rectangular landing area, each unmanned aerial vehicle receives the infrared signals transmitted from the four infrared guidance transmitting devices by the airborne infrared receiver, and decodes to obtain the corresponding sub-airspace code information;

[0008] S3: based on the decoded sub-airspace code information from the four directions, combined with the known spatial coordinates of each infrared guidance transmitting device, the three-dimensional coordinates of each unmanned aerial vehicle in the airspace are calculated by the four-corner intersection positioning algorithm.

[0009] S4: According to the preset landing order strategy, the landing permission signal is sent to the UAV cluster in batches, and the UAVs are controlled to land in batches at different times;

[0010] S5: When the UAVs descend to a preset height close to the ground, the UAVs are guided by the on-board visual sensor, and are recognized and landed in the specified ground machine box;

[0011] S6: After the UAVs land, a landing homing signal is sent, and after all the current batch is confirmed, the sending of the landing permission signal of the next batch is triggered, until all the UAVs land.

[0012] Preferably, in step S1, the plurality of infrared emission units in each infrared guidance emission device are arranged in a honeycomb shape, and each infrared emission unit corresponds to a fixed radiation direction, which defines a sub-space with a unique code together with the infrared guidance emission device.

[0013] Preferably, in step S1, the infrared signal is emitted at a frequency of 50Hz, and each emission period is 20ms, wherein the four infrared guidance emission devices occupy a 5ms time window in turn, and the infrared emission units inside them are activated in a fixed order in their respective windows, ensuring that only one infrared emission unit is in the emission state at any time.

[0014] Preferably, in step S2, the infrared signal contains a guidance device code, a landing permission code and a check code, each UAV receives the infrared signal emitted from the four infrared guidance emission devices through the on-board infrared receiver, and decodes the guidance device code in each signal, and determines the activated infrared emission unit identifier according to the signal receiving timestamp, and combines the guidance device code with the infrared emission unit identifier as the sub-space code information from the direction.

[0015] Preferably, in step S3, the calculation steps of the four-edge intersection positioning algorithm are as follows:

[0016] S3.1: Map each sub-space code information to the azimuth and pitch angle from the corresponding infrared guidance emission device to the UAV;

[0017] S3.2: Construct a direction unit vector according to the known coordinates and angles of the four infrared guidance emission devices;

[0018] S3.3: Establish a geometric relationship equation containing an unknown distance, and form a linear equation set after eliminating the distance parameter;

[0019] S3.4: Solve the linear equation set by using the least square method to obtain the optimal estimate of the three-dimensional coordinates of the UAV.

[0020] Preferably, in step S3.1, the following steps are specifically included:

[0021] S3.11: Coordinate system definition

[0022] Let the global coordinate system be , where the coordinates of the four infrared guide emitting devices are respectively:

[0023] ;

[0024] The coordinates to be solved of the UAV are ; ;

[0025] S3.12: Mapping of encoding to direction angle

[0026] The UAV decodes the infrared code from the infrared guide emitting device ( ) to obtain the azimuth angle and the pitch angle through a preset mapping function ; ;

[0027] ;

[0028] In step S3.2, the unit direction vector pointing to the UAV from the infrared guide emitting device is:

[0029] ;

[0030] In step S3.3, according to the spatial geometric relationship, we have:

[0031] ;

[0032] where is the unknown distance from the infrared guide emitting device to the UAV;

[0033] From the above formula, the proportional relationship can be obtained, and after eliminating , two linear equations are obtained:

[0034] ;

[0035] In step S3.4, four infrared guide emitting devices are obtained linear equations, which are arranged in matrix form as follows:

[0036] ;

[0037] where:

[0038] ;

[0039] is a coefficient matrix, is a constant vector, specifically:

[0040] ;

[0041] Solving the overdetermined equation group by the least square method, the optimal estimation of the three-dimensional coordinates of the UAV is obtained:

[0042] = .

