Expected air flow angle instruction real-time calculation method and device

Abstract

The present invention relates to a new generation of information technology, and discloses a method and device for real-time calculation of expected airflow angle instructions to improve the calculation efficiency and thus enhance the flight performance of an aircraft. The method includes: converting the complex solution process of a traditional multivariate quadratic function into an expected angle of attack value that can be quickly calculated through a finite number of iterations. In each angle of attack iteration process, the iteration formula is: , and the iteration is terminated when the difference between the lift coefficient value calculated in the current loop and the expected lift coefficient required for calculating the resultant force according to the orthogonal rule of the aircraft control force is less than the allowable angle of attack error, or when the number of iterations is greater than or equal to the preset maximum number of iterations.

Description

Technical Field

[0001] The present invention relates to the field of computer methods and devices based on a specific calculation model in the new generation of information technology, and particularly relates to a method and device for real-time calculation of desired airflow angle commands. Background Art

[0002] At present, with the increasing complexity of the flight missions of modern aircraft, the flight under complex conditions and the advanced aerodynamic configuration of the aircraft have put forward higher requirements for the guidance and control methods. The aircraft guidance and control is developing towards the integration of non-linear guidance and control with stronger flight performance. Therefore, in the process of converting guidance commands and attitude control commands, it is necessary to directly convert from the aerodynamic force function to the desired airflow angle command. However, at present, the aerodynamic force function is a multivariate quadratic function, and the calculation of the desired airflow angle command is large in amount and slow in calculation speed, which cannot be applied to the real-time calculation of the flight control computer system.

[0003] It can be seen that there is an urgent need for a real-time calculation method and device for the desired command of the airflow angle model with small calculation amount and fast non-linear guidance and control calculation speed to improve the flight performance of the aircraft under complex conditions.

[0004] Generally, the airflow angle includes the angle of attack, the sideslip angle, and the roll angle; among them, when the aircraft adopts the BTT (Bank To Turn) mode, the sideslip angle is generally 0. Therefore, when calculating the desired airflow angle command, only the desired angle of attack and roll angle need to be calculated. Summary of the Invention

[0005] The purpose of the present invention is to disclose a method and device for real-time calculation of desired airflow angle commands to improve the calculation efficiency and thus improve the flight performance of the aircraft.

[0006] To achieve the above object, the real-time calculation method for the desired airflow angle command disclosed by the present invention includes:

[0007] Step S1, obtaining the lateral desired control force and the normal desired control force , and calculating the desired lift coefficient required for synthesizing the force according to the calculation method of the aircraft control force orthogonal rule; the formula for the desired lift coefficient is: , where , are respectively the dynamic pressure and the reference area of the aircraft;

[0008] Step S2, performing an angle-of-attack iteration process. In each angle-of-attack iteration process, the iteration formula is: , and judging whether to terminate the iteration according to the first condition; where is the Mach number, is the number of iterations and takes the value of 0 at initialization; is the expected angle of attack value for the next iteration loop; is the expected angle of attack value for the current iteration loop. At initialization, it takes the value of 0; and are the lift coefficient and the derivative of the lift coefficient obtained according to the real-time and in the current iteration loop respectively; The first condition is that the difference between the lift coefficient value calculated in the current loop and the expected lift coefficient in step S1 is less than the allowable angle of attack error;

[0009] Step S3, after the angle of attack iteration ends, generate an expected airflow angle command output according to the expected angle of attack value calculated in the last iteration process.

[0010] Preferably, the dynamic pressure has the following calculation formula: ; where is the relationship function between the atmospheric density and the altitude, is the speed of the aircraft.

[0011] Preferably, the present invention further includes: calculating the expected velocity roll angle by the formula , and generating an expected airflow angle command output according to the calculated value.

[0012] Further, a second condition for terminating the iteration is added in step S2. The second condition is that the number of iterations is greater than or equal to the preset maximum number of iterations; wherein, after determining that the current number of iterations does not meet the first condition, then determine whether the current number of iterations meets the second condition. If the second condition is met, terminate the iteration, otherwise, continue the loop iteration; or, before determining that the current number of iterations does not meet the first condition, first determine whether the current number of iterations meets the second condition. If the second condition is met, terminate the iteration, otherwise, then determine whether to continue the loop iteration according to the result of whether the first condition is met.

