CN116107293A - Civil aircraft flight control system actuation loop fault diagnosis system and diagnosis method - Google Patents
Civil aircraft flight control system actuation loop fault diagnosis system and diagnosis method Download PDFInfo
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Abstract
The invention provides a fault diagnosis system and a fault diagnosis method for an actuating loop of a civil aircraft flight control system. The fault diagnosis system can realize fault prediction and fault positioning of the actuating loop. The fault diagnosis system and the diagnosis method can provide reference for aviation stock in advance, and save maintenance and replacement time. In addition, fault location provides a reference for repair of the LRU returned to the factory, so that repair efficiency can be improved. Meanwhile, the system has a fault prediction and early warning function, so that a hidden early fault can be found before the system, and related parts can be reminded to be replaced in advance, thereby enhancing the operation safety of the civil aircraft.
Description
Technical Field
The invention relates to the technical field of civil aircraft fault diagnosis, in particular to a civil aircraft flight control system actuation loop fault diagnosis system and a diagnosis method.
Background
At present, in a large-scale civil aircraft flight control system, electro-hydraulic control is largely adopted to realize the control of aircraft control surfaces, such as ten multipath electro-hydraulic control loops of a rudder, left and right ailerons, left and right elevators, a multifunctional spoiler, a ground spoiler and the like. The electro-hydraulic control circuit, also called an actuation circuit, mainly comprises a remote control unit (Remote Electronic Unit, abbreviated as REU), an electro-hydraulic servo valve (Electric Hydraulic Servo Valve, abbreviated as EHSV), an actuator, and a position sensor (Linear Variable Displacement Transducer, abbreviated as LVDT).
REU, EHSV, actuators, etc. are used as line replaceable parts (Line Replaceble Unit, LRU for short) that can be replaced if a fault occurs during the course of the aircraft. The existing fault judging method of the replaceable component mainly comprises the modes of visual diagnosis, diagnosis that an actuator is not in place by REU according to the feedback position of LVDT, self-detection in REU machine, EHSV working current drift and the like.
The currently used fault diagnosis system and the fault diagnosis method thereof, although meeting the basic fault diagnosis requirement of the operation of the aircraft, still have the following defects:
firstly, the current fault diagnosis method of the flight control electrohydraulic servo actuation circuit is mainly used for diagnosing the existing faults and can not diagnose the fault symptoms, namely, predicting the prior faults.
Second, even if a fault has occurred, no specific possible cause of the fault can be given for the fault phenomenon. For example, the failure of the actuator in place may be caused by the actuator itself or EHSV, if only the feedback position of the LVDT is judged to be different from the instruction, the failure cannot be located in a specific component, and there is generally a relatively hidden early failure, such as mechanical wear of the EHSV, before the failure of the actuator in place occurs, which cannot be diagnosed in advance by using the diagnostic method in the prior art.
For this reason, there is a need to propose a civil aircraft flight control system actuation circuit fault diagnosis system and a diagnosis method thereof that can implement fault prediction (i.e., prompt that a problem has occurred in a related component before a fault occurs) and implement fault localization (i.e., possible fault causes can be given by fault manifestations).
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a fault diagnosis system and a fault diagnosis method for an actuating loop of a civil aircraft flight control system, which can realize fault prediction and fault positioning of the actuating loop. The LRU service condition can be obtained in advance through fault prediction, so that references are provided for aviation stock in advance, and maintenance and replacement time is saved. In addition, fault location provides a reference for repair of the LRU returned to the factory, so that repair efficiency can be improved. Meanwhile, the system has a fault prediction and early warning function, so that a hidden early fault can be found before the system, and related parts can be reminded to be replaced in advance, thereby enhancing the operation safety of the civil aircraft.
In order to achieve the above purpose, the present invention provides the following technical solutions: a civil aircraft flight control system actuation circuit fault diagnosis system comprising:
the signal acquisition module is used for periodically and continuously acquiring a position signal of the actuator, a pressure signal of the actuator and a control signal of a corresponding remote control unit;
The actuating circuit dynamic characteristic identification module is used for identifying the dynamic characteristic of the actuating circuit according to the position signals of the actuators in a plurality of sampling periods and the control signals of the corresponding remote control units; separating dynamic characteristics of the actuating circuit by adopting a separation method to separate undamped natural frequency of the actuating circuit and damping ratio of the actuating circuit;
and the actuating loop fault judging module is used for comparing the undamped natural frequency of the separated actuating loop with an actuating loop undamped natural frequency threshold preset in the actuating loop fault judging module, and outputting the actuating loop fault when the undamped natural frequency of the actuating loop exceeds the actuating loop undamped natural frequency threshold.
The preferred technical scheme is that the civil aircraft flight control system actuation loop fault diagnosis system further comprises:
the output flow calculating module is used for calculating the speed of the actuator and the output flow of the electrohydraulic servo valve by adopting an optimal estimation method according to the position signal of the actuator and the pressure signal of the actuator;
the curve equation fitting module is used for fitting out the flow gain of the electrohydraulic servo valve and the curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; according to the curve equation, calculating a control signal of a corresponding remote control unit when the electrohydraulic servo valve has zero flow;
And the electrohydraulic servo valve fault judging module is used for comparing the control signal of the corresponding remote control unit when the electrohydraulic servo valve zero flow is calculated with the electrohydraulic servo valve zero flow signal threshold value preset in the electrohydraulic servo valve fault judging module, and outputting the electrohydraulic servo valve zero drift overrun when the electrohydraulic servo valve zero flow signal threshold value is exceeded.
The preferred technical scheme is that the civil aircraft flight control system actuation loop fault diagnosis system further comprises:
the output flow calculating module is used for calculating the speed of the actuator and the output flow of the electrohydraulic servo valve by adopting an optimal estimation method according to the position signal of the actuator and the pressure signal of the actuator;
the curve equation fitting module is used for fitting out the flow gain of the electrohydraulic servo valve and the curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; according to the curve equation, calculating a control signal of a corresponding remote control unit when the electrohydraulic servo valve has zero flow;
The electrohydraulic servo valve dynamic characteristic identification module is used for identifying the dynamic characteristic of the electrohydraulic servo valve according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; separating dynamic characteristics of the electro-hydraulic servo valve by adopting a separation method to separate undamped natural frequency of the electro-hydraulic servo valve and damping ratio of the electro-hydraulic servo valve;
the electrohydraulic servo valve fault judging module is used for comparing the control signal of the corresponding remote control unit when the electrohydraulic servo valve zero flow is calculated with the electrohydraulic servo valve zero flow signal threshold value preset in the electrohydraulic servo valve fault judging module, and outputting the electrohydraulic servo valve zero drift overrun when the electrohydraulic servo valve zero flow signal threshold value is exceeded; comparing the undamped natural frequency of the separated electrohydraulic servo valve with an undamped natural frequency threshold of the electrohydraulic servo valve preset in the electrohydraulic servo valve fault judging module, and outputting the clamping stagnation of the electrohydraulic servo valve when the undamped natural frequency threshold of the electrohydraulic servo valve is exceeded.
The preferred technical scheme is that the civil aircraft flight control system actuation loop fault diagnosis system further comprises:
the output flow calculating module is used for calculating the speed of the actuator and the output flow of the electrohydraulic servo valve by adopting an optimal estimation method according to the position signal of the actuator and the pressure signal of the actuator;
The curve equation fitting module is used for fitting out the flow gain of the electrohydraulic servo valve and the curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; according to the curve equation, calculating a control signal of a corresponding remote control unit when the electrohydraulic servo valve has zero flow;
the electrohydraulic servo valve dynamic characteristic identification module is used for identifying the dynamic characteristic of the electrohydraulic servo valve according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; separating dynamic characteristics of the electro-hydraulic servo valve by adopting a separation method to separate undamped natural frequency of the electro-hydraulic servo valve and damping ratio of the electro-hydraulic servo valve;
the electrohydraulic servo valve fault judging module is used for comparing the control signal of the corresponding remote control unit when the electrohydraulic servo valve zero flow is calculated with the electrohydraulic servo valve zero flow signal threshold value preset in the electrohydraulic servo valve fault judging module, and outputting the electrohydraulic servo valve zero drift overrun when the electrohydraulic servo valve zero flow signal threshold value is exceeded; comparing the undamped natural frequency of the separated electrohydraulic servo valve with an undamped natural frequency threshold of the electrohydraulic servo valve preset in the electrohydraulic servo valve fault judging module, and outputting the clamping stagnation of the electrohydraulic servo valve when the undamped natural frequency threshold of the electrohydraulic servo valve is exceeded; and comparing the damping ratio of the separated electrohydraulic servo valve with an electrohydraulic servo valve damping ratio threshold value preset in an electrohydraulic servo valve fault judging module, and outputting electrohydraulic servo valve clamping stagnation when the damping ratio threshold value of the electrohydraulic servo valve is exceeded.
The preferred technical scheme is that the civil aircraft flight control system actuation loop fault diagnosis system further comprises:
and the actuator fault judging module is used for outputting actuator clamping stagnation when the actuating loop fault is output by the actuating loop fault judging module, and the electro-hydraulic servo valve fault judging module does not output the zero drift overrun of the electro-hydraulic servo valve and does not output the electro-hydraulic servo valve clamping stagnation.
According to the preferable technical scheme, the fault diagnosis system of the actuation circuit of the civil aircraft flight control system is arranged in a remote control unit of the actuation circuit.
Still another object of the present invention is to provide a method for diagnosing faults of an actuation circuit of a civil aircraft flight control system, comprising the following steps in sequence:
step one, periodically and continuously collecting position signals of an actuator through a position sensor, correspondingly periodically and continuously collecting pressure signals of the actuator through a pressure sensor, and obtaining control signals of a corresponding remote control unit;
step two, identifying dynamic characteristics of an actuating loop according to position signals of a plurality of sampling period actuators and control signals of corresponding remote control units; separating dynamic characteristics of the actuating circuit by adopting a separation method to separate undamped natural frequency of the actuating circuit and damping ratio of the actuating circuit;
And thirdly, comparing the undamped natural frequency of the separated actuating circuit and the damping ratio of the separated actuating circuit with the undamped natural frequency of the actuating circuit calibrated by a factory and the damping ratio of the actuating circuit calibrated by the factory respectively to obtain the health condition of the actuating circuit.
In the third step, the specific process of obtaining the health condition of the actuation circuit is as follows:
and when the value change between the undamped natural frequency of the separated actuating circuit and the undamped natural frequency of the actuating circuit calibrated by the factory exceeds 40 percent or when the value change between the damping ratio of the separated actuating circuit and the damping ratio of the actuating circuit calibrated by the factory exceeds 40 percent, the actuating circuit fault is obtained.
The preferred technical scheme further comprises the following steps with sequence after the third step:
calculating the speed of the actuator and the output flow of the electrohydraulic servo valve by adopting an optimal estimation method according to the position signal of the actuator and the pressure signal of the actuator;
fitting a curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; according to the curve equation, calculating a control signal of a corresponding remote control unit when the electrohydraulic servo valve has zero flow by adopting a dichotomy;
And step six, comparing the calculated control signal of the corresponding remote control unit in the zero flow of the electrohydraulic servo valve with a factory calibrated electrohydraulic servo valve zero flow signal to obtain the health condition of the electrohydraulic servo valve.
In the sixth step, the specific process of obtaining the health condition of the electro-hydraulic servo valve is as follows:
when the calculated value change between the control signal of the corresponding remote control unit and the factory calibrated zero flow signal of the electrohydraulic servo valve exceeds 10%, the zero drift overrun of the electrohydraulic servo valve is obtained.
In the preferred technical scheme, in the second step,
according to the position signals of the actuators in a plurality of sampling periods and the control signals of the corresponding remote control units, the dynamic characteristics of the actuating loop are identified as follows:
wherein ,
is the natural frequency of the damping-free of the actuation circuit, < ->
For the damping ratio of the actuation circuit, +.>
Lawster's transformation of the position signal for the actuator, < >>
Law's transformation of control signals for a remote control unit,/->
Is a Laplacian operator;
the separation method adopts inverse transformation from Z domain to S domain to separate out undamped natural frequency of the actuating loop
Damping ratio of the actuating circuit +. >
。
In the second step, the undamped natural frequency of the actuating loop is separated by adopting the inverse transformation from the Z domain to the S domain
Damping ratio of the actuating circuit +.>
The specific process of (2) is as follows:
first, the dynamic characteristics of the actuation circuit are solved
A corresponding discrete equation root Z;
and converting the discrete equation root Z into a continuous domain root S, wherein the conversion formula is as follows:
wherein T is the sampling interval between sampling periods;
finally, the undamped natural frequency of the actuating loop can be obtained through the continuous domain root S
Damping ratio of the actuating circuit +.>
。
In the preferred embodiment, in the second step, the dynamic characteristic of the actuation circuit
The corresponding discrete equation is:
wherein ,
sampling period sequence number; />
Is the coefficient to be identified; />
The number of poles; />
The number of the zero points; />
Delay beats; />
Position signal representing actuator->
Is->
Position signal of actuator corresponding to each sampling period, < +.>
Is->
Position signals of actuators corresponding to the sampling periods, and the like;
control signal representing the corresponding remote control unit, < >>
Is->
Control signals of remote control units corresponding to the sampling periods, and so on,/and so on>
Is->
And a control signal of the remote control unit corresponding to the sampling period.
