CN115163319B - Digital information transmission method for electric control single-cylinder diesel engine - Google Patents
Digital information transmission method for electric control single-cylinder diesel engine Download PDFInfo
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/0002—Controlling intake air
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
- F02D35/02—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions
- F02D35/023—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions by determining the cylinder pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
- F02D35/02—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions
- F02D35/027—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions using knock sensors
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/40—Engine management systems
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Abstract
The invention relates to the technical field of digital information transmission, in particular to a digital information transmission method for an electronic control single-cylinder diesel engine. The method obtains a cylinder body vibration signal from the seating process of an intake valve of the single-cylinder diesel engine to the combustion and explosion process of a cylinder, and divides the cylinder body vibration signal into a high-frequency signal and a low-frequency signal. And screening out noise signal points in the high-frequency signal through a standard vibration attenuation constraint condition. And acquiring a high-frequency correction reference index in the high-frequency signal and a low-frequency correction reference index in the low-frequency signal under the time domain position of the noise signal point, and further judging whether amplitude modulation is needed. The invention modulates the amplitude of the noise signal point in the high-frequency signal by the low-frequency signal, so that the information in the modulated signal is more complete, and the transmission of high-quality digital information at the signal receiving end is realized.
Description
Technical Field
The invention relates to the technical field of digital information transmission, in particular to a digital information transmission method for an electronic control single-cylinder diesel engine.
Background
The diesel engine is a power machine with relatively high heat efficiency. It adopts high-pressure fuel injection pump and fuel injection nozzle including advancing device to inject proper quantity of fuel into combustion chamber of diesel engine at proper time and in proper space state so as to create optimum fuel and air mixed combustion optimum favorable condition. The diesel injection has high precision requirement on the injection timing, so the key and difficulty of the diesel engine electric control technology is that the main control quantity of the diesel injection electric control actuator, namely an electric control diesel injection system, is the injection timing.
In the prior art, a plurality of vibration signal acquisition sensors are arranged on a cylinder cover and screws of the diesel engine to acquire the diesel combustion condition of a combustion chamber of the diesel engine, so that the most appropriate fuel injection timing is calculated. Because the wired transmission sensor signal needs better wiring environment, otherwise faults such as stranded wires, short circuits and the like easily occur, and the debugging and maintenance are troublesome, so that a wireless transmission technology is mostly selected. Compared with wired transmission, the wireless transmission is more flexible, has strong expansibility and does not occupy the internal space of the diesel engine, but has poor anti-interference capability, and can possibly cause slow diesel injection or injection amount calculation error if the wireless transmission is directly carried out on the vibration signals.
Disclosure of Invention
In order to solve the technical problems, the invention aims to provide a digital information transmission method for an electric control single-cylinder diesel engine, which adopts the following technical scheme:
the invention provides a digital information transmission method for an electronic control single cylinder diesel, which comprises the following steps:
obtaining a cylinder body vibration signal from the seating process of an inlet valve of the single-cylinder diesel engine to the combustion and explosion process of a cylinder; decomposing the cylinder body vibration signal into a low-frequency signal and a high-frequency signal;
if the signal point in the high-frequency signal meets the standard vibration attenuation constraint condition, the signal point is considered to be a normal signal point, otherwise, the signal point is considered to be a noise signal point; the standard vibration attenuation constraints comprise a first constraint, a second constraint and a third constraint; the first constraint condition determines a high-frequency amplitude salient point and a corresponding high-frequency attenuation end point according to the amplitude of the signal point; the second constraint condition is used for limiting the amplitude of a signal point between the high-frequency amplitude salient point and the high-frequency attenuation end point to be in a continuously decreasing state; the third constraint condition is used for limiting the amplitude of the signal point between the high-frequency amplitude salient point and the high-frequency attenuation end point to be decreased to meet high-frequency Gaussian distribution;
obtaining a first time domain information difference between the noise signal point and the high-frequency amplitude salient point, obtaining a corresponding standard amplitude in the high-frequency Gaussian distribution according to the time domain position of the noise signal point, obtaining a first amplitude difference between the noise signal point and the standard amplitude, and obtaining a high-frequency correction reference index according to the first amplitude difference and the first time domain information difference; obtaining a low-frequency and high-frequency amplitude salient point, a low-frequency and high-frequency attenuation end point and low-frequency Gaussian distribution of the low-frequency signal, obtaining a second time domain information difference and a second amplitude difference of a corresponding signal point of the noise signal point in the low-frequency signal, and obtaining a low-frequency correction reference index according to the second amplitude difference and the second time domain information difference; if the low-frequency correction reference index is larger than the high-frequency correction reference index, taking the amplitude of the corresponding signal point in the low-frequency signal as the amplitude of the noise signal point in the high-frequency signal to obtain a modulation signal; and transmitting the modulation signal to a receiving end.
