Multirotor airspeed envelope protection methods, equipment and computer-readable storage media

Abstract

This invention discloses a method, device, and computer-readable storage medium for airspeed envelope protection of multi-rotor aircraft. The method includes: establishing an airspeed mathematical model; determining the correspondence between the maximum tilt angle and the maximum steady-state airspeed based on the airspeed mathematical model, and obtaining tilt angle limiting parameters introduced into attitude control based on the correspondence; calculating the transient airspeed based on the airspeed mathematical model, attitude measurement, and acceleration measurement, and executing corresponding airspeed protection procedures based on the detection result of the transient airspeed. This invention realizes an airspeed envelope protection scheme that utilizes dynamic principles and does not rely on traditional airspeed sensor observations, effectively saving hardware and maintenance costs and ensuring flight safety.

Description

Technical Field

[0001] This invention relates to the field of unmanned aerial vehicle technology, and in particular to a method, device and computer-readable storage medium for protecting the airspeed envelope of a multi-rotor aircraft. Background Technology

[0002] In existing technologies, airspeed envelope protection is of great significance for the structural load safety of aircraft. Traditional airspeed envelope protection measures for aircraft are generally based on airspeed indicator information according to the dynamic / static pressure principle, and are actively protected by the pilot or flight control system to ensure that the airspeed does not exceed the envelope.

[0003] However, for typical multirotor aircraft, due to differences in control methods or interference from the installation environment, they may not have airspeed gauges based on dynamic / static pressure principles. This poses a challenge to the envelope protection function of multirotors.

[0004] Therefore, how to utilize the principles of dynamics to achieve airspeed envelope protection without relying on traditional airspeed sensor observations has become an urgent technical problem to be solved. Summary of the Invention

[0005] To address the aforementioned technical deficiencies in the prior art, this invention proposes a method for protecting the airspeed envelope of a multi-rotor aircraft, the method comprising:

[0006] Establishing a mathematical model of airspeed Where m is mass, g is gravitational acceleration, θ is tilt angle, V is airspeed, and k1(θ), k2(θ), and k3(θ) are the first, second, and third order drag coefficient functions, respectively.

[0007] The correspondence between the maximum tilt angle and the maximum steady-state airspeed is determined based on the airspeed mathematical model, and the tilt angle limit parameter introduced into attitude control is obtained based on the correspondence.

[0008] The transient airspeed is calculated based on the airspeed mathematical model, attitude measurement, and acceleration measurement, and the corresponding airspeed protection procedure is executed based on the detection result of the transient airspeed.

[0009] Optionally, establishing the airspeed mathematical model includes:

[0010] Establish a mathematical model for calculating airspeed (ma) x =-(k1(θ)·V+k2(θ)·V 2 +k3(θ)·V 3 )+mg tanθ, where a x For acceleration;

[0011] Determine the kinematic constraints satisfied by the longitudinal motion:

[0012]

[0013] Among them, V wind For the incoming airflow speed, V gnd For ground speed.

[0014] Optionally, establishing the airspeed mathematical model further includes:

[0015] For steady flow fields with no wind, constant wind, and slowly changing gusts, take

[0016] For the non-stationary flow field of gusts, steady state is taken

[0017] The airspeed mathematical model is established by combining the airspeed calculation mathematical model with the kinematic constraints satisfied by the longitudinal motion.

[0018] Optionally, determining the correspondence between the maximum tilt angle and the maximum steady-state airspeed based on the airspeed mathematical model, and obtaining the tilt angle limit parameter introduced into attitude control based on the correspondence, includes:

[0019] definition At that time, V, determined by the aforementioned airspeed mathematical model, is the equilibrium airspeed V at a given tilt angle θ. e (θ), where each tilt angle θ has a unique corresponding equilibrium airspeed V. e For a given tilt angle θ, the following relationship exists:

[0020] When V <V e When (θ),

[0021] When V>V e When (θ),

[0022] Combined with balanced airspeed V e (θ) represents the stable equilibrium state of the airspeed V at an inclination angle θ. Determine the relationship between the inclination angle θ and the equilibrium airspeed V. e The mapping relationship between (θ);

[0023] Limiting the maximum tilt angle θ through a control algorithm max At that time, the steady-state airspeed is determined to be limited to the maximum value V. e_max .