According to the preferred technical scheme, the optimal estimation method adopted in the fourth step is a Kalman filtering method of a correction coefficient, and the speed of the actuator and the output flow of the electrohydraulic servo valve are calculated, wherein the specific process is as follows:
first, the flow formula of the electrohydraulic servo valve is as follows:
the forward output flow of the electrohydraulic servo valve is as follows:
wherein ,
for the positive output flow of electrohydraulic servo valve, < >>
Is the flow coefficient; />
Is the density of the liquid; />
For the supply pressure>
For positive output pressure of electrohydraulic servo valve, < >>
For the area of the rod cavity of the actuator, +.>
Is the speed of the actuator;
the negative output flow of the electrohydraulic servo valve is as follows:
wherein ,
for the negative output flow of electrohydraulic servo valve, +.>
Is the flow coefficient; />
Is the density of the liquid; />
For the supply pressure>
For negative output pressure of electrohydraulic servo valve, +.>
Is the rodless cavity area of the actuator, +.>
Is the speed of the actuator;
secondly, linearizing the flow formula of the electrohydraulic servo valve by using a Taylor formula to obtain:
forward output flow of electrohydraulic servo valve:
negative output flow of electrohydraulic servo valve:
wherein ,
for forward flow gain, +.>
In the form of increments of the control signal of the remote control unit, < >>
Is a positive pressure gain- >
The positive output pressure of the electrohydraulic servo valve is increased; />
For negative flow gain, +.>
For negative pressure gain, +.>
Negative direction of electrohydraulic servo valveAn incremental form of output pressure;
again, from the actuator pressure model:
wherein ,
is the volume elastic modulus of oil liquid, +.>
Is the rodless cavity volume of the actuator, +.>
For the rod chamber volume of the actuator, +.>
For the position signal of the actuator,>
for the leakage coefficient of the rodless cavity of the actuator, +.>
For actuators with rod chamber leakage coefficient +.>
For the sampling period +.>
Is->
First derivative with respect to time;
the motion model of the actuator is established as follows:
wherein ,
representative actuatorMass of the middle sports piece->
Representing the motion damping coefficient of a moving part in the actuator,
representing the elastic coefficient of a moving part in the actuator;
the state space model of the actuation circuit is built as follows:
wherein ,
is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time;
Finally, after a prediction process noise covariance matrix and a measurement process covariance matrix in Kalman filtering are set, a complete Kalman filtering model is obtained, kalman filtering is realized, and therefore the speed of the actuator and the output flow of the electrohydraulic servo valve are calculated.
In the fifth step, the output flow of the electrohydraulic servo valve and the control signal of the corresponding remote control unit are calculated according to a plurality of sampling periods, the flow gain of the electrohydraulic servo valve is fitted, and a curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit adopts a least square method, and the specific curve equation is as follows:
wherein ,
for the output flow of electrohydraulic servo valve, +.>
For the control signal of the remote control unit, +.>
For the flow gain of electrohydraulic servo valve, +.>
Is constant.
Still another object of the present invention is to provide a fault diagnosis method for an actuation circuit of a civil aircraft flight control system, comprising the steps of:
calculating the speed of the actuator and the output flow of the electrohydraulic servo valve by adopting an optimal estimation method according to the position signal of the actuator and the pressure signal of the actuator;
fitting a curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; according to the curve equation, calculating a control signal of a corresponding remote control unit when the electrohydraulic servo valve has zero flow;
Step six, identifying the dynamic characteristics of the electrohydraulic servo valve according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; separating dynamic characteristics of the electro-hydraulic servo valve by adopting a separation method to separate undamped natural frequency of the electro-hydraulic servo valve and damping ratio of the electro-hydraulic servo valve;
and seventhly, comparing the calculated control signal of the corresponding remote control unit when the electrohydraulic servo valve is at zero flow, the undamped natural frequency of the separated electrohydraulic servo valve and the damping ratio of the separated electrohydraulic servo valve with the zero flow signal of the factory calibrated electrohydraulic servo valve, the undamped natural frequency of the factory calibrated electrohydraulic servo valve and the damping ratio of the factory calibrated electrohydraulic servo valve respectively to obtain the health condition of the electrohydraulic servo valve.
In the seventh step, the preferred technical scheme obtains the specific process of the health condition of the electro-hydraulic servo valve as follows:
when the calculated value change between the control signal of the corresponding remote control unit and the factory calibrated zero flow signal of the electrohydraulic servo valve exceeds 10%, obtaining zero drift overrun of the electrohydraulic servo valve;
When the value change between the undamped natural frequency of the separated electrohydraulic servo valve and the undamped natural frequency of the electrohydraulic servo valve calibrated by a factory exceeds 40%, the clamping stagnation of the electrohydraulic servo valve is obtained;
and when the value change between the damping ratio of the separated electrohydraulic servo valve and the damping ratio of the electrohydraulic servo valve calibrated by a factory exceeds 40%, the clamping stagnation of the electrohydraulic servo valve is obtained.
The preferable technical scheme further comprises the following steps:
step eight: and when the action loop fault is obtained in the third step, and the electro-hydraulic servo zero drift overrun is not obtained in the seventh step, the electro-hydraulic servo valve clamping stagnation is not obtained, and the actuator clamping stagnation is obtained.
In the preferred technical scheme, in the second step,
according to the position signals of the actuators in a plurality of sampling periods and the control signals of the corresponding remote control units, the dynamic characteristics of the actuating loop are identified as follows:
wherein ,
is the natural frequency of the damping-free of the actuation circuit, < ->
For the damping ratio of the actuation circuit, +.>
Lawster's transformation of the position signal for the actuator, < >>
Law's transformation of control signals for a remote control unit,/->
Is a Laplacian operator; />
The separation method adopts inverse transformation from Z domain to S domain to separate out undamped natural frequency of the actuating loop 
Damping ratio of the actuating circuit +.>
。
In the second step, the undamped natural frequency of the actuating loop is separated by adopting the inverse transformation from the Z domain to the S domain
Damping ratio of the actuating circuit +.>
The specific process of (2) is as follows:
first, the dynamic characteristics of the actuation circuit are solved
A corresponding discrete equation root Z;
and converting the discrete equation root Z into a continuous domain root S, wherein the conversion formula is as follows:
wherein T is the sampling interval between sampling periods;
finally, the undamped natural frequency of the actuating loop can be obtained through the continuous domain root S
Damping ratio of the actuating circuit +.>
。
In the preferred embodiment, in the second step, the dynamic characteristic of the actuation circuit
The corresponding discrete equation is:
wherein ,
sampling period sequence number; />
Is the coefficient to be identified; />
The number of poles; />
The number of the zero points; />
Delay beats; />
Position signal representing actuator->
Is->
Position signal of actuator corresponding to each sampling period, < +.>
Is->
Position signals of actuators corresponding to the sampling periods, and the like;
control signal representing the corresponding remote control unit, < >>
Is->
Control signals of remote control units corresponding to the sampling periods, and so on,/and so on >
Is->
And a control signal of the remote control unit corresponding to the sampling period.
According to the preferred technical scheme, the optimal estimation method adopted in the fourth step is a Kalman filtering method of a correction coefficient, and the speed of the actuator and the output flow of the electrohydraulic servo valve are calculated, wherein the specific process is as follows:
first, the flow formula of the electrohydraulic servo valve is as follows:
the forward output flow of the electrohydraulic servo valve is as follows:
wherein ,
for the positive output flow of electrohydraulic servo valve, < >>
Is the flow coefficient; />
Is the density of the liquid; />
For the supply pressure>
For positive output pressure of electrohydraulic servo valve, < >>
For the area of the rod cavity of the actuator, +.>
Is the speed of the actuator;
the negative output flow of the electrohydraulic servo valve is as follows:
wherein ,
for the negative output flow of electrohydraulic servo valve, +.>
Is the flow coefficient; />
Is the density of the liquid; />
For the supply pressure>
For negative output pressure of electrohydraulic servo valve, +.>
Is the rodless cavity area of the actuator, +.>
Is the speed of the actuator;
secondly, linearizing the flow formula of the electrohydraulic servo valve by using a Taylor formula to obtain:
forward output flow of electrohydraulic servo valve:
negative output flow of electrohydraulic servo valve:
wherein ,
for forward flow gain, +. >
In the form of increments of the control signal of the remote control unit, < >>
Is forward pressureForce gain (I)>
The positive output pressure of the electrohydraulic servo valve is increased; />
For negative flow gain, +.>
For negative pressure gain, +.>
An increment form of negative output pressure of the electrohydraulic servo valve;
again, from the actuator pressure model:
wherein ,
is the volume elastic modulus of oil liquid, +.>
Is the rodless cavity volume of the actuator, +.>
For the rod chamber volume of the actuator, +.>
For the position signal of the actuator,>
for the leakage coefficient of the rodless cavity of the actuator, +.>
The rod cavity leakage coefficient is set for the actuator,
for the sampling period +.>
Is->
First derivative with respect to time;
the motion model of the actuator is established as follows:
wherein ,
representing the mass of the moving part in the actuator, +.>
Representing the motion damping coefficient of a moving part in the actuator,
representing the elastic coefficient of a moving part in the actuator;
the state space model of the actuation circuit is built as follows:
wherein ,
is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time;
finally, after a prediction process noise covariance matrix and a measurement process covariance matrix in Kalman filtering are set, a complete Kalman filtering model is obtained, kalman filtering is realized, and therefore the speed of the actuator and the output flow of the electrohydraulic servo valve are calculated.
In the fifth step, the output flow of the electrohydraulic servo valve and the control signal of the corresponding remote control unit are calculated according to a plurality of sampling periods, the flow gain of the electrohydraulic servo valve is fitted, and a curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit adopts a least square method, and the specific curve equation is as follows:
wherein ,
for the output flow of electrohydraulic servo valve, +.>
For the control signal of the remote control unit, +.>
For the flow gain of electrohydraulic servo valve, +.>
Is constant.
In the sixth step, according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit, the dynamic characteristics of the electrohydraulic servo valve are identified as follows:
wherein ,
Is the undamped natural frequency of the electrohydraulic servo valve, < ->
Is the damping ratio of electrohydraulic servo valve, +.>
Law's transformation of the output flow of the electrohydraulic servo valve,>
law's transformation of control signals for a remote control unit,/->
Is a Laplacian operator;
the separation method adopts inverse transformation from Z domain to S domain to separate out undamped natural frequency of electrohydraulic servo valve
Damping ratio with electrohydraulic servo valve>
。/>
In the sixth step, the undamped natural frequency of the electrohydraulic servo valve is separated by adopting the inverse transformation from the Z domain to the S domain
Damping ratio with electrohydraulic servo valve>
The specific process of (2) is as follows:
first, solving the dynamic characteristics of electrohydraulic servo valve
A corresponding discrete equation root Z;
and converting the discrete equation root Z into a continuous domain root S, wherein the conversion formula is as follows:
wherein T is the sampling interval between sampling periods;
finally, the undamped natural frequency of the electrohydraulic servo valve can be obtained through the continuous domain root S
Damping ratio with electrohydraulic servo valve>
。
In the sixth step, the dynamic characteristics of the electrohydraulic servo valve
The corresponding discrete equation is:
wherein ,
sampling period sequence number; />
Is the coefficient to be identified; />
The number of poles; />
The number of the zero points; / >
Delay beats; />
Position signal representing actuator->
Is->
Position signal of actuator corresponding to each sampling period, < +.>
Is->
Position signals of actuators corresponding to the sampling periods, and the like;
control signal representing the corresponding remote control unit, < >>
Is->
Control signal of remote control unit corresponding to each sampling periodNumber, and so on, the->
Is->
And a control signal of the remote control unit corresponding to the sampling period.
Still another object of the present invention is to provide a fault diagnosis method for an actuation circuit of a civil aircraft flight control system, comprising the steps of:
step one, periodically and continuously collecting position signals of an actuator through a position sensor, correspondingly periodically and continuously collecting pressure signals of the actuator through a pressure sensor, and obtaining control signals of a corresponding remote control unit;
calculating the speed of the actuator and the output flow of the electrohydraulic servo valve by adopting an optimal estimation method according to the position signal of the actuator and the pressure signal of the actuator;
fitting a curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; according to the curve equation, calculating a control signal of a corresponding remote control unit when the electrohydraulic servo valve has zero flow;
Step four, identifying the dynamic characteristics of the electrohydraulic servo valve according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; separating dynamic characteristics of the electro-hydraulic servo valve by adopting a separation method to separate undamped natural frequency of the electro-hydraulic servo valve and damping ratio of the electro-hydraulic servo valve;
and fifthly, comparing the calculated control signals of the corresponding remote control units, the undamped natural frequency of the separated electrohydraulic servo valve and the damping ratio of the separated electrohydraulic servo valve with the zero flow signals of the factory calibrated electrohydraulic servo valve, the undamped natural frequency of the factory calibrated electrohydraulic servo valve and the damping ratio of the factory calibrated electrohydraulic servo valve to obtain the health condition of the electrohydraulic servo valve.