Further, the obtaining of the cylinder vibration signal from the seating process of the air inlet valve of the single-cylinder diesel engine to the combustion explosion process of the cylinder comprises the following steps:
obtaining a complete cylinder body vibration signal and a cylinder pressure signal in the complete combustion and explosion process of the diesel engine; and acquiring a time period from the seating process of the intake valve to the combustion and explosion process of the cylinder by using the in-cylinder pressure signal, and intercepting the vibration signal of the complete cylinder body according to the time period to acquire the vibration signal of the cylinder body.
Further, the decomposing the cylinder vibration signal into a low frequency signal and a high frequency signal includes:
and processing the cylinder body vibration signal by utilizing wavelet transformation to obtain the low-frequency signal and the high-frequency signal.
Further, the first constraint condition includes:
traversing signal points on the whole high-frequency signal according to a time domain sequence; if the ratio of the amplitude of the signal point to the amplitude of the signal point at the previous moment is more than or equal to a preset amplitude multiple, the signal point is considered as the high-frequency amplitude salient point; if the amplitude of the signal point is in the preset neighborhood range of 0, the signal point is considered as the high-frequency attenuation end point; and taking the high-frequency attenuation end point closest to the high-frequency amplitude convex excitation point as the corresponding high-frequency attenuation end point.
Further, the second constraint condition includes:
and if the difference value between the amplitude of the signal point at the later moment of the signal point on the high-frequency signal and the amplitude of the signal point is a negative number, the continuous decreasing state is considered to be met.
Further, the expression of the third constraint includes:
wherein, the first and the second end of the pipe are connected with each other,
is a functional model of the high frequency gaussian distribution,
is a first
Signal pointThe time-domain information of (a) is,
time domain information of the high frequency amplitude bump point,
time domain information of the end point of the high frequency attenuation,
is an exponential function with a natural constant as the base,
the amplitude of the high frequency amplitude bump point,
in order to be a function of the error adjustment,
is as follows
The amplitude of the signal point is determined,
and the number of signal points from the high-frequency amplitude bump point to the high-frequency attenuation end point is calculated.
Further, the method for screening the noise signal points by using the standard vibration attenuation constraint condition comprises the following steps:
sequentially carrying out a detection process on each signal point of the high-frequency signal by using the first constraint condition, the second constraint condition and the third constraint condition; the detection process detects the signal points of the high-frequency signal one by one in a time domain;
if the detection process detects an abnormal signal point, recording the position of the abnormal signal point and skipping the abnormal signal point to continue executing the detection process;
if a continuous preset number of abnormal signal points appear, the continuous abnormal signal points are regarded as the normal signal points; otherwise, the abnormal signal point is considered as the noise signal point.
Further, the obtaining a high-frequency correction reference index according to the first amplitude difference and the first time domain information difference comprises:
obtaining the high-frequency correction reference index by using a high-frequency correction reference index formula, wherein the high-frequency correction reference index formula comprises:
wherein the content of the first and second substances,
for the purpose of correcting the reference index for the high frequency,
is a natural constant and is a natural constant,
is as follows
Time domain information of each of said noise signal points,
time domain information of the high frequency amplitude bump point,
is as follows
The amplitude of each of said noise signal points,
is a first
The standard amplitude corresponding to each noise signal point in the high-frequency Gaussian distribution;
obtaining a low-frequency correction reference index by using a low-frequency correction reference index formula, wherein the low-frequency correction reference index formula comprises:
wherein, the first and the second end of the pipe are connected with each other,
the reference indicator is corrected for the low frequency,
is a natural constant and is a natural constant,
is as follows
Time domain information of each of said noise signal points,
is the time domain information of the low-frequency high-frequency amplitude salient point,
is the amplitude of the corresponding signal point of the noise signal point in the low frequency signal,
the standard amplitude values corresponding to the corresponding signal points in the low-frequency Gaussian distribution are obtained.
Further, the transmitting the modulated signal to a receiving end includes:
sampling on the modulation signal by using a preset initial number of sampling points, carrying out binary coding transmission, and transmitting to a signal receiving end to obtain a received signal; taking the length ratio of the modulation signal to the receiving signal as a compression rate; obtaining the ratio of the amplitude of each signal point of the modulation signal to the amplitude of each signal point of the receiving signal, and taking the average ratio as a distortion rate; weighting and summing the compression rate and the distortion rate to obtain an encoding error index; and if the coding error index is larger than a preset index threshold value, increasing the number of the sampling points until the coding error index is not larger than the index threshold value.
