CN109490405B - Filtering method based on orthogonal basis function, signal processing device and ground marking system - Google Patents
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Abstract
The invention provides a filtering method based on an orthogonal basis function, a signal processing device and a ground marking system. The filtering method comprises the following steps: acquiring a magnetic signal; and filtering the magnetic signal by using a convolution factor based on an orthogonal basis function to obtain a filtered signal which is the product of the magnetic signal and the convolution factor. The orthogonal basis function-based filtering method, the signal processing device and the ground marking system provided by the invention utilize the convolution factor based on the orthogonal basis function to filter the magnetic signal, so that the signal to noise ratio of the filtered signal is higher after the filtering, and the accuracy of magnetic leakage judgment can be improved by utilizing the filtered signal.
Description
Technical Field
The present invention relates to the field of electronic information technologies, and in particular, to a filtering method, a signal processing device, and a ground marking system based on an orthogonal basis function.
Background
In order to ensure the safety and reliability of the pipeline transportation environment, a magnetic flux leakage inner detector is generally adopted in the pipeline detection industry to periodically detect whether the pipeline wall is corroded or not. During the operation of the intra-leakage-detector, it is indispensable to acquire the positional information of the intra-leakage-detector in real time. On the one hand, when the magnetic leakage inner detector is jammed and other accidents occur, the magnetic leakage inner detector can be positioned and salvaged in time through the position information of the magnetic leakage inner detector. On the other hand, the geographic position of the pipeline corrosion defect can be determined in an auxiliary mode according to the positioning position and time information of the ground marker.
The ground marker operates by determining whether the magnitude of the magnetic field generated by the magnetic pole of the intra-leakage detector in the vicinity of the ground surface exceeds a set threshold. When the magnetic field exceeds the threshold value, the inner magnetic leakage detector is indicated to pass through the pipeline below the ground marker, so that the aim of positioning the inner magnetic leakage detector in real time is fulfilled. However, the magnetic signal output by the conventional ground marker for threshold judgment is quite noisy, and the magnetic leakage condition cannot be accurately judged, so that the magnetic leakage position cannot be accurately positioned.
Disclosure of Invention
In view of the foregoing, it is desirable to provide a filtering method, a signal processing apparatus, and a ground marking system based on an orthogonal basis function, which have a high signal-to-noise ratio.
The invention provides a filtering method based on an orthogonal basis function, which comprises the following steps:
acquiring a magnetic signal;
and filtering the magnetic signal by using a convolution factor based on an orthogonal basis function to obtain a filtered signal which is the product of the magnetic signal and the convolution factor.
In one embodiment, the convolution factor has the expression h (n) = [ (nT) s /τ) 2 +1] -4 Wherein T is s In order to sample the period of time,for characteristic time, R 0 The detector device in the magnetic leakage moves to the nearest distance from the magnetic field detection device, and v is the moving speed of the magnetic field detector.
In one embodiment, the method for obtaining the convolution factor based on the orthogonal basis function includes:
obtaining a relation between the square of a mode of the dimensionless magnetic field strength and an unknown variable;
orthogonalizing the relation, and then obtaining an orthogonalization basis function through normalization calculation;
discretizing the orthogonal basis function to obtain the convolution factor based on the orthogonal basis function.
In one embodiment, the orthogonalization process is a glamer-schmitt orthogonalization process.
In one embodiment, the step of discretizing the orthogonal basis functions to obtain the convolution factor based on the orthogonal basis functions includes:
and discretizing the orthogonal basis function into a discretization expression of a discrete variable by using the product of the ratio of the sampling period to the characteristic time and the discrete variable as the unknown variable.
In one embodiment, before the step of obtaining a relation between the square of the modulus of the dimensionless magnetic field strength and the unknown variable, the method for obtaining the convolution factor based on the orthogonal basis function further includes:
acquiring the moving speed of the magnetic field detector and the nearest distance between the magnetic field detector and the ground marker in a preset coordinate system, and acquiring the position vector between the magnetic field detector and the ground marker according to the moving time;
acquiring a magnetic dipole moment of an object to be detected, and acquiring a magnetic induction intensity expression on the position vector according to the position vector and the magnetic dipole model;
and carrying out dimensionless treatment on the magnetic induction intensity expression through dimensionless unknown variables to obtain dimensionless magnetic field intensity.
In one embodiment, the dimensionless unknown variable is the ratio of the product of the speed of movement and time to the closest distance of the magnetic field detector from the surface marker.
