A method, device, unmanned equipment and storage medium for imitating terrain flight

Abstract

The embodiment of the present invention discloses a method, device, unmanned equipment and storage medium for terrain-simulating flight. The method includes: when the unmanned equipment is in terrain-simulating flight, determining the actual flight height of the unmanned equipment; when the actual flight height is greater than the height threshold, controlling the unmanned equipment to perform terrain-simulating flight with a first strategy; when the actual flight height is less than or equal to the height threshold, controlling the unmanned equipment to perform terrain-simulating flight with a second strategy; the first strategy includes: determining the vertical speed of the unmanned equipment according to the first digital elevation model DEM information of the plot area where the unmanned equipment is currently located, controlling the unmanned equipment to perform terrain-simulating flight according to the vertical speed, and the plot area is determined according to the current flight position of the unmanned equipment. The embodiment of the present invention can realize the terrain-simulating flight of the unmanned equipment without being limited by the detection height of the terrain-simulating radar, and solves the technical problem in the prior art that the unmanned equipment cannot perform terrain-simulating flight when it cannot obtain ground height information from the terrain-simulating radar.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of terrain-imitating flight, and in particular to a terrain-imitating flight method, device, unmanned equipment, and storage medium. Background Art

[0002] Terrain-following flight refers to the process of unmanned equipment operating by setting a fixed height with the known three-dimensional terrain to maintain a constant height difference between the unmanned equipment and the three-dimensional terrain. Terrain-following flight can enable unmanned equipment to adapt to different terrains. At present, during the process of unmanned equipment performing terrain-following flight, the ground height information of the measured land is generally obtained through the terrain-following radar, and a variable altitude route is generated according to the ground height information to adjust its own altitude in real time, so as to maintain consistent ground resolution during the flight and improve the aerial survey effect.

[0003] However, due to the limited detection height of ground-following radar, when the unmanned equipment cannot obtain ground height information from the ground-following radar, the unmanned equipment can only fly level. While affecting the aerial survey effect, the unmanned equipment also has a high flight risk. Summary of the invention

[0004] The embodiments of the present invention provide a method and apparatus for terrain-imitating flight, an unmanned device, and a storage medium, which can realize the terrain-imitating flight of the unmanned device without being restricted by the detection height of a terrain-imitating radar, thereby solving the technical problem in the prior art that the unmanned device cannot perform terrain-imitating flight when it cannot obtain ground height information from the terrain-imitating radar.

[0005] In a first aspect, an embodiment of the present invention provides a method for terrain-imitating flight, comprising:

[0006] When the unmanned equipment is flying in the terrain simulation mode, determine the actual flight altitude of the unmanned equipment;

[0007] When the actual flight altitude is greater than the altitude threshold, the unmanned device is controlled to perform terrain-simulating flight using a first strategy; when the actual flight altitude is less than or equal to the altitude threshold, the unmanned device is controlled to perform terrain-simulating flight using a second strategy;

[0008] Wherein, the first strategy includes: determining the vertical speed of the unmanned device according to the first digital elevation model DEM information of the plot area where the unmanned device is currently located, and the plot area is determined according to the current flight position of the unmanned device;

[0009] The unmanned equipment is controlled to perform terrain-imitating flight according to the vertical speed.

[0010] Preferably, the first DEM information is sent to the unmanned device by the cloud server at a set frequency, the first DEM information is DEM information intercepted by the cloud server in the second DEM information according to the flight position, and the second DEM information is DEM information of the terrain-simulating flight area of ​​the unmanned device.

[0011] Preferably, the terrain-simulating flight area includes an operating area of ​​the unmanned equipment;

[0012] The method further comprises:

[0013] Controlling the unmanned equipment to vertically rise to a first set height at a take-off position;

[0014] The current real-time flight altitude is adjusted in real time during the process of the unmanned equipment flying from the take-off position to the operation starting position of the operation plot area, so that the real-time flight altitude of the unmanned equipment when it arrives at the operation starting position reaches the target flight altitude during the terrain simulation flight.

[0015] Preferably, the terrain-simulating flight area is a minimum plot area including a take-off position when the unmanned equipment starts flying and an operating plot area of ​​the unmanned equipment.

[0016] Preferably, before the unmanned device performs the terrain-simulating flight, the method further comprises:

[0017] A DEM information acquisition request is sent to the cloud server, so that the cloud server acquires the second DEM information of the terrain-imitation flight area according to the DEM information acquisition request and intercepts and sends the first DEM information from the second DEM information according to the set frequency after the unmanned device starts the terrain-imitation flight.

[0018] Preferably, the second strategy includes:

[0019] Determine the terrain-simulating flight altitude of the unmanned device according to first DEM information of the plot area where the unmanned device is currently located and surface altitude information measured by the radar of the unmanned device;

[0020] The unmanned equipment is controlled to perform terrain-imitating flight according to the terrain-imitating flight altitude.

[0021] Preferably, determining the vertical speed of the unmanned equipment according to the first DEM information of the plot area where the unmanned equipment is currently located includes:

[0022] Determining a feedforward control amount of the unmanned equipment according to first DEM information of a plot area where the unmanned equipment is currently located;

[0023] Determine a feedback control amount of the unmanned equipment according to the first DEM information and the actual flight altitude;

[0024] The vertical speed of the unmanned equipment is determined according to the feedforward control amount and the feedback control amount.

[0025] Preferably, determining the feedback control amount of the unmanned equipment according to the first DEM information and the flight altitude includes:

[0026] Determine the current target flight altitude of the unmanned equipment according to the first DEM information and the preset route altitude of the terrain simulation flight;

[0027] The target flight altitude and the actual flight altitude are input into a proportional control link, and the proportional control link is used to obtain a feedback control amount of the unmanned equipment.

[0028] Preferably, the land area corresponding to the first DEM information is a square land area centered on the current flight position of the unmanned equipment, and the square land area is divided into N×N square sub-areas, N≥3.

[0029] Preferably, determining the feedforward control amount of the unmanned equipment according to the first DEM information of the plot area where the unmanned equipment is currently located includes:

[0030] Determine the first-order differential component and the second-order differential component of the current target flight altitude of the unmanned equipment according to the first DEM information of the plot area where the unmanned equipment is currently located;

[0031] A feedforward control amount of the unmanned equipment is determined according to the first-order differential amount and the second-order differential amount.

[0032] Preferably, two adjacent sides in the square plot area are respectively in the east-west direction and the north-south direction;

[0033] Determining the first-order differential component and the second-order differential component of the current target flight altitude of the unmanned equipment according to the first DEM information of the plot area where the unmanned equipment is currently located includes:

[0034] Determine, according to the first DEM information of the plot area where the unmanned equipment is currently located, the first-order partial differential and the second-order partial differential of the current target flight altitude of the unmanned equipment in the due north direction of the flight location, the first-order partial differential and the second-order partial differential in the due east direction of the flight location, and the second-order partial differential in the due east direction from due north to due north of the flight location;

[0035] Determine the first-order differential of the target flight altitude according to the first-order partial differential in the due north direction and the first-order partial differential in the due east direction;

[0036] The second-order differential of the target flight altitude is determined based on the first-order partial differential and the second-order partial differential in the due north direction, the first-order partial differential and the second-order partial differential in the due east direction, and the second-order partial differential in the due north-to-due east direction.

[0037] Preferably, determining the first-order partial differential of the current target flight altitude of the unmanned equipment in the due north direction of the flight position according to the first DEM information of the plot area where the unmanned equipment is currently located includes:

[0038] Determine a first DEM height difference between a north square sub-area and a target square sub-area according to the first DEM information of the plot area where the unmanned equipment is currently located, wherein the target square sub-area is the square sub-area where the flight position is located, and the north square sub-area is the square sub-area located due north of the flight position and farthest from the flight position;

[0039] The first-order partial differential of the current target flight altitude of the unmanned equipment in the due north direction of the flight position is determined according to the first DEM height difference and the resolution of the square sub-area.

[0040] Preferably, determining the second-order partial differential of the current target flight altitude of the unmanned equipment in the due north direction of the flight position according to the first DEM information includes:

[0041] Determine a second DEM height difference between a target square sub-area and a southward square sub-area according to the first DEM information of the plot area where the unmanned equipment is currently located, wherein the southward square sub-area is a square sub-area located due south of the flight position and farthest from the flight position;

[0042] Subtract the second DEM height difference from the first DEM height difference to obtain a third DEM height difference;

[0043] The second-order partial differential of the current target flight altitude of the unmanned equipment in the due north direction of the flight position is determined according to the third DEM height difference and the resolution of the square sub-area.

[0044] Preferably, determining the second-order partial differential of the current target flight altitude of the unmanned equipment in the direction due north and due east of the flight position according to the first DEM information includes:

[0045] Determine, according to the first DEM information of the plot area where the unmanned equipment is currently located, a fourth DEM height difference between the northeastern square sub-area and the southeastern square sub-area, wherein the northeastern square sub-area is a square sub-area located northeast of the flight position and farthest from the flight position, and the southeastern square sub-area is a square sub-area located southeast of the flight position and farthest from the flight position;

[0046] Determine a fifth DEM height difference between a northwest square sub-area and a southwest square sub-area according to the first DEM information of the plot area where the unmanned equipment is currently located, wherein the northwest square sub-area is a square sub-area located northwest of the flight position and farthest from the flight position, and the southwest square sub-area is a square sub-area located southwest of the flight position and farthest from the flight position;

[0047] The second-order partial differential of the current target flight altitude of the unmanned equipment in the direction due north and due east of the flight position is determined according to the fourth DEM altitude difference, the fifth DEM altitude difference and the resolution of the square sub-area.