The invention has the following beneficial effects:
according to the explosion characteristic of the diesel engine, a cylinder body vibration signal from a cylinder inlet valve seating process to a cylinder combustion explosion process is intercepted. And only amplitude modulation is carried out on the section of signal, so that the calculation amount is effectively reduced, and the accurate processing of the signal is realized. And further splitting the cylinder vibration signal into a high-frequency signal and a low-frequency signal, screening out a noise signal point in the high-frequency signal according to the signal characteristic in the high-frequency signal, and judging whether amplitude modulation needs to be carried out on the high-frequency signal or not by comparing the corrected reference indexes of the high-frequency signal and the low-frequency signal at the time domain position of the noise signal point. Whether the high-frequency signal or the low-frequency signal at a certain time domain position meets the standard vibration attenuation distribution or not can be judged through correcting the reference index, the high-frequency signal can be modulated based on the low-frequency signal, the final modulation signal not only contains the characteristics of the high-frequency signal but also contains the characteristics of the low-frequency signal, the modulation signal is transmitted, and the control terminal can effectively and accurately control the oil injection timing of the diesel engine through analyzing the modulation signal.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions and advantages of the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a flow chart of a method for transmitting digital information for an electronically controlled single cylinder diesel engine according to an embodiment of the present invention;
FIG. 2 is a graph illustrating a signal of a period of oscillation during a combustion burst of a diesel engine according to an embodiment of the present invention;
FIG. 3 is a signal of in-cylinder pressure cycles during an explosion of a diesel engine provided in accordance with an embodiment of the present invention;
FIG. 4 is a low frequency signal of a vibration signal according to an embodiment of the present invention;
fig. 5 shows a high frequency signal of a vibration signal according to an embodiment of the present invention.
Detailed Description
In order to further explain the technical means and effects of the present invention adopted to achieve the predetermined object, the following detailed description, with reference to the accompanying drawings and preferred embodiments, describes a digital information transmission method for an electronically controlled single cylinder diesel engine according to the present invention, and the specific implementation, structure, features and effects thereof. In the following description, the different references to "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
The following describes a specific scheme of the digital information transmission method for the electronically controlled single cylinder diesel engine in detail by combining with the attached drawings.
Referring to fig. 1, a flow chart of a digital information transmission method for an electronically controlled single cylinder diesel engine according to an embodiment of the present invention is shown, where the method includes:
step S1: obtaining a cylinder body vibration signal from a seating process of an inlet valve of a single-cylinder diesel engine to a combustion and explosion process of a cylinder; the vibration signal of the cylinder body is decomposed into a low-frequency signal and a high-frequency signal.
In the embodiment of the invention, the vibration signal acquisition sensor is arranged on the cylinder cover of the diesel engine, the sensors are arranged at different positions of the cylinder body to acquire signals with different characteristics, such as the center of the cylinder cover, the edge of the cylinder cover, engine screws and the like, an implementer can set a plurality of signal acquisition points according to a specific implementation scene, and finally, the control terminal is used for carrying out combined analysis on transmitted signals to obtain accurate fuel injection timing. It should be noted that the vibration signals at different positions need to be processed by the same amplitude modulation method, and only one vibration signal is described in the following description of the embodiment of the present invention.
In the embodiment of the invention, in order to ensure that the signal has more accuracy, the stable rotating speed of the diesel engine is required to be ensured to be consistent with the whole diesel engine in the signal acquisition process, so that the signal acquisition is carried out after the diesel engine is preheated for 5 minutes.
The diesel engine is a cycle process in the process of fuel oil explosion, each cycle process comprises a plurality of sub-processes, and the method specifically comprises the following steps: 1. an inlet valve is opened to suck air; 2. seating an inlet valve, and finishing the air suction process; 3. the cylinder is exploded by combustion, and oil is injected for ignition; 4. the exhaust valve is opened to discharge waste gas; 5. the exhaust valve is seated and closed. Since the essential purpose of the acquisition signal is to control the timing of the injection by the electronic control unit, the most important process of information analysis during the whole cycle is the cylinder vibration signal from the intake valve seating process to the cylinder combustion explosion process. Because the vibration signal is a continuous signal in a time sequence, the whole periodic signal needs to be intercepted when signal acquisition is carried out, and the cylinder body vibration signal from the intake valve seating process to the cylinder combustion explosion process is intercepted.
