CN118012118A - Stability enhancement control gain design method for aircraft with longitudinal relaxation of static stability - Google Patents
Stability enhancement control gain design method for aircraft with longitudinal relaxation of static stability Download PDFInfo
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- CN118012118A CN118012118A CN202410081184.2A CN202410081184A CN118012118A CN 118012118 A CN118012118 A CN 118012118A CN 202410081184 A CN202410081184 A CN 202410081184A CN 118012118 A CN118012118 A CN 118012118A
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- 230000003068 static effect Effects 0.000 title claims abstract description 53
- 238000000034 method Methods 0.000 title claims abstract description 20
- 230000003416 augmentation Effects 0.000 claims description 27
- 230000005484 gravity Effects 0.000 claims description 11
- 230000008859 change Effects 0.000 claims description 9
- 238000004364 calculation method Methods 0.000 abstract description 8
- 230000000694 effects Effects 0.000 abstract description 5
- 230000008569 process Effects 0.000 description 3
- 238000009966 trimming Methods 0.000 description 3
- 238000013016 damping Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
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Abstract
The invention discloses a method for designing stability enhancement control gain of an aircraft with longitudinal relaxation of static stability, which comprises the steps of respectively determining an elevator control efficiency coefficient and an elevator line slope by drawing a curve, then determining an equivalent static stability expected value, and further calculating the stability enhancement control gain by a quantitative calculation formula. The invention establishes the relationship between the variable representing the stability and operability of the aircraft, such as the longitudinal relaxation static stability of the aircraft, the elevator operating efficiency coefficient and the like, and the stability-increasing control gain, reflects the quantitative influence of the gain on the stability of the aircraft, can accurately design and obtain the expected equivalent static stability, further quantitatively evaluate the stability-increasing effect, does not need repeated gain adjustment for many times, has high gain design efficiency and has better practicability.
Description
Technical Field
The invention belongs to the technical field of aviation aircrafts, and particularly relates to a stability enhancement control gain design method for an aircraft with longitudinal relaxation of static stability.
Background
Adopt vertical relaxation quiet stability, can promote the flight performance of aircraft by a wide margin, main advantage is as follows:
(1) The maneuverability and agility of the aircraft are improved;
(2) The operating efficiency of the elevator is increased, the horizontal tail area can be reduced, and the structure weight is reduced;
(3) The elevator control efficiency is enhanced, the trimming rudder quantity is reduced, and the trimming resistance is reduced;
(4) The lift loss of the tail wing is reduced, even the lift is changed into positive lift, and the lift-drag ratio of the whole aircraft is improved;
(5) Meanwhile, the lift-drag ratio is increased, the trimming resistance is reduced, and the airplane range and the airplane time are also increased.
The stationarity, i.e., the relative distance from the aerodynamic center of the aircraft to the center of gravity of the aircraft, is positive when the aerodynamic center is behind the center of gravity, as shown in fig. 2, and the aircraft is stationary. As shown in fig. 3, while the aerodynamic center is negative in static stability before the center of gravity, the aircraft is static unstable. The aeroplane with the longitudinal relaxation static stability is very close to the gravity center, and even before the gravity center, the aeroplane becomes weak and stable even unstable, so that the aeroplane with the longitudinal relaxation static stability needs to rely on stability enhancement control to ensure the stability of the aeroplane in flight.
At present, longitudinal stability augmentation control is mainly realized through attack angle feedback control, the attack angle feedback control gain is usually determined according to engineering experience or short-period modal damping ratio after stability augmentation, and a quantitative calculation method or formula is not available, so that the following defects exist:
(1) The stability enhancement control gain is determined according to engineering experience or the short-period modal damping ratio after stability enhancement, and the proper value can be obtained only by adjusting the gain for a plurality of times, so that the workload is increased;
(2) The influence of the stability enhancement control gain on the stability cannot be quantitatively analyzed;
(3) The quantitative relation between the variable representing the stability and operability of the aircraft, such as the longitudinal relaxation static stability of the aircraft, the elevator operating efficiency coefficient and the like, and the stability enhancement control gain cannot be established.
Disclosure of Invention
The invention aims to provide a stability enhancement control gain design method for an aircraft with longitudinal relaxation of static stability, and aims to solve the problems.
The invention is realized mainly by the following technical scheme:
A stability augmentation control gain design method for an aircraft with longitudinal relaxation of static stability comprises the following steps:
s1, calculating through aircraft pneumatic data to obtain an elevator operation efficiency coefficient
S2, calculating the lift line slope through the aircraft pneumatic data
S3, obtaining the static stability K n of the aircraft according to the overall design parameters of the aircraft;
s4, determining an expected value of equivalent static stability after stability augmentation
Step S5, substituting each numerical value obtained in the steps S1 to S4 into a formula (1), and calculating to obtain the stability enhancement control gain:
In order to better realize the invention, further, when the elevator is controlled to deflect downwards, the elevator control command is positive; when the elevator is controlled to deflect upwards, the elevator control command is negative; the pitching moment of the head of the airplane is positive, and the pitching moment of the low head of the airplane is negative.
