Control model acquisition method and system for compactness on-line monitoring in asphalt mixture paving construction process, controller and control method

Abstract

A control model acquisition method and system, a controller and a control method for compactness online monitoring in an asphalt mixture paving construction process, comprising the steps of: step 100: establishing a paving system dynamics model, step 200: establishing an acceleration signal detection system, step 300: establishing signal filtering noise reduction, step 400: establishing field calibration and online monitoring, and step 400: establishing an acceleration signal detection system, step 400: establishing an acceleration signal detection system, step 400: establishing an acceleration signal detection system, and step 400: establishing an acceleration signal detection system. Modeling analysis is carried out on corresponding dynamic characteristics of a vibrating mechanism and a vibrating mechanism by constructing a dynamic model of the compaction system, and a screed acceleration signal measurement and acquisition system is constructed based on the modeling analysis, so that a vibration signal filtering processing method is provided, and an effective acceleration analysis signal is provided; a numerical model is established through measurement and calibration to realize on-line monitoring of the paving compactness of the asphalt mixture, and operation parameters of a vibrating mechanism are guided based on a kinetic model.

Description

1. Technical Field

[0001] The present invention relates to a control model acquisition method and system, a controller and a control method, and in particular to a control model acquisition method and system, a controller and a control method for online monitoring of the density of an asphalt mixture paving construction process. 2. Background Technology

[0002] The density of asphalt mixture paving affects the final quality of asphalt pavement. Insufficient paving density will cause waves to appear on the asphalt pavement during compaction, resulting in low pavement flatness and even affecting the final density of the pavement.

[0003] The existing online density detection has made great progress, but it is mainly used in combination with vibratory rollers to monitor the compaction quality during the asphalt mixture compaction process. There is a lack of research on the online density detection of asphalt mixture paving.

[0004] The dynamic model of the screed plate is an important tool for studying the interaction between the screed plate and the asphalt mixture during the screed plate paving process. It has gradually been equipped with mechanisms such as double rammers plus double pressure beams and vibration units, and the force conditions are complex. The current research on the force conditions of the screed plate is mostly focused on the dynamic model when the screed plate is only subjected to vibration and when the screed plate is only subjected to vibration. The online monitoring technology of the complex vibration system still needs further breakthroughs. The current research on the technology of online detection of the paving density in the paving process cannot accurately reflect the density of the asphalt mixture paving construction process.

[0005] Based on the applicant's technical briefing document dated July 6, 2024 and the existing technical problems, technical features and technical effects in similar background technologies obtained through retrieval, the technical application scheme of the present invention was made. III. Summary of the invention

[0006] The object of the present invention is a control model acquisition method for online monitoring of density during asphalt mixture paving construction.

[0007] The object of the present invention is a control model acquisition system for online monitoring of density during asphalt mixture paving construction.

[0008] The object of the present invention is a controller for online monitoring of the density of asphalt mixture paving construction process.

[0009] The object of the present invention is a control method for online monitoring of the density during the asphalt mixture paving construction process.

[0010] In order to overcome the above-mentioned technical shortcomings, the purpose of the present invention is to provide a control model acquisition method and system, controller and control method for online monitoring of the density of asphalt mixture paving construction process, thereby establishing a model that simulates the change signal of the vertical acceleration of the ironing plate to reflect the density of the paving layer.

[0011] In order to achieve the above object, the technical solution adopted by the present invention is:

[0012] A control model acquisition method for online monitoring of density during asphalt mixture paving construction, the steps of which are:

[0013] The steps are:

[0014] Step 100: Establish a paving system dynamics model.

[0015] Step 200: Establish an acceleration signal detection system.

[0016] Step 300: Establish signal filtering and noise reduction,

[0017] Step 400: Establish on-site calibration and online monitoring.

[0018] Due to the design of the above steps, by constructing the dynamic model of the compaction system, the dynamic corresponding characteristics of the vibrating mechanism and the vibration mechanism are modeled and analyzed respectively. Based on this, the ironing plate acceleration signal measurement and acquisition system is constructed, and then the vibration signal filtering processing method is proposed, and the effective acceleration analysis signal is proposed. Through measurement and calibration, a numerical model is established to realize the online monitoring of the asphalt mixture paving density, and the operating parameters of the vibrating mechanism are guided based on the dynamic model.

[0019] The present invention designs: (1) a vibration mechanism action model

[0020] Vibration has the characteristics of compaction and vibration compaction, but the vibration energy is weak, the energy of a single vibration decays quickly, and the vibration stroke is high and the impact interval is large. Therefore, multiple vibrations are regarded as intermittent periodic rectangular shock waves. The periodic vibration shock waves are shown in the attached figure. Figure 3 As shown,

[0021] The response function of the vibration compaction system is an attenuation signal (Formula (1-1)).

[0022]

[0023] α is the pulse width coefficient, which is 1 / 3T, the pulse height is E, and the vibration period is T.