[0043] Preferably, the landing permission signal in step S4 is a landing permission code, and the specific steps are as follows: generating a landing permission code containing the number of the UAVs authorized to land in the current batch according to a preset landing order strategy, and controlling the infrared guidance emitting device to embed the landing permission code in the infrared signal and broadcast it, each UAV judging whether its own number is contained in the received landing permission code, if yes, starting the landing program;

[0044] The landing order strategy is to execute in four batches according to the row and column numbers of the target machine box in the grid:

[0045] The first batch: UAVs with odd row numbers and odd column numbers;

[0046] The second batch: UAVs with odd row numbers and even column numbers;

[0047] The third batch: UAVs with even row numbers and odd column numbers;

[0048] The fourth batch: UAVs with even row numbers and even column numbers.

[0049] Preferably, in step S4, if a UAV does not receive the landing permission code in the current batch, the UAV remains hovering or executes an avoidance flight strategy, and continuously listens to the landing permission code of the subsequent batch.

[0050] Preferably, in step S5, the preset height is 2 meters, when the UAV descends below this height, the onboard visual sensor is automatically enabled to identify the two-dimensional code or ArUco marker set on the ground machine box, and the final landing is completed based on the visual feedback.

[0051] A UAV cluster infrared guidance automatic landing system, comprising:

[0052] Four infrared guidance emitting devices are arranged at the four corners of the rectangular landing area, and each infrared guidance emitting device contains a plurality of infrared emitting units;​​

[0053] a time synchronization module for realizing time division multiplexing emission control of the four infrared guidance emission devices and the infrared emission units inside them;

[0054] a ground control unit, which is communicatively connected with the infrared guidance emission devices, for generating a landing permission code and controlling the infrared signal content;

[0055] a UAV cluster, each UAV being equipped with an infrared receiver, a visual sensor and a flight control processor;

[0056] The infrared receiver has a timestamp recording function for inferring the activated infrared emission unit identifier according to the signal receiving time, and the flight control processor is configured to perform three-dimensional positioning based on the sub-airspace encoding information formed by the combination of the guidance device code and the infrared emission unit identifier inferred from the timestamp, and to control the landing behavior according to the landing permission code

[0057] The beneficial effects of the present application are as follows:

[0058] I. By arranging infrared guidance emission devices at the four corners of the landing area and dividing the airspace into multiple sub-airspaces, the UAV can calculate its three-dimensional coordinates only by receiving infrared signals, and the infrared light signal as a guidance medium is not affected by radio electromagnetic interference, thus fundamentally solving the key problem that the UAV cluster cannot reliably land in a complex electromagnetic environment, GPS / RTK signal denial or blocked scene, and realizing truly satellite signal-independent autonomous landing.

[0059] II. By using a strictly synchronized time division multiplexing architecture, only one infrared emission unit (LED) is in an activated state at any time, and the activation sequence and timing are completely fixed. Therefore, the unique identifier (unit ID) of the infrared emission unit does not need to be explicitly encoded in the infrared signal frame, but is directly inferred by the UAV according to the signal receiving timestamp in the preset timing table, which greatly simplifies the infrared signal frame structure, avoids spatial confusion caused by multiple LEDs emitting light at the same time, and also eliminates signal crosstalk, greatly improving the anti-interference ability and decoding accuracy of the positioning system.

[0060] III. In the middle and high altitudes, global navigation is performed by relying on infrared airspace encoding, and in the low altitude (<2 meters), the system automatically switches to visual mode to identify the ArUco or two-dimensional code markers on the machine box, taking into account the coverage range and end accuracy. This fusion method takes into account the guidance range, anti-interference ability and ultimate landing accuracy, ensuring that the UAV can accurately land in the specified small-sized machine box. BRIEF DESCRIPTION OF DRAWINGS

[0061] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only illustrate the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained based on these drawings without any creative effort.

[0062] Figure 1 The flowchart of the present application. DETAILED DESCRIPTION

[0063] In order to make the objectives, technical solutions and advantages of the present application clearer, the following will further describe the present application in detail with specific embodiments and with reference to the drawings.

[0064] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should be understood as the common meanings understood by those skilled in the art to which the present application belongs. The terms "first", "second" and similar terms used in the present application do not represent any order, number or importance, but are only used to distinguish different components. The terms "include" or "contain" and similar terms mean that the components or objects before the terms cover the components or objects listed after the terms and their equivalents, and do not exclude other components or objects. The terms "connect" or "connected" and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms "upper", "lower", "left", "right" and the like are only used to represent relative positional relationships, and when the absolute positions of the described objects are changed, the relative positional relationships may also be changed accordingly.

