Method and device for determining landing area of unmanned aerial vehicle, unmanned aerial vehicle and storage medium

Abstract

This invention discloses a method, apparatus, drone, and storage medium for determining the landing area of ​​a drone. The method for determining the landing area includes: upon detecting a forced landing event, determining the drone's operational boundary, and determining a target boundary from the operational boundary; controlling the drone to fly along the target boundary; and determining the landing area while the drone is flying along the target boundary. Controlling the drone to fly along the operational boundary when a forced landing is required makes it easier to find the landing area, solving the problem of long search times or even failure to find a landing area, thus improving the efficiency of drone landing area search and enabling timely forced landing, thereby ensuring the drone's flight safety.

Description

Technical Field

[0001] This invention relates to the field of unmanned aerial vehicle (UAV) technology, and more particularly to a method, apparatus, UAV, and storage medium for determining the landing area of ​​a UAV. Background Technology

[0002] As drone technology matures, drones have been widely used in various fields. For example, drones can perform surveying, plant protection, exploration, aerial photography, and other flight operations according to pre-planned routes.

[0003] In existing technologies, landing points are set on pre-planned flight routes before the drone takes off. After completing its flight mission, the drone returns to the landing point to land, or lands in place after completing its flight mission.

[0004] During drone operations, emergencies may arise requiring an emergency landing, such as low battery, mechanical failure, or sensor malfunction, preventing the drone from reaching the pre-set landing point. Current technology typically involves randomly searching for a suitable landing area from the current location. However, since the environment of the drone's operating area often does not meet landing requirements, existing solutions are inefficient in finding a landing area. This can lead to the drone running out of power and crashing before finding a suitable landing spot, resulting in damage. Summary of the Invention

[0005] This invention provides a method, apparatus, drone, and storage medium for determining the landing area of ​​a drone, so as to improve the efficiency of the drone in finding the landing area and avoid damage to the drone in the event of a forced landing.

[0006] In a first aspect, embodiments of the present invention provide a method for determining the landing area of ​​a drone, applicable to drones equipped with depth sensors and radar, comprising:

[0007] Upon detecting a forced landing event, the operational boundary of the UAV is determined, wherein the operational boundary is the boundary of the UAV's operational area;

[0008] Determine the target boundary from the operation boundary;

[0009] Control the drone to fly along the target boundary;

[0010] The landing area is determined as the UAV flies along the target boundary.

[0011] Optionally, determining the target boundary from the operation boundary includes:

[0012] Obtain the location information of the drone;

[0013] The distance from each operational boundary to the drone is calculated using the drone's location information;

[0014] Use the boundary of the operation with the smallest distance as the target boundary.

[0015] Optionally, determining the target boundary from the operation boundary includes:

[0016] The shortest boundary among the operational boundaries is determined as the target boundary.

[0017] Optionally, methods for determining the drone landing area also include:

[0018] When a landing area cannot be determined along the target boundary, the next target boundary is determined;

[0019] Determine the landing area during flight along the next boundary.

[0020] Optionally, the UAV is equipped with a depth sensor and radar, and determining the landing area during the flight of the UAV along the target boundary includes:

[0021] Control the depth sensor to acquire a depth image of the area covered by the depth sensor and control the radar to acquire the first distance from the UAV to the coverage area;

[0022] Based on the depth image and the first distance, candidate areas whose flatness meets the preset forced landing conditions are determined from the covered area;

[0023] The landing area is determined from the candidate area based on the radar data. The landing area is the area where the penetration thickness of the radar signal is less than a preset thickness and the signal strength of the reflected radar signal is greater than a preset threshold.

[0024] Optionally, the control radar acquires radar data from the UAV to the coverage area, including...

[0025] Obtain the landing area of ​​the drone;

[0026] The coverage area is divided into multiple sub-regions based on the landing area and the depth image;

[0027] The system controls the radar to transmit radar signals to the current sub-region and to receive the echo signals reflected by the radar signals from the current sub-region. The current sub-region is the sub-region directly below the UAV.

[0028] The radar data of the current sub-region is obtained based on the radar signal and the echo signal.

[0029] Optionally, the coverage area includes multiple sub-regions, the radar data includes a first distance from the UAV to the current sub-region, and the step of determining candidate areas whose flatness meets preset landing conditions from the coverage area based on the depth image and the radar data includes:

[0030] For the current sub-region, the depth values ​​of each object point within the current sub-region are obtained based on the depth image;

[0031] Based on the depth values ​​of each object point and the first distance, determine whether the current sub-region meets the preset landing conditions;

[0032] If so, then the current sub-region is determined as a candidate region.

[0033] Optionally, methods for determining the drone landing area also include:

[0034] If it is determined that the current sub-region is not a candidate region, then the drone is controlled to fly to the next sub-region;

[0035] The sub-region directly below the UAV is identified as the current sub-region, and the process returns to the steps of controlling the radar to transmit radar signals to the current sub-region and receiving the echo signals reflected by the radar signals from the current sub-region.

[0036] Optionally, determining whether the current sub-region meets the preset landing conditions based on the depth values ​​of each object point and the first distance includes:

[0037] Calculate the mean and variance of the depth values ​​for each object point within the sub-region;

[0038] Determine the maximum and minimum depth values ​​for each object point within the sub-region;

[0039] Calculate the difference between the mean and the first distance to obtain the first difference;

[0040] When the first difference, variance, maximum value, and minimum value meet the preset landing conditions, it is determined that the sub-region meets the preset landing conditions.

[0041] If the first difference, variance, maximum value and minimum value do not meet the preset landing conditions, the sub-region is determined to not meet the preset landing conditions.

[0042] The preset landing condition is at least one of the following conditions: the first difference is less than a first preset difference threshold, the variance is less than a preset variance threshold, the maximum value is less than a preset maximum threshold, and the minimum value is greater than a preset minimum threshold.

[0043] Optionally, the radar data also includes a second distance from the UAV to the current sub-region, and the acquisition of radar data based on the radar signal and the echo signal includes:

[0044] Based on the echo signal and the radar signal, a first distance and a second distance from the UAV to the current sub-region are determined, where the first distance and the second distance are the distances from the UAV to the first surface and the second surface of the current sub-region, respectively.

[0045] The signal strength of the echo signal reflected from the first surface is obtained based on the echo signal and the radar signal.

[0046] Optionally, the radar data includes a first distance and a second distance from the UAV to a first surface and a second surface of the candidate area, respectively, and the signal strength of the echo signal from the first surface. Determining the landing area from the candidate area based on the radar data includes:

[0047] Calculate the difference between the first distance and the second distance to obtain the second difference;

[0048] Determine whether the second difference is greater than a second preset difference threshold;

[0049] If so, then the candidate region is determined to be a non-landing region, meaning that the penetration thickness of the radar signal is less than the preset thickness.

