CN113820054B - Train rigid bow net contact force all-fiber measurement method and system - Google Patents
Train rigid bow net contact force all-fiber measurement method and system Download PDFInfo
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- G01L1/00—Measuring force or stress, in general
- G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
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Abstract
The application discloses a train rigid bow net contact force all-fiber measuring method and a system, comprising the following steps: the technology of the application realizes the inversion measurement of the bow net contact force based on the optical fiber measurement and the optimized inversion calculation of the dynamic response of the contact net, is a novel bow net contact force measurement technology, and has the advantages of simple structure to be measured and stress (no aerodynamic action), single type of required sensors, electromagnetic interference resistance of a sensing system, small influence on the dynamic characteristic of the structure to be measured, small noise interference of track vibration to measurement and the like compared with the traditional indirect measurement technology based on the dynamic response of the pantograph net, so that the indirect measurement precision of the bow net contact force can be improved.
Description
Technical Field
The application relates to the technical field of rail transit, in particular to a method and a system for measuring a rigid bow net contact force of a train by all optical fibers.
Background
The train pantograph system is a device for realizing electric energy transmission from a substation to a train to drive the train to run, comprises an overhead contact system and a pantograph arranged on the roof of the train, and the safety and reliability of the train pantograph system are important guarantees for determining the stable running of the train. Contact networks are divided into flexible contact networks and rigid contact networks. The flexible contact net is mainly used for rapid rail transit of high-speed rails and the like; the rigid contact net is an overhead beam structure, has high rigidity compared with a flexible contact net, is supported by a fixed suspension mechanism which is periodically arranged, has the advantages of relatively simple structure, wind resistance, low construction and maintenance cost and the like, is suitable for urban rail lines including subways and intercity rail transit, and is also suitable for main railways with higher tunnel occupation.
The train speed of the existing rigid contact net is restricted, and the key influence factor is the fluctuation of the bow net contact force, which is the embodiment of bow net coupling vibration. The fluctuation of the pantograph-catenary contact force is increased along with the increase of the train speed, so that the current receiving pulsation of the train is increased, the current receiving quality is reduced, the pantograph-catenary is separated and an arc discharge phenomenon is generated in severe cases, the pantograph-carbon sliding plate and a contact net are partially ablated, and the current receiving quality is further reduced. Thus, fluctuations in the bow net contact force (variance and maxima, minima) are a major performance indicator of rigid bow net systems.
Accurate measurement of bow-net contact force is a prerequisite for its control. The traditional bow net contact force measurement is indirectly obtained through the measurement of the supporting force and the dynamic response of a carbon pantograph slider on the roof of a train, the stress and the dynamic response signal of the carbon slider are measured through force transducers additionally arranged at two ends of the carbon slider and acceleration or strain transducers in the force transducers, and the bow net contact force is indirectly measured through the balance relation among the supporting force, the aerodynamic force, the inertial force and the bow net contact force of the carbon slider. Generally, the carbon sliding plate is regarded as a rigid body or an elastic body, and the change of the contact point position on the carbon sliding plate needs to be measured synchronously, so that the mechanical quantity and the type of a sensing system thereof need to be measured more. Meanwhile, the distribution force of the aerodynamic force on the carbon sliding plate is difficult to directly measure and needs to be estimated by an empirical formula, so that the measurement of the bow net contact force has certain mechanical approximation. In addition, rail vibrations are transmitted to the pantograph via the roof of the vehicle, so that the measurement of the pantograph-catenary contact force is disturbed by relatively significant rail vibration noise. And the sensors are generally electric sensors which are easily influenced by the high-voltage electromagnetic working environment of the pantograph net, so the sensors can normally work on the pantograph only by shielding and packaging, extra mass is added to the carbon sliding plate and the pantograph, and the dynamic characteristics of the carbon sliding plate and the structural dynamic response distortion are caused.
