Method for judging function reduction of aircraft control system based on hysteresis dead zone

Abstract

The invention provides a method for judging function reduction of an aircraft control system. According to the method, a hysteresis dead zone serves as a judgment index for function reduction of an aircraft elevator control system. The determination method for determining that the index is the hysteresis dead zone comprises the following steps: step 1, carrying out equivalent dynamic modeling on an aircraft elevator control system; step 2, equivalent dynamic model parameter conversion; step 3, engineering treatment; 4, determining an equivalent coefficient; 5, constructing an equivalent linearization model; step 6, constructing a hysteresis operator; 7, hysteresis loop simulation analysis is carried out; 8, performing simulation analysis on the oscillation characteristics of the control surface; according to the evaluation index selected by the method, the hysteresis dead zone is obtained by a model-based method, the accuracy is high, the monitoring is easy, and the engineering application value is very high. The method provided by the invention is low in model judgment and test cost and less in test condition limitation, and can effectively make up for the limitation of flight test and ground test times.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft performance evaluation, relates to aircraft elevator control system components, and specifically to a method for determining aircraft control system function degradation based on a hysteresis dead zone. Background Art

[0002] The aircraft elevator control system is a command and control system that is directly related to the aircraft's control quality. Only by responding to the pilot's instructions in a timely manner and achieving human-machine integration in combat can the aircraft platform exert its due combat capability.

[0003] Frequent takeoffs and landings of fighter jets and high-difficulty combat maneuvers such as large-angle turns during combat can easily lead to fatigue of the aircraft's elevator control system, affecting the control quality and causing a decline in the fighter's combat capability. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for determining the reduction in function of an aircraft control system based on a hysteresis dead zone, so as to solve the technical problem that it is difficult to strike a balance between the accuracy and the test cost of the determination method in the prior art.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0006] A method for determining whether an aircraft elevator control system has a reduced function. The method uses a hysteresis dead zone as a determination index for whether an aircraft elevator control system has a reduced function.

[0007] The determination index is the hysteresis dead zone, and the determination method is as follows: based on the equivalent linearization model of the aircraft elevator control system, a hysteresis operator of the aircraft elevator control system is constructed, and then the hysteresis loop is simulated and analyzed, and the control surface oscillation characteristics are simulated and analyzed, and finally the hysteresis dead zone is determined as the determination index for the reduction of the function of the aircraft elevator control system.

[0008] The aircraft elevator control system comprises a front cabin manual control mechanism, a transmission mechanism in the fuselage, a fuselage tail movement mechanism and a control surface mechanism.

[0009] The method for determining that the determination indicator is a hysteresis dead zone comprises the following steps:

[0010] Step 1: Equivalent dynamic modeling of aircraft elevator control system:

[0011] Step 101, based on the structure of the aircraft elevator control system, using the lumped parameter modeling method, the damping, stiffness, mass, clearance and friction of the hard transmission components in the aircraft elevator control system are concentrated and simplified directly according to the motion characteristics of the hard transmission components, and an equivalent dynamic model of the aircraft elevator control system with four degrees of freedom is established.

[0012] The equivalent dynamic model includes part 1, part 2, part 3 and part 4; part 1 is an equivalent dynamic model equivalent to the front cabin hand control mechanism, part 2 is an equivalent dynamic model equivalent to the transmission mechanism in the fuselage, part 3 is an equivalent dynamic model equivalent to the motion mechanism of the tail of the fuselage, and part 4 is an equivalent dynamic model equivalent to the control surface mechanism.

[0013] Step 2: Calculation of equivalent dynamic model parameters:

[0014] By determining the lumped parameters and equivalent conversion, the equivalent dynamic model parameter values ​​of Part 1, Part 2, Part 3 and Part 4 in the equivalent dynamic model obtained in step 1 are determined.

[0015] The equivalent dynamic model parameters include m i 、c i , as well as

[0016] Where:

[0017] i is the number of the i-th part of the equivalent dynamic model of the aircraft elevator control system, i = 1, 2, 3, 4;

[0018] m i is the equivalent mass of the hard transmission components of the i-th part of the equivalent dynamic model of the aircraft elevator control system;

[0019] c i is the equivalent damping of the hard transmission components in the i-th part of the equivalent dynamic model of the aircraft elevator control system;

[0020] is the equivalent stiffness of the hinge moving parts of the i-th part of the equivalent dynamic model of the aircraft elevator control system;

[0021] is the equivalent stiffness of the fixed support components of the i-th part of the equivalent dynamic model of the aircraft elevator control system.

[0022] Step 3: Engineering Processing:

[0023] According to the equivalent dynamic model parameters obtained in step 2, the nonlinear dry friction term, the hinge motion elastic force term with gap, and the fixed position elastic force term with gap in the equivalent dynamic model are respectively engineered.

[0024] Step 4: Determine the equivalent coefficient:

[0025] The equivalent linearization method is used to calculate the nonlinear dry friction term after the engineering treatment in step 3. The equivalent viscous damping coefficient Elastic force term of hinge motion with gap The corresponding equivalent stiffness coefficient Fixed-position elastic force term with gap The corresponding equivalent stiffness coefficient

[0026] in:

[0027] i is the number of the i-th part of the aircraft elevator control system, i = 1, 2, 3, 4;

[0028] x i is the displacement of the mass block in the i-th part of the equivalent linearized model of the aircraft elevator control system;

[0029] is the velocity of the mass block in the i-th part of the equivalent linearized model of the aircraft elevator control system;

[0030] u is the displacement of the front cockpit control components;

[0031] M i is the normal force at the contact point of the dry friction term in the i-th part of the equivalent linearized model of the aircraft elevator control system;

[0032] e i is the active position gap of the i-th part of the equivalent linearized model of the aircraft elevator control system;

[0033] d i is the fixed position gap of the i-th part of the equivalent linearized model of the aircraft elevator control system.

[0034] Step 5: Construct an equivalent linear model:

[0035] In C i ≥e i , B i ≥d i Under the constraint condition of Equivalent stiffness coefficient And the equivalent stiffness coefficient Substitute into the equivalent dynamic model in step one, and convert part 1, part 2, part 3 and part 4 of the equivalent dynamic model obtained in step one into equivalent linearized models respectively.

[0036] in:

[0037] C i is the amplitude of the cosine function of the relative displacement between the mass block of the ith part and the mass block of the previous part of the equivalent linearized model of the aircraft elevator control system;

[0038] B iis the amplitude of the cosine function of the displacement of the mass block in the ith part of the equivalent linearized model of the aircraft elevator control system.

[0039] Step 6: Construction of hysteresis operator:

[0040] Step 601, based on the equivalent linearized model of the aircraft elevator control system obtained in step 5, derive and solve the amplitude-frequency characteristic control equations and the phase-frequency characteristic control equations of part 1, part 2, part 3 and part 4 to obtain the amplitude-frequency characteristic control equation group and the phase-frequency characteristic control equation group of the aircraft elevator control system.

[0041] Step 602, obtaining a hysteresis operator of the aircraft elevator control system according to the amplitude-frequency characteristic control equation group and the phase-frequency characteristic control equation group of the aircraft elevator control system obtained in step 601.

[0042] Step 7: Hysteresis loop simulation analysis:

[0043] Based on the amplitude-frequency characteristic control equation group and the phase-frequency characteristic control equation group of the aircraft elevator control system obtained in step 601, a simulation analysis is performed to obtain the influence of the clearance and dry friction on the hysteresis loop of the aircraft elevator control system.

