Unmanned aerial vehicle landing longitudinal height control method and device based on flap parameter control

Abstract

The invention discloses an unmanned aerial vehicle landing longitudinal height control method and device based on flap parameter control, the device comprises an elevator control structure, a flap control structure and a switching device, and the method comprises the following steps that S1, an unmanned aerial vehicle obtains landing information and lands according to the landing information; s2, after the unmanned aerial vehicle reaches the initial landing height, the elevator control structure is adopted to control the unmanned aerial vehicle to fly horizontally; s3, in the gliding stage of the unmanned aerial vehicle, the control structure of the unmanned aerial vehicle is switched to a flap control structure from the elevator control structure through a switching device; and S4, after the flap control structure controls the unmanned aerial vehicle to slide downwards until the unmanned aerial vehicle falls to the ground, the unmanned aerial vehicle decelerates until the unmanned aerial vehicle stops. Landing of the unmanned aerial vehicle is directly controlled through the elevator control structure and the flap control structure, the rapidity and control precision of height control are improved, and high-frequency interference during landing is effectively restrained.

Description

Technical Field

[0001] The present invention relates to the field of flight control of aerial vehicles, and in particular to a method and device for controlling the longitudinal height of an unmanned aerial vehicle (UAV) landing based on flap parameter control. Background Art

[0002] As one of the key technologies of UAVs, the autonomous landing control technology is directly related to the safe recovery of UAVs. However, during the automatic landing process, situations such as altitude loss of the UAV after being interfered by the outside world, repeatedly crossing the glide path, and large sink rate touchdown caused thereby will have a negative impact on the use and safety of the UAV. Therefore, it is very meaningful to study the longitudinal high anti-interference and high-precision altitude control technology for UAV landing to improve the landing safety.

[0003] The conventional altitude control strategy is that the elevator controls the altitude by adjusting the pitch angle, changing the angle of attack, and indirectly changing the lift. This strategy has the problem of insufficient ability to resist high-frequency interference: due to the large pitch moment of inertia of the UAV, the process of generating a pitch moment by the elevator to change the pitch angle, and then changing the angle of attack and lift is slow. Therefore, the process of the elevator controlling the altitude has a large lag, and the response to high-frequency interference is not timely, resulting in the situation that the UAV often repeatedly crosses the glide path and touches down with a large sink rate when tracking the glide path. In order to improve the ability of the system to resist high-frequency interference, some researchers have proposed a control strategy of using flaps to control the altitude (the elevator is changed to control the pitch angle). The flap can generate a direct force and can quickly change the lift, so it can resist high-frequency interference. However, the deflection angle of the flap is limited, and the generated direct force is limited, and it cannot resist low-frequency interference with a large amplitude.

[0004] Therefore, there is an urgent need to provide a solution for a method of controlling the longitudinal height of a UAV landing based on flap parameter control. Summary of the Invention

[0005] In order to solve the above problems, the technical solution of the present invention provides a method and device for controlling the longitudinal height of a UAV landing based on flap parameter control, which can enable the UAV to resist high-frequency interference during the landing process.

[0006] According to the first aspect embodiment of the technical solution of the present invention, a method for controlling the longitudinal height of a UAV landing based on flap parameter control is provided, including an elevator control structure, a flap control structure, and a switching device. The method includes the following steps:

[0007] S1. The UAV obtains landing information and lands according to the landing information;

[0008] S2. After the UAV reaches the initial landing height, the elevator control structure is used to control the UAV to fly level;

[0009] S3. During the gliding phase of the UAV, the control structure of the UAV is switched from the elevator control structure to the flap control structure through a switching device;

[0010] S4. After the flap control structure controls the UAV to glide until it lands, the UAV decelerates until it stops.

[0011] In the above solution, in step S1, the landing information includes a landing trajectory and a pitch angle, and the landing trajectory includes an approach level flight segment, a gliding segment, and a decelerating taxiing segment.

[0012] In the above solution, in step S2, after the UAV reaches the initial landing height, it starts to land and enters the approach level flight segment. The flight speed of the UAV when entering the approach level flight segment is the flight speed at which the UAV maintained level flight at the previous moment.