Disclosure of Invention
In order to solve the problem of mechanical, sensor and track vibration interference existing in the traditional bow net contact force measuring method, the application provides a train rigid bow net contact force all-fiber measuring method and system, and the method and system can be applied to measurement of the contact force of a rigid bow net system in a laboratory or an actual line detection section.
According to an aspect of the embodiments of the present application, there is provided an all-fiber measurement method for a rigid bow net contact force of a train, including:
measuring the bending strain dynamic response of discrete points of a contact network by using an optical fiber sensor string;
determining a preset contact force parameter of the current bow net of the train;
calculating the deflection dynamic response of the contact net corresponding to the preset contact force parameter according to the established dynamic equation of the contact net under the contact force excitation in the pantograph-catenary system of the train;
calculating the bending strain at the measuring point of the catenary based on the calculated catenary deflection dynamics response, and comparing the bending strain with the measuring point bending strain dynamics response measured by the optical fiber strain sensor to calculate the bow net contact force inversion error;
and correcting the pantograph contact force parameters from the pantograph contact force inversion error according to an optimization algorithm to obtain candidate contact force parameters of the current train pantograph net, and repeating the inversion calculation by taking the current candidate contact force parameters as new preset contact force parameters. And under the condition that the candidate contact force parameter meets a preset error condition of bow net contact force inversion, determining the candidate contact force parameter as a target contact force parameter.
Further, the measuring of the bending strain dynamic response of the discrete points of the catenary according to the optical fiber sensor string includes:
the method comprises the steps of measuring beam bending strain at a plurality of discrete measurement points on the contact net by using a plurality of Fiber Bragg Grating (FBG) sensor strings, and determining the beam bending strain as a measurement value of the bending strain dynamic response.
Further, the calculating of the deflection dynamic response of the catenary corresponding to the preset contact force parameter according to the established dynamic equation of the contact net under excitation of the contact force of the pantograph-catenary in the pantograph-catenary system of the train comprises:
according to a contact net kinetic equation under contact force excitation in a train pantograph-catenary system, the kinetic equation is as follows:
in the formula, Y (x, t) is the deflection of the beam; ρ (x) and A (x) are the bulk density and cross-sectional area of the beam; (x) is the damping coefficient of the material; e (x) represents the modulus of elasticity of the beam; i (x) is the beam section moment of inertia; m is j And k j Mass and stiffness, x, of the equivalent spring of the suspension mechanism, respectively j (j is 1, N) is the spring position coordinate, N is the total number of springs, δ (x) is the dirac function; f. of c (t) and x c (t) distribution functions of contact force magnitude and contact position changing with time obtained by interpolation of contact force parameters respectively;
and inputting the contact force expressed by the preset contact force parameter and the contact position function into the kinematic equation to obtain the deflection dynamic response of the overhead contact system.
Further, a reconstruction value of the bending strain dynamic response at a measuring point of the overhead line system is calculated based on the deflection dynamic response of the overhead line system, and is compared with a corresponding measurement value of the bending strain dynamic response at the measuring point of the optical fiber strain sensor, and the difference between the two is calculated to be used as an inversion error of the contact force of the pantograph-catenary, wherein the method comprises the following steps:
calculating a reconstruction value epsilon of bending strain dynamic response at a contact net measuring point based on the contact net deflection dynamic response R Represented by the following formula:
in the formula, h (x) k ) For measuring point x of contact net k The height from the mounting point of the sensor to the neutral plane of the equivalent beam of the contact network, M is the total number of strain measuring points of the contact network, b tI And
the contact force parameter vector is a component of the contact force parameter vector, and the component of the contact force parameter vector respectively represents the moment when the pantograph reaches the given different identification points and the magnitude of the contact force;
calculating a bow net contact force inversion error according to the measured value and the reconstructed value of the bending strain at the measuring point, wherein the calculation formula of the bow net contact force inversion error is as follows:
in the formula, epsilon M (x k T) is the measured value of the bending strain at the measuring point, and T is the total measuring period.
