Infrared-guided automatic landing method and system for unmanned aerial vehicle cluster

Abstract

The invention relates to the technical field of unmanned aerial vehicle cluster control and autonomous landing, in particular to an unmanned aerial vehicle cluster infrared guide automatic landing method and system.The infrared guide transmitting devices are arranged at the four corners of a ground rectangular landing area, and each device divides an airspace into a plurality of sub-airspaces; and infrared signals including the equipment code, the landing permission code and the check code are transmitted in turn in a time division multiplexing mode. And the unmanned aerial vehicle obtains three-dimensional coordinates and height information of the unmanned aerial vehicle in the airspace by receiving four-corner signals and decoding the four-corner signals, so that accurate positioning and guiding without satellite signals are realized. The system cooperatively controls the landing sequence, and guides the unmanned aerial vehicles to land in a staggered manner in batches according to the sequence of odd rows and odd numbers, odd rows and even numbers, even rows and odd numbers, and even rows and even numbers, so that the collision risk is effectively avoided. The method has the advantages of being high in anti-interference capability, high in positioning precision, good in collaboration and suitable for a complex electromagnetic environment.

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, step S3.1 specifically includes the following steps:

[0021] S3.11: Coordinate System Definition

[0022] Establish a global coordinate system In the diagram, the coordinates of the four infrared guiding transmitters are as follows:

[0023] ;

[0024] drones The coordinates to be determined are ;

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

[0026] The drone decodes the data from the infrared-guided transmitter. ( Infrared encoding Through a preset mapping function Convert to azimuth and pitch angle ;

[0027] ;

[0028] In step S3.2, the infrared-guided transmitter... Unit direction vector pointing to the drone for:

[0029] ;

[0030] In step S3.3, based on spatial geometric relationships, we have:

[0031] ;

[0032] in Infrared guided transmitter The unknown distance to the drone;

[0033] The proportional relationship can be obtained from the above formula, and then eliminating... Two linear equations were then obtained:

[0034] ;

[0035] In step S3.4, the four infrared guiding transmitters ( A total of The linear equations, rearranged into matrix form:

[0036] ;

[0037] in:

[0038] ;

[0039] for The coefficient matrix, for A constant vector, specifically in the form of:

[0040] ;

[0041] The optimal estimate of the UAV's three-dimensional coordinates is obtained by solving the overdetermined system of equations using the least squares method.

[0042] = .

[0043] Preferably, 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 included in the received landing permission code. If so, the landing procedure is started.

[0044] 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:

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

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

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

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

[0049] Preferably, 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.

[0050] Preferably, 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.

[0051] An infrared-guided automatic landing system for a swarm of unmanned aerial vehicles (UAVs) includes:

[0052] 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;

[0053] 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;

[0054] The ground control unit is connected to the infrared guidance transmitter for generating landing clearance codes and controlling the content of infrared signals.

[0055] A drone swarm, with each drone equipped with an infrared receiver, visual sensor, and flight control processor;

[0056] The infrared receiver has a timestamp recording function, 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 combining the guidance device code and the infrared transmitting unit identifier inferred from the timestamp, and to control the landing behavior according to the landing clearance code.

[0057] The beneficial effects of this invention are as follows:

[0058] I. By deploying infrared guidance transmitters at the four corners of the landing area and dividing the airspace into multiple sub-airspaces, the UAV can calculate its own three-dimensional coordinates simply by receiving infrared signals. Moreover, the infrared light signal, as the guidance medium, is not affected by radio electromagnetic interference. This fundamentally solves the key problem that UAV swarms cannot land reliably in complex electromagnetic environments or in scenarios where GPS / RTK signals are denied or blocked, thus achieving truly autonomous landing without satellite signal dependence.

[0059] Second, by utilizing a strictly synchronized time-division multiplexing architecture, only one infrared emitting unit (LED) is active at any given time, and its activation order and timing are completely fixed. Therefore, the unique identifier (unit ID) of the infrared emitting unit does not need to be explicitly encoded in the infrared signal frame, but is directly inferred by the UAV based on the position of the signal reception timestamp in the preset timing table. This mechanism greatly simplifies the infrared signal frame structure, avoids spatial confusion caused by multiple LEDs emitting light simultaneously, and eliminates signal crosstalk, greatly improving the anti-interference capability and decoding accuracy of the positioning system.

