Longitudinal relaxed static stability aircraft without angle of attack augmentation control method, device and medium
By utilizing airborne sensors to acquire aircraft status information, a zero-angle-of-attack stabilization control strategy was constructed, which solved the safety risks and system cost issues of relaxed static stability aircraft when angle-of-attack sensors fail, and achieved improved stability and reliability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHENGDU AIRCRAFT INDUSTRY GROUP
- Filing Date
- 2023-10-13
- Publication Date
- 2026-05-12
AI Technical Summary
Existing stability augmentation control methods for relaxed static stability aircraft rely on angle-of-attack sensors, which pose safety risks in case of failure, increase system costs, and require angle-of-attack sensors.
Information on normal overload, dynamic pressure, and aircraft weight is obtained by airborne inertial sensors, fuel level sensors, and atmospheric data sensors. The control target is constructed using the roll angle target value to achieve angle-of-attack-free stabilization control, including the calculation and filtering of elevator control commands.
It achieves augmented control without angle-of-attack sensors, reduces system costs, improves system reliability, and ensures aircraft stability and safety.
Smart Images
Figure CN117348385B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of aircraft technology, specifically to a longitudinally relaxed static stability aircraft angle-of-attack stabilization control method, device, and medium. Background Technology
[0002] Static stability is the relative distance between the aircraft's aerodynamic center and its center of gravity. When the aerodynamic center is behind the center of gravity, the static stability is positive, and the aircraft is statically stable. When the aerodynamic center is in front of the center of gravity, the static stability is negative, and the aircraft is statically unstable. With relaxed static stability, the aerodynamic center is very close to the center of gravity, or even in front of it, making the aircraft weakly stable or even statically unstable.
[0003] By adopting relaxed static stability, the flight performance of the aircraft can be greatly improved. The main benefits are: (1) it is conducive to improving the maneuverability and agility of the aircraft; (2) it increases the efficiency of elevator control, which can reduce the area of the horizontal tail and reduce the structural weight; (3) the elevator control efficiency is enhanced and the trim control amount is reduced, so the trim drag is reduced; (4) it reduces the lift loss of the tail fin, or even turns it into positive lift, and improves the lift-to-drag ratio of the whole aircraft; (5) at the same time, the increase in lift-to-drag ratio and the reduction in trim drag also mean the increase in the aircraft's range and flight time.
[0004] Aircraft with relaxed static stability require stabilization control to ensure flight stability. Currently, relaxed static stability stabilization control is mainly achieved through angle-of-attack feedback control, which uses the angle of attack as a control variable and employs active control technology to achieve stable flight. For example, patent CN202210697835.1 discloses a lossless stabilization control method for a longitudinally relaxed static stability UAV. This method introduces a pitch rate signal and an angle-of-attack stabilization control strategy without stabilization trim loss into the elevator control channel to improve the UAV's dynamic characteristics. This invention is used to achieve stable control with relaxed longitudinal static stability by introducing a pitch rate signal and an angle-of-attack stabilization control strategy without stabilization trim loss into the elevator control channel to improve the UAV's dynamic characteristics.
[0005] However, such control methods have the following problems: (1) When the angle of attack sensor fails or the angle of attack signal fails, stability augmentation control cannot be performed, and the aircraft faces safety risks; (2) The aircraft must be equipped with an angle of attack sensor, which increases the system cost. Summary of the Invention
[0006] To address the shortcomings of the existing technologies, this invention proposes a longitudinally relaxed static stability aircraft angle-of-attack augmentation control method, which achieves augmentation control without angle-of-attack information.