Further, the bow net contact force parameter is corrected from the bow net contact force inversion error according to an optimization algorithm to obtain a candidate contact force parameter of the current train bow net, and the current candidate contact force parameter is used as a new preset contact force parameter to repeat the inversion calculation; determining the candidate contact force parameter as a target contact force parameter under the condition that the candidate contact force parameter meets a preset error condition of bow net contact force inversion, wherein the step of determining the candidate contact force parameter comprises the following steps:
calculating by taking bow net contact force and contact time parameters as optimization variables to enable the inversion error of the bow net contact force to take the minimum value:
and correcting the bow net contact force parameter according to the optimization algorithm from the bow net contact force inversion error to obtain the current contact force parameter of the train bow net as a new preset contact force parameter, repeating the inversion calculation, and determining the current candidate contact force parameter as a target contact force parameter under the condition that the bow net contact force inversion error meets a preset error condition through iterative operation, thereby obtaining the contact force and the time course change of the contact position.
Further, the method further comprises:
dividing the total measurement time period to obtain a plurality of time measurement intervals;
according to the time sequence of the time measurement intervals, performing optimization iterative calculation on contact force parameters corresponding to the time measurement intervals until the error value is converged;
the piecewise optimization calculation formula is as follows:
where Q is the number of time measurement zones, M i The total number of the measuring points of the ith section;
the k-th measuring point coordinate of the ith segment;
and (c) and (d),
identifying parameter component vectors of contact time and contact force of the ith section; t is t i-1 And t i Respectively the start and end times of the ith segment.
According to another aspect of the embodiments of the present application, there is provided an all-fiber measurement system for a rigid bow net contact force of a train, including: a pantograph, a contact network and a measuring device;
the bottom of the pantograph is mounted at the top of the train, the top of the pantograph is in sliding connection with the overhead line system so that the overhead line system supplies electric energy to the pantograph, and an optical fiber sensor in the measuring device is mounted on discrete measuring points of the overhead line system;
wherein, the contact net includes: the contact wire is embedded in the busbar, and the supporting structure is arranged on the outer side of the busbar and used for supporting the busbar.
Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages: according to the embodiment of the application, the response of the bending dynamics of the rigid contact net is measured, and the inverse problem of the structural dynamics is used for solving the inverse pantograph-catenary contact force. Because the structure and the stress of the measured structural object are simple, the inversion precision of the contact force can be improved from mechanics; in addition, the required measurement variables are single in type, so that a sensing system is simplified, and the influence on the dynamic characteristics of a measured structural object is reduced while measuring a large number of measuring points by adopting the optical fiber sensor which is small in size, light in weight and resistant to electromagnetic interference; meanwhile, the influence of the track vibration is transmitted to the contact network through the contact force which is the measured signal, so that the contribution of the track vibration to the target contact force is reserved, and the interference of the track vibration serving as noise to the working of the sensor in the traditional measuring method is avoided.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and, together with the description, serve to explain the principles of the application.
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious for those skilled in the art to obtain other drawings without inventive labor.
Fig. 1 is a flowchart of an all-fiber measurement method for a rigid bow net contact force of a train according to an embodiment of the present disclosure;
fig. 2 is a schematic diagram of an FBG optical fiber sensing system according to an embodiment of the present disclosure;
fig. 3 is a block diagram of an all-fiber measurement system for a rigid bow net contact force of a train according to an embodiment of the present disclosure;
fig. 4 is a schematic structural diagram of an all-fiber measurement system for a rigid bow net contact force of a train according to an embodiment of the present application.
Detailed Description
In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application, it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments, and the illustrative embodiments and descriptions thereof of the present application are used for explaining the present application and do not constitute a limitation to the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
According to an aspect of the embodiments of the present application, an embodiment of a method for a full optical fiber measurement method for a rigid bow net contact force of a train is provided. Fig. 1 is a flowchart of an all-fiber measurement method for a contact force of a rigid bow net of a train according to an embodiment of the present application, and as shown in fig. 1, the method includes:
and S11, measuring the bending strain dynamic response of the discrete measuring points of the overhead line system by using the optical fiber sensor string.