[0024] The vibration excitation period is expressed using Fourier series:

[0025]

[0026] The spectrum of periodic vibration shock wave is shown in the attached figure. Figure 4 As shown,

[0027] The eccentric positions of the main and auxiliary vibrators differ by 180°. It can be considered that the vibrating hammers move in parallel without constraints in the vertical direction. The model can be simplified as shown in the attached figure. Figure 5 The double vibrating compaction mechanism model shown in the figure is Attached Figure 5 middle: O1 and O2 are the centroids of the main and auxiliary eccentric sleeves respectively; O is the rotation center of the eccentric shaft; θ1 is the initial phase angle of the auxiliary vibrator; θ2 is the initial phase angle of the main vibrator; r1 is the eccentricity of the auxiliary vibrator on the eccentric shaft; r2 is the eccentricity of the main vibrator on the eccentric shaft; m1 is the mass of the auxiliary vibrator; m2 is the mass of the main vibrator; ω d ——Eccentric shaft speed; x——Displacement of the ironing plate; x1——Displacement of the auxiliary vibrator, x1=x+r r sin(ω d t); x2——displacement of the main vibrator, x2=x+r2 sin(ω d t+2π),

[0028] The dynamic equation of the vibrator is obtained by Fourier transform:

[0029]

[0030] Among them, f d1 and f d2 is the force exerted by the eccentric shaft on the main and auxiliary vibrators; k1, c1, k2, c2 are the stiffness coefficient and damping coefficient of the ply material under the main and auxiliary vibrators.

[0031] When the eccentric block contacts the pavement, the vibration force reaches the maximum value m1r1ω 2 d , and compact the pavement at the same time, the response acceleration, velocity and displacement of the vibrator can be obtained:

[0032]

[0033] According to the interaction principle between the vibrating mechanism and the ironing plate, combined with formula (1-3), the force R (t) exerted by the vibrator on the plate can be obtained as follows:

[0034]

[0035] (2) Vibration compaction mechanism action model

[0036] The vibration compaction model is shown in the attached Figure 6 , Attached Figure 6 middle: m——mass of the screed box, kg; m0——mass of two eccentric shafts with the same rotation speed but opposite rotation directions, kg; ω——angular velocity of the vibrator during rotation, rad / s; t——rotation time, s

[0037] In order to better offset the influence of centrifugal force in the horizontal direction on the pavement paving quality, the symmetry line of the rotation center of the two eccentric shafts is made to pass vertically through the inertia center of the entire ironing plate; for the convenience of calculation and analysis, it is assumed that the resultant force exerted on the ironing plate by the material stiffness k and damping c at the bottom of the ironing plate passes through the center of mass of the ironing plate, and the moment of the force system composed of the exciting force and the supporting force on the center of mass is zero.

[0038] The dynamic differential equation of the screed is:

[0039]

[0040] k is the support stiffness coefficient of the medium; c is the resistance coefficient; x is the longitudinal displacement of the ironing board; Q(t) is the excitation generated by the rotation of the eccentric mass, Q(t) = 2m0rω 2 sin(ωt); r is the rotation radius; R(t) is the force exerted by the vibrator on the ironing plate.

[0041] Substituting equation (1-7) into equation (1-8), equation (1-9) constructs the acceleration of the screed plate and the angular velocity ω of the vibrating mechanism and the vibrating structure, ω d And the relationship between asphalt mixture properties k and c.

[0042]

[0043] Where:

[0044] M=m+2m0+m1+m2↓

[0045] C=c+c1+c2↓

[0046] K=k+k1+k2

[0047]

[0048] A5=2m0rω 2

[0049] The present invention is designed that, as can be seen from formula (1-9), the dynamic characteristics of the vibrating mechanism and the ironing plate can be directly measured by acceleration, and existing studies have shown that there is a certain correlation between the stiffness of the pressed material and the vibration acceleration. Therefore, the vibration dynamic parameters mainly based on the vibration acceleration can be analyzed to indirectly obtain the paving density. The density of the paving layer is reflected by using the change in the acceleration of the ironing plate in the vertical direction.

[0050] The basic principle of the online paving density detection system is as follows: Figure 7 As shown,

[0051] (1) Signal measurement module

[0052] The sensor used should meet the construction requirements, be able to withstand temperatures of 110-120°C, and the acceleration measurement amplitude should not be less than 20m / s 2 It has the characteristics of high sensitivity and anti-interference. The installation position is on the ironing board below the middle part of the paver. The installation position of the acceleration sensor is as shown in the attached Figure 8 As shown,

[0053] (2) Signal acquisition module

[0054] The acquisition card should have an acceleration sensor drive unit, and integrate a DC isolation circuit and a charge amplifier for basic processing functions such as signal isolation and amplification. It should have a 16-bit ADC and a vibration signal acquisition frequency of 5kHz.

[0055] (3) Signal processing module

[0056] The signal processing module has the functions of time domain and frequency domain transformation, which can obtain signal characteristics such as frequency domain and amplitude, and can perform filtering and noise reduction on the collected models.

[0057] (4) System Construction

[0058] Integrate parameter setting, data acquisition, waveform display, filtering and noise reduction, density solution and other functional modules. The detection program flowchart is as shown in the attached Fig. 9 shown.

[0059] The present invention is designed to first design a digital bandpass filter to filter the vibration feedback signal, and use the polynomial least squares method and the five-point cubic smoothing method to preprocess the signal; then, based on the principle of empirical mode decomposition (EMD), the vibration feedback signal is processed and analyzed to obtain the time-frequency joint distribution spectrum characteristics, providing data support for compaction state perception.