[0065] As shown in Figure 1 An unmanned aerial vehicle cluster infrared guidance automatic landing method, comprising the following steps:

[0066] S1: arranging unmanned aerial vehicle boxes in a grid in a rectangular landing area, each box corresponding to a unit cell and numbered, and arranging infrared guidance emission devices at the four corners of the rectangular landing area, each infrared guidance emission device comprising a plurality of infrared emission units, all the infrared emission units emitting infrared signals in turn in a time division multiplexing manner, for dividing the coverage airspace into a plurality of sub-airspaces with unique codes;

[0067] The plurality of infrared emission units in each infrared guidance emission device are arranged in a honeycomb shape, and each infrared emission unit corresponds to a fixed radiation direction, each infrared emission unit having a fixed installation azimuth angle and pitch angle, and the radiation direction covering a preset solid angle region, which together with the infrared guidance emission device defines a sub-airspace with a unique code.

[0068] The uniquely coded sub-space refers to a three-dimensional space region covered by a specific infrared emission unit in an infrared guidance emission device, with fixed azimuth and elevation angles.

[0069] The infrared signals are emitted at a frequency of 50Hz, with each emission cycle being 20ms, wherein the four infrared guidance emission devices take turns to occupy a 5ms time window, and in each window, the infrared emission units inside are activated in a fixed order, ensuring that only one infrared emission unit is in the emission state at any time.

[0070] S2: After the UAV cluster returns to the airspace above the rectangular landing area, each UAV receives the infrared signals from the four infrared guidance emission devices through the onboard infrared receiver; the infrared signals contain the guidance device code (identifying the infrared guidance emission device number), the landing permission code (containing the list of UAV numbers allowed to land), and the check code (used to check the signal integrity), and the guidance device code in each signal is decoded (identifying the signal source vertex), and the corresponding infrared emission unit identifier is determined according to the signal reception timestamp (because the time division multiplexing sequence is fixed, the time position can be mapped to the unit number); the guidance device code and the infrared emission unit identifier are combined as the sub-space coding information in that direction.

[0071] The sub-space coding information refers to a combination of numbers or symbols used to uniquely identify a sub-space, which is composed of the device identifier of the infrared guidance emission device and the unique number of the infrared emission unit.

[0072] S3: Based on the decoded sub-space coding information from the four directions, combined with the known spatial coordinates of each infrared guidance emission device, the three-dimensional coordinates of each UAV in the airspace are calculated by the four-corner intersection positioning algorithm;

[0073] The calculation steps of the four-corner intersection positioning algorithm are as follows:

[0074] S3.1: Map each sub-space coding information to the azimuth and elevation angles from the corresponding infrared guidance emission device to the UAV;

[0075] In step S3.1, the following steps are included:

[0076] S3.11: Coordinate system definition

[0077] Let the global coordinate system be , and the coordinates of the four infrared guidance emission devices are

[0078] ;

[0079] The to-be-solved coordinates of the UAV are ;

[0080] S3.12: Mapping of the encoded direction angle

[0081] The UAV decodes the infrared code from the infrared guidance launch device ) into a direction angle , which is converted into an azimuth angle and a pitch angle by a preset mapping function ;

[0082] ;

[0083] S3.2: Constructing a direction unit vector according to the known coordinates and angles of the four infrared guidance launch devices;

[0084] In step S3.2, the unit direction vector pointing to the UAV from the infrared guidance launch device is:

[0085] ;

[0086] S3.3: Establishing a geometric relationship equation containing an unknown distance and forming a linear equation set after eliminating the distance parameter;

[0087] In step S3.3, according to the spatial geometric relationship, we have:

[0088] ;

[0089] where is the unknown distance from the infrared guidance launch device to the UAV;

[0090] From the above formula, a proportional relationship can be obtained, and after eliminating , two linear equations are obtained:

[0091] ;

[0092] S3.4: Solving the linear equation set by using the least squares method to obtain the optimal estimation of the three-dimensional coordinates of the UAV;

