Airplane sideslip angle resolving method

Abstract

The invention belongs to the technical field of aircraft flight control system design, and particularly relates to an aircraft sideslip angle calculation method which comprises the following steps: S1, acquiring parameters such as lateral overload and dynamic pressure; s2, constructing a relation between a sideslip angle and lateral overload; and S3, calculating the sideslip angle of the aircraft according to the calculation relation established in the step S2. According to the method, pneumatic data analysis is started, a theoretical calculation formula is deduced and converted, and a pseudo sideslip angle formula for solving the sideslip angle according to lateral overload, a large derivative of a lateral force coefficient to the sideslip angle, gravitational acceleration and vacuum velocity is obtained. A pseudo sideslip angle signal solved by the formula is introduced into a flight control law, and when an aircraft sideslip angle signal fails, the pseudo sideslip angle signal is used for replacing a sideslip angle signal measured by a sensor, so that the lateral course modal characteristic of the aircraft can be improved, a sideslip angle limiting function is realized, the flight quality is improved, and the flight safety is ensured. And meanwhile, a speed vector symbol driving instruction can be provided for an unmanned aerial vehicle control interface.

Description

Technical Field

[0001] This invention belongs to the field of aircraft flight control system design technology, specifically relating to a method for calculating aircraft sideslip angle. Background Technology

[0002] The use of fly-by-wire flight control systems can not only effectively improve the flight quality of aircraft, but also provide boundary limiting functions while ensuring aircraft maneuverability. To meet the requirements of large sideslip angle anti-deviation characteristics of aircraft, a sideslip angle limiting function is generally provided. During maneuvering, the sideslip angle and other parameters are controlled to not exceed the limit value. The sideslip angle signal is generally measured by an atmospheric sensor. However, if there is a failure in the product or transmission, the aircraft will lose the sense of sideslip angle signal. The flight control system cannot use the sideslip angle to calculate the control law, and the head-up display cannot provide the pilot or operator with the aircraft's sideslip angle status indication. The aircraft's lateral response deteriorates, the flight quality is severely degraded, and the sideslip angle is also prone to exceed the limit. If the sideslip angle exceeds the limit too much, it will develop into a stall deviation state and then enter a spin, which may lead to excessive loss of altitude or even a serious flight accident that cannot be recovered, affecting flight safety. Summary of the Invention

[0003] Purpose of the invention: To provide a method for calculating the sideslip angle of an aircraft. This method can calculate a pseudo sideslip angle signal in real time to replace the sideslip angle signal measured by the atmospheric sensor after the aircraft sideslip angle sensor fails, ensuring the normal operation of the flight control system's lateral control, solving the problem of degraded lateral flight quality caused by sideslip angle signal failure, and the problem of flight safety affected by the failure of sideslip angle boundary limits.

[0004] Technical Solution: To achieve the above-mentioned objective, this invention proposes a method for calculating the sideslip angle of an aircraft, which is obtained by measuring lateral overload on the aircraft, and includes the following steps: Step S1: Obtain parameters such as lateral overload and dynamic pressure; Step S2: Establish the relationship between sideslip angle and lateral overload; Step S3: Calculate the aircraft sideslip angle based on the calculation relationship established in step S2.

[0005] The sideslip angle signal is fed back to the heading control branch in the control law in the flight control system to provide heading restoring torque, which enhances heading static stability. Its value is related to the lateral forces acting on the aircraft. Therefore, the core of sideslip angle signal reconstruction is the change in the lateral forces acting on the aircraft.

[0006] According to the force analysis of an aircraft, the lateral forces are generated by the wings, fuselage, vertical tail, and control surfaces. The formula for the lateral forces on an aircraft can be expressed as:

[0007] In the formula, The lateral force coefficient of the wing-body combination; The lateral force coefficient generated by rudder deflection; This is the side force coefficient generated by the aileron deflection.

