Method, device and equipment for determining level flight trim parameters of stratospheric airship and medium

Abstract

The invention provides a level flight trim parameter determination method, device and equipment for a stratospheric airship and a medium. The method comprises the steps that a steady straight line level flight equation of a nominal level flight state of the stratospheric airship is determined based on related parameters of the airship; determining an updated iteration value based on the iteration initial value, the number of iterations and an iteration calculation formula of the steady straight line level flight equation; determining an iteration residual error based on the updated iteration value, updating the number of iterations under the condition that the iteration residual error is not converged, updating an iteration initial value based on the updated iteration value, and returning and determining the updated iteration value based on the updated iteration initial value and the number of iterations until the iteration residual error is converged, substituting the newest density iteration value into the standard atmosphere model to obtain an updated level flight height; and taking the newest level flight attack angle, level flight speed and level flight height as level flight balancing parameters. According to the calculation method, the level flight balancing parameters can be determined, so that the airship flight performance envelope diagram is simply and conveniently obtained, and a reference is provided for design of a stratospheric airship flight control law.

Description

Technical Field

[0001] The invention relates to the field of aviation measurement and control technology, and in particular to a method, device, equipment and medium for determining level flight trim parameters of a stratospheric airship. Background Art

[0002] The trim of an aircraft is to find the balance point of the aircraft. Balance is the basis for the stable flight of an aircraft. Only on the basis of achieving the balance of force and torque can the flight characteristics of the aircraft be further analyzed and the flight control law be designed. Stratospheric airships have a large mass and weak control force, and generally cannot use rudders to control the pitch angle like airplanes.

[0003] When the power of the airship changes, the pitch angle of the airship changes, and the flight altitude of the airship changes accordingly. Therefore, unlike the horizontal straight flight of conventional aircraft such as airplanes, the nominal level flight state of the stratospheric airship is not a fixed-altitude flight, but a floating-altitude flight state, which requires a redesigned algorithm for trim calculation. Summary of the invention

[0004] The invention provides a method, device, equipment and medium for determining the level flight trim parameters of a stratospheric airship, so as to solve the defect in the prior art that the stratospheric airship dynamic equation is not applicable to the floating high flight state.

[0005] The present invention provides a method for determining the level flight trim parameters of a stratospheric airship, comprising the following steps: Obtain relevant parameters of the airship, and determine the steady straight-line level flight equation of the stratospheric airship in nominal level flight state based on the relevant parameters; the relevant parameters include closed system mass, airship length, airship volume, airship aerodynamic parameters, number of main propellers, and propeller thrust coefficient; Determine an iterative initial value and an iteration number of a level flight trim parameter, wherein the iterative initial value includes a first density initial value, a first angle of attack initial value of a level flight angle of attack, and a first speed initial value of a level flight speed; Based on the iteration initial value and the iteration number, and the iterative calculation formula of the steady straight-line level flight equation, an updated iteration value is determined; the updated iteration value includes a second density iteration value, a second angle of attack iteration value, and a second speed iteration value; Based on the updated iteration value, an iteration residual is determined, and when the iteration residual has not converged, the iteration number is updated, the iteration initial value is updated based on the updated iteration value, and the updated iteration value is returned to be determined based on the updated iteration initial value and the updated iteration number until the iteration residual converges, and the updated density iteration value in the latest updated iteration value is substituted into the standard atmosphere model to obtain an updated level flight altitude; The updated level flight angle of attack and the updated level flight speed in the latest updated iterative value, as well as the updated level flight altitude, are used as the level flight trim parameters.

[0006] According to a method for determining level flight trim parameters of a stratospheric airship provided by the present invention, when the iteration residual has not converged, updating the number of iterations, updating the iteration initial value based on the updated iteration value, and returning to determine the updated iteration value based on the updated iteration initial value and the updated iteration number, comprising: If the iterative residual does not converge and the number of iterations is greater than a preset iteration number threshold, an iteration failure flag is generated, and the relaxation factor in the iterative calculation formula is increased to obtain an updated iterative calculation formula; Update the number of iterations, update the iteration initial value based on the updated iteration value, and return to execute the step of determining the updated iteration value based on the updated iteration initial value and the updated number of iterations, and the updated iteration calculation formula.

[0007] According to a method for determining level flight trim parameters of a stratospheric airship provided by the present invention, the first density initial value is determined based on the closed system mass and the airship volume.

[0008] According to a method for determining level flight trim parameters of a stratospheric airship provided by the present invention, the first angle of attack initial value is determined based on a static trim pitch angle; The static trim pitch angle is determined based on the horizontal axis position and the vertical axis position of the airship's center of mass in the hull coordinate system.