[0093] In step S3.4, a total of linear equations are obtained for the four infrared guidance launch devices , which are arranged in matrix form as follows:

[0094] ;

[0095] where:

[0096] ;

[0097] ​ is a coefficient matrix, is a constant vector, specifically:

[0098]

[0099] Solving the overdetermined equation group by least square method, the optimal estimation of the three-dimensional coordinates of the UAV is obtained:

[0100]

[0101] S4: According to the preset landing order strategy, the landing permission signal is sent to the UAV cluster in batches, and the UAVs are controlled to land in batches at different times;

[0102] In step S4, the landing permission signal is a landing permission code, and the specific steps are as follows: according to the preset landing order strategy, a landing permission code containing the number of the UAVs authorized to land in the current batch is generated, and the infrared guidance emission device is controlled to embed the landing permission code in the infrared signal and broadcast it. Each UAV judges whether its own number is contained in the received landing permission code, if yes, the landing program is started;

[0103] The landing permission code is a data field, which contains a list of unique identifiers of the UAVs authorized to land in the current batch, and the list is encoded in the infrared signal frame in a predefined order.

[0104] The landing order strategy is to execute in four batches according to the row and column numbers of the target machine box in the grid:

[0105] The first batch: UAVs with odd row numbers and odd column numbers;

[0106] The second batch: UAVs with odd row numbers and even column numbers;

[0107] The third batch: UAVs with even row numbers and odd column numbers;

[0108] The fourth batch: UAVs with even row numbers and even column numbers.

[0109] In step S4, if a UAV does not receive the landing permission code containing the current batch, the UAV remains hovering or executes the avoidance flight strategy, and continuously listens to the landing permission code of the subsequent batch; In addition, the system can dynamically adjust the landing order, skip the abnormal UAV, and ensure the overall process.

[0110] S5: When the UAV descends to a preset height close to the ground, it switches to guidance by the onboard vision sensor, identifies and lands in the specified ground machine box;

[0111] ​​​​​In step S5, the preset height is 2 meters, when the UAV is lowered below this height, the on-board visual sensor is automatically enabled, the two-dimensional code or ArUco marker arranged on the ground machine box is identified, and the final landing is completed based on the visual feedback.

[0112] S6: After the UAV landing is completed, a landing homing signal is sent, after all the current batch is confirmed, the sending of the landing permission signal of the next batch is triggered, until all the UAVs land.

[0113] After the UAV successfully lands, a "landing homing" signal is sent to the ground system through short-range wireless communication (such as Bluetooth, NFC, etc.) or wired way. After the ground system confirms that all UAVs in this batch have landed, it updates the status and sends the landing permission code of the next batch until all UAVs land.

[0114] An unmanned aerial vehicle cluster infrared guidance automatic landing system, comprising:

[0115] Four infrared guidance emitting devices are arranged at the four corners of the rectangular landing area, each infrared guidance emitting device contains a plurality of infrared emitting units;

[0116] A time synchronization module is used to realize time division multiplexing emission control of the four infrared guidance emitting devices and the infrared emitting units inside them;

[0117] A ground control unit is communicatively connected to the infrared guidance emitting devices for generating landing permission codes and controlling infrared signal content;

[0118] An unmanned aerial vehicle cluster, each unmanned aerial vehicle is equipped with an infrared receiver, a visual sensor (such as a camera) and a flight control processor;

[0119] The infrared receiver has a timestamp recording function for inferring the activated infrared emitting unit identifier according to the signal receiving time, and the flight control processor is configured to perform three-dimensional positioning based on the sub-airspace encoding information formed by the combination of the guidance device code and the infrared emitting unit identifier inferred from the timestamp, and control the landing behavior according to the landing permission code.

[0120] Taking a 50m×50m site UAV cluster landing as an example:

[0121] 1. System arrangement

[0122] A flat 50m×50m site is selected as the landing area, divided into a 2m×2m grid, a total of 625 cells, each cell center placed a UAV machine box, numbered from (1, 1) to (25, 25).