In the fifth step, the specific process of obtaining the health condition of the electro-hydraulic servo valve is as follows:
when the calculated value change between the control signal of the corresponding remote control unit and the factory calibrated zero flow signal of the electrohydraulic servo valve exceeds 10%, obtaining zero drift overrun of the electrohydraulic servo valve;
when the value change between the undamped natural frequency of the separated electrohydraulic servo valve and the undamped natural frequency of the electrohydraulic servo valve calibrated by a factory exceeds 40%, the clamping stagnation of the electrohydraulic servo valve is obtained;
And when the value change between the damping ratio of the separated electrohydraulic servo valve and the damping ratio of the electrohydraulic servo valve calibrated by a factory exceeds 40%, the clamping stagnation of the electrohydraulic servo valve is obtained.
The preferable technical scheme further comprises the following steps:
step six, identifying dynamic characteristics of the actuating loop according to position signals of a plurality of sampling period actuators and control signals of corresponding remote control units; separating dynamic characteristics of the actuating circuit by adopting a separation method to separate undamped natural frequency of the actuating circuit and damping ratio of the actuating circuit;
and step seven, comparing the undamped natural frequency of the separated actuating circuit and the damping ratio of the separated actuating circuit with the undamped natural frequency of the actuating circuit calibrated by a factory and the damping ratio of the actuating circuit calibrated by the factory respectively to obtain the health condition of the actuating circuit.
In the preferred technical scheme, in the step seven, the specific process of obtaining the health condition of the actuation circuit is as follows:
and when the value change between the undamped natural frequency of the separated actuating circuit and the undamped natural frequency of the actuating circuit calibrated by the factory exceeds 40 percent or when the value change between the damping ratio of the separated actuating circuit and the damping ratio of the actuating circuit calibrated by the factory exceeds 40 percent, the actuating circuit fault is obtained.
The preferable technical scheme further comprises the following steps:
and step eight, when the electro-hydraulic servo zero drift overrun is not obtained in the step five, the electro-hydraulic servo valve clamping stagnation is not obtained, and the actuating loop fault is obtained in the step seven, the actuator clamping stagnation is obtained.
According to the preferred technical scheme, the optimal estimation method adopted in the second step is a Kalman filtering method of a correction coefficient, and the speed of the actuator and the output flow of the electrohydraulic servo valve are calculated, wherein the specific process is as follows:
first, the flow formula of the electrohydraulic servo valve is as follows:
the forward output flow of the electrohydraulic servo valve is as follows:
wherein ,
for the positive output flow of electrohydraulic servo valve, < >>
Is the flow coefficient; />
Is the density of the liquid; />
For the supply pressure>
For positive output pressure of electrohydraulic servo valve, < >>
For the area of the rod cavity of the actuator, +.>
Is the speed of the actuator;
the negative output flow of the electrohydraulic servo valve is as follows:
wherein ,
for the negative output flow of electrohydraulic servo valve, +.>
Is the flow coefficient; />
Is the density of the liquid; />
For the supply pressure>
For negative output pressure of electrohydraulic servo valve, +.>
Is the rodless cavity area of the actuator, +.>
Is the speed of the actuator;
secondly, linearizing the flow formula of the electrohydraulic servo valve by using a Taylor formula to obtain:
Forward output flow of electrohydraulic servo valve:
negative output flow of electrohydraulic servo valve:
wherein ,
for forward flow gain, +.>
In the form of increments of the control signal of the remote control unit, < >>
Is a positive pressure gain->
The positive output pressure of the electrohydraulic servo valve is increased; />
For negative flow gain, +.>
For negative pressure gain, +.>
An increment form of negative output pressure of the electrohydraulic servo valve;
again, from the actuator pressure model:
wherein ,
is the volume elastic modulus of oil liquid, +.>
Is the rodless cavity volume of the actuator, +.>
For the rod chamber volume of the actuator, +.>
For the position signal of the actuator,>
for the leakage coefficient of the rodless cavity of the actuator, +.>
The rod cavity leakage coefficient is set for the actuator,
for the sampling period +.>
Is->
First derivative with respect to time;
the motion model of the actuator is established as follows:
wherein ,
representing the mass of the moving part in the actuator, +.>
Representing the motion damping coefficient of a moving part in the actuator,
representing the elastic coefficient of a moving part in the actuator;
the state space model of the actuation circuit is built as follows:
wherein ,
is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time, < > >
Is->
First derivative with respect to time; />
finally, after a prediction process noise covariance matrix and a measurement process covariance matrix in Kalman filtering are set, a complete Kalman filtering model is obtained, kalman filtering is realized, and therefore the speed of the actuator and the output flow of the electrohydraulic servo valve are calculated.
According to the preferred technical scheme, in the third step, according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit, the flow gain of the electrohydraulic servo valve is fitted, and a curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit adopts a least square method, and the specific curve equation is as follows:
wherein ,
for the output flow of electrohydraulic servo valve, +.>
For the control signal of the remote control unit, +.>
For the flow gain of electrohydraulic servo valve, +.>
Is constant.
In the fourth step, the dynamic characteristics of the electrohydraulic servo valve are identified as follows according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit:
wherein ,
is the undamped natural frequency of the electrohydraulic servo valve, < ->
Is the damping ratio of electrohydraulic servo valve, +.>
Law's transformation of the output flow of the electrohydraulic servo valve,>
law's transformation of control signals for a remote control unit,/->
Is a Laplacian operator;
the separation method adopts inverse transformation from Z domain to S domain to separate out undamped natural frequency of electrohydraulic servo valve
And electrohydraulic servoDamping ratio of valve->
。
In the fourth step, the undamped natural frequency of the electrohydraulic servo valve is separated by adopting the inverse transformation from the Z domain to the S domain
Damping ratio with electrohydraulic servo valve>
The specific process of (2) is as follows:
first, solving the dynamic characteristics of electrohydraulic servo valve
A corresponding discrete equation root Z;
and converting the discrete equation root Z into a continuous domain root S, wherein the conversion formula is as follows:
wherein T is the sampling interval between sampling periods;
finally, the undamped natural frequency of the electrohydraulic servo valve can be obtained through the continuous domain root S
Damping ratio with electrohydraulic servo valve>
。
In the fourth step, the dynamic characteristics of the electrohydraulic servo valve
The corresponding discrete equation is:
wherein ,
sampling period sequence number; />
Is the coefficient to be identified; />
The number of poles; / >
The number of the zero points; />
Delay beats; />
Position signal representing actuator->
Is->
Position signal of actuator corresponding to each sampling period, < +.>
Is->
Position signals of actuators corresponding to the sampling periods, and the like;
control signal representing the corresponding remote control unit, < >>
Is->
Remote corresponding to each sampling periodControl signals of the control unit, and so on, +.>
Is->
And a control signal of the remote control unit corresponding to the sampling period.
In the sixth step, according to the position signals of the actuators in the multiple sampling periods and the control signals of the corresponding remote control units, the dynamic characteristics of the actuation circuit are identified as follows:
wherein ,
is the natural frequency of the damping-free of the actuation circuit, < ->
For the damping ratio of the actuation circuit, +.>
Lawster's transformation of the position signal for the actuator, < >>
Law's transformation of control signals for a remote control unit,/->
Is a Laplacian operator;
the separation method adopts inverse transformation from Z domain to S domain to separate out undamped natural frequency of the actuating loop
Damping ratio of the actuating circuit +.>
。
Preferred technical scheme, the stepsSixth, the undamped natural frequency of the actuating loop is separated by adopting the inverse transformation from Z domain to S domain 
Damping ratio of the actuating circuit +.>
The specific process of (2) is as follows:
first, the dynamic characteristics of the actuation circuit are solved
A corresponding discrete equation root Z;
and converting the discrete equation root Z into a continuous domain root S, wherein the conversion formula is as follows:
wherein T is the sampling interval between sampling periods;
finally, the undamped natural frequency of the actuating loop can be obtained through the continuous domain root S
Damping ratio of the actuating circuit +.>
。
In the sixth step, the dynamic characteristics of the actuation circuit
The corresponding discrete equation is:
wherein ,
sampling period sequence number; />
Is the coefficient to be identified; />
The number of poles; />
The number of the zero points; />
Delay beats; />
Position signal representing actuator->
Is->
Position signal of actuator corresponding to each sampling period, < +.>
Is->
Position signals of actuators corresponding to the sampling periods, and the like;
control signal representing the corresponding remote control unit, < >>
Is->
Control signals of remote control units corresponding to the sampling periods, and so on,/and so on>
Is->
And a control signal of the remote control unit corresponding to the sampling period.
Compared with the prior art, the system and the method for diagnosing the fault of the actuation loop of the civil aircraft flight control system have the beneficial effects that:
1. The invention can realize the fault prediction and fault positioning of the actuating loop under the condition of not changing the structure of the actuating loop of the existing flight control system.
2. According to the invention, a motion model of the actuator is established through the existing position sensor of the actuating loop, control signals of the remote control unit and the pressure sensor according to the liquid continuity principle and through the relation between the speed of the actuator and the liquid flow, a Kalman filtering model of a correction coefficient is utilized, and the speed of the actuator and the output flow of the electrohydraulic servo valve are mutually verified and solved by adopting an optimal estimation method. The method can ensure the solving precision of the speed of the actuator and the calculating precision of the output flow of the electrohydraulic servo valve, further ensure the accuracy of a fitted curve equation, flow gain and a calculated control signal corresponding to zero flow, and ensure the accuracy of fault diagnosis.
3. The LRU service condition can be obtained in advance through fault prediction, so that references are provided for aviation stock in advance, and maintenance and replacement time is saved.
4. The invention has the fault positioning function, can provide reference for the repair of the LRU returned to the factory through fault positioning, and can improve the repair efficiency.
5. By continuous periodic monitoring, the invention can discover hidden early faults before the present, and remind the replacement of related parts in advance, thereby enhancing the operation safety of the civil aircraft.
6. The fault diagnosis system of the actuation circuit of the civil aircraft flight control system is built in a remote control unit of the actuation circuit. By adopting the form of being built in a remote control unit of the actuating circuit, the fault prediction and the fault positioning of the actuating circuit can be realized under the condition that the structure of the actuating circuit of the existing flight control system is not changed by utilizing a position sensor and a pressure sensor of the actuating circuit.
7. Firstly, the dynamic characteristic of the actuating loop can be established by utilizing the relation between the position sensor and the control signal, and the health condition of the actuating loop can be judged. If the actuating circuit has a problem, the positioning can be continued to judge whether the electrohydraulic servo valve has a fault. Of course, if the actuating loop judges that the actuating loop is free of problems, the actuating loop can also continuously judge whether the electro-hydraulic servo valve has hidden trouble, for example, if the actuating loop possibly has zero drift overrun (even if the actuating loop does not judge the fault at the moment, if the zero drift overrun occurs), relevant personnel can be timely reminded to prepare for overhauling the electro-hydraulic servo valve, and even spare parts are timely prepared for replacement. The invention can find potential hidden trouble and greatly increase the safety of airplane shipping.
8. The invention not only can timely find out various fault hidden dangers of the actuating loop, but also can carry out classified reminding on the various fault hidden dangers, thereby improving the working efficiency of the maintainer.
Drawings
FIG. 1 is a schematic diagram of the overall principle of the actuation circuit of the present invention;
FIG. 2 is a schematic diagram of the system architecture of a civil aircraft flight control system actuation circuit fault diagnosis system according to the present invention;
FIG. 3 is a graph showing the fit of a curve equation between the output flow of the electro-hydraulic servo valve and the control signal of the remote control unit in the present invention;
FIG. 4 is a schematic diagram of operation of a failure diagnosis system for an actuation circuit of a civil aircraft flight control system according to embodiment 1 of the present invention;
FIG. 5 is a schematic diagram of operation of a failure diagnosis system for an actuation circuit of a civil aircraft flight control system according to embodiment 2 of the present invention;
fig. 6 is a working schematic diagram of an actuation circuit fault diagnosis system of a civil aircraft flight control system according to embodiment 3 of the present invention.
Description of the embodiments
As shown in fig. 1, the civil aircraft flight control system actuation circuit comprises: remote control unit (Remote Electronic Unit, REU), electrohydraulic servo valve (Electric Hydraulic Servo Valve, EHSV), actuator, and position sensor (Linear Variable DisplacementTransducer, abbreviated LVDT). The remote control unit REU sends a control signal
Is sent to an electrohydraulic servo valve EHSV which will supply oil pressure +. >
The position sensor LVDT converts the position signal of the actuator into a driving force for controlling the actuator>
Transmitting the pressure signals to a remote control unit REU, respectively transmitting the rodless cavity pressure P1 and the rod cavity pressure P2 of the actuator to the remote control unit REU by the pressure sensor, and outputting a control signal +.>
And correcting the position of the actuator in real time to form closed-loop control.