[0024] Optionally, the step of determining the correspondence between the maximum tilt angle and the maximum steady-state airspeed based on the airspeed mathematical model, and obtaining the tilt angle limit parameter introduced into attitude control based on the correspondence, further includes:

[0025] Through flight tests, different tilt angle limits θ were set each time. MAXUsing a step size of 1 degree, iterate through all possible tilt angle constraints θ. MAX Scope of application;

[0026] The maximum tilt angle θ was determined based on the ergonomic data from the flight tests. max With maximum steady-state airspeed V e_max A table showing the numerical correspondence between them.

[0027] Optionally, the step of determining the correspondence between the maximum tilt angle and the maximum steady-state airspeed based on the airspeed mathematical model, and obtaining the tilt angle limit parameter introduced into attitude control based on the correspondence, further includes:

[0028] Given an airspeed envelope V max And with a 25% margin for gusts, determine the maximum steady-state airspeed V. e_max = (1-25%)*V max ;

[0029] The maximum tilt angle θ is determined based on the numerical correspondence table. max And the maximum tilt angle θ max Set as the tilt angle limit parameter for the attitude control algorithm.

[0030] Optionally, the step of calculating the transient airspeed based on the airspeed mathematical model, attitude measurement, and acceleration measurement, and executing a corresponding airspeed protection procedure based on the detection result of the transient airspeed, includes:

[0031] Whether the transient airspeed calculated at a frequency of 1Hz exceeds the threshold;

[0032] When the transient airspeed exceeds the threshold, the corresponding airspeed protection procedure is executed.

[0033] Optionally, the step of calculating the transient airspeed based on the airspeed mathematical model, attitude measurement, and acceleration measurement, and executing the corresponding airspeed protection procedure based on the transient airspeed detection result, further includes:

[0034] In k1*V max ≤V <k2*V max At that time, an alarm message is sent to the ground station, and the remote crew is required to continuously monitor the airspeed status;

[0035] In k2*V max ≤V <V max At that time, the target speed is actively reduced and the tilt angle is decreased through the flight controller until the airspeed is lower than k1*V. max ;

[0036] When V≥V max At that time, the aircraft is controlled by the flight controller to decelerate to a hovering state and begin returning to base or landing;

[0037] Among them, k1 <k2。

[0038] The present invention also proposes a multi-rotor airspeed envelope protection device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the computer program is executed by the processor, it implements the steps of the multi-rotor airspeed envelope protection method as described in any of the preceding claims.

[0039] The present invention also proposes a computer-readable storage medium storing a multi-rotor airspeed envelope protection program, which, when executed by a processor, implements the steps of the multi-rotor airspeed envelope protection method as described in any of the preceding claims.

[0040] The present invention provides a multi-rotor airspeed envelope protection method, device, and computer-readable storage medium, which establishes an airspeed mathematical model; determines the correspondence between the maximum tilt angle and the maximum steady-state airspeed based on the airspeed mathematical model, and obtains the tilt angle limit parameter introduced into attitude control based on the correspondence; calculates the transient airspeed based on the airspeed mathematical model, attitude measurement, and acceleration measurement, and executes the corresponding airspeed protection procedure based on the detection result of the transient airspeed. This invention realizes an airspeed envelope protection scheme that utilizes dynamic principles and does not rely on traditional airspeed sensor observations, effectively saving hardware and maintenance costs and ensuring flight safety. Attached Figure Description

[0041] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0042] Figure 1 This is the first flowchart of the multi-rotor airspeed envelope protection method of the present invention;