[0050] If not, determine that the candidate region is a region where the penetration thickness of the radar signal is less than a preset thickness, and determine whether the signal strength is less than a preset strength threshold.

[0051] When the signal strength is greater than a preset strength threshold, the candidate region is determined to be a region where the signal strength of the reflected radar signal is greater than the preset threshold, and the candidate region is the landing region;

[0052] When the signal strength is less than a preset strength threshold, the candidate region is determined to be a region where the signal strength of the reflected radar signal is greater than the preset threshold, and the candidate region is a non-landing region.

[0053] Optionally, methods for determining the drone landing area also include:

[0054] When it is determined that the candidate area is not a landing area, the UAV is controlled to fly to the next sub-area, and the process returns to the steps of controlling the radar to transmit radar signals to the current sub-area and receiving the echo signals reflected by the radar signals from the current sub-area.

[0055] Secondly, embodiments of the present invention provide a device for determining the landing area of ​​a drone, comprising:

[0056] The operation boundary determination module is used to determine the operation boundary of the UAV when a forced landing event is detected. The operation boundary is the boundary of the operation area of ​​the UAV.

[0057] A target boundary determination module is used to determine the target boundary from the operation boundary;

[0058] The flight control module is used to control the UAV to fly along the target boundary;

[0059] A landing area determination module is used to determine the landing area as the UAV flies along the target boundary.

[0060] Optionally, the target boundary determination module includes:

[0061] The location information acquisition submodule is used to acquire the location information of the UAV;

[0062] The first calculation submodule is used to calculate the distance from each operation boundary to the drone using the drone's location information;

[0063] The first target boundary determination submodule is used to select the operation boundary with the smallest distance as the target boundary.

[0064] Optionally, the target boundary determination module also includes:

[0065] The second target boundary determination submodule is used to determine the shortest boundary from the operation boundaries as the target boundary.

[0066] Optionally, the device for determining the drone landing area also includes:

[0067] The next target boundary determination module is used to determine the next target boundary when the landing area cannot be determined along the target boundary;

[0068] The landing area determination module determines the landing area during flight along the next boundary.

[0069] Optionally, the landing area determination module includes:

[0070] The depth image acquisition submodule is used to control the depth sensor to acquire a depth image of the area covered by the depth sensor when a forced landing event is detected.

[0071] The radar data acquisition submodule is used to control the radar to acquire radar data from the UAV to the coverage area;

[0072] The candidate region determination submodule is used to determine candidate regions whose flatness meets preset landing conditions from the coverage area based on the depth image and the radar data;

[0073] The landing area determination submodule is used to determine the landing area from the candidate areas based on the radar data. The landing area is an area where the penetration thickness of the radar signal is less than a preset thickness and the signal strength of the reflected radar signal is greater than a preset threshold.

[0074] Optionally, the coverage area includes multiple sub-regions, the radar data includes a first distance from the UAV to the current sub-region, and the candidate region determination submodule includes:

[0075] The depth value acquisition unit is used to acquire the depth value of each object point in the current sub-region based on the depth image.

[0076] The landing condition determination unit is used to determine whether the current sub-region meets the preset landing conditions based on the depth value of each object point and the first distance.

[0077] The candidate region determination unit is used to determine the current sub-region as a candidate region.

[0078] Optionally, the landing area determination module also includes:

[0079] The first flight control submodule is used to control the UAV to fly to the next sub-region if it is determined that the current sub-region is not a candidate region.

[0080] The first current sub-region determination submodule is used to determine the sub-region directly below the UAV as the current sub-region and return it to the radar signal transceiver submodule.

[0081] Optionally, the landing condition determination unit includes:

[0082] The mean and variance calculation sub-unit is used to calculate the mean and variance of the depth values ​​of each object point within the sub-region;

[0083] The maximum and minimum values ​​determine the sub-unit, which is used to determine the maximum and minimum depth values ​​of each object point within the sub-region;

[0084] The first search calculation subunit is used to calculate the difference between the mean and the first distance to obtain the first difference;

[0085] The landing condition determination subunit is used to determine that a sub-region meets the preset landing conditions when the first difference, variance, maximum value and minimum value meet the preset landing conditions.

[0086] The non-compliance with landing conditions determination subunit is used to determine that a sub-region does not meet the preset landing conditions when the first difference, variance, maximum value and minimum value do not meet the preset landing conditions.

[0087] The preset landing condition is at least one of the following conditions: the first difference is less than a first preset difference threshold, the variance is less than a preset variance threshold, the maximum value is less than a preset maximum threshold, and the minimum value is greater than a preset minimum threshold.

[0088] Optionally, the radar data acquisition unit includes:

[0089] The distance acquisition subunit is used to determine a first distance and a second distance from the UAV to the current sub-region based on the echo signal and the radar signal, wherein the first distance and the second distance are the distances from the UAV to the first surface and the second surface of the current sub-region, respectively;

[0090] The signal strength acquisition subunit is used to acquire the signal strength of the echo signal reflected from the first surface based on the echo signal and the radar signal.

[0091] Optionally, the landing area determination submodule includes:

[0092] The second difference calculation unit is used to calculate the difference between the first distance and the second distance to obtain the second difference.

[0093] A difference judgment unit is used to determine whether the second difference is greater than a second preset difference threshold;

[0094] The first non-landing area determination unit is used to determine that the candidate area is not an area where the penetration thickness of the radar signal is less than a preset thickness, and the candidate area is a non-landing area.

[0095] A signal strength determination unit is used to determine whether the signal strength is less than a preset strength threshold.

[0096] The landing area determination unit is used to determine the candidate area as an area that the radar signal cannot penetrate when the signal strength is greater than a preset strength threshold, and the candidate area is the landing area;

[0097] The second non-landing area determination unit is used to determine that the candidate area is not an area that the radar signal cannot penetrate when the signal strength is less than a preset strength threshold, and the candidate area is a non-landing area.

[0098] Optionally, the landing area determination module also includes:

[0099] The second flight control module is used to control the UAV to fly to the next sub-area when it is determined that the candidate area is not a landing area;

[0100] The second current sub-region determination module is used to determine the sub-region directly below the UAV as the current sub-region and return it to the radar signal transceiver sub-module.

[0101] Thirdly, embodiments of the present invention provide a drone, the drone comprising:

[0102] One or more processors;

[0103] Storage device for storing one or more programs;

[0104] When the one or more programs are executed by the one or more processors, the one or more processors implement the method for determining the landing area of ​​a drone as described in any embodiment of the present invention.

[0105] Fourthly, embodiments of the present invention provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for determining the landing area of ​​a drone as described in any embodiment of the present invention.

