CN113225047A - TVLP-MF-based dynamic checkweigher rapid filtering method and system - Google Patents
TVLP-MF-based dynamic checkweigher rapid filtering method and system Download PDFInfo
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Abstract
The invention discloses a TVLP-MF (transient voltage waveform-frequency) -based quick filtering method and system for a dynamic checkweigher, wherein the method comprises the steps of filtering a sampling signal of a weighing sensor through a time-varying low-pass filter to eliminate interference; filtering the filtered output signal through a morphological filter to improve the response speed; and estimating based on the output of the morphological filter to obtain the weight value of the measured object. The dynamic checkweigher aims to eliminate vibration interference generated by a mechanical structure of the dynamic checkweigher and an external environment, improves the running efficiency and the weighing accuracy of the dynamic checkweigher, has the advantages of simple operation, high calculation speed, good robustness and the like, and effectively improves the measuring efficiency and the weighing result accuracy of the dynamic checkweigher.
Description
Technical Field
The invention relates to a dynamic weighing technology of a checkweigher, in particular to a TVLP-MF-based rapid filtering method and system of a dynamic checkweigher.
Background
Checkweighers are mass-sorting automated scales that subdivide prepackaged discrete loads of different masses into two or more classes based on their differential values of mass from a nominal set point. Along with the rapid development of modern industry and agriculture, the demand of the checkweigher on the production line is increasing day by day, and the checkweigher can rapidly and accurately estimate the weight of a measured object and perform sorting under the states that the measured object is not static, the production line is not stopped and the like, thereby improving the efficiency of the production line and ensuring the product quality. However, in the dynamic weighing process, the dynamic weighing duration is short, and the influence of factors such as mechanical vibration, electromagnetic interference and external environment noise exists, and the weighing signal is difficult to reach a steady state, so that the sorting efficiency and the weighing accuracy of the checkweigher are seriously influenced.
In order to solve various interference problems in dynamic weighing signals, various solutions have been proposed by domestic and foreign scholars. In the aspect of vehicle dynamic weighing filtering, an authorized chinese patent ZL 200710018456.0 discloses an "adaptive filtering method for vehicle dynamic weighing scale weighing signal", but the method is difficult to implement in an embedded manner in a practical application process by means of an empirical mode decomposition method. In signal spectrum analysis for a checkweigher, interference is mainly distributed in a high-frequency range relative to a weighing signal, so that a low-pass filter is an effective signal processing method. The influence of various interferences can be effectively inhibited by setting a proper cut-off frequency, and the accuracy of the weighing result of the dynamic checkweigher is improved. However, the conventional linear low-pass filter has a contradiction between performance and response speed, and the lower the cut-off frequency, the longer the filter response time. Therefore, under the condition of high-speed operation of the checkweigher, the response time of the filter is longer than the loading time of the measured object, and the measurement accuracy is reduced.
Piskorowski J et al, in 2008, proposed a Time-variable Low-Pass Filter (TVLP) in the document "Dynamic compensation of load cell response" and applied to a Dynamic checkweigher, to make up for the disadvantage of the conventional linear Low-Pass Filter that the response Time is too long in the transition signal processing. When the signal jumps, the bandwidth of the filter is adjusted to be larger in the jump time of the input signal, so that the edge signal can respond quickly, and the bandwidth is gradually adjusted back to an optimal value after the jump is finished, so that the interference in the signal is effectively filtered. Although the time-varying low-pass filter has both the filtering effect and the response speed, the time-varying low-pass filter still has a difficult satisfactory result in the practical application of the checkweigher under the high-speed working condition (the speed is more than 100 m/min).
Disclosure of Invention
The technical problems to be solved by the invention are as follows: aiming at the problems in the prior art, the invention provides a TVLP-MF-based quick filtering method and system for a dynamic checkweigher, aims to eliminate vibration interference generated by the mechanical structure of the dynamic checkweigher and the external environment, improves the operating efficiency and the weighing accuracy of the dynamic checkweigher, has the advantages of simple operation, high calculation speed, good robustness and the like, and effectively improves the measuring efficiency and the weighing result accuracy of the dynamic checkweigher.
In order to solve the technical problems, the invention adopts the technical scheme that:
a TVLP-MF-based dynamic checkweigher fast filtering method comprises the following steps:
1) filtering a sampling signal of the weighing sensor by a time-varying low-pass filter to eliminate interference;
2) filtering the filtered output signal through a morphological filter to improve the response speed;
3) and estimating based on the output of the morphological filter to obtain the weight value of the measured object.
