阅读说明：本技术 一种飞机操纵系统地面动态特性测试方法 (Method for testing ground dynamic characteristics of airplane control system ) 是由 侯世芳 徐坚 孙曦 张峰 杨博文 张振环 莫斌 刘旋 于 2020-05-09 设计创作，主要内容包括：本发明属于航空实验发展领域,公开了一种飞机操纵系统地面动态特性测试方法,操纵系统动态特性试验是评判飞机操纵系统特性的重要试验,试验方法的正确与否,决定着试验数据的可信度。本发明从工程应用的角度出发,给出具体可实施的试验条件、试验方法要求、试验原理及试验数据处理,对研究飞机操纵系统的稳定性及动态特性具有非常重要的意义。使工程设计人员能够直观的了解系统的动态特性,及时掌握系统的动态信息,是飞机研制及改进改型不可或缺的分析及验证手段。还可用于进行其他系统的动态特性研究,尤其是扫频控制及频域数据分析方法可用于进行其他相关系统的频率响应试验及进行相关的幅频、相频数据分析,来研究系统的动态特性。(The invention belongs to the field of aviation experimental development and discloses a method for testing the ground dynamic characteristics of an aircraft control system. From the perspective of engineering application, the invention provides specific practicable test conditions, test method requirements, test principles and test data processing, and has very important significance for researching the stability and dynamic characteristics of the aircraft control system. Engineering designers can visually know the dynamic characteristics of the system and timely master the dynamic information of the system, and the method is an indispensable analysis and verification means for aircraft development, improvement and modification. The method can be used for carrying out frequency response tests of other related systems and carrying out related amplitude-frequency and phase-frequency data analysis to research the dynamic characteristics of the system.)

1. A method for testing the ground dynamic characteristics of an airplane control system is characterized in that,

1) requirements of test conditions

The test needs to meet the following conditions and requirements:

a) the test must be performed on a real iron bird test stand 1:1 with the airplane;

b) the sensor testing system works normally, the mechanical control system works normally, the stability increasing system is controlled to work normally, and the hydraulic system works normally; high-precision angle sensors are arranged on control surfaces of the elevator, the rudder and the aileron, and all sensor signals are conditioned to form a frequency response analysis system;

c) the high-precision servo loading system is powered by a hydraulic source and applies an excitation signal to the system;

d) the frequency response analysis system can carry out amplitude-frequency and phase-frequency analysis on the system in real time;

2) principle of experiment

During the frequency response test, the dynamic analysis system provides an external instruction signal for the mechanical displacement signal generator to drive the signal generator to work, the mechanical signal generator operates the steering column, the steering wheel or the pedals to move, and during the motion process of the operation system, the dynamic analysis system respectively records the output signals of the sensors at each measuring point and analyzes the amplitude attenuation and the phase lag of the control surface relative to the steering column, the steering wheel or the pedals and the steering column, the steering wheel or the pedal force respectively;

3) frequency sweep control and frequency domain data analysis

In the test, the excitation signal adopts a sine signal, the transfer function of the control system is complex and is decomposed into a real part and an imaginary part, and the amplitude-frequency characteristic and the phase-frequency characteristic of the transfer function are respectively obtained;

during the test, logarithmic frequency is used as an abscissa, amplitude is used as a linear ordinate for amplitude frequency, phase frequency is used as a linear ordinate for phase angle, and an amplitude frequency and phase frequency characteristic curve of the system is drawn, namely the logarithmic frequency characteristic curve of the system and also a bode diagram;

a) frequency sweep control

The sweep frequency excitation signal is divided into analog excitation and digital excitation and is determined by the self characteristics of the sweep frequency equipment; the frequency of the analog excitation is continuous, the digital excitation is discrete and discontinuous, and the calculation method is that the highest frequency is logarithmized compared with the lowest frequency, and then the logarithmized result is multiplied by the point number in an octave to obtain the frequency point number;

b) amplitude frequency analysis

According to the excitation time of each frequency point, continuously acquiring data of each measured quantity, namely physical quantity or voltage quantity, making a root mean square of each measured quantity, making a corresponding ratio according to requirements, and taking 20lg to obtain an amplitude-frequency value of the frequency point;