[0048] In a second aspect, an embodiment of the present invention provides a terrain-imitating flight device, including an altitude determination module and a flight strategy switching module;

[0049] The altitude determination module is used to determine the actual flight altitude of the unmanned device when the unmanned device is performing terrain imitation flight;

[0050] The flight strategy switching module is used to control the unmanned device to perform terrain-simulating flight with a first strategy when the actual flight altitude is greater than the altitude threshold; and to control the unmanned device to perform terrain-simulating flight with a second strategy when the actual flight altitude is less than or equal to the altitude threshold;

[0051] Among them, the first strategy includes: determining the vertical speed of the unmanned device according to the first digital elevation model DEM information of the plot area where the unmanned device is currently located, and controlling the unmanned device to perform terrain-simulating flight according to the vertical speed, and the plot area is determined according to the current flight position of the unmanned device.

[0052] In a third aspect, an embodiment of the present invention provides an unmanned device, the unmanned device comprising a processor and a memory;

[0053] The memory is used to store a computer program and transmit the computer program to the processor;

[0054] The processor is used to execute a terrain-simulating flight method as described in the first aspect according to instructions in the computer program.

[0055] In a fourth aspect, an embodiment of the present invention provides a storage medium storing computer executable instructions, wherein the computer executable instructions, when executed by a computer processor, are used to execute a terrain-simulating flight method as described in the first aspect.

[0056] As described above, in the embodiment of the present invention, when the actual flight altitude of the unmanned equipment is greater than the altitude threshold, the vertical speed of the unmanned equipment is calculated in real time according to the first DEM information of the plot area where the unmanned equipment is located, and the unmanned equipment is controlled to perform ground-imitating flight according to the vertical speed. Even if the flight altitude of the unmanned equipment exceeds the detection range of the radar, the unmanned equipment can be controlled to perform ground-imitating flight according to the first DEM information, and the unmanned equipment is no longer dependent on the ground-imitating radar to enable the unmanned equipment to perform ground-imitating flight, which solves the technical problem in the prior art that the unmanned equipment cannot perform ground-imitating flight when it cannot obtain ground altitude information from the ground-imitating radar. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 A flow chart of a terrain-imitating flight method provided by an embodiment of the present invention.

[0058] Figure 2 A schematic diagram of communication between a drone and a cloud server provided in an embodiment of the present invention.

[0059] Figure 3 A schematic diagram of a take-off position of a UAV and an operating area of ​​the UAV provided in an embodiment of the present invention.

[0060] Figure 4 A flow chart of an unmanned device before starting terrain-simulating flight is provided in an embodiment of the present invention.

[0061] Figure 5 A flowchart of another unmanned device starting terrain-simulating flight provided by an embodiment of the present invention.

[0062] Figure 6 A flowchart of another terrain-simulating flight method provided by an embodiment of the present invention.

[0063] Figure 7 A flowchart of another terrain-simulating flight method provided by an embodiment of the present invention.

[0064] Figure 8 A schematic diagram of the structure of a vertical speed planning module provided in an embodiment of the present invention.

[0065] Fig. 9 A schematic diagram of a square plot area provided in an embodiment of the present invention.

[0066] Fig.10 A schematic diagram of a square plot area of ​​an unmanned device during flight provided by an embodiment of the present invention.

[0067] Fig.11 A schematic diagram of calculating vertical speed provided by an embodiment of the present invention.

[0068] Fig.12 A schematic structural diagram of a terrain-imitating flying device provided in an embodiment of the present invention.

[0069] Fig.13 A schematic diagram of the structure of an unmanned device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0070] The following description and accompanying drawings fully illustrate the specific embodiments of the present application so that those skilled in the art can practice them. The examples represent possible variations only. Unless explicitly required, separate components and functions are optional, and the order of operation can vary. The parts and features of some embodiments may be included in or replace the parts and features of other embodiments. The scope of the embodiments of the present application includes the entire scope of the claims, and all available equivalents of the claims. In this article, each embodiment may be represented individually or generally by the term "invention", which is only for convenience, and if more than one invention is disclosed in fact, it is not intended to automatically limit the scope of the application to any single invention or inventive concept. In this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, without requiring or implying any actual relationship or order between these entities or operations. Moreover, the term "include", "comprise" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method or device including a series of elements includes not only those elements, but also other elements that are not explicitly listed. The various embodiments are described in a progressive manner herein, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other. As for the structures, products, etc. disclosed in the embodiments, since they correspond to the parts disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0071] like Figure 1 As shown, Figure 1 A flowchart of a method for imitating a terrain in flight provided by an embodiment of the present invention. The method for imitating a terrain in flight provided by an embodiment of the present invention can be executed by an unmanned device, which can be implemented by software and / or hardware. The unmanned device can be composed of two or more physical entities, or can be composed of one physical entity. In one embodiment, the unmanned device refers to an unmanned device that can fly, for example, the unmanned device can be a drone or other device, and the method for imitating a terrain in flight includes the following steps:

[0072] Step 101: When the unmanned device is performing terrain imitation flight, determine the actual flight altitude of the unmanned device.

[0073] Exemplarily, the unmanned device has a function of terrain-simulating flight. When the function is run, the unmanned device performs terrain-simulating flight. In this embodiment, when the unmanned device is performing terrain-simulating flight, the actual flight height of the unmanned device is determined, and the actual flight height refers to the current height of the unmanned device from the horizontal line. In one embodiment, the actual flight height of the unmanned device can also be determined according to a set frequency, wherein the frequency can be set according to actual needs. Exemplarily, considering the real-time nature of following the terrain-simulating height during terrain-simulating flight of the unmanned device, the frequency can be pre-set to 25hz, and the period is 1 / 25=0.04S, that is, the actual flight height of the unmanned device is determined every 0.04 seconds.

[0074] In this embodiment, the unmanned device is a drone as an example for explanation, and the processor on the drone executes the terrain imitation flight method. The drone has a terrain imitation flight mode, in which the drone runs the terrain imitation function. When the drone enters the terrain imitation flight mode, it performs terrain imitation flight, and during the terrain imitation flight, the current real-time actual flight altitude of the drone is determined according to a preset frequency. The actual flight altitude of the drone can be obtained in a variety of ways. For example, a barometer is provided on the drone, the barometer is connected to the processor, the barometer is used to detect the air pressure value of the current environment where the drone is located, and the processor obtains the air pressure value of the current environment from the barometer to calculate the current actual flight altitude of the drone; or, an RTK (Real-time kinematic) module is provided on the drone, the RTK module is connected to the processor, the RTK module is used to achieve centimeter-level positioning, and the processor can obtain the positioning data on the RTK module to calculate the current actual flight altitude of the drone; or, a radar is provided on the drone, the radar is connected to the processor, the radar is used to measure the surface height information, and the processor determines the actual flight altitude of the unmanned device by obtaining the surface height information measured by the terrain imitation radar.

[0075] Step 102: When the actual flight altitude is greater than the altitude threshold, the unmanned device is controlled to perform terrain-simulating flight using a first strategy; when the actual flight altitude is less than or equal to the altitude threshold, the unmanned device is controlled to perform terrain-simulating flight using a second strategy.

[0076] Among them, the first strategy includes: determining the vertical speed of the unmanned equipment according to the first digital elevation model DEM information of the plot area where the unmanned equipment is currently located, controlling the unmanned equipment to perform terrain-simulating flight according to the vertical speed, and the plot area is determined according to the current flight position of the unmanned equipment.

[0077] At present, in order to ensure that the unmanned equipment can perform terrain-simulating flight at all flight altitudes, different terrain-simulating flight strategies are set for different flight altitude ranges. After that, the appropriate terrain-simulating flight strategy can be selected based on the current actual flight altitude. During the execution process, after obtaining the actual flight altitude, the actual flight altitude is compared with the preset altitude threshold. The preset altitude can be set according to actual needs. The altitude threshold can be considered as the boundary altitude of the flight altitude range. When the actual flight altitude is greater than the altitude threshold, the first strategy is used for terrain-simulating flight; when the actual flight altitude is less than or equal to the altitude threshold, the second strategy is used for terrain-simulating flight. In this embodiment, considering the detection altitude of the radar on the unmanned equipment, the altitude threshold is set to 300 meters.

[0078] In one embodiment, when the actual flight altitude is greater than the altitude threshold, the first strategy is to calculate the vertical speed that the unmanned device needs to reach in the vertical direction based on the first digital elevation model (DEM) information of the current block area of ​​the unmanned device (hereinafter referred to as the first DEM information), and control the unmanned device to perform terrain-simulating flight according to the vertical speed. Among them, DEM is a discrete mathematical expression of the topography of the earth's surface. DEM information represents a finite sequence of three-dimensional vectors in a certain area, which is described in the form of a function:

[0079] V i =(X i ,Y i ,Z i ); i=1,2,...,n

[0080] Among them, X i , Y i is the plane coordinate, Z i is (X i , Y i ), in this embodiment, the DEM information currently used is recorded as the first DEM information, and the first DEM information is a mathematical expression of the surface topography of the plot area where the unmanned device is currently located, wherein the plot area where the unmanned device is currently located includes the ground area corresponding to the current flight position of the unmanned device and the ground area within a certain range around the flight position. Optionally, the plot area is a square area.