[0060] Third, at medium and high altitudes, global navigation relies on infrared airspace coding, while at low altitudes (<2 meters), it automatically switches to visual mode to identify ArUco or QR code markings on the chassis, balancing coverage and terminal accuracy. This fusion approach balances guidance range, anti-interference capability, and final landing accuracy, ensuring that the drone can accurately land in the designated small chassis. Attached Figure Description

[0061] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0062] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0064] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this invention should have the ordinary meaning understood by those skilled in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0065] like Figure 1 As shown, an infrared-guided automatic landing method for a drone swarm includes the following steps:

[0066] S1: Arrange UAV chassis in a grid within the rectangular landing area. Each chassis corresponds to a cell and is numbered. Infrared guidance and transmission devices are deployed at the four corners of the rectangular landing area. Each infrared guidance and transmission device includes multiple infrared transmission units. All infrared transmission units transmit infrared signals in turn in a time-division multiplexing manner to divide the covered airspace into multiple sub-airspaces with unique codes.

[0067] Multiple infrared emitting units in each infrared guiding and emitting device are arranged in a honeycomb pattern, and each infrared emitting unit corresponds to a fixed radiation direction. Each infrared emitting unit has a fixed installation azimuth angle and elevation angle, and its radiation direction covers a preset solid angle region. Together with its respective infrared guiding and emitting device, it defines a sub-space domain with a unique code.

[0068] A uniquely coded subspace refers to a three-dimensional spatial region with a fixed azimuth and elevation angle, radiated and covered by a specific infrared emitting unit in an infrared guiding and emitting device.

[0069] The infrared signal is emitted at a frequency of 50Hz, with each emission cycle lasting 20ms. The four infrared guiding and emitting devices each occupy a 5ms time window in turn. Within their respective windows, the infrared emitting units inside are activated in a fixed order to ensure that only one infrared emitting unit is in the emitting state at any given time.

[0070] S2: After the drone swarm returns to the rectangular landing area, each drone receives infrared signals from four infrared guidance transmitters via its onboard infrared receiver. The infrared signals contain a guidance device code (identifying the infrared guidance transmitter number), a landing permission code (containing a list of drone numbers that are allowed to land), and a check code (used to verify signal integrity). The guidance device code (identifying the vertex of the signal source) in each signal is decoded, and the corresponding infrared transmission unit identifier is determined based on the signal reception timestamp (because the time division multiplexing order is fixed, the time position can be mapped to the unit number). The guidance device code and the infrared transmission unit identifier are combined as the sub-airspace coding information for that direction.

[0071] Subspace coding information refers to a combination of numbers or symbols used to uniquely identify a subspace, which is composed of the equipment identifier of the infrared guiding transmitter and the unique number of the infrared transmitting unit.

[0072] 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;

[0073] The calculation steps using the quad intersection localization algorithm are as follows:

[0074] S3.1: Map each sub-space domain encoding information to the azimuth and pitch angles from the corresponding infrared guidance transmitter to the UAV;

[0075] Step S3.1 specifically includes the following steps:

[0076] S3.11: Coordinate System Definition

[0077] Establish a global coordinate system In the diagram, the coordinates of the four infrared guiding transmitters are as follows:

[0078] ;

[0079] drones The coordinates to be determined are ;

[0080] S3.12: Mapping of encoding to direction angle

[0081] The drone decodes the data from the infrared-guided transmitter. ( Infrared encoding Through a preset mapping function Convert to azimuth and pitch angle ;

[0082] ;

[0083] S3.2: Construct a unit vector of direction based on the known coordinates and angles of the four infrared guiding transmitters;

[0084] In step S3.2, the infrared-guided transmitter... Unit direction vector pointing to the drone for:

[0085] ;

[0086] S3.3: Establish geometric relationship equations that include unknown distances, and form a system of linear equations after eliminating the distance parameters;

[0087] In step S3.3, based on spatial geometric relationships, we have:

[0088] ;