[0106] The method for determining the landing area of ​​a drone according to embodiments of the present invention, upon detecting a forced landing event, first determines the drone's operational boundary and then determines the target boundary, controlling the drone to fly along the target boundary. During the drone's flight along the target boundary, depth sensors and radar are used to acquire ground data to determine the landing area. This method, by controlling the drone to fly along the operational boundary when a forced landing is required, makes it easier to find the landing area. Since the operational boundary is the boundary of the operational area, such as the boundary of flat, hard-surfaced farmland suitable for forced landing, controlling the drone to fly along the operational boundary makes it easier to find the landing area. This solves the problem of long search times or even failure to find a landing area, which prevents the drone from landing in time, thus improving the efficiency of the drone in finding the landing area and ensuring the drone's flight safety. Attached Figure Description

[0107] Figure 1 This is a flowchart of the steps of a method for determining the landing area of ​​a drone according to Embodiment 1 of the present invention;

[0108] Figure 2 This is a flowchart illustrating the steps of a method for determining a drone landing area according to Embodiment 2 of the present invention.

[0109] Figure 3A This is a flowchart illustrating the steps of a method for determining a drone landing area according to Embodiment 3 of the present invention.

[0110] Figure 3B This is a schematic diagram of the perspective of the depth sensor in an embodiment of the present invention;

[0111] Figure 3C This is a schematic diagram of radar ranging in an embodiment of the present invention;

[0112] Figure 4This is a schematic diagram of a drone forced landing device provided in Embodiment 4 of the present invention. Detailed Implementation

[0113] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0114] Example 1

[0115] Figure 1 This is a flowchart illustrating the steps of a method for determining a drone landing area according to Embodiment 1 of the present invention. This embodiment is applicable to emergency landings of drones. The method can be executed by a drone landing area determination device, which can be implemented in software and / or hardware and integrated into the drone, such as... Figure 1 As shown, the method specifically includes the following steps:

[0116] S101. When a forced landing event is detected, determine the operating boundaries of the drone.

[0117] In this embodiment of the invention, a forced landing event can be an event that prevents the drone from continuing normal flight, such as mechanical failure, insufficient power, or sensor failure. A forced landing event can also occur when a user sends a forced landing command to the drone via a remote controller, and the drone generates a forced landing event based on the command. The operational boundary is the boundary of the drone's operational area; for example, the operational area can be a field, and the operational boundary is the boundary of that field.

[0118] Specifically, the operation boundary can be determined during the surveying of the operation area or based on the previous operation route of the drone. When a forced landing event is detected, only the location information of the operation boundary needs to be called.

[0119] S102. Determine the target boundary from the work boundary.

[0120] For example, in one embodiment of the present invention, the boundary of the work area that is closest to the current position of the drone can be selected as the target boundary. Specifically, when a forced landing event is detected, the location information of the drone can be obtained through GPS, RTK, etc. Based on the current location information of the drone and the location information of the work boundary, the distance from each work boundary to the drone is calculated. After obtaining the distance from each work boundary to the drone, the work boundary closest to the drone is selected as the target boundary.

[0121] For example, in another embodiment of the present invention, the length of each work boundary can be determined, and the work boundary with the shortest length can be used as the target boundary. The length information of each work boundary can be obtained in advance by surveying and stored in memory.

[0122] S103. Control the drone to fly along the target boundary.

[0123] After determining the target boundary, control the drone to fly towards the target boundary, and when the drone reaches above the target boundary, control the drone to fly along the target boundary.

[0124] S104. Determine the landing area while the UAV is flying along the target boundary.

[0125] In practical applications, drones are equipped with depth sensors and radar. Both the depth sensor and radar can be pointed downwards from the drone. The depth sensor has a certain field of view and can acquire depth images of the area on the ground that its field of view can cover.

[0126] Optionally, the depth sensor can be a camera, which can be one of a binocular camera, a monocular camera, or a multi-view camera. A depth image is generated by calculating the depth of the image captured by the camera. Alternatively, the depth sensor can be an array of Time-of-Flight (TOF) sensors. An array of TOF is a type of photoradar system that emits light pulses from a transmitter to its coverage area. The receiver can determine the distance from a point in the coverage area to the array of TOF by calculating the travel time of the light pulse from the transmitter to the coverage area and back to the receiver, thereby generating a depth image. The depth sensor can also be other distance-measuring devices; this embodiment of the invention does not limit the type of depth sensor. Additionally, the radar can be a ranging radar used to measure the distance from the drone to the ground directly below it. For example, it can be ultrasonic or millimeter-wave radar. In this embodiment of the invention, the ground data can be the depth image acquired by the depth sensor, the distance obtained by radar ranging, and the radar echo signal strength, etc.

[0127] In this embodiment of the invention, an image of the covered area is acquired using a depth sensor to obtain a depth image. The depth value of each object point within the covered area is determined using the depth image. The depth value corresponds to the distance from each pixel point on the covered area to the drone. Thus, the distance from each pixel point on the depth image to the drone is obtained. Based on the depth value and the distance measured by radar, a sub-region within the covered area whose flatness meets the forced landing conditions is identified as a candidate region. The distance from the drone to the first surface and the distance from the drone to the second surface of the candidate region are obtained by radar. The first surface can be a vegetation surface, and the second surface can be the ground. If the difference between the distance from the drone to the first surface and the distance from the drone to the second surface of the candidate region, i.e., the vegetation height is less than a preset value or there is no vegetation cover, then the candidate region is determined to meet the forced landing requirements (e.g., low grass). Otherwise, it does not meet the forced landing requirements. For candidate regions with very low vegetation or even no vegetation cover, the signal strength of the radar echo signal from the second surface can be used to determine whether the candidate region is a suitable landing area. When both the vegetation height and the hardness of the candidate region meet the preset requirements, the candidate region is determined as a suitable landing area.

[0128] Optionally, when a landing area cannot be determined along the target boundary, i.e. when a suitable landing area for forced landing cannot be found by flying along the current target boundary, the next target boundary is redefined, and the UAV is controlled to fly along the next target boundary. The landing area is determined during the flight along the next boundary, and so on, until a suitable landing area for forced landing is found.

[0129] Once the landing area is determined, the drone can be controlled to make an emergency landing within that area.

[0130] The method for determining the landing area of ​​a drone according to embodiments of the present invention, upon detecting a forced landing event, first determines the drone's operational boundary and target boundary, controls the drone to fly along the target boundary, and determines the landing area during the drone's flight along the target boundary. This method, by controlling the drone to fly along the operational boundary when a forced landing is required, makes it easier to find a suitable landing area. Since the operational boundary is the boundary of the operational area, such as the boundary of flat, hard-surfaced farmland suitable for forced landing, controlling the drone to fly along the operational boundary makes it easier to find a suitable landing area. This solves the problem of drones taking a long time to find a landing area, or even failing to find a landing area at all, thus preventing timely forced landings. It improves the efficiency of drones in finding landing areas, enabling timely forced landings and ensuring the flight safety of the drone.