[0044] Step 8: Simulation analysis of rudder surface oscillation characteristics:

[0045] Step 801, based on the hysteresis operator of the aircraft elevator control system obtained in step 602, a hysteresis nonlinear model of the man-machine closed-loop aircraft elevator control system is established.

[0046] Step 802, based on the influence of the clearance and dry friction force on the hysteresis loop of the aircraft elevator control system obtained in step 7, by increasing the active position clearance e=[e1 e2 e3 e4] of the aircraft elevator control system or the normal force M=[M1 M2 M3 M4] of the contact point in the dry friction force, increasing the hysteresis dead zone value, and performing a control surface motion delay response analysis on the hysteresis nonlinear model under different hysteresis dead zones.

[0047] Step 803, based on the control surface motion delay response analysis obtained in step 802, determine to use the hysteresis dead zone as a criterion for determining whether the aircraft elevator control system function is degraded.

[0048] The present invention also has the following technical features:

[0049] Preferably, in step 5, the equivalent linearization model includes:

[0050] The equivalent linearized equation for Part 1 is:

[0051]

[0052] The equivalent linearized equation for Part 2 is:

[0053]

[0054] The equivalent linearized equation for Part 3 is:

[0055]

[0056] The equivalent linearized equation for Part 4 is:

[0057]

[0058] Where:

[0059] i is the number of the i-th part of the aircraft elevator control system, i = 1, 2, 3, 4;

[0060] is the acceleration of the mass block in the i-th part of the equivalent linearized model of the aircraft elevator control system;

[0061] The speed of the front cockpit control components;

[0062] is the equivalent viscous damping coefficient of the nonlinear dry friction term of the i-th part of the equivalent linearized model of the aircraft elevator control system;

[0063] is the equivalent stiffness coefficient corresponding to the elastic force term of the hinge motion with clearance in the i-th part of the equivalent linearized model of the aircraft elevator control system;

[0064] is the equivalent stiffness coefficient corresponding to the fixed position elastic force term with gap in the i-th part of the equivalent linearized model of the aircraft elevator control system.

[0065] Preferably, in step 602, the expression of the hysteresis operator of the aircraft elevator control system is:

[0066]

[0067] Where:

[0068] is a real number;

[0069] x4(t) is the displacement of the mass block of the equivalent linearized model of the rudder mechanism, which is equivalent to the deflection angle of the rudder surface of the aircraft elevator control system;

[0070] is the acceleration of the mass block of the equivalent linearized model of the rudder mechanism;

[0071] is the first harmonic amplitude of the relative displacement between the mass block of the equivalent linearized model of the rudder mechanism and the mass block of the equivalent linearized model of the tail motion mechanism of the fuselage;

[0072] is the phase lag angle of the first harmonic of the mass block of the equivalent linearized model of the rudder mechanism; t is the actuation time of the rudder movement;

[0073] u(t) is the displacement of the steering column of the front cockpit control component, and the excitation is a triangular wave;

[0074] U / 2 is the amplitude of the steering column displacement;

[0075] is the acceleration of the steering column displacement;

[0076]

[0077] Preferably, in step 602, the hysteresis dead zone of the hysteresis operator of the aircraft elevator control system

[0078] Preferably, in step seven, the effects of the gap and dry friction on the hysteresis loop of the aircraft elevator control system are as follows: the combat fatigue of the aircraft elevator control system is positively correlated with the hysteresis dead zone; under the same dry friction, the larger the gap of the aircraft elevator control system, the larger the phase lag angle, and the larger the hysteresis dead zone; under the same gap amount, the larger the dry friction, the more severe the phase lag, and the larger the hysteresis dead zone; the simulation results also show that no matter whether the active position gap e=[e1 e2e3 e4] or the normal force M=[M1 M2 M3 M4] of the contact point in the dry friction is increased, only one hysteresis loop appears at the origin, that is, the size, number and position of the gap have no effect on the number and position of the hysteresis loop, indicating the uniqueness of the hysteresis loop.

[0079] Preferably, in step 802, the different hysteresis dead zones include a step input truncation function hysteresis dead zone and a pulse function hysteresis dead zone.

[0080] Preferably, in step 802, the delayed response of the control surface movement is: as the hysteresis dead zone increases, the oscillation of the control surface increases, the convergence time increases, and the function of the aircraft elevator control system decreases; when the hysteresis dead zone value reaches 13.5 mm, the control surface oscillates with equal amplitude, and the aircraft elevator control system loses its function.

[0081] Furthermore, the determination method also includes step nine.

[0082] Step nine, according to the relationship between the hysteresis dead zone and the delayed response of the control surface movement obtained in step eight, based on the delayed response of the control surface movement, establish a corresponding relationship between the functional level of the aircraft elevator control system and the hysteresis dead zone interval value, and determine the functional level of the aircraft elevator control system according to the hysteresis dead zone value.

[0083] The present invention also protects a method for determining whether the function of an aircraft control system is reduced. The aircraft control system includes an aircraft elevator control system. The determination method uses a hysteresis dead zone as a determination indicator for whether the function of the aircraft control system is reduced.

[0084] Specifically, the determination method of the determination index being a hysteresis dead zone adopts the determination method of the determination index being a hysteresis dead zone in the above-mentioned determination method of aircraft elevator control system function reduction.

[0085] Compared with the prior art, the present invention has the following technical effects:

[0086] (I) Evaluation index selected by the method of the present invention: The hysteresis dead zone is obtained by a model-based method, which has high accuracy, is easy to monitor, and has high engineering application value.

[0087] (II) The method of the present invention is a model determination method with low test cost and few restrictions on test conditions, which can effectively make up for the limitation on the number of flight tests and ground tests.

[0088] (III) The present invention provides a new evaluation index for determining the functional level of an aircraft elevator control system. The lumped parameter model and the equivalent linearization method are used to obtain the hysteresis operator formula of the aircraft elevator control system. The hysteresis nonlinear model of the aircraft elevator control system is analyzed to find the evaluation index for the reduction of the control system function under aircraft fatigue combat, and the functional level of the aircraft elevator control system is divided based on the index. The effectiveness of the evaluation index proposed by the present invention is verified by actual flight parameter test data.

[0089] (IV) The mechanism model reflecting the hysteresis characteristics of the system described in the present invention is manifested as a hysteresis operator model between the displacement of the front cockpit and the corresponding deflection angle of the control surface in the aircraft elevator control system. Through the simulation analysis of the hysteresis operator model of the aircraft elevator control system, it is determined that the increase in the active position gap and dry friction value of the aircraft elevator control system causes the increase in the hysteresis dead zone. Further, a hysteresis nonlinear model of the aircraft elevator control system is established, and the simulation analysis shows that the increase in the hysteresis dead zone causes the oscillation of the control surface to increase, the aircraft control quality to decrease, and the function of the aircraft elevator control system to decrease. The hysteresis dead zone of the hysteresis loop formed by the displacement of the front cockpit control component and the corresponding deflection angle of the control surface can directly reflect the problem of reduced function of the aircraft elevator control system caused by combat fatigue. Therefore, the hysteresis dead zone is determined as an evaluation indicator for the reduced function of the aircraft elevator control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0090] Figure 1 This is a schematic diagram of the structure of the aircraft elevator control system.

[0091] Figure 2 It is the equivalent dynamic model of the aircraft elevator control system.

[0092] Figure 3 It is the equivalent linearization model of the aircraft elevator control system.

[0093] Figure 4 is the effect of the gap on the hysteresis loop.

[0094] Figure 5 This is the effect of dry friction on the hysteresis loop.