Because the information in the vibration signal is complex, directly intercepting the signal is prone to deviation, and the intercepted signal is not the most effective signal. In the combustion and explosion stage of the diesel engine cylinder, the in-cylinder pressure has obvious characteristics, so that the time period required to be intercepted can be identified according to the pressure signal on the corresponding time sequence of the vibration signal, and the vibration signal of the complete cylinder body and the in-cylinder pressure signal in the complete combustion and explosion process of the diesel engine are obtained. Referring to fig. 2, a vibration period signal of a combustion burst of a diesel engine according to an embodiment of the present invention is shown; referring to fig. 3, a signal of in-cylinder pressure cycles during a combustion explosion of a diesel engine according to an embodiment of the present invention is shown. Since the combustion burst of the diesel engine is a periodic process, both fig. 2 and 3 are periodic signals. Because the sub-process when the burning is broken out is more, consequently to vibration signal and pressure signal, all contain the chronogenesis process that the multistage amplitude is different, combine vibration signal and pressure signal can obtain the characteristic of every process, specific characteristics include:
the cylinder body is stressed maximally in the combustion and explosion process of the cylinder, the vibration amplitude of the cylinder body is also maximized, and the attenuation process is longer; the degree of vibration of the door closing and seating process of the air suction valve and the exhaust valve is slightly larger relative to the vibration of the door opening process of the air suction valve and the exhaust valve, and the vibration interval is kept fixed.
Because the electronic control device controls the oil injection timing to mainly occur between the seating process of the air inlet valve and the combustion and explosion process of the cylinder, the vibration signal of the section needs to be intercepted, as can be seen from fig. 3, an obvious peak point can appear in a pressure periodic signal, the peak point corresponds to the combustion and explosion stage of the cylinder, the time period from the seating process of the air inlet valve to the combustion and explosion process of the cylinder can be obtained according to the peak value and the vibration amplitude of the corresponding pressure amplitude by reasoning forwards at the moment, and the required vibration signal of the cylinder can be obtained by intercepting the vibration signal of the complete cylinder body in a complete period according to the time period. It should be noted that, as shown in fig. 2, in combination with the characteristics of the pressure signal, the occurrence time corresponding to each sub-process in fig. 2 can be obtained, and the corresponding sub-process time can be obtained and the signal can be intercepted in each period, and for convenience of description, only one period process is taken as an example, in fig. 2, the process a is a cylinder combustion explosion process, the process B is an exhaust valve opening process, the process C is an exhaust valve seating process, the process D is an intake valve opening process, and the process E is an intake valve seating process.
The diesel engine is probably influenced by the vibration of other devices in the normal operation process simultaneously, because the acceleration of the vertical motion of the cylinder cover is large, the vibration change is stable, and therefore the high-frequency information in the vibration signal of the cylinder body cannot be influenced by the vibration noise. However, as the cylinder vibration is attenuated, a large noise influence may occur in the low frequency characteristic of the cylinder signal. Similarly, other random noise also has a phenomenon that a high-frequency characteristic has a large influence and a low-frequency characteristic is normal. Considering that the vibration characteristics in the high-frequency signal are obvious and are more stable relative to the low-frequency signal, the amplitude of the high-frequency signal is modulated by combining the characteristics of the low-frequency signal on the basis of the high-frequency signal, and the noise influence in the high-frequency signal is removed.
Preferably, the cylinder vibration signal is processed by wavelet transform to obtain a low frequency signal and a high frequency signal. Wavelet transforms are well known in the art and will not be described in further detail herein. Referring to fig. 4, a low frequency signal of a vibration signal according to an embodiment of the invention is shown. Referring to fig. 5, a high frequency signal of a vibration signal according to an embodiment of the invention is shown. Note that, for convenience, the signals in fig. 4 and 5 are vibration signals with complete cylinders, and are not cylinder vibration signals after being truncated. From the comparison between fig. 4 and fig. 5, it can be seen that the complete period of each group of vibration in the high frequency signal is shorter than that of the low frequency signal, and the signal continuity is better and more stable.
Step S2: and if the signal points in the high-frequency signals meet the standard vibration attenuation constraint condition, the high-frequency signals are regarded as normal signal points, otherwise, the high-frequency signals are regarded as noise signal points.