[0060] (1) Filter selection

[0061] Select FIR digital filter to perform digital filtering of vibration feedback signal, and reduce the order through reasonable parameter design, thus reducing the difficulty of filter implementation and hardware cost.

[0062] The essence of FIR filter design is to find a physically realizable system function H(z) so that its frequency response H(e jω ) approximates the ideal frequency response H required by the filter d (e jω ), the corresponding unit impulse response is h d(n), the basic process of FIR filter design is as follows Fig.10 As shown,

[0063] (2) Vibration signal analysis method

[0064] First, the empirical mode decomposition (EMD) method is used to decompose the given signal into the sum of several intrinsic mode functions (IMFs). These IMFs are components that meet certain conditions. Then, each IMF component is Hilbert transformed to obtain the Hilbert spectrum. Finally, the Hilbert spectrum of the original signal is obtained by summing up the Hilbert spectra of all IMF components, which is the energy distribution spectrum of the signal on the time-frequency plane, and then the marginal spectrum can be obtained.

[0065] The EMD method can decompose the chaotic vibration signal into multiple IMF components, so that different IMF components can be processed to extract local feature information, while removing noise and clutter in the original signal. The schematic diagram of the EMD decomposition and screening process is shown in the attached figure. Fig.11 shown.

[0066] The present invention is designed to establish a connection between the asphalt mixture properties k and c and the paving machine through on-site calibration, specifically, the density and vibration frequency (ω, ω d , t),

[0067] Before starting the paver, connect the online density detection instrument and arrange the various connection lines of the test instrument reasonably so as not to affect the normal construction of the construction personnel; tighten the thread of the serial port to prevent it from falling off during the test and affecting the test effect.

[0068] Before formally collecting data, the sensor needs to be installed in a reasonable position. The mechanically assembled paver screed is composed of multiple parts along the width of the road surface. In order to find a better position, the sensor was installed in the middle of the whole machine and the center of one side of the screed during the test. Finally, the better installation position was found by comparison.

[0069] After determining the location to install the acceleration sensor, turn on the acquisition system to collect the vibration signal of the ironing plate. At each vibration frequency ratio, collect the acceleration signal for about one minute after the paver is working stably, and save it as a data file for easy analysis. While collecting the signal, use a non-nuclear density meter to detect the density of the newly paved layer at this frequency. Keep the paver vibration frequency unchanged, change the vibration frequency of the ironing plate, and collect the acceleration signal through the acquisition system when the paver is working stably, and use a non-nuclear density meter to detect the density of the road surface. The frequency of the Vogele paver is in the form of percentage.

[0070] Finally, the signal is processed and the correlation between the paving density and the vibration acceleration signal is fitted to provide feedback for adjusting the angular velocity ω, ω of the vibrating mechanism and the vibration structure. d Provides data model, and can estimate paving density by setting vibration frequency. On-site calibration and online monitoring route map as attached Fig.12 shown.

[0071] When calibrating a non-nuclear density meter, the density should be measured by arranging measuring points with no less than 4 circles tangent to each other. Select 5 measuring points on a road surface with good flatness and no pollution. Each measurement needs to be rotated 90 degrees clockwise. The on-site calibration measuring point diagram is as attached. Fig.13 shown.

[0072] The present invention is designed that the vibrating ironing plate is composed of a box body, a vibrating beam, a vibrator and other parts. The side view of the ironing plate structure is shown in the attached figure. Fig.14 As shown, the vibrating mechanism is located at the front of the ironing plate and is one of the main components of the ironing plate. It adopts a double vibrating structure and is suspended on the eccentric shaft. The hydraulic motor drives the eccentric shaft to rotate through the transmission device, so that the vibrating beam performs reciprocating motion to perform initial compaction on the mixture. The vibration mechanism generates centrifugal force by the rotation of the eccentric block, and the centrifugal force is transmitted to the box through the bearing seat to make the ironing plate vibrate.

[0073] The present invention designs a control model acquisition system for online monitoring of density during asphalt mixture paving construction, which includes the following contents:

[0074] Paving system dynamics model building unit 10,

[0075] The acceleration signal detection system establishing unit 20,

[0076] Signal filtering and noise reduction establishment unit 30,

[0077] On-site calibration and online monitoring establishment unit 40.

[0078] The present invention designs a controller for online monitoring of the density of asphalt mixture paving construction process, which includes the following contents: a control model for online monitoring of the density of asphalt mixture paving construction process is stored in the controller,

[0079] The control model for online monitoring of the density of the asphalt mixture paving construction process is obtained according to the control model acquisition method for online monitoring of the density of the asphalt mixture paving construction process.

[0080] The present invention designs a control method for online monitoring of density during asphalt mixture paving construction, which includes the following contents:

[0081] A controller for online monitoring of the density of asphalt mixture paving construction process is used in the CPU for control. IV. Description of the drawings

[0082] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0083] Figure 1 This is a flow chart of the method for obtaining a control model for online monitoring of the density of asphalt mixture paving construction process.

[0084] Figure 2 This is a structural schematic diagram of a control model acquisition system for online monitoring of density during asphalt mixture paving construction according to the present invention.

[0085] Figure 3 is a periodic vibration shock wave,

[0086] Figure 4 is the frequency spectrum of periodic vibration shock wave,

[0087] Figure 5 It is a double vibrating compaction mechanism model.