[0095] Figure 6 It is the hysteresis nonlinear model of the aircraft elevator control system.

[0096] Figure 7(a) shows the delayed response analysis of the aircraft elevator control system control surface motion under the hysteresis dead zone condition of the step input truncation function.

[0097] Figure 7(b) shows the delayed response analysis of the aircraft elevator control system control surface motion under the condition of pulse function hysteresis dead zone.

[0098] Figure 8(a) shows the hysteresis fitting result of the flight parameter data of the elevator control system of aircraft No. 1.

[0099] Figure 8(b) shows the hysteresis fitting result of the flight parameter data of the elevator control system of aircraft No. 2.

[0100] Fig. 9 This is the hysteresis dead zone trend diagram of the aircraft elevator control system.

[0101] The specific contents of the present invention are further described in detail below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0102] It should be noted that, unless otherwise specified, all aircraft systems, mechanisms and methods of use in the present invention all adopt aircraft systems, mechanisms and methods known in the prior art.

[0103] The present invention studies the characterization parameters of the combat fatigue of the control system, takes it as an evaluation index of the degradation of the function of the aircraft elevator control system, and provides a reference for the combat capability evaluation of the aircraft platform.

[0104] The present invention starts from the relationship between the combat fatigue of the aircraft elevator control system and the stability of the control surface, analyzes and determines the characteristic parameters reflecting the reduction of the control system function through hysteresis nonlinear modeling of the aircraft elevator control system, and divides the functional levels of the aircraft elevator control system based on the relationship between the characteristic parameters and the stability of the control surface movement, thereby realizing the judgment of the reduction of the function of the aircraft elevator control system.

[0105] In order to solve the problem of judging the reduced function of the aircraft elevator control system in the above-mentioned aircraft combat capability assessment, the present invention proposes a method of using the aircraft elevator control system hysteresis loop to model the hysteresis nonlinearity of the aircraft elevator control system. Through the analysis of the model working characteristics, the hysteresis dead zone of the hysteresis loop formed by the displacement of the front cockpit control component and the corresponding rudder surface deflection angle is determined as the aircraft elevator control system function reduction evaluation index. Aiming at the problem of judging the reduced function of the aircraft elevator control system in the aircraft combat capability assessment, the present invention proposes a model-based aircraft elevator control system function reduction index selection method.

[0106] The present invention provides a new evaluation index for evaluating the functional level of an aircraft elevator control system. The equivalent dynamic model of the control system is established by using a lumped parameter model. The hysteresis operator formula of the aircraft elevator control system is obtained by linearizing the equivalent dynamic model. The hysteresis dead zone evaluation index related to the fatigue of the control system is obtained by hysteresis operator simulation analysis. The influence of the hysteresis dead zone on the stability of the control surface is obtained by hysteresis nonlinear model simulation analysis of the aircraft elevator control system. According to the aircraft design manual, the functional level of the aircraft elevator control system is divided based on the hysteresis dead zone, and the effectiveness of the proposed function reduction determination method is verified by actual flight parameter data.

[0107] In accordance with the above technical scheme, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical scheme of this application fall within the protection scope of the present invention.

[0108] Embodiment 1:

[0109] This embodiment provides a method for determining whether the function of an aircraft elevator control system is degraded. The method uses a hysteresis dead zone as a determination index for whether the function of an aircraft elevator control system is degraded.

[0110] The aircraft elevator control system in this embodiment is a known aircraft elevator control system, such as Figure 1 As shown, it includes the front cabin manual control mechanism, the transmission mechanism in the fuselage, the fuselage tail movement mechanism and the control surface mechanism. Specifically:

[0111] Figure 1This is a schematic diagram of the structure of the aircraft elevator control system. During the takeoff and climbing phase of the aircraft, the pilot pulls back on the control column, which drives the elevator to deflect upward through mechanical transmission. The elevator is subjected to downward pressure, and the aircraft rises; similarly, during the cruising phase of the aircraft, the control column returns to its original position and the elevator remains horizontal; during the descent phase of the aircraft, the pilot pushes forward on the control column, which drives the elevator to deflect downward through mechanical transmission. The elevator is subjected to upward pressure, and the aircraft lowers its head.

[0112] like Figure 1 As shown, the aircraft elevator control system can be divided into four parts according to its installation position on the aircraft, namely the front cabin manual control mechanism, the transmission mechanism inside the fuselage, the fuselage tail movement mechanism and the control surface mechanism.

[0113] like Figure 1 As shown, the components of the front cabin hand control mechanism are composed of a control wheel, a control column tube, a control column lower arm and a transverse axis tie rod. The transmission mechanism in the fuselage refers to the control mechanism connected to the tie rod rocker arm in the middle of the fuselage. The tail movement mechanism of the fuselage includes an airtight box assembly and a fan-shaped rocker arm assembly. The rudder structure system includes an elevator shaft rocker arm assembly and its corresponding tie rod.

[0114] The method for determining the hysteresis dead zone as a determination indicator comprises the following steps:

[0115] Step 1: Equivalent dynamic modeling of aircraft elevator control system:

[0116] Step 101, based on the structure of the aircraft elevator control system, using the lumped parameter modeling method, the damping, stiffness, mass, clearance and friction of the hard transmission components in the aircraft elevator control system are concentrated and simplified directly according to the motion characteristics of the hard transmission components, and an equivalent dynamic model of the aircraft elevator control system with four degrees of freedom is established.

[0117] The equivalent dynamic model includes part 1, part 2, part 3 and part 4; part 1 is the equivalent dynamic model of the front cabin hand control mechanism, part 2 is the equivalent dynamic model of the transmission mechanism in the fuselage, part 3 is the equivalent dynamic model of the tail motion mechanism of the fuselage, and part 4 is the equivalent dynamic model of the control surface mechanism.

[0118] In this embodiment, based on Figure 1 The equivalent dynamic model of the aircraft elevator control system is established by the motion process in Figure 2 As shown, Figure 2 u is the displacement of the front cockpit control components, x i , m i , c i , e i , d i , f i cThey are the displacement, mass, damping, stiffness of the hinge moving parts, stiffness of the fixed support parts, clearance at the active position, clearance at the fixed position and dry friction of the i-th part.

[0119] like Figure 2 In the equivalent dynamic model shown, the direction of the arrow is the positive direction of force and displacement.

[0120] In the equivalent dynamic model, the equivalent dynamic models of each part are defined as follows: the front cabin hand control mechanism of the aircraft elevator control system (including the control column assembly and the bottom tie rod connected to it) is concentrated and simplified according to its motion characteristics, which is equivalent to the first part of the equivalent dynamic model of the aircraft elevator control system; the transmission mechanism in the fuselage of the aircraft elevator control system (including the transmission mechanism composed of the rocker arm and the tie rod) is concentrated and simplified according to its motion characteristics, which is equivalent to the second part of the equivalent dynamic model; the tail fuselage motion mechanism of the aircraft elevator control system (including the airtight box assembly and the rocker arm connected to the elevator tie rod) is equivalent to the third part of the equivalent dynamic model. The control surface mechanism of the aircraft elevator control system (including the elevator and the tie rod connected to it) is equivalent to the fourth part of the equivalent dynamic model.