[0081] There is currently no limitation on the method for obtaining the first DEM information. For example, the first DEM information is obtained from a cloud server. At this time, the first DEM information is sent to the unmanned device by the cloud server at a set frequency. The first DEM information is DEM information intercepted by the cloud server in the second DEM information according to the flight position, and the second DEM information is DEM information of the terrain-simulating flight area of ​​the unmanned device.

[0082] In one embodiment, Figure 2 As shown, taking the unmanned device as a drone as an example, the unmanned device can also communicate with the cloud server, wherein the cloud server is a device that uses network technology to communicate with the unmanned device and provides services for the unmanned device. During the communication process, the processor of the unmanned device uses a communication module to communicate with the cloud server, wherein the communication standard used in the communication process is not currently limited. When the unmanned device starts to perform a terrain-simulating flight, the unmanned device uploads the route of the terrain-simulating flight to the cloud server. After receiving the route of the terrain-simulating flight, the cloud server confirms the area passed by the unmanned device during the terrain-simulating flight, that is, the terrain-simulating flight area. Afterwards, the DEM information of the terrain-simulating flight area passed by the unmanned device during the terrain-simulating flight is obtained. Currently, the DEM information of the terrain-simulating flight area is recorded as the second DEM information. For example, the cloud server can obtain the second DEM information of the terrain-simulating flight area from the open source DEM digital elevation model provided by Google.

[0083] Later, during the unmanned device's terrain-simulating flight process, the cloud server can obtain the unmanned device's current flight position at a set frequency, wherein the flight position can be determined by the unmanned device and uploaded to the cloud server at a set frequency, wherein the unmanned device can obtain the current flight position from the positioning system in real time and upload it to the cloud server. Optionally, the flight position can also be obtained by the cloud server in other ways, such as using a navigation system on the ground to determine the flight position. After the cloud server obtains the current flight position of the unmanned device, it determines the plot area where the unmanned device is currently located, and extracts the first DEM information of the plot area where the unmanned device is currently located from the second DEM information of the terrain-simulating flight area. Afterwards, the cloud server sends the first DEM information to the unmanned device. The cloud server sends the first DEM information to the unmanned device at a frequency for use by the unmanned device. In one embodiment, the frequency at which the cloud server sends the first DEM information to the unmanned device is consistent with the frequency at which the unmanned device determines the actual flight altitude, both of which are 25hz.

[0084] In practical applications, the cloud server may obtain the second DEM information and then send the second DEM information to the unmanned device. During the unmanned device's terrain-simulating flight, the unmanned device intercepts the first DEM information from the second DEM information in combination with its own flight position.

[0085] In one embodiment, when the unmanned device determines that the current actual flight altitude is greater than the altitude threshold, the vertical speed of the unmanned device in the vertical direction during flight is calculated according to the first DEM information sent by the cloud server. The vertical speed can change the current actual flight altitude.

[0086] It is understandable that the unmanned device stores a preset route height, which is the height that the unmanned device should maintain with the ground surface during terrain-simulating flight. The preset route height can be input into the unmanned device by the user before the unmanned device flies. Exemplarily, the unmanned device can determine the height of the ground surface of the current plot area through the first DEM information, and then determine the vertical speed during terrain-simulating flight according to the height of the ground surface and the preset route height. In an optional manner, the unmanned device determines the feedforward control amount and the feedback control amount according to the first DEM information, and determines the vertical speed according to the feedforward control amount and the feedback control amount. Among them, the feedback control amount is used to eliminate the error between the actual flight height of the unmanned device and the target flight height, wherein the target flight height is the sum of the surface height and the preset route height, that is, the flight height that the unmanned device should reach under the actual surface during terrain-simulating flight. It can be understood that the feedback control amount is determined when the actual flight altitude has been obtained. At this time, the regulatory effect of the feedback control amount will lag behind the interference caused by the error, showing hysteresis. Therefore, the feedforward control amount is used to reduce the hysteresis caused by the feedback control. For example, since the land area corresponding to the first DEM information contains the land area within a certain range of the current flight position of the unmanned equipment, the unmanned equipment can determine the surface height at the next flight time in combination with the elevation of the surrounding land parcels, and then determine the feedforward control amount required to compensate for the hysteresis. The feedback control amount and the feedforward control amount are both control amounts for the vertical speed. Afterwards, the vertical speed required for the unmanned equipment to meet the terrain simulation flight is determined based on the feedback control amount and the feedforward control amount.

[0087] After determining the vertical speed of the unmanned device in the vertical direction, the unmanned device controls the flight in the vertical direction according to the vertical speed. The vertical speed refers to the lifting speed of the unmanned device. Controlling the vertical speed of the unmanned device is actually controlling the longitudinal trajectory angle or heading trajectory angle of the unmanned device, so that the unmanned device climbs or descends. In this embodiment, the unmanned device controls the flight in the vertical direction according to the vertical speed so that the height between the unmanned device and the ground surface is fixed at a preset route height, that is, the unmanned device can adjust the flight altitude according to the ups and downs of the terrain, thereby completing the terrain-imitating flight.

[0088] In the embodiment of the present invention, when the actual flight altitude of the unmanned device is greater than the altitude threshold, the vertical speed of the unmanned device is calculated in real time according to the first DEM information of the plot area where the unmanned device is located, and the unmanned device is controlled to perform ground-following flight according to the vertical speed. Even when the flight altitude of the unmanned device exceeds the detection range of the radar, the first DEM information can be used to control the ground-following flight of the unmanned device, and the unmanned device is no longer dependent on the ground-following radar to perform ground-following flight, which solves the technical problem in the prior art that the unmanned device cannot perform ground-following flight when it cannot obtain ground altitude information from the ground-following radar. In particular, when performing aerial survey tasks based on the ground-following flight function, the unmanned device is allowed to shoot at a fixed height from the ground surface, so that the ground resolution in the captured image or video is consistent (that is, the actual area of ​​the ground in the image or video is consistent), ensuring the aerial survey effect, and preventing the problem of insufficient overlap in adjacent images due to terrain undulations (such as the edge ground in the previous frame image is not included in the current frame image).

[0089] In one embodiment, the terrain simulation flight area corresponding to the second DEM information includes the operating area of ​​the unmanned equipment; wherein the operating area refers to the area that the unmanned equipment needs to pass through when performing tasks such as aerial survey. For example, Figure 3 As shown, it shows the land area involved in a flight process of an unmanned device. The unmanned device takes off from the take-off position and flies to the operation starting position. After that, it starts to perform tasks (such as aerial survey tasks) from the operation starting position. The ground area involved in the task process is the operation plot area. At this time, the unmanned device performs a terrain simulation flight in the operation plot area, and the second DEM information obtained by the cloud server only corresponds to the operation plot area. At this time, Figure 4 A flowchart of an unmanned device before starting terrain-simulating flight is provided in an embodiment of the present invention, such as Figure 4 As shown, when the unmanned device is flying in a terrain-simulating manner, before determining the actual flight altitude of the unmanned device, the following steps are also included:

[0090] Step 1001: Control the unmanned equipment to vertically rise to a first set height at the take-off position.

[0091] In one embodiment, the first set altitude is a pre-set altitude, which can be an altitude set by the user when setting the route of the unmanned device and can be changed according to actual conditions, or a fixed altitude value. When the unmanned device receives a flight instruction sent by a remote controller controlling the unmanned device, the flight is started, and the unmanned device is controlled to rise vertically to the first set altitude at the take-off position. Optionally, when the unmanned device starts the flight, it is in the take-off position.

[0092] Step 1002: When the unmanned device is flying from the take-off position to the operation starting position of the operation area, the current real-time flight altitude is adjusted in real time, so that the real-time flight altitude of the unmanned device when it arrives at the operation starting position reaches the target flight altitude during the terrain simulation flight.

[0093] The operation starting point refers to the starting point of the unmanned equipment in the operation plot area, and the operation starting point can be set according to actual needs. After the unmanned equipment rises vertically to the first set height at the take-off position, it flies to the operation starting point of the operation plot area, and during the flight, it also adjusts the current real-time flight altitude in real time, so that when the unmanned equipment reaches the operation starting point of the operation plot area, the real-time flight altitude can reach the target flight altitude during the terrain-simulating flight. It can be understood that the target flight altitude refers to the flight altitude that the unmanned equipment needs to maintain during the terrain-simulating flight. In the embodiment, the unmanned equipment starts the terrain-simulating flight after reaching the target flight altitude. At this time, the target flight altitude is a pre-set altitude, and after the terrain-simulating flight, the unmanned equipment can update the target flight altitude according to the elevation of the plot area in the first DEM information, so that the unmanned equipment and the ground surface always maintain the set route altitude.

[0094] After the unmanned equipment reaches the operation starting point, it can perform terrain-simulating flight. During the terrain-simulating flight, when the actual flight altitude of the unmanned equipment is greater than the altitude threshold, the vertical speed of the unmanned equipment is calculated according to the first DEM information of the block area where the unmanned equipment is currently located, and the unmanned equipment is controlled to perform terrain-simulating flight according to the vertical speed.