[0089] in Infrared guided transmitter The unknown distance to the drone;

[0090] The proportional relationship can be obtained from the above formula, and then eliminating... Two linear equations were then obtained:

[0091] ;

[0092] S3.4: Solve the linear equations using the least squares method to obtain the optimal estimate of the UAV's three-dimensional coordinates;

[0093] In step S3.4, the four infrared guiding transmitters ( A total of The linear equations, rearranged into matrix form:

[0094] ;

[0095] in:

[0096] ;

[0097] for The coefficient matrix, for A constant vector, specifically in the form of:

[0098] ;

[0099] The optimal estimate of the UAV's three-dimensional coordinates is obtained by solving the overdetermined system of equations using the least squares method.

[0100] = .

[0101] 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;

[0102] 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.

[0103] The landing authorization code is a data field containing a list of unique identifiers for the drone currently authorized to land, the list being encoded in an infrared signal frame in a predefined order.

[0104] 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:

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

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

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

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

[0109] 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. In addition, the system can dynamically adjust the landing order, skip abnormal drones, and ensure the overall process proceeds.

[0110] 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;

[0111] 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.

[0112] 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.

[0113] After a drone successfully lands, it sends a "landing and returning" signal to the ground system via short-range wireless communication (such as Bluetooth, NFC, etc.) or wired connection. Once the ground system confirms that all drones in the batch have landed, it updates the status and sends landing clearance codes for the next batch, continuing until all drones have landed.

[0114] An infrared-guided automatic landing system for a swarm of unmanned aerial vehicles (UAVs) includes:

[0115] 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;

[0116] 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;

[0117] The ground control unit is connected to the infrared guidance transmitter for generating landing clearance codes and controlling the content of infrared signals.

[0118] A drone swarm, where each drone 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, 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.

[0120] Taking the landing of a drone swarm in a 50m×50m field as an example:

[0121] 1. System Layout

[0122] Select a flat 50m×50m area as the landing zone, and divide it into 625 cells in a 2m×2m grid. Place a drone housing in the center of each cell, numbered from (1,1) to (25,25).

[0123] An infrared guiding and transmitting device is set up at each of the four corners of the site (coordinates A (0, 0), B (50, 0), C (0, 50), and D (50, 50) respectively), with an installation height of 1m, to ensure that the infrared signal covers the entire airspace.

[0124] Each infrared guiding and transmitting device integrates 9×9=81 infrared transmitting units (high-power infrared LEDs) arranged in a honeycomb pattern, with a wavelength of 940nm and a transmission frequency of 37kHz. Each unit corresponds to a unique 6-bit binary code, which can represent 64 different states, fully meeting the encoding requirements of 81 units.

[0125] 2. Time synchronization and signal transmission

[0126] The four infrared guiding transmitters communicate via a wired connection to achieve time synchronization.

[0127] The system emits infrared signals at a frequency of 50 Hz, with each cycle lasting 20 ms. Four infrared guiding transmitters emit in turn, each occupying a 5 ms window. Within the emission window of each infrared guiding transmitter, its 81 emission units emit sequentially in turn, with each unit emitting for approximately 61.7 μs.

[0128] 0-5ms: The infrared guiding transmitter at corner A starts working, and its 81 LEDs are activated sequentially, with each unit lasting approximately 61.7μs;

[0129] 5-10ms: The infrared guiding transmitter at corner B starts working;

[0130] 10-15ms: The infrared guiding transmitter at corner C starts working;

[0131] 15-20ms: The infrared guiding transmitter at corner D starts working.

[0132] The signal frame structure is: 2-byte boot device code (distinguishing the four corners) + 4-byte landing authorization code (which can accommodate multiple UAV numbers) + 2-byte CRC check code.

[0133] 3. Drone Configuration

[0134] Each drone is equipped with a wide-angle infrared receiver at its bottom, with a field of view greater than 120°, ensuring that it can receive signals from multiple directions simultaneously.

[0135] The onboard processor integrates decoding and positioning algorithms to calculate its own position in real time.

[0136] A camera is mounted on the belly of the drone for low-altitude visual guidance.