[0009] According to a method for determining level flight trim parameters of a stratospheric airship provided by the present invention, the updated level flight angle of attack and the updated level flight speed in the latest updated iterative value, as well as the updated level flight altitude, are used as the level flight trim parameters, and then the method further includes: determining a first airship flight performance envelope based on the updated level flight angle of attack; determining a second airship flight performance envelope based on the updated level flight speed; Based on the updated level flight altitude, a third airship flight performance envelope is determined.

[0010] According to a method for determining the level flight trim parameters of a stratospheric airship provided by the present invention, the formula of the steady straight line level flight equation is as follows: in, is the combined thrust of the main propeller, represents the angle of attack in level flight, is the aerodynamic drag, is the aerodynamic lift, is the atmospheric density at level flight altitude, is the volume of the airship, Closed system quality, is the acceleration due to gravity, is the aerodynamic pitch moment in the flight control body coordinate system, is the moment of gravity on the body center.

[0011] The present invention also provides a device for determining the level flight trim parameters of a stratospheric airship, comprising the following units: an acquisition unit, configured to acquire relevant parameters of the airship, and determine the steady straight-line level flight equation of the stratospheric airship in a nominal level flight state based on the relevant parameters; the relevant parameters include closed system mass, airship length, airship volume, airship aerodynamic parameters, number of main propellers, and propeller thrust coefficient; A first determining unit is used to determine an iteration initial value and an iteration number of a level flight trim parameter, wherein the iteration initial value includes a first density initial value, a first angle of attack initial value of a level flight angle of attack, and a first speed initial value of a level flight speed; a second determining unit, configured to determine an updated iteration value based on the iteration initial value and the iteration number, and an iterative calculation formula of the steady straight-line level flight equation; the updated iteration value includes a second density iteration value, a second angle of attack iteration value, and a second velocity iteration value; an iteration unit, configured to determine an iteration residual based on the updated iteration value, and update the number of iterations if the iteration residual has not converged, update the iteration initial value based on the updated iteration value, return to determine the updated iteration value based on the updated iteration initial value and the updated number of iterations until the iteration residual converges, and substitute the updated density iteration value in the latest updated iteration value into the standard atmosphere model to obtain an updated level flight altitude; The level flight trim parameter determination unit is used to use the updated level flight angle of attack and the updated level flight speed in the latest updated iterative value, as well as the updated level flight altitude, as the level flight trim parameters.

[0012] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method for determining the level flight trim parameters of a stratospheric airship as described in any one of the above is implemented.

[0013] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the method for determining the level flight trim parameters of a stratospheric airship as described in any one of the above is implemented.

[0014] The present invention also provides a computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the method for determining the level flight trim parameters of a stratospheric airship as described in any one of the above is implemented.

[0015] The method, device, equipment and medium for determining the level flight trim parameters of a stratospheric airship provided by the present invention are different from conventional aircraft such as airplanes that maintain constant altitude flight through control of rudder surfaces. The control and driving ability of a stratospheric airship is relatively weak, and its nominal level flight state is usually designed as a floating altitude flight mode, that is, as the dynamic lift changes at different speeds, the flight altitude of the airship will change near the refloating equilibrium altitude. Therefore, the level flight trim equation and trim parameter calculation method of traditional aircraft are not applicable to stratospheric airships. In view of the characteristics of the nominal level flight state of stratospheric airships, the present invention reasonably simplifies the general dynamic equation of the stratospheric airship to obtain the steady-state straight-line level flight equation of the stratospheric airship. The equation is solved by an iterative method to calculate the level flight trim parameters of the airship at a given main propeller speed and static trim pitch angle. The calculation method can simply and conveniently obtain the airship flight performance envelope diagram, providing a benchmark for the design of the stratospheric airship flight control law. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 This is one of the flow charts of the method for determining the level flight trim parameters of a stratospheric airship provided by the present invention.

[0018] Figure 2 It is a schematic diagram of the longitudinal force of the stratospheric airship provided by the present invention.

[0019] Figure 3 It is a schematic diagram of the horizontal flight speed envelope of the stratospheric airship provided by the present invention.

[0020] Figure 4 It is a schematic diagram of the angle of attack envelope diagram of the stratospheric airship in level flight provided by the present invention.

[0021] Figure 5 It is a schematic diagram of the horizontal flight altitude envelope of the stratospheric airship provided by the present invention.

[0022] Figure 6 This is the second flow chart of the method for determining the level flight trim parameters of a stratospheric airship provided by the present invention.

[0023] Figure 7 The present invention is a schematic diagram of the structure of a device for determining level flight trim parameters of a stratospheric airship provided by the present invention.

[0024] Figure 8 It is a structural schematic diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] A stratospheric airship is an aircraft that relies on air buoyancy to remain suspended in the stratosphere for a long time. It has important prospects in the fields of regional atmospheric environment monitoring, high-resolution real-time surveillance, early warning and missile defense, and regional communications.