[0095] In another embodiment, the terrain-simulating flight area corresponding to the second DEM information may also be the minimum plot area of ​​the take-off position when the unmanned equipment starts the flight and the operating plot area of ​​the unmanned equipment. Considering that the take-off point (i.e., the take-off position) of the unmanned equipment may be a certain distance away from the operating plot area, the unmanned equipment may encounter obstacles such as high ground or hillsides during the flight to the operating starting point, which is not conducive to the flight of the unmanned equipment. Therefore, the second DEM information obtained by the cloud server corresponds to the minimum plot area that includes both the take-off position when the unmanned equipment starts the flight and the operating plot area of ​​the unmanned equipment, that is, Figure 3 As shown in the outer box in the figure, the unmanned equipment can start terrain-simulating flight from the take-off position. Figure 5 Another flowchart of starting terrain-simulating flight of an unmanned device provided by an embodiment of the present invention is as follows: Figure 5 As shown, when the unmanned device is flying in a terrain-simulating manner, before determining the actual flight altitude of the unmanned device, the following steps are also included:

[0096] Step 1003: Start the flight and control the unmanned equipment to rise vertically to a second set height at the take-off position.

[0097] Among them, the second set altitude is a pre-set altitude, which can be a altitude set by the user when setting the route of the unmanned equipment and can be changed according to actual conditions, or it can be a fixed altitude value.

[0098] Step 1004: Start terrain-simulating flight.

[0099] After the unmanned device starts flying from the take-off position and controls the unmanned device to rise vertically to the second set height, the terrain-imitating flight can be started. During the terrain-imitating flight, when the actual flight height of the unmanned device is greater than the height threshold, the vertical speed of the unmanned device is calculated according to the first DEM information of the plot area where the unmanned device is currently located, and the unmanned device is controlled to perform terrain-imitating flight according to the vertical speed, so that the unmanned device can avoid obstacles even if it encounters terrain obstacles during the process of flying from the take-off position to the operation starting position of the operation plot area.

[0100] In one embodiment, the unmanned device may instruct the cloud server to obtain the corresponding second DEM information before starting the terrain imitation flight. In one embodiment, before the unmanned device starts the terrain imitation flight, the cloud server is instructed to obtain the second DEM information for example, at this time, it also includes: sending a DEM information acquisition request to the cloud server, so that the cloud server obtains the second DEM information of the terrain imitation flight area according to the DEM information acquisition request and intercepts and sends the first DEM information from the second DEM information according to the set frequency after the unmanned device starts the terrain imitation flight.

[0101] In one embodiment, the DEM information acquisition request is used to instruct the cloud server to acquire the second DEM information. Optionally, the DEM information acquisition request may include the route for the unmanned device to perform terrain-simulating flight or to perform a task, or may include the terrain-simulating flight area that the unmanned device needs to pass through during the terrain-simulating flight. In one embodiment, taking the DEM information acquisition request including the route for performing a task as an example, specifically, before the unmanned device starts the terrain-simulating flight, the DEM information acquisition request is sent to the cloud server. After the cloud server obtains the DEM information acquisition request, it determines the terrain-simulating flight area that the unmanned device needs to pass through during the terrain-simulating flight according to the route, and acquires the second DEM information of the terrain-simulating flight area. At this time, the cloud server determines the operating plot area according to the route and acquires the second DEM information, or the cloud server determines the second DEM information of the minimum plot area including the take-off position and the operating plot area according to the route and the take-off position of the unmanned device. Alternatively, the cloud server determines the terrain-simulating flight area and acquires the corresponding second DEM information according to whether the take-off position is included in the DEM information acquisition request. Later, during the unmanned device's terrain-simulating flight, the first DEM information is intercepted from the second DEM information at a set frequency, and the first DEM information is sent to the unmanned device.

[0102] As described above, the embodiment of the present invention can perform terrain-simulating flight only in the operation plot area, or can perform terrain-simulating flight at takeoff, making the terrain-simulating flight process more flexible. Moreover, performing terrain-simulating flight at takeoff can enable the unmanned device to avoid obstacles during the process of flying to the operation starting position of the operation plot area, ensuring the safety of the unmanned device during the process of flying to the operation plot and ensuring the normal operation. Moreover, the cloud server intercepts the first DEM information from the second DEM information and pushes it to the unmanned device, so that the unmanned device only processes the first DEM information with a smaller data volume, saving the cache space of the unmanned device.

[0103] Figure 6 The flowchart of another method for imitating terrain flight provided by an embodiment of the present invention is based on the above embodiment, and describes controlling the unmanned equipment to perform imitating terrain flight using a second strategy when the actual flight altitude is less than or equal to the altitude threshold. Figure 6 As shown, the following steps are included:

[0104] Step 201: When the unmanned device is performing terrain imitation flight, determine the actual flight altitude of the unmanned device.

[0105] Step 202: When the actual flight altitude is greater than the altitude threshold, the unmanned device is controlled to perform terrain-simulating flight using a first strategy; When the actual flight altitude is less than or equal to the altitude threshold, the unmanned device is controlled to perform terrain-simulating flight using a second strategy;

[0106] Among them, the first strategy includes: determining the vertical speed of the unmanned equipment according to the first digital elevation model DEM information of the plot area where the unmanned equipment is currently located, controlling the unmanned equipment to perform terrain-simulating flight according to the vertical speed, and the plot area is determined according to the current flight position of the unmanned equipment.

[0107] The second strategy includes:

[0108] Step 2021: Determine the terrain-simulating flight altitude of the unmanned device according to the first DEM information of the plot area where the unmanned device is currently located and the surface altitude information measured by the radar of the unmanned device.

[0109] When the actual flight altitude is less than or equal to the altitude threshold, the unmanned device performs ground-flight simulation using the second strategy. Specifically, the unmanned device determines the ground-flight simulation altitude of the unmanned device based on the first DEM information and the surface altitude information measured by the radar of the unmanned device, and controls the unmanned device to perform ground-flight simulation based on the ground-flight simulation altitude. Among them, the ground-flight simulation altitude refers to the flight altitude that the unmanned device needs to maintain when it is currently performing ground-flight simulation. It should be noted that the ground-flight simulation altitude and the target flight altitude have the same meaning, and the only difference is that one is the altitude calculated when the actual flight altitude is greater than the altitude threshold, and the other is the altitude calculated when the actual flight altitude is less than or equal to the altitude threshold. Specifically, after the unmanned device obtains the first DEM information, the current vertical speed of the unmanned device is calculated based on the first DEM information, and the vertical speed is integrated to calculate the first flight altitude, wherein the first flight altitude refers to the flight altitude of the unmanned device calculated using the first DEM information. At the same time, the unmanned equipment also determines a second flight altitude based on the surface altitude information obtained by radar detection, wherein the surface altitude information includes the altitude information of the unmanned equipment from the horizontal line of the ground surface corresponding to the current flight position. The second flight altitude refers to the flight altitude of the unmanned equipment calculated using the surface altitude information. The second flight altitude calculated using the surface altitude information has the advantages of high precision and high refresh rate.

[0110] After calculating the first flight altitude and the second flight altitude, the first flight altitude and the second flight altitude are fused to obtain the ground-simulating flight altitude. In one embodiment, the first flight altitude and the second flight altitude are fused using an extended Kalman filter. Specifically, during the fusion process, the Kalman state model in the extended Kalman filter can set the weight values ​​of the first flight altitude and the second flight altitude according to the refresh rates of the first flight altitude and the second flight altitude. The greater the refresh rate, the greater the weight value, so that during the fusion process, the high real-time characteristics of the first flight altitude and the advantages of the high refresh rate of the second flight altitude can be combined, thereby enhancing the ground-simulating flight effect of the unmanned equipment when the actual flight altitude is equal to or less than the altitude threshold.

[0111] Step 2022: Control the unmanned equipment to perform terrain-imitating flight according to the terrain-imitating flight altitude.

[0112] After obtaining the terrain-imitating flight altitude, the unmanned device can perform the terrain-imitating flight, and during the terrain-imitating flight, the actual flight altitude is controlled to be the terrain-imitating flight altitude.

[0113] In the embodiment of the present invention, when the actual flight altitude of the unmanned equipment is less than or equal to the altitude threshold, the first flight altitude calculated according to the first DEM information and the second flight altitude calculated according to the radar measurement result are integrated to obtain the terrain-simulating flight altitude, and the unmanned equipment is controlled to perform terrain-simulating flight according to the terrain-simulating flight altitude, so that the unmanned equipment can perform terrain-simulating flight at any flight altitude. By combining the high real-time characteristics of the first flight altitude with the high refresh rate characteristics of the second flight altitude, the terrain-simulating flight effect of the unmanned equipment is enhanced when the altitude is below the threshold.

[0114] Figure 7 The flowchart of another method for imitating terrain flight provided by an embodiment of the present invention is a detailed description of how to determine the vertical speed according to the first DEM information based on the above embodiment. Figure 7 As shown, the following steps are included:

[0115] Step 301: When the unmanned device is performing terrain-simulating flight, determine the actual flight altitude of the unmanned device.

[0116] Step 302: When the actual flight altitude is greater than the altitude threshold, the unmanned device is controlled to perform terrain-simulating flight using a first strategy; when the actual flight altitude is less than or equal to the altitude threshold, the unmanned device is controlled to perform terrain-simulating flight using a second strategy.

[0117] Among them, the first strategy includes:

[0118] Step 3021: determine the feedforward control amount of the unmanned device according to the first DEM information of the plot area where the unmanned device is currently located; the plot area is determined according to the current flight position of the unmanned device.