Optionally, the processing of the sampling signal by the time-varying low-pass filter in step 1) includes: the bandwidth is adjusted to be large when the signal jumps, so that the edge signal can respond quickly; after the signal jump is finished, the bandwidth is gradually adjusted back to the optimal value, so that the interference in the sampling signal is effectively filtered.
Optionally, the time-varying low-pass filter in step 1) is a cascade of a plurality of first-order infinite impulse response filters, wherein a functional expression of the first-order infinite impulse response filter is:
y(n)=β(j)(x(n)+x(n-1)) - α(j)y(n-1)
in the above formula, the first and second carbon atoms are,nin the form of a discrete time variable,y(n) The output of the first-order infinite impulse response filter at the current moment,y(n-1) the output at a time instant above the first order infinite impulse response filter,x(n) Is the input of the first-order infinite impulse response filter at the current moment,x(n-1) for the input at a time instant on the first order infinite impulse response filter,β(j) Andα(j) As a time varying parameter.
Optionally, a time-varying parameterβ(j) Andα(j) The formula of the calculation function is:
in the above formula, the first and second carbon atoms are,f c (j) In order to cut-off the frequency of the filter,j=1,…,Nto loadThe number of the segment is given by the segment number,Nfor the number of signal samples of the loading section,j=1 corresponds to the moment when the object to be measured is about to enter the weighing belt,j=Ncorresponding to the moment when the object to be measured is about to leave the weighing belt,cand an intermediate variable, delta represents the signal digitization sampling interval,kthe number of cascades of the first-order infinite impulse response filter,f 0in order to be the initial cut-off frequency,f ∞in order to terminate the cut-off frequency,λis a constant coefficient of less than 0.1,εfor controlling the decay rate of the cut-off frequency.
Optionally, the filtering, by the morphological filter, of the output signal filtered by the time-varying low-pass filter in step 2) means that a weighted morphological filtering operation is adopted by the improved morphological filter IMF, and the output signal of the improved morphological filter IMF is obtainedy wcooc (n) The functional expression of (a) is:
in the above formula, the first and second carbon atoms are,nare the serial numbers of the discrete times and are,win order to be the weight coefficient,y co (n) For time-lapse low-pass filter-filtered output signalsy(n) As a result of the on-off operation of (c),y oc (n) For time-lapse low-pass filter-filtered output signalsy(n) And has the following operation results:
in the above formula, the first and second carbon atoms are,
representing the output signal after filtering by a time-lapse low-pass filtery(n) Firstly, performing morphological closing operation, and then performing morphological opening operation on an operation result of the morphological closing operation;
representing the output signal after filtering by a time-lapse low-pass filtery(n) Firstly, performing morphology opening operation, and then performing morphology closing operation on a morphology opening operation result; wherein
And
respectively representing the operation of morphological opening operation and morphological closing operation,yis the output signal filtered by the time-varying low-pass filter,gin order to operate the structural elements in a morphological way,nare discrete time series numbers.
Optionally, the computation function expression of the morphological open operation and the morphological close operation is:
in the above formula, the first and second carbon atoms are,
and
respectively representing morphological open and close operations,
representing the output signal after filtering by a time-lapse low-pass filtery(n) The operation result of the morphological opening operation of (2),
representing the output signal after filtering by a time-lapse low-pass filtery(n) The result of the morphological closing operation of (2),
and
the symbols represent the morphological dilation and erosion operations respectively,yis the output signal filtered by the time-varying low-pass filter,gin order to operate the structural elements in a morphological way,nis a discrete time sequence number; the computational function expression of the morphological dilation and erosion operation is as follows:
in the above formula, the first and second carbon atoms are,
for time-lapse low-pass filter-filtered output signalsy(n) As a result of the morphological dilation operation of (2),
for time-lapse low-pass filter-filtered output signalsy(n) The result of the morphological etching operation of (2),y(n-m) Representing the output signal after filtering by a time-varying low-pass filtery(n) Front sidemThe value corresponding to the time of day is,y(n+m) Representing the output signal after filtering by a time-varying low-pass filtery(n) HysteresismThe value corresponding to the time of day is,g(m) Is length ofMZero-valued linear structural elements of (1).