The invention also provides a signal processing device based on the orthogonal basis function, which comprises:
the signal receiving module is used for receiving the magnetic signal;
the matched filtering module is electrically connected with the signal receiving module, is based on an orthogonal dominant basis function and filters the magnetic signals by adopting any filtering method based on the orthogonal basis function.
The invention also provides a ground marking system based on the orthogonal basis functions, which comprises:
the magnetic field detection device is used for collecting magnetic signals of a three-dimensional space around the object to be detected;
the signal processing device is electrically connected with the magnetic field detection device and is based on the orthogonal basis function;
and the positioning and communication device is electrically connected with the signal processing device and is used for transmitting the magnetic signals and the position information processed by the signal processing device to the remote monitoring terminal.
In one embodiment, the positioning and communication device comprises: the positioning module and the communication module are respectively and electrically connected with the signal processing device.
In one embodiment, the ground marking system based on orthogonal basis functions further comprises a power management device electrically connected with the electromagnetic detection device, the signal processing device, the positioning and communication device and the display device respectively.
In one embodiment, the ground marking system based on orthogonal basis functions further comprises an intra-magnetic leakage detector device arranged in the object to be measured for emitting a magnetic signal.
In one embodiment, the orthogonal basis function based ground marking system further comprises a display device electrically connected to the signal processing device.
According to the filtering method, the signal processing device and the ground marking system based on the orthogonal basis function, the convolution factor based on the orthogonal basis function is utilized to filter the magnetic signal, so that the signal-to-noise ratio of the filtered signal is higher after the filtering, and the accuracy of magnetic leakage judgment can be improved by utilizing the filtered signal.
Drawings
FIG. 1 is a flow chart of a method of orthogonal basis function based filtering according to one embodiment;
FIG. 2 is a flow chart of a method for obtaining convolution factors based on orthogonal basis functions in an orthogonal basis function based filtering method according to one embodiment;
FIG. 3 is a flow chart of a method for obtaining convolution factors based on orthogonal basis functions in another embodiment of a filtering method based on orthogonal basis functions;
FIG. 4 is a block diagram of a ground marking system based on orthogonal basis functions according to one embodiment;
FIG. 5 is a block diagram of another embodiment of an orthogonal basis function based ground marking system;
FIG. 6 is an application scenario diagram of an orthogonal basis function based ground marking system of one embodiment;
FIG. 7 is a graph of the evolution of three-dimensional orthogonal basis functions with dimensionless variables employed by an orthogonal basis function based ground marking system of one embodiment;
FIG. 8 is a schematic diagram of magnetic signals collected by the magnetic field detection device in an orthogonal basis function based surface marking system according to one embodiment;
fig. 9 is a schematic diagram showing a magnetic signal processed by the signal processing device after the magnetic signal collected by the magnetic field detecting device in the ground marking system based on the orthogonal basis function according to an embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the present invention.
Referring to fig. 1, an embodiment of the present invention provides a filtering method based on an orthogonal basis function, where the filtering method based on the orthogonal basis function includes the following steps:
s100, acquiring a magnetic signal;
and S200, filtering the magnetic signal by using a convolution factor based on an orthogonal basis function, and obtaining a filtered signal which is the product of the magnetic signal and the convolution factor.
Specifically, the magnetic signal is the magnetic signal of the position of the detector. In one embodiment, when the detector detects the pipeline to be detected, the magnetic signals are all magnetic signals collected by the detector, including magnetic signals sensed by the detector, magnetic signals released in the pipeline to be detected, earth magnetic signals and the like.
Specifically, the magnetic signal is filtered, and the expression of the filtered magnetic signal is:
where s (n) is the magnetic signal, h (n) is the convolution factor based on the orthogonal basis function, y (n) is the filtered magnetic signal, and n is the discretization factor.
According to the filtering method based on the orthogonal basis function, the convolution factor based on the orthogonal basis function is utilized to filter the magnetic signal, so that the signal-to-noise ratio of the filtered signal is higher after the filtering, and the accuracy of magnetic leakage judgment can be improved by utilizing the filtered signal.
Referring to fig. 2, in one embodiment, the method for obtaining the convolution factor based on the orthogonal basis function includes: in step S210, a relation between the square of the modulus of the dimensionless magnetic field strength and the unknown variable is obtained.
Specifically, a filtering method based on an orthogonal basis function is constructed, and a relational expression of the dimensionless magnetic field strength and an unknown variable is obtained first. The square of the modulus is then solved for the dimensionless magnetic field strength.
Step S220, orthogonalizing the relation, and obtaining an orthogonalization basis function through normalization calculation.