[0131] Example 2

[0132] Figure 2This is a flowchart illustrating the steps of a method for determining a drone landing area according to Embodiment 2 of the present invention. This embodiment optimizes Embodiment 1 and provides an exemplary method for determining the landing area. Specifically, as shown... Figure 2 As shown, the method of this embodiment of the invention may include the following steps:

[0133] S201. When a forced landing event is detected, determine the operating boundaries of the UAV.

[0134] S202. Determine the target boundary from the work boundary.

[0135] S203, Control the drone to fly along the target boundary.

[0136] S204. Control the depth sensor to acquire depth images of the area covered by the depth sensor.

[0137] In practical applications, drones are equipped with depth sensors and radar. Both the depth sensor and radar can be pointed downwards from the drone. The depth sensor has a certain field of view and can acquire depth images of the area it covers on the ground.

[0138] Optionally, the depth sensor can be a camera, which can be one of a binocular camera, a monocular camera, or a multi-view camera. The depth image is generated by calculating the depth of the image captured by the camera. For example, for a monocular camera, when the focal length of the camera is known, the distance from the object point to the drone is calculated by combining the coordinates of the drone and the coordinates of the pixels in the captured image, which is the depth value of the object point relative to the drone, using the principle of triangulation. For a binocular camera, the depth value from the object point to the drone can be calculated by the principle of binocular ranging, and a depth image can be generated based on the depth value.

[0139] The depth sensor can also be an array of Time of Flight (TOF), which is a type of photoradar system. The array of TOF can emit light pulses from the transmitter to its coverage area, and the receiver can determine the distance from the object point in the coverage area to the array of TOF by calculating the travel time of the light pulse from the transmitter to the coverage area and back to the receiver, thereby generating a depth image. The depth sensor can also be other devices capable of measuring distances. The embodiments of the present invention do not limit the type of depth sensor.

[0140] S205, control the radar to acquire radar data of the UAV to the coverage area.

[0141] In this embodiment of the invention, the radar can be a ranging radar used to measure the distance from the drone to the ground directly below the drone. For example, it can be an ultrasonic radar or a millimeter-wave radar. This embodiment of the invention does not limit the type of radar.

[0142] Radar data can be either distance or signal strength. When acquiring radar data, the radar can be controlled to transmit radar signals to the coverage area and receive echo signals reflected from the coverage area. The distance is calculated based on the radar signal and the echo signal. Optionally, the radar signal and the echo signal can be mixed to generate a difference frequency signal, and the distance value can be calculated based on the difference frequency signal. Of course, in practical applications, the distance can also be estimated based on the time difference between transmitting and receiving the radar signal. This embodiment of the invention does not limit the method of radar distance acquisition.

[0143] In practical applications, for areas covered by vegetation, both the plant surface and the ground reflect radar signals to form echo signals. Therefore, the radar data can include the first distance from the UAV to the first surface of the current sub-region below, and the second distance from the UAV to the second surface of the current sub-region below. It can also include the signal strength of the radar signal reflected from the first surface. Specifically, a difference frequency signal can be generated from the radar signal and the echo signal. This difference frequency signal can then be sampled, subjected to FFT transformation, and detected to determine the signal frequency and amplitude corresponding to the first and second surfaces, respectively. The first and second distances are calculated based on the corresponding signal frequencies, and the signal amplitude at the frequency point corresponding to the first surface is used as the signal strength.

[0144] For areas not covered by vegetation, a distance, i.e., the first distance, can be obtained through radar signals and echo signals, and the signal strength of the echo signal can also be obtained.

[0145] S206. Based on the depth image and radar data, determine the candidate areas whose flatness meets the preset landing conditions from the coverage area.

[0146] Specifically, each pixel in the depth image is associated with a depth value, which corresponds to the distance from the object point in the coverage area of ​​the depth sensor to the drone. Thus, the depth value of the pixel in the depth image corresponding to the object point in the coverage area to the drone can be obtained.

[0147] For the coverage area of ​​the depth sensor, a region to be determined can be selected as the current sub-region based on the landing area required by the drone. For example, if the area below the drone is determined as the current sub-region, the radar can be controlled to acquire radar data from the drone to the current sub-region. This radar data can include the first distance from the drone to the surface of the current sub-region. The flatness of the current sub-region can be determined based on the depth values ​​of each object point in the current sub-region and the first distance from the drone to the current sub-region measured by the radar. This flatness expresses the distance from each object point in the current sub-region to the drone.

[0148] Optionally, the flatness can be expressed by multiple parameters, such as the difference between the mean depth value and the first distance, or the variance of the depth value, obtaining the maximum and minimum depth values ​​as the flatness, or a combination of two or more of the above as the flatness, etc. When the flatness meets the preset landing conditions, the current sub-region is determined as a candidate region that meets the landing conditions. Otherwise, the UAV continues to fly to the next region to be determined as the current sub-region, and after obtaining the first distance of the current sub-region, it determines whether it meets the preset landing conditions, until a sub-region whose flatness meets the preset landing conditions is determined as a candidate region within the coverage area.

[0149] S207. Determine the landing area from the candidate areas based on radar data.

[0150] The landing area is the region where the penetration thickness of the radar signal is less than the preset thickness and the signal strength of the reflected radar signal is greater than the preset threshold.

[0151] Specifically, for candidate areas whose flatness meets the preset landing conditions, the first distance represents the closest distance from the candidate area to the UAV. For example, the first distance could be the distance from the top surface of the plants in the candidate area to the UAV. If the radar data includes a second distance, it indicates that the candidate area is covered by plants. The second distance represents the farthest distance from the candidate area to the UAV. For example, it could be the distance from the ground in the candidate area to the UAV. Thus, it can be determined whether the candidate area is covered by plants based on the first and second distances, that is, whether the candidate area has a penetrating layer that can be penetrated by radar signals. Optionally, the difference between the first and second distances can be calculated. If the difference is less than a preset value, it means that the thickness of the penetrating layer of radar signals is very small or even cannot be penetrated, indicating that the plants on the candidate area are very short or there are no plants covering it (the difference is 0). If the difference is greater than a preset value, it means that the candidate area is covered by tall plants, that is, the penetrating layer of radar signals is thick and cannot be used as a landing area.

[0152] For candidate areas with very short vegetation or no vegetation cover, i.e., candidate areas where the radar signal penetration layer is very thin or even impenetrable, the signal strength of the radar signal echo can be used to determine whether the candidate area is a suitable landing area with suitable hardness, such as solid ground. Specifically, when the signal strength is less than a preset strength threshold, the candidate area can be determined to be a softer surface such as water or swamp that reflects radar signals weakly. This candidate area is not an area where the radar signal strength reflects the radar signal is greater than the preset threshold and cannot be used as a landing area. Otherwise, it is an area where the radar signal strength reflects the radar signal is greater than the preset threshold, and is a relatively hard area suitable for landing and can be used as a landing area.