[0088] Figure 6 is the vibration compaction model,

[0089] Figure 7 It is an online detection system for paving density.

[0090] Figure 8 The acceleration sensor installation position.

[0091] Fig. 9 To detect the program flowchart,

[0092] Fig.10 Design the basic process for FIR filter,

[0093] Fig.11 Schematic diagram of EMD decomposition and screening process.

[0094] Fig.12 For on-site calibration and online monitoring route map,

[0095] Fig.13 To calibrate the measuring point map on site,

[0096] Fig.14 This is the side view of the screed structure.

[0097] Fig.15 This is the vibration time domain diagram of the original signal collected in the experiment.

[0098] Fig.16 This is the time domain diagram of the vibration signal after filtering and preprocessing.

[0099] Fig.17 The comparison curve between the estimated density and the measured value and the error of the data are obtained. V. Specific implementation methods

[0100] According to the Examination Guidelines, terms such as “having”, “including” and “comprising” used in the present invention should be understood as not dispensing with the existence or addition of one or more other elements or combinations thereof.

[0101] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0102] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, it can be a mechanical connection, it can be an electrical connection, it can be a direct connection, it can be indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0103] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0104] The present invention is further described below in conjunction with examples. The following examples are intended to illustrate the present invention rather than to further limit the present invention.

[0105] A control model acquisition method for online monitoring of density during asphalt mixture paving construction, a first embodiment of the present invention, the steps are:

[0106] Step 100: Establish a paving system dynamics model.

[0107] Step 200: Establish an acceleration signal detection system.

[0108] Step 300: Establish signal filtering and noise reduction,

[0109] Step 400: Establish on-site calibration and online monitoring.

[0110] The following takes the online monitoring method for asphalt mixture paving density as an example to illustrate the specific implementation of the method.

[0111] In this embodiment, step 100 specifically includes the following contents:

[0112] (1) Vibration mechanism action model

[0113] Vibration has the characteristics of compaction and vibration compaction, but the vibration energy is weak, the energy of a single vibration decays quickly, and the vibration stroke is high and the impact interval is large. Therefore, multiple vibrations are regarded as intermittent periodic rectangular shock waves. The periodic vibration shock waves are shown in the attached figure. Figure 3 As shown,

[0114] The response function of the vibration compaction system is an attenuation signal (Formula (1-1)).

[0115]

[0116] α is the pulse width coefficient, which is 1 / 3T, the pulse height is E, and the vibration period is T.

[0117] The vibration excitation period is expressed using Fourier series:

[0118]

[0119] The spectrum of periodic vibration shock wave is shown in the attached figure. Figure 4 As shown,

[0120] The eccentric positions of the main and auxiliary vibrators differ by 180°. It can be considered that the vibrating hammers move in parallel without constraints in the vertical direction. The model can be simplified as shown in the attached figure. Figure 5 The double vibrating compaction mechanism model shown in the figure is

[0121] The dynamic equation of the vibrator is obtained by Fourier transform:

[0122]

[0123] Among them, f d1 and f d2 is the force exerted by the eccentric shaft on the main and auxiliary vibrators; k1, c1, k2, c2 are the stiffness coefficient and damping coefficient of the ply material under the main and auxiliary vibrators.

[0124] When the eccentric block contacts the pavement, the vibration force reaches the maximum value m1r1ω 2 d , and compact the pavement at the same time, the response acceleration, velocity and displacement of the vibrator can be obtained:

[0125]

[0126] According to the interaction principle between the vibrating mechanism and the ironing plate, combined with formula (1-3), the force R (t) exerted by the vibrator on the plate can be obtained as follows:

[0127]

[0128] (2) Vibration compaction mechanism action model

[0129] The vibration compaction model is shown in the attached Figure 6 ,

[0130] In order to better offset the influence of centrifugal force in the horizontal direction on the pavement paving quality, the symmetry line of the rotation center of the two eccentric shafts is made to pass vertically through the inertia center of the entire ironing plate; for the convenience of calculation and analysis, it is assumed that the resultant force exerted on the ironing plate by the material stiffness k and damping c at the bottom of the ironing plate passes through the center of mass of the ironing plate, and the moment of the force system composed of the exciting force and the supporting force on the center of mass is zero.

[0131] The dynamic differential equation of the screed is:

[0132]

[0133] k is the support stiffness coefficient of the medium; c is the resistance coefficient; x is the longitudinal displacement of the ironing board; Q(t) is the excitation generated by the rotation of the eccentric mass, Q(t) = 2m0rω 2 sin(ωt); r is the rotation radius; R(t) is the force exerted by the vibrator on the ironing plate.

[0134] Substituting equation (1-7) into equation (1-8), equation (1-9) constructs the acceleration of the screed plate and the angular velocity ω of the vibrating mechanism and the vibrating structure, ω d And the relationship between asphalt mixture properties k and c.