c) phase frequency analysis

For a given excitation frequency, the corresponding period time T is a constant, the period signal has a time to cross the mean value, and two signals for correlation analysis need to be synchronous data acquisition; taking half of the excitation frequency period as a reference during calculation, and enabling the excitation frequency period to be equal to 180 degrees of phase; the time of each measurement signal crossing the mean line can be obtained by linear interpolation of adjacent positive and negative points, the change rate of the point is large and easy to capture, then the time t in the direction of less than 180 degrees of the displacement relative to the force signal is calculated, the positive and negative values are obtained in advance, the phase time of a plurality of periods is averaged, and the statistical error can be reduced, wherein the calculation method comprises the following steps:

t is the period time of the excitation signal, T is the test time point, n is the total number of periods, i is the number of periods, and theta (omega) is a phase angle;

in the transfer function of the control system in the step 3), the real part of the denominator is not zero, so that the phase-frequency function of the transfer function is not abrupt change, as the phase-frequency analysis is limited by 180 degrees of the periodic function, if the calculation result is that the phase frequency jumps from-170 degrees to 165 degrees, the phase-frequency function is-195 degrees, and if the phase frequency jumps to-170 degrees again, the system has a link of advanced differentiation, and if the phase frequency jumps and abruptly changes around 180 degrees, the phase-frequency angle is combined with the amplitude-frequency characteristic, so that whether the phase-frequency angle lags or leads can be determined;

4) reading of test data

The test data can be read by real-time frequency response analysis software.

2. The method for testing the ground dynamic characteristics of the aircraft control system according to claim 1, wherein the transfer function of the control system in the step 3) is as follows:

y(s) is a laplace transform of the output quantity, x(s) is a laplace transform of the input quantity, g(s) is a system transfer function, s is a complex variable, ω is an angular frequency, ω is 2 π f, f is a frequency, j is an imaginary unit, a (ω) is a real frequency characteristic, and b (ω) is an imaginary frequency characteristic.

3. The method for testing the ground dynamic characteristics of the aircraft control system according to claim 1, wherein the amplitude frequency of the transfer function in step 3 is as follows:

g (ω) is amplitude-frequency characteristic, a (ω) is real-frequency characteristic, and b (ω) is imaginary-frequency characteristic.

4. The method for testing the ground dynamic characteristics of the aircraft control system according to claim 1, wherein the phase frequency of the transfer function in step 3 is as follows:

where ω is 2 pi f and θ (ω) is a phase frequency characteristic.

5. The method for testing the ground dynamic characteristics of the aircraft control system according to claim 1, wherein in step b) of step 3), if the frequency response analysis equipment can only calculate the voltage, if the frequency response analysis equipment is not set, the 1V voltage is taken as a reference corresponding to 0dB, the ratio of the corresponding physical quantity is only used for calculating the amplitude value of the voltage root mean square and then subtracting the amplitude value of the voltage root mean square, and the amplitude-frequency vertical coordinate decibel value obtained in the way is converted by using the calibration coefficient of the sensor; the following were used:

let k₁As a calibration coefficient of force, k₂Is the calibration coefficient of displacement, F is force, w is displacement, V₁As magnitude of force, V₂Is the displacement amplitude, then

V₁＝k₁F

V₂＝k₂w

The dB value of amplitude frequency k (omega) is obtained by measurement

From the formula (4)

6. The method for testing the ground dynamic characteristics of the aircraft control system according to claim 1, in step 3) b, the decibel value corresponding to each starting frequency is influenced by the problem of ground interference in the whole test experiment, as can be seen from the test curve of each measurement; determining the decibel value corresponding to the initial frequency by adopting a static calibration method, and calculating the values of the rest frequencies through the attenuated decibel value; due to the non-linearity of the system, the state of the static calibration is consistent with the excitation state used in the experiment, such as: the test is carried out with +/-20 kgf, and the +/-20 kgf is calibrated when the calibration is carried out, including the clearance and the displacement formed by positive and negative forces.

