Flight control method and device

Abstract

The invention discloses a flight control method applied to a multi-rotor unmanned aerial vehicle, and the method comprises the steps: obtaining the information of a flight environment where the unmanned aerial vehicle is located; determining a noise reduction direction according to the flight environment information; determining a target pitch angle of the rotor wing according to the noise reduction direction; and the rotor wing is controlled so that the pitch angle of the rotor wing can be kept consistent with the target pitch angle. Based on the principle of active noise reduction, the pitch angle of the rotor wing of the unmanned aerial vehicle is adaptively adjusted by analyzing the flight environment where the unmanned aerial vehicle is located so as to adapt to the demand of the urban complex environment for reducing the noise of the unmanned aerial vehicle.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of unmanned aerial vehicles, and more particularly to a flight control method and device of an unmanned aerial vehicle. BACKGROUND

[0002] Unmanned aerial vehicles are increasingly becoming a part of people's lives and are used in various application scenarios such as photography, delivery, and medical transportation. In order to prevent noise interference, traditional large aviation hubs are usually located in suburban areas. However, for unmanned aerial vehicles, limiting application scenarios to suburban areas will greatly affect the embodiment of their convenience. For example, in densely populated and complex urban areas, multi-rotor unmanned aerial vehicles are widely used for cargo transportation. The airspace situation in urban areas is more complex than in suburban areas, and the noise pollution restrictions in areas such as hospitals, schools, and residential areas are more stringent. Therefore, reducing the noise of unmanned aerial vehicles in urban application scenarios and avoiding interference with the lives of urban residents has become an important factor for the unmanned aerial vehicle industry to break through the limitations of operating areas. SUMMARY

[0003] Embodiments of the present application provide a flight control method and device of an unmanned aerial vehicle. Based on the principle of active noise reduction, the pitch angle of the rotors of the unmanned aerial vehicle is adaptively adjusted by analyzing the flight environment of the unmanned aerial vehicle to adapt to the demand of complex urban environments for reducing the noise of unmanned aerial vehicles.

[0004] In a first aspect, a flight control method of an unmanned aerial vehicle is provided. The unmanned aerial vehicle includes at least two rotors. The method includes: obtaining flight environment information of the unmanned aerial vehicle; determining a noise reduction direction according to the flight environment information; determining a target pitch angle of the rotors according to the noise reduction direction; and controlling the rotors so that the pitch angle of the rotors is equal to the target pitch angle.

[0005] In a feasible implementation, the flight environment information includes building information and / or personnel information within a predetermined range of the neighborhood of the unmanned aerial vehicle.

[0006] In a feasible implementation, the determination of the noise reduction direction according to the flight environment information includes: in a case where the flight environment information indicates that there are personnel below the unmanned aerial vehicle and the unmanned aerial vehicle is less than a first predetermined distance from the ground, taking the area below the unmanned aerial vehicle as the noise reduction direction; or, in a case where the flight environment information indicates that there is a roof below the unmanned aerial vehicle and the unmanned aerial vehicle is less than a second predetermined distance from the roof, taking the area below the unmanned aerial vehicle as the noise reduction direction; or, in a case where the flight environment information indicates that there is a window in a first direction of the unmanned aerial vehicle and the unmanned aerial vehicle is greater than a third predetermined distance from the ground, taking the first direction as the noise reduction direction.

[0007] In an implementation, the determining the target pitch angle of the rotor according to the noise reduction direction comprises: taking the noise reduction direction as a candidate noise reduction direction; obtaining a candidate pitch angle according to a pre-acquired relationship between the candidate noise reduction direction and the candidate pitch angle; and taking the candidate pitch angle as the target pitch angle.

[0008] In an implementation, the obtaining the relationship between the candidate noise reduction direction and the candidate pitch angle comprises: traversing combinations of the pitch angles of the at least two rotors with a preset unit change as an adjustment interval; recording a strongest noise direction corresponding to each of the combinations; and taking the strongest noise direction as a candidate noise reduction direction corresponding to the combination.

[0009] In an implementation, the target pitch angles of the at least two rotors have a target phase angle difference, and the controlling the rotors comprises: controlling the phase angle difference of the pitch angles of the at least two rotors to be equal to the target phase angle difference by using a same control algorithm.