Optionally, the function expression estimated based on the output of the morphological filter in step 3) is:
in the above formula, the first and second carbon atoms are,Mis a weight value of the measured object,M cal in order to correct the weight of the weight used,Dthe filter output value of the improved morphological filter IMF corresponding to the object to be measured when the object to be measured begins to leave the weighing belt,D 0is the output value of the filtering in the idle state,D calis the filter output value of the correction weight.
In addition, the invention also provides a TVLP-MF-based dynamic checkweigher fast filtering system which comprises a microprocessor and a memory which are connected with each other, wherein the microprocessor or an upper computer connected with the microprocessor is programmed or configured to execute the steps of the TVLP-MF-based dynamic checkweigher fast filtering method.
In addition, the invention also provides a dynamic checkweigher device based on TVLP-IMF, which comprises a control unit, a feeding belt, a weighing belt and a sorting belt which are sequentially arranged along a straight line, wherein a weighing sensor is arranged on the lower side of the weighing belt, the control unit comprises a microprocessor and a memory which are mutually connected, a front photoelectric sensor is arranged above the feeding side of the weighing belt, a rear photoelectric sensor is arranged above the discharging side of the weighing belt, the output ends of the front photoelectric sensor, the rear photoelectric sensor and the weighing sensor are respectively connected with the microprocessor, and the microprocessor or an upper computer connected with the microprocessor is programmed or configured to execute the steps of the rapid filtering method of the dynamic checkweigher based on TVLP-MF.
Furthermore, the present invention also provides a computer readable storage medium having stored therein a computer program programmed or configured to execute the TVLP-MF based dynamic checkweigher fast filtering method.
Compared with the prior art, the invention has the following advantages:
1. the invention adopts the digital time-varying low-pass filter as the primary filtering, can effectively eliminate the main mechanical vibration interference and inhibit the phase distortion of the weighing signal in the filtering process.
2. The invention adopts the second-stage filtering of the filtered output signal through the morphological filter to improve the response speed, and further processes the weighing signal, thereby accelerating the dynamic weighing response and improving the weighing accuracy.
3. The invention adopts the combination of the first-stage filtering and the second-stage filtering, not only eliminates various interferences, but also inhibits the distortion of signals in the dynamic weighing signal processing, thereby obtaining a better dynamic weighing effect than the prior art and having great improvement on the performance of the dynamic checkweigher.
4. According to the invention, the weight of the measured object is estimated according to the signals after the two-stage filtering, and the final estimated value is obtained and output, so that the high-speed high-precision accurate weighing and sorting of the dynamic checkweigher are realized.
5. The method has the advantages of simple operation, high calculation speed and easy embedded real-time implementation.
Drawings
Fig. 1 is a schematic diagram of a basic flow of the method of this embodiment.
Fig. 2 is a schematic diagram of the weighing signal and the photoelectric signal mark of the dynamic checkweigher in this embodiment.
Fig. 3 is a schematic block diagram of a signal acquisition circuit of the load cell in the present embodiment.
Fig. 4 is a diagram of the signal loading of the dynamic checkweigher 201.7g to the measured object in this embodiment.
Fig. 5 is a diagram of the digital time-varying low-pass filtering result of the loading signal of the dynamic checkweigher 201.7g in this embodiment.
Fig. 6 is a comparison graph of the TVLP filtering and TVLP-IMF filtering results of the loading signal of the dynamic checkweigher 201.7g in this embodiment.
Fig. 7 is a table of national standard parameters of the automatic sorting weighing apparatus.
Fig. 8 is a graph illustrating the TVLP-IMF filtering performance, TVLP filtering performance and national standard requirements in this embodiment.
Detailed Description
The TVLP-MF based dynamic checkweigher fast filtering method and system of the present invention will be described in detail with reference to the accompanying drawings and embodiments, it should be understood that the present embodiment is only for explaining and illustrating the present invention, but not limited thereto.
As shown in fig. 1, the dynamic checkweigher fast filtering method based on TVLP-MF in this embodiment includes:
1) filtering a sampling signal of the weighing sensor by a Time-variable Low-Pass (TVLP) filter to eliminate interference;
2) filtering the filtered output signal by a Morphological Filter (abbreviated as MF) to improve the response speed;
3) and estimating based on the output of the morphological filter to obtain the weight value of the measured object.