[0027] Comparative analysis and flight practice with low-altitude soft airships show that the aerodynamic coupling effect caused by the flexible effect of the inflatable bag of the stratospheric airship is not dominant, and the "rigidity assumption" can be used for flight dynamics modeling. Based on the body coordinate system, the dynamic equation based on airspeed is as follows: (1) in, , , are the mass matrix, center of mass position matrix and moment of inertia matrix; Add inertia matrix for 6x6; , are the total external force and total external moment (including gravity, buoyancy, thrust, steady and quasi-steady aerodynamic forces) acting on the airship respectively; E is the third-order unit matrix, is the speed (airspeed), is the acceleration, is the angular velocity of the airship, is the angular acceleration, and are the inertia forces and moments, which have the following forms: That is, the dynamic equations of stratospheric airships are not applicable to the floating flight state, and a new algorithm needs to be designed for balancing calculations.

[0028] Based on the above problems, the present invention provides a method for determining the level flight trim parameters of a stratospheric airship. Figure 1 FIG. 1 is one of the flow charts of the method for determining the level flight trim parameters of a stratospheric airship provided by the present invention, such as Figure 1 As shown, the method includes step 110, step 120, step 130, step 140 and step 150.

[0029] Step 110, obtaining relevant parameters of the airship, and determining the steady straight-line level flight equation of the stratospheric airship in the nominal level flight state based on the relevant parameters; the relevant parameters include closed system mass, airship length, airship volume, airship aerodynamic parameters, number of main propellers, and propeller thrust coefficient; Step 120, determining the iteration initial value and the number of iterations of the level flight trim parameters, wherein the iteration initial value includes a first density initial value, a first angle of attack initial value of the level flight angle of attack, and a first speed initial value of the level flight speed; Step 130, determining an updated iteration value based on the iteration initial value and the iteration number, and the iterative calculation formula of the steady straight-line level flight equation; the updated iteration value includes a second density iteration value, a second angle of attack iteration value, and a second speed iteration value; Step 140, determining an iteration residual based on the updated iteration value, and updating the iteration number if the iteration residual has not converged, updating the iteration initial value based on the updated iteration value, returning to determine the updated iteration value based on the updated iteration initial value and the updated iteration number until the iteration residual converges, and substituting the updated density iteration value in the latest updated iteration value into the standard atmosphere model to obtain an updated level flight altitude; Step 150: Using the updated level flight angle of attack and the updated level flight speed in the latest updated iterative value, as well as the updated level flight altitude, as the level flight trim parameters.

[0030] Specifically, the embodiment of the present invention simplifies the general dynamic equation of the airship shown in formula (1) according to the characteristics of the nominal level flight state of the stratospheric airship, and uses the iterative method to solve the simplified equation to obtain the level flight trim parameters simply and quickly.

[0031] The conditions for the stratospheric airship to achieve nominal level flight are: the yaw propeller is not actuated, the main propeller speed is fixed and there is no differential. Under the above assumptions, the nominal motion is only longitudinal motion. Figure 2 FIG. 1 is a schematic diagram of the longitudinal force of the stratospheric airship provided by the present invention, as shown in FIG. Figure 2 As shown, the equation of motion degenerates into the following force balance equation The equation for steady straight-line level flight is as follows: (2) in, is the combined thrust of the main propeller, represents the angle of attack in level flight, is the aerodynamic drag, is the aerodynamic lift, is the atmospheric density at level flight altitude, is the volume of the airship, Closed system quality, is the acceleration due to gravity, is the aerodynamic pitch moment in the flight control body coordinate system, is the moment of gravity on the body center.

[0032] The first equation in the formula reflects the "thrust-drag balance"; the second equation reflects the "lift-weight balance", where the lift includes buoyancy and aerodynamic lift; the third equation is the moment balance equation, which is the compatibility condition of the first two equations. The calculation of each force and moment in the equation is as follows: in, is the aerodynamic characteristic area, and the volume Power, The number of main propellers, is the centroid position, is the propeller thrust coefficient, which is related to the forward ratio Polynomial function of .

[0033] That is, first, obtain the relevant parameters of the airship, and based on the relevant parameters, determine the steady-state linear flight equation of the stratospheric airship in nominal level flight state. The relevant parameters include the closed system mass m, the airship length L, the airship volume 、Airship aerodynamic parameters (drag coefficient , lift coefficient , aerodynamic pitch moment coefficient ), number of main propellers and propeller thrust coefficient .

[0034] Given the main propeller speed n and the static trim pitch angle , solving the equilibrium equation group (2), we can obtain the level flight speed V, the trim angle of attack α, and the atmospheric density ρ at the level flight altitude, and then obtain the level flight altitude H from the standard atmosphere.