[0010] In an implementation, the determining the target pitch angle of the rotor according to the noise reduction direction comprises: determining the target pitch angle according to the noise reduction direction and a rotation speed of the rotor; correspondingly, the obtaining the relationship between the candidate noise reduction direction and the candidate pitch angle comprises: obtaining the relationship between the candidate noise reduction direction and the candidate pitch angle in a case where the rotation speed of the rotor is a target rotation speed; and correspondingly, the controlling the rotors further comprises: controlling the rotation speed of the rotor to be the target rotation speed.

[0011] In an implementation, the controlling the rotors further comprises: controlling the rotors to maintain a stable rotation speed.

[0012] In an implementation, in a case where the target pitch angle changes, the controlling the rotors comprises: changing the pitch angles of the rotors to be consistent with the changed target pitch angle.

[0013] In a second aspect, the present application provides a flight control device of a UAV, the UAV comprising at least two rotors, the device comprising: a detection module configured to acquire flight environment information of the UAV; an analysis module configured to determine a noise reduction direction according to the flight environment information; a determination module configured to determine a target pitch angle of the rotors according to the noise reduction direction; and a control module configured to control the rotors so that the pitch angles of the rotors are equal to the target pitch angle.

[0014] In an implementation, the flight environment information comprises building information and / or personnel information within a preset range of the UAV.

[0015] In an implementation, the analysis module is configured to: in a case where the flight environment information indicates that there is personnel below the UAV and the UAV is less than a first preset distance from the ground, determine the direction below the UAV as the noise reduction direction; or in a case where the flight environment information indicates that there is a roof below the UAV and the UAV is less than a second preset distance from the roof, determine the direction below the UAV as the noise reduction direction; or in a case where the flight environment information indicates that there is a window in a first direction of the UAV and the UAV is greater than a third preset distance from the ground, determine the first direction as the noise reduction direction.

[0016] In an implementation, the determination module is configured to: determine the noise reduction direction as a candidate noise reduction direction; obtain a candidate pitch angle according to a relationship between the candidate noise reduction direction and the candidate pitch angle obtained in advance; and determine the candidate pitch angle as the target pitch angle. Correspondingly, before obtaining the flight environment information of the UAV, the determination module is further configured to obtain the relationship between the candidate noise reduction direction and the candidate pitch angle.

[0017] In an implementation, the obtaining of the relationship between the candidate noise reduction direction and the candidate pitch angle comprises: traversing combinations of pitch angles of the at least two rotors with a preset unit change as an adjustment interval; recording a strongest noise direction corresponding to each combination; and determining the strongest noise direction as a candidate noise reduction direction corresponding to the combination.

[0018] In an implementation, the target pitch angles of the at least two rotors have a target phase angle difference, and the control module is configured to control the phase angle difference of the pitch angles of the at least two rotors to be equal to the target phase angle difference by using a same control algorithm.

[0019] In an implementation, the analysis module is configured to determine the target pitch angle according to the noise reduction direction and a rotation speed of the rotors, and the determination module is further configured to obtain the relationship between the candidate noise reduction direction and the candidate pitch angle in a case where the rotation speed of the rotors is a target rotation speed, and the control module is further configured to control the rotation speed of the rotors to be the target rotation speed.

[0020] In an implementation, the control module is further configured to control the rotors to maintain a stable rotation speed.

[0021] In a feasible implementation, when the target pitch angle is changed, the control module is specifically configured to change the pitch angle of the rotor to be consistent with the changed target pitch angle.

[0022] In a third aspect, the present application provides a UAV flight control device, comprising a memory and a processor, the memory is configured to store a computer program, and the processor is configured to execute the method steps according to any one of the first aspect under the control of the computer program.

[0023] In a fourth aspect, the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the method steps according to any one of the first aspect.

[0024] The embodiment of the present application determines the direction most sensitive to noise by acquiring and analyzing the information of the flight environment of the UAV, and reduces the noise in the direction by controlling the pitch angle and / or rotating speed of the multiple rotors. This scheme does not need to add other hardware devices, and avoids changing the blade shape to affect the kinetic efficiency in pursuit of the noise reduction effect of the blade itself. Moreover, the noise reduction direction can be adaptively changed with the change of the flight environment of the UAV, which solves the pain point of the UAV operation in the complex airspace environment in the city.

[0025] Other features and advantages of the present application will become apparent from the following detailed description of illustrative embodiments thereof, which proceeds with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0026] The accompanying drawings incorporated in and forming a part of the specification illustrate embodiments of the present application and, together with the description, serve to explain the principles of the application.