In the embodiment, the output signal of the symmetrical retransmission sensor is subjected to discretization sampling at the sampling frequency of 2 kHz to obtain the discrete signal of the loading section of the measured objectx(n) Discrete signalx(n) Can be expressed asx(1), x(2),…, x(N) Whereinx(1)～x(N) 1 st to E, respectively, loading segmentsNThe number of the sampled values is determined,Nfor number of signal samples in loading section, the 1 st sample value corresponds to t1Time, i.e. the time when the object to be measured starts to enter the weighing belt (pre-triggering photosensor), secondNEach sample value corresponds to t3The time, i.e. the time when the measured object starts to leave the weighing belt (the photoelectric sensor after triggering), is shown in fig. 2, where a is the time period of the photoelectric sensor before triggering, b is the time period of the photoelectric sensor after triggering, c is the original signal, d is the ideal signal, t is the ideal signal2The time being the end of the time period a, t4The time is the end time of the time period b. Referring to fig. 3, the signal acquisition circuit for the output signal of the weighing sensor in this embodiment includes an amplifier, a hardware low-pass filter, and an analog-to-digital converter ADC, and the signal acquisition circuit performs amplification, low-pass filtering, and analog-to-digital conversion, and then inputs the signal to the single chip microcomputer STM32 to execute the processing steps of the TVLP-MF-based dynamic checkweigher fast filtering method in this embodiment, and then uploads the weight value of the object to be measured to the PC through serial port communication. In this embodiment, discrete signals are usedx(n) As input to the time-varying low-pass filter, an output signal is obtained by the time-varying low-pass filter asy(n)。
In the embodiment, the output signals of sensors of the carton packaged objects with the system running speeds of 30 m/min, 60 m/min, 90 m/min and 120 m/min and the static weights of 52.3 g, 175.4 g, 201.7g and 329.5 g are respectively collected at the sampling rate of 2 kHz, and each object is repeatedly loaded for 20 times at different speeds to obtain 320 groups of load signals with various weights under different working conditions. Taking data acquired by single loading of 201.7g of a measured object at four operating speeds as an example, as shown in fig. 4(a) - (d), photoelectric marking signals are loading intervals for marking the object through the front and rear photoelectric sensors.
In this embodiment, the processing of the sampling signal by the time-varying low-pass filter in step 1) includes: the bandwidth is adjusted to be large when the signal jumps, so that the edge signal can respond quickly; after the signal jump is finished, the bandwidth is gradually adjusted back to the optimal value, so that the interference in the sampling signal is effectively filtered.
In this embodiment, the time-varying low-pass filter in step 1) is a cascade of a plurality of first-order infinite impulse response filters, where a functional expression of the first-order infinite impulse response filter is:
y(n)=β(j)(x(n)+x(n-1)) - α(j)y(n-1)
in the above formula, the first and second carbon atoms are,nin the form of a discrete time variable,y(n) The output of the first-order infinite impulse response filter at the current moment,y(n-1) the output at a time instant above the first order infinite impulse response filter,x(n) Is the input of the first-order infinite impulse response filter at the current moment,x(n-1) for the input at a time instant on the first order infinite impulse response filter,β(j) Andα(j) As a time varying parameter.
In this embodiment, the time-varying parameterβ(j) Andα(j) The formula of the calculation function is:
in the above formula, the first and second carbon atoms are,f c (j) In order to cut-off the frequency of the filter,j=1,…,Nin order to load the segment labels,Nfor the number of signal samples of the loading section,j=1 corresponds to the moment when the object to be measured is about to enter the weighing belt,j=Ncorresponding to the moment when the object to be measured is about to leave the weighing belt,cand an intermediate variable, delta represents the signal digitization sampling interval,kthe number of cascades of the first-order infinite impulse response filter,f 0in order to be the initial cut-off frequency,f ∞to terminate the cut-off frequency (f ∞< f 0），λIs a constant coefficient of less than 0.1,εfor controlling the decay rate of the cut-off frequency. In the present embodiment, the constant coefficientλ=0.01, number of cascaded filtersk=3, finally obtaining an output signal as a filtered output signaly(n)。
The filtering effect of the time-varying low-pass filter depends on the initial cut-off frequencyf 0Terminating the cut-off frequencyf ∞And attenuation ratio of cutoff frequencyεAnd the like. According to the optimization design of the grid algorithm, the optimal parameters in the embodiment are as follows:
the optimal parameters when the conveying speed is 30 m/min are as follows:f 0=24Hz、f ∞=0.05Hz、ε=1.08；
the optimal parameters when the conveying speed is 60 m/min are as follows:f 0=26Hz、f ∞=0.05Hz、ε=1.08；
the optimal parameters when the conveying speed is 90 m/min are as follows:f 0=36Hz、f ∞=0.05Hz、ε=1.08；
the optimal parameters when the conveying speed is 120 m/min are as follows:f 0=36Hz、f ∞=0.05Hz、ε=0.8；
in the idle phase, a fixed cut-off frequency of 2Hz is set, when the first photoelectric signal is triggered, i.e. when the first photoelectric signal is triggeredt 1At the moment of the second photoelectric trigger, i.e.t 3At the moment, the data processing is started through the time-varying low-pass filter, wherein for example, 201.7g of data acquired by single loading of the measured object at four operating speeds are taken as the data, as shown in subgraphs (a) to (d) in fig. 5. In each of the graphs (a) to (d) in fig. 5, an original signal and a photoelectric marker signal are added for comparison, in addition to the signal (time-varying low-pass filter) result obtained in the present embodiment.