7. The method for testing the ground dynamic characteristics of the aircraft control system according to claim 1, wherein in step 3 c) a joint time domain analysis method is used for carrying out time-frequency analysis on signals and observing the change process of the signal frequency; in order to facilitate the analysis of the phase-frequency curve, the sweep data is subjected to phase correction processing.

8. The method for testing the ground dynamic characteristics of the aircraft control system according to claim 1, wherein in the step 3, a) frequency subdivision is needed, 50 frequency points are set by a tenfold frequency range in engineering, and 2 to 3 octaves are taken; therefore, the frequency point number used in the test can be calculated according to the sweep frequency range of the test.

Technical Field

The invention belongs to the field of aviation test research and development, and particularly relates to a method for testing ground dynamic characteristics of an aircraft control system, a test principle and a frequency domain data processing method.

Background

The GJB185-86 section 8.3 in piloted aircraft (fixed wing) flight quality provides a requirement that the dynamic characteristic allows control surface hysteresis, and provides a step control force input for pilot excitation and a response requirement of the aircraft; the defects are that the requirements of practical test conditions, test methods, test principles and test data processing are not given.

The automatic control principle only introduces the performance index of the transient response and the commonly used graphic representation method of the frequency characteristic, such as a bode diagram representation method and the like. The defects that concrete practicable test conditions, test method requirements, test principles and test data processing are not given, and the distance is far away from actual engineering application.

Disclosure of Invention

The dynamic characteristic test of the control system is an important test for judging the characteristics of the aircraft control system, so whether the test method is correct or not directly determines the reliability of test data. The invention overcomes the defects in the prior art, and provides a test condition requirement, a test method, a test principle, a test flow and a frequency response data processing method of a ground dynamic characteristic test method of an airplane control system from the perspective of engineering application through repeated groping.

Technical scheme

Method for testing ground dynamic characteristics of airplane control system

1) Requirements of test conditions

The test needs to meet the following conditions and requirements:

e) the test must be performed on a real iron bird test stand with aircraft 1: 1.

f) The sensor testing system works normally, the mechanical control system works normally, the stability increasing system is controlled to work normally, and the hydraulic system works normally. High-precision angle sensors are arranged on control surfaces of the elevator, the rudder and the aileron, and all sensor signals are conditioned to obtain a frequency response analysis system.

g) The high-precision servo loading system (signal generator) is powered by a hydraulic source and applies an excitation signal to the system.

h) The frequency response analysis system can perform amplitude-frequency and phase-frequency analysis on the system in real time.

2) Principle of experiment

During the frequency response test, the dynamic analysis system provides an external command signal for the mechanical displacement signal generator to drive the signal generator to work, the mechanical signal generator operates the steering column, the steering wheel or the pedals to move, and during the operation of the operation system, the dynamic analysis system records the output signals of the sensors at the measuring points respectively and analyzes the amplitude attenuation and the phase lag of the control surface relative to the steering column, the steering wheel or the pedals and the steering column, the steering wheel or the pedal force respectively. The schematic diagram of the test is shown in figure 1.

3) Frequency sweep control and frequency domain data analysis

During test, the excitation signal is a sine signal, the transfer function of the control system is complex and can be decomposed into a real part and an imaginary part, and the amplitude-frequency characteristic and the phase-frequency characteristic of the transfer function are obtained respectively.

During the test, logarithmic frequency is used as an abscissa, amplitude is used as a linear ordinate for amplitude frequency, and phase angle is used as a linear ordinate for phase frequency, and amplitude frequency and phase frequency characteristic curves of the system are drawn, namely logarithmic frequency characteristic curves of the system and also Bode diagrams.

d) Frequency sweep control

The frequency sweep excitation signal is divided into analog excitation and digital excitation, and is mainly determined by the self characteristics of the frequency sweep equipment. The frequency of the analog excitation is continuous, the digital excitation is discrete and discontinuous, and the calculation method is that the highest frequency is logarithmized compared with the lowest frequency, and then the logarithmized result is multiplied by the point number in an octave to obtain the frequency point number.