[0027] Figure 1 is a flowchart of a UAV flight control method provided by the embodiment of the present application;

[0028] Figure 2 is a flowchart of a synchronous control method provided by the embodiment of the present application;

[0029] Figure 3 is an exemplary structural block diagram of a UAV flight control device provided by the embodiment of the present application;

[0030] Figure 4 is an exemplary structural block diagram of a UAV flight control device provided by the embodiment of the present application; DETAILED DESCRIPTION

[0031] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. Note that the relative arrangement of the components and steps illustrated in these embodiments, numerical expressions, and numerical values are merely examples, and do not limit the scope of the present application unless otherwise specifically stated.

[0032] The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the scope of the application its application or uses.

[0033] Techniques, methods, and apparatus known to those of ordinary skill in the relevant art can not be discussed in detail herein, but should be considered as part of the specification, where appropriate.

[0034] In all of the examples shown and discussed herein, any specific values should be interpreted as merely exemplary, and not as a limitation. Thus, other examples of exemplary embodiments can have different values.

[0035] Note that like reference numerals and letters indicate like items in the accompanying drawings and that, once an item is defined in one drawing, it should not have to be discussed further in subsequent drawings.

[0036] A multi-rotor unmanned aerial vehicle is a vertical take-off and landing unmanned aerial vehicle, whose flight principle is controlled by two or more rotors, which can be in the vertical direction during take-off and landing, and also has the ability to hover. The flight speed is slower than the fixed-wing unmanned aerial vehicle, the range is shorter, but the flight efficiency is higher, and it has better endurance, which is very suitable for urban low-altitude logistics scenarios with complex airspace environment. However, in the urban low-altitude area, residential distribution is extensive and irregular, and different city areas have different requirements for noise limitation, so the unmanned aerial vehicle needs to adopt a more flexible method to balance between flight efficiency, safety and noise reduction. Generally, the method of controlling rotor noise can be roughly divided into three categories. The first category is to change the shape design of the rotor, but this needs to make a certain trade-off between aerodynamic performance and noise suppression. Because the aerodynamic performance cannot be too degraded, this method has a certain upper limit for noise suppression. The second category is to adjust the flight attitude or control parameters of the rotor aircraft, so as to avoid the state of strong noise, but adjusting the flight attitude or control parameters of the aircraft can only avoid the emergence of extreme noise problems, and it is still difficult for residents near the aircraft to accept. The third category is to set actuators or excitation sources on the rotor blades to generate control force, so as to achieve the purpose of noise suppression, which needs to increase additional devices on the aircraft, increase additional cost, and also affect the aerodynamic performance.

[0037] In order to solve the noise problem of multi-rotor unmanned aerial vehicles in complex urban low-altitude scenarios, such as Figure 1As shown, the embodiment of the present application exemplarily provides a flight control method 100 of a UAV, applicable to a UAV comprising at least two rotors, the method comprising:

[0038] S101, acquiring flight environment information of the UAV.

[0039] The flight environment information in the embodiment of the present application refers to buildings, personnel, animals and other aircrafts having spatial correlation with the UAV when the UAV is flying, which can include building information within a first preset range of the UAV neighborhood, personnel information within a second preset range of the UAV neighborhood, etc., which is not limited by the embodiment of the present application. In some specific scenarios, the UAV can fly over the roof of a building, can fly in front of a window of a building, can encounter a bird flock during flight, can encounter other aircrafts, can fly over a dense crowd, can fly along the air above a river, and can land at a landing point with sporadic personnel in the surrounding, all of which constitute the flight environment of the UAV. The flight environment information characterizes the above flight environment in a concrete form, for example, the flight environment information can be digital information recognizable by the processing system of the UAV, specifically, the flight environment information can be a combination of one or more information such as objects in the flight environment, relative speed, relative distance, etc. Exemplarily, the flight environment information can be A100B10C1D0, wherein A100 represents 100 meters from the ground, B10 represents 10 meters from the nearest building in the surrounding, C1 represents that there are personnel on the ground, and D0 represents that the nearest building has no window. Exemplarily, the flight environment information can also be W|100|10, representing that there is an object 100 meters away from the UAV in the W direction of the UAV, and the relative speed between the two is 10 meters per second, wherein W can be one of a plurality of preset directions. Meanwhile, it should be understood that when the UAV is far away from the object, such as beyond the preset range in the embodiment of the present application, the UAV cannot acquire the flight environment information, or the noise of the UAV will not have a significant impact on the object.