[0007] To achieve the above-mentioned technical effects, the technical solution of this application is as follows:
[0008] A longitudinally relaxed static stability aircraft angle-of-attack-free stability enhancement control method includes the following steps:
[0009] S11. Obtain the aircraft's normal overload n through airborne inertial sensors;
[0010] S12. Obtain dynamic pressure Q through airborne atmospheric data sensors;
[0011] S13. Calculate the aircraft weight G based on the fuel level sensor information;
[0012] S14, Target value of roll angle φ c Provided by the aileron channel control law solution;
[0013] S15. Determine the stabilization control gain K. α ;
[0014] S16. Substitute the values obtained in steps S11 to S15 into formula (1) to calculate the elevator control command u, thereby controlling the aircraft to achieve angle-of-attack stabilization control:
[0015]
[0016] Where u is the elevator control command, K α The control gain, positive in sign, is obtained through parameter tuning based on the aircraft theoretical model. n represents the aircraft normal overload, which is dimensionless and measured by the onboard inertial sensor. φ c θ is the target roll angle value in degrees, Q is the dynamic pressure in Pascals, measured by the airborne atmospheric data sensor, G is the aircraft weight in Newtons, calculated by the airborne flight control computer based on fuel level sensor information, PID(θ) is the pitch angle PID control term, and PID(q) is the pitch rate PID control term.
[0017] Furthermore, the specific method for calculating the aircraft weight G based on the fuel level sensor information in step S13 is as follows:
[0018] G=G0+ρVg (2)
[0019] Where G0 is the weight of the aircraft without fuel, in Newtons; V is the fuel level sensor information, indicating the remaining fuel level, in liters; ρ is the fuel density, in kilograms per liter; and g is the acceleration due to gravity, taken as 9.8 m / s². 2 .
[0020] Furthermore, the maximum rate of change of the target roll angle is limited to 10° / s to 30° / s.
[0021] Furthermore, a filter is added to the normal overload signal, and the filter transfer function is: s is a complex variable representing the frequency in the Laplace transform domain.
[0022] Furthermore, when controlling the elevator to deflect downwards, the elevator control command is positive; when controlling the elevator to deflect upwards, the elevator control command is negative.
[0023] Furthermore, the roll angle is positive when the aircraft rolls to the right and negative when it rolls to the left.
[0024] Furthermore, normal overload is positive when it is upward and negative when it is downward.
[0025] A computer device includes a memory and a processor, wherein the memory stores a computer program and the processor executes the computer program to implement the above-described method.
[0026] A computer-readable storage medium storing a computer program, wherein a processor executes the computer program to implement the above-described method.
[0027] The advantages of this application are:
[0028] 1. The longitudinally relaxed static stability aircraft angle-of-attack augmentation control method proposed in this invention uses information such as normal overload, dynamic pressure, and aircraft weight as control variables, and constructs a normal overload control target using the roll angle target value, thereby achieving augmentation control.
[0029] 2. This invention enables aircraft with relaxed longitudinal static stability to operate without an angle-of-attack sensor, saving system costs and reducing system complexity; for aircraft with angle-of-attack sensors, this invention can increase control system redundancy and improve system reliability.
[0030] 3. For longitudinally relaxed static stability aircraft with angle of attack sensors, the stability enhancement control method provided by this invention can be used as a control redundancy. When the angle of attack sensor fails or the angle of attack information fails, the system can switch to the controller provided by this invention, enabling the aircraft to continue to maintain stable and safe flight, thereby improving the reliability of the control system. Attached Figure Description
[0031] Figure 1 This is a flowchart of the method in Embodiment 1 of the present invention.
[0032] Figure 2 This is a flowchart of the method in Embodiment 2 of the present invention.
[0033] Figure 3 This refers to the attitude control effect of a statically unstable aircraft without stabilization.
[0034] Figure 4 The attitude control effect when using angle of attack to stabilize a statically unstable aircraft.
[0035] Figure 5 The attitude control effect of using the method of this invention to stabilize a statically unstable aircraft. Detailed Implementation
[0036] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0037] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.