In this embodiment, the filtered output signaly(n) Obtaining an output signal of the improved morphology filter IMF as an input of the improved morphology filter IMFy wcooc (n). A Morphological Filter (MF), as a nonlinear Filter, is established based on integration geometry and stochastic set theory and is different from a signal processing method based on time domain and frequency domain. The MF only depends on the local shape characteristics of the signal to be processed when signal processing is carried out, a complex signal is decomposed into parts with physical significance through mathematical form transformation, the parts are stripped from the background, and the main shape characteristics of the signal are kept. Based on the theory, the invention adopts a Morphological Filter (MF) to carry out secondary filtering, and provides an Improved Method (IMF) of a weighting operation operator, through selecting a zero-value linear structural element, optimizing the length and weight coefficient of the structural element, further processing a weighing signal and accelerating dynamic weighing response, specifically, in the step 2), filtering an output signal filtered by the time-lapse low-pass Filter through the Morphological Filter refers to adopting weighting Morphological filtering operation through improving the Morphological Filter IMF (improved Morphological Filter), and improving the output signal of the Morphological Filter IMFy wcooc (n) The functional expression of (a) is:
in the above formula, the first and second carbon atoms are,nare the serial numbers of the discrete times and are,win order to be the weight coefficient,y co (n) For time-lapse low-pass filter-filtered output signalsy(n) As a result of the on-off operation of (c),y oc (n) For time-lapse low-pass filter-filtered output signalsy(n) And has the following operation results:
in the above formula, the first and second carbon atoms are,
representing the output signal after filtering by a time-lapse low-pass filtery(n) Firstly, performing morphological closing operation, and then performing morphological opening operation on an operation result of the morphological closing operation;
representing the output signal after filtering by a time-lapse low-pass filtery(n) Firstly, performing morphology opening operation, and then performing morphology closing operation on a morphology opening operation result; wherein
And
respectively representing the operation of morphological opening operation and morphological closing operation,yis the output signal filtered by the time-varying low-pass filter,gin order to operate the structural elements in a morphological way,nare discrete time series numbers.
In this embodiment, the calculation function expressions of the morphology open operation and the morphology close operation are:
in the above formula, the first and second carbon atoms are,
and
respectively representing morphological open and close operations,
representing the output signal after filtering by a time-lapse low-pass filtery(n) The operation result of the morphological opening operation of (2),
representing the output signal after filtering by a time-lapse low-pass filtery(n) The result of the morphological closing operation of (2),
and
the symbols represent the morphological dilation and erosion operations respectively,yis the output signal filtered by the time-varying low-pass filter,gin order to operate the structural elements in a morphological way,nis a discrete time sequence number; the computational function expression of the morphological dilation and erosion operation is as follows:
in the above formula, the first and second carbon atoms are,
for time-lapse low-pass filter-filtered output signalsy(n) As a result of the morphological dilation operation of (2),
for time-lapse low-pass filter-filtered output signalsy(n) The result of the morphological etching operation of (2),y(n-m) Representing the output signal after filtering by a time-varying low-pass filtery(n) Front sidemThe value corresponding to the time of day is,y(n+m) Representing the output signal after filtering by a time-varying low-pass filtery(n) HysteresismThe value corresponding to the time of day is,g(m) Is length ofMZero-valued linear structural elements of (1).