[0121] like Figure 2 The relevant parameters in the equivalent dynamic model shown are defined as follows:

[0122] u is the displacement of the front cockpit control components;

[0123] F 0,1 It is the sum of the elastic force and the damping force of the hinge motion with clearance in the first part of the aircraft elevator control system caused by the displacement u;

[0124] is the elastic force term of the hinge motion with clearance in the i-th part of the equivalent dynamic model of the aircraft elevator control system;

[0125] The elastic force term of the fixed position with clearance in the i-th part of the equivalent dynamic model of the aircraft elevator control system;

[0126] x i is the displacement of the hard transmission component of the i-th part of the equivalent dynamic model of the aircraft elevator control system;

[0127] m i is the equivalent mass of the hard transmission components of the i-th part of the equivalent dynamic model of the aircraft elevator control system;

[0128] c i is the equivalent damping of the hard transmission components in the i-th part of the equivalent dynamic model of the aircraft elevator control system;

[0129] is the equivalent stiffness of the hinge moving parts of the i-th part of the equivalent dynamic model of the aircraft elevator control system;

[0130] is the equivalent stiffness of the fixed support component of the i-th part of the equivalent dynamic model of the aircraft elevator control system;

[0131] s d The displacements of the hard transmission components and clearance related parts in the i-th part of the equivalent dynamic model of the aircraft elevator control system;

[0132] The speed of the hard transmission components of the i-th part of the equivalent dynamic model of the aircraft elevator control system respectively;

[0133] is the acceleration of the hard transmission component of the i-th part of the equivalent dynamic model of the aircraft elevator control system;

[0134] d i is the fixed position clearance of the hard transmission components in the i-th part of the equivalent dynamic model of the aircraft elevator control system;

[0135] e i The active clearance of the hard transmission components in the i-th part of the equivalent dynamic model of the aircraft elevator control system;

[0136] f i c is the dry friction term of the i-th part of the equivalent dynamic model of the aircraft elevator control system;

[0137] M i is the normal force at the contact point of the dry friction term in the i-th part of the equivalent dynamic model of the aircraft elevator control system;

[0138] F i,j is the interaction force between the i-th and j-th parts of the equivalent dynamic model of the aircraft elevator control system;

[0139] i,j∈{1,2,3,4} corresponds to the label of each part of the equivalent dynamic model.

[0140] like Figure 2 In the equivalent dynamic model shown, the control motion equation between the control column and the elevator is:

[0141]

[0142] Among them, F i,j The expression is:

[0143]

[0144] like Figure 2In the equivalent dynamic model shown, the displacement s of each part related to the gap is d The relationship between and gap δ is described as:

[0145]

[0146] Where:

[0147] z is the displacement, δ and z are the independent variables of Formula 3, which can be changed according to the specific situation.

[0148] Consider the displacement s d The directionality of each part’s displacement s d The relationship between and the gap δ is further described as:

[0149]

[0150] Where:

[0151] sign is the sign function; z is the displacement. The independent variables z and δ of Formula 4 are consistent with those of Formula 3 and are changed according to the specific situation.

[0152] In this embodiment, the damping term of the system mainly includes two parts: one part is the damping of the hinge structure of the system itself, which can be treated as viscous damping and expressed as equivalent damping c i The other part is the damping caused by Coulomb friction, which is represented by the symbol f i c express, is the dry friction term of the i-th part. Specifically, the dry friction f of each part of the control system c The modified Coulomb friction model is expressed as:

[0153]

[0154] Where:

[0155] z is the displacement, and the independent variable z in equation 5 is changed according to the specific situation;

[0156] M is the normal force at the contact point;

[0157] represents the coefficient of kinetic friction determined by the tangential force;

[0158] μ d Indicates the sliding friction coefficient of the contact point;

[0159] μ s Represents the static friction coefficient of the contact point;

[0160] v s is the critical speed of static friction;

[0161] vd is the critical speed of maximum dynamic friction.

[0162] Step 2: Calculation of equivalent dynamic model parameters:

[0163] By determining the lumped parameters and equivalent conversion, the equivalent dynamic model parameter values ​​of Part 1, Part 2, Part 3 and Part 4 in the equivalent dynamic model obtained in step 1 are determined.

[0164] The equivalent dynamic model parameters of the aircraft elevator control system include m i 、c i , as well as Where: m i is the equivalent mass of the hard transmission component in the i-th part of the equivalent dynamic model; c i is the equivalent damping of the hard transmission component in the i-th part of the equivalent dynamic model; k i a is the equivalent stiffness of the hinge motion component of the i-th part of the equivalent dynamic model; is the equivalent stiffness of the fixed support component of the i-th part of the equivalent dynamic model.

[0165] Transmission ratio calculation: The transmission ratio is the ratio of the effective radius of the output arm to the effective radius of the input arm. Calculate the transmission ratio of each part by referring to the project aircraft Catia model and aircraft design manual and other relevant materials.

[0166] Calculation of equivalent mass: The mass of the translational component itself is the equivalent mass. For the rotating component, the moment of inertia of the component must be obtained first, and then the equivalent mass of the component is calculated. The equivalent mass m of the rotating component of the elevator control system of the project aircraft model is:

[0167]

[0168] Where:

[0169] I is the moment of inertia of the rotating part;

[0170] r L For rotating parts, enter the distance from the point to the turning point, i.e. the radius.

[0171] Equivalent stiffness calculation: For the tie rod, its equivalent stiffness k l for:

[0172] k l =ES A / lFormula 7.

[0173] Where:

[0174] l is the effective length of the tie rod;

[0175] SA is the effective cross-sectional area;

[0176] E is the elastic modulus of the material.

[0177] For rotating parts such as rocker arms and fan wheels, the equivalent stiffness k is:

[0178]

[0179] Among them, r i is the output radius, and J is the moment of inertia of the component.

[0180] Equivalent damping calculation: Structural damping is determined by equation 9:

[0181]

[0182] The size and mass of the components are obtained from the Catia model of the corresponding components, and the stiffness can be calculated from the finite element analysis. Select a certain point as the conversion point, and the clearance, displacement, damping, stiffness, mass and friction of the system are converted according to the following formula, namely:

[0183]

[0184] Where:

[0185] f i * are the actual clearance, displacement, damping, stiffness, mass and friction of the control system components; d i , x i , m i , c i , k i , f i It is the equivalent value after the actual parameters of each part of the control system are converted;

[0186] n represents the total transmission ratio from the local location to the conversion point, which is equal to the product of all rocker arm transmission ratios between the local location and the conversion point.

[0187] n=n1×n2×…×n i Formula 11.

[0188] Where:

[0189] n1,n2,n3,…,n i is the transmission ratio between the components.

[0190] According to the above formula, the model parameters are converted, and the corresponding parameters of each part of the equivalent dynamic model of the aircraft elevator control system are shown in the table. These lumped (or discrete) parameters are equivalent to the parameters of the original continuous system.

[0191] Table 1 Parameters of equivalent dynamic model of aircraft elevator control system

[0192]

[0193]

[0194] Step 3: Engineering Processing:

[0195] According to the equivalent dynamic model parameters obtained in step 2, the nonlinear dry friction term, the hinge motion elastic force term with gap, and the fixed position elastic force term with gap in the equivalent dynamic model are respectively engineered.

[0196] z is the displacement. The independent variable z in Equations 12, 13, and 14 is changed according to specific circumstances.