[0035] The equation group (2) can be numerically solved by the iterative method, and the iterative calculation formula is constructed: (3) (4) (5) (6) Where λ in formula (6) is the relaxation factor, which is usually 2. When the iteration does not converge, λ can be appropriately increased. The larger the λ, the stronger the convergence stability, but the lower the convergence efficiency.

[0036] Then determine the iteration initial value and the iteration number of the level flight trim parameter, the iteration initial value includes the first density initial value, the first attack angle initial value of the level flight angle of attack and the first speed initial value of the level flight speed.

[0037] The initial value of the iteration can be: in, represents the initial value of the first density, represents the initial value of the first angle of attack, Indicates the initial value of the first speed.

[0038] Here, the first density initial value is Based on closed system quality and airship volume Sure.

[0039] Further, based on the iteration initial value and the number of iterations, and the iterative calculation formula of the steady straight-line level flight equation, the updated iteration value is determined, wherein the updated iteration value includes a second density iteration value, a second angle of attack iteration value, and a second speed iteration value.

[0040] That is, the initial value will be iterated , and Substitute the right side of iterative calculation formulas (3) to (6) to obtain , and .

[0041] Finally, based on the updated iteration value, the iteration residual is determined, that is, the calculation and The first iteration residual between and The second iteration residual of and The third iteration residual, then, take the maximum value among the first iteration residual, the second iteration residual and the third iteration residual as the iteration residual, and determine whether the iteration residual reaches the convergence standard, and if the iteration residual has not converged, update the number of iterations, update the iteration initial value based on the updated iteration value, return and determine the updated iteration value based on the updated iteration initial value and the updated number of iterations, until the iteration residual converges, and substitute the updated density iteration value in the latest updated iteration value into the standard atmosphere model to obtain the updated level flight altitude.

[0042] It should be noted that to determine whether the iteration residual has reached the convergence standard, the iteration residual can be compared with a preset iteration threshold. When the iteration residual is less than the preset iteration threshold, it is determined that the iteration residual has reached the convergence standard. When the iteration residual is greater than or equal to the preset iteration threshold, it is determined that the iteration residual has not converged.

[0043] Further, the updated level flight angle of attack, the updated level flight speed, and the updated level flight altitude in the latest updated iteration value are used as level flight trim parameters.

[0044] It should be noted that the corresponding airship flight performance envelope diagrams can be obtained based on the updated level flight angle of attack, the updated level flight speed, and the updated level flight altitude.

[0045] The method provided in the embodiment of the present invention is different from conventional aircraft such as airplanes that maintain constant altitude flight through control surfaces. The control and driving ability of stratospheric airships is relatively weak, and their nominal level flight state is usually designed as a floating altitude flight mode, that is, as the dynamic lift changes at different speeds, the flight altitude of the airship will change near the refloating equilibrium altitude. Therefore, the level flight trim equation and trim parameter calculation method of traditional aircraft are not applicable to stratospheric airships. In view of the characteristics of the nominal level flight state of stratospheric airships, the present invention reasonably simplifies the general dynamic equation of stratospheric airships to obtain the steady-state straight-line level flight equation of stratospheric airships. The equation is solved by an iterative method to calculate the level flight trim parameters of the airship at a given main propeller speed and static trim pitch angle. The calculation method can simply and conveniently obtain the airship flight performance envelope diagram, providing a benchmark for the design of stratospheric airship flight control laws.

[0046] Based on the above embodiment, in step 140, when the iteration residual has not converged, updating the number of iterations, updating the iteration initial value based on the updated iteration value, and returning to determine the updated iteration value based on the updated iteration initial value and the updated number of iterations include: Step 141, when the iterative residual has not converged and the number of iterations is greater than a preset iteration number threshold, an iteration failure flag is generated, and the relaxation factor in the iterative calculation formula is increased to obtain an updated iterative calculation formula; Step 142, updating the number of iterations, updating the iteration initial value based on the updated iteration value, and returning to execute the step of determining the updated iteration value based on the updated iteration initial value and the updated number of iterations, and the updated iteration calculation formula.

[0047] Specifically, when the iterative residual has not converged and the number of iterations is greater than a preset iteration number threshold, an iteration failure flag is generated, and the relaxation factors in the iterative calculation formulas (3) to (6) are increased to obtain an updated iterative calculation formula.

[0048] It is understandable that when the iteration does not converge, λ can be appropriately increased. The larger λ is, the stronger the convergence stability is, but the lower the convergence efficiency is.