Each section of vibration of the cylinder body is a process of gradually attenuating the amplitude, and because low-frequency characteristics do not exist in the high-frequency signal, each section of vibration in the high-frequency signal can be attenuated to be 0 or the neighborhood of 0. And establishing standard vibration attenuation constraint conditions according to the attenuation characteristics. If the signal points in the high-frequency signals meet the standard vibration attenuation constraint conditions, the signals are considered to be normal signal points, otherwise, the signals are considered to be noise signal points. The standard vibration attenuation constraints specifically include:
(1) A first constraint. The first constraint condition is used for determining a high-frequency amplitude salient point and a corresponding high-frequency attenuation end point according to the amplitude of the high-frequency signal point, and specifically comprises the following steps: the signal points on the entire high frequency signal are traversed according to the time domain sequence. And if the ratio of the amplitude of the signal point to the amplitude of the signal point at the previous moment is more than or equal to a preset amplitude multiple, the signal point is considered as a high-frequency amplitude salient point. And if the amplitude of the signal point is in the preset neighborhood range of 0, the signal point is considered as a high-frequency attenuation end point. And taking a high-frequency attenuation end point closest to the high-frequency amplitude bump point as a corresponding high-frequency attenuation end point, namely taking a high-frequency amplitude bump point to a high-frequency attenuation end point as an attenuation wave band. It should be noted that a plurality of attenuation bands can be obtained through the first constraint condition, each attenuation band is processed by the same constraint condition in the subsequent process, and a noise abnormal point is obtained, which is only described by a section of attenuation band. In the embodiment of the present invention, the amplitude multiple is set to 2, and the neighborhood range is set to (1, -1).
(2) The second constraint condition is used for limiting the amplitude of a signal point between a high-frequency amplitude bump point and a high-frequency attenuation end point to be in a continuous decreasing state, and specifically comprises the following steps: and if the difference value between the amplitude of the signal point at the later moment of the signal point on the high-frequency signal and the amplitude of the signal point is a negative number, the continuous decreasing state is considered to be satisfied.
(3) And the third constraint condition is used for limiting the amplitude of the signal point between the high-frequency amplitude bump point and the high-frequency attenuation end point to be decreased to meet the high-frequency Gaussian distribution. Each attenuation band is a decreasing process, so that the decreasing band on the right side of the peak value of the common Gaussian function is selected for high-frequency Gaussian distribution, and the Gaussian function is well known by the technical personnel in the field and can be obtained through the amplitude and time corresponding to the high-frequency amplitude salient point and the high-frequency attenuation end point. The specific expression of the third constraint includes:
wherein the content of the first and second substances,
is a functional model of the high frequency gaussian distribution,
is as follows
The time-domain information of the signal point,
time domain information of the high frequency amplitude bump point,
time domain information of the end point of the high frequency attenuation,
is an exponential function with a natural constant as the base,
the amplitude of the high frequency amplitude bump point,
in order to be a function of the error adjustment,
is a first
The amplitude of the signal point is determined,
and the number of signal points between the high-frequency amplitude bump point and the high-frequency attenuation end point is counted. Namely, the third constraint condition is essentially: considering the amplitude corresponding to the high-frequency Gaussian distribution as a standard amplitude, if the amplitude corresponding to the signal point in the high-frequency signal is in the standard amplitudeAnd if the error range of the value is within the error range, the signal point is considered to meet the third constraint condition.
And judging each signal point on the high-frequency signal through a standard vibration attenuation constraint condition, wherein the signal point meeting the constraint condition is a normal signal point, and otherwise, the signal point is a noise signal point. Preferably, the process of specifically screening the noise signal points includes:
and sequentially carrying out a detection process on each signal point of the high-frequency signal by utilizing the first constraint condition, the second constraint condition and the third constraint condition. The detection process detects signal points of the high-frequency signal one by one in the time domain. Firstly, determining each attenuation wave band by using a first constraint condition, then, carrying out degressive judgment on signal points on the attenuation wave bands by using a second constraint condition, and if non-degressive signals occur, determining that abnormal signal points occur; otherwise, the third constraint condition is continuously utilized to judge the specific decreasing state of each signal point, if the high-frequency Gaussian distribution is met, the signal point is regarded as a normal signal point, and if the high-frequency Gaussian distribution is not met, the signal point is regarded as an abnormal signal point.
If the abnormal signal point is detected in the detection process, recording the position of the abnormal signal point and skipping the abnormal signal point to continue the detection process.
And if a continuous preset number of abnormal signal points appear, considering the continuous abnormal signal points as normal signal points. Otherwise, the abnormal signal point is considered as the noise signal point. It should be noted that the continuous occurrence of multiple abnormal signal points indicates that the band composed of the continuous abnormal signal points is an abnormal band, and the abnormal information of the band needs to be analyzed in the control terminal, and is not an occurring noise point, so that the signal point corresponding to the abnormal band is still considered as a normal signal point.