[0013] To achieve the above object, the present invention discloses a device for real-time calculation of an expected airflow angle command, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the above method is implemented.

[0014] The present invention has the following beneficial effects:

[0015] Convert the complex solution process of the traditional multi - variable quadratic function into the expected angle of attack value that can be quickly calculated through a finite number of iterations, improve the solution efficiency, and enhance the real - time solution performance of the modern non - linear guidance and control integration method in the flight control computer system. The principle is simple, with strong engineering applicability, and improves the flight performance of modern aircraft.

[0016] The following will refer to the accompanying drawings to further elaborate on the present invention in detail. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings that form a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0018] Figure 1 is a schematic flow chart of a method for real - time solution of the expected command of the airflow angle model in Embodiment 1 of the present invention.

[0019] Figure 2 is a schematic mechanical diagram in Embodiment 1 of the present invention.

[0020] Figure 3 is a schematic diagram of a device for real - time solution of the expected command of the airflow angle model in Embodiment 2 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The following will elaborate on the embodiments of the present invention in detail with reference to the accompanying drawings. However, the present invention can be implemented in many different ways defined and covered by the claims.

[0022] Embodiment 1

[0023] Refer to Figure 1 , which is a schematic flow chart of a method for real - time solution of the expected command of the airflow angle model provided by the embodiment of the present invention. As Figure 1 shown, the method mainly includes the following steps:

[0024] Step 1: Obtain the expected control force input from the relative motion relationship between the aircraft and the target and the non - linear guidance and control integration algorithm , specify the allowable error of the angle of attack , and the maximum allowable number of loops .

[0025] In this step, the lift coefficient model function of the aircraft and the lift coefficient derivative model function are known. Among them, the lift coefficient of the aircraft is usually a binary function of the angle of attack and the Mach number , and the lift coefficient model function The data is obtained in advance through a pneumatic test and described in the form of a function, which can be loaded into the flight control computer in advance.

[0026] Step 2: Calculate the desired velocity inclination angle according to the desired control force and the dynamic relationship; solve the desired lift coefficient according to the calculation method of the resultant control force of the aircraft and the relationship between the aerodynamic coefficient and the aerodynamic force.

[0027] See Figure 2 , which is a schematic mechanical diagram provided by this embodiment. As Figure 2 shown, this step 2 is: Given the dynamic pressure Q of the real-time flight, the reference area S, according to the launch system Oxyz, the lateral desired control force , the normal desired control force and the dynamic relationship, calculate the desired velocity side inclination angle ; solve the desired lift coefficient according to the calculation method of the resultant control force of the aircraft and the relationship between the aerodynamic coefficient and the aerodynamic force .

[0028] Preferably, step 2 specifically includes:

[0029] Step 2.1: Based on the lateral desired control force and the normal desired control force being orthogonal to each other, forming a right-handed coordinate system with the direction of the aircraft velocity vector, and the velocity side inclination angle rotating around the velocity vector direction, the calculation method for the desired velocity side inclination angle is: .

[0030] Step 2.2: Calculate the real-time dynamic pressure Q according to the altitude and velocity of the aircraft and the relationship function between the atmospheric density and the altitude , and the calculation formula is: .

[0031] Step 2.3: According to the dynamic pressure Q of the aircraft and the reference area S, solve the desired lift coefficient required for the resultant force according to the calculation method of the orthogonal rule of the aircraft control force, and the calculation formula is: .

[0032] Step 3: Initialize the angle of attack iteration count and the desired angle of attack value. Specifically, it includes: initializing the iteration count , and setting the initial value of the desired angle of attack .

[0033] Step 4: Solve the lift coefficient and the derivative of the lift coefficient in the current iteration loop, and update the desired angle of attack value and the iteration count in the current iteration loop.

[0034] In other words, this step is: Given the real-time number during the flight of the aircraft, according to the desired angle of attack value in the current iteration loop , and the lift coefficient model function and the lift coefficient derivative model function of the aircraft, to calculate the lift coefficient in the current iteration loop and the lift coefficient derivative , and update the expected angle of attack value in the current iteration loop ; update the number of iterations .

[0035] Among them, the lift coefficient derivative function also obtains data in advance through aerodynamic tests and is described in the form of a function, and can be bound to the flight control computer in advance.