[0049] Then, the number of iterations is updated, that is, the number of iterations is increased by 1, and then the iteration initial value is updated based on the updated iteration value, and the execution is returned to the step of determining the updated iteration value based on the updated iteration initial value and the updated number of iterations, as well as the updated iteration calculation formula, until the iteration residual converges.

[0050] Based on the above embodiment, the initial value of the first angle of attack is determined based on the static trim pitch angle; The static trim pitch angle is determined based on the horizontal axis position and the vertical axis position of the airship's center of mass in the hull coordinate system.

[0051] Specifically, the initial value of the first angle of attack Static trim pitch angle OK, statically trim the pitch angle , that is, the equilibrium pitch angle when flying without power, the formula is as follows: in, It represents the horizontal axis position of the airship's center of mass in the airship coordinate system. Indicates the vertical axis position of the airship's center of mass in the airship's coordinate system.

[0052] Once the airship is designed, immutable, The posture-adjustable auxiliary airbag can be inflated and deflated. Balanced to an expected value close to zero. Therefore, it is generally Treated as a configurable quantity. After given, Determined by the following formula.

[0053] Based on the above embodiment, step 150 further includes: Step 151, determining a first airship flight performance envelope based on the updated level flight angle of attack; Step 152, determining a second airship flight performance envelope based on the updated level flight speed; Step 153: Determine a third airship flight performance envelope based on the updated level flight altitude.

[0054] Specifically, Figure 3 It is a schematic diagram of the horizontal flight speed envelope of the stratospheric airship provided by the present invention, Figure 4 is a schematic diagram of the angle of attack envelope of a stratospheric airship in level flight provided by the present invention, Figure 5Schematic diagram of the altitude envelope of the stratospheric airship provided by the present invention, such as Figure 3 , Figure 4 and Figure 5 As shown, that is, based on the updated level flight angle of attack, the first airship flight performance envelope is determined, then based on the updated level flight speed, the second airship flight performance envelope is determined, and finally, based on the updated level flight altitude, the third airship flight performance envelope is determined.

[0055] Based on any of the above embodiments, Figure 6 FIG. 2 is a flow chart of a method for determining the level flight trim parameters of a stratospheric airship provided by the present invention. Figure 6 As shown, the method includes: Step 1: Obtain relevant parameters of the airship, and determine the steady straight-line level flight equation of the stratospheric airship in nominal level flight state based on the relevant parameters; the relevant parameters include closed system mass, airship length, airship volume, airship aerodynamic parameters, number of main propellers and propeller thrust coefficient.

[0056] Step 2, determining the iterative initial value and the number of iterations of the level flight trim parameters, the iterative initial value including the first density initial value, the first angle of attack initial value of the level flight attack angle, and the first speed initial value of the level flight speed. The first density initial value is determined based on the mass of the closed system and the volume of the airship. The first angle of attack initial value is determined based on the static trim pitch angle, and the static trim pitch angle is determined based on the horizontal axis position and the vertical axis position of the airship mass center in the hull coordinate system.

[0057] Step three, based on the iteration initial value and the number of iterations, and the iterative calculation formula of the steady straight-line level flight equation, determine the updated iteration value, where the updated iteration value includes the second density iteration value, the second angle of attack iteration value and the second speed iteration value.

[0058] Step 4: determine the iteration residual based on the updated iteration value, and generate an iteration failure flag when the iteration residual has not converged and the number of iterations is greater than the preset iteration number threshold, and increase the relaxation factor in the iteration calculation formula to obtain the updated iteration calculation formula; update the number of iterations, update the iteration initial value based on the updated iteration value, return to execute the step of determining the updated iteration value based on the updated iteration initial value and the updated number of iterations, and the updated iteration calculation formula, until the iteration residual converges, and substitute the updated density iteration value in the latest updated iteration value into the standard atmosphere model to obtain the updated level flight altitude.

[0059] Step 5: Use the updated level flight angle of attack, updated level flight speed, and updated level flight altitude in the latest updated iteration value as level flight trim parameters.

[0060] Step six, based on the updated level flight angle of attack, determine the first airship flight performance envelope, then based on the updated level flight speed, determine the second airship flight performance envelope, and finally, based on the updated level flight altitude, determine the third airship flight performance envelope.

[0061] The method provided in the embodiment of the present invention is mainly used for flight performance analysis and flight control of a stratospheric airship. Its function is to calculate the level flight speed, trim angle of attack and level flight altitude of the airship in nominal level flight under a given main propeller speed and static trim pitch angle, and to draw a flight performance envelope diagram of the airship.

[0062] The device for determining the level flight trim parameters of a stratospheric airship provided by the present invention is described below. The device for determining the level flight trim parameters of a stratospheric airship described below and the method for determining the level flight trim parameters of a stratospheric airship described above can be referred to each other.