[0135]

[0136] Where:

[0137] M=m+2m0+m1+m2↓

[0138] C=c+c1+c2↓

[0139] K=k+k1+k2

[0140]

[0141] A5=2m0rω 2

[0143] In this embodiment, step 200 specifically includes the following contents:

[0144] From formula (1-9), it can be seen that the dynamic characteristics of the vibrating mechanism and the ironing plate can be directly measured by acceleration. Existing studies have shown that there is a certain correlation between the stiffness of the compressed material and the vibration acceleration. Therefore, the vibration dynamic parameters mainly based on the vibration acceleration can be analyzed to indirectly obtain the paving density. The density of the paving layer can be reflected by using the change in the acceleration of the ironing plate in the vertical direction.

[0145] The basic principle of the online paving density detection system is as follows: Figure 7 As shown,

[0146] (1) Signal measurement module

[0147] The sensor used should meet the construction requirements, be able to withstand temperatures of 110-120°C, and the acceleration measurement amplitude should not be less than 20m / s 2 It has the characteristics of high sensitivity and anti-interference. The installation position is on the ironing board below the middle part of the paver. The installation position of the acceleration sensor is as shown in the attached Figure 8 As shown,

[0148] (2) Signal acquisition module

[0149] The acquisition card should have an acceleration sensor drive unit, and integrate a DC isolation circuit and a charge amplifier for basic processing functions such as signal isolation and amplification. It should have a 16-bit ADC and a vibration signal acquisition frequency of 5kHz.

[0150] (3) Signal processing module

[0151] The signal processing module has the functions of time domain and frequency domain transformation, which can obtain signal characteristics such as frequency domain and amplitude, and can perform filtering and noise reduction on the collected models.

[0152] (4) System Construction

[0153] Integrate parameter setting, data acquisition, waveform display, filtering and noise reduction, density solution and other functional modules. The detection program flowchart is as shown in the attached Fig. 9 shown.

[0154] In this embodiment, step 300 specifically includes the following contents:

[0155] Firstly, a digital bandpass filter is designed to filter the vibration feedback signal, and the polynomial least squares method and five-point cubic smoothing method are used for signal preprocessing. Then, the vibration feedback signal is processed and analyzed based on the principle of empirical mode decomposition (EMD) to obtain the spectral characteristics of the joint distribution of time and frequency, providing data support for compaction state perception.

[0156] (1) Filter selection

[0157] Select FIR digital filter to perform digital filtering of vibration feedback signal, and reduce the order through reasonable parameter design, thus reducing the difficulty of filter implementation and hardware cost.

[0158] The essence of FIR filter design is to find a physically realizable system function H(z) so that its frequency response H(e jω ) approximates the ideal frequency response H required by the filter d (e jω ), the corresponding unit impulse response is h d (n), the basic process of FIR filter design is as follows Fig.10 As shown,

[0159] (2) Vibration signal analysis method

[0160] First, the empirical mode decomposition (EMD) method is used to decompose the given signal into the sum of several intrinsic mode functions (IMFs). These IMFs are components that meet certain conditions. Then, each IMF component is Hilbert transformed to obtain the Hilbert spectrum. Finally, the Hilbert spectrum of the original signal is obtained by summing up the Hilbert spectra of all IMF components, which is the energy distribution spectrum of the signal on the time-frequency plane, and then the marginal spectrum can be obtained.

[0161] The EMD method can decompose the chaotic vibration signal into multiple IMF components, so that different IMF components can be processed to extract local feature information, while removing noise and clutter in the original signal. The schematic diagram of the EMD decomposition and screening process is shown in the attached figure. Fig.11 shown.

[0162] In this embodiment, step 400 specifically includes the following contents:

[0163] Asphalt mixture properties k and c are linked to the paving machine through on-site calibration, specifically density and vibration frequency (ω, ω d , t),

[0164] Before starting the paver, connect the online density detection instrument and arrange the various connection lines of the test instrument reasonably so as not to affect the normal construction of the construction personnel; tighten the thread of the serial port to prevent it from falling off during the test and affecting the test effect.

[0165] Before formally collecting data, the sensor needs to be installed in a reasonable position. The mechanically assembled paver screed is composed of multiple parts along the width of the road surface. In order to find a better position, the sensor was installed in the middle of the whole machine and the center of one side of the screed during the test. Finally, the better installation position was found by comparison.

[0166] After determining the location to install the acceleration sensor, turn on the acquisition system to collect the vibration signal of the ironing plate. At each vibration frequency ratio, collect the acceleration signal for about one minute after the paver is working stably, and save it as a data file for easy analysis. While collecting the signal, use a non-nuclear density meter to detect the density of the newly paved layer at this frequency. Keep the paver vibration frequency unchanged, change the vibration frequency of the ironing plate, and collect the acceleration signal through the acquisition system when the paver is working stably, and use a non-nuclear density meter to detect the density of the road surface. The frequency of the Vogele paver is in the form of percentage.

[0167] Finally, the signal is processed and the correlation between the paving density and the vibration acceleration signal is fitted to provide feedback for adjusting the angular velocity ω, ω of the vibrating mechanism and the vibration structure. d Provides data model, and can estimate paving density by setting vibration frequency. On-site calibration and online monitoring route map as attached Fig.12 shown.

[0168] When calibrating a non-nuclear density meter, the density should be measured by arranging measuring points with no less than 4 circles tangent to each other. Select 5 measuring points on a road surface with good flatness and no pollution. Each measurement needs to be rotated 90 degrees clockwise. The on-site calibration measuring point diagram is as attached. Fig.13 shown.