[0043] Figure 2 This is the second flowchart of the multi-rotor airspeed envelope protection method of the present invention;

[0044] Figure 3 This is the third flowchart of the multi-rotor airspeed envelope protection method of the present invention;

[0045] Figure 4 This is the fourth flowchart of the multi-rotor airspeed envelope protection method of the present invention;

[0046] Figure 5 This is the fifth flowchart of the multi-rotor airspeed envelope protection method of the present invention;

[0047] Figure 6 This is the sixth flowchart of the multi-rotor airspeed envelope protection method of the present invention;

[0048] Figure 7This is the seventh flowchart of the multi-rotor airspeed envelope protection method of the present invention. Detailed Implementation

[0049] It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0050] In the following description, the use of suffixes such as "module," "part," or "unit" to denote elements is solely for the purpose of illustrative purposes and has no specific meaning in itself. Therefore, "module," "part," or "unit" may be used interchangeably.

[0051] Figure 1 This is a flowchart of the multi-rotor airspeed envelope protection method of the present invention. This embodiment proposes a multi-rotor airspeed envelope protection method, which includes:

[0052] S1. Establishing a mathematical model of airspeed Where m is mass, g is gravitational acceleration, θ is tilt angle, V is airspeed, and k1(θ), k2(θ), and k3(θ) are the first, second, and third order drag coefficient functions, respectively.

[0053] S2. Determine the correspondence between the maximum tilt angle and the maximum steady-state airspeed based on the airspeed mathematical model, and obtain the tilt angle limit parameter introduced into attitude control based on the correspondence.

[0054] S3. Calculate the transient airspeed based on the airspeed mathematical model, attitude measurement, and acceleration measurement, and execute the corresponding airspeed protection procedure based on the detection result of the transient airspeed.

[0055] In this embodiment, the coordinate system is first defined as follows: Ground coordinate system O E -X E Y E Z E Body coordinate system O B -X B Y B Z B The horizontal coordinate system (custom coordinate system) of the aircraft body is O-XYZ, where the origin O is set at the center of mass of the aircraft body, OX is in the plane of symmetry of the aircraft body and points horizontally forward of the aircraft body, OZ is vertically downward, and OY follows the right-hand rule and points horizontally to the right side of the aircraft body.

[0056] In this embodiment, the notation is defined as follows: a is the acceleration along the center of mass, g is the acceleration due to gravity, V is the airspeed, and V0 is the velocity of air. wind For the incoming airflow speed, V gndLet θ be the ground speed, θ be the horizontal tilt angle of the fuselage, and optionally, for longitudinal motion, θ be the pitch angle, and k1(θ), k2(θ), and k3(θ) be the first, second, and third order drag coefficient functions dynamically related to the horizontal tilt angle, respectively.

[0057] In this embodiment, the subscripts x, y, z of the above physical quantities are defined as representing the three-axis projection or components of the corresponding body horizontal coordinate system, and the subscript x b ,y b ,z b (x e ,y e ,z e ) represents the three-axis projection or components in the corresponding body coordinate system (i.e., ground coordinate system).

[0058] Alternatively, please refer to Figure 2 The establishment of the airspeed mathematical model includes:

[0059] S11. Establish the mathematical model for airspeed calculation. x =-(k1(θ)·V+k2(θ)·V 2 +k3(θ)·V 3 )+mg tanθ, where a x For acceleration;

[0060] S12. Determine the kinematic constraints satisfied by the longitudinal motion:

[0061]

[0062] Among them, V wind For the incoming airflow speed, V gnd For ground speed.

[0063] Alternatively, please refer to Figure 3 The establishment of the airspeed mathematical model also includes:

[0064] S13. For stable flow fields such as calm winds, steady winds, and gently changing gusts, take...

[0065] S14. For non-stationary flow fields such as gusts, due to energy attenuation, the wind speed at the end of the gust can be considered to have...