[0063] Based on any of the above embodiments, the present invention provides a device for determining level flight trim parameters of a stratospheric airship, Figure 7 FIG. 1 is a schematic diagram of the structure of the device for determining the level flight trim parameters of a stratospheric airship provided by the present invention. Figure 7 As shown, the device comprises: The acquisition unit 710 is used to acquire relevant parameters of the airship, and determine the steady straight-line level flight equation of the stratospheric airship in the nominal level flight state based on the relevant parameters; the relevant parameters include closed system mass, airship length, airship volume, airship aerodynamic parameters, number of main propellers and propeller thrust coefficient; A first determining unit 720 is used to determine an iteration initial value and an iteration number of a level flight trim parameter, wherein the iteration initial value includes a first density initial value, a first angle of attack initial value of a level flight angle of attack, and a first speed initial value of a level flight speed; A second determining unit 730 is configured to determine an updated iteration value based on the iteration initial value and the iteration number, and an iterative calculation formula of the steady straight-line-level flight equation; the updated iteration value includes a second density iteration value, a second angle of attack iteration value, and a second speed iteration value; The iteration unit 740 is configured to determine an iteration residual based on the updated iteration value, and if the iteration residual has not converged, update the iteration number, update the iteration initial value based on the updated iteration value, return to determine the updated iteration value based on the updated iteration initial value and the updated iteration number, until the iteration residual converges, and substitute the updated density iteration value in the latest updated iteration value into the standard atmosphere model to obtain an updated level flight altitude; The level flight trim parameter determination unit 750 is configured to use the updated level flight angle of attack and the updated level flight speed in the latest updated iterative value, as well as the updated level flight altitude, as the level flight trim parameters.

[0064] The device provided by the embodiment of the present invention is different from conventional aircraft such as airplanes that maintain constant altitude flight through control surfaces. The control and driving ability of stratospheric airships is relatively weak, and their nominal level flight state is usually designed as a floating altitude flight mode, that is, as the dynamic lift changes at different speeds, the flight altitude of the airship will change near the refloating equilibrium altitude. Therefore, the level flight trim equation and trim parameter calculation method of traditional aircraft are not applicable to stratospheric airships. In view of the characteristics of the nominal level flight state of stratospheric airships, the present invention reasonably simplifies the general dynamic equation of stratospheric airships to obtain the steady-state straight-line level flight equation of stratospheric airships. The equation is solved by an iterative method to calculate the level flight trim parameters of the airship at a given main propeller speed and static trim pitch angle. The calculation method can simply and conveniently obtain the airship flight performance envelope diagram, providing a benchmark for the design of stratospheric airship flight control laws.

[0065] Based on any of the above embodiments, the iteration unit 740 is specifically configured to: If the iterative residual does not converge and the number of iterations is greater than a preset iteration number threshold, an iteration failure flag is generated, and the relaxation factor in the iterative calculation formula is increased to obtain an updated iterative calculation formula; Update the number of iterations, update the iteration initial value based on the updated iteration value, and return to execute the step of determining the updated iteration value based on the updated iteration initial value and the updated number of iterations, and the updated iteration calculation formula.

[0066] Based on any of the above embodiments, the first initial density value is determined based on the closed system mass and the airship volume.

[0067] Based on any of the above embodiments, the initial value of the first angle of attack is determined based on the static trim pitch angle; The static trim pitch angle is determined based on the horizontal axis position and the vertical axis position of the airship's center of mass in the hull coordinate system.

[0068] Based on any of the above embodiments, it further includes a line envelope drawing unit, and the line envelope drawing unit is specifically used to: determining a first airship flight performance envelope based on the updated level flight angle of attack; determining a second airship flight performance envelope based on the updated level flight speed; Based on the updated level flight altitude, a third airship flight performance envelope is determined.

[0069] Based on any of the above embodiments, the formula of the steady straight-line level flight equation is as follows: in, is the combined thrust of the main propeller, represents the angle of attack in level flight, is the aerodynamic drag, is the aerodynamic lift, is the atmospheric density at level flight altitude, is the volume of the airship, Closed system quality, is the acceleration due to gravity, is the aerodynamic pitch moment in the flight control body coordinate system, is the moment of gravity on the body center.

