CN115171719A - System, method and computer equipment for determining drift frequency of low-speed prompt tone of electric automobile - Google Patents
System, method and computer equipment for determining drift frequency of low-speed prompt tone of electric automobile Download PDFInfo
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Abstract
A system, a method and computer equipment for determining the drift frequency of a low-speed prompt tone of an electric automobile belong to the technical field of active sounding and solve the problem of low accuracy of acquiring the drift frequency in the prior art. The system of the present invention comprises: the device comprises an electric automobile working condition testing module, a constant speed working condition module, a uniform acceleration working condition module and a drift frequency determining module; the electric automobile working condition testing module is used for placing an electric automobile in the silencing chamber and arranging the microphone around the electric automobile; the uniform speed sound module comprises a uniform speed sound acquisition unit and a uniform speed sound signal processing unit; the uniform acceleration working condition module comprises a uniform acceleration sound acquisition unit and a uniform acceleration sound signal processing unit; the drift frequency determining module is used for determining the drift frequency of the low-speed prompt tone of the electric automobile according to the average self-power spectrum and the sound spectrum. The method is suitable for testing and analyzing the low-speed prompt tone of the electric automobile.
Description
Technical Field
The application relates to the field of active sounding of electric automobiles, in particular to a system, a method and computer equipment for determining drift frequency of low-speed prompt tone of an electric automobile.
Background
When an electric automobile (a pure electric automobile, a hybrid electric automobile, a fuel cell automobile and the like) runs at a low speed in a pure electric mode, the average external noise of the automobile is obviously reduced compared with that of a traditional internal combustion engine vehicle, so that other users on roads, including pedestrians, bicycles and the like, especially blind people and people with visual disorder are not easy to perceive the approach of the automobile, and traffic accidents are easily caused.
The electric vehicle low-speed prompt tone (GB/T37153-2018) specifies the vehicle speed range, the sound level limit value, the frequency requirement, the sound type, the requirements of a pause switch and the like and a test method for the operation of the electric vehicle low-speed running prompt tone (hereinafter referred to as the prompt tone). The standard applies to M 1 And N 1 Such as pure electric vehicles, hybrid electric vehicles having a pure electric drive mode, and fuel cell electric vehicles.
At present, the national standard GB/T37153-2018 'electric vehicle low-speed prompt tone' requires to test the frequency shift of the electric vehicle low-speed prompt tone and calculate the frequency shift rate changing along with the vehicle speed, and the national standard specifies a method for testing and calculating the frequency shift rate, so that the method is a method commonly used in the industry. The specific steps for determining the drift frequency are as follows:
(1) As shown in FIGS. 1-4, the sound signals at constant speeds of 5km/h, 10km/h, 15km/h, and 20km/h were measured.
(2) The average self-power spectrum of the sound signal at each speed is calculated respectively.
(3) A certain frequency peak is determined on the self-power spectrum of the sound signal corresponding to a speed of 5 km/h.
(4) And finding out frequency values corresponding to the frequency peaks on the self-power spectrums of 10km/h, 15km/h and 20km/h respectively by a visual comparison method.
The method has the disadvantages that when the sound frequency is complex, and a plurality of different peak values appear on the self-power spectrum, the peak values can interfere with each other, and at the moment, the frequency peak values under different vehicle speeds are difficult to accurately correspond by the self-power spectrum comparison method, so that the frequency peak value selection is wrong, further the frequency shift rate calculation result is wrong, pedestrian prompt tones which do not accord with the national standard are misjudged to accord with the standard, or pedestrian prompt tones which accord with the national standard are misjudged to accord with the national standard, namely the judgment is wrong.
The investment and the output of each automobile manufacturer in the field of electric automobiles are increasing, in order to avoid misjudgment of the frequency shift of the prompt tone of low-speed pedestrians, the accuracy of identifying the drift frequency is very necessary to be improved, and even the accuracy can reach one hundred percent. The method for visually comparing the average power spectrum in the process of determining the drift frequency in the prior art has the defects of being very non-intuitive, being difficult to determine the drift frequency correctly when a plurality of peak values interfere with each other, leading the prompt tone of the electric automobile to be not in accordance with the requirements of regulations once errors occur, inevitably increasing the possibility of causing accidents, further leading the irreparable cost if the accidents occur, and having serious consequences, so that the method is very necessary for improving the early warning accuracy of the prompt tone of the electric automobile under the low-speed working condition, and the key of the prompt tone is the drift frequency, so that how to obtain the high-precision determined drift frequency of the low-speed prompt tone of the electric automobile is a technical problem to be solved urgently.