[0066] Attenuation characteristics, i.e. Therefore, its steady state takes

[0067] S15. By combining the airspeed calculation mathematical model with the kinematic constraints satisfied by the longitudinal motion, the airspeed mathematical model is established.

[0068] Alternatively, please refer to Figure 4The step of determining the correspondence between the maximum tilt angle and the maximum steady-state airspeed based on the airspeed mathematical model, and obtaining the tilt angle limit parameter introduced into attitude control based on the correspondence, includes:

[0069] S21, Definition At that time, V, determined by the aforementioned airspeed mathematical model, is the equilibrium airspeed V at a given tilt angle θ. e (θ), where each tilt angle θ has a unique corresponding equilibrium airspeed V. e For a given tilt angle θ, the following relationship exists:

[0070] When V < V e When (θ),

[0071] When V > V e When (θ),

[0072] S22, combined with balanced airspeed V e (θ) represents the stable equilibrium state of the airspeed V at an inclination angle θ, where the inclination angle θ and the equilibrium airspeed V are related. e There is a one-to-one mapping relationship between (θ), that is, the larger the tilt angle θ, the higher the equilibrium airspeed V. e The larger (θ) is.

[0073] S23. Based on this mapping relationship, the maximum tilt angle θ is limited by a control algorithm. max At that time, the steady-state airspeed is determined to be limited to the maximum value V. e_max .

[0074] Therefore, this embodiment can determine the tilt angle θ and the equilibrium airspeed V. e The mapping relationship between (θ).

[0075] Optionally, in this embodiment, in response to gust interference, the transient airspeed V may briefly exceed the steady-state airspeed V. e (θ), however, as time goes on, the gust energy decays, and the airspeed steady state will still return to V. e (θ). Therefore, in this embodiment, the effect of gusts on airspeed is treated as a transient disturbance, while the steady state still satisfies the dynamic model shown in the above airspeed mathematical model.

[0076] Alternatively, please refer to Figure 5 The step of determining the correspondence between the maximum tilt angle and the maximum steady-state airspeed based on the airspeed mathematical model, and obtaining the tilt angle limit parameter introduced into attitude control based on the correspondence, further includes:

[0077] S24. Through flight tests, different tilt angle limits θ are set each time. MAX Using a step size of 1 degree, iterate through all possible tilt angle constraints θ. MAXScope of application;

[0078] S25. Determine the maximum tilt angle θ based on the ergodic data from the flight test. max With maximum steady-state airspeed V e_max A table showing the numerical correspondence between them.

[0079] In this embodiment, regarding tilt angle limitation protection, firstly, through analysis of the airspeed mathematical model, it can be seen that the tilt angle θ is related to the steady-state airspeed V. e There is a one-to-one mapping relationship between (θ) and (θ). Under the constraint of the maximum tilt angle θ max Under this premise, the maximum steady-state airspeed of the multirotor is also limited to V. e_max Therefore, this embodiment can introduce tilt angle limitation in attitude control, and limit the tilt angle through algorithm, thereby achieving the purpose of limiting steady-state airspeed.

[0080] Optionally, in this embodiment, a tilt angle limit is introduced in the attitude control, and the limit value can be set by parameters.

[0081] Alternatively, please refer to Figure 6 The step of determining the correspondence between the maximum tilt angle and the maximum steady-state airspeed based on the airspeed mathematical model, and obtaining the tilt angle limit parameter introduced into attitude control based on the correspondence, further includes:

[0082] S26. Given an airspeed envelope V max And with a 25% margin for gusts, determine the maximum steady-state airspeed V. e_max = (1-25%)*V max ;

[0083] S27. Determine the maximum tilt angle θ according to the numerical correspondence table. max And the maximum tilt angle θ max Set as the tilt angle limit parameter for the attitude control algorithm.