[0013] In the above solution, in step S2, the elevator control structure controls the pitch angle and elevator deflection of the UAV to keep the flight height and pitch angle of the UAV within the deviation threshold range of the landing trajectory and the pitch angle.

[0014] In the above solution, in step S3, after the UAV enters the gliding segment, when the deviation of the height and pitch angle of the UAV is within the deviation threshold range of the landing trajectory and the pitch angle, the control structure of the UAV is switched from the elevator control structure to the flap control structure through a switching device.

[0015] In the above solution, in step S4, the flap control structure controls the flap deflection of the UAV to keep the flight height of the UAV within the deviation threshold range of the landing trajectory.

[0016] In the above solution, in step S1, the landing information further includes the airspeed in the gliding segment, and the airspeed in the gliding segment is controlled through a throttle control structure.

[0017] In the above solution, the airspeed in the gliding segment is calculated according to the aerodynamic data and weight information of the UAV.

[0018] According to the second aspect embodiment of the technical solution of the present invention, a UAV landing longitudinal height control device based on flap parameter control is provided. The device is used to implement the UAV landing longitudinal height control method based on flap parameter control described in any one of the above solutions. The device includes:

[0019] A landing module, configured to obtain landing information for the UAV and perform landing according to the landing information;

[0020] A level flight module, configured to control the UAV to fly level after it reaches the initial landing altitude by using an elevator control structure;

[0021] A gliding module, configured to switch the control structure of the UAV from the elevator control structure to a flap control structure by means of a switching device during the gliding phase of the UAV;

[0022] A deceleration module, configured to control the UAV to decelerate until it stops after the flap control structure controls the UAV to glide until it lands.

[0023] According to an embodiment of the third aspect of the technical solution of the present invention, an electronic device is provided, and the electronic device includes:

[0024] A memory storing executable instructions;

[0025] A processor that runs the executable instructions in the memory to implement the method described in any one of the above solutions.

[0026] Advantages of the present invention:

[0027] A method and device for controlling the longitudinal height of a UAV landing based on flap parameter control disclosed in the present invention directly control the landing of the UAV through an elevator control structure and a flap control structure, improving the rapidity and control accuracy of height control, and effectively suppressing high-frequency interference during landing; the flap is located near the center of gravity of the UAV, and the influence of flap deflection on the pitching moment of the aircraft can be ignored. The longitudinal height control of the UAV with flaps that can deflect up and down around the stabilizer is easy to implement in engineering; both the elevator control structure and the flap control structure are independent control structures and do not interfere with each other, ensuring the stability of the entire landing process. Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on the structures shown in these drawings without creative efforts.

[0029] Figure 1 It is a flowchart of the method for controlling the longitudinal height of a UAV landing based on flap parameter control provided by the present invention;

[0030] Figure 2 It is a control structure diagram of the method for controlling the longitudinal height of a UAV landing based on flap parameter control provided by the present invention;

[0031] Figure 3Schematic diagram of the landing trajectory of the UAV landing longitudinal height control method provided by the present invention based on flap parameter control;

[0032] Figure 4 Sliding trajectory diagrams before and after flap parameter control during the UAV landing overweight in the embodiment of the present invention;

[0033] Figure 5 Curve diagram of the height deviation before and after flap parameter control during the UAV landing overweight in the embodiment of the present invention.

[0034] The realization, functional characteristics and advantages of the object of the present invention will be further described with reference to the embodiments and the accompanying drawings. Detailed implementation manners

[0035] Here, the exemplary embodiments will be described in detail, and the examples are shown in the accompanying drawings. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation manners described in the following exemplary embodiments do not represent all implementation manners consistent with the present disclosure. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0036] The terms "first", "second", etc. in the specification and claims of the present disclosure are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein.

[0037] In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0038] Multiple, including two or more.

[0039] And / or, it should be understood that for the term "and / or" used in the present disclosure, it is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. These three situations.

[0040] As Figures 1 to 3 shown, an embodiment of the technical solution of the present invention provides a UAV landing longitudinal height control method based on flap parameter control, including an elevator control structure, a flap control structure and a switching device. The method includes the following steps:

[0041] S1. The drone obtains landing information and lands according to the landing information.

[0042] S2. After the drone reaches the initial landing altitude, an elevator control structure is used to control the drone to fly horizontally.