[0197] The nonlinear dry friction term is expressed in engineering terms as:

[0198]

[0199] The engineering expression of the elastic force term of hinge motion with gap is:

[0200]

[0201] The engineering expression of the fixed position elastic force term with gap is:

[0202]

[0203] Step 4: Determine the equivalent coefficient:

[0204] The equivalent linearization method is used to calculate the nonlinear dry friction term after the engineering treatment in step 3. The equivalent viscous damping coefficient Elastic force term of hinge motion with gap The corresponding equivalent stiffness coefficient Fixed-position elastic force term with gap The corresponding equivalent stiffness coefficient

[0205] In this embodiment, it is assumed that the control column of the aircraft elevator control system drives the pull rod to perform cosine motion, and the displacement of the control column is expressed as u = Acos (ωt). The displacement of the mass block of the i-th part of the equivalent linearized model is Then the velocity and acceleration of the mass block in the i-th part are Substituting the displacement, velocity and acceleration of the mass block of the i-th part into equation 14, we can obtain: The fixed position elastic force term with gap in the i-th part The corresponding equivalent stiffness coefficient for:

[0206]

[0207] in, Indicates the gap d i The corresponding phase lag angle is, A is the input signal of the model, that is, the amplitude of the cosine function of the steering column displacement, ω is the angular frequency, and t is the time; B i is the amplitude of the cosine function displacement of the mass block of the ith part, α i is the phase lag angle of the cosine function displacement, angle

[0208] Then, the nonlinear dry friction term in Equation 12 is The equivalent viscous damping coefficient for

[0209]

[0210] Substitute Equation 16 into Equation 1 and introduce the relative displacement Assuming relative displacement Substituting into equation 13, the elastic force term f of the hinge motion with gap is obtained by the equivalent linearization method: i k (y i ,d i ) corresponds to the equivalent stiffness coefficient for:

[0211]

[0212] In the formula, Indicates the gap e i The corresponding phase lag angle is C i is the amplitude of the cosine function of the relative displacement between the mass block of the i-th part and the mass block of the previous part, β i is the phase lag angle of the cosine function, angle

[0213]

[0214] Step 5: Construct an equivalent linear model:

[0215] In C i ≥e i , B i ≥d i Under the constraint condition of Equivalent stiffness coefficient And the equivalent stiffness coefficient Substitute into equation 1 in the equivalent dynamic model in step 1, and convert part 1, part 2, part 3, and part 4 of the equivalent dynamic model obtained in step 1 into equivalent linearized models respectively.

[0216] in:

[0217] e i is the active position gap of the i-th part of the equivalent linearized model of the aircraft elevator control system;

[0218] d i is the fixed position gap of the i-th part of the equivalent linearized model of the aircraft elevator control system.

[0219] In this embodiment, the equivalent linearization model is as follows: Figure 3 As shown, Figure 3 In, x i , m i , c i , e i , d i and f i c They are the displacement, mass, damping, stiffness of the hinge moving parts, stiffness of the fixed support parts, clearance at the active position, clearance at the fixed position and dry friction of the i-th part.

[0220] The equivalent linearized equation for Part 1 is:

[0221]

[0222] The equivalent linearized equation for Part 2 is:

[0223]

[0224] The equivalent linearized equation for Part 3 is:

[0225]

[0226] The equivalent linearized equation for Part 4 is:

[0227]

[0228] Where:

[0229] i is the number of the i-th part of the aircraft elevator control system, i = 1, 2, 3, 4;

[0230] m i is the equivalent mass of the hard transmission components of the i-th part of the equivalent dynamic model of the aircraft elevator control system;

[0231] x iis the displacement of the mass block in the i-th part of the equivalent linearized model of the aircraft elevator control system;

[0232] is the velocity of the mass block in the i-th part of the equivalent linearized model of the aircraft elevator control system;

[0233] is the acceleration of the mass block in the i-th part of the equivalent linearized model of the aircraft elevator control system;

[0234] u is the displacement of the front cockpit control components;

[0235] The speed of the front cockpit control components;

[0236] c i is the equivalent damping of the hard transmission components in the i-th part of the equivalent dynamic model of the aircraft elevator control system;

[0237] is the equivalent viscous damping coefficient of the nonlinear dry friction term of the i-th part of the equivalent linearized model of the aircraft elevator control system;

[0238] is the equivalent stiffness coefficient corresponding to the elastic force term of the hinge motion with clearance in the i-th part of the equivalent linearized model of the aircraft elevator control system;

[0239] is the equivalent stiffness coefficient corresponding to the fixed position elastic force term with gap in the i-th part of the equivalent linearized model of the aircraft elevator control system.

[0240] Step 6: Construction of hysteresis operator:

[0241] Step 601, based on the equivalent linearized model of the aircraft elevator control system obtained in step 5, derive and solve the amplitude-frequency characteristic control equations and the phase-frequency characteristic control equations of part 1, part 2, part 3 and part 4 to obtain the amplitude-frequency characteristic control equation group and the phase-frequency characteristic control equation group of the aircraft elevator control system.

[0242] When the steering column has a long motion cycle, the displacement of the front cockpit control component is more suitable for a triangular wave. The expression for the displacement u of the front cockpit control component is:

[0243]

[0244] Where:

[0245] T is the period of the triangle wave;

[0246] k is the number of cycles;

[0247] U / 2 is the amplitude of the triangle wave.

[0248] The Fourier expansion of equation 22 is:

[0249]

[0250] in:

[0251] n is the harmonic order of the Fourier expansion of the triangle wave;

[0252] is the amplitude of the nth harmonic of the Fourier expansion of the triangle wave.

[0253] According to the superposition principle, the linear system under the action of the excitation function is equal to the linear superposition of the output responses of its harmonics acting alone.

[0254] First, the output responses of the equivalent linearized equations of the aircraft elevator control system (Equations 18 to 21) caused by the harmonic excitations of Equation 23 are calculated, and then the responses are superimposed to obtain the total response of the system.

[0255] make represents the viscous damping ratio coefficient corresponding to the equivalent linearized model of the i-th part, represents the dry friction equivalent damping ratio coefficient corresponding to the equivalent linearized model of the i-th part, is the first-order torsional equivalent natural frequency corresponding to the equivalent linearized model of the i-th part, is the frequency ratio corresponding to the equivalent linearized model of the i-th part, is the amplitude of the relative displacement between the mass block of the ith part and the mass block of the previous part of the equivalent linearized model of the aircraft elevator control system caused by the nth harmonic excitation of the control stick triangular wave; is the phase lag angle of the relative displacement between the mass block of the ith part and the mass block of the previous part of the equivalent linearized model caused by the nth harmonic excitation of the triangular wave of the control column; is the amplitude of displacement of the mass block in the i-th part of the equivalent linearized model of the aircraft elevator control system caused by the n-th harmonic excitation of the control column triangular wave; is the phase lag angle of the displacement of the mass block in the i-th part of the equivalent linearized model caused by the n-th harmonic excitation of the triangular wave of the control column; i = 1, 2, 3, 4,

[0256] The equivalent linearized equation 18 in Part 1 introduces the relative displacement y1 = x1-u, assuming n=1,3,5,… Solving equation 18, we get the amplitude-frequency characteristic control equation of part 1 as follows:

[0257]

[0258] The phase-frequency characteristic control equation of Part 1 is expressed as:

[0259]

[0260] in,

[0261] The equivalent linearized equation 19 in Part 2 introduces the relative displacement y2 = x2 - x1, assuming n=1,3,5,… Solve equation 19 to obtain the amplitude-frequency characteristic control equation of part 2:

[0262]

[0263]

[0264] The phase-frequency characteristic control equation of Part 2 is expressed as:

[0265]

[0266] in:

[0267] Introduce the relative displacement y3 = x3 - x2 into the equivalent linearized equation 20 in Part 3, assuming n=1,3,5,… Solve equation 20 to obtain the amplitude-frequency characteristic control equation of part 3:

[0268]

[0269] The phase-frequency characteristic control equation of Part 3 is expressed as:

[0270]

[0271]

[0272] in,

[0273] The equivalent linearized equation 21 in Part 4 assumes n=1,3,5,…, then:

[0274]

[0275] Introducing the relative displacement y4=x4-x3, solving equation 21, the amplitude-frequency characteristic control equation of part 4 is expressed as:

[0276]

[0277] The phase-frequency characteristic control equation of Part 4 is expressed as:

[0278]

[0279] The above equations 33 to 43 are the amplitude-frequency and phase-frequency control equations of the equivalent linearized model of the aircraft elevator control system. They are a set of nonlinear high-order transcendental equations and there is no analytical solution. The motion response of each part is solved with the help of Newton's iteration method.