[0123] Four infrared guidance transmitters are set up at the corners of the field (coordinates: A corner (0, 0), B corner (50, 0), C corner (0, 50), D corner (50, 50)), with an installation height of 1 m, ensuring that the infrared signal covers the entire airspace.

[0124] Each infrared guidance transmitter is internally integrated with 9 x 9 = 81 high-power infrared LED units arranged in a honeycomb pattern, with a wavelength of 940 nm and an emission frequency of 37 kHz. Each unit corresponds to a unique 6-bit binary code, which can represent 64 different states, fully meeting the coding needs of 81 units.

[0125] 2. Time synchronization and signal transmission

[0126] The four infrared guidance transmitters communicate through wired connection to achieve time synchronization.

[0127] The system transmits infrared signals at a frequency of 50 Hz, with a 20 ms cycle for each. The four infrared guidance transmitters take turns transmitting, with each occupying a 5 ms window. Within the transmission window of each infrared guidance transmitter, its 81 emission units take turns in sequence, with each unit emitting for about 61.7 μs.

[0128] 0-5 ms: The infrared guidance transmitter at the A corner works, with its 81 LEDs activated in sequence, each unit lasting about 61.7 μs;

[0129] 5-10 ms: The infrared guidance transmitter at the B corner works;

[0130] 10-15 ms: The infrared guidance transmitter at the C corner works;

[0131] 15-20 ms: The infrared guidance transmitter at the D corner works.

[0132] The signal frame structure is: 2 bytes of guidance device code (to distinguish the four corners) + 4 bytes of landing permission code (can accommodate multiple UAV numbers) + 2 bytes of CRC check code.

[0133] 3. UAV configuration

[0134] Each UAV is equipped with a wide-angle infrared receiver at the bottom, with a viewing angle of more than 120°, ensuring that it can receive signals from multiple directions simultaneously.

[0135] The on-board processor integrates decoding and positioning algorithms to calculate its position in real time.

[0136] The UAV is equipped with a camera on the belly for low-altitude visual guidance.

[0137] When the UAV receives a signal, it performs the following steps:

[0138] Decode the obtained guiding device code (e.g. A);

[0139] Calculate the infrared emission unit identification according to the received timestamp, e.g. according to the received time t = 3.2 ms, it is judged to be in the A angle window (0-5 ms), and the offset is 3.2 ms → corresponding to the 52nd LED (3.2 ms / 61.7 μs ≈ 52);

[0140] Combine the obtained sub-space domain coding information (e.g. A, 52) to query the locally pre-stored direction mapping table to obtain the direction angle;

[0141] Four directions intersect, and the three-dimensional coordinates (x, y, z) are obtained by least squares method.

[0142] 4. Landing process example

[0143] Suppose there are 30 drones to be landed, and the box numbers have been assigned in advance.

[0144] After the drone cluster returns, it hovers at an altitude of 30 meters.

[0145] The ground control unit specifies a four-batch landing strategy according to the box grid (25 rows × 25 columns):

[0146] First batch: odd rows and odd columns (e.g. (1, 1), (1, 3), (3, 1), etc.)

[0147] Second batch: odd rows and even columns (e.g. (1, 2), (1, 4), etc.);

[0148] Third batch: even rows and odd columns;

[0149] Fourth batch: even rows and even columns;

[0150] First, send the first batch of landing permission code, containing the numbers of all odd rows and odd numbers and drones to be landed (e.g. (1, 1), (1, 3), (3, 1), etc.).

[0151] Before each batch starts, the ground control unit generates a landing permission code containing the numbers of the drones in that batch, and broadcasts it through infrared signals. Only when the drone's own ID is in the permission code, will it start landing.

[0152] When the altitude is reduced to 2 meters, the drone switches to visual guidance, the camera recognizes the two-dimensional code on the box, and performs the final stage of precise hovering and landing.

[0153] After landing, the drone sends a landing homing signal to the ground control unit through a wireless link (e.g. LoRa). The ground control unit counts and confirms the number, and after all the current batch is homed, the second batch of permission code (odd rows and even numbers) is sent, and so on, until all the drones are landed.

[0154] 5. Abnormality handling and dynamic scheduling

[0155] If a UAV does not receive a valid infrared signal for 3 consecutive periods, or its ID is not included in the current permission code, it executes a hover-wait strategy and continues to listen for subsequent signals.