[0043] S3. During the gliding phase of the drone, a switching device is used to switch the control structure of the drone from the elevator control structure to a flap control structure.

[0044] S4. After the flap control structure controls the drone to glide until it lands, the drone decelerates until it stops.

[0045] In step S1, the landing information includes a landing trajectory and a pitch angle. The landing trajectory includes an approach horizontal flight segment, a gliding segment, and a deceleration taxiing segment.

[0046] Step S2 specifically includes:

[0047] After the drone reaches the initial landing altitude, it starts to land and enters the approach horizontal flight segment. The flight speed of the drone when entering the approach horizontal flight segment is the flight speed at which the drone maintained horizontal flight at the previous moment. In a preferred embodiment, the initial landing altitude is 150 m.

[0048] The elevator control structure controls the pitch angle and elevator deflection of the drone to keep the flight altitude and pitch angle of the drone within the deviation threshold range of the landing trajectory and the preset pitch angle. Specifically, a PID controller and a PD controller are used to control the pitch angle and elevator deflection of the drone.

[0049] If the flight altitude of the drone exceeds the deviation threshold range during landing, the PID controller is used to control the elevator control structure to change the pitch angle to adjust the flight altitude. The elevator control structure formula is as follows:

[0050]

[0051] In the formula, H g is the landing altitude command; H is the real-time altitude of the drone; is the change rate of the landing altitude command; is the landing lift speed of the drone; θ trim is the landing trim pitch angle; θ g is the pitch angle command; is the altitude control proportional coefficient; is the altitude control integral coefficient; is the altitude control differential coefficient.

[0052] If the pitch angle deviation of the drone exceeds the pitch angle deviation threshold range during landing, the elevator of the elevator control structure is controlled by the PD controller to adjust the pitch angle of the drone. The elevator control structure formula is as follows:

[0053]

[0054] Where, θ is the real-time pitch angle of the UAV; q is the real-time pitch rate of the UAV; δ e It is the elevator servo command; Control the proportional coefficient for the pitch angle; It is the differential coefficient of pitch angle control.

[0055] Step S3 specifically includes:

[0056] After the drone enters the gliding stage, if the deviation of the drone's altitude and pitch angle is within the deviation threshold of the landing trajectory and pitch angle, the control structure of the drone is switched from the elevator control structure to the flap control structure through the switching device, that is, the elevator control structure is required to control the drone to stably track the gliding line before switching to the flap control structure. The elevator control structure and the flap control structure are both independent control structures that do not interfere with each other, ensuring the stability of the entire landing process.

[0057] The present invention switches to flap control structure parameter control in the glide path, thereby improving the rapidity and control accuracy of height control and effectively suppressing high-frequency interference during landing; since the flap is located near the center of gravity of the UAV, the influence of the flap deflection on the pitch moment of the aircraft can be ignored, the flap can be deflected up and down around the stabilizer to control the landing longitudinal height of the UAV, and the control structure is easy to implement in engineering.

[0058] Step S4 specifically includes:

[0059] Preset the trim value δ for flap deflection f0 , δ f0 The selection should be at the neutral position of the flap deflection to ensure that the flap has a large up and down deflection margin.

[0060] Preferably, the flap control structure performs [-H] on the altitude deviation and the rate of change of altitude deviation of the UAV. lim ,H lim ]and The limiting process allows the direct force to be used exclusively to control small altitude deviations without losing its control speed. For the altitude control of the UAV, the damping is enhanced through the flap control structure, which is conducive to its stable tracking of the glide path.

[0061] The flap control structure controls the flap deflection of the UAV so that the flight altitude of the UAV is maintained within the deviation threshold range of the landing trajectory, wherein the flap deflection of the UAV is controlled by a PI controller.

[0062] Preferably, the descending section includes a deep descending section and a shallow descending section. The deep descending section is mainly used for rapid descent and preliminary adjustment, while the shallow descending section is used for precise control and deceleration to ensure that the UAV touches the ground smoothly. By setting the deep descending section and the shallow descending section, the descending process of the UAV can be controlled more precisely, ensuring a safe and stable landing, and significantly improving the reliability and safety of the UAV landing. The switching process of the UAV's control structure from the elevator control structure to the flap control structure can be carried out in the deep descending section or in the shallow descending section. Preferably, it is carried out in the deep descending section, which can enable the flap control structure to participate in the control earlier, ensuring the stability of the UAV landing. Moreover, during the rapid descent in the deep descending section, the flap control structure is required to participate in the control to maintain the stability of the descent.