Specifically, the relational expression is decomposed based on orthogonal coordinates. Normalization is then performed to obtain orthogonal basis functions. The relationship can be seen as consisting of three basic equations:
where u is an unknown variable.
To better use the three equations to characterize the signal, the signal is subjected to a glamer-schmitt orthogonalization process, and the equations after the process are normalized as shown in the following formula:
this formula is called an orthogonal basis function. The evolution of which is shown in figure 7.
And step S230, discretizing the orthogonal basis function to obtain the convolution factor based on the orthogonal basis function.
Specifically, the orthogonal basis function containing the unknown variable is a continuous function, and the continuous function is discretized into a discretized expression of the discretized variable. And obtaining the convolution factor of the matched filtering algorithm through Fourier transformation. The convolution factor of the matched filtering algorithm is obtained by adopting the orthogonal basis function to carry out discretization, so that the signal to noise ratio of the magnetic signal after being processed by the convolution factor of the matched filtering algorithm is improved.
In one embodiment, the orthogonalization is a glamer-schmitt orthogonalization.
In one embodiment, the step S230 is:
and discretizing the orthogonal basis function into a discretization expression of a discrete variable by using the product of the ratio of the sampling period to the characteristic time and the discrete variable as the unknown variable.
Specifically, u=nt is employed s Discretizing the orthogonal basis function by tau, and then carrying out a matched filtering algorithm to obtain an expression of a convolution factor h (n) as follows:
h(n)＝[(nT s /τ) 2 +1] -4 ，
wherein T is s In order to sample the period of time,for characteristic time, R 0 The detector device in the magnetic leakage moves to the nearest distance from the magnetic field detection device, and v is the moving speed of the magnetic field detector.
Referring to fig. 3, in one embodiment, before the step of obtaining the relation between the square of the modulus of the dimensionless magnetic field strength and the unknown variable, the method for obtaining the convolution factor based on the orthogonal basis function further includes:
s201, the moving speed of the magnetic leakage inner detector device in the preset coordinate system and the nearest distance between the magnetic leakage inner detector device and the magnetic field detection device are obtained, and the position vector of the magnetic leakage inner detector device and the magnetic field detection device is obtained according to the moving time.
Specifically, a coordinate system is determined, and a position vector of the detector device in the magnetic leakage flux from the magnetic field detection device is expressed as:
wherein v is the moving speed of the magnetic field detector, t is the moving time of the magnetic field detector, R 0 The intra-leakage detector means is moved to a nearest distance from the magnetic field detection means.
S202, acquiring a magnetic dipole moment of an object to be detected, and acquiring a magnetic induction intensity expression on the position vector according to the position vector and the magnetic dipole model.
Specifically, the magnetic induction intensity expression of the magnetic dipole is:
wherein, the liquid crystal display device comprises a liquid crystal display device,for magnetic dipole moment>Is the distance of the detector device in the magnetic leakage from the ground marker.
S203, performing dimensionless treatment on the magnetic induction intensity expression through a dimensionless unknown variable to obtain dimensionless magnetic field intensity.
In one embodiment the dimensionless unknown variable is the ratio of the product of the speed of movement and time to the closest distance of the magnetic field detector from the surface marker.
Specifically, the dimensionless unknown variable is:dimensionless representation can also be performed by other transformation forms. The relationship that the obtained dimensionless magnetic field strength is a dimensionless variable u is as follows:
wherein m is x 、m y And m z Three-dimensional component of magnetic dipole moment, R 0 The detector means in the leakage flux is moved to a nearest distance mu from the magnetic field detection means 0 ＝4π×10 -7 H/m。
An embodiment of the present invention further provides a signal processing apparatus based on an orthogonal basis function, including:
the signal receiving module is used for receiving the magnetic signal;
the matched filtering module is electrically connected with the signal receiving module, is based on an orthogonal dominant basis function and filters the magnetic signals by adopting any filtering method based on the orthogonal basis function.
Referring to fig. 4, a ground marking system 10 based on orthogonal basis functions according to an embodiment of the present invention is further provided, including: a magnetic field detection device 100, a signal processing device 200, a positioning and communication device 300. The magnetic field detection device 100 is used for collecting magnetic signals of a three-dimensional space around the object to be detected. The signal processing device 200 is electrically connected to the magnetic field detecting device 100, and uses the method for acquiring a magnetic signal, so as to perform signal processing on the magnetic signal by a matched filtering method based on an orthogonal dominant basis function. The positioning and communication device 300 is electrically connected to the signal processing device 200, and is configured to send the magnetic signal and the position information processed by the signal processing device 200 to a remote monitoring terminal.