[0036] Based on the above embodiments, step 4 may specifically include:

[0037] Step 4.1, given the expected angle of attack value, lift coefficient and the lift coefficient derivative in the current iteration loop. Specifically, during implementation, the and that change in real time according to the number of iterations are directly substituted into the lift coefficient function and the lift coefficient derivative function to complete the calculation.

[0038] Step 4.2, calculate the expected angle of attack value in the next iteration loop, and the calculation formula is: .

[0039] Step 4.3, update the number of iterations: .

[0040] Step 5, execute loop iteration, and determine whether the set loop determination condition is satisfied: when the difference between the expected lift coefficient and the lift coefficient value calculated in the current loop is less than the angle of attack allowable error , or the number of iterations is less than the maximum sequential loop number , go to step 4; if the above conditions are not met, go to step 6.

[0041] Step 6, end the iteration, and output the latest angle of attack iteration value as the expected angle of attack command.

[0042] In summary, the method for real-time calculation of the expected airflow angle provided in this embodiment, according to the orthogonal relationship between the lateral force and the normal force, first calculates the velocity roll angle; then, according to the quadratic function relationship between the aerodynamic coefficient model and the angle of attack, performs iterative calculation through the optimal gradient descent method, and reasonably sets the qualified condition for the iterative calculation of the expected angle of attack value, so as to solve the problems of large computational amount and slow calculation speed for the inverse solution of the airflow angle command from the aerodynamic coefficient function, optimize the calculation efficiency of the airflow angle, and improve the control performance of the aircraft.

[0043] Embodiment 2

[0044] Corresponding to the above-mentioned Embodiment 1, this embodiment discloses a device for real-time calculation of expected airflow angle instructions (or referred to as "device for real-time calculation of expected instructions of airflow angle model", the so-called airflow angle model is the logical architecture used for calculating expected airflow angle instructions, which will not be elaborated hereinafter), including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the following method is implemented, and this method at least includes:

[0045] Step S1, obtain the expected lateral control force and the expected normal control force , and calculate the expected lift coefficient required for the resultant force according to the calculation method of the orthogonal rule of aircraft control forces; the expected lift coefficient has the following calculation formula: , where , are respectively the dynamic pressure and reference area of the aircraft.

[0046] Step S2, perform the angle of attack iteration process. In each angle of attack iteration process, the iteration formula is: , and determine whether to terminate the iteration according to the first condition; where is the Mach number, is the number of iterations and takes the value of 0 during initialization; is the expected angle of attack value in the next iteration loop; is the expected angle of attack value in the current iteration loop. During initialization, takes the value of 0; , are respectively the lift coefficient and the derivative of the lift coefficient obtained according to the real-time and in the current iteration loop; the first condition is that the difference between the lift coefficient value calculated in the current loop and the expected lift coefficient in Step S1 is less than the allowable angle of attack error.

[0047] Step S3, after the angle of attack iteration ends, generate an expected airflow angle instruction output according to the expected angle of attack value calculated in the last iteration process.

[0048] Preferably, the calculation formula of the dynamic pressure is: ; where is the relationship function of atmospheric density and altitude, is the speed of the aircraft.

[0049] Preferably, this embodiment further includes: calculating the expected velocity sideslip angle with the formula , and generating an expected airflow angle instruction output according to the calculated value.

[0050] Further, a second condition for terminating the iteration is added in the step S2. The second condition is that the number of iterations is greater than or equal to a preset maximum number of iterations. Among them, after determining that the current number of iterations does not meet the first condition, it is then determined whether the current number of iterations meets the second condition. If the second condition is met, the iteration is terminated; otherwise, the loop iteration continues. Or, before determining that the current number of iterations does not meet the first condition, it is first determined whether the current number of iterations meets the second condition. If the second condition is met, the iteration is terminated; otherwise, it is further determined whether to continue the loop iteration based on the result of whether the first condition is met. Thereby, the combination of the number of iterations and the accuracy further ensures that the algorithm converges during the solution calculation with a limited number of times, and can prevent the situation of too many solution calculation times of the algorithm caused by unreasonable setting of the allowable error, ensuring the real-time performance of the algorithm. In extremely rare cases, if the number of iterations meets the termination iteration condition but the error range does not conform yet, although the control accuracy will be affected during the single-group loop iteration process in such cases (a group is a series of loop iteration processes for calculating an expected angle of attack value once), in practical applications, a slight decrease in control accuracy for a few times will not have a great impact on the overall situation compared to the huge series of group loop iteration processes.