[0008] contrast , , The resulting lateral force coefficients show that those generated by the ailerons and rudder are an order of magnitude smaller than those generated by the wing-body. The above formula can be simplified to:

[0009] Analysis of wind tunnel test data revealed that the side force coefficient of the wing-body combination is within the range of small to medium sideslip angles. The lateral force coefficient, which is approximately linearly related to the sideslip angle, is also linearly related to the rudder deflection. Therefore, the lateral force coefficient can also be expressed as a function of the aircraft's lateral force and rudder deflection, i.e.:

[0010] In the formula, For the lateral force derivative of the wing-body combination, The sideslip angle is then derived. The formula: In the formula It can be calculated from the formula for the lateral force coefficient. Find out, where For aircraft quality, The acceleration due to gravity is taken as 9.8 m / s². 2 , For dynamic pressure, Let be the wing area. Therefore, we can calculate... The calculation formula is shown in Formula 1:

[0011] In the formula, To measure lateral overload of the aircraft in real time; Based on the standard calculation formula (Formula 2) for the large derivative of the lateral force coefficient with respect to the sideslip angle, Formula 1 can be transformed to obtain... Formula 3 for calculation.

[0012]

[0013]

[0014] In the formula, ka = 57.3, the purpose of which is to convert radians to degrees.

[0015] Because the lateral overload is mounted on the airframe structure, its measured values ​​need to be filtered.

[0016] In summary, the pseudo sideslip angle formula calculated from lateral overload is as follows:

[0017] In the formula, ---- Pseudo sideslip angle calculated using lateral overload signal, unit: ° The aircraft's vacuum velocity can be measured in real time or pre-stored in the calculation unit and changes with the aircraft's real-time altitude and speed. The unit is m / s. ----Acceleration due to gravity, taken as 9.8 m / s² 2 ---- The largest derivative of the side force coefficient with respect to the sideslip angle, in units of 1 / rad, is pre-stored in the calculation unit and changes with the aircraft's real-time altitude and speed. ---- Real-time measurement of lateral overload on the aircraft ---- This will convert radians to degrees, with a value of 57.3. To avoid noise interference in lateral overload signal measurements, a filtering model is designed. The possible values ​​are 5 to 20.

[0018] The calculated pseudo sideslip angle signal can be used for flight control system control law calculation and head-up display.

[0019] Furthermore, step S3 includes the application of a pseudo sideslip angle signal: setting a sideslip angle fault signal SWBETAF. When SWBETAF=0, the flight control system outputs the sideslip angle signal measured by the atmospheric sensor; when SWBETAF=1, the flight control system outputs the calculated pseudo sideslip angle signal.

[0020] Furthermore, the pseudo sideslip angle signal is used for lateral control law calculation in the flight control system, sideslip angle status indication in the head-up display, or velocity vector drive indication in the UAV control interface.

[0021] Furthermore, the small and medium sideslip angle range refers to the range of sideslip angles during aircraft flight that do not reach the stall deviation threshold.

[0022] Furthermore, the pseudo sideslip angle signal calculated by this invention can be used for control law calculation in flight control systems and for head-up display.

[0023] Technical Effects: This invention starts with aerodynamic data analysis, deriving and transforming theoretical calculation formulas to obtain a pseudo-slip angle formula based on lateral overload, the large derivative of the lateral force coefficient with respect to the sideslip angle, gravitational acceleration, and vacuum velocity. Introducing the pseudo-slip angle signal calculated by this formula into the flight control law allows the pseudo-slip angle signal to replace the sensor-measured sideslip angle signal when the aircraft's sideslip angle signal fails. This improves the aircraft's lateral modal characteristics and enables sideslip angle limiting, thereby enhancing flight quality and ensuring flight safety. Simultaneously, it can also provide velocity vector drive indicators for the UAV control interface. Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating the principle and application of sideslip angle calculation. Figure 2 A comparison chart showing the measured sideslip angle and the calculated sideslip angle from flight data parameters. Detailed Implementation

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings or specific implementation examples. It should be noted that some (but not all) of the disclosed examples are shown in the drawings. In fact, many different examples can be described, and these examples should not be construed as limited to the examples set forth herein. Rather, these examples are described to better demonstrate the positive effects of the present invention, and all aspects not detailed herein are considered to be well-known or conventional techniques in the art.