[0084] Alternatively, please refer to Figure 7 The step of calculating the transient airspeed based on the airspeed mathematical model, attitude measurement, and acceleration measurement, and executing corresponding airspeed protection procedures based on the transient airspeed detection results, includes:

[0085] S31. Detect whether the transient airspeed calculated at a frequency of 1Hz exceeds the threshold.

[0086] S32. When the transient airspeed exceeds the threshold, execute the corresponding airspeed protection procedure.

[0087] Optionally, the step of calculating the transient airspeed based on the airspeed mathematical model, attitude measurement, and acceleration measurement, and executing the corresponding airspeed protection procedure based on the transient airspeed detection result, further includes:

[0088] In k1*V max ≤V <k2*V max At that time, an alarm message is sent to the ground station, and the remote crew is required to continuously monitor the airspeed status;

[0089] In k2*V max ≤V <V max At that time, the target speed is actively reduced and the tilt angle is decreased through the flight controller until the airspeed is lower than k1*V. max ;

[0090] When V≥V max At that time, the aircraft is controlled by the flight controller to decelerate to a hovering state and begin returning to base or landing as soon as possible;

[0091] Among them, k1 <k2;

[0092] Optionally, in this embodiment, the value range of k1 is 0.5 to 0.8, and the value range of k2 is 0.7 to 0.9.

[0093] The beneficial effects of this embodiment are as follows: An airspeed mathematical model is established; the correspondence between the maximum tilt angle and the maximum steady-state airspeed is determined based on the airspeed mathematical model, and the tilt angle limit parameter introduced into attitude control is obtained based on the correspondence; the transient airspeed is calculated based on the airspeed mathematical model, attitude measurement, and acceleration measurement, and the corresponding airspeed protection procedure is executed based on the detection result of the transient airspeed. This achieves an airspeed envelope protection scheme that utilizes dynamic principles and does not rely on traditional airspeed sensor observations, effectively saving hardware and maintenance costs and ensuring flight safety.

[0094] Based on the above embodiments, the present invention also proposes a multi-rotor airspeed envelope protection device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the computer program is executed by the processor, it implements the steps of the multi-rotor airspeed envelope protection method as described in any of the above embodiments.

[0095] It should be noted that the above-described device embodiments and method embodiments belong to the same concept. The specific implementation process can be found in the method embodiments, and the technical features in the method embodiments are also applicable to the device embodiments, which will not be repeated here.

[0096] Based on the above embodiments, the present invention also proposes a computer-readable storage medium storing a multi-rotor airspeed envelope protection program, which, when executed by a processor, implements the steps of the multi-rotor airspeed envelope protection method as described in any of the above claims.

[0097] It should be noted that the above-described medium embodiments and method embodiments belong to the same concept. The specific implementation process can be found in the method embodiments, and the technical features in the method embodiments are also applicable to the medium embodiments, which will not be repeated here.

[0098] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0099] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0100] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this 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. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes several instructions to cause a terminal (which may 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.

[0101] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for protecting the airspeed envelope of a multi-rotor aircraft, characterized in that, The method includes: Establishing a mathematical model of airspeed Where m is mass, g is gravitational acceleration, θ is tilt angle, V is airspeed, and k1(θ), k2(θ), and k3(θ) are the first, second, and third order drag coefficient functions, respectively. The correspondence between the maximum tilt angle and the maximum steady-state airspeed is determined based on the airspeed mathematical model, and the tilt angle limit parameter introduced into attitude control is obtained based on the correspondence. The transient airspeed is calculated based on the airspeed mathematical model, attitude measurement, and acceleration measurement, and the corresponding airspeed protection procedure is executed based on the detection result of the transient airspeed. in, Through flight tests, different tilt angle limits θ were set each time. MAX Using a step size of 1 degree, iterate through all possible tilt angle constraints θ. MAX Scope of application; The maximum tilt angle θ was determined based on the ergonomic data from the flight tests. max With maximum steady-state airspeed V e_max A table showing the numerical correspondence between them; The maximum tilt angle θ is determined based on the numerical correspondence table. max And the maximum tilt angle θ max Set as the tilt angle limit parameter for the attitude control algorithm.