And step S3: acquiring a first time domain information difference between a noise signal point and a high-frequency amplitude salient point, acquiring a corresponding standard amplitude in high-frequency Gaussian distribution according to a time domain position of the noise signal point, acquiring a first amplitude difference between the noise signal point and the standard amplitude, and acquiring a high-frequency correction reference index according to the first amplitude difference and the first time domain information difference; acquiring a low-frequency high-frequency amplitude salient point, a low-frequency high-frequency attenuation end point and low-frequency Gaussian distribution of the low-frequency signal, acquiring a second time domain information difference and a second amplitude difference of a corresponding signal point of the noise signal point in the low-frequency signal, and acquiring a low-frequency correction reference index according to the second amplitude difference and the second time domain information difference; if the low-frequency correction reference index is larger than the high-frequency correction reference index, taking the amplitude of the corresponding signal point in the low-frequency signal as the amplitude of the noise signal point in the high-frequency signal to obtain a modulation signal; the modulated signal is transmitted to a receiving end.
Because the high-frequency signal and the low-frequency signal have noise signals with different contents and different positions, wherein the noise of the high-frequency signal is less, but the amplitude is abnormal due to the influence of the noise on the vibration attenuation wave band, the abnormal position in the high-frequency signal may not be abnormal in the low-frequency signal, and the low-frequency signal is more in line with the attenuation rule of the vibration signal, so that whether the amplitude modulation is performed on the noise signal point can be judged according to the comparison result by comparing the characteristics presented by the noise signal point in the high-frequency signal with the characteristics presented by the low-frequency signal at the corresponding time domain position.
The high-frequency signal has more information on the initial position of one wave band vibration and the information is more accurate; the information at the location of the subsequent attenuation of the low frequency signal for one band of vibrations is more and more accurate relative to the high frequency information. Therefore, the position of the noise signal point on an attenuation band and the difference relative to the standard amplitude can represent the characteristics of the noise point on the signal. The method for obtaining the high-frequency correction reference index of the noise signal point in the high-frequency signal and the low-frequency correction reference index of the corresponding time domain position in the low-frequency signal respectively comprises the following steps:
obtaining a high-frequency correction reference index by using a high-frequency correction reference index formula, wherein the high-frequency correction reference index formula comprises the following components:
wherein the content of the first and second substances,
in order to correct the reference index for high frequencies,
is a natural constant and is a natural constant,
is as follows
The time domain information of the individual noise signal points,
is the time domain information of the high frequency amplitude bump point,
is as follows
The amplitude of each of the noise signal points,
is as follows
The corresponding standard amplitude of each noise signal point in the high-frequency Gaussian distribution.
Obtaining a low-frequency correction reference index by using a low-frequency correction reference index formula, wherein the low-frequency correction reference index formula comprises:
wherein the content of the first and second substances,
in order to correct the reference index for low frequencies,
is a natural constant and is a natural constant,
is as follows
The time domain information of the individual noise signal points,
time domain information of the low-frequency and high-frequency amplitude bump point,
is the amplitude of the corresponding signal point of the noise signal point in the low frequency signal,
the corresponding standard amplitude in the low frequency gaussian distribution for the corresponding signal point.
When calculating the low-frequency correction reference index, it is necessary to obtain a low-frequency and high-frequency amplitude salient point, a low-frequency and high-frequency attenuation end point, and a low-frequency gaussian distribution of the low-frequency signal in advance. The obtaining method is the same as the obtaining method of the corresponding parameter of the high frequency signal, and is not described herein.
If the low-frequency correction reference index is larger than the high-frequency correction reference index, the characteristic of the low-frequency signal at the time domain position of the noise signal point in the high-frequency signal is more consistent with the standard distribution, and the information is more accurate, so that the amplitude of the corresponding signal point in the low-frequency signal is used as the amplitude of the noise signal point in the high-frequency signal, the amplitude modulation is realized, and the modulation signal is obtained.
If the low-frequency correction reference index is not greater than the high-frequency correction reference index, the obvious abnormality is shown, the noise is not generated, modulation processing is not needed, namely the abnormality information is reserved, and analysis is provided for a subsequent control terminal.