[0119] In this embodiment, the unmanned equipment is provided with a vertical speed planning module, and the vertical speed is calculated by the vertical speed planning module. The structure of the vertical speed planning module is as follows: Figure 8 As shown, it includes a control hysteresis module and a feedback control module. Among them, the control hysteresis module is used to calculate the feedforward control amount of the unmanned equipment according to the first DEM information. The feedforward control amount is used to improve the response ability of the unmanned equipment to the sudden change of the target flight altitude and eliminate the hysteresis caused by the feedback control amount. The target flight altitude refers to the flight altitude that the unmanned equipment needs to maintain during the terrain simulation flight. The target flight altitude = surface altitude + preset route altitude, wherein the preset route altitude is a fixed value preset by the user.

[0120] In one embodiment, the land area corresponding to the first DEM information is a square land area centered on the current flight position of the unmanned device, and the square land area is divided into N×N square sub-areas, where N≥3. At this time, the unmanned device is located in the square land area. In the first DEM information, each square sub-area corresponds to an elevation, for example, Fig. 9 As shown, taking N=3 as an example, the square plot area is composed of 9 square sub-areas. In the embodiment, hi is used to represent the elevation corresponding to the i-th square sub-area, 1≤i≤9, where h5 is the elevation of the current flight position of the unmanned device. It can be understood that in this embodiment, in order to ensure that the square sub-area where the unmanned device is located is located at the center of the square plot area, N needs to be set to an odd number, for example, N can also be set to 5 or 7.

[0121] In addition, considering the accuracy of the first DEM information, the resolution of each square sub-region is set to 30m×30m, that is, each square sub-region represents an area of ​​30m×30m on the ground surface.

[0122] Based on the above embodiment, step 3021 includes steps 30211-30212:

[0123] Step 30211: Determine the first-order differential and second-order differential of the current target flight altitude of the unmanned equipment based on the first DEM information of the plot area where the unmanned equipment is currently located.

[0124] First, the unmanned device calculates the first-order differential component and the second-order differential component of the current target flight altitude of the unmanned device according to the elevation of each square sub-area in the first DEM information.

[0125] In one embodiment, two adjacent sides in the square plot area are respectively in (or can be understood to be maintained in) the east-west direction and the north-south direction, that is, during the flight of the unmanned device, the direction of each side in the square plot area will not change according to the change of the flight direction of the unmanned device. For example, Fig.10 As shown, Fig.10 The black dots in the figure represent the square sub-areas where the drone is flying. Fig.10 The square plot area corresponding to the unmanned equipment at two flight times is shown. Fig.10 The arrow indicates the flight direction of the unmanned equipment ( Fig.10 The flight direction changes from due east to east-northeast), Fig.10 It can be seen that when the flight direction changes, the directions of the sides of the square area do not change.

[0126] Accordingly, step 30211 includes steps 302111 to 302113:

[0127] Step 302111, based on the first DEM information of the plot area where the unmanned equipment is currently located, determine the first-order partial differential and second-order partial differential of the current target flight altitude of the unmanned equipment in the north direction of the flight position, the first-order partial differential and second-order partial differential in the east direction of the flight position, and the second-order partial differential in the east direction from the north to the north of the flight position.

[0128] Based on the elevations represented by each square sub-area of ​​the first DEM information, the unmanned equipment calculates the first-order partial differential and second-order partial differential of the current target flight altitude of the unmanned equipment in the north direction of the flight position, the first-order partial differential and second-order partial differential in the east direction of the flight position, and the second-order partial differential in the east direction from the north to the flight position.

[0129] In one embodiment, determining the first-order partial differential of the current target flight altitude of the unmanned device in the due north direction of the flight position according to the first DEM information of the plot area where the unmanned device is currently located in step 30211 includes steps 3021111-3021112:

[0130] Step 3021111, determine the first DEM height difference between the north square sub-area and the target square sub-area based on the first DEM information of the plot area where the unmanned equipment is currently located, the target square sub-area is the square sub-area where the flight position is located, and the north square sub-area is the square sub-area located due north of the flight position and farthest from the flight position.

[0131] First, in the square plot area of ​​the first DEM information, determine the target square sub-area where the current flight position of the unmanned equipment is located, and determine the north-facing square sub-area located in the due north direction of the flight position and farthest from the flight position. Fig. 9 In the square plot area shown, the target square sub-area is the 5th square sub-area, and the north-facing square sub-area is the 8th square sub-area. The elevation h5 corresponding to the 5th square sub-area and the elevation h8 corresponding to the 8th square sub-area are obtained, and the first DEM height difference is obtained by subtracting h5 from h8.

[0132] Step 3021112: Determine the first-order partial differential of the current target flight altitude of the unmanned equipment in the north direction of the flight position based on the first DEM height difference and the resolution of the square sub-area.

[0133] Resolution can also be understood as the actual length represented by the side of the square sub-area. After obtaining the first DEM height difference, it is necessary to determine the distance between the center of the north-facing square sub-area and the center of the target square sub-area on the ground surface based on the resolution of the square sub-area. Then, the first DEM height difference is divided by the distance to obtain the first-order partial differential of the target flight altitude in the due north direction of the flight position. Fig. 9 For example, when the resolution of the square sub-area is 30m×30m, the length of the side of the square sub-area on the ground is 30m. Fig. 9 The distance between the center of the 8th square sub-area and the center of the 5th square sub-area on the ground surface. Since the center of the 8th square sub-area and the center of the 5th square sub-area are separated by the length of the side of a square sub-area, the distance between the center of the 8th square sub-area and the center of the 5th square sub-area on the ground surface is 30m. Dividing the first DEM height difference by 30m can obtain the first-order partial differential of the target flight altitude in the north direction of the flight position.

[0134] Similarly, when calculating the first-order partial differential in the due east direction of the flight position, the east-facing square sub-region located due east of the flight position and farthest from the flight position is determined. Fig. 9 In the square plot area shown, the eastward square sub-area is the sixth square sub-area. The elevation h6 corresponding to the sixth square sub-area is obtained, and the eastward DEM height difference is obtained by subtracting h5 from h6. Then, the eastward DEM height difference is divided by the distance between the center of the eastward square sub-area and the center of the target square sub-area on the surface, and the first-order partial differential of the target flight altitude in the east direction of the flight position can be obtained.

[0135] In one embodiment, determining the second-order partial differential of the current target flight altitude of the unmanned equipment in the due north direction of the flight position according to the first DEM information in step 302111 includes steps 3021113 to 3021115:

[0136] Step 3021113, determine the second DEM height difference between the target square sub-area and the south square sub-area based on the first DEM information of the plot area where the unmanned equipment is currently located, and the south square sub-area is the square sub-area located due south of the flight position and farthest from the flight position.

[0137] After calculating the first-order partial differential of the target flight altitude in the due north direction of the flight position, it is necessary to further calculate the second-order partial differential of the target flight altitude in the due north direction of the flight position. Specifically, in the square plot area of ​​the first DEM information, determine the south-facing square sub-area that is located in the due south direction of the flight position and is farthest from the flight position. For example, for example Fig. 9 In the square plot area shown, the south-facing square sub-area is the second square sub-area. The elevation h2 corresponding to the second square sub-area is obtained, and the second DEM height difference is obtained by subtracting h2 from h5.

[0138] Step 3021114: Subtract the second DEM height difference from the first DEM height difference to obtain a third DEM height difference.

[0139] Step 3021115: Determine the second-order partial differential of the current target flight altitude of the unmanned equipment in the north direction of the flight position based on the height difference of the third DEM and the resolution of the square sub-area.

[0140] In this embodiment, after obtaining the third DEM information, the distance between the center of the north-facing square sub-region and the center of the target square sub-region on the ground surface is determined according to the resolution of the square sub-region, and the third DEM information is divided by the square of the distance between the center of the north-facing square sub-region and the center of the target square sub-region on the ground surface to obtain the second-order partial differential of the target flight altitude in the due north direction of the flight position. For example, when Fig. 9 When the resolution of the middle square sub-area is 30m × 30m, the distance between the center of the 8th square sub-area and the center of the 5th square sub-area on the surface is 30m. Dividing the height difference of the third DEM by the square of 30m can obtain the second-order partial differential of the target flight altitude in the north direction of the flight position.

[0141] Similarly, when calculating the second-order partial differential in the east direction, in the square plot area of ​​the first DEM information, determine the west-facing square sub-area that is located in the west direction of the flight position and is farthest from the flight position, calculate the west-facing DEM height difference between the west-facing square sub-area and the target square sub-area, and calculate the second-order partial differential in the east direction based on the west-facing DEM height difference. For example, for example Fig. 9 In the square plot area shown, the west-facing square sub-area is the 4th square sub-area. Obtain the elevation h4 corresponding to the 4th square sub-area, and subtract h4 from h5 to obtain the west-facing DEM height difference. Then, subtract the east-facing DEM height difference from the west-facing DEM height difference to obtain the east-west height difference. Divide the east-west height difference by the square of the distance between the center of the 6th square sub-area and the center of the 5th square sub-area on the surface to obtain the second-order partial differential of the target flight altitude in the east direction of the flight position.

[0142] In one embodiment, determining the second-order partial differential of the current target flight altitude of the unmanned equipment in the direction of due north and due east of the flight position according to the first DEM information in step 302111 includes steps 3021116 to 3021118:

[0143] Step 3021116, determine the fourth DEM height difference between the northeast square sub-area and the southeast square sub-area based on the first DEM information of the plot area where the unmanned equipment is currently located, the northeast square sub-area is the square sub-area located northeast of the flight position and farthest from the flight position, and the southeast square sub-area is the square sub-area located southeast of the flight position and farthest from the flight position.