As shown in fig. 2, the system for diagnosing faults of an actuation circuit of a civil aircraft flight control system of the present invention comprises:
the signal acquisition module is used for periodically and continuously acquiring a position signal of the actuator, a pressure signal of the actuator and a control signal of a corresponding remote control unit;
the actuating circuit dynamic characteristic identification module is used for identifying the dynamic characteristic of the actuating circuit according to the position signals of the actuators in a plurality of sampling periods and the control signals of the corresponding remote control units; separating dynamic characteristics of the actuating circuit by adopting a separation method to separate undamped natural frequency of the actuating circuit and damping ratio of the actuating circuit;
the actuating circuit fault judging module is used for comparing the undamped natural frequency of the separated actuating circuit with an actuating circuit undamped natural frequency threshold preset in the actuating circuit fault judging module, and outputting an actuating circuit fault when the undamped natural frequency of the actuating circuit exceeds the actuating circuit undamped natural frequency threshold;
The output flow calculating module is used for calculating the speed of the actuator and the output flow of the electrohydraulic servo valve by adopting an optimal estimation method according to the position signal of the actuator and the pressure signal of the actuator;
the curve equation fitting module is used for fitting out the flow gain of the electrohydraulic servo valve and the curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; according to the curve equation, calculating a control signal of a corresponding remote control unit when the electrohydraulic servo valve has zero flow by adopting a dichotomy;
the electrohydraulic servo valve dynamic characteristic identification module is used for identifying the dynamic characteristic of the electrohydraulic servo valve according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; separating dynamic characteristics of the electro-hydraulic servo valve by adopting a separation method to separate undamped natural frequency of the electro-hydraulic servo valve and damping ratio of the electro-hydraulic servo valve;
the electrohydraulic servo valve fault judging module is used for comparing the control signal of the corresponding remote control unit when the electrohydraulic servo valve zero flow is calculated with the electrohydraulic servo valve zero flow signal threshold value preset in the electrohydraulic servo valve fault judging module, and outputting the electrohydraulic servo valve zero drift overrun when the electrohydraulic servo valve zero flow signal threshold value is exceeded; comparing the undamped natural frequency of the separated electrohydraulic servo valve with an undamped natural frequency threshold of the electrohydraulic servo valve preset in the electrohydraulic servo valve fault judging module, and outputting the clamping stagnation of the electrohydraulic servo valve when the undamped natural frequency threshold of the electrohydraulic servo valve is exceeded; comparing the damping ratio of the separated electrohydraulic servo valve with an electrohydraulic servo valve damping ratio threshold value preset in an electrohydraulic servo valve fault judging module, and outputting electrohydraulic servo valve clamping stagnation when the damping ratio threshold value exceeds the electrohydraulic servo valve damping ratio threshold value;
And the actuator fault judging module is used for outputting actuator clamping stagnation when the actuating loop fault is output by the actuating loop fault judging module, and the electro-hydraulic servo valve fault judging module does not output the zero drift overrun of the electro-hydraulic servo valve and does not output the electro-hydraulic servo valve clamping stagnation.
The fault diagnosis system of the actuation circuit of the civil aircraft flight control system is built in a remote control unit of the actuation circuit.
The fault diagnosis system of the actuation circuit of the civil aircraft flight control system is built in a remote control unit of the actuation circuit. By adopting the form of being built in a remote control unit of the actuating circuit, the fault prediction and the fault positioning of the actuating circuit can be realized under the condition that the structure of the actuating circuit of the existing flight control system is not changed by utilizing a position sensor and a pressure sensor of the actuating circuit.
Embodiment 1, as shown in fig. 1, 3 and 4, is a fault diagnosis method for an actuation circuit of a civil aircraft flight control system, comprising the following steps in sequence:
step one, periodically and continuously collecting position signals of the actuators through the position sensor, correspondingly periodically and continuously collecting pressure signals of the actuators through the pressure sensor, and obtaining control signals of corresponding remote control units.
Step two, identifying dynamic characteristics of an actuating loop according to position signals of a plurality of sampling period actuators and control signals of corresponding remote control units; and separating dynamic characteristics of the actuating circuit by adopting a separation method to separate the undamped natural frequency of the actuating circuit and the damping ratio of the actuating circuit.
According to the position signals of the actuators in a plurality of sampling periods and the control signals of the corresponding remote control units, the dynamic characteristics of the actuating loop are identified as follows:
wherein ,
is the natural frequency of the damping-free of the actuation circuit, < ->
For the damping ratio of the actuation circuit, +.>
Lawster's transformation of the position signal for the actuator, < >>
Law's transformation of control signals for a remote control unit,/->
Is a Laplacian operator;
the separation method adopts inverse transformation from Z domain to S domain to separate out undamped natural frequency of the actuating loop
Damping ratio of the actuating circuit +.>
. Isolation of the undamped natural frequency of the actuating loop using inverse Z-domain to S-domain transformation>
Damping ratio of the actuating circuit +.>
The specific process of (2) is as follows:
first, the dynamic characteristics of the actuation circuit are solved
A corresponding discrete equation root Z;
and converting the discrete equation root Z into a continuous domain root S, wherein the conversion formula is as follows:
Wherein T is the sampling interval between sampling periods;
finally, the undamped natural frequency of the actuating loop can be obtained through the continuous domain root S
Damping ratio of the actuating circuit +.>
。
Dynamic characteristics of the actuation circuit
The corresponding discrete equation is:
wherein ,
sampling period sequence number; />
Is the coefficient to be identified; />
The number of poles; />
The number of the zero points; />
Delay beats; />
Position signal representing actuator->
Is->
Position signal of actuator corresponding to each sampling period, < +.>
Is->
Position signals of actuators corresponding to the sampling periods, and the like;
control signal representing the corresponding remote control unit, < >>
Is->
Control signals of remote control units corresponding to the sampling periods, and so on,/and so on>
Is->
And a control signal of the remote control unit corresponding to the sampling period.
And thirdly, comparing the undamped natural frequency of the separated actuating circuit and the damping ratio of the separated actuating circuit with the undamped natural frequency of the actuating circuit calibrated by a factory and the damping ratio of the actuating circuit calibrated by the factory respectively to obtain the health condition of the actuating circuit. And when the value change between the undamped natural frequency of the separated actuating circuit and the undamped natural frequency of the actuating circuit calibrated by the factory exceeds 40 percent or when the value change between the damping ratio of the separated actuating circuit and the damping ratio of the actuating circuit calibrated by the factory exceeds 40 percent, the actuating circuit fault is obtained.
And step four, calculating the speed of the actuator and the output flow of the electrohydraulic servo valve by adopting an optimal estimation method according to the position signal of the actuator and the pressure signal of the actuator.
The optimal estimation method adopted in the fourth step is a Kalman filtering method of a correction coefficient, and the speed of an actuator and the output flow of an electrohydraulic servo valve are calculated, wherein the specific process is as follows:
first, the flow formula of the electrohydraulic servo valve is as follows:
the forward output flow of the electrohydraulic servo valve is as follows:
wherein ,
for the positive output flow of electrohydraulic servo valve, < >>
Is the flow coefficient; />
Is the density of the liquid; />
For the supply pressure>
For positive output pressure of electrohydraulic servo valve, < >>
For the area of the rod cavity of the actuator, +.>
Is the speed of the actuator;
the negative output flow of the electrohydraulic servo valve is as follows:
wherein ,
for the negative output flow of electrohydraulic servo valve, +.>
Is the flow coefficient; />
Is the density of the liquid; />
For the supply pressure>
For negative output pressure of electrohydraulic servo valve, +.>
Is the rodless cavity area of the actuator, +.>
Is the speed of the actuator;
secondly, linearizing the flow formula of the electrohydraulic servo valve by using a Taylor formula to obtain:
forward output flow of electrohydraulic servo valve:
negative output flow of electrohydraulic servo valve: 
wherein ,
for forward flow gain, +.>
In the form of increments of the control signal of the remote control unit, < >>
Is a positive pressure gain->
The positive output pressure of the electrohydraulic servo valve is increased; />
For negative flow gain, +.>
For negative pressure gain, +.>
An increment form of negative output pressure of the electrohydraulic servo valve;
again, from the actuator pressure model:
wherein ,
is the volume elastic modulus of oil liquid, +.>
Is the rodless cavity volume of the actuator, +.>
For the rod chamber volume of the actuator, +.>
For the position signal of the actuator,>
for the leakage coefficient of the rodless cavity of the actuator, +.>
The rod cavity leakage coefficient is set for the actuator,
for the sampling period +.>
Is->
First derivative with respect to time; the method comprises the steps of carrying out a first treatment on the surface of the />
The motion model of the actuator is established as follows:
wherein ,
representing the mass of the moving part in the actuator, +.>
Representing the motion damping coefficient of a moving part in the actuator,
representing the elastic coefficient of a moving part in the actuator;
the state space model of the actuation circuit is built as follows:
wherein ,
is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time;
finally, after a prediction process noise covariance matrix and a measurement process covariance matrix in Kalman filtering are set, a complete Kalman filtering model is obtained, kalman filtering is realized, and therefore the speed of the actuator and the output flow of the electrohydraulic servo valve are calculated.
Fitting a curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; according to the curve equation, a dichotomy is adopted to calculate the control signal of the corresponding remote control unit when the electrohydraulic servo valve has zero flow.
In the step, according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit, the flow gain of the electrohydraulic servo valve is fitted, and a curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit adopts a least square method, wherein the concrete curve equation is as follows:
wherein ,
for the output flow of electrohydraulic servo valve, +.>
For remote distanceControl signal of control unit, ">
For the flow gain of electrohydraulic servo valve, +.>
Is constant.
And step six, comparing the calculated control signal of the corresponding remote control unit in the zero flow of the electrohydraulic servo valve with a factory calibrated electrohydraulic servo valve zero flow signal to obtain the health condition of the electrohydraulic servo valve. When the calculated value change between the control signal of the corresponding remote control unit and the factory calibrated zero flow signal of the electrohydraulic servo valve exceeds 10%, the zero drift overrun of the electrohydraulic servo valve is obtained.
In the embodiment, the dynamic characteristic of the actuation circuit is established by using the relation between the position sensor and the control signal, and the health condition of the actuation circuit is judged. If the actuating circuit has a problem, the positioning can be continued to judge whether the electrohydraulic servo valve has a fault. Of course, if the actuating loop judges that the actuating loop is free of problems, the actuating loop can also continuously judge whether the electro-hydraulic servo valve has hidden trouble, for example, if the actuating loop possibly has zero drift overrun (even if the actuating loop does not judge the fault at the moment, if the zero drift overrun occurs), relevant personnel can be timely reminded to prepare for overhauling the electro-hydraulic servo valve, and even spare parts are timely prepared for replacement. The invention can find potential hidden trouble and greatly increase the safety of airplane shipping.
Embodiment 2, as shown in fig. 1, 3 and 5, is a fault diagnosis method for an actuation circuit of a civil aircraft flight control system, comprising the following steps in sequence:
step one, periodically and continuously collecting position signals of an actuator through a position sensor, correspondingly periodically and continuously collecting pressure signals of the actuator through a pressure sensor, and obtaining control signals of a corresponding remote control unit;
step two, identifying dynamic characteristics of an actuating loop according to position signals of a plurality of sampling period actuators and control signals of corresponding remote control units; and separating dynamic characteristics of the actuating circuit by adopting a separation method to separate the undamped natural frequency of the actuating circuit and the damping ratio of the actuating circuit.
In this step, according to the position signals of the actuators in a plurality of sampling periods and the control signals of the corresponding remote control units, the dynamic characteristics of the actuation circuit are identified as follows:
wherein ,
is the natural frequency of the damping-free of the actuation circuit, < ->
For the damping ratio of the actuation circuit, +.>
Lawster's transformation of the position signal for the actuator, < >>
Law's transformation of control signals for a remote control unit,/->
Is a Laplacian operator;
The separation method adopts inverse transformation from Z domain to S domain to separate out undamped natural frequency of the actuating loop
Damping ratio of the actuating circuit +.>
. Isolation of the undamped natural frequency of the actuating loop using inverse Z-domain to S-domain transformation>
Damping ratio of the actuating circuit +.>
The specific process of (2) is as follows:
first, the dynamic characteristics of the actuation circuit are solved
A corresponding discrete equation root Z;
and converting the discrete equation root Z into a continuous domain root S, wherein the conversion formula is as follows:
wherein T is the sampling interval between sampling periods;
finally, the undamped natural frequency of the actuating loop can be obtained through the continuous domain root S
Damping ratio of the actuating circuit +.>
。
Dynamic characteristics of the actuation circuit
The corresponding discrete equation is:
wherein ,
sampling period sequence number; />
Is the coefficient to be identified; />
The number of poles; />
The number of the zero points; />
Delay beats; />
Position signal representing actuator->
Is->
Position signal of actuator corresponding to each sampling period, < +.>
Is->
Position signals of actuators corresponding to the sampling periods, and the like;
control signal representing the corresponding remote control unit, < >>
Is->
Control signals of remote control units corresponding to the sampling periods, and so on,/and so on >
Is->
And a control signal of the remote control unit corresponding to the sampling period.