The modulation signal is based on the high-frequency characteristic, the low-frequency characteristic is used as a corrected signal, the internal noise is less, the information characteristic is obvious, and the condition of information blurring is not easy to occur in the transmission process. It should be noted that, when the control terminal transmits a signal, the modulation signal and signals generated by other sub-processes need to be transmitted together, because the main occurrence time of the electronic control device controlling the fuel injection timing is in the time sequence process corresponding to the modulation signal, the number of sampling points of the modulation signal during transmission is set to be large, and the integrity of information is ensured. Preferably, the number of sampling points can be adjusted according to transmission quality in the signal transmission process, and the method specifically includes:
sampling is carried out on the modulation signal by utilizing a preset initial number of sampling points, binary coding transmission is carried out, and the binary coding transmission is transmitted to a signal receiving end to obtain a receiving signal. The length ratio of the modulation signal to the received signal is used as the compression rate. And obtaining the ratio of the amplitude of each signal point of the modulation signal to the amplitude of each signal point of the receiving signal, and taking the average ratio as the distortion rate. And weighting and summing the compression rate and the distortion rate to obtain an encoding error index. And if the coding error index is larger than the preset index threshold, increasing the number of the sampling points until the coding error index is not larger than the index threshold. It should be noted that the compression ratio weight, the distortion ratio weight, and the index threshold may all be adjusted according to the computation capability of the control terminal in the specific implementation scenario, that is, the greater the computation capability is, the more sampling points are used, and the specific numerical value is not limited herein.
In summary, the embodiment of the invention obtains the cylinder vibration signal from the seating process of the intake valve of the single-cylinder diesel engine to the combustion and explosion process of the cylinder, and divides the cylinder vibration signal into a high-frequency signal and a low-frequency signal. And screening out noise signal points in the high-frequency signal through a standard vibration attenuation constraint condition. And acquiring a high-frequency correction reference index in the high-frequency signal and a low-frequency correction reference index in the low-frequency signal under the time domain position of the noise signal point, and further judging whether amplitude modulation is needed. According to the embodiment of the invention, the amplitude modulation is carried out on the noise signal point in the high-frequency signal through the low-frequency signal, so that the information in the modulation signal is more complete, and the high-quality digital information transmission of the signal receiving end is realized.
It should be noted that: the sequence of the above embodiments of the present invention is only for description, and does not represent the advantages or disadvantages of the embodiments. The processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing may also be possible or may be advantageous.
All the embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from other embodiments.
The present invention is not limited to the above preferred embodiments, and any modifications, equivalent replacements, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (6)
1. A digital information transmission method for an electronically controlled single cylinder diesel engine, the method comprising:
obtaining a cylinder body vibration signal from a seating process of an inlet valve of a single-cylinder diesel engine to a combustion and explosion process of a cylinder; decomposing the cylinder body vibration signal into a low-frequency signal and a high-frequency signal;
if the signal point in the high-frequency signal meets the standard vibration attenuation constraint condition, the signal point is considered to be a normal signal point, otherwise, the signal point is considered to be a noise signal point; the standard vibration attenuation constraints comprise a first constraint, a second constraint and a third constraint; the first constraint condition determines a high-frequency amplitude salient point and a corresponding high-frequency attenuation end point according to the signal point amplitude, and specifically includes: traversing signal points on the whole high-frequency signal according to a time domain sequence; if the ratio of the amplitude of the signal point to the amplitude of the signal point at the previous moment is more than or equal to a preset amplitude multiple, the signal point is considered as the high-frequency amplitude salient point; if the amplitude of the signal point is in the preset neighborhood range of 0, the signal point is considered as the high-frequency attenuation end point; taking the high-frequency attenuation end point closest to the high-frequency amplitude convex excitation point as the corresponding high-frequency attenuation end point; the second constraint condition is used for limiting the amplitude of the signal point between the high-frequency amplitude salient point and the high-frequency attenuation end point to be in a continuously decreasing state, and specifically includes: if the difference value between the amplitude of the signal point at the later moment of the signal point on the high-frequency signal and the amplitude of the signal point is a negative number, the continuous decreasing state is considered to be met; the third constraint condition is used for limiting the decreasing of the amplitude of the signal point between the high-frequency amplitude salient point and the high-frequency attenuation end point to meet a high-frequency Gaussian distribution, and the expression of the third constraint condition comprises:
wherein the content of the first and second substances,
is a functional model of the high frequency gaussian distribution,
is a first
The time-domain information of the signal point,
time domain information of the high frequency amplitude bump point,
time domain information of the end point of the high frequency attenuation,
is an exponential function with a natural constant as the base,
the amplitude of the high frequency amplitude bump point,
in order to be a function of the error adjustment,
is as follows
The amplitude of the signal point is determined,
the number of signal points between the high-frequency amplitude bump point and the high-frequency attenuation end point is set;
obtaining a first time domain information difference between the noise signal point and the high-frequency amplitude salient point, obtaining a corresponding standard amplitude in the high-frequency Gaussian distribution according to the time domain position of the noise signal point, obtaining a first amplitude difference between the noise signal point and the standard amplitude, and obtaining a high-frequency correction reference index according to the first amplitude difference and the first time domain information difference; obtaining a low-frequency and high-frequency amplitude salient point, a low-frequency and high-frequency attenuation end point and low-frequency Gaussian distribution of the low-frequency signal, obtaining a second time domain information difference and a second amplitude difference of the noise signal point at a corresponding signal point in the low-frequency signal, and obtaining a low-frequency correction reference index according to the second amplitude difference and the second time domain information difference; if the low-frequency correction reference index is larger than the high-frequency correction reference index, taking the amplitude of the corresponding signal point in the low-frequency signal as the amplitude of the noise signal point in the high-frequency signal to obtain a modulation signal; and transmitting the modulation signal to a receiving end.