In this embodiment, the filtered output signaly(n) Is defined asD[y]={1,2,…,L}，LFor the filtered output signaly(n) Length of (d); zero value linear structural elementg(m) Can be expressed asg(m) Linear structural element of value zero (= 0,0, …,0}, and linear structural element of value zerog(m) Is defined asD[g]={1,2,…,M}，MIs the length of a linear structural element of zero value and has L>And M. Finally, the filtered output signal is filteredy(n) Obtaining an output signal of the improved morphology filter IMF as an input of the improved morphology filter IMFy wcooc (n)。
The performance of the improved morphological filter IMF depends mainly on the chosen zero-valued linear structuring elementg(m) Length of (2)MAnd weight coefficientw. In this embodiment, the zero-valued linear structural element is obtained by the optimization designg(m) Length of (2)M605, 425, 355, 355 respectively according to different speeds, and weight coefficientswRespectively 0.7, 0.85, 0.9 and 0.9. Using designed zero-value linear structural elementsg(m) And performing secondary filtering processing on the input signal by adopting an improved morphological operation operator, wherein experimental results are shown as subgraphs (a) to (d) in fig. 6, and a loading segment local signal diagram is amplified. In the diagrams (a) to (d) in fig. 6, signals (time-varying low-pass) obtained in this example are excluded&Improved morphology) results, the original signal, the signal processed by the time-varying low-pass filter, the photo-electric mark signal were added as a comparison.
In this embodiment, the function expression estimated based on the output of the morphological filter in step 3) is:
in the above formula, the first and second carbon atoms are,Mis a weight value of the measured object,M cal in order to correct the weight of the weight used,Dthe filter output value of the improved morphological filter IMF corresponding to the object to be measured when the object to be measured begins to leave the weighing belt,D 0is the output value of the filtering in the idle state,D calis the filter output value of the correction weight. Wherein the object to be measured starts to leave the weighing belt as shown in fig. 2t 3At the moment, the filter output value corresponding to the IMF of the improved morphology filter can be expressed asy wcooc (N). In the present embodiment, the first and second electrodes are,D 0=2715400 represents the corresponding sampled value at no load,D caland =3089100 represents the sampling value corresponding to the calibration weight.
And (3) analyzing an experimental result: according to XIII level accuracy requirement provided in the national standard GB/T27739-2011 automatic sorting weighing apparatus as a criterion, the national standard requirement of average error and standard deviation under different qualities is shown in FIG. 7, wherein the system average indication value, the average error and the standard deviation calculation formula are respectively as follows:
in the above formula, the first and second carbon atoms are,
the average indication value is represented by a value,x i representing the estimated weight value of the measured object,nrepresenting the number of samples of the corresponding mass in the test set,μthe average error is represented by the average error,σthe standard deviation is indicated. The performance Λ of the evaluation algorithm can be evaluated by:
according to the above formula, the filtering performance of the measured object by the method (time-varying low-pass & improved morphology) of the present embodiment and the comparison between the filtering performance of the time-varying low-pass filtering and the national standard requirements can be calculated and obtained as shown in subgraphs (a) to (d) in fig. 8. As can be seen from sub-diagrams (a) - (d) in fig. 8, the filtering performance of the dynamic checkweigher fast filtering method based on TVLP-MF in this embodiment is better than that of the time-varying low-pass filtering (the smaller the performance Λ is, the better the performance is).
In summary, compared with the prior art, the method of the present embodiment has the following advantages: 1. in the embodiment, a digital time-varying low-pass filter is used as primary filtering, and the parameters of the filter are optimally designed, so that the main mechanical vibration interference is effectively eliminated, and the phase distortion of a weighing signal in the filtering process is inhibited. 2. In the embodiment, a morphological filter is used as secondary filtering, an improved method of a weighting operation operator is provided, the length and weight coefficient of a structural element are optimally designed by selecting a zero-value linear structural element, a weighing signal is further processed, dynamic weighing response is accelerated, weighing accuracy is improved 3, the weight of a measured object is estimated according to signals after the two-stage filtering, a final estimated value is obtained and output, and high-speed, high-precision, accurate weighing and sorting of the dynamic checkweigher are realized. The TVLP-MF based dynamic checkweigher fast filtering method provided in this embodiment combines advantages of a digital time-varying low-pass filter and a morphological filtering method, particularly improves disadvantages of a conventional morphological method, and provides an improved weighted morphological operation operator, which not only eliminates various interferences but also suppresses distortion of signals in dynamic weighing signal processing, thereby obtaining a dynamic weighing effect better than that of the prior art. The embodiment has the advantages of simple operation, high calculation speed, good robustness and the like, and effectively improves the measurement efficiency and the weighing result accuracy of the dynamic checkweigher.