In this application embodiment, the bending strain dynamic response of the discrete measuring point of the catenary measured by the optical fiber sensor string includes: the method comprises the steps of measuring beam bending strain at a plurality of discrete measuring points on a contact network by using a plurality of Fiber Bragg Grating (FBG) sensor strings, and determining the beam bending strain as a measured value of the bending strain dynamic response.
The embodiment of the application adopts the FBG sensor string to measure the dynamic bending strain of discrete measuring points on the rigid contact net beam. The FBG strings are pasted on a contact network busbar (the top or the side), and quasi-distributed measurement of beam bending strain is realized through FBG strain measurement information in discrete distribution. As shown in fig. 2, the FBG optical fiber sensing system comprises: the FBG sensor comprises an FBG sensor string, an optical fiber lead wire and a wavelength demodulator, wherein the wavelength demodulator is used for emitting laser, receiving the laser reflected from each sensor and distinguishing the wavelength of the laser; the digital signal of the wavelength information is transmitted to a computer for collection through a network cable.
The FBG optical fiber sensor is adopted to measure, and the beneficial effects are as follows:
1) the device has the advantages that the device is capable of optical measurement of wavelength modulation and electromagnetic interference resistance, is particularly suitable for high-voltage electromagnetic working environment of a rigid contact net, and does not need shielding protection;
2) the FBG can be used as a sensing element to directly measure strain;
3) by adopting the wavelength division multiplexing technology, the series measurement of the sensors can be realized, and the wiring complexity is greatly simplified;
4) the size is small, the weight is light, and the dynamic characteristics of the contact net structure are not influenced.
Therefore, the all-fiber measurement adopted by the invention is superior to the traditional electric measurement technology (or partially adopted) based on pantograph dynamic response indirect measurement in the sensing precision, and the measurement precision of the pantograph-catenary contact force is further improved from the sensing technology.
And step S12, determining the preset contact force parameter of the current pantograph net of the train.
And step S13, calculating the deflection dynamic response of the contact net corresponding to the preset contact force parameter according to the dynamic equation of the contact net under the contact force excitation in the established pantograph-catenary system of the train.
In this embodiment of the present application, in step S13, calculating a deflection dynamic response of the catenary corresponding to a preset contact force parameter according to an established dynamic equation of the contact net under contact force excitation in the pantograph-catenary system of the train, including the following steps a1-a 2:
step A1, establishing a dynamic equation of the contact net under contact force excitation in the train bow net system, wherein the dynamic equation is as follows:
in the formula, Y (x, t) is the deflection of the beam; ρ (x) and A (x) are the bulk density and cross-sectional area of the beam; (x) is the damping coefficient of the material; e (x) represents the modulus of elasticity of the beam; i (x) is the beam section moment of inertia; m is j And k j Mass and stiffness, x, of the equivalent spring of the suspension mechanism, respectively j (j is 1, N) is the spring position coordinate, N is the total number of springs, δ (x) is the dirac function; f. of c (t) and x c (t) distribution functions of contact force magnitude and contact position changing with time obtained by interpolation of contact force parameters respectively;
and A2, inputting the contact force expressed by the preset contact force parameter and the contact position function into the kinematic equation to obtain the deflection dynamic response of the overhead contact system.
In the present embodiment, the structural dynamic response may be structural displacement or strain, etc. If a structural response is given, solveBow net contact force f c (t) and contact position x c (t) constitutes the inverse problem of the dynamics, which the present application converts into an optimization problem solution.
And S14, calculating a reconstruction value of the bending strain dynamic response at the measuring point of the catenary based on the catenary deflection dynamic response, comparing the reconstruction value with the measured value of the bending strain dynamic response at the measuring point of the optical fiber strain sensor, and calculating the bow net contact force inversion error.