[0144] For example, in the square plot area of ​​the first DEM information, a northeast-oriented square sub-area located northeast of the flight position and farthest from the flight position is determined, and a southeast-oriented square sub-area located southeast of the flight position and farthest from the flight position is determined. Then, the elevation of the northeast-oriented square sub-area and the elevation of the southeast-oriented square sub-area are obtained from the first DEM information, and the difference between the two elevations is calculated to obtain the fourth DEM height difference. For example, for example Fig. 9 In the square plot area shown, the northeast square sub-area is the 9th square sub-area, and the elevation h9 corresponding to the 9th square sub-area is obtained. The southeast square sub-area is the 3rd square sub-area, and the elevation h3 corresponding to the 3rd square sub-area is obtained. The fourth DEM height difference is obtained by subtracting h3 from h9.

[0145] Step 3021117, determine the fifth DEM height difference between the northwest square sub-area and the southwest square sub-area based on the first DEM information of the plot area where the unmanned equipment is currently located, the northwest square sub-area is the square sub-area located northwest of the flight position and farthest from the flight position, and the southwest square sub-area is the square sub-area located southwest of the flight position and farthest from the flight position.

[0146] Then, in the square plot area of ​​the first DEM information, a northwest-facing square sub-area located northwest of the flight position and farthest from the flight position is determined, and a southwest-facing square sub-area located southwest of the flight position and farthest from the flight position is determined. Then, the elevation of the northwest-facing square sub-area and the elevation of the southwest-facing square sub-area are obtained from the first DEM information, and the difference between the two elevations is calculated to obtain the fifth DEM height difference. For example, for example, Fig. 9 In the square plot area shown, the northwest square sub-area is the 7th square sub-area, and the elevation h7 corresponding to the 7th square sub-area is obtained. The southwest square sub-area is the 1st square sub-area, and the elevation h1 corresponding to the 1st square sub-area is obtained. The fifth DEM height difference is obtained by subtracting h7 from h1.

[0147] Step 3021118: Determine the second-order partial differential of the current target flight altitude of the unmanned equipment in the direction of due north and due east of the flight position based on the fourth DEM height difference, the fifth DEM height difference and the resolution of the square sub-area.

[0148] In one embodiment, the fourth DEM height difference is first subtracted from the fifth DEM height difference to obtain the sixth DEM height difference, and then the distance between the center of the east-facing square sub-area and the center of the west-facing square sub-area on the ground surface is calculated according to the resolution of the square sub-area, and the sixth DEM height difference is divided by the distance between the center of the east-facing square sub-area and the center of the west-facing square sub-area on the ground surface to obtain the second-order partial differential of the target flight altitude in the direction of due north by due east of the flight position. For example, Fig. 9 When the resolution of the square sub-area is 30m×30m, the distance between the center of the 6th square sub-area and the center of the 4th square sub-area on the surface is 60m. Dividing the height difference of the sixth DEM by 60m, the second-order partial differential of the target flight altitude in the direction of due north and due east of the flight position can be obtained.

[0149] It can be understood that the order of determining the fourth DEM height difference and the fifth DEM height difference is not currently limited.

[0150] Step 302112: Determine the first-order differential of the target flight altitude based on the first-order partial differential in the due north direction and the first-order partial differential in the due east direction.

[0151] After calculating the first-order partial differential in the due north direction and the first-order partial differential in the due east direction, the first-order partial differential of the target flight altitude can be obtained according to the first-order partial differential in the due north direction and the first-order partial differential in the due east direction. Specifically, as shown in formula (1):

[0152]

[0153] in, Represents the first-order differential of the target flight altitude, Indicates the northbound speed of the unmanned equipment. Indicates the eastward speed of the unmanned equipment, represents the first-order partial differential in the north direction, It represents the first-order partial differential in the east direction, and the northward velocity and the eastward velocity can be directly measured.

[0154] Step 302113, determine the second-order differential of the target flight altitude based on the first-order partial differential and the second-order partial differential in the due north direction, the first-order partial differential and the second-order partial differential in the due east direction, and the second-order partial differential in the direction of due north and due east.

[0155] Finally, the second-order differential of the target flight altitude can be calculated based on the first-order partial differential and the second-order partial differential in the due north direction, the first-order partial differential and the second-order partial differential in the due east direction, and the second-order partial differential in the due north-due east direction. Specifically, in one embodiment, the calculation process of the second-order differential is shown in formula (2):

[0156]

[0157] in, is the second-order differential, is the northward acceleration of the unmanned equipment, is the eastward acceleration of the unmanned equipment, is the second-order partial differential in the north direction, is the second-order partial differential in the due east direction, Represents the second partial differential in the direction of due north and due east. The north acceleration and east acceleration can be determined based on the north velocity and east velocity respectively.

[0158] Step 30212: Determine the feedforward control amount of the unmanned equipment based on the first-order differential and the second-order differential.

[0159] In one embodiment, the calculation process of the feedforward control amount is shown in formula (3):

[0160]

[0161] Among them, V ff is the feedforward control quantity, a is the delay coefficient of the control lag module, which can be obtained by later debugging. Substituting the first-order differential and the second-order differential into formula (3) can obtain the feedforward control quantity.

[0162] Step 3022: Determine the feedback control amount of the unmanned equipment according to the first DEM information and the actual flight altitude.

[0163] While calculating the feedforward control amount, the feedback control amount of the unmanned equipment is also calculated according to the first DEM information and the actual flight altitude. The feedback control amount is used to eliminate the error between the target flight altitude and the actual flight altitude of the unmanned equipment, so that the unmanned equipment can stably maintain the target flight altitude. In one embodiment, a proportional control link (also understood as a proportional controller) is provided in the feedback control module in the vertical speed planning module, and the feedback control amount is calculated by the proportional control link in the feedback control module.

[0164] Based on the above embodiment, step 3022 includes steps 30221-30222:

[0165] Step 30221: Determine the current target flight altitude of the unmanned equipment according to the first DEM information and the preset route altitude of the terrain simulation flight.

[0166] Exemplarily, the surface altitude of the current location of the unmanned device is determined based on the first DEM information, and the surface altitude is added to the preset route altitude pre-set by the user to obtain the current target flight altitude of the unmanned device.

[0167] Step 30222: input the target flight altitude and the actual flight altitude into the proportional control link, and use the proportional control link to obtain the feedback control amount of the unmanned equipment.

[0168] In one embodiment, the calculation formula of the feedback control amount in the proportional control link is shown in formula (4):

[0169] V fb =K p ·(Z act -Z ref ) (4)

[0170] Among them, V fb is the feedback control quantity, K p Represents the proportional control coefficient, Z act Indicates the actual flight altitude, Z refIndicates the target flight altitude. When the difference between the actual flight altitude and the target flight altitude approaches zero, the feedback control amount approaches zero, so that the unmanned equipment can stably follow the target flight altitude.

[0171] Step 3023: Determine the vertical speed of the unmanned equipment based on the feedforward control amount and the feedback control amount.

[0172] Exemplarily, by adding the feedforward control amount and the feedback control amount, the vertical speed of the unmanned equipment can be obtained.

[0173] For ease of understanding, the overall process of calculating vertical velocity is as follows Fig.11 As shown, the first DEM information is input into the control lag module to obtain a feedforward control amount, the target flight altitude is obtained according to the first DEM information, the target flight altitude and the actual flight altitude are input into the feedback module to obtain a feedback control amount, and then the vertical speed is obtained based on the feedforward control amount and the feedback control amount.

[0174] Step 3024: Control the unmanned equipment to perform terrain-simulating flight according to the vertical speed.

[0175] In the embodiment of the present invention, when the actual flight altitude of the unmanned equipment is greater than the altitude threshold, the feedforward control amount and the feedback control amount of the unmanned equipment are calculated in real time according to the first DEM information of the plot area where the unmanned equipment is located, and finally the vertical speed of the unmanned equipment is calculated according to the feedforward control amount and the feedback control amount, and the unmanned equipment is controlled to perform ground-simulating flight according to the vertical speed. In the embodiment of the present invention, even if the flight altitude of the unmanned equipment exceeds the detection range of the radar, the unmanned equipment can calculate the vertical speed and perform ground-simulating flight, which solves the technical problem in the prior art that the unmanned equipment cannot perform ground-simulating flight when it cannot obtain ground altitude information from the ground-simulating radar. In addition, the vertical speed calculation method in the embodiment of the present invention is simple, and the vertical speed has a high accuracy, which can enable the unmanned equipment to accurately follow the target flight altitude.

[0176] like Fig.12 As shown, Fig.12 A terrain-imitating flying device provided in an embodiment of the present invention includes an altitude determination module 401 and a flight strategy switching module 402;

[0177] The altitude determination module 401 is used to determine the actual flight altitude of the unmanned device when the unmanned device is performing terrain imitation flight;

[0178] The flight strategy switching module 402 is used to control the unmanned device to perform terrain-simulating flight with a first strategy when the actual flight altitude is greater than the altitude threshold; and to control the unmanned device to perform terrain-simulating flight with a second strategy when the actual flight altitude is less than or equal to the altitude threshold;

[0179] Among them, the first strategy includes: determining the vertical speed of the unmanned equipment according to the first digital elevation model DEM information of the plot area where the unmanned equipment is currently located, controlling the unmanned equipment to perform terrain-simulating flight according to the vertical speed, and the plot area is determined according to the current flight position of the unmanned equipment.