Disclosure of Invention
The invention aims to solve the problem of low accuracy of acquiring a drift frequency in the prior art, and provides a system, a method and computer equipment for determining the drift frequency of a low-speed prompt tone of an electric automobile.
The invention is realized by the following technical scheme, and on one hand, the invention provides a system for determining the drift frequency of a low-speed prompt tone of an electric automobile, which comprises: the device comprises an electric automobile working condition testing module, a constant speed working condition module, a uniform acceleration working condition module and a drift frequency determining module;
the electric automobile working condition testing module comprises a microphone and a silencing chamber, the silencing chamber is used for accommodating an electric automobile to be tested and the microphone,
the microphone is used for acquiring a sound signal generated by the electric automobile to be detected;
the constant speed working condition module comprises a constant speed sound acquisition unit and a constant speed sound signal processing unit;
the uniform speed sound acquisition unit is used for acquiring sound signals of the electric automobile under a uniform speed working condition;
the uniform speed sound signal processing unit is used for processing the sound signal of the electric automobile under the uniform speed working condition to obtain an average self-power spectrum;
the uniform acceleration working condition module comprises a uniform acceleration sound acquisition unit and a uniform acceleration sound signal processing unit;
the uniform acceleration sound acquisition unit is used for acquiring sound signals of the electric automobile under a uniform acceleration working condition;
the uniform acceleration sound signal processing unit is used for processing the sound signal of the electric automobile under a uniform acceleration working condition to obtain a sound spectrum;
the drift frequency determination module is used for determining the drift frequency of the electric automobile according to the average self-power spectrum and the sound spectrum.
Furthermore, the anechoic chamber is a semi-anechoic chamber, and the shortest distance between the front end of the wedge in the anechoic chamber and the electric automobile to be detected in the front, rear, left and right directions is greater than 1m.
Further, the microphone is arranged on the front end face of the electric automobile to be detected.
Further, the drift frequency determination module comprises a spectrum acquisition unit, a drift frequency preliminary determination unit and a drift frequency final determination unit;
the spectrum acquisition unit is used for receiving the average self-power spectrum and the sound spectrum sent by the uniform acceleration sound acquisition unit and the uniform acceleration sound signal processing unit;
the drift frequency preliminary determination unit is used for selecting an order line according to the sound spectrum;
determining a frequency initial value under a constant speed working condition according to the order line;
the drift frequency final determination unit is used for determining the drift frequency of the electric automobile according to the frequency initial value under the constant-speed working condition and the average self-power spectrum, and specifically comprises the following steps:
setting a range value, acquiring a highest peak point on the average self-power spectrum according to the frequency initial value under the constant speed working condition and the range value, and determining the highest peak point as the drift frequency of the electric automobile.
In a second aspect, the present invention provides a method for determining a drift frequency of a low-speed warning tone of an electric vehicle, the method comprising:
step 1, acquiring a sound signal of an electric automobile under a constant-speed working condition;
acquiring a sound signal of the electric automobile under a uniform acceleration working condition;
processing the sound signal of the electric automobile under the uniform acceleration working condition to obtain a sound spectrum;
and 3, determining the drift frequency of the electric automobile according to the average self-power spectrum and the sound spectrum.
Further, the step 3 specifically includes:
step 3.1, selecting order lines according to the sound spectrum;
step 3.2, determining a frequency initial value under a constant-speed working condition according to the order line;
step 3.3, determining the drift frequency of the electric automobile according to the frequency initial value under the constant-speed working condition and the average self-power spectrum, specifically:
setting a range value, acquiring a highest peak point on the average self-power spectrum according to the frequency initial value and the range value under the constant speed working condition, and determining the highest peak point as the drift frequency of the electric automobile.
Further, the step 3.1 specifically includes:
step 3.1.1, setting a sound pressure level threshold value;
and 3.1.2, selecting an order line of which the sound pressure level is greater than the sound pressure level threshold value according to the sound spectrum.
Further, the sound spectrum takes the vehicle speed as a vertical coordinate, the frequency as an abscissa, the frequency unit as Hz, and the gray scale represents the sound pressure level.
Further, the processing the sound signal under the constant speed working condition to obtain an average self-power spectrum specifically includes: and processing the sound signal under the constant speed working condition by using a Hanning window and at least 66.6 percent of overlapping average to obtain an average self-power spectrum.
In a third aspect, the present invention provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, and the processor executes the steps of the method for determining the drift frequency of the low-speed warning tone of the electric vehicle when the processor runs the computer program stored in the memory.