e) Amplitude frequency analysis

And according to the excitation time of each frequency point, continuously acquiring data of each measured quantity (physical quantity or voltage quantity), making a root mean square of each measured quantity, making a corresponding ratio according to requirements, and taking 20lg to obtain the amplitude-frequency value of the frequency point.

f) Phase frequency analysis

For a given excitation frequency, the corresponding period time T is constant, there is time for the periodic signal to cross the mean, and the two signals to be correlated must be acquired synchronously. The calculation is based on half the period of the excitation frequency, equal to 180 ° in phase. The time of each measurement signal crossing the mean line can be obtained by linear interpolation of adjacent positive and negative points, the change rate of the point is large and easy to capture, then the time t in the direction of less than 180 degrees of the displacement relative to the force signal is calculated, the positive and negative values are obtained in advance, the phase time of a plurality of periods is averaged, and the statistical error can be reduced, wherein the calculation method comprises the following steps:

t is the period time of the excitation signal, T is the test time point, n is the total number of periods, i is the number of periods, and theta (omega) is the phase angle.

In the transfer function of the control system in the step 3, the real part of the denominator is not zero, so that the phase-frequency function of the transfer function is not abrupt, since the phase-frequency analysis is limited by 180 degrees of the periodic function, if the calculation result is that the phase frequency jumps from-170 degrees to 165 degrees, the phase-frequency function is-195 degrees, and if the phase frequency jumps to-170 degrees again, the system has a link of leading differentiation, and if the phase frequency jumps and abruptly changes around 180 degrees, the phase-frequency angle is combined with the amplitude-frequency characteristic, so that whether the phase-frequency angle lags or leads can be determined.

4) Reading of test data

The test data can be read by real-time frequency response analysis software.

The transfer function of the control system in the step 3 is as follows:

y(s) is a laplace transform of the output quantity, x(s) is a laplace transform of the input quantity, g(s) is a system transfer function, s is a complex variable, ω is an angular frequency, ω is 2 π f, f is a frequency, j is an imaginary unit, a (ω) is a real frequency characteristic, and b (ω) is an imaginary frequency characteristic.

The amplitude and frequency of the transfer function in step 3 are:

g (ω) is amplitude-frequency characteristic, a (ω) is real-frequency characteristic, and b (ω) is imaginary-frequency characteristic.

The phase frequency of the transfer function in step 3 is:

where ω is 2 pi f and θ (ω) is a phase frequency characteristic.

In the step b in the step 3), if the frequency response analysis equipment can only calculate the voltage, and when the frequency response analysis equipment is not set, the voltage of 1V is taken to correspond to 0dB as a reference, the ratio of the corresponding physical quantity only calculates the amplitude value of the voltage root-mean-square and then subtracts the amplitude value, so that the obtained amplitude-frequency vertical coordinate decibel value is converted by using the calibration coefficient of the sensor.

The following were used:

let k₁As a calibration coefficient of force, k₂Is the calibration coefficient of displacement, F is force, w is displacement, V₁As magnitude of force, V₂Is the displacement amplitude, then

V₁＝k₁F

V₂＝k₂w

The dB value of amplitude frequency k (omega) is obtained by measurement

From the formula (4)

In step 3) b, the decibel value corresponding to each starting frequency may have an influence due to the ground interference in the whole test experiment, as can be seen from the test curve of each measurement. The decibel value corresponding to the initial frequency can be determined by adopting a static calibration method, and the values of the other frequencies can be obtained by calculating the attenuated decibel value. Due to the non-linearity of the system, the state of the static calibration is consistent with the excitation state used in the experiment, such as: the test is carried out with +/-20 kgf, and the +/-20 kgf is calibrated when the calibration is carried out, including the clearance and the displacement formed by positive and negative forces.

In step 3 c) the time-frequency analysis of the signal can also be performed by using a joint time-domain analysis method to observe the change process of the signal frequency. In order to facilitate the analysis of the phase-frequency curve, the sweep data may be subjected to phase correction.