In order to better implement the present invention, in step S1, a curve of the change of the pitch moment coefficient along with the elevator is drawn according to the aerodynamic data of the aircraft, and the slope of the curve is the elevator operating efficiency coefficient
To better realize the invention, further, the elevator steering efficiency coefficientIs negative in sign, wherein/>The physical meaning of (2) is: every 1 degree of change of the elevator, the change amount of the generated pitching moment coefficient is generated.
In order to better implement the present invention, in step S2, a curve of the aircraft lift coefficient along with the attack angle is drawn according to the aircraft aerodynamic data, and the slope of the curve is the slope of the lift line
In order to better implement the present invention, further, in the step S3, when the aerodynamic center of the aircraft is located behind the center of gravity, the value of the aircraft stationarity K n is positive; the value of the aircraft stationarity K n is negative when the aircraft aerodynamic center is located forward of the center of gravity.
In order to better implement the present invention, further, in the step S4, the equivalent static stability expected valueThe sign of (2) is positive and takes a value within the range of 3% -15%, wherein/>Meaning of (2): aircraft with longitudinal relaxation of static stability, and the stability is obtained by stability augmentation control and is/>Is quite stable for aircraft.
The beneficial effects of the invention are as follows:
(1) The stability-increasing control gain can be directly calculated through variables such as the aircraft static stability, the elevator operating efficiency coefficient and the like, the gain adjustment is not required to be repeatedly carried out, and the gain design efficiency is high;
(2) The invention provides a quantitative calculation method and steps of stability augmentation control gain, establishes the relationship between the stability and operability-representing variables such as the longitudinal relaxation static stability of the aircraft, the elevator operating efficiency coefficient and the like and the stability augmentation control gain, reflects the quantitative influence of the gain on the stability of the aircraft in the calculation process, can accurately design and obtain the expected equivalent static stability, further quantitatively evaluates the stability augmentation effect, and has better practicability.
Drawings
FIG. 1 is a flow chart of a method of designing a stability augmentation control gain for an aircraft that longitudinally relaxes the stability of the present invention;
FIG. 2 is a schematic illustration of a longitudinal static aircraft trim;
FIG. 3 is a schematic illustration of a longitudinal static unstable aircraft trim;
Fig. 4 is a pitch attitude control step response curve with the stability augmentation control in example 2.
Detailed Description
Example 1:
The design method of the stability augmentation control gain of the aircraft with the longitudinal relaxation of the static stability comprises the steps of:
Wherein, For the slope of the line of ascent,
For the elevator operating efficiency coefficient,
K n is the aircraft stationarity, and K n is positive when stationary, or negative when stationary,
The expected value of equivalent static stability after stability enhancement is positive.
Preferably, as shown in fig. 1, the present invention specifically includes the following steps:
s1, calculating to obtain an elevator control efficiency coefficient through aircraft pneumatic data Drawing a curve of which the pitching moment coefficient changes along with the elevator according to aircraft aerodynamic data, wherein the slope of the curve is the elevator operating efficiency coefficient;
s2, calculating to obtain the slope of the lift line through aircraft pneumatic data Drawing a curve of the change of the lift coefficient of the aircraft along with the attack angle, wherein the slope of the curve is the slope of a lift line;
S3, obtaining the static stability K n of the aircraft according to the overall design parameters of the aircraft;
S4, determining an expected value of equivalent static stability after stability augmentation
S5, substituting each numerical value obtained in the steps S1 to S4 into the formula (1), and calculating to obtain the stability enhancement control gain K α.
Preferably, the equivalent static stability expected value in step S4Is a variable of the construction of the present invention,/>Meaning of (2): aircraft with longitudinal relaxation of static stability can obtain a static stability/> by stability augmentation controlEquivalent stability of the aircraft and thus can be used/>To quantitatively evaluate the stability augmentation effect.
Preferably, in order to smoothly implement the step of calculating the gain design of the stability augmentation control of the aircraft with longitudinal relaxation of static stability, the invention provides that:
(1) When the elevator is controlled to deflect downwards, the elevator control command is positive; when the elevator is controlled to deflect upwards, the elevator control command is negative;
(2) Providing that the pitching moment of the head of the airplane is positive; the pitching moment of the low head of the airplane is negative;
(3) Defining the elevator operating efficiency coefficient described in step S1 The sign is negative, and the magnitude of the sign is equal to the change quantity of the pitching moment coefficient generated by the change of the elevator by 1 degree;
(4) The aircraft stationarity K n in the step S3 is positive when the aerodynamic center of the aircraft is located behind the center of gravity; the aerodynamic center of the aircraft is located in front of the center of gravity, and its value is negative.