And thirdly, comparing the undamped natural frequency of the separated actuating circuit and the damping ratio of the separated actuating circuit with the undamped natural frequency of the actuating circuit calibrated by a factory and the damping ratio of the actuating circuit calibrated by the factory respectively to obtain the health condition of the actuating circuit. And when the value change between the undamped natural frequency of the separated actuating circuit and the undamped natural frequency of the actuating circuit calibrated by the factory exceeds 40 percent or when the value change between the damping ratio of the separated actuating circuit and the damping ratio of the actuating circuit calibrated by the factory exceeds 40 percent, the actuating circuit fault is obtained.
And step four, calculating the speed of the actuator and the output flow of the electrohydraulic servo valve by adopting an optimal estimation method according to the position signal of the actuator and the pressure signal of the actuator.
The optimal estimation method adopted in the fourth step is a Kalman filtering method of a correction coefficient, and the speed of an actuator and the output flow of an electrohydraulic servo valve are calculated, wherein the specific process is as follows:
first, the flow formula of the electrohydraulic servo valve is as follows:
the forward output flow of the electrohydraulic servo valve is as follows:
wherein ,
for the positive output flow of electrohydraulic servo valve, < > >
Is the flow coefficient; />
Is the density of the liquid; />
For the supply pressure>
For positive output pressure of electrohydraulic servo valve, < >>
For the area of the rod cavity of the actuator, +.>
Is the speed of the actuator;
the negative output flow of the electrohydraulic servo valve is as follows:
wherein ,
for the negative output flow of electrohydraulic servo valve, +.>
Is the flow coefficient; />
Is the density of the liquid; />
For the supply pressure>
For negative output pressure of electrohydraulic servo valve, +.>
Is the rodless cavity area of the actuator, +.>
Is the speed of the actuator;
secondly, linearizing the flow formula of the electrohydraulic servo valve by using a Taylor formula to obtain:
forward output flow of electrohydraulic servo valve:
negative output flow of electrohydraulic servo valve:
wherein ,
for forward flow gain, +.>
In the form of increments of the control signal of the remote control unit, < >>
Is a positive pressure gain->
The positive output pressure of the electrohydraulic servo valve is increased; />
For negative flow gain, +.>
For negative pressure gain, +.>
An increment form of negative output pressure of the electrohydraulic servo valve;
again, from the actuator pressure model:
wherein ,
is the volume elastic modulus of oil liquid, +.>
Is the rodless cavity volume of the actuator, +.>
For the rod chamber volume of the actuator, +. >
For the position signal of the actuator,>
for the leakage coefficient of the rodless cavity of the actuator, +.>
The rod cavity leakage coefficient is set for the actuator,
for the sampling period +.>
Is->
First derivative with respect to time;
the motion model of the actuator is established as follows:
wherein ,
representing the mass of the moving part in the actuator, +.>
Representing the motion damping coefficient of a moving part in the actuator,
representing the elastic coefficient of a moving part in the actuator;
the state space model of the actuation circuit is built as follows:
wherein ,
is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time;
finally, after a prediction process noise covariance matrix and a measurement process covariance matrix in Kalman filtering are set, a complete Kalman filtering model is obtained, kalman filtering is realized, and therefore the speed of the actuator and the output flow of the electrohydraulic servo valve are calculated.
Fitting a curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; according to the curve equation, a dichotomy is adopted to calculate the control signal of the corresponding remote control unit when the electrohydraulic servo valve has zero flow.
In the step, according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit, the flow gain of the electrohydraulic servo valve is fitted, and a curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit adopts a least square method, wherein the concrete curve equation is as follows:
wherein ,
for the output flow of electrohydraulic servo valve, +.>
For the control signal of the remote control unit, +.>
For the flow gain of electrohydraulic servo valve, +.>
Is constant.
Step six, identifying the dynamic characteristics of the electrohydraulic servo valve according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; and separating the dynamic characteristics of the electrohydraulic servo valve by adopting a separation method to separate the undamped natural frequency of the electrohydraulic servo valve and the damping ratio of the electrohydraulic servo valve.
In the step, according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit, the dynamic characteristics of the electrohydraulic servo valve are identified as follows:
wherein ,
is the undamped natural frequency of the electrohydraulic servo valve, < ->
Is the damping ratio of electrohydraulic servo valve, +. >
Law's transformation of the output flow of the electrohydraulic servo valve,>
law's transformation of control signals for a remote control unit,/->
Is a Laplacian operator;
the separation method adopts inverse transformation from Z domain to S domain to separate out undamped natural frequency of electrohydraulic servo valve
Damping ratio with electrohydraulic servo valve>
。
The undamped natural frequency of the electrohydraulic servo valve is separated by adopting the inverse transformation from the Z domain to the S domain
Damping ratio with electrohydraulic servo valve>
The specific process of (2) is as follows:
first, solving the dynamic characteristics of electrohydraulic servo valve
A corresponding discrete equation root Z;
and converting the discrete equation root Z into a continuous domain root S, wherein the conversion formula is as follows:
wherein T is the sampling interval between sampling periods;
finally, the undamped natural frequency of the electrohydraulic servo valve can be obtained through the continuous domain root S
Damping ratio with electrohydraulic servo valve>
。
Wherein, dynamic characteristics of electrohydraulic servo valve
The corresponding discrete equation is:
wherein ,
sampling period sequence number; />
Is the coefficient to be identified; />
The number of poles; />
The number of the zero points; />
Delay beats; />
Position signal representing actuator->
Is->
Position signal of actuator corresponding to each sampling period, < +.>
Is->
Position signals of actuators corresponding to the sampling periods, and the like; 
Control signal representing the corresponding remote control unit, < >>
Is->
Control signals of remote control units corresponding to the sampling periods, and so on,/and so on>
Is->
And a control signal of the remote control unit corresponding to the sampling period.
And seventhly, comparing the calculated control signal of the corresponding remote control unit when the electrohydraulic servo valve is at zero flow, the undamped natural frequency of the separated electrohydraulic servo valve and the damping ratio of the separated electrohydraulic servo valve with the zero flow signal of the factory calibrated electrohydraulic servo valve, the undamped natural frequency of the factory calibrated electrohydraulic servo valve and the damping ratio of the factory calibrated electrohydraulic servo valve respectively to obtain the health condition of the electrohydraulic servo valve. When the calculated value change between the control signal of the corresponding remote control unit and the factory calibrated zero flow signal of the electrohydraulic servo valve exceeds 10%, obtaining zero drift overrun of the electrohydraulic servo valve; when the value change between the undamped natural frequency of the separated electrohydraulic servo valve and the undamped natural frequency of the electrohydraulic servo valve calibrated by a factory exceeds 40%, the clamping stagnation of the electrohydraulic servo valve is obtained; and when the value change between the damping ratio of the separated electrohydraulic servo valve and the damping ratio of the electrohydraulic servo valve calibrated by a factory exceeds 40%, the clamping stagnation of the electrohydraulic servo valve is obtained.
Step eight: and when the action loop fault is obtained in the third step, and the electro-hydraulic servo zero drift overrun is not obtained in the seventh step, the electro-hydraulic servo valve clamping stagnation is not obtained, and the actuator clamping stagnation is obtained.
According to the embodiment, various fault hidden dangers of the actuating loop can be found in time, and the fault hidden dangers can be classified and reminded, so that the working efficiency of overhaulers is improved.
Embodiment 3, as shown in fig. 1, 3 and 6, is a fault diagnosis method for an actuation circuit of a civil aircraft flight control system, comprising the following steps in sequence:
step one, periodically and continuously collecting position signals of an actuator through a position sensor, correspondingly periodically and continuously collecting pressure signals of the actuator through a pressure sensor, and obtaining control signals of a corresponding remote control unit;
and secondly, calculating the speed of the actuator and the output flow of the electrohydraulic servo valve by adopting an optimal estimation method according to the position signal of the actuator and the pressure signal of the actuator.
The best estimation method adopted by the embodiment is a Kalman filtering method of a correction coefficient, and the speed of an actuator and the output flow of an electrohydraulic servo valve are calculated by the following specific processes:
first, the flow formula of the electrohydraulic servo valve is as follows:
The forward output flow of the electrohydraulic servo valve is as follows:
wherein ,
for the positive output flow of electrohydraulic servo valve, < >>
Is the flow coefficient; />
Is the density of the liquid; />
For the supply pressure>
For positive output pressure of electrohydraulic servo valve, < >>
For the area of the rod cavity of the actuator, +.>
Is the speed of the actuator;
the negative output flow of the electrohydraulic servo valve is as follows:
wherein ,
for the negative output flow of electrohydraulic servo valve, +.>
Is the flow coefficient; />
Is the density of the liquid; />
For the supply pressure>
For negative output pressure of electrohydraulic servo valve, +.>
Is the rodless cavity area of the actuator, +.>
Is the speed of the actuator;
secondly, linearizing the flow formula of the electrohydraulic servo valve by using a Taylor formula to obtain:
forward output flow of electrohydraulic servo valve:
negative output flow of electrohydraulic servo valve:
wherein ,
for forward flow gain, +.>
In the form of increments of the control signal of the remote control unit, < >>
Is a positive pressure gain->
The positive output pressure of the electrohydraulic servo valve is increased; />
For negative flow gain, +.>
For negative pressure gain, +.>
An increment form of negative output pressure of the electrohydraulic servo valve;
again, from the actuator pressure model:
wherein ,
Is the volume elastic modulus of oil liquid, +.>
Is the rodless cavity volume of the actuator, +.>
For the rod chamber volume of the actuator, +.>
For the position signal of the actuator,>
for the leakage coefficient of the rodless cavity of the actuator, +.>
The rod cavity leakage coefficient is set for the actuator,
for the sampling period +.>
Is->
First derivative with respect to time;
the motion model of the actuator is established as follows:
wherein ,
representing the mass of the moving part in the actuator, +.>
Representing the motion damping coefficient of a moving part in the actuator,
elastic system representing moving element in actuatorA number;
the state space model of the actuation circuit is built as follows:
wherein ,
is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time;
Finally, after a prediction process noise covariance matrix and a measurement process covariance matrix in Kalman filtering are set, a complete Kalman filtering model is obtained, kalman filtering is realized, and therefore the speed of the actuator and the output flow of the electrohydraulic servo valve are calculated.
Fitting a curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; according to the curve equation, a dichotomy is adopted to calculate the control signal of the corresponding remote control unit when the electrohydraulic servo valve has zero flow.
The output flow of the electrohydraulic servo valve calculated according to the plurality of sampling periods and the control signal of the corresponding remote control unit are fitted to obtain the flow gain of the electrohydraulic servo valve, and a curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit adopts a least square method, and the specific curve equation is as follows:
wherein ,
for the output flow of electrohydraulic servo valve, +.>
For the control signal of the remote control unit, +.>
For the flow gain of electrohydraulic servo valve, +.>
Is constant.
Step four, identifying the dynamic characteristics of the electrohydraulic servo valve according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; and separating the dynamic characteristics of the electrohydraulic servo valve by adopting a separation method to separate the undamped natural frequency of the electrohydraulic servo valve and the damping ratio of the electrohydraulic servo valve.
The method comprises the following steps of identifying the dynamic characteristics of the electrohydraulic servo valve according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of a corresponding remote control unit:
wherein ,
is the undamped natural frequency of the electrohydraulic servo valve, < ->
Is the damping ratio of electrohydraulic servo valve, +.>
Law's transformation of the output flow of the electrohydraulic servo valve,>
law's transformation of control signals for a remote control unit,/->
Is a Laplacian operator;
the separation method adopts inverse transformation from Z domain to S domain to separate out undamped natural frequency of electrohydraulic servo valve
Damping ratio with electrohydraulic servo valve>
。
The undamped natural frequency of the electrohydraulic servo valve is separated by adopting the inverse transformation from the Z domain to the S domain
Damping ratio with electrohydraulic servo valve>
The specific process of (2) is as follows:
first, solving the dynamic characteristics of electrohydraulic servo valve
A corresponding discrete equation root Z;
and converting the discrete equation root Z into a continuous domain root S, wherein the conversion formula is as follows:
wherein T is the sampling interval between sampling periods;
finally, the undamped natural frequency of the electrohydraulic servo valve can be obtained through the continuous domain root S
Damping ratio with electrohydraulic servo valve>
。
Wherein, dynamic characteristics of electrohydraulic servo valve
The corresponding discrete equation is:
wherein ,
sampling period sequence number; />
Is the coefficient to be identified; />
The number of poles; />
The number of the zero points; />
Delay beats; />
Position signal representing actuator->
Is->
Position signal of actuator corresponding to each sampling period, < +.>
Is->
Position signals of actuators corresponding to the sampling periods, and the like;
control signal representing the corresponding remote control unit, < >>
Is->
Control signals of remote control units corresponding to the sampling periods, and so on,/and so on>
Is->
And a control signal of the remote control unit corresponding to the sampling period.