[0180] Based on the above embodiment, the first DEM information is sent to the unmanned device by the cloud server at a set frequency. The first DEM information is the DEM information intercepted by the cloud server in the second DEM information according to the flight position, and the second DEM information is the DEM information of the terrain-simulating flight area of ​​the unmanned device.

[0181] Based on the above embodiment, the terrain-simulating flight area includes the operation plot area of ​​the unmanned equipment;

[0182] The terrain-imitating flight device also includes a first flight control module, which is used to control the unmanned equipment to rise vertically to a first set height at a take-off position; in the process of the unmanned equipment flying from the take-off position to the operation starting position of the operation area, the current real-time flight altitude is adjusted in real time so that the real-time flight altitude of the unmanned equipment when it arrives at the operation starting position reaches the target flight altitude during the terrain-imitating flight.

[0183] Based on the above embodiment, the terrain-simulating flight area is the smallest plot area including the take-off position when the unmanned equipment starts flying and the operating plot area of ​​the unmanned equipment.

[0184] On the basis of the above embodiment, it also includes a request sending module, which is used to send a DEM information acquisition request to the cloud server before the unmanned device starts the terrain imitation flight, so that the cloud server obtains the second DEM information of the terrain imitation flight area according to the DEM information acquisition request and intercepts and sends the first DEM information from the second DEM information according to the set frequency after the unmanned device starts the terrain imitation flight.

[0185] Based on the above embodiment, the second strategy includes: determining the terrain-simulating flight altitude of the unmanned device according to the first DEM information of the current location of the unmanned device and the surface height information measured by the radar of the unmanned device; and controlling the unmanned device to perform terrain-simulating flight according to the terrain-simulating flight altitude.

[0186] Based on the above embodiment, the flight strategy switching module 402 is used to determine the vertical speed of the unmanned device according to the first DEM information of the block area where the unmanned device is currently located, including:

[0187] Used to determine the feedforward control amount of the unmanned equipment according to the first DEM information of the current plot area of ​​the unmanned equipment; determine the feedback control amount of the unmanned equipment according to the first DEM information and the actual flight altitude; determine the vertical speed of the unmanned equipment according to the feedforward control amount and the feedback control amount.

[0188] Based on the above embodiment, the flight strategy switching module 402 is used to determine the feedback control amount of the unmanned equipment according to the first DEM information and the flight altitude, including:

[0189] It is used to determine the current target flight altitude of the unmanned equipment according to the first DEM information and the preset route altitude of the terrain simulation flight; input the target flight altitude and the actual flight altitude into the proportional control link, and use the proportional control link to obtain the feedback control amount of the unmanned equipment.

[0190] On the basis of the above embodiment, the land area corresponding to the first DEM information is a square land area centered on the current flight position of the unmanned equipment, and the square land area is divided into N×N square sub-areas, where N≥3.

[0191] Based on the above embodiment, the flight strategy switching module 402 is used to determine the feedforward control amount of the unmanned device according to the first DEM information of the block area where the unmanned device is currently located, including:

[0192] It is used to determine the first-order differential and second-order differential of the current target flight altitude of the unmanned equipment according to the first DEM information of the plot area where the unmanned equipment is currently located; and determine the feedforward control amount of the unmanned equipment according to the first-order differential and the second-order differential.

[0193] Based on the above embodiment, two adjacent sides in the square plot area are respectively in the east-west direction and the north-south direction;

[0194] The flight strategy switching module 402 is used to determine the first-order differential component and the second-order differential component of the current target flight altitude of the unmanned device according to the first DEM information of the block area where the unmanned device is currently located, including:

[0195] Used to determine the first-order partial differential and second-order partial differential of the current target flight altitude of the unmanned equipment in the north direction of the flight position, the first-order partial differential and second-order partial differential in the east direction of the flight position, and the second-order partial differential in the east direction of the flight position according to the first DEM information of the plot area where the unmanned equipment is currently located; determine the first-order differential of the target flight altitude according to the first-order partial differential in the north direction and the first-order partial differential in the east direction; determine the second-order differential of the target flight altitude according to the first-order partial differential and second-order partial differential in the north direction, the first-order partial differential and second-order partial differential in the east direction, and the second-order partial differential in the east direction of the north.

[0196] Based on the above embodiment, the flight strategy switching module 402 is used to determine the first-order partial differential of the current target flight altitude of the unmanned equipment in the due north direction of the flight position according to the first DEM information of the plot area where the unmanned equipment is currently located, including:

[0197] It is used to determine the first DEM height difference between the north square sub-area and the target square sub-area according to the first DEM information of the plot area where the unmanned equipment is currently located, the target square sub-area is the square sub-area where the flight position is located, and the north square sub-area is the square sub-area located due north of the flight position and farthest from the flight position; according to the first DEM height difference and the resolution of the square sub-area, the first-order partial differential of the current target flight altitude of the unmanned equipment in the due north direction of the flight position is determined.

[0198] Based on the above embodiment, the flight strategy switching module 402 is used to determine the second-order partial differential of the current target flight altitude of the unmanned equipment in the due north direction of the flight position according to the first DEM information, including:

[0199] It is used to determine the second DEM height difference between the target square sub-area and the south square sub-area based on the first DEM information of the plot area where the unmanned equipment is currently located, where the south square sub-area is the square sub-area located due south of the flight position and farthest from the flight position; subtract the second DEM height difference from the first DEM height difference to obtain the third DEM height difference; determine the second-order partial differential of the current target flight altitude of the unmanned equipment in the due north direction of the flight position based on the third DEM height difference and the resolution of the square sub-area.

[0200] Based on the above embodiment, the flight strategy switching module 402 is used to determine the second-order partial differential of the current target flight altitude of the unmanned equipment in the direction of due north and due east of the flight position according to the first DEM information, including:

[0201] Used to determine the fourth DEM height difference between the northeast square sub-area and the southeast square sub-area according to the first DEM information of the plot area where the unmanned equipment is currently located, the northeast square sub-area is the square sub-area located northeast of the flight position and the farthest from the flight position, and the southeast square sub-area is the square sub-area located southeast of the flight position and the farthest from the flight position; determine the fifth DEM height difference between the northwest square sub-area and the southwest square sub-area according to the first DEM information of the plot area where the unmanned equipment is currently located, the northwest square sub-area is the square sub-area located northwest of the flight position and the farthest from the flight position, and the southwest square sub-area is the square sub-area located southwest of the flight position and the farthest from the flight position; determine the second-order partial differential of the current target flight altitude of the unmanned equipment in the direction of due north and due east of the flight position according to the fourth DEM height difference, the fifth DEM height difference and the resolution of the square sub-areas.

[0202] This embodiment also provides an unmanned device, such as Fig.13 As shown, the unmanned device 50 includes a processor 500 and a memory 501;

[0203] The memory 501 is used to store a computer program 502 and transmit the computer program 502 to the processor;

[0204] The processor 500 is used to execute the steps in the above-mentioned embodiment of the terrain simulation flight method according to the instructions in the computer program 502.

[0205] Exemplarily, the computer program 502 may be divided into one or more modules / units, which are stored in the memory 501 and executed by the processor 500 to complete the present application. The one or more modules / units may be a series of computer program instruction segments capable of completing specific functions, which are used to describe the execution process of the computer program 502 in the unmanned device 50.

[0206] The unmanned device 50 may include, but is not limited to, a processor 500 and a memory 501. Those skilled in the art will appreciate that Fig.13 It is only an example of the unmanned device 50 and does not constitute a limitation of the unmanned device 50. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the unmanned device 50 may also include input and output devices, network access devices, buses, etc.

[0207] The processor 500 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0208] The memory 501 may be an internal storage unit of the unmanned device 50, such as a hard disk or memory of the unmanned device 50. The memory 501 may also be an external storage device of the unmanned device 50, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the unmanned device 50. Further, the memory 501 may also include both an internal storage unit and an external storage device of the unmanned device 50. The memory 501 is used to store the computer program and other programs and data required by the unmanned device 50. The memory 501 may also be used to temporarily store data that has been output or is to be output.

[0209] The unmanned equipment 50 may also include a radar for detecting body surface height information, a communication module for communicating with a cloud server, and a barometer or RTK module for measuring actual flight altitude.

[0210] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described systems, systems and units can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0211] In the several embodiments provided in the present application, it should be understood that the disclosed systems, systems and methods can be implemented in other ways. For example, the system embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of systems or units, which can be electrical, mechanical or other forms.

[0212] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0213] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0214] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store computer programs.

[0215] An embodiment of the present invention further provides a storage medium containing computer executable instructions, wherein the computer executable instructions are used to execute a terrain imitation flight method when executed by a computer processor, the method comprising the following steps:

[0216] When the unmanned equipment is flying in the terrain simulation mode, determine the actual flight altitude of the unmanned equipment;

[0217] When the actual flight altitude is greater than the altitude threshold, the unmanned device is controlled to perform terrain-simulating flight using a first strategy; when the actual flight altitude is less than or equal to the altitude threshold, the unmanned device is controlled to perform terrain-simulating flight using a second strategy;

[0218] Among them, the first strategy includes: determining the vertical speed of the unmanned device according to the first digital elevation model DEM information of the plot area where the unmanned device is currently located, and controlling the unmanned device to perform terrain-simulating flight according to the vertical speed, and the plot area is determined according to the current flight position of the unmanned device.