[0153] Once the landing area is determined, the drone can be controlled to land in the landing area; otherwise, the drone can be controlled to fly to the next sub-area within the coverage area, and the radar can be controlled to acquire radar data of that sub-area until the landing area is determined.

[0154] This invention first determines candidate areas whose flatness meets preset landing conditions based on depth images and radar data. Then, it determines candidate areas whose radar signal penetration thickness is less than a preset thickness and whose reflected radar signal signal strength is greater than a preset threshold as landing areas based on radar data. This fully considers the flatness of the landing area and the landing environment, avoiding the drone from landing on water, trees, or uneven ground, ensuring the drone can land safely and reducing damage during landing.

[0155] Example 3

[0156] Figure 3A This is a flowchart illustrating the steps of a method for determining a drone landing area according to Embodiment 3 of the present invention. This embodiment optimizes Embodiment 1 and provides an exemplary method for determining candidate areas and landing areas. Specifically, as shown... Figure 3A As shown, the method of this embodiment of the invention may include the following steps:

[0157] S301. When a forced landing event is detected, determine the operating boundaries of the drone.

[0158] S302. Determine the target boundary from the work boundary.

[0159] S303, Control the drone to fly along the target boundary.

[0160] S304. Control the depth sensor to acquire depth images of the area covered by the depth sensor.

[0161] S305, Obtain the landing area of ​​the drone.

[0162] The landing area of ​​a drone is related to its external dimensions. The required landing area can be obtained by shifting a safe distance outward from the external dimensions. The area of ​​this required landing area is the landing area of ​​the drone.

[0163] S306. The coverage area is divided into multiple sub-regions based on the landing area and depth images.

[0164] Specifically, the area of ​​the coverage region is calculated based on the depth image. When the area of ​​the coverage region is greater than the landing area, the coverage region is divided into multiple continuous sub-regions with an area equal to the landing area. When the area of ​​the coverage region is less than the landing area, the coverage region is treated as a sub-region.

[0165] like Figure 3BAs shown, the depth sensor is a camera, the camera's field of view is a, and the drone's height from the coverage area is h1. The height h1 can be obtained by measuring the distance from the drone to the coverage area using radar. The side length of the coverage area can then be determined based on trigonometric relationships, thereby determining the area of ​​the coverage area. The coverage area can then be divided into multiple continuous sub-regions with areas equal to the drone's landing area. If the area of ​​the coverage area is smaller than the drone's landing area due to the drone's height h1 being too low, the entire coverage area can be directly treated as a single sub-region.

[0166] S307, Control the radar to transmit radar signals to the current sub-region and receive echo signals reflected from the radar signals in the current sub-region.

[0167] Specifically, the sub-region directly below the drone is the current sub-region. The drone can transmit radar signals to the current sub-region and receive the echo signals reflected by the radar signals from the current sub-region.

[0168] S308: Acquire radar data based on radar signals and echo signals.

[0169] In this embodiment of the invention, a first distance and a second distance from the UAV to the current sub-region can be determined based on the echo signal and the radar signal, wherein the first distance and the second distance are the distances from the UAV to the first surface and the second surface of the current sub-region, respectively; and the signal strength of the echo signal reflected by the first surface is obtained based on the echo signal and the radar signal.

[0170] Specifically, a difference frequency signal can be generated using radar signals and echo signals. This difference frequency signal can then be sampled, subjected to FFT transformation, and then detected. If the current sub-region is not covered by vegetation, the distance from the first surface of the current sub-region to the drone can be determined as the first distance. If the current sub-region is covered by vegetation, the distance from the second surface of the current sub-region to the drone can be determined as the second distance. For example... Figure 3CAs shown, for a sub-region, the first distance h1 and the second distance h2 from the UAV to the sub-region can be obtained by radar. That is, in practical applications, the radar signal is a continuous periodic signal. If the sub-region is covered by plants, part of the radar signal emitted by the radar is reflected once by the top surface of the plants (first surface) to form an echo signal, and part of the radar signal penetrates the plant layer and reaches the ground, and is reflected by the ground (second surface) to form an echo signal. The radar receives these two parts of the echo signal as the echo signal, and then uses the radar signal and the received echo signal to generate a difference frequency signal. The difference frequency signal is sampled and FFT transformed to obtain a swept frequency signal. The swept frequency signal has multiple frequency points, each with a signal frequency and a signal amplitude. After the swept frequency signal is detected, the frequency points corresponding to the first surface and the second surface can be determined from the swept frequency signal. The distance is calculated based on the signal frequency of the corresponding frequency point, and the signal amplitude also represents the signal strength. The signal strength of the radar signal reflected by the first surface can be obtained.

[0171] S309. For the current sub-region, obtain the depth values ​​of each object point within the current sub-region based on the depth image.

[0172] In this embodiment of the invention, the sub-region below the drone can be taken as the current sub-region, and the pixel corresponding to the current sub-region can be determined from the depth image, thereby obtaining the depth value of the object point corresponding to the pixel in the current sub-region through the pixel corresponding to the current sub-region.

[0173] S310. Based on the depth value and first distance of each object point, determine whether the flatness of the current sub-region meets the preset landing conditions. If yes, execute S311; otherwise, execute S312.

[0174] In this embodiment of the invention, for the current sub-region, the mean and variance of the depth values ​​of all objects within the sub-region can be calculated, and the difference between the mean and the first distance can be calculated to obtain the first difference, and the maximum and minimum values ​​of the depth values ​​of each object within the sub-region can be determined.

[0175] The first distance is the distance from the drone to the current sub-region, as obtained by the radar when the drone is directly above the current sub-region. The mean is the arithmetic mean of the depth values ​​of all objects in the sub-region. The variance represents the fluctuation range of the depth values ​​of all objects in the sub-region. The maximum depth value represents the distance from the lowest point in the sub-region to the drone, and the minimum depth value represents the distance from the highest point in the sub-region to the drone.

[0176] In this embodiment of the invention, the preset landing condition is at least one of the following conditions: the first difference is less than the first preset difference threshold, the variance is less than the preset variance threshold, the maximum value is less than the preset maximum threshold, and the minimum value is greater than the preset minimum threshold.

[0177] Specifically,

[0178] Determine whether the difference between the mean and the first distance measured by the radar is less than the first preset difference threshold. If it is, it means that the current sub-region is relatively flat. If not, it means that the current sub-region is uneven.

[0179] Determine whether the variance is less than the preset variance threshold. If it is, it means that the current sub-region depth value fluctuates less; otherwise, it means that the current sub-region depth value fluctuates more.

[0180] Determine if the minimum depth value is greater than the preset minimum threshold. If it is, it means there are no small protruding objects in the current sub-region. If not, it means there may be small protruding objects in the current sub-region, such as telephone poles erected on flat ground or bare tree trunks.