And fifthly, comparing the calculated control signals of the corresponding remote control units, the undamped natural frequency of the separated electrohydraulic servo valve and the damping ratio of the separated electrohydraulic servo valve with the zero flow signals of the factory calibrated electrohydraulic servo valve, the undamped natural frequency of the factory calibrated electrohydraulic servo valve and the damping ratio of the factory calibrated electrohydraulic servo valve to obtain the health condition of the electrohydraulic servo valve. When the calculated value change between the control signal of the corresponding remote control unit and the factory calibrated zero flow signal of the electrohydraulic servo valve exceeds 10%, obtaining zero drift overrun of the electrohydraulic servo valve; when the value change between the undamped natural frequency of the separated electrohydraulic servo valve and the undamped natural frequency of the electrohydraulic servo valve calibrated by a factory exceeds 40%, the clamping stagnation of the electrohydraulic servo valve is obtained; and when the value change between the damping ratio of the separated electrohydraulic servo valve and the damping ratio of the electrohydraulic servo valve calibrated by a factory exceeds 40%, the clamping stagnation of the electrohydraulic servo valve is obtained.
Step six, identifying dynamic characteristics of the actuating loop according to position signals of a plurality of sampling period actuators and control signals of corresponding remote control units; and separating dynamic characteristics of the actuating circuit by adopting a separation method to separate the undamped natural frequency of the actuating circuit and the damping ratio of the actuating circuit.
In this step, according to the position signals of the actuators in a plurality of sampling periods and the control signals of the corresponding remote control units, the dynamic characteristics of the actuation circuit are identified as follows:
wherein ,
is the natural frequency of the damping-free of the actuation circuit, < ->
For the damping ratio of the actuation circuit, +.>
Lawster's transformation of the position signal for the actuator, < >>
Law's transformation of control signals for a remote control unit,/->
Is a Laplacian operator;
the separation method adopts inverse transformation from Z domain to S domain to separate out undamped natural frequency of the actuating loop
Damping ratio of the actuating circuit +.>
。/>
In the present embodiment, the undamped natural frequency of the actuating loop is separated by inverse transformation from Z domain to S domain
Damping ratio of the actuating circuit +.>
The specific process of (2) is as follows:
first, the dynamic characteristics of the actuation circuit are solved
A corresponding discrete equation root Z;
and converting the discrete equation root Z into a continuous domain root S, wherein the conversion formula is as follows:
Wherein T is the sampling interval between sampling periods;
finally, the undamped natural frequency of the actuating loop can be obtained through the continuous domain root S
Damping ratio of the actuating circuit +.>
。
Dynamic characteristics of the actuation circuit
The corresponding discrete equation is:
wherein ,
sampling period sequence number; />
Is the coefficient to be identified; />
The number of poles; />
The number of the zero points; />
Delay beats; />
Position signal representing actuator->
Is->
Position signal of actuator corresponding to each sampling period, < +.>
Is->
Position signals of actuators corresponding to the sampling periods, and the like;
control signal representing the corresponding remote control unit, < >>
Is->
Control signals of remote control units corresponding to the sampling periods, and so on,/and so on>
Is->
And a control signal of the remote control unit corresponding to the sampling period.
And step seven, comparing the undamped natural frequency of the separated actuating circuit and the damping ratio of the separated actuating circuit with the undamped natural frequency of the actuating circuit calibrated by a factory and the damping ratio of the actuating circuit calibrated by the factory respectively to obtain the health condition of the actuating circuit. And when the value change between the undamped natural frequency of the separated actuating circuit and the undamped natural frequency of the actuating circuit calibrated by the factory exceeds 40 percent or when the value change between the damping ratio of the separated actuating circuit and the damping ratio of the actuating circuit calibrated by the factory exceeds 40 percent, the actuating circuit fault is obtained.
And step eight, when the electro-hydraulic servo zero drift overrun is not obtained in the step five, the electro-hydraulic servo valve clamping stagnation is not obtained, and the actuating loop fault is obtained in the step seven, the actuator clamping stagnation is obtained.
In the fault diagnosis process, the scheme of the embodiment gives priority to the fault health condition of the electro-hydraulic servo valve of the vulnerable part, and then judges the fault health condition of the whole action loop, so that the specific cause of the fault of the action loop is positioned, fault isolation and quick positioning analysis can be realized, and the method is also beneficial to finding some hidden trouble faults of the electro-hydraulic servo valve in advance. The diagnosis method of the embodiment can provide reference for aviation stock in advance, and save maintenance and replacement time. The fault positioning can provide reference for repair of the LRU returned to the factory, and the repair efficiency can be improved. Meanwhile, the system has a fault prediction and early warning function, so that a hidden early fault can be found before the system, and related parts can be reminded to be replaced in advance, thereby enhancing the operation safety of the civil aircraft.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (39)
1. A civil aircraft flight control system actuation circuit fault diagnosis system, characterized in that it comprises:
the signal acquisition module is used for periodically and continuously acquiring a position signal of the actuator, a pressure signal of the actuator and a control signal of a corresponding remote control unit;
the actuating circuit dynamic characteristic identification module is used for identifying the dynamic characteristic of the actuating circuit according to the position signals of the actuators in a plurality of sampling periods and the control signals of the corresponding remote control units; separating dynamic characteristics of the actuating circuit by adopting a separation method to separate undamped natural frequency of the actuating circuit and damping ratio of the actuating circuit;
and the actuating loop fault judging module is used for comparing the undamped natural frequency of the separated actuating loop with an actuating loop undamped natural frequency threshold preset in the actuating loop fault judging module, and outputting the actuating loop fault when the undamped natural frequency of the actuating loop exceeds the actuating loop undamped natural frequency threshold.
2. The civil aircraft flight control system actuation circuit fault diagnosis system of claim 1, further comprising:
the output flow calculating module is used for calculating the speed of the actuator and the output flow of the electrohydraulic servo valve by adopting an optimal estimation method according to the position signal of the actuator and the pressure signal of the actuator;
The curve equation fitting module is used for fitting out the flow gain of the electrohydraulic servo valve and the curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; according to the curve equation, calculating a control signal of a corresponding remote control unit when the electrohydraulic servo valve has zero flow by adopting a dichotomy;
and the electrohydraulic servo valve fault judging module is used for comparing the control signal of the corresponding remote control unit when the electrohydraulic servo valve zero flow is calculated with the electrohydraulic servo valve zero flow signal threshold value preset in the electrohydraulic servo valve fault judging module, and outputting the electrohydraulic servo valve zero drift overrun when the electrohydraulic servo valve zero flow signal threshold value is exceeded.
3. The civil aircraft flight control system actuation circuit fault diagnosis system of claim 1, further comprising:
the output flow calculating module is used for calculating the speed of the actuator and the output flow of the electrohydraulic servo valve by adopting an optimal estimation method according to the position signal of the actuator and the pressure signal of the actuator;
The curve equation fitting module is used for fitting out the flow gain of the electrohydraulic servo valve and the curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; according to the curve equation, calculating a control signal of a corresponding remote control unit when the electrohydraulic servo valve has zero flow by adopting a dichotomy;
the electrohydraulic servo valve dynamic characteristic identification module is used for identifying the dynamic characteristic of the electrohydraulic servo valve according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; separating dynamic characteristics of the electro-hydraulic servo valve by adopting a separation method to separate undamped natural frequency of the electro-hydraulic servo valve and damping ratio of the electro-hydraulic servo valve;
the electrohydraulic servo valve fault judging module is used for comparing the control signal of the corresponding remote control unit when the electrohydraulic servo valve zero flow is calculated with the electrohydraulic servo valve zero flow signal threshold value preset in the electrohydraulic servo valve fault judging module, and outputting the electrohydraulic servo valve zero drift overrun when the electrohydraulic servo valve zero flow signal threshold value is exceeded; comparing the undamped natural frequency of the separated electrohydraulic servo valve with an undamped natural frequency threshold of the electrohydraulic servo valve preset in the electrohydraulic servo valve fault judging module, and outputting the clamping stagnation of the electrohydraulic servo valve when the undamped natural frequency threshold of the electrohydraulic servo valve is exceeded.
4. The civil aircraft flight control system actuation circuit fault diagnosis system of claim 1, further comprising:
the output flow calculating module is used for calculating the speed of the actuator and the output flow of the electrohydraulic servo valve by adopting an optimal estimation method according to the position signal of the actuator and the pressure signal of the actuator;
the curve equation fitting module is used for fitting out the flow gain of the electrohydraulic servo valve and the curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; according to the curve equation, calculating a control signal of a corresponding remote control unit when the electrohydraulic servo valve has zero flow by adopting a dichotomy;
the electrohydraulic servo valve dynamic characteristic identification module is used for identifying the dynamic characteristic of the electrohydraulic servo valve according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; separating dynamic characteristics of the electro-hydraulic servo valve by adopting a separation method to separate undamped natural frequency of the electro-hydraulic servo valve and damping ratio of the electro-hydraulic servo valve;
The electrohydraulic servo valve fault judging module is used for comparing the control signal of the corresponding remote control unit when the electrohydraulic servo valve zero flow is calculated with the electrohydraulic servo valve zero flow signal threshold value preset in the electrohydraulic servo valve fault judging module, and outputting the electrohydraulic servo valve zero drift overrun when the electrohydraulic servo valve zero flow signal threshold value is exceeded; comparing the undamped natural frequency of the separated electrohydraulic servo valve with an undamped natural frequency threshold of the electrohydraulic servo valve preset in the electrohydraulic servo valve fault judging module, and outputting the clamping stagnation of the electrohydraulic servo valve when the undamped natural frequency threshold of the electrohydraulic servo valve is exceeded; and comparing the damping ratio of the separated electrohydraulic servo valve with an electrohydraulic servo valve damping ratio threshold value preset in an electrohydraulic servo valve fault judging module, and outputting electrohydraulic servo valve clamping stagnation when the damping ratio threshold value of the electrohydraulic servo valve is exceeded.
5. The civil aircraft flight control system actuation circuit fault diagnosis system of claim 4, further comprising:
and the actuator fault judging module is used for outputting actuator clamping stagnation when the actuating loop fault is output by the actuating loop fault judging module, and the electro-hydraulic servo valve fault judging module does not output the zero drift overrun of the electro-hydraulic servo valve and does not output the electro-hydraulic servo valve clamping stagnation.
6. A civil aircraft flight control system actuation circuit fault diagnosis system as claimed in any one of claims 1 to 5, which is built into the actuation circuit remote control unit.
7. A civil aircraft flight control system actuation loop fault diagnosis method is characterized by comprising the following steps in sequence:
step one, periodically and continuously collecting position signals of an actuator through a position sensor, correspondingly periodically and continuously collecting pressure signals of the actuator through a pressure sensor, and obtaining control signals of a corresponding remote control unit;
step two, identifying dynamic characteristics of an actuating loop according to position signals of a plurality of sampling period actuators and control signals of corresponding remote control units; separating dynamic characteristics of the actuating circuit by adopting a separation method to separate undamped natural frequency of the actuating circuit and damping ratio of the actuating circuit;
and thirdly, comparing the undamped natural frequency of the separated actuating circuit and the damping ratio of the separated actuating circuit with the undamped natural frequency of the actuating circuit calibrated by a factory and the damping ratio of the actuating circuit calibrated by the factory respectively to obtain the health condition of the actuating circuit.
8. The method for diagnosing faults in an actuation circuit of a civil aircraft flight control system as claimed in claim 7, wherein in the third step, the specific process for obtaining the health condition of the actuation circuit is as follows:
and when the value change between the undamped natural frequency of the separated actuating circuit and the undamped natural frequency of the actuating circuit calibrated by the factory exceeds 40 percent or when the value change between the damping ratio of the separated actuating circuit and the damping ratio of the actuating circuit calibrated by the factory exceeds 40 percent, the actuating circuit fault is obtained.
9. The method for diagnosing a fault in an actuation circuit of a civil aircraft flight control system as claimed in claim 8, further comprising, after step three, the following sequential steps:
calculating the speed of the actuator and the output flow of the electrohydraulic servo valve by adopting an optimal estimation method according to the position signal of the actuator and the pressure signal of the actuator;
fitting a curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; according to the curve equation, calculating a control signal of a corresponding remote control unit when the electrohydraulic servo valve has zero flow by adopting a dichotomy;
And step six, comparing the calculated control signal of the corresponding remote control unit in the zero flow of the electrohydraulic servo valve with a factory calibrated electrohydraulic servo valve zero flow signal to obtain the health condition of the electrohydraulic servo valve.
10. The method for diagnosing faults of an actuating circuit of a civil aircraft flight control system according to claim 9, wherein in the sixth step, the specific process of obtaining the health condition of the electro-hydraulic servo valve is as follows:
when the calculated value change between the control signal of the corresponding remote control unit and the factory calibrated zero flow signal of the electrohydraulic servo valve exceeds 10%, the zero drift overrun of the electrohydraulic servo valve is obtained.