[0026] See appendix Figure 1 , 2 The sideslip angle signal is fed back to the rudder channel in the flight control system to provide heading recovery torque, which enhances heading static stability. Its value is related to the lateral forces acting on the aircraft. Therefore, the core of sideslip angle signal reconstruction is the change in the lateral forces acting on the aircraft.

[0027] According to the force decomposition of an aircraft, the lateral forces are generated by the wings, fuselage, vertical tail, and control surfaces. The formula for the lateral forces on an aircraft can be expressed as:

[0028] In the formula, The lateral force coefficient of the wing-body combination; The lateral force coefficient generated by rudder deflection; This is the side force coefficient generated by the aileron deflection.

[0029] contrast , , The resulting lateral force coefficients show that those generated by the ailerons and rudder are an order of magnitude smaller than those generated by the wing-body. The above formula can be simplified to:

[0030] Data analysis revealed that within the range of small to medium sideslip angles... The lateral force coefficient of the wing-body combination is approximately linearly related to the sideslip angle, and the lateral force coefficient generated by rudder deflection is also linearly related to the rudder deflection. Therefore, the lateral force coefficient can also be expressed as a function of the aircraft's lateral force and rudder deflection, i.e.:

[0031] In the formula, For the lateral force derivative of the wing-body combination, The derivative of the lateral force generated by rudder deflection. Sideslip angle; This refers to the rudder deflection. Then, the sideslip angle is derived. The formula:

[0032] Calculation based on aircraft side force coefficient

[0033] Data obtained from aircraft measurements can be used to obtain information based on lateral overload signals. and rudder deflection angle The formula for reconstructing the sideslip angle signal is shown below:

[0034] In the formula, To measure lateral overload of the aircraft in real time, For the weight of the aircraft, For actual measurement of dynamic pressure on aircraft; This refers to the wing area of ​​the aircraft. According to the theoretical formula for calculating the major derivative, the major derivative of the side force coefficient with respect to the sideslip angle...

[0035] In the formula, ka = 57.3, the purpose of which is to convert radians to degrees.

[0036] Therefore, the above formula needs to be transformed.

[0037] In the formula, ka = 57.3, the purpose of which is to convert radians to degrees.

[0038] Because lateral overload is measured while mounted on the machine body, lateral overload requires filtering. , The possible values ​​are 5 to 20.

[0039] Figure 1The SWBETAF signal is the sideslip angle fault signal. When SWBETAF=0, it indicates that the sideslip angle signal is fault-free, and the sideslip angle output is the measured sideslip angle signal. When SWNYF=1, it indicates that the sideslip angle signal is faulty, and the sideslip angle output is the calculated pseudo sideslip angle signal. The definitions of other parameters are shown in the figure and formula. In the figure, 9.8 is the gravitational acceleration g, and 57.3 is ka in formula 4, the purpose of which is to convert radians to degrees.

[0040] The flight parameters of a certain type of fly-by-wire aircraft were analyzed by extracting pedal-assisted pulse control data. Lateral overload signals were then substituted into the patented formula to calculate the pseudo sideslip angle, which was then compared with the measured sideslip angle. Figure 2 The figure shows a comparison of the sideslip angle calculated using lateral overload after pedal-assisted pulse control of an aircraft. As can be seen from the figure, the pseudo sideslip angle signal calculated using lateral overload exhibits the same trend as the atmospheric measurement sideslip angle signal, with a small deviation. In engineering applications, it can serve as a backup signal for sideslip angle, ensuring flight safety and demonstrating significant potential for engineering applications.

[0041] The above specific embodiments or examples are only used to explain the technical solutions of the present invention and are not intended to limit the present application. Parts not described in detail are considered to be conventional technical means or common knowledge in the field. It can be understood by those skilled in the art that, based on the design concept of the present application, the technical solutions described in the foregoing embodiments can be adapted or some or all of the technical features can be equivalently replaced. These modifications, equivalent replacements, and adaptive improvements do not depart from the technical essence of the present invention and should all be covered within the protection scope of the present application.

Claims

1. A method for calculating the sideslip angle of an aircraft, obtained by measuring lateral overload on the aircraft, characterized in that, The method includes the following steps: Step S1: Obtain parameters such as lateral overload and dynamic pressure; Step S2: Establish the relationship between sideslip angle and lateral overload; Step S3: Calculate the aircraft sideslip angle based on the calculation relationship established in step S2.