2. The method for transmitting digital information for an electronically controlled single cylinder diesel engine according to claim 1, wherein said obtaining a cylinder vibration signal from a single cylinder diesel engine intake valve seating process to a cylinder combustion explosion process comprises:
obtaining a complete cylinder body vibration signal and a cylinder pressure signal in the complete combustion and explosion process of the diesel engine; and acquiring a time period from the seating process of the intake valve to the combustion and explosion process of the cylinder by using the in-cylinder pressure signal, and intercepting the vibration signal of the complete cylinder body according to the time period to acquire the vibration signal of the cylinder body.
3. The method for transmitting digital information for an electronically controlled single cylinder diesel engine according to claim 1, wherein said decomposing the cylinder vibration signal into a low frequency signal and a high frequency signal comprises:
and processing the cylinder body vibration signal by utilizing wavelet transformation to obtain the low-frequency signal and the high-frequency signal.
4. The method of claim 1, wherein the method of filtering the noise signal points using the standard vibration attenuation constraints comprises:
sequentially carrying out a detection process on each signal point of the high-frequency signal by using the first constraint condition, the second constraint condition and the third constraint condition; the detection process detects the signal points of the high-frequency signal one by one in a time domain;
if an abnormal signal point is detected in the detection process, recording the position of the abnormal signal point and skipping the abnormal signal point to continue executing the detection process;
if a continuous preset number of abnormal signal points appear, considering the continuous abnormal signal points as the normal signal points; otherwise, the abnormal signal point is considered as the noise signal point.
5. The method for transmitting digital information for an electronically controlled single cylinder diesel engine according to claim 1, wherein said obtaining a high frequency correction reference index according to the first amplitude difference and the first time domain information difference comprises:
obtaining the high-frequency correction reference index by using a high-frequency correction reference index formula, wherein the high-frequency correction reference index formula comprises the following components:
wherein，
For the purpose of correcting the reference index for the high frequency,
is a natural constant and is a natural constant,
is as follows
Time domain information of each of said noise signal points,
time domain information of the high frequency amplitude bump point,
is as follows
The amplitude of each of said noise signal points,
is as follows
The standard amplitude corresponding to each noise signal point in the high-frequency Gaussian distribution;
obtaining a low-frequency correction reference index by using a low-frequency correction reference index formula, wherein the low-frequency correction reference index formula comprises:
wherein the content of the first and second substances,
the reference indicator is corrected for the low frequencies,
is a natural constant and is a natural constant,
is as follows
Time domain information of each of said noise signal points,
is the time domain information of the low-frequency high-frequency amplitude salient point,
is the amplitude of the corresponding signal point of the noise signal point in the low frequency signal,
the standard amplitude values corresponding to the corresponding signal points in the low-frequency Gaussian distribution are obtained.
6. The method according to claim 1, wherein the transmitting the modulated signal to a receiving end comprises:
sampling on the modulation signal by using a preset initial number of sampling points, carrying out binary coding transmission, and transmitting to a signal receiving end to obtain a received signal; taking the length ratio of the modulation signal to the receiving signal as a compression ratio; obtaining the ratio of the amplitude of each signal point of the modulation signal to the amplitude of each signal point of the receiving signal, and taking the average ratio as a distortion rate; weighting and summing the compression rate and the distortion rate to obtain an encoding error index; and if the coding error index is larger than a preset index threshold value, increasing the number of the sampling points until the coding error index is not larger than the index threshold value.
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