11. The method for diagnosing faults in an actuation circuit of a civil aircraft flight control system as claimed in claim 10, wherein in the second step, the dynamic characteristics of the actuation circuit are identified as follows:
wherein ,
is the natural frequency of the damping-free of the actuation circuit, < ->
For the damping ratio of the actuation circuit, +.>
Lawster's transformation of the position signal for the actuator, < >>
Law's transformation of control signals for a remote control unit,/->
Is a Laplacian operator;
the separation method adopts inverse transformation from Z domain to S domain to separate out undamped natural frequency of the actuating loop 
Damping ratio of the actuating circuit +.>
。
12. The method for diagnosing faults in an actuation circuit of a civil aircraft flight control system as claimed in claim 11, wherein in said step two, the non-damped natural frequency of the actuation circuit is separated by inverse transformation from Z domain to S domain
Damping ratio of the actuating circuit +.>
The specific process of (2) is as follows:
firstly, solving a discrete equation root Z corresponding to dynamic characteristics of an actuating loop;
and converting the discrete equation root Z into a continuous domain root S, wherein the conversion formula is as follows:
wherein T is the sampling interval between sampling periods;
finally, the undamped natural frequency of the actuating loop can be obtained through the continuous domain root S
Damping ratio of the actuating circuit
。
13. The method for diagnosing a fault in an actuation circuit of a civil aircraft flight control system according to claim 12, wherein in the second step, a discrete equation corresponding to a dynamic characteristic of the actuation circuit is:
wherein ,
sampling period sequence number; />
Is the coefficient to be identified; />
The number of poles;
the number of the zero points; />
Delay beats; />
Position signal representing actuator->
Is->
Position signal of actuator corresponding to each sampling period, < +.>
Is->
Actuators corresponding to a sampling period Position signal, and so on; />
Control signal representing the corresponding remote control unit, < >>
Is->
Control signals of remote control units corresponding to the sampling periods, and so on,/and so on>
Is->
And a control signal of the remote control unit corresponding to the sampling period.
14. The method for diagnosing faults of an actuating circuit of a civil aircraft flight control system according to claim 13, wherein the best estimation method adopted in the fourth step is a Kalman filtering method of a correction coefficient, and the speed of an actuator and the output flow of an electrohydraulic servo valve are calculated by the following specific processes:
first, the flow formula of the electrohydraulic servo valve is as follows:
the forward output flow of the electrohydraulic servo valve is as follows:
wherein ,
for the positive output flow of electrohydraulic servo valve, < >>
Is the flow coefficient; />
Is the density of the liquid; />
For the supply pressure>
For positive output pressure of electrohydraulic servo valve, < >>
For the area of the rod cavity of the actuator, +.>
Is the speed of the actuator;
the negative output flow of the electrohydraulic servo valve is as follows:
wherein ,
for the negative output flow of electrohydraulic servo valve, +.>
Is the flow coefficient; />
Is the density of the liquid; />
For the supply pressure>
For negative output pressure of electrohydraulic servo valve, +. >
Is the rodless cavity area of the actuator, +.>
Is the speed of the actuator;
secondly, linearizing the flow formula of the electrohydraulic servo valve by using a Taylor formula to obtain:
forward output flow of electrohydraulic servo valve:
negative output flow of electrohydraulic servo valve:
wherein ,
for forward flow gain, +.>
In the form of increments of the control signal of the remote control unit, < >>
Is a positive pressure gain->
The positive output pressure of the electrohydraulic servo valve is increased; />
For negative flow gain, +.>
For negative pressure gain, +.>
An increment form of negative output pressure of the electrohydraulic servo valve;
again, from the actuator pressure model:
wherein ,
is the volume elastic modulus of oil liquid, +.>
Is the rodless cavity volume of the actuator, +.>
For the rod chamber volume of the actuator, +.>
For the position signal of the actuator,>
for the leakage coefficient of the rodless cavity of the actuator, +.>
For actuators with rod chamber leakage coefficient +.>
For the sampling period +.>
Is->
First derivative with respect to time;
the motion model of the actuator is established as follows:
wherein ,
representing the mass of the moving part in the actuator, +.>
Representing the motion damping coefficient of a moving part in the actuator, < + >>
Representing the elastic coefficient of a moving part in the actuator;
the state space model of the actuation circuit is built as follows:
wherein ,
is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time;
Finally, after a prediction process noise covariance matrix and a measurement process covariance matrix in Kalman filtering are set, a complete Kalman filtering model is obtained, kalman filtering is realized, and therefore the speed of the actuator and the output flow of the electrohydraulic servo valve are calculated.
15. The method for diagnosing faults of an actuating circuit of a flight control system of a civil aircraft according to claim 14, wherein in the fifth step, the output flow of the electrohydraulic servo valve calculated according to a plurality of sampling periods and the control signal of the corresponding remote control unit are fitted to obtain the flow gain of the electrohydraulic servo valve, and a curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit is a least square method, and the specific curve equation is as follows:
wherein ,
for the output flow of electrohydraulic servo valve, +.>
For the control signal of the remote control unit, +. >
For the flow gain of electrohydraulic servo valve, +.>
Is constant.
16. The method for diagnosing a fault in an actuation circuit of a civil aircraft flight control system as claimed in claim 8, further comprising, after step three, the following steps in order:
calculating the speed of the actuator and the output flow of the electrohydraulic servo valve by adopting an optimal estimation method according to the position signal of the actuator and the pressure signal of the actuator;
fitting a curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; according to the curve equation, calculating a control signal of a corresponding remote control unit when the electrohydraulic servo valve has zero flow;
step six, identifying the dynamic characteristics of the electrohydraulic servo valve according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; separating dynamic characteristics of the electro-hydraulic servo valve by adopting a separation method to separate undamped natural frequency of the electro-hydraulic servo valve and damping ratio of the electro-hydraulic servo valve;
And seventhly, comparing the calculated control signal of the corresponding remote control unit when the electrohydraulic servo valve is at zero flow, the undamped natural frequency of the separated electrohydraulic servo valve and the damping ratio of the separated electrohydraulic servo valve with the zero flow signal of the factory calibrated electrohydraulic servo valve, the undamped natural frequency of the factory calibrated electrohydraulic servo valve and the damping ratio of the factory calibrated electrohydraulic servo valve respectively to obtain the health condition of the electrohydraulic servo valve.
17. The method for diagnosing faults in an actuation circuit of a flight control system of a civil aircraft according to claim 16, wherein in the seventh step, the specific process for obtaining the health condition of the electrohydraulic servo valve is as follows:
when the calculated value change between the control signal of the corresponding remote control unit and the factory calibrated zero flow signal of the electrohydraulic servo valve exceeds 10%, obtaining zero drift overrun of the electrohydraulic servo valve;
when the value change between the undamped natural frequency of the separated electrohydraulic servo valve and the undamped natural frequency of the electrohydraulic servo valve calibrated by a factory exceeds 40%, the clamping stagnation of the electrohydraulic servo valve is obtained;
and when the value change between the damping ratio of the separated electrohydraulic servo valve and the damping ratio of the electrohydraulic servo valve calibrated by a factory exceeds 40%, the clamping stagnation of the electrohydraulic servo valve is obtained.
18. The method for diagnosing a fault in an actuation circuit of a civil aircraft flight control system as claimed in claim 17, further comprising, after step seven, the steps of:
step eight: and when the action loop fault is obtained in the third step, and the electro-hydraulic servo zero drift overrun is not obtained in the seventh step, the electro-hydraulic servo valve clamping stagnation is not obtained, and the actuator clamping stagnation is obtained.
19. The method for diagnosing a fault in an actuation circuit of a civil aircraft flight control system as claimed in claim 18, wherein in the second step, the dynamic characteristics of the actuation circuit are identified as follows:
wherein ,
is the natural frequency of the damping-free of the actuation circuit, < ->
For the damping ratio of the actuation circuit, +.>
Lawster's transformation of the position signal for the actuator, < >>
Law's transformation of control signals for a remote control unit,/->
Is a Laplacian operator; />
The separation method adopts inverse transformation from Z domain to S domain to separate out undamped natural frequency of the actuating loop
Damping ratio of the actuating circuit +.>
。
20. The method for diagnosing a fault in an actuation circuit of a civil aircraft flight control system as claimed in claim 19, wherein in said step two, the natural frequency of the actuation circuit is separated 
Damping ratio of the actuating circuit +.>
The specific process of (2) is as follows:
firstly, solving a discrete equation root Z corresponding to dynamic characteristics of an actuating loop;
and converting the discrete equation root Z into a continuous domain root S, wherein the conversion formula is as follows:
wherein T is the sampling interval between sampling periods;
finally, the undamped natural frequency of the actuating loop can be obtained through the continuous domain root S
Damping ratio of the actuating circuit
。
21. The method for diagnosing a fault in an actuation circuit of a civil aircraft flight control system according to claim 20, wherein in the second step, a discrete equation corresponding to a dynamic characteristic of the actuation circuit is:
wherein ,
sampling period sequence number; />
Is the coefficient to be identified; />
The number of poles;
the number of the zero points; />
Delay beats; />
Position signal representing actuator->
Is->
Position signal of actuator corresponding to each sampling period, < +.>
Is->
Position signals of actuators corresponding to the sampling periods, and the like; />
Control signal representing the corresponding remote control unit, < >>
Is->
Control signals of remote control units corresponding to the sampling periods, and so on,/and so on>
Is->
And a control signal of the remote control unit corresponding to the sampling period.
22. The method for diagnosing faults in an actuating circuit of a flight control system of a civil aircraft according to claim 21, wherein the best estimation method adopted in the fourth step is a kalman filter method of correction coefficient, and the speed of the actuator and the output flow of the electrohydraulic servo valve are calculated by the following steps:
first, the flow formula of the electrohydraulic servo valve is as follows:
the forward output flow of the electrohydraulic servo valve is as follows:
wherein ,
for positive output flow of electrohydraulic servo valvesQuantity (S)>
Is the flow coefficient; />
Is the density of the liquid; />
For the supply pressure>
For positive output pressure of electrohydraulic servo valve, < >>
For the area of the rod cavity of the actuator, +.>
Is the speed of the actuator;
the negative output flow of the electrohydraulic servo valve is as follows:
wherein ,
for the negative output flow of electrohydraulic servo valve, +.>
Is the flow coefficient; />
Is the density of the liquid; />
For the supply pressure>
For negative output pressure of electrohydraulic servo valve, +.>
Is the rodless cavity area of the actuator, +.>
Is the speed of the actuator;
secondly, linearizing the flow formula of the electrohydraulic servo valve by using a Taylor formula to obtain:
forward output flow of electrohydraulic servo valve:
negative output flow of electrohydraulic servo valve:
wherein ,
For forward flow gain, +.>
In the form of increments of the control signal of the remote control unit, < >>
Is a positive pressure gain->
The positive output pressure of the electrohydraulic servo valve is increased; />
For negative flow gain, +.>
For negative pressure gain, +.>
An increment form of negative output pressure of the electrohydraulic servo valve;
again, from the actuator pressure model:
wherein ,
is the volume elastic modulus of oil liquid, +.>
Is the rodless cavity volume of the actuator, +.>
For the rod chamber volume of the actuator, +.>
For the position signal of the actuator,>
for the leakage coefficient of the rodless cavity of the actuator, +.>
For actuators with rod chamber leakage coefficient +.>
For the sampling period +.>
Is->
First derivative with respect to time;
the motion model of the actuator is established as follows:
wherein ,
representing the mass of the moving part in the actuator, +.>
Representing the motion damping coefficient of a moving part in the actuator, < + >>
Representing the elastic coefficient of a moving part in the actuator;
the state space model of the actuation circuit is built as follows:
wherein ,
is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time; />
Finally, after a prediction process noise covariance matrix and a measurement process covariance matrix in Kalman filtering are set, a complete Kalman filtering model is obtained, kalman filtering is realized, and therefore the speed of the actuator and the output flow of the electrohydraulic servo valve are calculated.
23. The method for diagnosing faults in an actuation circuit of a flight control system of a civil aircraft according to claim 22, wherein in the fifth step, the output flow of the electro-hydraulic servo valve calculated according to a plurality of sampling periods and the control signal of the corresponding remote control unit are fitted to obtain the flow gain of the electro-hydraulic servo valve, and a curve equation between the output flow of the electro-hydraulic servo valve and the control signal of the remote control unit is a least square method, and the specific curve equation is as follows:
wherein ,
for the output flow of electrohydraulic servo valve, +.>
For remote control unitsControl signal->
For the flow gain of electrohydraulic servo valve, +.>
Is constant.