In the embodiment of the application, in step S14, a reconstruction value of a bending strain dynamic response at a measurement point of the catenary is calculated based on the catenary deflection dynamic response, and compared with a measured value of the bending strain dynamic response at the measurement point of the optical fiber strain sensor, an inversion error of a bow-net contact force is calculated, and the method includes the following steps B1-B2:
step B1, calculating a reconstruction value of the bending strain dynamic response at the measuring point of the catenary based on the catenary deflection dynamic response, and calculating a reconstruction value epsilon of the bending strain at the measuring point R The formula of (1) is as follows:
in the formula, h (x) k ) For measuring point x of contact net k The height between the mounting point of the sensor and the neutral plane of the equivalent beam of the contact network is determined;
step B2, calculating a bow net contact force inversion error according to the measured value and the reconstructed value of the bending strain at the contact net measuring point, wherein the calculation formula of the bow net contact force inversion error is as follows:
in the formula, epsilon M (x k T) is the measured value of the bending strain of the measuring point, and T is the total measuring time interval.
Step S15, correcting the bow net contact force parameter according to the optimization algorithm from the bow net contact force inversion error to obtain a candidate contact force parameter of the current train bow net, and repeating the inversion calculation by taking the current candidate contact force parameter as a new preset contact force parameter; and determining the candidate contact force parameter as a target contact force parameter under the condition that the candidate contact force parameter meets a preset error condition of bow net contact force inversion.
In this embodiment, step S15 specifically includes:
calculating by taking bow net contact force and contact time parameters as optimization variables to enable the inversion error of the bow net contact force to take the minimum value:
and correcting the bow net contact force parameter according to the optimization algorithm from the bow net contact force inversion error to obtain the current contact force parameter of the train bow net as a new preset contact force parameter, repeating the inversion calculation, and determining the current candidate contact force parameter as a target contact force parameter under the condition that the bow net contact force inversion error meets a preset error condition through iterative operation, thereby obtaining the contact force and the time course change of the contact position.
The measurement principle adopted in the embodiment of the application is as follows: the multi-point bending strain dynamic response of the rigid catenary is measured, and then the pantograph-catenary contact force is inverted from the strain dynamic response based on the dynamic equation of the rigid catenary. According to the technology, other mechanical quantities do not need to be measured, the inversion calculation does not involve aerodynamic force, the contact network is simple in structure, and the inversion precision is high. And finally, the inversion calculation is converted into an optimization problem by taking the bow net contact force parameter as a design variable and taking the bow net contact force inversion error as a target function, and the bow net contact force parameter which enables the bow net contact force inversion error to take the minimum value is sought.
In the embodiment of the present application, the optimization algorithm in step S15 further includes the following steps C1-C2:
step C1, correcting the bow net contact force parameter from the bow net contact force inversion error by applying a common optimization algorithm to obtain a candidate contact force parameter of the bow net of the current train as a preset contact force parameter;
and C2, repeating the solution of the kinetic equation and the calculation of the inversion error of the bow net contact force, determining that the candidate contact force parameter meets the preset convergence condition of the inversion calculation under the condition that the error value falls into the inversion error condition, and determining the candidate contact force parameter as the target contact force parameter.
In the embodiment of the application, the optimization calculation can be performed in a segmented recursion manner, so that segmented identification or mobile identification of the bow net contact force is realized, and the contact force identification efficiency is improved.
In the embodiment of the present application, the optimization in step S15 may be performed in segments, including the following steps D1-D2:
step D1, obtaining a plurality of time measurement intervals obtained by dividing the total measurement time interval;
d2, according to the time sequence of the time measurement intervals, carrying out optimization iterative computation on the contact force parameters corresponding to the time measurement intervals until the error value is converged;
the piecewise optimization calculation formula is as follows:
where Q is the number of time measurement zones, M i The total number of the measuring points of the ith section;
the k-th measuring point coordinate of the ith segment;
and the combination of (a) and (b),
identifying parameter component vectors of contact force and contact time of the ith section; t is t i-1 And t i Respectively the start and end times of the ith segment.