The invention has the beneficial effects that:
the invention provides a system and a method for determining the drift frequency of a low-speed prompt tone of an electric vehicle, which can determine the drift frequency of the low-speed prompt tone of the electric vehicle more quickly and accurately.
In the low-speed range of the electric vehicle, the sound spectrum is generated by testing the sound signal of the whole process of uniform acceleration of the vehicle, the drifting process of each frequency peak value can be tracked according to the order line on the sound spectrum, and the drifting frequency is determined by combining the average self-power spectrum of the constant-speed working condition.
Compared with the prior art, the method can more intuitively observe all the drifting frequencies, and the accuracy rate of identifying the drifting frequencies at all speeds can reach nearly 100 percent, thereby providing very powerful safety guarantee for the electric automobile running at low speed.
The method is suitable for testing and analyzing the low-speed prompt tone of the electric automobile.
Drawings
In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a plot of the self-power spectrum at a vehicle speed of 5km/h (frequency in abscissa, hz in ordinate, amplitude in dB (A));
FIG. 2 is a graph of the self-power spectrum (frequency in Hz on the abscissa and amplitude in dB (A) on the ordinate) at a vehicle speed of 10 km/h;
FIG. 3 is a self-power spectrum plot (frequency in Hz on the abscissa and amplitude in dB (A) on the ordinate) for a vehicle speed of 15 km/h;
FIG. 4 is a self-power spectrum plot (frequency in abscissa, hz, amplitude in ordinate, dB (A)) at a vehicle speed of 20 km/h;
FIG. 5 is a schematic diagram of an electric vehicle condition testing module according to the present invention;
FIG. 6 is a sound spectrum of the present invention for a uniform acceleration condition;
FIG. 7 is a diagram showing the accurate determination of the drift frequency of sound at 5km/h velocity from the sound spectrum to the self-power spectrum;
FIG. 8 is a diagram showing the accurate determination of the drift frequency of a sound at a speed of 10km/h from the sound spectrum to the self-power spectrum;
FIG. 9 is a diagram of the accurate determination of the drift frequency of a sound at a speed of 15km/h from the sound spectrum to the self-power spectrum;
FIG. 10 is a diagram showing the accurate determination of the drift frequency of a sound at a speed of 20km/h from the sound spectrum to the self-power spectrum;
FIG. 11 is a graph of the frequency corresponding to the highest peak determined on the self-power spectrum (frequency in abscissa, hz in ordinate, amplitude in dB (A));
FIG. 12 is a schematic flow chart of the method of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and intended to be illustrative of the present invention and are not to be construed as limiting the present invention.
The first embodiment is an embodiment of a system for determining the drift frequency of the low-speed warning tone of the electric vehicle according to the present invention.
The system comprises: the device comprises an electric automobile working condition testing module, a constant speed working condition module, a uniform acceleration working condition module and a drift frequency determining module;
fig. 5 is a schematic diagram of an electric vehicle working condition testing module according to the present invention, and as shown in fig. 5, the electric vehicle working condition testing module includes a microphone and a noise elimination chamber, an electric vehicle is placed in the noise elimination chamber, and the microphone is disposed around the electric vehicle;
the electric automobile working condition testing module comprises a microphone and a silencing chamber, the silencing chamber is used for accommodating an electric automobile to be tested and the microphone,
the microphone is used for acquiring a sound signal generated by the electric automobile to be detected;
the constant speed working condition module comprises a constant speed sound acquisition unit and a constant speed sound signal processing unit;
the uniform speed sound acquisition unit is used for acquiring sound signals of the electric automobile under a uniform speed working condition;
the uniform speed sound signal processing unit is used for processing the sound signal of the electric automobile under the uniform speed working condition to obtain an average self-power spectrum;
the uniform acceleration working condition module comprises a uniform acceleration sound acquisition unit and a uniform acceleration sound signal processing unit;
the uniform acceleration sound acquisition unit is used for acquiring sound signals of the electric automobile under a uniform acceleration working condition;
the uniform acceleration sound signal processing unit is used for processing the sound signal of the electric automobile under a uniform acceleration working condition to obtain a sound spectrum;
the drift frequency determining module is used for determining the drift frequency of the electric automobile according to the average self-power spectrum and the sound spectrum.
In the embodiment, the electric vehicle working condition testing module is designed for acquiring the sound signal data of the electric vehicle under each working condition, so that the sound signal can be effectively acquired, and accurate data basis is provided for the follow-up determination of the drift frequency.