[0156] In addition, the ground control unit supports dynamic priority adjustment: for example, when the power of a UAV is less than 15%, it can be temporarily added to the next emergency batch to achieve priority landing.

[0157] It should be understood by those of ordinary skill in the art that the above discussion of any of the embodiments is merely exemplary and is not intended to suggest that the scope of the present application is limited to these examples; under the idea of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the present application as described above, which are not provided in details for the sake of brevity.

[0158] Embodiments of the present application are intended to cover all such alternatives, modifications, and variations as fall within the broad scope of the appended claims. Accordingly, any one of the steps of the application can be performed in any order, and in some embodiments, simultaneously. Any recitation of numerical range is intended to include all values subsumed therein. Any reference to the method of the application is intended to include the process of the application. Any reference to the composition of the application is intended to include the composition of the application. Any reference to the use of the application is intended to include the use of the application. Any reference to the kit of the application is intended to include the kit of the application. Any reference to the article of manufacture of the application is intended to include the article of manufacture of the application. Any reference to the method of the application is intended to include the process of the application. Any reference to the composition of the application is intended to include the composition of the application. Any reference to the use of the application is intended to include the use of the application. Any reference to the kit of the application is intended to include the kit of the application. Any reference to the article of manufacture of the application is intended to include the article of manufacture of the application. Any reference to the method of the application is intended to include the process of the application. Any reference to the composition of the application is intended to include the composition of the application. Any reference to the use of the application is intended to include the use of the application. Any reference to the kit of the application is intended to include the kit of the application. Any reference to the article of manufacture of the application is intended to include the article of manufacture of the application. Any reference to the method of the application is intended to include the process of the application. Any reference to the composition of the application is intended to include the composition of the application. Any reference to the use of the application is intended to include the use of the application. Any reference to the kit of the application is intended to include the kit of the application. Any reference to the

Claims

1. A method for infrared-guided automatic landing of a swarm of unmanned aerial vehicles (UAVs), characterized in that, Includes the following steps: S1: Infrared guiding transmitters are deployed at the four corners of the rectangular landing area. Each infrared guiding transmitter includes multiple infrared transmitting units. The multiple infrared transmitting units in each infrared guiding transmitter are arranged in a honeycomb pattern, and each infrared transmitting unit corresponds to a fixed radiation direction. Together with its respective infrared guiding transmitter, it defines a sub-spatial domain with a unique code. All infrared transmitting units take turns transmitting infrared signals in a time-division multiplexing manner to divide the covered airspace into multiple sub-spatial domains with unique codes. S2: After the drone swarm returns to the rectangular landing area, each drone receives infrared signals emitted from four infrared guidance transmitters via its onboard infrared receiver. The infrared signals contain guidance device codes, landing permission codes, and verification codes. Each drone receives the infrared signals emitted from the four infrared guidance transmitters via its onboard infrared receiver and decodes them to obtain the guidance device code in each signal. At the same time, it determines the active infrared transmitter unit identifier based on the signal reception timestamp and combines the guidance device code with the infrared transmitter unit identifier as sub-airspace coding information from that direction. S3: Based on the sub-airspace coding information obtained from the four directions through decoding, combined with the known spatial coordinates of the infrared guidance and transmitting devices at each location, the three-dimensional coordinates of each UAV in the airspace are calculated through the quadruple intersection positioning algorithm; S4: Based on the preset landing sorting strategy, send landing permission signals to the drone cluster in batches to control the drones to land in batches at staggered times; S5: When the drone descends to a preset altitude close to the ground, it switches to being guided by the onboard visual sensor to identify and land in the designated ground enclosure; S6: After the drone has landed, it sends a landing clearance signal. Once the current batch is confirmed, it triggers the sending of the landing clearance signal for the next batch, until all drones have landed.

2. The method for infrared-guided automatic landing of a drone swarm according to claim 1, characterized in that, In step S1, the infrared signal is emitted at a frequency of 50Hz, and each emission cycle is 20ms. The four infrared guiding emission devices occupy a 5ms time window in turn. Within their respective windows, the infrared emission units inside are activated in a fixed order to ensure that only one infrared emission unit is in the emission state at any given time.