[0219] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the embodiments of the present invention are not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the embodiments of the present invention. Therefore, although the embodiments of the present invention are described in more detail through the above embodiments, the embodiments of the present invention are not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the embodiments of the present invention, and the scope of the embodiments of the present invention is determined by the scope of the appended claims.

Claims

1. A method for imitating terrain flight, characterized in that: include: When the unmanned equipment is flying in the terrain simulation mode, determine the actual flight altitude of the unmanned equipment; When the actual flight altitude is greater than the altitude threshold, the unmanned device is controlled to perform terrain-simulating flight using a first strategy; when the actual flight altitude is less than or equal to the altitude threshold, the unmanned device is controlled to perform terrain-simulating flight using a second strategy; The first strategy includes: determining the vertical speed of the unmanned device according to the first DEM information of the plot area where the unmanned device is currently located, and controlling the unmanned device to perform terrain-simulating flight according to the vertical speed, wherein the plot area is determined according to the current flight position of the unmanned device; Wherein, determining the vertical speed of the unmanned device according to the first DEM information of the plot area where the unmanned device is currently located includes: Determining a feedforward control amount of the unmanned equipment according to first DEM information of a plot area where the unmanned equipment is currently located; Determine a feedback control amount of the unmanned equipment according to the first DEM information and the actual flight altitude; The vertical speed of the unmanned equipment is determined according to the feedforward control amount and the feedback control amount.

2. A method for imitating terrain flight according to claim 1, characterized in that: The first DEM information is sent to the unmanned device by the cloud server at a set frequency. The first DEM information is DEM information intercepted by the cloud server in the second DEM information according to the flight position. The second DEM information is DEM information of the terrain-simulating flight area of ​​the unmanned device.

3. A method for imitating terrain flight according to claim 2, characterized in that: The terrain-simulating flight area includes the operation area of ​​the unmanned equipment; The method further comprises: Controlling the unmanned equipment to vertically rise to a first set height at a take-off position; The current real-time flight altitude is adjusted in real time during the process of the unmanned equipment flying from the take-off position to the operation starting position of the operation plot area, so that the real-time flight altitude of the unmanned equipment when it arrives at the operation starting position reaches the target flight altitude during the terrain simulation flight.

4. A method for imitating terrain according to claim 2, characterized in that: The terrain-simulating flight area is the smallest plot area including the take-off position when the unmanned equipment starts flying and the operating plot area of ​​the unmanned equipment.

5. A method for imitating terrain flight according to claim 2, characterized in that: Before the unmanned device simulates the terrain, the method further includes: A DEM information acquisition request is sent to the cloud server, so that the cloud server acquires the second DEM information of the terrain-imitation flight area according to the DEM information acquisition request and intercepts and sends the first DEM information from the second DEM information according to the set frequency after the unmanned device starts the terrain-imitation flight.

6. A method for imitating terrain flight according to claim 1, characterized in that: The second strategy includes: Determine the terrain-simulating flight altitude of the unmanned device according to first DEM information of the plot area where the unmanned device is currently located and surface altitude information measured by the radar of the unmanned device; The unmanned equipment is controlled to perform terrain-imitating flight according to the terrain-imitating flight altitude.

7. A method for imitating terrain flight according to claim 1, characterized in that: The step of determining the feedback control amount of the unmanned equipment according to the first DEM information and the flight altitude includes: Determine the current target flight altitude of the unmanned equipment according to the first DEM information and the preset route altitude of the terrain simulation flight; The target flight altitude and the actual flight altitude are input into a proportional control link, and the proportional control link is used to obtain a feedback control amount of the unmanned equipment.

8. A method for imitating terrain flight according to claim 1, characterized in that: The land area corresponding to the first DEM information is a square land area centered on the current flight position of the unmanned equipment, and the square land area is divided into N×N square sub-areas, where N≥3.

9. A method for imitating terrain flight according to claim 8, characterized in that: The step of determining the feedforward control amount of the unmanned equipment according to the first DEM information of the plot area where the unmanned equipment is currently located comprises: Determine the first-order differential component and the second-order differential component of the current target flight altitude of the unmanned equipment according to the first DEM information of the plot area where the unmanned equipment is currently located; A feedforward control amount of the unmanned equipment is determined according to the first-order differential amount and the second-order differential amount.

10. A method for imitating terrain flight according to claim 9, characterized in that: Two adjacent sides in the square plot area are respectively in the east-west direction and the north-south direction; Determining the first-order differential component and the second-order differential component of the current target flight altitude of the unmanned equipment according to the first DEM information of the plot area where the unmanned equipment is currently located includes: Determine, according to the first DEM information of the plot area where the unmanned equipment is currently located, the first-order partial differential and the second-order partial differential of the current target flight altitude of the unmanned equipment in the due north direction of the flight location, the first-order partial differential and the second-order partial differential in the due east direction of the flight location, and the second-order partial differential in the due east direction from due north to due north of the flight location; Determine the first-order differential of the target flight altitude according to the first-order partial differential in the due north direction and the first-order partial differential in the due east direction; The second-order differential of the target flight altitude is determined based on the first-order partial differential and the second-order partial differential in the due north direction, the first-order partial differential and the second-order partial differential in the due east direction, and the second-order partial differential in the due north-to-due east direction.

11. A method for imitating terrain flight according to claim 10, characterized in that: Determining the first-order partial differential of the current target flight altitude of the unmanned equipment in the due north direction of the flight position according to the first DEM information of the plot area where the unmanned equipment is currently located includes: Determine a first DEM height difference between a north square sub-area and a target square sub-area according to the first DEM information of the plot area where the unmanned equipment is currently located, wherein the target square sub-area is the square sub-area where the flight position is located, and the north square sub-area is the square sub-area located due north of the flight position and farthest from the flight position; The first-order partial differential of the current target flight altitude of the unmanned equipment in the due north direction of the flight position is determined according to the first DEM height difference and the resolution of the square sub-area.

12. A method for imitating terrain flight according to claim 11, characterized in that: Determining the second-order partial differential of the current target flight altitude of the unmanned equipment in the due north direction of the flight position according to the first DEM information includes: Determine a second DEM height difference between a target square sub-area and a southward square sub-area according to the first DEM information of the plot area where the unmanned equipment is currently located, wherein the southward square sub-area is a square sub-area located due south of the flight position and farthest from the flight position; Subtract the second DEM height difference from the first DEM height difference to obtain a third DEM height difference; The second-order partial differential of the current target flight altitude of the unmanned equipment in the due north direction of the flight position is determined according to the third DEM height difference and the resolution of the square sub-area.

13. A method for imitating terrain flight according to claim 10, characterized in that: Determining the second-order partial differential of the current target flight altitude of the unmanned equipment in the direction due north and due east of the flight position according to the first DEM information includes: Determine, according to the first DEM information of the plot area where the unmanned equipment is currently located, a fourth DEM height difference between the northeastern square sub-area and the southeastern square sub-area, wherein the northeastern square sub-area is a square sub-area located northeast of the flight position and farthest from the flight position, and the southeastern square sub-area is a square sub-area located southeast of the flight position and farthest from the flight position; Determine a fifth DEM height difference between a northwest square sub-area and a southwest square sub-area according to the first DEM information of the plot area where the unmanned equipment is currently located, wherein the northwest square sub-area is a square sub-area located northwest of the flight position and farthest from the flight position, and the southwest square sub-area is a square sub-area located southwest of the flight position and farthest from the flight position; The second-order partial differential of the current target flight altitude of the unmanned equipment in the direction due north and due east of the flight position is determined according to the fourth DEM altitude difference, the fifth DEM altitude difference and the resolution of the square sub-area.

14. A ground-imitation flying device, characterized in that: Including altitude determination module and flight strategy switching module; The altitude determination module is used to determine the actual flight altitude of the unmanned device when the unmanned device is performing terrain imitation flight; The flight strategy switching module is used to control the unmanned device to perform terrain-simulating flight with a first strategy when the actual flight altitude is greater than the altitude threshold; and to control the unmanned device to perform terrain-simulating flight with a second strategy when the actual flight altitude is less than or equal to the altitude threshold; The first strategy includes: determining the vertical speed of the unmanned device according to the first DEM information of the plot area where the unmanned device is currently located, and controlling the unmanned device to perform terrain-simulating flight according to the vertical speed, wherein the plot area is determined according to the current flight position of the unmanned device; Wherein, determining the vertical speed of the unmanned device according to the first DEM information of the plot area where the unmanned device is currently located includes: Determining a feedforward control amount of the unmanned equipment according to first DEM information of a plot area where the unmanned equipment is currently located; Determine a feedback control amount of the unmanned equipment according to the first DEM information and the actual flight altitude; The vertical speed of the unmanned equipment is determined according to the feedforward control amount and the feedback control amount.

15. An unmanned device, characterized in that: The unmanned device includes a processor and a memory; The memory is used to store a computer program and transmit the computer program to the processor; The processor is used to execute a terrain-simulating flight method according to any one of claims 1 to 13 according to instructions in the computer program.

16. A storage medium storing computer executable instructions, characterized in that: When the computer executable instructions are executed by a computer processor, they are used to perform a terrain-simulating flight method according to any one of claims 1 to 13.

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