[0137] Once the drone receives the signal, it performs the following steps:

[0138] Decode to obtain the boot device code (e.g., A);

[0139] The infrared transmitting unit identifier is calculated based on the received timestamp. For example, if the received time is t=3.2ms, it is determined that it is in the A-angle window (0-5ms), and the offset is 3.2ms → corresponding to the 52nd LED (3.2ms / 61.7μs≈52).

[0140] Combine the sub-spatial domain encoding information (e.g., A, 52), and query the locally stored direction mapping table to obtain the direction angle;

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

[0142] 4. Example of landing process

[0143] Suppose there are 30 drones that need to land, and their chassis numbers have been assigned in advance.

[0144] After the drone swarm returned, it hovered at an altitude of 30 meters.

[0145] The ground control unit assigns four landing strategies based on the chassis grid (25 rows x 25 columns):

[0146] The first batch: odd rows and columns, such as (1,1), (1,3), (3,1), etc.

[0147] The second batch: odd rows and even columns (such as (1,2), (1,4), etc.);

[0148] Third batch: Even rows, odd columns;

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

[0150] First, send the first batch of landing clearance codes, which include the numbers of all odd-numbered drones that are waiting to land (e.g., (1,1), (1,3), (3,1), etc.).

[0151] Before each batch begins, the ground control unit generates a landing authorization code containing the batch's drone ID and broadcasts it via infrared signal. Landing is only initiated if the drone's own ID matches the authorization code.

[0152] When the altitude drops to 2 meters, the drone switches to visual guidance, and the camera recognizes the QR code on the chassis to perform the final stage of precise hovering and landing.

[0153] After landing, the drone sends a landing signal to the ground control unit via a wireless link (such as LoRa). The ground control unit counts and confirms the number of drones. Once all drones in the current batch have landed, it sends a second batch of clearance codes (odd numbers followed by even numbers), and so on, until all drones have landed.

[0154] 5. Exception handling and dynamic scheduling

[0155] If a drone fails to receive a valid infrared signal for three consecutive cycles, or if its ID is not included in the current license code, it will execute a hovering wait strategy and continue to listen for subsequent signals.

[0156] In addition, the ground control unit supports dynamic priority adjustment: for example, when a drone's battery level is below 15%, it can be temporarily added to the next emergency batch to achieve priority landing.

[0157] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

[0158] The embodiments of this invention are intended to cover all such substitutions, modifications, and variations falling within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

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 guidance and transmitting devices are deployed at the four corners of the rectangular landing area. Each infrared guidance and transmitting device includes multiple infrared transmitting units. All infrared transmitting units transmit infrared signals in turn in a time-division multiplexing manner to divide the covered airspace into multiple sub-airspaces with unique codes. S2: After the drone swarm returns to the rectangular landing area, each drone receives infrared signals emitted by four infrared guidance transmitters via its onboard infrared receiver and decodes them to obtain the corresponding sub-airspace coding information. 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, multiple infrared emitting units in each infrared guiding and emitting device are arranged in a honeycomb pattern, and each infrared emitting unit corresponds to a fixed radiation direction. Together with its respective infrared guiding and emitting device, it defines a sub-space domain with a unique code.

3. 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.

4. The method for infrared-guided automatic landing of a drone swarm according to claim 1, characterized in that, In step S2, the infrared signal includes a guidance device code, a landing authorization code, and a verification code. Each UAV receives the infrared signals emitted by the four infrared guidance transmitters through its onboard infrared receiver and decodes the guidance device code in each signal. At the same time, it determines the identifier of the activated infrared transmitter unit 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.

5. 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 vector of direction 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.

6. The method for infrared-guided automatic landing of a drone swarm according to claim 5, 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 can be obtained from the above formula, and then eliminating... Two linear equations were then obtained: ； In step S3.4, the four infrared guiding transmitters ( A total of 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. = 。 7. The method for infrared-guided automatic landing of a drone swarm according to claim 4, 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.

8. The method for infrared-guided automatic landing of a drone swarm according to claim 7, 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.

9. 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.

10. An infrared-guided automatic landing system for a swarm of unmanned aerial vehicles (UAVs) for implementing the method as described in any one of claims 1 to 9, 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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