[0169] In this embodiment, the vibrating ironing plate is composed of a box body, a vibrating beam, a vibrator and other parts. The side view of the ironing plate structure is shown in the attached figure. Fig.14 As shown, the vibrating mechanism is located at the front of the ironing plate and is one of the main components of the ironing plate. It adopts a double vibrating structure and is suspended on the eccentric shaft. The hydraulic motor drives the eccentric shaft to rotate through the transmission device, so that the vibrating beam performs reciprocating motion to perform initial compaction on the mixture. The vibration mechanism generates centrifugal force by the rotation of the eccentric block, and the centrifugal force is transmitted to the box through the bearing seat to make the ironing plate vibrate.

[0170] A control model acquisition system for online monitoring of density during asphalt mixture paving construction, including the following contents:

[0171] Paving system dynamics model building unit 10,

[0172] The acceleration signal detection system establishing unit 20,

[0173] Signal filtering and noise reduction establishment unit 30,

[0174] On-site calibration and online monitoring establishment unit 40.

[0175] A controller for online monitoring of the density of an asphalt mixture paving construction process includes the following contents: a control model for online monitoring of the density of an asphalt mixture paving construction process is stored in the controller.

[0176] In this embodiment, the control model for online monitoring of the density of the asphalt mixture paving construction process is obtained according to the above-mentioned control model acquisition method for online monitoring of the density of the asphalt mixture paving construction process.

[0177] Step 100: Establish a paving system dynamics model.

[0178] Step 200: Establish an acceleration signal detection system.

[0179] Step 300: Establish signal filtering and noise reduction,

[0180] Step 400: Establish on-site calibration and online monitoring.

[0181] A control method for online monitoring of density during asphalt mixture paving construction includes the following contents:

[0182] A controller for online monitoring of the density of asphalt mixture paving construction process is used in the CPU for control.

[0183] Case Study

[0184] The paver model used is The 2100-3L is used, the asphalt mixture for paving is ATB-25, the non-nuclear density meter model is PQ380, and the acquisition card model is MPS-060602.

[0185] (1) Signal noise reduction analysis

[0186] The vibration time domain diagram of the original signal collected in the experiment is as follows: Fig.15 shown.

[0187] In order to suppress the influence of noise and clutter on the effective vibration signal, FIR filtering is performed. In order to weaken the influence of clutter on the signal waveform, the trend term of the filtered vibration feedback signal is eliminated and smoothed based on the polynomial least squares method and the five-point cubic smoothing method. The final time domain diagram of the filtered and pre-processed vibration signal is shown in the attached figure. Fig.16 As shown,

[0188] In terms of composition, high-frequency noise components above 200Hz are basically filtered out. The main frequency components of the vibration feedback signal after filtering are relatively concentrated. The digital filtering and preprocessing methods effectively suppress the noise and clutter in the vibration feedback signal, significantly improve the signal-to-noise ratio, and improve the quality of the original vibration signal.

[0189] (2) Density fitting

[0190] The acceleration amplitude characteristics are extracted and combined with the density value measured by the non-nuclear density meter, the data are shown in Table 1, where the vibration frequency ratio is the ratio of the screed test vibration frequency to the maximum vibration frequency.

[0191] Table 1 Acceleration amplitudes at different vibration frequency ratios and density values ​​measured by non-nuclear density meter

[0192] Vibration frequency ratio / (%) 10 20 30 40 50 60 70 <![CDATA[Mean value of acceleration amplitude / (m / s 2 )]]> 1.12 1.57 1.79 2.07 2.44 2.75 3.10 Density / (%) 86.13 87.02 88.07 89.51 90.04 89.75 90.04

[0193] The relationship between the acceleration amplitude x and the paving density y obtained by fitting is:

[0194] y=-1.0006x 2 +6.4833x+79.866R 2 =0.9434

[0195] The fitted function expression is a quadratic polynomial with a correlation coefficient R 2 =0.9434, indicating that there is a good correlation between the two.

[0196] By setting the vibration frequency ratio, the paving density can be estimated, and the comparison curve between the estimated density value and the measured value and the error of the data can be obtained as shown in the attached figure. Fig.17 As shown,

[0197] Depend on Fig.16 It is found that the measured value of paving density is basically consistent with the estimated value of density, with little difference. This shows that the estimated value can better reflect the actual measured value, confirming that there is a good correlation between the acceleration amplitude and the paving density, and the fitted curve can be used as the mathematical basis of the density online detection system.

[0198] The error of the data is analyzed. The error of the two sets of measurements is as follows: Fig.16 The maximum error between the two does not exceed 0.6. The mean square error of the two sets of measured data relative to the estimated value is also very small, so the effect of using the designed online detection system to detect paving density is relatively good.

[0199] When verifying the present invention, we first proposed a technical feature of using the change signal of the acceleration in the vertical direction of the ironing plate to reflect the density of the paving layer, and obtained the first unexpected technical effect: the correlation between the acceleration amplitude of the ironing plate and the paving density was determined, and the density of the paving material could be well predicted, so the density online detection system had good reliability and feasibility, and obtained the second unexpected technical effect: the medium signal pickup was realized in the asphalt mixture paving stage, and the front signal pickup was realized for the online monitoring of the paving density, eliminating the later interference signal, and obtained the third unexpected technical effect: the installation accuracy of the sensor was improved, and the online monitoring accuracy was improved, and obtained the fourth unexpected technical effect: the sensor was installed on the ironing plate, and the service life of the sensor was extended.