In addition, the present embodiment further provides a TVLP-MF based dynamic checkweigher fast filtering system, which includes a microprocessor and a memory connected to each other, where the microprocessor or an upper computer connected to the microprocessor is programmed or configured to execute the steps of the aforementioned TVLP-MF based dynamic checkweigher fast filtering method.
In addition, the present embodiment further provides a dynamic checkweigher device based on TVLP-IMF, including a control unit, a feeding belt, a weighing belt and a sorting belt sequentially arranged along a straight line, a weighing sensor is disposed on the lower side of the weighing belt, the control unit includes a microprocessor and a memory connected to each other, a front photoelectric sensor is disposed above the feeding side of the weighing belt, a rear photoelectric sensor is disposed above the discharging side of the weighing belt, output ends of the front photoelectric sensor, the rear photoelectric sensor and the weighing sensor are respectively connected to the microprocessor, and an upper computer connected to the microprocessor or the microprocessor is programmed or configured to execute the steps of the aforementioned fast filtering method for the dynamic checkweigher based on TVLP-MF. In this embodiment, the control unit is embedded for the core based on STM32 to STM32 is the core processor, carries on the signal processing circuit shown in FIG. 3, cuts to the hardware low pass filter circuit that the frequency is 50Hz, ADS1255 signal analog-to-digital conversion circuit and with host computer communication circuit, with 2 kHz's sampling frequency, the discretization sampling is carried out to the symmetry retransmission sensor output signal, obtains the discretization signalx(n)。
Furthermore, the present embodiment also provides a computer readable storage medium, in which a computer program programmed or configured to execute the aforementioned TVLP-MF based dynamic checkweigher fast filtering method is stored.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-readable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein. The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks. These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks. These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.
Claims (10)
1. A TVLP-MF-based dynamic checkweigher fast filtering method is characterized by comprising the following steps:
1) filtering a sampling signal of the weighing sensor by a time-varying low-pass filter to eliminate interference;
2) filtering the filtered output signal through a morphological filter to improve the response speed;
3) and estimating based on the output of the morphological filter to obtain the weight value of the measured object.
2. The TVLP-MF based dynamic checkweigher fast filtering method of claim 1, wherein the processing of the sampled signal by the time-varying low-pass filter in step 1) comprises: the bandwidth is adjusted to be large when the signal jumps, so that the edge signal can respond quickly; after the signal jump is finished, the bandwidth is gradually adjusted back to the optimal value, so that the interference in the sampling signal is effectively filtered.
3. The TVLP-MF based dynamic checkweigher fast filtering method of claim 2, wherein the time-varying low-pass filter in step 1) is a cascade of a plurality of first-order infinite impulse response filters, wherein the function expression of the first-order infinite impulse response filters is:
y(n)=β(j)(x(n)+x(n-1)) - α(j)y(n-1)
in the above formula, the first and second carbon atoms are,nin the form of a discrete time variable,y(n) The output of the first-order infinite impulse response filter at the current moment,y(n-1) the output at a time instant above the first order infinite impulse response filter,x(n) Is the input of the first-order infinite impulse response filter at the current moment,x(n-1) for the input at a time instant on the first order infinite impulse response filter,β(j) Andα(j) As a time varying parameter.
4. The TVLP-MF based dynamic checkweigher fast filtering method as claimed in claim 3, wherein time-varying parametersβ(j) Andα(j) The formula of the calculation function is:
in the above formula, the first and second carbon atoms are,f c (j) In order to cut-off the frequency of the filter,j=1,…,Nin order to load the segment labels,Nfor the number of signal samples of the loading section,j=1 corresponds to the moment when the object to be measured is about to enter the weighing belt,j=Ncorresponding to the moment when the object to be measured is about to leave the weighing belt,cand an intermediate variable, delta represents the signal digitization sampling interval,kthe number of cascades of the first-order infinite impulse response filter,f 0in order to be the initial cut-off frequency,f ∞in order to terminate the cut-off frequency,λis a constant coefficient of less than 0.1,εfor controlling the decay rate of the cut-off frequency.