[0280] Step 602, obtaining a hysteresis operator of the aircraft elevator control system according to the amplitude-frequency characteristic control equation group and the phase-frequency characteristic control equation group of the aircraft elevator control system obtained in step 601.

[0281] In this embodiment, it is assumed that the displacement u of the front cockpit control component is a triangular wave. According to the equivalent linearization model of the aircraft elevator control system, the displacement u of the front cockpit control component of the aircraft elevator control system (i.e., Formula 22) and the control system rudder deflection angle x4 (i.e., Formula 38) satisfy the hysteresis operator of the aircraft elevator control system.

[0282] The expression of the hysteresis operator of the aircraft elevator control system is:

[0283]

[0284] Where:

[0285] is a real number;

[0286] x4(t) is the displacement of the mass block of the equivalent linearized model of the rudder mechanism, which is equivalent to the deflection angle of the rudder surface of the aircraft elevator control system;

[0287] is the acceleration of the mass block of the equivalent linearized model of the rudder mechanism;

[0288] is the first harmonic amplitude of the relative displacement between the mass block of the equivalent linearized model of the rudder mechanism and the mass block of the equivalent linearized model of the tail motion mechanism of the fuselage;

[0289] is the phase lag angle of the first harmonic of the mass block of the equivalent linearized model of the rudder mechanism; t is the actuation time of the rudder movement;

[0290] u(t) is the displacement of the steering column of the front cockpit control component, and the excitation is a triangular wave;

[0291] U / 2 is the amplitude of the steering column displacement;

[0292] is the acceleration of the steering column displacement;

[0293]

[0294] The hysteresis operator of the aircraft elevator control system has a finite slope, and the slope interval is [ρ1,ρ2].

[0295] Where:

[0296] ρ1 is the minimum value of the slope of the hysteresis operator;

[0297] ρ2 is the maximum value of the slope of the hysteresis operator.

[0298] Hysteresis Dead Band of Hysteresis Operator of Aircraft Elevator Control System

[0299] Step 7: Hysteresis loop simulation analysis:

[0300] Based on the amplitude-frequency characteristic control equation group and the phase-frequency characteristic control equation group of the aircraft elevator control system obtained in step 601, a simulation analysis is performed to obtain the influence of the clearance and dry friction on the hysteresis loop of the aircraft elevator control system.

[0301] In this embodiment, the phase lag angle of the aircraft elevator control system is It is related to the dry friction force and the gap amount (reflected by the equivalent stiffness after linearization). The active position gap e=[e1 e2 e3 e4], the fixed position gap d=[d1 d2d3 d4] or the normal force M=[M1 M2 M3 M4] of the contact point in the dry friction force all affect the shape of the hysteresis loop. Among the two types of gaps, the active position gap e with the greater influence is taken for study.

[0302] Step 701, let the steering column displacement excitation function amplitude U / 2 = 17.27 / 2 mm, the dry friction force M i =400N, angular frequency ω=1rad / s, change the active position gap e, and use Newton iteration method to solve the amplitude-frequency characteristic control equation group and phase-frequency characteristic control equation group of the aircraft elevator control system obtained in step six, that is, solve equations 33 to 43.

[0303] The changes in the characteristic parameters of the hysteresis loop of the aircraft elevator control system caused by the gap are shown in Table 2, where "↓" indicates a monotonic decrease and "↑" indicates a monotonic increase. The effects of the three groups of gaps in Table 2 on the hysteresis characteristics of the aircraft elevator control system are shown in Table 2. Figure 4 The solution results show that the combat fatigue of the aircraft elevator control system is positively correlated with the hysteresis dead zone. Under the same dry friction, the larger the gap of the aircraft elevator control system, the larger the phase lag angle and the larger the hysteresis dead zone.

[0304] Table 1 Effect of clearance on hysteresis loop related parameters of aircraft elevator control system

[0305]

[0306] Step 702, set the steering column displacement excitation function amplitude U / 2 = 17.27 / 2 mm, the clearance The simulation analysis of the elevator phase lag angle when the steering column displacement is at a swing frequency of ω = 1rad / s for three cases where the dry friction force is 350N, 400N, and 450N respectively is shown in Table 3. The hysteresis loop formed is as follows Figure 5 As shown in the figure and table, the results indicate that the changes in friction at multiple positions of the aircraft elevator control system are positively correlated with the combat fatigue of the aircraft elevator control system and the hysteresis dead zone. Under the same clearance, the greater the dry friction, the more severe the phase lag and the larger the hysteresis dead zone.

[0307] The simulation results of step 701 and step 702 also show that no matter whether M or e is increased, only one hysteresis loop appears at the origin, that is, the size, number and position of the gap have no effect on the number and position of the hysteresis loop, indicating the uniqueness of the hysteresis loop.

[0308] Table 2 Effect of dry friction on hysteresis loop related parameters of aircraft elevator control system

[0309]

[0310] Step 8: Simulation analysis of rudder surface oscillation characteristics:

[0311] Step 801, based on the hysteresis operator of the aircraft elevator control system obtained in step 602, combined with the known linear time-invariant system composed of the pilot description function and the flight attitude dynamics, a hysteresis nonlinear model of the man-machine closed-loop aircraft elevator control system is established.

[0312] In this embodiment, the structure of the hysteresis nonlinear model is as follows: Figure 6 As shown, the hysteresis operator L(u,e1,…,e4,d1,…,d4) of the aircraft elevator control system corresponds to equation 44. The input of the operator L is Corresponding to the hysteresis operator in Equation 44, the steering column displacement excitation, r is the hysteresis nonlinear model input, is the output of the linear time-invariant system state space equation composed of flight attitude dynamics, the output of operator L is the displacement x4 of the mass block of the equivalent linearized model of the rudder mechanism, the state variable of the state space equation of the hysteresis nonlinear model is q, and the state parameter matrix is:

[0313]

[0314] B=[00-2080] T ,C=[-500000],D=[0].

[0315] Step 802, based on the influence of the clearance and dry friction force on the hysteresis loop of the aircraft elevator control system obtained in step 7, by increasing the active position clearance e or dry friction M of the aircraft elevator control system, increasing the hysteresis dead zone value, and performing control surface motion delay response analysis on the hysteresis nonlinear model under different hysteresis dead zones.

[0316] In step 802, different hysteresis dead zones include step input truncation function hysteresis dead zone and pulse function hysteresis dead zone. As shown in Figure 7 (a) and Figure 7 (b): as the hysteresis dead zone increases, the oscillation of the control surface increases, the convergence time increases, and the function of the aircraft elevator control system decreases; when the hysteresis dead zone value reaches 13.5mm, the control surface oscillates with equal amplitude, and the aircraft elevator control system loses its function.

[0317] Step 803, based on the control surface motion delay response analysis obtained in step 802, determine to use the hysteresis dead zone as a criterion for determining whether the aircraft elevator control system function is degraded.