[0200] The above embodiment is only one implementation form of the control model acquisition method and system, controller and control method for online monitoring of the density of asphalt mixture paving construction process provided by the present invention. Other variations of the scheme provided by the present invention, adding or reducing the components or steps therein, or applying the present invention to other technical fields close to the present invention, all fall within the scope of protection of the present invention.

Claims

1. A control model acquisition method for online monitoring of density during asphalt mixture paving construction. Its characteristics are: its steps are: Step 100: Establish a paving system dynamics model. Step 200: Establish an acceleration signal detection system. Step 300: Establish signal filtering and noise reduction, Step 400: Establish on-site calibration and online monitoring.

2. The method for obtaining a control model for online monitoring of density during asphalt mixture paving construction according to claim 1, Its characteristics are: (1) Vibration mechanism action model Vibration has the characteristics of compaction and vibration compaction, but the vibration energy is weak, the energy of a single vibration decays quickly, and the vibration stroke is high and the impact interval is large. Therefore, multiple vibrations are regarded as intermittent periodic rectangular shock waves. The periodic vibration shock wave is shown in Figure 3. The response function of the vibration compaction system is an attenuation signal (Formula (1-1)). α is the pulse width coefficient, which is 1 / 3T, the pulse height is E, and the vibration period is T. The vibration excitation period is expressed using Fourier series: The frequency spectrum of the periodic vibration shock wave is shown in Figure 4. The eccentric positions of the main and auxiliary vibrators differ by 180°. It can be considered that the vibrating hammers move in parallel without constraints in the vertical direction. The model can be simplified to the double-vibrating compaction mechanism model shown in Figure 5. The dynamic equation of the vibrator is obtained by Fourier transform: Among them, f d1 and f d2 k is the force of the eccentric shaft acting on the main and auxiliary vibrators; 1 、c 1 , k 2 、c 2 It is the stiffness coefficient and damping coefficient of the ply material under the main and auxiliary vibrators. When the eccentric block contacts the pavement, the vibration force reaches the maximum value m 1 r 1 ω 2 d , and compact the pavement at the same time, the response acceleration, velocity and displacement of the vibrator can be obtained: According to the interaction principle between the vibrating mechanism and the ironing plate, combined with formula (1-3), the force R (t) exerted by the vibrator on the plate can be obtained as follows: (2) Vibration compaction mechanism action model The vibration compaction model is shown in Figure 6. In order to better offset the influence of centrifugal force in the horizontal direction on the pavement paving quality, the symmetry line of the rotation center of the two eccentric shafts is made to pass vertically through the inertia center of the entire ironing plate; for the convenience of calculation and analysis, it is assumed that the resultant force exerted on the ironing plate by the material stiffness k and damping c at the bottom of the ironing plate passes through the center of mass of the ironing plate, and the moment of the force system composed of the exciting force and the supporting force on the center of mass is zero. The dynamic differential equation of the screed is: k is the support stiffness coefficient of the medium; c is the resistance coefficient; x is the longitudinal displacement of the ironing board; Q(t) is the excitation generated by the rotation of the eccentric mass, Q(t) = 2m 0 rω 2 sin(ωt); r is the rotation radius; R(t) is the force exerted by the vibrator on the ironing plate. Substituting equation (1-7) into equation (1-8), equation (1-9) constructs the acceleration of the screed plate and the angular velocity ω of the vibrating mechanism and the vibrating structure, ω d And the relationship between asphalt mixture properties k and c. Where: M=m+2m 0 +m 1 +m 2 ↓ C=c+c1+c2↓ K=k+k1+k2 A 5 =2m 0 rω 2 。 3. The control model acquisition method for online monitoring of density during asphalt mixture paving construction according to claim 1, Its characteristics are: From formula (1-9), it can be seen that the dynamic characteristics of the vibrating mechanism and the ironing plate can be directly measured by acceleration. Existing studies have shown that there is a certain correlation between the stiffness of the compressed material and the vibration acceleration. Therefore, the vibration dynamic parameters mainly based on the vibration acceleration can be analyzed to indirectly obtain the paving density. The density of the paving layer can be reflected by using the change in the acceleration of the ironing plate in the vertical direction. The basic principle of the online paving density detection system is shown in Figure 7. (1) Signal measurement module The sensor used should meet the construction requirements, be able to withstand temperatures of 110-120°C, and the acceleration measurement amplitude should not be less than 20m / s 2 It has the characteristics of high sensitivity and anti-interference. The installation position is on the ironing board below the middle part of the paver. The installation position of the acceleration sensor is shown in Figure 8. (2) Signal acquisition module The acquisition card should have an acceleration sensor drive unit, and integrate a DC isolation circuit and a charge amplifier for basic processing functions such as signal isolation and amplification. It should have a 16-bit ADC and a vibration signal acquisition frequency of 5kHz. (3) Signal processing module The signal processing module has the functions of time domain and frequency domain transformation, which can obtain signal characteristics such as frequency domain and amplitude, and can perform filtering and noise reduction on the collected models. (4) System Construction The detection program flowchart is shown in Figure 9, which integrates functional modules such as parameter setting, data acquisition, waveform display, filtering and noise reduction, and density solution.