3. The method for infrared-guided automatic landing of a drone swarm according to claim 1, characterized in that, In step S3, the calculation steps using the quad intersection positioning algorithm are as follows: S3.1: Map each sub-space domain encoding information to the azimuth and pitch angles from the corresponding infrared guidance transmitter to the UAV; S3.2: Construct a unit directional vector based on the known coordinates and angles of the four infrared guiding transmitters; S3.3: Establish geometric relationship equations that include unknown distances, and form a system of linear equations after eliminating the distance parameters; S3.4: Solve the linear equations using the least squares method to obtain the optimal estimate of the UAV's three-dimensional coordinates.

4. The method for infrared-guided automatic landing of a drone swarm according to claim 3, characterized in that, Step S3.1 specifically includes the following steps: S3.11: Coordinate System Definition Establish a global coordinate system In the diagram, the coordinates of the four infrared guiding transmitters are as follows: ； drones The coordinates to be determined are ; S3.12: Mapping of encoding to direction angle The drone decodes the data from the infrared-guided transmitter. Infrared encoding Through a preset mapping function Convert to azimuth and pitch angle ; ； In step S3.2, the infrared-guided transmitter... Unit direction vector pointing to the drone for: ； In step S3.3, based on spatial geometric relationships, we have: ； in Infrared guided transmitter The unknown distance to the drone; The proportional relationship is obtained from the above formula, and then... Two linear equations were then obtained: ； In step S3.4, the four infrared guiding transmitters are... Total The linear equations, rearranged into matrix form: ； in: ； for The coefficient matrix, for A constant vector, specifically in the form of: ； The optimal estimate of the UAV's three-dimensional coordinates is obtained by solving the overdetermined system of equations using the least squares method. = 。 5. The method for infrared-guided automatic landing of a drone swarm according to claim 1, characterized in that, In step S4, the landing permission signal is a landing permission code. The specific steps are as follows: a landing permission code containing the number of the UAV authorized to land in the current batch is generated according to the preset landing sorting strategy, and the infrared guidance transmitter is controlled to embed the landing permission code into the infrared signal and broadcast it. Each UAV determines whether its own number is contained in the received landing permission code. If so, the landing procedure is started. The landing sorting strategy is to execute the landing in four batches based on the row and column numbers of the target chassis in the grid: The first batch: drones with odd row numbers and odd column numbers; The second batch: drones with odd row numbers and even column numbers; The third batch: drones with even row numbers and odd column numbers; The fourth batch: drones with even row numbers and even column numbers.

6. The method for infrared-guided automatic landing of a drone swarm according to claim 5, characterized in that, In step S4, if a drone does not receive a landing clearance code included in the current batch, the drone will remain hovering or execute an avoidance flight strategy and continue to listen for landing clearance codes in subsequent batches.

7. The method for infrared-guided automatic landing of a drone swarm according to claim 1, characterized in that, In step S5, the preset height is 2 meters. When the drone descends below this height, the onboard vision sensor is automatically activated to identify the QR code or ArUco mark set on the ground chassis, and the final landing is completed based on visual feedback.

8. An infrared-guided automatic landing system for a swarm of unmanned aerial vehicles (UAVs) to implement the method as described in any one of claims 1 to 7, characterized in that, include: Four infrared guidance and emission devices are deployed at the four corners of the rectangular landing area, and each infrared guidance and emission device contains multiple infrared emission units; The time synchronization module is used to realize time-division multiplexing transmission control of the four infrared guiding transmitters and their internal infrared transmitting units; The ground control unit is connected to the infrared guidance transmitter for generating landing clearance codes and controlling the content of infrared signals. A drone swarm, with each drone equipped with an infrared receiver, visual sensor, and flight control processor; The infrared receiver has a timestamp recording function, which is used to infer the activated infrared transmitting unit identifier based on the signal reception time. The flight control processor is configured to perform three-dimensional positioning based on the sub-airspace coding information formed by the combination of the guidance device code and the infrared transmitting unit identifier inferred by the timestamp, and to control the landing behavior according to the landing permission code.

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