[0181] Determine if the maximum depth value is less than the preset maximum threshold. If it is, it means there are no deep pits in the current sub-region. Otherwise, it means there may be large or deep pits in the current sub-region.

[0182] In the above conditions, the mean and variance provide a global assessment of the flatness of the entire sub-region, while the maximum and minimum depth values ​​provide a local assessment of the flatness of the sub-region. In practical applications, at least one of the mean, variance, maximum, and minimum values ​​can be used to determine whether the flatness of the current sub-region meets the preset landing conditions. If yes, proceed to step S311; otherwise, proceed to step S312.

[0183] It should be noted that the preset difference threshold, preset variance threshold, preset maximum threshold, and preset minimum threshold are related to the physical characteristics of the UAV itself. For example, when the UAV landing has low requirements for ground flatness, the preset difference threshold and preset variance threshold can be larger, and vice versa. Those skilled in the art can determine the above thresholds based on the physical characteristics of the UAV itself. The embodiments of the present invention do not limit the size and value of each threshold.

[0184] S311. Determine the current sub-region as a candidate region.

[0185] If the flatness of the current sub-region meets the preset landing conditions through at least one of the mean, variance, maximum and minimum values, it indicates that the current sub-region is relatively flat and can be determined as a candidate region. Execute S313 to further confirm whether the candidate region can be used as a landing region.

[0186] S312. Determine that the current sub-region is not a candidate region, and return to S307.

[0187] If the flatness of the current sub-region does not meet the preset landing conditions based on at least one of the mean, variance, maximum, and minimum values, it means that the current sub-region does not meet the landing conditions and landing in the current sub-region may damage the drone. The current sub-region cannot be used as a candidate region. Then, return to S307, traverse the coverage area, control the drone to fly to the next sub-region, and use the next sub-region as the current sub-region. That is, repeat S307-S310 until a candidate region is determined.

[0188] In this embodiment of the invention, after dividing the coverage area into multiple sub-regions based on the drone's landing area, the depth data of the sub-regions is determined based on the depth image. Then, each sub-region is traversed. During the traversal, the flatness of the sub-region is determined based on the depth value of each object point in the sub-region and the first distance from the drone to the sub-region to determine whether the flatness of the sub-region meets the preset landing conditions. This determines the candidate areas where the flatness meets the landing conditions, avoiding the drone from landing in uneven areas, ensuring the safe landing of the drone, and reducing the damage during drone landing.

[0189] S313. Calculate the difference between the first distance and the second distance to obtain the second difference.

[0190] like Figure 3C As shown, the difference between the second distance h2 and the first distance h1 is the height of the plant, that is, the second difference is the height of the plant, which is also the penetration thickness of the radar signal.

[0191] Of course, when the radar data only contains the first distance, the candidate area is determined to be unpenetrable by the radar signal, that is, the penetration thickness of the radar signal is 0, which is an area with a penetration thickness less than the preset thickness. Therefore, S313 does not need to be executed, and S316 is executed directly.

[0192] S314. Determine whether the second difference is greater than the second preset difference threshold. If yes, execute S315; otherwise, execute S316.

[0193] In practical applications, the second difference represents the height of the plants in the candidate area, i.e., the penetration thickness of the radar signal. Since the plant height in this candidate area is relatively uniform, the depth sensor and radar confirm that this area is relatively flat. Therefore, it is necessary to exclude candidate areas covered by plants. Specifically, the second difference can be compared with a second preset difference threshold. The second preset difference threshold can be set such that when the candidate area is covered by plants, the height of those plants does not affect the drone's landing height; for example, short plants such as turf will not cause damage to the drone's landing. When the second difference is greater than the second preset difference threshold, step S315 is executed; when the second difference is less than the second preset difference threshold, step S316 is executed.

[0194] S315. Determine the candidate area as a non-landing area and return to S307.

[0195] If the second difference is greater than the second preset difference threshold, it means that the candidate area is covered by tall plants, which will cause damage to the drone's landing. Therefore, the candidate area is not suitable for landing and is a non-landing area. Then, return to S307 to redetermine the candidate area.

[0196] The system obtains the first and second distances from the candidate area to the drone using radar, calculates the difference between the first and second distances, and compares this difference with a preset difference threshold. If the difference is greater than the preset difference threshold, the candidate area is determined to be an area where the radar signal penetration thickness is less than a preset thickness. This candidate area is a non-landing area. This excludes relatively flat candidate areas that are covered by tall vegetation, thus avoiding the problem of drone loss caused by landing in forests, farmland, or other areas. This ensures safe drone landing and reduces drone landing losses.

[0197] S316. Determine whether the signal strength is less than a preset strength threshold.

[0198] If the second difference is less than the second preset difference threshold, it indicates that the candidate region is a region where the penetration thickness of the radar signal is less than the preset thickness. This candidate region is an area covered by low vegetation, or bare ground without vegetation, or a water surface, swamp, etc. For example, when the candidate region is bare ground without vegetation, a water surface, or a swamp, the first distance and the second distance are equal, so the difference can be 0. To exclude candidate regions that are water surfaces or swamps, the characteristic that the reflection intensity of radar signals is weaker in water surfaces or relatively soft swamps can be used to determine whether the signal strength of the echo signal is less than the preset strength threshold. If yes, execute S318; otherwise, execute S317.

[0199] S317. The candidate area is determined as the landing area.

[0200] If the signal strength of the echo signal is greater than the preset strength threshold, it means that the echo signal is formed by reflection from a relatively hard surface, with little signal loss and a high signal strength. In other words, the candidate area is a relatively hard ground, suitable for drone landing, and this candidate area is the landing area.

[0201] S318. The candidate area is determined to be a non-landing area.

[0202] If the signal strength of the echo signal is less than the preset strength threshold, it means that the echo signal is formed by reflection from a relatively soft surface, resulting in significant signal loss and low signal strength. In other words, the candidate area is a relatively soft water surface or swamp area, which is not suitable for drone landing. Therefore, the candidate area is a non-landing area.

[0203] After determining the candidate area as the landing area, the drone can be controlled to land in the landing area; otherwise, the drone is controlled to fly to the next sub-area covered by the depth sensor, which is then used as the current sub-area, and the process returns to S307.

[0204] In this embodiment of the invention, candidate areas whose flatness meets the landing conditions are first determined from the coverage area using a first distance from the depth sensor and radar data. For relatively flat candidate areas, the radar data also includes candidate areas with a second distance. When the difference between the second distance and the first distance is greater than a preset difference threshold, the area where the radar signal penetration thickness is greater than a preset thickness is determined, i.e., the candidate area is determined to be an area covered by tall vegetation, avoiding the drone from landing in forests or farmland and reducing damage during drone landing. Furthermore, when the difference between the second distance and the first distance is less than a preset difference threshold, the candidate area is determined to be an area where the radar signal penetration thickness is less than a preset thickness. If the signal strength of the echo signal is less than a preset strength threshold, the candidate area is determined to be an area where the radar signal reflection is weak, such as water or swamp, i.e., the candidate area is an area where the signal strength is greater than a preset threshold. Finally, the candidate areas where the radar signal penetration thickness is less than the preset thickness and the reflected radar signal strength is greater than the preset threshold can be determined as landing areas, avoiding the drone from landing in relatively soft areas such as water or swamp, further ensuring the landing safety of the drone and reducing damage during drone landing.