[0063] Furthermore, in the descending section, the UAV lands along the landing trajectory. According to the remaining flight distance X from the touchdown point and the deep descending angle γ and the shallow descending angle γ of the UAV during landing D when landing, the target height of the current UAV is calculated in real time. S

[0064] In the deep descending section and the shallow descending section, the trajectory height calculation formula is:

[0065]

[0066] In the formula, H D is the relative height of the UAV corresponding to the X coordinate point in the deep descending section; H S is the relative height of the UAV corresponding to the X coordinate point in the shallow descending section; X is the remaining flight distance of the UAV from the touchdown point; H f is the starting height of the shallow descending section; X1 is the distance between the starting point of the shallow descent and the touchdown point; X t is the touchdown point; γ D is the deep descending angle; γ S is the shallow descending angle.

[0067] Therefore, when the UAV is in the deep descending section, the target height is H D , and when it is in the shallow descending section, the target height is H S .

[0068] Based on this embodiment, for the segmented processing of the descending section, the calculation formulas of the flap control structure in the deep descending section and the shallow descending section are as follows:

[0069]

[0070] In the formula, δ f0 is the neutral position of the flap; is the flap proportional control parameter; is the flap differential control parameter; δ fis the flap servo command; H is the real-time altitude of the UAV; is the change rate of the landing altitude command in the deep glide segment; is the change rate of the landing altitude command in the shallow glide segment; is the landing lift and descent speed of the UAV.

[0071] The landing information also includes the airspeed in the glide segment, and the throttle control structure controls the airspeed in the glide segment. The airspeed in the glide segment is calculated based on the aerodynamic data and weight information of the UAV, and the trimmed airspeed V in the deep glide segment and the shallow glide segment is pre-set g . The UAV maintains the initial flight speed in the approach level flight segment and needs to be adjusted to the trimmed airspeed V g after entering the glide segment and maintain it until the end of the glide segment.

[0072] The airspeed in the glide segment is controlled by a PI controller. If the speed deviation of the UAV exceeds the deviation threshold of the trimmed airspeed V g , the PI controller controls the throttle change to adjust the flight speed, and the throttle control structure formula is as follows:

[0073]

[0074] where V g is the airspeed command in the deep glide and shallow glide segments; V is the real-time airspeed of the aircraft; δ Ttrim is the landing trimmed throttle; δ T is the throttle command; is the airspeed proportional control coefficient; is the airspeed integral control coefficient.

[0075] Furthermore, after entering the deceleration taxiing segment, the throttle is given according to the current speed to apply brakes for deceleration until the UAV stops.

[0076] According to the second aspect embodiment of the technical solution of the present invention, a UAV landing longitudinal altitude control device based on flap parameter control is provided. The device is used to implement the above-mentioned UAV landing longitudinal altitude control method based on flap parameter control. The device includes:

[0077] A landing module, which is used for the UAV to obtain landing information and land according to the landing information;

[0078] A level flight module, which is used for the UAV to control the level flight of the UAV by using an elevator control structure after reaching the initial landing altitude;

[0079] A glide module, which is used for the UAV to switch the control structure of the UAV from the elevator control structure to the flap control structure through a switching device during the glide stage;

[0080] A deceleration module, which is used for the flap control structure to control the UAV to glide until landing, and then the UAV decelerates until it stops.

[0081] According to an embodiment of the third aspect of the technical solution of the present invention, an electronic device is provided, and the electronic device includes:

[0082] A memory storing executable instructions;

[0083] A processor that runs the executable instructions in the memory to implement the above method.

[0084] Embodiment

[0085] In a strong wind environment, the drone descends from a relative height of 150 m to 100 m.

[0086] As Figure 4 and Figure 5 shown, the drone first uses the elevator control structure to control the altitude, and switches to the flap control structure after the moment of 11560.11 s. As Figure 4 and Figure 5 can be seen, when the elevator control structure is in control and the flap control structure is not participating in the control, affected by the strong wind, the maximum altitude deviation is 8.3 m below the line, and there will be altitude fluctuations. After the moment of 11560.11 s, it switches to the flap control structure to participate in the control, and the altitude deviation of the drone is controlled within 1.2 m, and the altitude tracking is significantly stable.