[0040] S102, determining a noise reduction direction according to the flight environment information.

[0041] The urban low-altitude environment is complex, and also provides favorable factors for noise reduction, that is, not all areas and all body peripheral directions are sensitive to noise. For example, the unmanned aerial vehicle is close to the ground, and there is a dense crowd below it, so the direction below the unmanned aerial vehicle is more sensitive to noise. For example, the unmanned aerial vehicle flies parallel to the high-rise window of the building, and the window direction facing the unmanned aerial vehicle is more sensitive to noise. Generally, the direction more sensitive to noise is the noise reduction direction. Specifically, taking the implementation mode in the above as an example, in the case of flight environment information A100B10C1D0, the crowd 100 meters below the unmanned aerial vehicle is more sensitive to noise, and the noise reduction direction should be the direction below the unmanned aerial vehicle. In the case of flight environment information W|100|10, the W direction may be more sensitive to noise, and the noise reduction direction should be the W direction of the unmanned aerial vehicle.

[0042] In a feasible implementation mode, in the case that the flight environment information indicates that there are people below the unmanned aerial vehicle and the unmanned aerial vehicle is less than a first preset distance from the ground, the direction below the unmanned aerial vehicle is taken as the noise reduction direction. That is, in the case that the unmanned aerial vehicle is close to the ground personnel, the direction below the unmanned aerial vehicle is taken as the noise reduction direction. In another feasible implementation mode, in the case that the flight environment information indicates that there are roofs below the unmanned aerial vehicle and the unmanned aerial vehicle is less than a second preset distance from the roof, the direction below the unmanned aerial vehicle is taken as the noise reduction direction. That is, in the case that the unmanned aerial vehicle is close to the roof of the residents, the direction below the unmanned aerial vehicle is taken as the noise reduction direction. In another feasible implementation mode, in the case that the flight environment information indicates that there are windows in the first direction of the unmanned aerial vehicle and the unmanned aerial vehicle is greater than a third preset distance from the ground, the first direction is taken as the noise reduction direction. That is, in the case that the unmanned aerial vehicle flies near the high-rise window, the window direction is taken as the noise reduction direction.

[0043] It should be understood that according to different flight environment information, the processing system of the unmanned aerial vehicle can analyze the flight environment information, and determine the direction most sensitive to noise as the noise reduction direction according to the sensitivity of the flight environment to noise, the purpose of which is to reduce the influence of noise on personnel. The specific implementation modes include but are not limited to the above. In some other feasible implementation modes, the noise reduction direction can also be related to reducing the influence of noise on buildings, birds, other signals, etc.

[0044] S103, determining a target pitch angle of the rotor according to the noise reduction direction.

[0045] The rotor of the unmanned aerial vehicle is not an ideal point sound source, and the rotation of the multiple rotors has strong mutual interference, so it is difficult to deduce the relationship between the rotor control and the sound propagation rule by using a simple mathematical model. Some unmanned aerial vehicles have limited computing power, and the corresponding relationship between the state parameters of the rotors and the noise distribution is obtained in advance. For example, the state parameters of the rotors and the direction in which the noise is smallest under the control parameters can be stored in the form of a list. After the noise reduction direction is determined, the state parameters of the rotors corresponding to the noise reduction direction, i.e., the noise minimum direction, can be found. The found state parameters are the basis for subsequent adjustment of the control of the unmanned aerial vehicle. In the embodiment of the application, the pitch angle of the rotor is used as the state parameter, and it should be understood that other physical quantities representing the attitude of the rotor can also be used as the state parameter, and the application does not limit this.

[0046] In the embodiment of the application, step S103 can specifically include:

[0047] S1031, taking the noise reduction direction as a candidate noise reduction direction;

[0048] S1032, obtaining a candidate pitch angle according to the relationship between the candidate noise reduction direction and the candidate pitch angle obtained in advance;

[0049] S1033, taking the candidate pitch angle as a target pitch angle.