[0318] In this embodiment, according to the conclusion of step eight, it can be obtained that the degradation level of the function of the aircraft elevator control system is associated with the hysteresis dead zone. When the hysteresis dead zone increases, the rudder surface oscillation is aggravated, causing the rudder surface stability to deteriorate, resulting in a decrease in flight quality and a degradation of the function of the aircraft elevator control system. When the rudder surface oscillates seriously, it will cause control instability and loss of function of the aircraft elevator control system. Therefore, the hysteresis dead zone (i.e., the hysteresis loop dead zone) corresponding to the hysteresis loop formed by the control column displacement and the elevator deflection angle can reflect the degradation of the function of the aircraft elevator control system.

[0319] Step nine, based on the relationship between the hysteresis dead zone obtained in step eight and the delayed response of the control surface movement, the aircraft elevator control system is classified into functional degradation levels based on the hysteresis dead zone, and the functional degradation level of the aircraft elevator control system is determined according to the functional degradation level.

[0320] In step nine, according to the design requirements for the aircraft elevator control system in the "Aircraft Design Manual Volume 12 Flight Control System and Hydraulic System Design": step signals of different amplitudes can be input, and the stability of the rudder movement can be determined by the time domain method. If no divergence or equal amplitude oscillation occurs under all amplitudes, and the overshoot of the response is less than 30%, and the transition process adjustment time is less than 1s, then its stability is considered acceptable in engineering. Therefore, the aircraft elevator control system response overshoot is less than 30%, and the transition process adjustment time is less than 1s as requiring maintenance. The division results in this step are shown in Table 4.

[0321] Table 4 Classification of aircraft elevator control system function degradation based on hysteresis dead zone

[0322]

[0323] In step nine, further, based on the data recorded by the flight parameter recorder of an A-check cycle of the aircraft elevator control system, the method for determining the decline in the function of the aircraft elevator control system is verified. Specifically, the method includes the following sub-steps:

[0324] In the first step, the backlash-like model is used to perform hysteresis fitting on the flight parameter data of the elevator control system column displacement and elevator deflection angle of each aircraft, and the hysteresis dead zone value is extracted. The hysteresis fitting effects of the flight parameter data of two flights are selected as shown in Figure 8(a) and Figure 8(b), where D is the hysteresis dead zone value.

[0325] R 2 is the correlation index, which is used to calculate the fitting effect between the estimated output of the parameter identification model of the data set and the actual output of the data set. 2 The calculation formula is

[0326]

[0327] Among them, R 2 A value equal to 1 indicates the best fitting effect. is the estimated output of the sample point k in the data set, y k is the actual output of sample point k in the dataset, is the average value of the sample points in the data set, and N is the number of samples in the data set.

[0328] The second step is to draw a hysteresis dead zone trend diagram of the aircraft elevator control system, such as Fig. 9 As shown in the figure, it can be seen that with the increase in the number of flights, the hysteresis dead zone increases, and the function of the aircraft elevator control system decreases. When the aircraft is about to end the A-check cycle, the hysteresis dead zone value corresponding to the number of flights enters the functional degradation range and maintenance is required, which is consistent with the planned maintenance at the end of the aircraft A-check cycle. This verifies the effectiveness of the proposed method for determining the degradation of the aircraft elevator control system based on the hysteresis dead zone.

[0329] Embodiment 2:

[0330] This embodiment provides a method for determining degradation of the function of an aircraft control system. The aircraft control system is a known aircraft control system, and the aircraft control system includes an aircraft elevator control system, an aircraft rudder control system, and an aircraft aileron control system.

[0331] This determination method uses the hysteresis dead zone as a determination indicator of the degradation of the aircraft control system function.

[0332] The determination method for determining that the judgment indicator is a hysteresis dead zone adopts the determination method for determining that the judgment indicator is a hysteresis dead zone in the method for determining the reduction in function of the aircraft elevator control system given in Example 1.

[0333] In this embodiment, the method for determining that the judgment indicator is a hysteresis dead zone through the aircraft rudder control system and the aircraft aileron control system is basically the same as the method for determining that the judgment indicator is a hysteresis dead zone through the aircraft elevator control system given in Example 1, and will not be repeated here.

Claims

1. A method for determining whether an aircraft elevator control system has reduced functionality, characterized in that: The determination method uses the hysteresis dead zone as a determination index for the degradation of the aircraft elevator control system function.

2. The method for determining whether the function of an aircraft elevator control system is degraded according to claim 1, wherein: The determination index is the hysteresis dead zone, and the determination method is as follows: based on the equivalent linearization model of the aircraft elevator control system, a hysteresis operator of the aircraft elevator control system is constructed, and then the hysteresis loop is simulated and analyzed, and the control surface oscillation characteristics are simulated and analyzed, and finally the hysteresis dead zone is determined as the determination index for the reduction of the function of the aircraft elevator control system.