The optimization problem in the embodiment of the application can be solved through optimization algorithms such as genetic algorithm or gradient method, and parameter vectors are given
And (c) and (d),
the initial value of (i) is calculated by adopting interpolation analysis c (t) and contact position x c (t); then solving a kinetic equation by a finite element method or a modal method, and calculating the reconstruction strain of the measuring point; segmented error functional E when reconstructing strain and measuring strain i When the accuracy is converged below a certain precision, the optimization calculation of the ith section is finished, contact force and contact position parameters are output, and then the optimization of the next section is carried out; if not, the parameter vector is adjusted through the optimization algorithm
And the combination of (a) and (b),
the above calculation is repeated. Therefore, the optimization solving process is actually an iterative solution for converting the inverse problem of load identification into the positive problem, the algorithm is simple and effective to realize, and the singularity problem existing in the inversion of the general inverse problem can be avoided.
As shown in fig. 3, an embodiment of the present application provides an all-fiber train bow net contact force measurement system, including: a pantograph 51, a catenary 52, and a measuring device 53;
one end of the pantograph 51 is arranged at the top of the train, the other end of the pantograph 51 is in sliding connection with the contact network 52, so that the contact network 52 provides electric energy for the pantograph, and the measuring device is mechanically connected with the contact network 52;
wherein, as shown in fig. 4, the overhead line system 52 includes: the bus bar comprises a bus bar 10, a contact wire 20 and a support structure 30, wherein the contact wire is embedded in the bus bar, and the support structure is arranged outside the bus bar and used for supporting the bus bar.
The above description is only for the preferred embodiment of the present application, and is not intended to limit the scope of the present application. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application are included in the scope of protection of the present application.
The above description is merely exemplary of the present application and is presented to enable those skilled in the art to understand and practice the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (7)
1. The full optical fiber measurement method for the contact force of the rigid bow net of the train is characterized by comprising the following steps:
measuring the bending strain dynamic response of discrete points of a contact network by using an optical fiber sensor string;
determining a preset contact force parameter of the current bow net of the train;
calculating the deflection dynamic response of the contact net corresponding to the preset contact force parameter according to the established dynamic equation of the contact net under the contact force excitation in the pantograph-catenary system of the train;
calculating the bending strain at the measuring point of the catenary based on the calculated catenary deflection dynamic response, and comparing the bending strain with the measuring point bending strain dynamic response measured by the optical fiber strain sensor to calculate the bow net contact force inversion error;
correcting the pantograph contact force parameters from the pantograph contact force inversion error according to an optimization algorithm to obtain candidate contact force parameters of the current train pantograph net, and repeating the inversion calculation by taking the current candidate contact force parameters as new preset contact force parameters; and determining the candidate contact force parameter as a target contact force parameter under the condition that the candidate contact force parameter meets a preset error condition of bow net contact force inversion.
2. The method of claim 1, wherein measuring a bending strain dynamic response of a discrete point of a catenary from a fiber optic sensor string comprises:
and measuring the beam bending strain at a plurality of discrete measuring points on the contact network by using a plurality of fiber Bragg grating sensor strings, and determining the beam bending strain as a measured value of the bending strain dynamic response.