[0051] See Figure 3 , which is a schematic diagram of a device for real-time solution of the expected command of the airflow angle model provided in this embodiment. Figure 3 The device for real-time solution of the expected command of the airflow angle model shown is only an example, and should not bring any restrictions to the functions and usage scope of the embodiments of the present invention.

[0052] As Figure 3 shown, the device for real-time solution of the expected command of the airflow angle model mainly includes:

[0053] A navigation module, which is used to calculate information such as the position and speed of the aircraft, and is used for guidance command solution and Mach number acquisition.

[0054] A guidance module, which is used to store target information and aircraft characteristic information, and calculates the expected lateral force and expected normal force according to the relative motion relationship between the aircraft and the target and the guidance control law.

[0055] An aerodynamic force solution module, which is used to store the aerodynamic force model function and calculates the aerodynamic force coefficient in real time according to variables such as the real-time angle of attack and Mach number.

[0056] An airflow angle solution module, which is used to calculate the expected airflow angle in real time according to the expected lateral force and expected normal force calculated by the guidance command and the current Mach number.

[0057] The data interaction logic of the above-mentioned functional modules refers to the above steps and will not be elaborated here.

[0058] In summary, the real-time solution methods and devices for the desired airflow angle commands respectively disclosed in the above two embodiments of the present invention convert the complex solution process of traditional multivariate quadratic functions into the desired angle of attack values that can be quickly calculated through a finite number of iterations, improving the solution efficiency, enhancing the real-time solution performance of modern integrated nonlinear guidance and control methods in the flight control computer system, with simple principles and strong engineering applicability, and improving the flight performance of modern aircraft.

[0059] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various modifications and changes can be made to the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for real-time calculation of a desired airflow angle instruction, characterized in that: include: Step S1: Obtaining the desired lateral control force and the normal expected control force , the desired lift coefficient required for the composite force is calculated according to the orthogonal law calculation method of the aircraft control force; the desired lift coefficient The calculation formula is: ,in, , are the dynamic pressure and reference area of ​​the aircraft respectively; Step S2: Execute the angle of attack iteration process. In each angle of attack iteration process, the iteration formula is: , and determine whether to terminate the iteration according to the first condition; where, is the Mach number, is the number of iterations, and its value is 0 at initialization; is the expected angle of attack value in the next iteration cycle; is the expected angle of attack value in the current iteration cycle. During initialization, The value is 0; , According to the real-time and The lift coefficient and lift coefficient derivative obtained; the first condition is: the difference between the lift coefficient value calculated in the current cycle and the expected lift coefficient in step S1 is less than the allowable error of the angle of attack; Step S3: after the angle of attack iteration is completed, a desired airflow angle command output is generated according to the desired angle of attack value solved in the last iteration process.

2. The method for real-time calculation of the desired airflow angle command according to claim 1, characterized in that: Dynamic Pressure The calculation formula is: ;in, is the relationship between atmospheric density and altitude, is the speed of the aircraft.

3. The method for real-time calculation of the desired airflow angle command according to claim 1, characterized in that: Also includes: By formula Calculate the desired speed roll angle , and generates the desired airflow angle command output based on the calculated value.

4. The method for real-time calculation of the desired airflow angle command according to any one of claims 1 to 3, characterized in that: In the step S2, a second condition for terminating the iteration is added, and the second condition is that the number of iterations is greater than or equal to the maximum number of iterations set in advance; wherein, after determining that the current number of iterations does not satisfy the first condition, it is then determined whether the current number of iterations satisfies the second condition. If the second condition is satisfied, the iteration is terminated, otherwise, the loop iteration is continued; or, before determining that the current number of iterations does not satisfy the first condition, it is first determined whether the current number of iterations satisfies the second condition. If the second condition is satisfied, the iteration is terminated, otherwise, whether the loop iteration is continued is determined based on the result of whether the first condition is satisfied.

5. A device for real-time calculation of a desired airflow angle instruction, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method for real-time solution of the desired airflow angle instruction described in any one of claims 1 to 4 is implemented.

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