[0087] It should be noted that in this article, the terms "including", "comprising" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including that element.

[0088] The serial numbers of the above embodiments of the present invention are only for description and do not represent the superiority or inferiority of the embodiments.

[0089] Through the description of the above embodiments, those skilled in the art can clearly understand that the above implementation methods can be implemented by means of software plus a necessary general hardware platform. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. The computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disc), and includes several instructions for causing a terminal (which can be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0090] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit of the present invention and the scope protected by the claims. All of these are within the protection scope of the present invention.

Claims

1. A method for controlling the longitudinal height of an unmanned aerial vehicle during landing based on flap parameter control, characterized in that It includes an elevator control structure, a flap control structure and a switching device, and the method includes the following steps: S1. The UAV obtains landing information and lands according to the landing information; S2. After the UAV reaches the initial landing height, the elevator control structure is used to control the UAV to fly horizontally; S3. During the gliding stage of the UAV, the control structure of the UAV is switched from the elevator control structure to the flap control structure through the switching device; S4. After the flap control structure controls the UAV to glide until it lands, the UAV decelerates until it stops.

2. The method for controlling the longitudinal height of an unmanned aerial vehicle during landing based on flap parameter control according to claim 1, wherein In step S1, the landing information includes a landing trajectory and a pitch angle, and the landing trajectory includes an approach horizontal flight segment, a gliding segment and a decelerating taxiing segment.

3. The method for controlling the longitudinal height of a UAV landing based on flap parameter control according to claim 2, wherein, In step S2, after the UAV reaches the initial landing height, it starts to land and enters the approach horizontal flight segment. The flight speed of the UAV when entering the approach horizontal flight segment is the flight speed at which the UAV maintained horizontal flight at the previous moment.

4. The method for controlling the longitudinal height of an unmanned aerial vehicle landing based on flap parameter control according to claim 2, wherein In step S2, the elevator control structure controls the pitch angle and elevator deflection of the UAV to keep the flight height and pitch angle of the UAV within the deviation threshold range of the landing trajectory and the pitch angle.

5. The method for controlling the longitudinal height of an unmanned aerial vehicle during landing based on flap parameter control according to claim 2, wherein, In step S3, after the UAV enters the gliding segment, when the deviation of the height and pitch angle of the UAV is within the deviation threshold range of the landing trajectory and the pitch angle, the control structure of the UAV is switched from the elevator control structure to the flap control structure through the switching device.

6. The method for controlling the longitudinal height of an unmanned aerial vehicle landing based on flap parameter control according to claim 1, wherein In step S4, the flap control structure controls the flap deflection of the UAV to keep the flight height of the UAV within the deviation threshold range of the landing trajectory.

7. The method for controlling the longitudinal height of an unmanned aerial vehicle landing based on flap parameter control according to claim 1, wherein In step S1, the landing information further includes the airspeed of the gliding segment, and the airspeed of the gliding segment is controlled by the throttle control structure.

8. The method for controlling the longitudinal height of an unmanned aerial vehicle during landing based on flap parameter control according to claim 7, wherein The airspeed of the gliding segment is calculated according to the aerodynamic data and weight information of the UAV.

9. An unmanned aerial vehicle landing longitudinal height control device based on flap parameter control, characterized in that, The device is used to implement the method for controlling the longitudinal height of the UAV landing based on flap parameter control according to any one of claims 1-8. The device includes: A landing module, which is used for the UAV to obtain landing information and land according to the landing information; A horizontal flight module, which is used for the UAV to fly horizontally by using the elevator control structure after reaching the initial landing height; A gliding module, which is used for the UAV to switch the control structure of the UAV from the elevator control structure to the flap control structure through the switching device during the gliding stage; A decelerating module, which is used for the flap control structure to control the UAV to glide until it lands, and then the UAV decelerates until it stops.

10. An electronic device, characterized in that, The electronic device includes: A memory, which stores executable instructions; A processor, and the processor runs the executable instructions in the memory to implement the method according to any one of claims 1-8.

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