[0205] Example 4

[0206] Figure 4 This is a schematic diagram of the structure of a device for determining the landing area of ​​a drone according to Embodiment 4 of the present invention. Figure 4 As shown, the device for determining the landing area of ​​a drone in an embodiment of the present invention may specifically include:

[0207] The operation boundary determination module 401 is used to determine the operation boundary of the UAV when a forced landing event is detected, wherein the operation boundary is the boundary of the operation area of ​​the UAV;

[0208] The target boundary determination module 402 is used to determine the target boundary from the operation boundary;

[0209] Flight control module 403 is used to control the UAV to fly along the target boundary;

[0210] The landing area determination module 404 is used to determine the landing area during the flight of the UAV along the target boundary.

[0211] Optionally, the target boundary determination module 402 includes:

[0212] The location information acquisition submodule is used to acquire the location information of the UAV;

[0213] The first calculation submodule is used to calculate the distance from each operation boundary to the drone using the drone's location information;

[0214] The first target boundary determination submodule is used to select the operation boundary with the smallest distance as the target boundary.

[0215] Optionally, the target boundary determination module also includes:

[0216] The second target boundary determination submodule is used to determine the shortest boundary from the operation boundaries as the target boundary.

[0217] Optionally, the device for determining the drone landing area also includes:

[0218] The next target boundary determination module is used to determine the next target boundary when the landing area cannot be determined along the target boundary;

[0219] The landing area determination module determines the landing area during flight along the next boundary.

[0220] Optionally, the UAV is equipped with a depth sensor and radar, and the landing area determination module 404 includes:

[0221] The depth image acquisition submodule is used to control the depth sensor to acquire a depth image of the area covered by the depth sensor when a forced landing event is detected.

[0222] The radar data acquisition submodule is used to control the radar to acquire radar data from the UAV to the coverage area;

[0223] The candidate region determination submodule is used to determine candidate regions whose flatness meets preset landing conditions from the coverage area based on the depth image and the radar data;

[0224] The landing area determination submodule is used to determine the landing area from the candidate areas based on the radar data. The landing area is an area where the penetration thickness of the radar signal is less than a preset thickness and the signal strength of the reflected radar signal is greater than a preset threshold.

[0225] Optionally, the coverage area includes multiple sub-regions, the radar data includes a first distance from the UAV to the current sub-region, and the candidate region determination submodule includes:

[0226] The depth value acquisition unit is used to acquire the depth value of each object point in the current sub-region based on the depth image.

[0227] The landing condition determination unit is used to determine whether the current sub-region meets the preset landing conditions based on the depth value of each object point and the first distance.

[0228] The candidate region determination unit is used to determine the current sub-region as a candidate region.

[0229] Optionally, the landing area determination module 404 also includes:

[0230] The first flight control submodule is used to control the UAV to fly to the next sub-region if it is determined that the current sub-region is not a candidate region.

[0231] The first current sub-region determination submodule is used to determine the sub-region directly below the UAV as the current sub-region and return it to the radar signal transceiver submodule.

[0232] Optionally, the landing condition determination unit includes:

[0233] The mean and variance calculation sub-unit is used to calculate the mean and variance of the depth values ​​of each object point within the sub-region;

[0234] The maximum and minimum values ​​determine the sub-unit, which is used to determine the maximum and minimum depth values ​​of each object point within the sub-region;

[0235] The first search calculation subunit is used to calculate the difference between the mean and the first distance to obtain the first difference;

[0236] The landing condition determination subunit is used to determine that a sub-region meets the preset landing conditions when the first difference, variance, maximum value and minimum value meet the preset landing conditions.

[0237] The non-compliance with landing conditions determination subunit is used to determine that a sub-region does not meet the preset landing conditions when the first difference, variance, maximum value and minimum value do not meet the preset landing conditions.

[0238] The preset landing condition is at least one of the following conditions: the first difference is less than a first preset difference threshold, the variance is less than a preset variance threshold, the maximum value is less than a preset maximum threshold, and the minimum value is greater than a preset minimum threshold.

[0239] Optionally, the radar data acquisition unit includes:

[0240] The distance acquisition subunit is used to determine a first distance and a second distance from the UAV to the current sub-region based on the echo signal and the radar signal, wherein the first distance and the second distance are the distances from the UAV to the first surface and the second surface of the current sub-region, respectively;

[0241] The signal strength acquisition subunit is used to acquire the signal strength of the echo signal reflected from the first surface based on the echo signal and the radar signal.

[0242] Optionally, the landing area determination submodule includes:

[0243] The second difference calculation unit is used to calculate the difference between the first distance and the second distance to obtain the second difference.

[0244] A difference judgment unit is used to determine whether the second difference is greater than a second preset difference threshold;

[0245] The first non-landing area determination unit is used to determine that the candidate area is not an area where the penetration thickness of the radar signal is less than a preset thickness, and the candidate area is a non-landing area.

[0246] A signal strength determination unit is used to determine whether the signal strength is less than a preset strength threshold.

[0247] The landing area determination unit is used to determine the candidate area as an area that the radar signal cannot penetrate when the signal strength is greater than a preset strength threshold, and the candidate area is the landing area;

[0248] The second non-landing area determination unit is used to determine that the candidate area is not an area that the radar signal cannot penetrate when the signal strength is less than a preset strength threshold, and the candidate area is a non-landing area.

[0249] Optionally, the landing area determination module 404 also includes:

[0250] The second flight control module is used to control the UAV to fly to the next sub-area when it is determined that the candidate area is not a landing area;

[0251] The second current sub-region determination module is used to determine the sub-region directly below the UAV as the current sub-region and return it to the radar signal transceiver sub-module.

[0252] The above-mentioned device for determining the landing area of ​​a drone can execute the method for determining the landing area of ​​a drone provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of executing the method.

[0253] This invention also provides a drone, which includes: one or more processors; and a storage device for storing one or more programs, which, when executed by the one or more processors, enable the one or more processors to implement the drone landing area determination method described in any embodiment of this invention.

[0254] This invention also provides a computer-readable storage medium, wherein the instructions in the storage medium, when executed by a device processor, enable the drone to perform the method for determining the drone landing area as described in the above method embodiments.

[0255] It should be noted that the embodiments of the device, drone, and storage medium are basically similar to the method embodiments, so the description is relatively simple. For relevant details, please refer to the description of the method embodiments.