[0038] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0039] In the description of this application, it should be noted that the terms "upper," "vertical," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0040] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0041] Example 1
[0042] This embodiment provides a longitudinally relaxed static stability aircraft angle-of-attack stability augmentation control method, as detailed in the appendix of the instruction manual. Figure 1 The method includes the following steps:
[0043] S11. Obtain the aircraft's normal overload n through airborne inertial sensors;
[0044] S12. Obtain dynamic pressure Q through airborne atmospheric data sensors;
[0045] S13. Calculate the aircraft weight G based on the fuel level sensor information;
[0046] S14, Target value of roll angle φ c Provided by the aileron channel control law solution;
[0047] S15. Determine the stabilization control gain K. α ;
[0048] S16. Substitute the values obtained in steps S11 to S15 into formula (1) to calculate the elevator control command u, thereby controlling the aircraft to achieve angle-of-attack stabilization control:
[0049]
[0050] Where u is the elevator control command, K α The control gain, positive in sign, is obtained through parameter tuning based on the aircraft theoretical model. n represents the aircraft normal overload, which is dimensionless and measured by the onboard inertial sensor. φ c θ is the target roll angle value in degrees, Q is the dynamic pressure in Pascals, measured by the airborne atmospheric data sensor, G is the aircraft weight in Newtons, calculated by the airborne flight control computer based on fuel level sensor information, PID(θ) is the pitch angle PID control term, and PID(q) is the pitch rate PID control term.
[0051] It should be noted that PID(θ) and PID(q) are not innovative in this application, and the specific expressions of PID(θ) and PID(q) have many variations in the field of flight control law technology. Therefore, this application does not specify the specific expression of these two control terms.
[0052] The specific method for calculating the aircraft weight G based on the fuel level sensor information in step S13 is as follows:
[0053] G=G0+ρVg (2)
[0054] Where G0 is the weight of the aircraft without fuel, in Newtons; V is the fuel level sensor information, indicating the remaining fuel level, in liters; ρ is the fuel density, in kilograms per liter; and g is the acceleration due to gravity, taken as 9.8 m / s². 2 .
[0055] To avoid abrupt changes in elevator commands, the maximum rate of change of the roll angle target value can be limited, typically between 10° / s and 30° / s. The specific limit can be determined based on the aircraft's roll control agility. For aircraft with high agility, a larger limit can be selected, while for aircraft with low agility, a smaller limit can be selected.
[0056] To eliminate the impact of high-frequency noise from the normal overload on control quality, a filter is added to the normal overload signal. The filter transfer function is: s is a complex variable representing the frequency in the Laplace transform domain.
[0057] When the elevator is deflected downwards, the elevator control command is positive; when the elevator is deflected upwards, the elevator control command is negative.
[0058] When an aircraft rolls to the right, the roll angle is positive; when it rolls to the left, the roll angle is negative.
[0059] Normal overload is positive when it is upward and negative when it is downward.
[0060] Example 2:
[0061] This embodiment is provided based on Embodiment 1.
[0062] For an aircraft with a constant mass propelled by electric power, the aircraft weight G described in Example 1 is a constant value. Therefore, Example 2 is proposed, and thus Example 2 can also be considered a special case of Example 1, as follows:
[0063] The control structure of a longitudinally relaxed static stability aircraft angle-of-attack augmentation control method is as follows:
[0064]
[0065] Where u represents the elevator control command. The control gain, positive in sign, is obtained through parameter tuning based on the aircraft theoretical model. n represents the aircraft normal overload, which is dimensionless and measured by the onboard inertial sensor. φ c θ is the target roll angle value in degrees, Q is the dynamic pressure in Pascals, measured by the airborne atmospheric data sensor, PID(θ) is the pitch angle PID control term, and PID(q) is the pitch rate PID control term.
[0066] It should be noted that PID(θ) and PID(q) are not innovative in this application, and the specific expressions of PID(θ) and PID(q) have many variations in the field of flight control law technology. Therefore, this application does not specify the specific expression of these two control terms.
[0067] As per the instruction manual Figure 2As shown, combining formula (5), the steps for achieving longitudinally relaxed static stability control of aircraft without angle of attack are as follows:
[0068] S21. Obtain the aircraft's normal overload n through airborne inertial sensors;
[0069] S22. Obtain dynamic pressure Q through airborne atmospheric data sensors;
[0070] S23, Target value of roll angle φ c Provided by the aileron channel control law solution;
[0071] S24. Determine the stabilization control gain.
[0072] S25. Substitute the values obtained in steps S21 to S24 into formula (2) to calculate the elevator control command u, and then control the aircraft to achieve angle-of-attack stabilization control.
[0073] To prevent sudden changes in elevator commands, the roll angle target value is limited to a rate of change of 10° / s.