In step 3, a) frequency subdivision is required, and engineering should set 50 frequency points in a tenfold frequency range, and 2 to 3 octaves can be adopted. Therefore, the frequency point number used in the test can be calculated according to the sweep frequency range of the test.

The invention can also be used for researching the dynamic characteristics of other systems, in particular to a frequency sweep control and frequency domain data analysis method which can be used for carrying out frequency response tests of other related systems and carrying out related amplitude-frequency and phase-frequency data analysis to research the dynamic characteristics of the system.

Technical effects

Engineering designers can visually know the dynamic characteristics of the system and timely master the dynamic information of the system, and the method is an indispensable analysis and verification means for aircraft development, improvement and modification. Thus, the economic efficiency of this test is immeasurable.

Drawings

FIG. 1 is a schematic diagram of a dynamic test of a steering system.

Detailed Description

The invention is described in further detail below with reference to the following detailed description and accompanying drawings:

method for testing ground dynamic characteristics of airplane control system

1) Requirements of test conditions

The test needs to meet the following conditions and requirements:

a) the test must be performed on a real iron bird test stand with aircraft 1: 1.

b) The sensor testing system works normally, the mechanical control system works normally, the stability increasing system is controlled to work normally, and the hydraulic system works normally. High-precision angle sensors are arranged on control surfaces of the elevator, the rudder and the aileron, and all sensor signals are conditioned to obtain a frequency response analysis system.

c) The high-precision servo loading system (signal generator) is powered by a hydraulic source and applies an excitation signal to the system.

d) The frequency response analysis system can perform amplitude-frequency and phase-frequency analysis on the system in real time.

2) Principle of experiment

During the frequency response test, the dynamic analysis system provides an external command signal for the mechanical displacement signal generator to drive the signal generator to work, the mechanical signal generator operates the steering column, the steering wheel or the pedals to move, and during the operation of the operation system, the dynamic analysis system records the output signals of the sensors at the measuring points respectively and analyzes the amplitude attenuation and the phase lag of the control surface relative to the steering column, the steering wheel or the pedals and the steering column, the steering wheel or the pedal force respectively. The schematic diagram of the test is shown in figure 1.

3) Frequency sweep control and frequency domain data analysis

During test, the excitation signal is a sine signal, the transfer function of the control system is complex and can be decomposed into a real part and an imaginary part, and the amplitude-frequency characteristic and the phase-frequency characteristic of the transfer function are obtained respectively.

During the test, logarithmic frequency is used as an abscissa, amplitude is used as a linear ordinate for amplitude frequency, and phase angle is used as a linear ordinate for phase frequency, and amplitude frequency and phase frequency characteristic curves of the system are drawn, namely logarithmic frequency characteristic curves of the system and also Bode diagrams.

g) Frequency sweep control

The frequency sweep excitation signal is divided into analog excitation and digital excitation, and is mainly determined by the self characteristics of the frequency sweep equipment. The frequency of the analog excitation is continuous, the digital excitation is discrete and discontinuous, and the calculation method is that the highest frequency is logarithmized compared with the lowest frequency, and then the logarithmized result is multiplied by the point number in an octave to obtain the frequency point number.

h) Amplitude frequency analysis

And according to the excitation time of each frequency point, continuously acquiring data of each measured quantity (physical quantity or voltage quantity), making a root mean square of each measured quantity, making a corresponding ratio according to requirements, and taking 20lg to obtain the amplitude-frequency value of the frequency point.

i) Phase frequency analysis

For a given excitation frequency, the corresponding period time T is constant, there is time for the periodic signal to cross the mean, and the two signals to be correlated must be acquired synchronously. The calculation is based on half the period of the excitation frequency, equal to 180 ° in phase. The time of each measurement signal crossing the mean line can be obtained by linear interpolation of adjacent positive and negative points, the change rate of the point is large and easy to capture, then the time t in the direction of less than 180 degrees of the displacement relative to the force signal is calculated, the positive and negative values are obtained in advance, the phase time of a plurality of periods is averaged, and the statistical error can be reduced, wherein the calculation method comprises the following steps:

t is the period time of the excitation signal, T is the test time point, n is the total number of periods, i is the number of periods, and theta (omega) is the phase angle.