[0050] Obviously, the relationship between the candidate noise reduction direction and the candidate pitch angle needs to be obtained in advance corresponding to the embodiment of the application. In a feasible implementation manner, the preset unit change amount is taken as the adjustment interval, and the combinations of the pitch angles of the at least two rotors are traversed; the strongest noise direction corresponding to each combination is recorded; and the strongest noise direction is taken as the candidate noise reduction direction corresponding to the combination. Exemplarily, the relationship between the candidate noise reduction direction and the candidate pitch angle can be represented by the following corresponding relationship table:

[0051]

[0052] In other feasible implementation manners, the unmanned aerial vehicle has a powerful computing capability, and can obtain the state parameters of the rotors in real time according to the noise reduction direction and in combination with a suitable mathematical model. In other feasible implementation manners, after the unmanned aerial vehicle determines the noise reduction direction, the unmanned aerial vehicle can send relevant information including the noise reduction direction to the server end, and the server end analyzes and sends the state parameters obtained by the analysis or the control parameters derived from the state parameters back to the unmanned aerial vehicle, that is, the server shares the computing pressure of the unmanned aerial vehicle.

[0053] S104, controlling the rotors so that the pitch angle of the rotors is equal to the target pitch angle.

[0054] Once the target pitch angle is determined, the rotors can be controlled to fly according to the target pitch angle. Since the UAV has multiple rotors, and in this embodiment of the invention, it is necessary to precisely control the state parameters of each rotor to ensure the desired noise reduction direction is achieved. In one feasible implementation, a phase synchronization control algorithm is used to control the phase angle difference between the pitch angles of at least two rotors to be equal to the target phase angle difference, where the target phase angle difference is the phase angle difference between the target pitch angles of different rotors of the UAV.

[0055] For example, such as Figure 2 As shown in the illustration, this invention provides a phase synchronization control method. A virtual axis rotates at a given input speed and trajectory, where the trajectory can be provided by a cam table or interpolation. The real axis follows the virtual axis with a certain phase angle difference. A PID controller (position loop) and a motor encoder control the actual motion of the real axis to match the target motion. The real axis of each rotor of the UAV is input with a specified phase angle difference to achieve phase synchronization control of each rotor with that specified phase angle difference.

[0056] In another embodiment of the invention, step S103 specifically includes determining the target pitch angle based on the noise reduction direction and the rotor speed. Adjusting the pitch angle may affect the rotor speed. To more accurately determine the pitch angle of each rotor and obtain a better noise reduction effect, the target pitch angle is determined using two variables: the noise reduction direction and the rotor speed. Correspondingly, obtaining the relationship between candidate noise reduction directions and candidate pitch angles includes: obtaining the relationship between candidate noise reduction directions and candidate pitch angles when the rotor speed is the target speed. Controlling the rotor also includes controlling the rotor speed to the target speed. Specific implementation methods are similar to other implementation methods of step S103, and will not be described in detail here. For example, the relationship between candidate noise reduction directions, target speed, and candidate pitch angles can be represented by the following correspondence table:

[0057]

[0058] S105. When the target pitch angle changes, change the rotor pitch angle to match the changed target pitch angle.

[0059] In complex urban low-altitude scenarios, flight environment information is frequently changing, and correspondingly, the noise reduction direction also changes frequently. It is necessary to control the rotor accordingly when the target pitch angle obtained based on the flight environment information changes. In this embodiment of the invention, this specifically includes changing the rotor's pitch angle to maintain consistency with the target pitch angle. The ability to adaptively change the noise reduction direction as the flight environment changes is also an advantage of this embodiment of the invention compared to other UAV noise reduction methods.

[0060] It should be understood that, in the embodiments of the present application, by analyzing the flight environment information of the UAV, the direction most sensitive to noise is determined, and based on the direction, the state parameter of the rotor of the UAV is determined, the UAV is controlled to operate at the state parameter, so that the noise generated in the direction is minimized, and the noise impact of the UAV operation on the surrounding area is reduced. In other embodiments of the present application, the direction least sensitive to noise can also be determined by the flight environment information, and the UAV is controlled to generate the maximum noise in the direction in a similar manner as in the above embodiments of the present application, so that the other directions are at least not affected by extreme noise.

[0061] In some possible implementations, the rotors of the UAV in the above-mentioned various embodiments of the present application have a fixed rotating speed. Specifically, the rotating speed of the rotors can be different in different flight stages of the UAV, for example, the rotating speed in the take-off stage and the rotating speed in the cruising stage can be different, but the rotating speed in each stage is fixed. When the UAV has multiple rotors, the fixed rotating speeds of the rotors can be the same or different. Correspondingly, in the above-mentioned various embodiments of the present application, the control of the rotors also includes maintaining a stable rotating speed of the rotors in the same flight stage.