In one embodiment, the magnetic field detection device 100 is a three-axis digital magnetometer, which is connected to the signal processing device 200 through an SPI communication interface. The triaxial digital magnetometer collects magnetic signal data in three vertical directions in space in real time and sends the magnetic signal data to the signal processing device 200. The magnetic field detecting device 100 may be other magnetic field measuring devices such as a conductive coil.
The signal processing device 200 has embedded therein a matched filtering algorithm based on an orthogonal dominant basis function. The matched filtering algorithm based on the orthogonal dominant basis function is a mathematical model taking the orthogonalized dominant basis function as a target signal, and performs autocorrelation matched filtering on a synthesized signal of the triaxial space magnetic field, so that background noise interference is eliminated, and the target signal submerged in noise is effectively extracted.
In one embodiment, the positioning and communication device 300 comprises: a positioning module 410 and a communication module 420, the positioning module 410 and the communication module 420 being electrically connected to the signal processing device 200, respectively.
The communication module may be a GPRS communication module, a wifi communication module, or other wireless transmission module. And the positioning module 410 may be a GPS module or a beidou positioning module. The GPS module or the Beidou positioning module acquires GPS geographic position information of the ground marking system 10 based on the orthogonal basis function through an antenna. The GPRS communication module remotely transmits data to the control room via an antenna.
Specifically, the GPS module or the beidou positioning module receives the longitude, latitude and altitude information of the ground marking system 10 based on the orthogonal basis function through an antenna. In one embodiment, the GPRS communication module adopts a GPRS communication chip, and connects a network through a mobile phone SIM card and an antenna, so as to remotely send the system information acquired and processed by the ground marking system 10 based on the orthogonal basis function to a control room.
In one embodiment, the orthogonal basis function based ground marking system 10 further comprises a display device 400 electrically connected to the signal processing device 200. The display device 400 includes a display screen, an electric quantity indicator, and an alarm, which are electrically connected with the signal processing device 200, respectively. The display screen may be a color liquid crystal display screen. The alarm may be a buzzer. The color liquid crystal display is electrically connected to the signal processing device 200 for displaying system information of the device to a user. The buzzer generates an audible alarm when the magnetic signal detected by the signal processing apparatus 200 is present. The power indicator displays the remaining power of the orthogonal basis function-based ground marking system 10 in real time.
Referring to fig. 5, in one embodiment, the ground marking system 10 further includes a power management device 500 electrically connected to the electromagnetic detecting device 100, the signal processing device 200, the positioning and communication device 300 and the display device 400, respectively. Specifically, the power management device 500 provides three working voltages, namely 5V,3.3V and 1.8V, for the ground marking system 10 based on the orthogonal basis function at the same time, and other specific voltage values can be adopted according to practical situations. The power management device 500 provides operating voltages for the electromagnetic detecting device 100, the signal processing device 200, the positioning and communication device 300, and the display device 400. The electromagnetic detecting device 100 needs 3.3V, the display device 400 needs 5V, the positioning and communication device 300 needs 3.3V, the core chip of the signal processing device 200 needs 3.3V and 1.8V, and the port needs 5V.
In one embodiment, the orthogonal basis function based surface marking system further comprises a remote monitoring terminal 600 in communication with the positioning and communication device 300.
In one embodiment, the orthogonal basis function based surface marking system 10 further comprises an intra-leakage detector arrangement 700. The magnetic flux leakage inner detector device 700 is disposed in the object to be measured and is used for releasing magnetic signals. The intra-leakage detector means 700 comprises a magnetic field generating means, which may be a magnet. In one embodiment, the intra-magnetic leakage detector device 700 is configured to flow with a liquid within the test object. In one embodiment, the intra-leakage-flux detector device 700 may also be an intra-leakage-flux detection robot. The magnetic flux leakage inner detection robot is provided with a driving device to drive the magnetic flux leakage inner detection robot to move in the pipeline to be detected.
Fig. 6 shows a specific application scenario of the ground marking system based on the orthogonal basis functions. The electromagnetic detecting device 100 has a closest distance of 8m from the intra-leakage-detection device 700. The moving speed of the electromagnetic detecting device 100 is 5m/s. Fig. 7 shows a three-dimensional orthogonal basis function evolution diagram with dimensionless variables, which is used by the orthogonal basis function-based ground marking system. Fig. 8 shows the magnetic signals acquired by the magnetic field detection device in the orthogonal basis function based surface marking system 10. The signal-to-noise ratio of the received magnetic signal is-10.2273 dB, and the magnetic signal noise is high. Fig. 9 shows a filtered signal of the magnetic signal collected by the magnetic field detection device in the ground marking system 10 based on the orthogonal basis function after being processed by the signal processing device. That is, the received magnetic signal shown in fig. 7 is subjected to real-time matched filtering, so as to obtain a processed data normalized waveform diagram. At this time, the signal-to-noise ratio of the filtered signal after the matched filtering process was 7.95dB. Therefore, the ground marking device of the oil gas pipeline magnetic leakage internal detection robot based on the orthogonal dominant basis function matching can effectively improve the signal-to-noise ratio of the received signal in real time. According to actual requirements, other values can be adopted for the nearest distance and the moving speed in the application scene.