[0256] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a robot, personal computer, server, or network device, etc.) to execute the method for determining the landing area of ​​the UAV as described in any embodiment of the present invention.

[0257] It is worth noting that the various units and modules included in the above-mentioned device for determining the landing area of ​​the drone are only divided according to functional logic, but are not limited to the above division, as long as they can achieve the corresponding functions; in addition, the specific names of each functional unit are only for easy differentiation and are not used to limit the scope of protection of this invention.

[0258] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution device. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0259] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0260] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A method for determining the landing area of ​​a drone, characterized in that, include: Upon detecting a forced landing event, the operational boundary of the UAV is determined, wherein the operational boundary is the boundary of the UAV's operational area; Determine the target boundary from the operation boundary; Control the drone to fly along the target boundary; The landing area is determined as the UAV flies along the target boundary. Determining the target boundary from the work boundary includes: Obtain the location information of the drone; The distance from each operational boundary to the drone is calculated using the drone's location information; Use the boundary of the operation with the smallest distance as the target boundary.

2. The method for determining the landing area of ​​a drone as described in claim 1 further includes: When a landing area cannot be determined along the target boundary, the next target boundary is determined; Determine the landing area during flight along the next boundary.

3. The method for determining the landing area of ​​a UAV as described in claim 1, characterized in that, The drone is equipped with a depth sensor and radar. Determining the landing area during the drone's flight along the target boundary includes: Control the depth sensor to acquire depth images of the area covered by the depth sensor; The control radar acquires radar data of the UAV to the coverage area; Based on the depth image and the radar data, candidate areas whose flatness meets the preset landing conditions are determined from the coverage area; The landing area is determined from the candidate area based on the radar data. The landing area is the area where the penetration thickness of the radar signal is less than a preset thickness and the signal strength of the reflected radar signal is greater than a preset threshold.

4. The method for determining the landing area of ​​a UAV as described in claim 3, characterized in that, The control radar acquires radar data from the UAV to the coverage area, including... Obtain the landing area of ​​the drone; The coverage area is divided into multiple sub-regions based on the landing area and the depth image; The system controls the radar to transmit radar signals to the current sub-region and to receive the echo signals reflected by the radar signals from the current sub-region. The current sub-region is the sub-region directly below the UAV. The radar data of the current sub-region is obtained based on the radar signal and the echo signal.

5. The method for determining the landing area of ​​a UAV as described in claim 4, characterized in that, The coverage area includes multiple sub-regions, and the radar data includes a first distance from the UAV to the current sub-region. The step of determining candidate regions whose flatness meets preset landing conditions from the coverage area based on the depth image and the radar data includes: For the current sub-region, the depth values ​​of each object point within the current sub-region are obtained based on the depth image; Based on the depth values ​​of each object point and the first distance, determine whether the current sub-region meets the preset landing conditions; If so, then the current sub-region is determined as a candidate region.

6. The method for determining the landing area of ​​a UAV as described in claim 5, characterized in that, Also includes: If it is determined that the current sub-region is not a candidate region, then the drone is controlled to fly to the next sub-region; The sub-region directly below the UAV is identified as the current sub-region, and the process returns to the steps of controlling the radar to transmit radar signals to the current sub-region and receiving the echo signals reflected by the radar signals from the current sub-region.

7. The method for determining the landing area of ​​a UAV as described in claim 5, characterized in that, The step of determining whether the current sub-region meets the preset landing conditions based on the depth values ​​of each object point and the first distance includes: Calculate the mean and variance of the depth values ​​for each object point within the sub-region; Determine the maximum and minimum depth values ​​for each object point within the sub-region; Calculate the difference between the mean and the first distance to obtain the first difference; When the first difference, variance, maximum value, and minimum value meet the preset landing conditions, it is determined that the sub-region meets the preset landing conditions. If the first difference, variance, maximum value and minimum value do not meet the preset landing conditions, the sub-region is determined to not meet the preset landing conditions. The preset landing condition is at least one of the following conditions: the first difference is less than a first preset difference threshold, the variance is less than a preset variance threshold, the maximum value is less than a preset maximum threshold, and the minimum value is greater than a preset minimum threshold.

8. The method for determining the landing area of ​​a UAV as described in claim 5, characterized in that, The radar data also includes a second distance from the UAV to the current sub-region, and the acquisition of radar data based on the radar signal and the echo signal includes: Based on the echo signal and the radar signal, a first distance and a second distance from the UAV to the current sub-region are determined, where the first distance and the second distance are the distances from the UAV to the first surface and the second surface of the current sub-region, respectively. The signal strength of the echo signal reflected from the first surface is obtained based on the echo signal and the radar signal.

9. The method for determining the landing area of ​​a UAV as described in claim 3, characterized in that, The radar data includes a first distance and a second distance from the UAV to a first surface and a second surface of the candidate region, respectively, as well as the signal strength of the echo signal from the first surface. Determining the landing area from the candidate region based on the radar data includes: Calculate the difference between the first distance and the second distance to obtain the second difference; Determine whether the second difference is greater than a second preset difference threshold; If so, then the candidate region is determined to be a non-landing region, meaning that the penetration thickness of the radar signal is less than the preset thickness. If not, determine that the candidate region is a region where the penetration thickness of the radar signal is less than a preset thickness, and determine whether the signal strength is less than a preset strength threshold. When the signal strength is greater than a preset strength threshold, the candidate region is determined to be a region where the signal strength of the reflected radar signal is greater than the preset threshold, and the candidate region is the landing region; When the signal strength is less than a preset strength threshold, the candidate region is determined to be a region where the signal strength of the reflected radar signal is greater than the preset threshold, and the candidate region is a non-landing region.

10. The method for determining the landing area of ​​a UAV as described in claim 9, characterized in that, Also includes: When it is determined that the candidate area is not a landing area, the UAV is controlled to fly to the next sub-area, and the process returns to the steps of controlling the radar to transmit radar signals to the current sub-area and receiving the echo signals reflected by the radar signals from the current sub-area.

11. A device for determining the landing area of ​​a drone, characterized in that, include: The operation boundary determination module is used to determine the operation boundary of the UAV when a forced landing event is detected. The operation boundary is the boundary of the operation area of ​​the UAV. A target boundary determination module is used to determine the target boundary from the operation boundary; The flight control module is used to control the UAV to fly along the target boundary; A landing area determination module is used to determine the landing area during the flight of the UAV along the target boundary; The target boundary determination module includes: The location information acquisition submodule is used to acquire the location information of the UAV; The first calculation submodule is used to calculate the distance from each operation boundary to the drone using the drone's location information; The first target boundary determination submodule is used to select the operation boundary with the smallest distance as the target boundary.

12. A drone, characterized in that, The drone includes: One or more processors; Storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the method for determining the drone landing area as described in any one of claims 1-10.

13. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by the processor, the program implements the method for determining the drone landing area as described in any one of claims 1-10.

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