[0074] To eliminate the impact of high-frequency noise from the normal overload on control quality, a filter is added to the normal overload signal. The filter transfer function is:
[0075] The elevator control command is positive when the elevator is deflected downwards and negative when the elevator is deflected upwards.
[0076] The rules stipulate that the roll angle is positive when the aircraft rolls to the right and negative when it rolls to the left.
[0077] The normal overload is defined as positive when it is upward and negative when it is downward.
[0078] Example 3:
[0079] This embodiment provides a specific example based on Embodiments 1 and 2.
[0080] Example: For longitudinally relaxed static stability, the control gain for angle-of-attack stabilization of the aircraft is set to K. α =1.5, flight simulation results are as shown in the attached manual. Figure 3 ~Attached Figure 5 As shown. Flight simulation results show that the longitudinally relaxed static stability aircraft angle-of-attack stabilization control method proposed in this invention can achieve stabilization control for longitudinally relaxed static stability aircraft, and can achieve the same quality of stabilization control as angle-of-attack stabilization.
[0081] Example 4
[0082] This embodiment provides a computer device, which includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the methods of Embodiment 1, Embodiment 2, or Embodiment 3.
[0083] Example 5
[0084] This embodiment provides a computer-readable storage medium storing a computer program, which is executed by a processor to implement the methods of Embodiment 1, Embodiment 2, or Embodiment 3.
Claims
1. A longitudinally relaxed static stability aircraft angle-of-attack-free stability augmentation control method, characterized in that: Includes the following steps: S11. Obtain the aircraft's normal overload n through airborne inertial sensors; S12. Obtain dynamic pressure Q through airborne atmospheric data sensors; S13. Calculate the aircraft weight G based on the fuel level sensor information; S14, Target value of roll angle φ c Provided by the aileron channel control law solution; S15. Determine the stabilization control gain K. α ; S16. Substitute the values obtained in steps S11 to S15 into formula (1) to calculate the elevator control command u, thereby controlling the aircraft to achieve angle-of-attack stabilization control: Where u is the elevator control command, K α The control gain, positive in sign, is obtained through parameter tuning based on the aircraft theoretical model. n represents the aircraft normal overload, which is dimensionless and measured by the onboard inertial sensor. φ c θ is the target roll angle value in degrees, Q is the dynamic pressure in Pascals, measured by the airborne atmospheric data sensor, G is the aircraft weight in Newtons, calculated by the airborne flight control computer based on fuel level sensor information, PID(θ) is the pitch angle PID control term, and PID(q) is the pitch rate PID control term.
2. The longitudinally relaxed static stability aircraft angle-of-attack stabilization control method according to claim 1, characterized in that: The specific method for calculating the aircraft weight G based on the fuel level sensor information in step S13 is as follows: G=G0+ρVg (2) Where G0 is the weight of the aircraft without fuel, in Newtons; V is the fuel level sensor information, indicating the remaining fuel level, in liters; ρ is the fuel density, in kilograms per liter; and g is the acceleration due to gravity, taken as 9.8 m / s². 2 .
3. The longitudinally relaxed static stability aircraft angle-of-attack stabilization control method according to claim 1, characterized in that: The maximum rate of change of the target roll angle is limited to 10° / s to 30° / s.
4. The longitudinally relaxed static stability aircraft angle-of-attack stabilization control method according to claim 1, characterized in that: A filter is added to the normal overload signal, and the filter transfer function is: s is a complex variable representing the frequency in the Laplace transform domain.
5. The longitudinally relaxed static stability aircraft angle-of-attack stabilization control method according to claim 1, characterized in that: When the elevator is deflected downwards, the elevator control command is positive; when the elevator is deflected upwards, the elevator control command is negative.
6. The longitudinally relaxed static stability aircraft angle-of-attack stabilization control method according to claim 1, characterized in that: When an aircraft rolls to the right, the roll angle is positive; when it rolls to the left, the roll angle is negative.
7. The longitudinally relaxed static stability aircraft angle-of-attack stabilization control method according to claim 1, characterized in that: Normal overload is positive when it is upward and negative when it is downward.
8. A computer device, characterized in that: The computer device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the method as claimed in any one of claims 1-7.
9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and the processor executes the computer program to implement the method as described in any one of claims 1-7.