24. The method for diagnosing faults in an actuation circuit of a flight control system of a civil aircraft as claimed in claim 23, wherein in the sixth step, the dynamic characteristics of the electro-hydraulic servo valve are identified as follows:
wherein ,
is the undamped natural frequency of the electrohydraulic servo valve, < ->
Is the damping ratio of electrohydraulic servo valve, +.>
Law's transformation of the output flow of the electrohydraulic servo valve,>
law's transformation of control signals for a remote control unit,/->
Is a Laplacian operator;
the separation method adopts inverse transformation from Z domain to S domain to separate out undamped natural frequency of electrohydraulic servo valve
Damping ratio with electrohydraulic servo valve>
。
25. The method for diagnosing faults in an actuation circuit of a flight control system of a civil aircraft as claimed in claim 24, wherein in said step six, the undamped natural frequency of the electrohydraulic servo valve is isolated
Damping ratio with electrohydraulic servo valve>
The specific process of (2) is as follows:
firstly, solving a discrete equation root Z corresponding to the dynamic characteristics of an electrohydraulic servo valve;
and converting the discrete equation root Z into a continuous domain root S, wherein the conversion formula is as follows:
wherein T is the sampling interval between sampling periods;
finally, the undamped natural frequency of the electrohydraulic servo valve can be obtained through the continuous domain root S
Damping ratio with electrohydraulic servo valve>
。
26. The method for diagnosing a fault in an actuation circuit of a civil aircraft flight control system according to claim 25, wherein in the sixth step, a discrete equation corresponding to a dynamic characteristic of the electrohydraulic servo valve is:
wherein ,
sampling period sequence number; />
Is the coefficient to be identified; />
The number of poles;
the number of the zero points; />
Delay beats; />
Position signal representing actuator->
Is->
Position signal of actuator corresponding to each sampling period, < +.>
Is->
Position signals of actuators corresponding to the sampling periods, and the like; />
Control signal representing the corresponding remote control unit, < >>
Is->
Control signals of remote control units corresponding to the sampling periods, and so on,/and so on>
Is->
And a control signal of the remote control unit corresponding to the sampling period.
27. A civil aircraft flight control system actuation loop fault diagnosis method is characterized by sequentially comprising the following steps:
step one, periodically and continuously collecting position signals of an actuator through a position sensor, correspondingly periodically and continuously collecting pressure signals of the actuator through a pressure sensor, and obtaining control signals of a corresponding remote control unit;
calculating the speed of the actuator and the output flow of the electrohydraulic servo valve by adopting an optimal estimation method according to the position signal of the actuator and the pressure signal of the actuator;
fitting a curve equation between the output flow of the electrohydraulic servo valve and the control signal of the remote control unit according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; according to the curve equation, calculating a control signal of a corresponding remote control unit when the electrohydraulic servo valve has zero flow;
Step four, identifying the dynamic characteristics of the electrohydraulic servo valve according to the output flow of the electrohydraulic servo valve calculated in a plurality of sampling periods and the control signal of the corresponding remote control unit; separating dynamic characteristics of the electro-hydraulic servo valve by adopting a separation method to separate undamped natural frequency of the electro-hydraulic servo valve and damping ratio of the electro-hydraulic servo valve;
and fifthly, comparing the calculated control signals of the corresponding remote control units, the undamped natural frequency of the separated electrohydraulic servo valve and the damping ratio of the separated electrohydraulic servo valve with the zero flow signals of the factory calibrated electrohydraulic servo valve, the undamped natural frequency of the factory calibrated electrohydraulic servo valve and the damping ratio of the factory calibrated electrohydraulic servo valve to obtain the health condition of the electrohydraulic servo valve.
28. The method for diagnosing faults in an actuation circuit of a flight control system of a civil aircraft as claimed in claim 27, wherein in the fifth step, the specific process of obtaining the health condition of the electro-hydraulic servo valve is as follows:
when the calculated value change between the control signal of the corresponding remote control unit and the factory calibrated zero flow signal of the electrohydraulic servo valve exceeds 10%, obtaining zero drift overrun of the electrohydraulic servo valve;
When the value change between the undamped natural frequency of the separated electrohydraulic servo valve and the undamped natural frequency of the electrohydraulic servo valve calibrated by a factory exceeds 40%, the clamping stagnation of the electrohydraulic servo valve is obtained;
and when the value change between the damping ratio of the separated electrohydraulic servo valve and the damping ratio of the electrohydraulic servo valve calibrated by a factory exceeds 40%, the clamping stagnation of the electrohydraulic servo valve is obtained.
29. The method for diagnosing a fault in an actuation circuit of a civil aircraft flight control system as claimed in claim 28, further comprising, after the fifth step, the following sequential steps:
step six, identifying dynamic characteristics of the actuating loop according to position signals of a plurality of sampling period actuators and control signals of corresponding remote control units; separating dynamic characteristics of the actuating circuit by adopting a separation method to separate undamped natural frequency of the actuating circuit and damping ratio of the actuating circuit;
and step seven, comparing the undamped natural frequency of the separated actuating circuit and the damping ratio of the separated actuating circuit with the undamped natural frequency of the actuating circuit calibrated by a factory and the damping ratio of the actuating circuit calibrated by the factory respectively to obtain the health condition of the actuating circuit.
30. The method for diagnosing a fault in an actuation circuit of a civil aircraft flight control system as claimed in claim 29, wherein in step seven, the specific process of obtaining the health condition of the actuation circuit is as follows:
and when the value change between the undamped natural frequency of the separated actuating circuit and the undamped natural frequency of the actuating circuit calibrated by the factory exceeds 40 percent or when the value change between the damping ratio of the separated actuating circuit and the damping ratio of the actuating circuit calibrated by the factory exceeds 40 percent, the actuating circuit fault is obtained.
31. A method for diagnosing a fault in an actuation circuit of a civil aircraft flight control system as claimed in claim 30, further comprising, after said step seven, the steps of:
and step eight, when the electro-hydraulic servo zero drift overrun is not obtained in the step five, the electro-hydraulic servo valve clamping stagnation is not obtained, and the actuating loop fault is obtained in the step seven, the actuator clamping stagnation is obtained.
32. The method for diagnosing faults in an actuation circuit of a flight control system of a civil aircraft as claimed in claim 31, wherein the best estimation method adopted in the second step is a kalman filter method of correction coefficient, and the speed of the actuator and the output flow of the electrohydraulic servo valve are calculated as follows:
First, the flow formula of the electrohydraulic servo valve is as follows:
the forward output flow of the electrohydraulic servo valve is as follows:
wherein ,
for the positive output flow of electrohydraulic servo valve, < >>
Is the flow coefficient; />
Is the density of the liquid; />
For the supply pressure>
For positive output pressure of electrohydraulic servo valve, < >>
For the area of the rod cavity of the actuator, +.>
Is the speed of the actuator;
the negative output flow of the electrohydraulic servo valve is as follows:
wherein ,
for the negative output flow of electrohydraulic servo valve, +.>
Is the flow coefficient; />
Is the density of the liquid; />
For the supply pressure>
For negative output pressure of electrohydraulic servo valve, +.>
Is the rodless cavity area of the actuator, +.>
Is the speed of the actuator;
secondly, linearizing the flow formula of the electrohydraulic servo valve by using a Taylor formula to obtain:
forward output flow of electrohydraulic servo valve:
/>
negative output flow of electrohydraulic servo valve:
wherein ,
for forward flow gain, +.>
In the form of increments of the control signal of the remote control unit, < >>
Is a positive pressure gain->
The positive output pressure of the electrohydraulic servo valve is increased; />
For negative flow gain, +.>
For negative pressure gain, +.>
Negative of electrohydraulic servo valveAn incremental form of output pressure;
again, from the actuator pressure model:
wherein ,
is the volume elastic modulus of oil liquid, +.>
Is the rodless cavity volume of the actuator, +.>
For the rod chamber volume of the actuator, +.>
For the position signal of the actuator,>
for the leakage coefficient of the rodless cavity of the actuator, +.>
For actuators with rod chamber leakage coefficient +.>
For the sampling period +.>
Is->
First derivative with respect to time;
the motion model of the actuator is established as follows:
wherein ,
representing the mass of the moving part in the actuator, +.>
Representing the motion damping coefficient of a moving part in the actuator, < + >>
Representing the elastic coefficient of a moving part in the actuator;
the state space model of the actuation circuit is built as follows:
wherein ,
is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time, < >>
Is->
First derivative with respect to time;
Finally, after a prediction process noise covariance matrix and a measurement process covariance matrix in Kalman filtering are set, a complete Kalman filtering model is obtained, kalman filtering is realized, and therefore the speed of the actuator and the output flow of the electrohydraulic servo valve are calculated.
33. The method for diagnosing faults in an actuation circuit of a flight control system of a civil aircraft according to claim 32, wherein in the third step, the output flow of the electro-hydraulic servo valve calculated according to a plurality of sampling periods and the control signal of the corresponding remote control unit are fitted to obtain the flow gain of the electro-hydraulic servo valve, and a curve equation between the output flow of the electro-hydraulic servo valve and the control signal of the remote control unit is a least square method, and the specific curve equation is as follows:
wherein ,
for the output flow of electrohydraulic servo valve, +.>
For the control signal of the remote control unit, +.>
For the flow gain of electrohydraulic servo valve, +.>
Is constant.
34. The method for diagnosing a fault in an actuation circuit of a pilot system of a civil aircraft as recited in claim 33, wherein in the fourth step, the dynamic characteristics of the electro-hydraulic servo valve are identified as follows:
wherein ,
is the undamped natural frequency of the electrohydraulic servo valve, < ->
Is the damping ratio of electrohydraulic servo valve, +.>
Law's transformation of the output flow of the electrohydraulic servo valve,>
law's transformation of control signals for a remote control unit,/->
Is a Laplacian operator;
the separation method adopts inverse transformation from Z domain to S domain to separate out undamped natural frequency of electrohydraulic servo valve 
Damping ratio with electrohydraulic servo valve>
。
35. The method for diagnosing faults in an actuation circuit of a civil aircraft flight control system as claimed in claim 34, wherein in step four, the non-damping natural frequency of the electro-hydraulic servo valve is separated by inverse transformation from Z domain to S domain
Damping ratio with electrohydraulic servo valve>
The specific process of (2) is as follows:
firstly, solving a discrete equation root Z corresponding to the dynamic characteristics of an electrohydraulic servo valve;
and converting the discrete equation root Z into a continuous domain root S, wherein the conversion formula is as follows:
wherein T is the sampling interval between sampling periods;
finally, the undamped natural frequency of the electrohydraulic servo valve can be obtained through the continuous domain root S
Damping ratio with electrohydraulic servo valve>
。
36. The method for diagnosing a fault in an actuation circuit of a civil aircraft flight control system according to claim 35, wherein in the fourth step, a discrete equation corresponding to a dynamic characteristic of the electrohydraulic servo valve is:
wherein ,
sampling period sequence number; />
Is the coefficient to be identified; />
The number of poles;
the number of the zero points; />
Delay beats; />
Position signal representing actuator->
Is->
Position signal of actuator corresponding to each sampling period, < +.>
Is- >
Position signals of actuators corresponding to the sampling periods, and the like; />
Control signal representing the corresponding remote control unit, < >>
Is->
Control signals of remote control units corresponding to the sampling periods, and so on,/and so on>
Is->
And a control signal of the remote control unit corresponding to the sampling period.
37. The method for diagnosing a fault in an actuation circuit of a civil aircraft flight control system as claimed in claim 36, wherein in the sixth step, the dynamic characteristics of the actuation circuit are identified as follows:
wherein ,
is the natural frequency of the damping-free of the actuation circuit, < ->
For the damping ratio of the actuation circuit, +.>
Lawster's transformation of the position signal for the actuator, < >>
Law's transformation of control signals for a remote control unit,/->
Is a Laplacian operator;
the separation method adopts inverse transformation from Z domain to S domain to separate out undamped natural frequency of the actuating loop
Damping ratio of the actuating circuit +.>
。
38. The method for diagnosing faults in an actuation circuit of a civil aircraft flight control system as claimed in claim 37, wherein in said step six, the non-damped natural frequency of the actuation circuit is separated by inverse transformation of the Z domain to the S domain
Damping ratio of the actuating circuit +. >
The specific process of (2) is as follows:
firstly, solving a discrete equation root Z corresponding to dynamic characteristics of an actuating loop;
and converting the discrete equation root Z into a continuous domain root S, wherein the conversion formula is as follows:
wherein T is the sampling interval between sampling periods;
finally, the undamped natural frequency of the actuating loop can be obtained through the continuous domain root S
Damping ratio of the actuating circuit
。
39. The method for diagnosing a fault in an actuation circuit of a civil aircraft flight control system as claimed in claim 38, wherein in the sixth step, the discrete equation corresponding to the dynamic characteristics of the actuation circuit is:
wherein ,
sampling period sequence number; />
Is the coefficient to be identified; />
The number of poles;
the number of the zero points; />
Delay beats; />
Position signal representing actuator->
Is->
Position signal of actuator corresponding to each sampling period, < +.>
Is->
Position signals of actuators corresponding to the sampling periods, and the like; />
Control signal representing the corresponding remote control unit, < >>
Is->
Control signals of remote control units corresponding to the sampling periods, and so on,/and so on>
Is->
And a control signal of the remote control unit corresponding to the sampling period. />
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