In the transfer function of the control system in the step 3, the real part of the denominator is not zero, so that the phase-frequency function of the transfer function is not abrupt, since the phase-frequency analysis is limited by 180 degrees of the periodic function, if the calculation result is that the phase frequency jumps from-170 degrees to 165 degrees, the phase-frequency function is-195 degrees, and if the phase frequency jumps to-170 degrees again, the system has a link of leading differentiation, and if the phase frequency jumps and abruptly changes around 180 degrees, the phase-frequency angle is combined with the amplitude-frequency characteristic, so that whether the phase-frequency angle lags or leads can be determined.

4) Reading of test data

The test data can be read by real-time frequency response analysis software.

The transfer function of the control system in the step 3 is as follows:

y(s) is a laplace transform of the output quantity, x(s) is a laplace transform of the input quantity, g(s) is a system transfer function, s is a complex variable, ω is an angular frequency, ω is 2 π f, f is a frequency, j is an imaginary unit, a (ω) is a real frequency characteristic, and b (ω) is an imaginary frequency characteristic.

The amplitude and frequency of the transfer function in step 3 are:

g (ω) is amplitude-frequency characteristic, a (ω) is real-frequency characteristic, and b (ω) is imaginary-frequency characteristic.

The phase frequency of the transfer function in step 3 is:

where ω is 2 pi f and θ (ω) is a phase frequency characteristic.

In the step b in the step 3), if the frequency response analysis equipment can only calculate the voltage, and when the frequency response analysis equipment is not set, the voltage of 1V is taken to correspond to 0dB as a reference, the ratio of the corresponding physical quantity only calculates the amplitude value of the voltage root-mean-square and then subtracts the amplitude value, so that the obtained amplitude-frequency vertical coordinate decibel value is converted by using the calibration coefficient of the sensor.

The following were used:

let k₁As a calibration coefficient of force, k₂Is the calibration coefficient of displacement, F is force, w is displacement, V₁As magnitude of force, V₂Is the displacement amplitude, then

V₁＝k₁F

V₂＝k₂w

The dB value of amplitude frequency k (omega) is obtained by measurement

From the formula (4)

In step 3) b, the decibel value corresponding to each starting frequency may have an influence due to the ground interference in the whole test experiment, as can be seen from the test curve of each measurement. The decibel value corresponding to the initial frequency can be determined by adopting a static calibration method, and the values of the other frequencies can be obtained by calculating the attenuated decibel value. Due to the non-linearity of the system, the state of the static calibration is consistent with the excitation state used in the experiment, such as: the test is carried out with +/-20 kgf, and the +/-20 kgf is calibrated when the calibration is carried out, including the clearance and the displacement formed by positive and negative forces.

In step 3 c) the time-frequency analysis of the signal can also be performed by using a joint time-domain analysis method to observe the change process of the signal frequency. In order to facilitate the analysis of the phase-frequency curve, the sweep data may be subjected to phase correction.

In step 3, a) frequency subdivision is required, and engineering should set 50 frequency points in a tenfold frequency range, and 2 to 3 octaves can be adopted. Therefore, the frequency point number used in the test can be calculated according to the sweep frequency range of the test.

1. Preparation before testing

Before testing, all the reference systems including the installation of elevators, ailerons and rudder control surface sensors, the inspection of mechanical systems and the working state of a stability augmentation system are checked by combining a test schematic diagram; according to the test state point, a stability augmentation system configuration is arranged on the tester, so that the stability augmentation system selects a control rate according to the configuration; checking a frequency response analysis system; and (5) checking a signal cross-linking line.

2. Selection of test conditions

Such as: applying a sinusoidal displacement signal from a neutral position at the point of application with a signal generator, a ═ a₀sin(ωt)，A₀20mm, 2 pi f, and f 0.1-1 Hz, wherein A is amplitude and f is frequency. And analyzing the amplitude-frequency characteristic and the phase-frequency characteristic of the output-to-input pair.