[0070] Figure 8 is a schematic diagram of the structure of the electronic device provided by the present invention, such as Figure 8 As shown, the electronic device may include: a processor 810, a communication interface 820, a memory 830 and a communication bus 840, wherein the processor 810, the communication interface 820 and the memory 830 communicate with each other through the communication bus 840. The processor 810 may call the logic instructions in the memory 830 to execute the method for determining the level flight trim parameters of the stratospheric airship, the method comprising: obtaining relevant parameters of the airship, and determining the steady straight line level flight equation of the nominal level flight state of the stratospheric airship based on the relevant parameters; the relevant parameters include the mass of the closed system, the length of the airship, the volume of the airship, the aerodynamic parameters of the airship, the number of main propellers and the propeller thrust coefficient; determining the iterative initial value and the number of iterations of the level flight trim parameters, the iterative initial value including the first density initial value, the first angle of attack initial value of the level flight angle of attack and the first speed initial value of the level flight speed; based on the iterative initial value and the number of iterations, and the iterative calculation formula of the steady straight line level flight equation Formula, determine the updated iteration value; the updated iteration value includes a second density iteration value, a second angle of attack iteration value and a second speed iteration value; based on the updated iteration value, determine the iteration residual, and if the iteration residual has not converged, update the number of iterations, update the iteration initial value based on the updated iteration value, return to determine the updated iteration value based on the updated iteration initial value and the updated number of iterations, until the iteration residual converges, and substitute the updated density iteration value in the latest updated iteration value into the standard atmosphere model to obtain an updated level flight altitude; use the updated level flight angle of attack and the updated level flight speed in the latest updated iteration value, as well as the updated level flight altitude, as the level flight trim parameters.

[0071] In addition, the logic instructions in the above-mentioned memory 830 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0072] On the other hand, the present invention further provides a computer program product, the computer program product includes a computer program, the computer program can be stored on a non-transitory computer-readable storage medium, when the computer program is executed by a processor, the computer can execute the method for determining the level flight trim parameters of the stratospheric airship provided by the above methods, the method comprising: obtaining relevant parameters of the airship, and based on the relevant parameters, determining the steady-state straight-line level flight equation of the nominal level flight state of the stratospheric airship; the relevant parameters include the mass of the closed system, the length of the airship, the volume of the airship, the aerodynamic parameters of the airship, the number of main propellers and the propeller thrust coefficient; determining the iterative initial value and the number of iterations of the level flight trim parameters, the iterative initial value including the first density initial value, the first angle of attack initial value of the level flight angle of attack and the first speed initial value of the level flight speed; based on The iteration initial value and the iteration number, as well as the iterative calculation formula of the steady straight line level flight equation, determine the updated iteration value; the updated iteration value includes a second density iteration value, a second angle of attack iteration value and a second speed iteration value; based on the updated iteration value, determine the iteration residual, and if the iteration residual has not converged, update the iteration number, update the iteration initial value based on the updated iteration value, return to determine the updated iteration value based on the updated iteration initial value and the updated number of iterations, until the iteration residual converges, and substitute the updated density iteration value in the latest updated iteration value into the standard atmosphere model to obtain an updated level flight altitude; the updated level flight angle of attack and the updated level flight speed in the latest updated iteration value, as well as the updated level flight altitude, are used as the level flight trim parameters.

[0073] On the other hand, the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, which is implemented when the computer program is executed by a processor to execute the method for determining the level flight trim parameters of the stratospheric airship provided by the above methods, the method comprising: obtaining relevant parameters of the airship, and determining the steady-state straight-line level flight equation of the stratospheric airship in the nominal level flight state based on the relevant parameters; the relevant parameters include the mass of the closed system, the length of the airship, the volume of the airship, the aerodynamic parameters of the airship, the number of main propellers and the propeller thrust coefficient; determining the iteration initial value and the number of iterations of the level flight trim parameters, the iteration initial value including the first density initial value, the first angle of attack initial value of the level flight angle of attack and the first speed initial value of the level flight speed; based on the iteration initial value and the number of iterations, and the iterative calculation formula of the steady straight line level flight equation, to determine the updated iteration value; the updated iteration value includes a second density iteration value, a second angle of attack iteration value and a second speed iteration value; based on the updated iteration value, the iteration residual is determined, and when the iteration residual has not converged, the number of iterations is updated, the iteration initial value is updated based on the updated iteration value, and the updated iteration value is returned based on the updated iteration initial value and the updated number of iterations until the iteration residual converges, and the updated density iteration value in the latest updated iteration value is substituted into the standard atmosphere model to obtain an updated level flight altitude; the updated level flight angle of attack and the updated level flight speed in the latest updated iteration value, as well as the updated level flight altitude, are used as the level flight trim parameters.