Preferably, the longitudinal relaxation static stability aircraft stability augmentation control adopts an attack angle feedback control method, and the specific flight control law controller structure is as follows:
u＝Kα·(α-αt) (2)
wherein u is an elevator control command,
K α is the stability enhancement control gain,
Alpha is the angle of attack and the angle of incidence,
Alpha t is the trim angle of attack.
The invention provides a quantitative calculation method and steps of stability enhancement control gain, which establishes the relationship between the stability and operability-representing variables such as the longitudinal relaxation static stability of an airplane, the operating efficiency coefficient of an elevator and the like and the stability enhancement control gain, and can directly calculate the stability enhancement control gain according to the variables such as the static stability of the airplane, the operating efficiency coefficient of the elevator and the like, so that the gain design efficiency is high. Meanwhile, the calculation process of the stability augmentation control gain reflects the quantitative influence of the gain on the stability of the aircraft, and the expected equivalent static stability can be accurately designed, so that the stability augmentation effect is quantitatively evaluated.
Example 2:
a method for designing stability-increasing control gain of aircraft with longitudinal relaxation of static stability, wherein the aircraft is in static unstable layout and the slope of a lift line Elevator operating efficiency coefficient/>Static stability K n = -3%, equivalent static stability expected value after stability enhancement/>The stability enhancement control gain is:
after the stability augmentation control gain K α =0.8 is used for the stability augmentation control of the aircraft, as shown in fig. 4, it can be seen that the pitch angle posture not only can realize the stability control, but also has good time domain response characteristics. The invention provides a quantitative calculation method and steps of stability augmentation control gain, establishes the relationship between the stability and operability-representing variables such as the longitudinal relaxation static stability of the aircraft, the elevator operating efficiency coefficient and the like and the stability augmentation control gain, reflects the quantitative influence of the gain on the stability of the aircraft in the calculation process, can accurately design and obtain the expected equivalent static stability, further quantitatively evaluates the stability augmentation effect, and has better practicability.
The foregoing description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and any simple modification, equivalent variation, etc. of the above embodiment according to the technical matter of the present invention fall within the scope of the present invention.
Claims (7)
1. A stability augmentation control gain design method for an aircraft with longitudinal relaxation of static stability is characterized by comprising the following steps:
s1, calculating through aircraft pneumatic data to obtain an elevator operation efficiency coefficient
S2, calculating the lift line slope through the aircraft pneumatic data
S3, obtaining the static stability K n of the aircraft according to the overall design parameters of the aircraft;
s4, determining an expected value of equivalent static stability after stability augmentation
Step S5, substituting each numerical value obtained in the steps S1 to S4 into a formula (1), and calculating to obtain the stability enhancement control gain:
2. The method for designing an increased stability control gain of an aircraft with a longitudinally relaxed static stability according to claim 1, wherein the elevator control command is positive when the elevator is controlled to deflect downward; when the elevator is controlled to deflect upwards, the elevator control command is negative; the pitching moment of the head of the airplane is positive, and the pitching moment of the low head of the airplane is negative.
3. The method for designing gain of aircraft with longitudinally relaxed static stability according to claim 1 or 2, wherein in step S1, a curve of change of pitch moment coefficient with elevator is drawn according to aircraft aerodynamic data, and the slope of the curve is the elevator operating efficiency coefficient
4. A method of designing a stability augmentation control gain of an aircraft having a longitudinally relaxed static stability as set forth in claim 3, wherein said elevator operating efficiency coefficientIs negative in sign, wherein/>The physical meaning of (2) is: every 1 degree of change of the elevator, the change amount of the generated pitching moment coefficient is generated.
5. The method for designing stability enhancement control gain of aircraft with longitudinally relaxed static stability according to claim 1 or 2, wherein in step S2, a curve of aircraft lift coefficient with angle of attack is drawn according to aircraft aerodynamic data, and the slope of the curve is the slope of the lift line
6. The method for designing an increased stability control gain of an aircraft with a longitudinally relaxed static stability according to claim 1, wherein in the step S3, when the aerodynamic center of the aircraft is located behind the center of gravity, the value of the aircraft static stability K n is positive; the value of the aircraft stationarity K n is negative when the aircraft aerodynamic center is located forward of the center of gravity.
7. The method for designing gain of aircraft with longitudinally relaxed static stability according to claim 1 or 6, wherein in step S4, the expected value of equivalent static stability isThe sign of (2) is positive and takes a value within the range of 3% -15%, wherein/>Meaning of (2): aircraft with longitudinal relaxation of static stability, and the stability is obtained by stability augmentation control and is/>Is quite stable for aircraft.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410081184.2A CN118012118A (en) | 2024-01-19 | 2024-01-19 | Stability enhancement control gain design method for aircraft with longitudinal relaxation of static stability |
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| CN202410081184.2A CN118012118A (en) | 2024-01-19 | 2024-01-19 | Stability enhancement control gain design method for aircraft with longitudinal relaxation of static stability |
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| CN118012118A true CN118012118A (en) | 2024-05-10 |
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