4. The method for obtaining a control model for online monitoring of density during asphalt mixture paving construction according to claim 1, Its characteristics are: Firstly, a digital bandpass filter is designed to filter the vibration feedback signal, and the polynomial least squares method and five-point cubic smoothing method are used for signal preprocessing. Then, the vibration feedback signal is processed and analyzed based on the principle of empirical mode decomposition (EMD) to obtain the spectral characteristics of the joint distribution of time and frequency, providing data support for compaction state perception. (1) Filter selection Select FIR digital filter for digital filtering of vibration feedback signal, and reduce the order through reasonable parameter design, thus reducing the difficulty of filter implementation and hardware cost. The essence of FIR filter design is to find a physically realizable system function H(z) so that its frequency response H(e jω ) approximates the ideal frequency response H required by the filter d (e jω ), the corresponding unit impulse response is h d (n), the basic process of FIR filter design is shown in Figure 10, (2) Vibration signal analysis method First, the empirical mode decomposition (EMD) method is used to decompose the given signal into the sum of several intrinsic mode functions (IMFs). These IMFs are components that meet certain conditions. Then, each IMF component is Hilbert transformed to obtain the Hilbert spectrum. Finally, the Hilbert spectrum of the original signal is obtained by summing up the Hilbert spectra of all IMF components, which is the energy distribution spectrum of the signal on the time-frequency plane, and then the marginal spectrum can be obtained. The EMD method can decompose the messy vibration signal into multiple IMF components, so that different IMF components can be processed to extract local feature information, while removing noise and clutter in the original signal. The schematic diagram of the EMD decomposition and screening process is shown in Figure 11.

5. The control model acquisition method for online monitoring of density during asphalt mixture paving construction according to claim 2, Its characteristics are: asphalt The mixture properties k and c are linked to the paving machine through on-site calibration, specifically the density and vibration frequency (ω, ω d , t), Before starting the paver, connect the online density detection instrument and arrange the various connection lines of the test instrument reasonably so as not to affect the normal construction of the construction personnel; tighten the thread of the serial port to prevent it from falling off during the test and affecting the test effect. Before formally collecting data, the sensor needs to be installed in a reasonable position. The mechanically assembled paver screed is composed of multiple parts along the width of the road surface. In order to find a better position, the sensor was installed in the middle of the whole machine and the center of one side of the screed during the test. Finally, the better installation position was found by comparison. After determining the location to install the acceleration sensor, turn on the acquisition system to collect the vibration signal of the ironing plate. At each vibration frequency ratio, collect the acceleration signal for about one minute after the paver is working stably, and save it as a data file for easy analysis. While collecting the signal, use a non-nuclear density meter to detect the density of the newly paved layer at this frequency. Keep the paver vibration frequency unchanged, change the vibration frequency of the ironing plate, and collect the acceleration signal through the acquisition system when the paver is working stably, and use a non-nuclear density meter to detect the density of the road surface. The frequency of the Vogele paver is in the form of percentage. Finally, the signal is processed and the correlation between the paving density and the vibration acceleration signal is fitted to provide feedback for adjusting the angular velocity ω, ω of the vibrating mechanism and the vibration structure. d A data model is provided, and the paving density can be estimated by setting the vibration frequency. The on-site calibration and online monitoring route map is shown in Figure 12. When calibrating a non-nuclear density meter, the density should be measured by arranging measuring points with no less than 4 circles tangent to each other. Five measuring points should be selected on a smooth and pollution-free road surface. Each measurement needs to be rotated 90 degrees clockwise. The on-site calibration measuring point diagram is shown in Figure 13.

6. The control model acquisition method for online monitoring of density during asphalt mixture paving construction according to claim 2, Its characteristics are: The vibrating ironing plate is composed of a box body, a vibrating beam, a vibrator and other parts. The side view of the ironing plate structure is shown in Figure 14. The vibrating mechanism is located at the front of the ironing plate and is one of the main components of the ironing plate. It adopts a double vibrating structure and is suspended on the eccentric shaft. The hydraulic motor drives the eccentric shaft to rotate through the transmission device, so that the vibrating beam performs reciprocating motion to perform initial compaction on the mixture. The vibration mechanism generates centrifugal force by the rotation of the eccentric block, and the centrifugal force is transmitted to the box body through the bearing seat to make the ironing plate vibrate.

7. A control model acquisition system for online monitoring of density during asphalt mixture paving construction. Its characteristics are: Paving system dynamics model building unit 10, The acceleration signal detection system establishing unit 20, Signal filtering and noise reduction establishment unit 30, On-site calibration and online monitoring establishment unit 40.

8. A controller for online monitoring of density during asphalt mixture paving construction. Its characteristics are: The following contents are included: a control model for online monitoring of the density of asphalt mixture paving construction process is stored in the controller. The control model for online monitoring of the density of the asphalt mixture paving construction process is obtained according to the control model acquisition method for online monitoring of the density of the asphalt mixture paving construction process.

9. A control method for online monitoring of density during asphalt mixture paving construction. Its characteristics are: Contains the following content: A controller for online monitoring of the density of asphalt mixture paving construction process is used in the CPU for control.

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