[0062] As shown in the embodiment of the present application, Figure 3 The embodiment of the present application exemplarily provides a flight control device 300 of a UAV, the UAV comprising at least two rotors, the device 300 comprising: a detection module 301 configured to acquire flight environment information of the UAV; an analysis module 302 configured to determine a noise reduction direction according to the flight environment information; a determination module 303 configured to determine a target pitch angle of the rotors according to the noise reduction direction; and a control module 304 configured to control the rotors so that the pitch angle of the rotors is equal to the target pitch angle.

[0063] In a possible implementation, the flight environment information comprises building information and / or personnel information within a preset range of the UAV.

[0064] In a possible implementation, the analysis module 302 is specifically configured to: in a case where the flight environment information indicates that there is personnel below the UAV and the UAV is less than a first preset distance from the ground, taking the direction below the UAV as the noise reduction direction; or, in a case where the flight environment information indicates that there is a roof below the UAV and the UAV is less than a second preset distance from the roof, taking the direction below the UAV as the noise reduction direction; or, in a case where the flight environment information indicates that there is a window in a first direction of the UAV and the UAV is greater than a third preset distance from the ground, taking the first direction as the noise reduction direction.

[0065] In an implementation, the determining module 303 is specifically configured to: take the noise reduction direction as a candidate noise reduction direction; obtain the candidate pitch angle according to a pre-acquired relationship between the candidate noise reduction direction and the candidate pitch angle; and take the candidate pitch angle as the target pitch angle.

[0066] In an implementation, obtaining the relationship between the candidate noise reduction direction and the candidate pitch angle comprises: traversing combinations of the pitch angles of the at least two rotors with a preset unit change as an adjustment interval; recording the strongest noise direction corresponding to each combination; and taking the strongest noise direction as the candidate noise reduction direction corresponding to the combination.

[0067] In an implementation, the target pitch angles of the at least two rotors have a target phase angle difference, and the control module 304 is specifically configured to: control the phase angle difference of the pitch angles of the at least two rotors to be equal to the target phase angle difference by using a same control algorithm.

[0068] In an implementation, the analysis module 302 is specifically configured to: determine the target pitch angle according to the noise reduction direction and the rotating speed of the rotor; and correspondingly, the determining module 303 is further configured to: obtain the relationship between the candidate noise reduction direction and the candidate pitch angle in a case where the rotating speed of the rotor is a target rotating speed; and correspondingly, the control module 304 is further configured to: control the rotating speed of the rotor to be the target rotating speed.

[0069] In an implementation, the control module 304 is further configured to: control the rotor to maintain a stable rotating speed.

[0070] In an implementation, in a case where the target pitch angle changes, the control module 304 is specifically configured to: change the pitch angle of the rotor to be consistent with the changed target pitch angle.

[0071] Figure 4 An exemplary structural block diagram of a flight control device 400 of a UAV is exemplarily given, the device can be an airborne equipment of the UAV, or can be located in the cloud of a UAV control system, the device 400 comprises a memory 401 and a processor 402, the memory 401 is used for storing a computer program, and the processor 402 is used for executing the method steps shown in any of the embodiments under the control of the computer program. Figure 1 The method steps shown in any of the embodiments.

[0072] The present application can be a system, a method, and / or a computer program product. The computer program product can include a computer readable storage medium (or media) having computer readable program instructions thereon for causing a processor to carry out aspects of the present application.

[0073] Computer readable storage media can be tangible storage media which can retain and store instructions for use by an instruction execution device. Computer readable storage media can be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer readable storage media include the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch-cards or raised structures in a groove having instructions recorded thereon, and any suitable combination of the foregoing. A computer readable storage medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber-optic cable), or electrical signals transmitted through a wire.

[0074] Computer readable program instructions described herein can be downloaded to respective computing / processing devices from a computer readable storage medium or to an external computer or external storage device via a network, for example, the Internet, a local area network, a wide area network and / or a wireless network. The network can comprise copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and / or edge servers. A network adapter card or network interface in each computing / processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium within the respective computing / processing device.