[0074] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0075] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining the level flight trim parameters of a stratospheric airship, characterized in that: include: Obtain relevant parameters of the airship, and determine the steady straight-line level flight equation of the stratospheric airship in nominal level flight state based on the relevant parameters; the relevant parameters include closed system mass, airship length, airship volume, airship aerodynamic parameters, number of main propellers, and propeller thrust coefficient; Determine an iterative initial value and an iteration number of a level flight trim parameter, wherein the iterative initial value includes a first density initial value, a first angle of attack initial value of a level flight angle of attack, and a first speed initial value of a level flight speed; Determining an updated iteration value based on the iteration initial value and the iteration number, and the iterative calculation formula of the steady straight-line level flight equation; The updated iteration values ​​include a second density iteration value, a second angle of attack iteration value, and a second speed iteration value; Based on the updated iteration value, an iteration residual is determined, and when the iteration residual has not converged, the iteration number is updated, the iteration initial value is updated based on the updated iteration value, and the updated iteration value is returned to be determined based on the updated iteration initial value and the updated iteration number until the iteration residual converges, and the updated density iteration value in the latest updated iteration value is substituted into the standard atmosphere model to obtain an updated level flight altitude; The updated level flight angle of attack and the updated level flight speed in the latest updated iterative value, as well as the updated level flight altitude, are used as the level flight trim parameters.

2. The method for determining the level flight trim parameters of a stratospheric airship according to claim 1, characterized in that: When the iteration residual has not converged, updating the number of iterations, updating the iteration initial value based on the updated iteration value, and returning to determine the updated iteration value based on the updated iteration initial value and the updated number of iterations, comprises: If the iterative residual does not converge and the number of iterations is greater than a preset iteration number threshold, an iteration failure flag is generated, and the relaxation factor in the iterative calculation formula is increased to obtain an updated iterative calculation formula; Update the number of iterations, update the iteration initial value based on the updated iteration value, and return to execute the step of determining the updated iteration value based on the updated iteration initial value and the updated number of iterations, and the updated iteration calculation formula.

3. The method for determining the level flight trim parameters of a stratospheric airship according to claim 1, characterized in that: The first density initial value is determined based on the closed system mass and the airship volume.

4. The method for determining the level flight trim parameters of a stratospheric airship according to any one of claims 1 to 3, characterized in that: The initial value of the first angle of attack is determined based on the static trim pitch angle; The static trim pitch angle is determined based on the horizontal axis position and the vertical axis position of the airship's center of mass in the hull coordinate system.

5. The method for determining the level flight trim parameters of a stratospheric airship according to any one of claims 1 to 3, characterized in that: The updated level flight angle of attack and the updated level flight speed in the latest updated iterative value, as well as the updated level flight altitude, are used as the level flight trim parameters, and then the following further comprises: determining a first airship flight performance envelope based on the updated level flight angle of attack; determining a second airship flight performance envelope based on the updated level flight speed; Based on the updated level flight altitude, a third airship flight performance envelope is determined.

6. The method for determining the level flight trim parameters of a stratospheric airship according to any one of claims 1 to 3, characterized in that: The formula of the steady straight-line level flight equation is as follows: in, is the combined thrust of the main propeller, represents the angle of attack in level flight, is the aerodynamic drag, is the aerodynamic lift, is the atmospheric density at level flight altitude, is the volume of the airship, Closed system quality, is the acceleration due to gravity, is the aerodynamic pitch moment in the flight control body coordinate system, is the moment of gravity on the body center.

7. A device for determining the level flight trim parameters of a stratospheric airship, characterized in that: include: an acquisition unit, configured to acquire relevant parameters of the airship, and determine the steady straight-line level flight equation of the stratospheric airship in a nominal level flight state based on the relevant parameters; the relevant parameters include closed system mass, airship length, airship volume, airship aerodynamic parameters, number of main propellers, and propeller thrust coefficient; A first determining unit is used to determine an iteration initial value and an iteration number of a level flight trim parameter, wherein the iteration initial value includes a first density initial value, a first angle of attack initial value of a level flight angle of attack, and a first speed initial value of a level flight speed; A second determining unit is used to determine an updated iteration value based on the iteration initial value and the iteration number, and an iterative calculation formula of the steady straight-line level flight equation; The updated iteration values ​​include a second density iteration value, a second angle of attack iteration value, and a second speed iteration value; an iteration unit, configured to determine an iteration residual based on the updated iteration value, and update the number of iterations if the iteration residual has not converged, update the iteration initial value based on the updated iteration value, return to determine the updated iteration value based on the updated iteration initial value and the updated number of iterations until the iteration residual converges, and substitute the updated density iteration value in the latest updated iteration value into the standard atmosphere model to obtain an updated level flight altitude; The level flight trim parameter determination unit is used to use the updated level flight angle of attack and the updated level flight speed in the latest updated iterative value, as well as the updated level flight altitude, as the level flight trim parameters.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the method for determining the level flight trim parameters of the stratospheric airship according to any one of claims 1 to 6 is implemented.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for determining the level flight trim parameters of a stratospheric airship according to any one of claims 1 to 6 is implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the method for determining the level flight trim parameters of a stratospheric airship according to any one of claims 1 to 6 is implemented.

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