3. The method of claim 1, wherein the calculating of the dynamic response of the deflection of the catenary corresponding to the preset contact force parameter according to the established dynamic equation of the contact net under excitation of the contact force of the pantograph-catenary in the pantograph-catenary system of the train comprises:
according to a contact net kinetic equation in a train pantograph-catenary system under excitation of pantograph-catenary contact force, the kinetic equation is as follows:
in the formula, Y (x, t) is the deflection of the beam; ρ (x) and A (x) are the bulk density and cross-sectional area of the beam; (x) is the damping coefficient of the material; e (x) represents the modulus of elasticity of the beam; i (x) is the beam section moment of inertia; m is a unit of j And k j Mass and stiffness, x, of the equivalent spring of the suspension mechanism, respectively j (j is 1, N) is the spring position coordinate, N is the total number of springs, δ (x) is the dirac function; f. of c (t) and x c (t) distribution functions of contact force magnitude and contact position changing with time obtained by interpolation of contact force parameters respectively;
and inputting the contact force expressed by the preset contact force parameter and the contact position function into the kinetic equation to obtain the deflection kinetic response of the overhead contact system.
4. The method of claim 1, wherein a reconstructed value of a bending strain dynamic response at a catenary measurement point is calculated based on the deflection dynamic response of the catenary, and compared with a measured value of the bending strain dynamic response at a fiber strain sensor measurement point, and a difference between the two is calculated as a bow net contact force inversion error, the method comprising:
calculating the bending stress change at the contact net measuring point based on the contact net deflection dynamic responseReconstructed value epsilon of mechanical response R Represented by the following formula:
in the formula, h (x) k ) For measuring point x of contact net k The height from the mounting point of the sensor to the neutral plane of the equivalent beam of the contact network, M is the total number of strain measuring points of the contact network,
and
the contact force parameter vector is a contact force parameter vector, and the components of the contact force parameter vector respectively represent the moment when the pantograph reaches given different identification points and the magnitude of the contact force;
calculating a bow net contact force inversion error according to the measured value and the reconstructed value of the bending strain at the measuring point, wherein the calculation formula of the bow net contact force inversion error is as follows:
in the formula, epsilon M (x k T) is the measured value of the bending strain at the measuring point, and T is the total measuring time period.
5. The method of claim 4, wherein the bow net contact force parameter is corrected from the bow net contact force inversion error according to an optimization algorithm to obtain a candidate contact force parameter of the current train bow net, and the inversion calculation is repeated with the current candidate contact force parameter as a new preset contact force parameter; determining the candidate contact force parameter as a target contact force parameter under the condition that the candidate contact force parameter meets a preset error condition of bow net contact force inversion, wherein the step of determining the candidate contact force parameter comprises the following steps:
calculating by taking bow net contact force and contact time parameters as optimization variables to enable the inversion error of the bow net contact force to take the minimum value:
and correcting the bow net contact force parameter according to the optimization algorithm from the bow net contact force inversion error to obtain the current contact force parameter of the train bow net as a new preset contact force parameter, repeating the inversion calculation, and determining the current candidate contact force parameter as a target contact force parameter under the condition that the bow net contact force inversion error meets a preset error condition through iterative operation, thereby obtaining the contact force and the time course change of the contact position.
6. The method of claim 5, further comprising:
dividing the total measurement time period to obtain a plurality of time measurement intervals;
according to the time sequence of the time measurement intervals, performing optimization iterative calculation on the contact force parameters corresponding to the time measurement intervals until the error value is converged;
the piecewise optimization calculation formula is as follows:
where Q is the number of time measurement zones, M i The total number of the measuring points of the ith section;
the k-th measuring point coordinate of the ith segment;
and the combination of (a) and (b),
contact time and contact force identification of section iDividing the parameters into vectors; t is t i-1 And t i Respectively the start and end times of the ith segment.
7. An all-fiber measurement system for train rigid bow net contact force, which applies the all-fiber measurement method for train rigid bow net contact force according to any one of claims 1 to 6, and is characterized by comprising the following steps: a pantograph, a contact network and a measuring device;
the bottom of the pantograph is mounted at the top of the train, the top of the pantograph is in sliding connection with the overhead line system so that the overhead line system supplies electric energy to the pantograph, and an optical fiber sensor in the measuring device is mounted on discrete measuring points of the overhead line system;
wherein, the contact net includes: the contact wire is embedded in the busbar, and the supporting structure is arranged on the outer side of the busbar and used for supporting the busbar.
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