In the several embodiments provided in the present invention, it should be understood that the disclosed related apparatus and method may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, and the division of modules or units, for example, is merely a logical functional division, and there may be additional divisions when actually implemented, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional unit in the embodiments of the present invention may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.
Those skilled in the art will appreciate that implementing all or part of the processes of the methods of the embodiments described above may be accomplished by computer programs stored on a computer readable storage medium, such as a computer system, and executed by at least one processor in the computer system to implement processes including embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a random-access Memory (Random Access Memory, RAM), or the like.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (11)
1. A method of filtering based on orthogonal basis functions, comprising:
acquiring a magnetic signal; obtaining a relation between the square of a mode of the dimensionless magnetic field strength and an unknown variable; orthogonalizing the relation, and then obtaining an orthogonalization basis function through normalization calculation; discretizing the orthogonal basis function to obtain the convolution factor based on the orthogonal basis function;
filtering the magnetic signal by using a convolution factor based on an orthogonal basis function to obtain a filtered signal which is the product of the magnetic signal and the convolution factor; the expression of the convolution factor is h (n) = [ (nT) s /τ) 2 +1] -4 Wherein T is s In order to sample the period of time,for characteristic time, R 0 The detector device in the magnetic leakage moves to the nearest distance from the magnetic field detection device, v is the moving speed of the magnetic field detector, and n is a discretization factor.
2. The filtering method of claim 1, wherein the orthogonalization process is a glamer-schmitt orthogonalization process.
3. The filtering method of claim 1, wherein the step of discretizing the orthogonal basis functions to obtain the orthogonal basis function-based convolution factor is:
and discretizing the orthogonal basis function into a discretization expression of a discrete variable by using the product of the ratio of the sampling period to the characteristic time and the discrete variable as the unknown variable.
4. The filtering method according to claim 1, wherein, before the step of obtaining a relation between the square of the modulus of the dimensionless magnetic field strength and the unknown variable, the method of obtaining the convolution factor based on the orthogonal basis function further includes:
acquiring the moving speed of the magnetic field detector and the nearest distance between the magnetic field detector and the ground marker in a preset coordinate system, and acquiring the position vector between the magnetic field detector and the ground marker according to the moving time;
acquiring a magnetic dipole moment of an object to be detected, and acquiring a magnetic induction intensity expression on the position vector according to the position vector and the magnetic dipole model;
and carrying out dimensionless treatment on the magnetic induction intensity expression through dimensionless unknown variables to obtain dimensionless magnetic field intensity.
5. The filtering method of claim 4, wherein the dimensionless unknown variable is a ratio of a product of the moving speed and time to a closest distance of the magnetic field detector from the surface marker.
6. A signal processing apparatus based on orthogonal basis functions, comprising:
the signal receiving module is used for receiving the magnetic signal;
the matched filtering module is electrically connected with the signal receiving module, is based on an orthogonal dominant basis function and filters the magnetic signals by adopting the filtering method according to any one of claims 1-5.
7. A ground marking system based on orthogonal basis functions, the system comprising:
the magnetic field detection device is used for collecting magnetic signals of a three-dimensional space around the object to be detected;
signal processing means electrically connected to the magnetic field detection means, the signal processing means being the orthogonal basis function-based signal processing means of claim 6;
and the positioning and communication device is electrically connected with the signal processing device and is used for transmitting the magnetic signals and the position information processed by the signal processing device to the remote monitoring terminal.
8. The floor marking system of claim 7, wherein the locating and communication device comprises: the positioning module and the communication module are respectively and electrically connected with the signal processing device.
9. The floor marking system of claim 7, further comprising a power management device electrically connected to the magnetic field detection device, the signal processing device, the positioning and communication device, and the display device, respectively.
10. The surface marking system of claim 7, further comprising an intra-magnetic leakage detector device disposed within the test object for emitting a magnetic signal.
11. The floor marking system of claim 7, further comprising a display device electrically connected to the signal processing device.
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