3. The method for determining the function degradation of an aircraft elevator control system as claimed in claim 2, wherein the aircraft elevator control system comprises a front cabin manual control mechanism, a transmission mechanism in the fuselage, a fuselage tail movement mechanism and a control surface mechanism; and characterized in that: The method for determining that the determination indicator is a hysteresis dead zone comprises the following steps: Step 1: Equivalent dynamic modeling of aircraft elevator control system: Step 101, based on the structure of the aircraft elevator control system, using a lumped parameter modeling method, the damping, stiffness, mass, clearance and friction of the hard transmission components in the aircraft elevator control system are concentrated and simplified directly according to the motion characteristics of the hard transmission components, and an equivalent dynamic model of the aircraft elevator control system with four degrees of freedom is established; The equivalent dynamic model includes part 1, part 2, part 3 and part 4; part 1 is an equivalent dynamic model of the front cabin hand control mechanism, part 2 is an equivalent dynamic model of the transmission mechanism in the fuselage, part 3 is an equivalent dynamic model of the tail motion mechanism of the fuselage, and part 4 is an equivalent dynamic model of the control surface mechanism; Step 2: Calculation of equivalent dynamic model parameters: Determine the equivalent dynamic model parameter values ​​of Part 1, Part 2, Part 3 and Part 4 in the equivalent dynamic model obtained in step 1 by determining the lumped parameters and equivalent conversion; The equivalent dynamic model parameters include m i 、c i , as well as Where: i is the number of the i-th part of the equivalent dynamic model of the aircraft elevator control system, i = 1, 2, 3, 4; m i is the equivalent mass of the hard transmission components of the i-th part of the equivalent dynamic model of the aircraft elevator control system; c i is the equivalent damping of the hard transmission components in the i-th part of the equivalent dynamic model of the aircraft elevator control system; is the equivalent stiffness of the hinge moving parts of the i-th part of the equivalent dynamic model of the aircraft elevator control system; is the equivalent stiffness of the fixed support component of the i-th part of the equivalent dynamic model of the aircraft elevator control system; Step 3: Engineering Processing: According to the equivalent dynamic model parameters obtained in step 2, the nonlinear dry friction term, the hinge motion elastic force term with gap, and the fixed position elastic force term with gap in the equivalent dynamic model are respectively processed by engineering methods; Step 4: Determine the equivalent coefficient: The equivalent linearization method is used to calculate the nonlinear dry friction term after the engineering treatment in step 3. The equivalent viscous damping coefficient Elastic force term of hinge motion with gap The corresponding equivalent stiffness coefficient Fixed-position elastic force term with gap The corresponding equivalent stiffness coefficient in: i is the number of the i-th part of the aircraft elevator control system, i = 1, 2, 3, 4; x i is the displacement of the mass block in the i-th part of the equivalent linearized model of the aircraft elevator control system; is the velocity of the mass block in the i-th part of the equivalent linearized model of the aircraft elevator control system; u is the displacement of the front cockpit control components; M i is the normal force at the contact point of the dry friction term in the i-th part of the equivalent linearized model of the aircraft elevator control system; e i is the active position gap of the i-th part of the equivalent linearized model of the aircraft elevator control system; d i is the fixed position gap of the i-th part of the equivalent linearized model of the aircraft elevator control system; Step 5: Construct an equivalent linear model: In C i ≥e i , B i ≥d i Under the constraint condition of Equivalent stiffness coefficient And the equivalent stiffness coefficient Substituting into the equivalent dynamic model in step 1, converting the first part, the second part, the third part and the fourth part of the equivalent dynamic model obtained in step 1 into equivalent linearized models respectively; in: C i is the amplitude of the cosine function of the relative displacement between the mass block of the ith part and the mass block of the previous part of the equivalent linearized model of the aircraft elevator control system; B i is the amplitude of the cosine function of the displacement of the mass block in the i-th part of the equivalent linearized model of the aircraft elevator control system; Step 6: Construction of hysteresis operator: Step 601, based on the equivalent linearized model of the aircraft elevator control system obtained in step 5, derive and solve the amplitude-frequency characteristic control equations and the phase-frequency characteristic control equations of the first part, the second part, the third part and the fourth part, and obtain the amplitude-frequency characteristic control equation group and the phase-frequency characteristic control equation group of the aircraft elevator control system; Step 602, obtaining a hysteresis operator of the aircraft elevator control system according to the amplitude-frequency characteristic control equation group and the phase-frequency characteristic control equation group of the aircraft elevator control system obtained in step 601; Step 7: Hysteresis loop simulation analysis: Based on the amplitude-frequency characteristic control equation group and the phase-frequency characteristic control equation group of the aircraft elevator control system obtained in step 601, a simulation analysis is performed to obtain the influence of the clearance and dry friction on the hysteresis loop of the aircraft elevator control system; Step 8: Simulation analysis of rudder surface oscillation characteristics: Step 801, based on the hysteresis operator of the aircraft elevator control system obtained in step 602, a hysteresis nonlinear model of the man-machine closed-loop aircraft elevator control system is established; Step 802, according to the influence of the clearance and dry friction force on the hysteresis loop of the aircraft elevator control system obtained in step 7, by increasing the active position clearance e=[e1 e2 e3 e4] of the aircraft elevator control system or the normal force M=[M1 M2 M3 M4] of the contact point in the dry friction force, increasing the hysteresis dead zone value, and performing a control surface motion delay response analysis on the hysteresis nonlinear model under different hysteresis dead zones; Step 803, based on the control surface motion delay response analysis obtained in step 802, determine to use the hysteresis dead zone as a criterion for determining whether the aircraft elevator control system function is degraded.

4. The method for determining whether the function of an aircraft elevator control system is degraded according to claim 3, wherein: In step 5, the equivalent linearization model includes: The equivalent linearized equation for Part 1 is: The equivalent linearized equation for Part 2 is: The equivalent linearized equation for Part 3 is: The equivalent linearized equation for Part 4 is: Where: i is the number of the i-th part of the aircraft elevator control system, i = 1, 2, 3, 4; is the acceleration of the mass block in the i-th part of the equivalent linearized model of the aircraft elevator control system; The speed of the front cockpit control components; is the equivalent viscous damping coefficient of the nonlinear dry friction term of the i-th part of the equivalent linearized model of the aircraft elevator control system; is the equivalent stiffness coefficient corresponding to the elastic force term of the hinge motion with clearance in the i-th part of the equivalent linearized model of the aircraft elevator control system; is the equivalent stiffness coefficient corresponding to the fixed position elastic force term with gap in the i-th part of the equivalent linearized model of the aircraft elevator control system.

5. The method for determining whether the aircraft elevator control system function is degraded according to claim 3, wherein: In step 602, the expression of the hysteresis operator of the aircraft elevator control system is: Where: x4(t) is the displacement of the mass block of the equivalent linearized model of the rudder mechanism, which is equivalent to the deflection angle of the rudder surface of the aircraft elevator control system; is the acceleration of the mass block of the equivalent linearized model of the rudder mechanism; is the first harmonic amplitude of the relative displacement between the mass block of the equivalent linearized model of the rudder mechanism and the mass block of the equivalent linearized model of the tail motion mechanism of the fuselage; is the phase lag angle of the first harmonic of the mass block of the equivalent linearized model of the rudder mechanism; t is the actuation time of the rudder movement; u(t) is the displacement of the steering column of the front cockpit control component, and the excitation is a triangular wave; U / 2 is the amplitude of the steering column displacement; is the acceleration of the steering column displacement; In step 602, the aircraft elevator control system hysteresis operator has a finite slope, and the slope interval is [ρ1, ρ2], Where: ρ1 is the minimum value of the slope of the hysteresis operator; ρ2 is the maximum value of the slope of the hysteresis operator; In step 602, the hysteresis dead zone of the hysteresis operator of the aircraft elevator control system 6. The method for determining whether the function of an aircraft elevator control system is degraded according to claim 3, wherein: In step seven, the effects of the gap and dry friction on the hysteresis loop of the aircraft elevator control system are as follows: the combat fatigue of the aircraft elevator control system is positively correlated with the hysteresis dead zone; under the same dry friction, the larger the gap of the aircraft elevator control system, the larger the phase lag angle and the larger the hysteresis dead zone; under the same gap amount, the larger the dry friction, the more serious the phase lag and the larger the hysteresis dead zone; the simulation results also show that no matter whether the active position gap e=[e1 e2 e3 e4] or the normal force M=[M1 M2 M3 M4] of the contact point in the dry friction is increased, only one hysteresis loop appears at the origin, that is, the size, number and position of the gap have no effect on the number and position of the hysteresis loop, indicating the uniqueness of the hysteresis loop.

7. The method for determining whether the aircraft elevator control system function is degraded according to claim 3, wherein: In step 802, the different hysteresis dead zones include a step input truncation function hysteresis dead zone and a pulse function hysteresis dead zone; In step 802, the delayed response of the control surface movement is: as the hysteresis dead zone increases, the oscillation of the control surface increases, the convergence time increases, and the function of the aircraft elevator control system decreases; when the hysteresis dead zone value reaches 13.5mm, the control surface oscillates with equal amplitude, and the aircraft elevator control system loses its function.

8. The method for determining whether the aircraft elevator control system function is degraded according to claim 3, wherein: The determination method further comprises step nine; Step nine, according to the relationship between the hysteresis dead zone and the delayed response of the control surface movement obtained in step eight, based on the delayed response of the control surface movement, establish a corresponding relationship between the functional level of the aircraft elevator control system and the hysteresis dead zone interval value, and determine the functional level of the aircraft elevator control system according to the hysteresis dead zone value.

9. A method for determining whether a function of an aircraft control system is degraded, wherein the aircraft control system includes an aircraft elevator control system, characterized in that: This determination method uses the hysteresis dead zone as a determination indicator of the degradation of the aircraft control system function.

10. The method for determining aircraft control system function degradation according to claim 9, characterized in that: The method for determining that the judgment indicator is a hysteresis dead zone adopts the method for determining that the judgment indicator is a hysteresis dead zone in the method for determining the reduction in function of an aircraft elevator control system as described in any one of claims 2 to 8.

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