5. The TVLP-MF based dynamic checkweigher fast filtering method as claimed in claim 1, wherein the filtering of the time-varying low-pass filter filtered output signal by the morphological filter in step 2) means that the weighted morphological filtering operation is adopted by the modified morphological filter IMF, and the output signal of the modified morphological filter IMFy wcooc (n) The functional expression of (a) is:
in the above formula, the first and second carbon atoms are,nare the serial numbers of the discrete times and are,win order to be the weight coefficient,y co (n) For time-lapse low-pass filter-filtered output signalsy(n) As a result of the on-off operation of (c),y oc (n) For time-lapse low-pass filter-filtered output signalsy(n) And has the following operation results:
in the above formula, the first and second carbon atoms are,
representing the output signal after filtering by a time-lapse low-pass filtery(n) Firstly, performing morphological closing operation, and then performing morphological opening operation on an operation result of the morphological closing operation;
representing the output signal after filtering by a time-lapse low-pass filtery(n) Firstly, performing morphology opening operation, and then performing morphology closing operation on a morphology opening operation result; wherein
And
respectively representing the operation of morphological opening operation and morphological closing operation,yis the output signal filtered by the time-varying low-pass filter,gin order to operate the structural elements in a morphological way,nare discrete time series numbers.
6. The TVLP-MF based dynamic checkweigher fast filtering method as claimed in claim 5, wherein the computational function expression of the morphology on operation and morphology off operation is:
in the above formula, the first and second carbon atoms are,
and
respectively representing morphological open and close operations,
representing the output signal after filtering by a time-lapse low-pass filtery(n) The operation result of the morphological opening operation of (2),
representing the output signal after filtering by a time-lapse low-pass filtery(n) The result of the morphological closing operation of (2),
and
the symbols represent the morphological dilation and erosion operations respectively,yis the output signal filtered by the time-varying low-pass filter,gin order to operate the structural elements in a morphological way,nis a discrete time sequence number; the computational function expression of the morphological dilation and erosion operation is as follows:
in the above formula, the first and second carbon atoms are,
for time-lapse low-pass filter-filtered output signalsy(n) As a result of the morphological dilation operation of (2),
for time-lapse low-pass filter-filtered output signalsy(n) The result of the morphological etching operation of (2),y(n-m) Representing the output signal after filtering by a time-varying low-pass filtery(n) Front sidemThe value corresponding to the time of day is,y(n+m) Representing the output signal after filtering by a time-varying low-pass filtery(n) HysteresismThe value corresponding to the time of day is,g(m) Is length ofMZero-valued linear structural elements of (1).
7. The TVLP-MF based dynamic checkweigher fast filtering method of claim 1, wherein the function expression estimated based on the output of the morphological filter in step 3) is:
in the above formula, the first and second carbon atoms are,Mis a weight value of the measured object,M cal in order to correct the weight of the weight used,Dthe object to be measured starts to leave the filter output value of the improved morphological filter IMF corresponding to the weighing band,D 0is the output value of the filtering in the idle state,D calis the filter output value of the correction weight.
8. A TVLP-MF based dynamic checkweigher fast filtering system comprising a microprocessor and a memory connected to each other, wherein the microprocessor or an upper computer connected to the microprocessor is programmed or configured to perform the steps of the TVLP-MF based dynamic checkweigher fast filtering method according to any one of claims 1 to 7.
9. A TVLP-IMF-based dynamic checkweigher device comprises a control unit, a feeding belt, a weighing belt and a sorting belt which are sequentially arranged along a straight line, wherein a weighing sensor is arranged on the lower side of the weighing belt, the control unit comprises a microprocessor and a memory which are mutually connected, a front photoelectric sensor is arranged above the feeding side of the weighing belt, a rear photoelectric sensor is arranged above the discharging side of the weighing belt, the output ends of the front photoelectric sensor, the rear photoelectric sensor and the weighing sensor are respectively connected with the microprocessor, and the microprocessor or an upper computer connected with the microprocessor is programmed or configured to execute the steps of the TVLP-MF-based dynamic checkweigher rapid filtering method according to any one of claims 1-7.
10. A computer readable storage medium having stored thereon a computer program programmed or configured to perform the TVLP-MF based dynamic checkweigher fast filtering method of any one of claims 1-7.
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