2. The method for calculating the sideslip angle of an aircraft as described in claim 1, characterized in that, The sideslip angle signal is fed back to the heading control branch in the control law in the flight control system to provide heading restoring torque, which enhances heading static stability. Its value is related to the lateral forces acting on the aircraft. Therefore, the core of sideslip angle signal reconstruction is the change in the lateral forces acting on the aircraft.

3. The method for calculating the sideslip angle of an aircraft as described in claim 1, characterized in that, According to the force analysis of an aircraft, the lateral forces are generated by the wings, fuselage, vertical tail, and control surfaces; the formula for the lateral forces of an aircraft can be expressed as: In the formula, The lateral force coefficient of the wing-body combination; The lateral force coefficient generated by rudder deflection; This is the side force coefficient generated by the aileron deflection.

4. The method for calculating the sideslip angle of an aircraft as described in claim 3, characterized in that, contrast , , The lateral force coefficient generated by the ailerons and rudder is an order of magnitude smaller than that generated by the wing-body. The formula can be... Simplified as: Analysis of wind tunnel test data revealed that the side force coefficient of the wing-body combination is within the range of small to medium sideslip angles. The lateral force coefficient, which is approximately linearly related to the sideslip angle, is also linearly related to the rudder deflection. Therefore, the lateral force coefficient can also be expressed as a function of the aircraft's lateral force and rudder deflection, i.e.: In the formula, For the lateral force derivative of the wing-body combination, The sideslip angle is then derived. The formula: In the formula It can be calculated from the formula of lateral force coefficient. Find out, where For aircraft quality, The acceleration due to gravity is taken as 9.8 m / s². 2 , For dynamic pressure, Wing area; Sideslip angle The calculation formula is shown in formula (1): In the formula, To measure lateral overload of the aircraft in real time; Based on the standard calculation formula (2) for the large derivative of the lateral force coefficient with respect to the sideslip angle, formula (1) can be transformed to obtain... The calculation formula (3); In the formula, ka = 57.3, the purpose of which is to convert radians to degrees.

5. The method for calculating the sideslip angle of an aircraft as described in claim 3, characterized in that, Lateral overload is installed on the airframe structure, and its measured values ​​need to be filtered. The pseudo sideslip angle formula calculated from lateral overload is as follows: In the formula, ---- Pseudo sideslip angle calculated using lateral overload signal, unit: ° The aircraft's vacuum velocity can be measured in real time or pre-stored in the calculation unit and changes with the aircraft's real-time altitude and speed. The unit is m / s. ----Acceleration due to gravity, taken as 9.8 m / s² 2 ---- The largest derivative of the side force coefficient with respect to the sideslip angle, in units of 1 / rad, is pre-stored in the calculation unit and changes with the aircraft's real-time altitude and speed. ---- Real-time measurement of lateral overload on the aircraft ---- This will convert radians to degrees, with a value of 57.

3. To avoid noise interference in lateral overload signal measurements, a filtering model is designed. The possible values ​​are 5 to 20.

6. The method for calculating the aircraft sideslip angle according to claim 1, characterized in that, Step S3 is followed by the application of the pseudo sideslip angle signal: set the sideslip angle fault signal SWBETAF. When SWBETAF=0, the flight control system outputs the sideslip angle signal measured by the atmospheric sensor; when SWBETAF=1, the flight control system outputs the calculated pseudo sideslip angle signal.

7. The method for calculating the aircraft sideslip angle according to claim 6, characterized in that, The pseudo sideslip angle signal is used for lateral control law calculation in the flight control system, sideslip angle status indication in the head-up display, or velocity vector drive indication in the UAV control interface.

8. The method for calculating the aircraft sideslip angle according to claim 1, characterized in that, The small to medium sideslip angle range refers to the range of sideslip angles during aircraft flight that do not reach the stall deviation threshold.

9. A method for calculating the sideslip angle of an aircraft according to any one of claims 1 to 8, characterized in that, The calculated pseudo sideslip angle signal can be used for flight control system control law calculation and head-up display.

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