[0075] Computer readable program instructions for carrying out operations of the present application can be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer readable program instructions can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider). In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate array (FPGA), or programmable logic array (PLA) can execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present application.

[0076] The computer readable program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0077] The computer readable program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0078] The computer readable program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable data processing apparatus or other device to produce a computer implemented process such that the instructions which execute on the computer, other programmable data processing apparatus, or other device implement the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0079] The flow diagrams and block diagrams in the drawings are presented to illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present application. In this regard, each block in the flow diagrams and block diagrams can represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical functions ("instructions"). In some alternative implementations, the functions noted in the blocks can occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks can sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and / or flowchart illustrations, and combinations thereof, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and

[0080] Embodiments of the application have been described above with the understanding that these embodiments are exemplary, and are not exhaustive, and are not limited to the embodiments disclosed. Many modifications and variations of this application can be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms to be used in the description is intended to best describe the principles of the embodiments, practical application, or improvement to the art in the marketplace, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein. The scope of the application is defined by the appended claims.

Claims

1. A flight control method of a drone, characterized by, The unmanned aerial vehicle comprises at least two rotors, and the method comprises: obtaining flight environment information of the unmanned aerial vehicle; determining a noise reduction direction according to the flight environment information; determining a target pitch angle of the rotors according to the noise reduction direction; controlling the rotors so that the pitch angles of the rotors are equal to the target pitch angle.

2. The method of claim 1, wherein, The flight environment information comprises building information and / or personnel information within a preset range adjacent to the unmanned aerial vehicle.

3. The method of claim 2, wherein, The determination of the noise reduction direction according to the flight environment information comprises: in the case that the flight environment information indicates that there is personnel below the unmanned aerial vehicle and the unmanned aerial vehicle is less than a first preset distance from the ground, taking the direction below the unmanned aerial vehicle as the noise reduction direction; or in the case that the flight environment information indicates that there is a roof below the unmanned aerial vehicle and the unmanned aerial vehicle is less than a second preset distance from the roof, taking the direction below the unmanned aerial vehicle as the noise reduction direction; or in the case that the flight environment information indicates that there is a window in a first direction of the unmanned aerial vehicle and the unmanned aerial vehicle is greater than a third preset distance from the ground, taking the first direction as the noise reduction direction.

4. The method of claim 1, wherein, The determination of the target pitch angle of the rotors according to the noise reduction direction comprises: taking the noise reduction direction as a candidate noise reduction direction; obtaining a candidate pitch angle according to a previously obtained relationship between the candidate noise reduction direction and the candidate pitch angle; taking the candidate pitch angle as the target pitch angle. Correspondingly, before the obtaining of the flight environment information of the unmanned aerial vehicle, the method further comprises: obtaining the relationship between the candidate noise reduction direction and the candidate pitch angle.

5. The method of claim 4, wherein, The obtaining of the relationship between the candidate noise reduction direction and the candidate pitch angle comprises: traversing combinations of the pitch angles of the at least two rotors with a preset unit change as an adjustment interval; recording a strongest noise direction corresponding to each of the combinations; taking the strongest noise direction as a candidate noise reduction direction corresponding to the combination.

6. The method of claim 1, wherein, The target pitch angles of the at least two rotors have a target phase angle difference, and the control of the rotors comprises: controlling the phase angle difference of the pitch angles of the at least two rotors to be equal to the target phase angle difference by using a same control algorithm.

7. The method of claim 5, wherein, The determination of the target pitch angle of the rotors according to the noise reduction direction comprises: determining the target pitch angle according to the noise reduction direction and the rotation speed of the rotors. Correspondingly, the obtaining of the relationship between the candidate noise reduction direction and the candidate pitch angle comprises: in the case that the rotation speed of the rotors is a target rotation speed, obtaining the relationship between the candidate noise reduction direction and the candidate pitch angle. Correspondingly, the control of the rotors further comprises: controlling the rotation speed of the rotors to be the target rotation speed.

8. The method of claim 1, wherein, The control of the rotors further comprises: controlling the rotors to maintain a stable rotation speed.

9. The method of claim 1, wherein, In the case that the target pitch angle changes, the control of the rotors comprises: changing the pitch angles of the rotors to be consistent with the changed target pitch angle.

10. An unmanned aerial vehicle flight control device comprising a memory and a processor, wherein, The processor is configured to obtain and execute the code in the memory to perform the method according to any one of claims 1 to 9.

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