2. The multi-rotor airspeed envelope protection method according to claim 1, characterized in that, The establishment of the airspeed mathematical model includes: Establish a mathematical model for calculating airspeed (ma) x =-(k1(θ)·V+k2(θ)·V 2 +k3(θ)·V 3 )+mg tanθ, where a x For acceleration; Determine the kinematic constraints satisfied by the longitudinal motion: Among them, V wind For the incoming airflow speed, V gnd For ground speed.

3. The multi-rotor airspeed envelope protection method according to claim 2, characterized in that, The establishment of the airspeed mathematical model also includes: For steady flow fields with no wind, constant wind, and slowly varying gusts, take For the non-stationary flow field of gusts, steady state is taken The airspeed mathematical model is established by combining the airspeed calculation mathematical model with the kinematic constraints satisfied by the longitudinal motion.

4. The multi-rotor airspeed envelope protection method according to claim 3, characterized in that, The step of determining the correspondence between the maximum tilt angle and the maximum steady-state airspeed based on the airspeed mathematical model, and obtaining the tilt angle limit parameter introduced into attitude control based on the correspondence, includes: definition At that time, V, determined by the aforementioned airspeed mathematical model, is the equilibrium airspeed V at a given tilt angle θ. e (θ), where each tilt angle θ has a unique corresponding equilibrium airspeed V. e For a given tilt angle θ, the following relationship exists: When V < V e When (θ), When V > V e When (θ), Combined with balanced airspeed V e (θ) represents the stable equilibrium state of the airspeed V at an inclination angle θ. Determine the relationship between the inclination angle θ and the equilibrium airspeed V. e The mapping relationship between (θ); Limiting the maximum tilt angle θ through a control algorithm max At that time, the steady-state airspeed is determined to be limited to the maximum value V. e_max .

5. The multi-rotor airspeed envelope protection method according to claim 4, characterized in that, The step of determining the correspondence between the maximum tilt angle and the maximum steady-state airspeed based on the airspeed mathematical model, and obtaining the tilt angle limit parameter introduced into attitude control based on the correspondence, further includes: Given an airspeed envelope V max And with a 25% margin for gusts, determine the maximum steady-state airspeed V. e_max = (1-25%)*V max .

6. The multi-rotor airspeed envelope protection method according to claim 5, characterized in that, The transient airspeed is calculated based on the airspeed mathematical model, attitude measurement, and acceleration measurement, and the corresponding airspeed protection procedure is executed based on the transient airspeed detection result, including: Whether the transient airspeed calculated at a frequency of 1Hz exceeds the threshold; When the transient airspeed exceeds the threshold, the corresponding airspeed protection procedure is executed.

7. The multi-rotor airspeed envelope protection method according to claim 6, characterized in that, The step of calculating the transient airspeed based on the airspeed mathematical model, attitude measurement, and acceleration measurement, and executing the corresponding airspeed protection procedure based on the transient airspeed detection result, further includes: In k1*V max ≤V <k2*V max At that time, an alarm message is sent to the ground station, and the remote crew is required to continuously monitor the airspeed status; In k2*V max ≤V <V max At that time, the target speed is actively reduced and the tilt angle is decreased through the flight controller until the airspeed is lower than k1*V. max ; When V≥V max At that time, the aircraft is controlled by the flight controller to decelerate to a hovering state and begin returning to base or landing; Among them, k1 <k2。 8. A multi-rotor airspeed envelope protection device, characterized in that, The device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the multi-rotor airspeed envelope protection method as described in any one of claims 1 to 7.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a multi-rotor airspeed envelope protection program, which, when executed by a processor, implements the steps of the multi-rotor airspeed envelope protection method as described in any one of claims 1 to 7.

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