The system of the embodiment can acquire the sound signal of the electric automobile under the constant-speed working condition, process the sound signal under the constant-speed working condition, record the continuous sound signal of the automobile in the whole acceleration process, and acquire the continuous sound frequency spectrum. The time or the vehicle speed (the uniform acceleration working condition, the time and the vehicle speed are corresponding) is taken as the ordinate, the frequency (Hz) is taken as the abscissa, the gray scale represents the sound pressure level, and the sound data in the uniform acceleration process is generated into a sound spectrum. Through the sound spectrum, continuous bright lines with larger sound pressure levels, namely order lines, can be found, and the order lines are generated due to peak frequency drift, so that the drift frequency at each vehicle speed can be roughly determined along the order lines;
then, according to the drift frequency roughly determined at each vehicle speed, a corresponding peak point is selected on the average self-power spectrum under the constant speed working condition, so that the accurate drift frequency can be obtained, and therefore the inaccuracy caused by the fact that a plurality of peaks exist on the average self-power spectrum and the real drift frequency cannot be accurately determined can be solved.
In a second embodiment, the present embodiment is further limited to the system for determining a drift frequency of a low speed warning sound of an electric vehicle according to the first embodiment, wherein the anechoic chamber is further limited,
the method specifically comprises the following steps:
the silencing chamber is a semi-silencing chamber, and the shortest distances between the front end of the wedge in the silencing chamber and the electric automobile to be detected in the front, rear, left and right directions are larger than 1m.
In the embodiment, specific designs of the silencing chamber are given, including the type of the silencing chamber, and the position of the electric automobile in the silencing chamber is designed.
The semi-anechoic chamber is selected as the anechoic chamber, and can provide a standard test environment according to the absorption and reflection principles in sound transmission, so that the influence of uncertainty of the sound test environment on the test result is eliminated, and the consistency of the test result is higher;
the shortest distance between the front end of the wedge in the anechoic chamber and the electric automobile in the front, rear, left and right directions is larger than 1m, and according to the absorption and reflection principle in sound transmission, an ideal free sound field environment can be obtained far away from the edge of the anechoic chamber, so that the consistency of a test result is higher;
the method can meet the requirement for collecting the sound signals of the electric automobile under the constant-speed working condition and the uniform acceleration working condition, and is used for identifying the drift frequency of the electric automobile in the follow-up process.
In a third embodiment, the present invention is further limited to the system for determining a drift frequency of a low speed warning sound of an electric vehicle according to the first embodiment, wherein the microphone is further limited,
the method specifically comprises the following steps:
the microphone is arranged on the front end face of the electric automobile to be detected.
In the embodiment, the position setting mode of the microphone is specifically as follows according to the requirements of the national standard GB/T37153-2018 "electric vehicle low speed prompt tone": the height of the front end face of the electric automobile to be detected is 1.2 meters, and the distance between the front end face and the central axis of the electric automobile to be detected is 2 meters.
This embodiment can realize effectively gathering the sound signal of electric automobile under the operating mode and the even acceleration operating mode of speeding, can avoid gathering unnecessary sound signal, reduces the adverse effect of noise factor promptly, and then improves the accuracy of the electric automobile's of final definite drift frequency, has improved the accuracy of entire system to the electric automobile frequency value.
In a fourth aspect, the present invention provides a system for determining a drift frequency of a low speed warning sound of an electric vehicle as defined in the first aspect, wherein the drift frequency determining means is further defined,
the method specifically comprises the following steps:
the drift frequency determination module comprises a spectrum acquisition unit, a drift frequency preliminary determination unit and a drift frequency final determination unit;
the spectrum acquisition unit is used for receiving the average self-power spectrum and the sound spectrum sent by the uniform acceleration sound acquisition unit and the uniform acceleration sound signal processing unit;
the drift frequency preliminary determining unit is used for selecting order lines according to the sound spectrum;
determining a frequency initial value under a constant speed working condition according to the order line;
the drift frequency final determination unit is used for determining the drift frequency of the electric automobile according to the frequency initial value under the constant-speed working condition and the average self-power spectrum, and specifically comprises the following steps:
setting a range value, acquiring a highest peak point on the average self-power spectrum according to the frequency initial value under the constant speed working condition and the range value, and determining the highest peak point as the drift frequency of the electric automobile.
It should be noted that, after the order line is determined, a frequency value under each constant speed working condition is determined on the order line and is recorded as a frequency initial value, a range value is set, such as ± 2Hz, a frequency value region (the frequency initial value is-2 Hz, and the frequency initial value is + -2 Hz) is obtained according to the frequency initial value and the range value, a highest peak point is found on an average self-power spectrum according to the frequency value region, and a frequency corresponding to the peak point is determined as an electric vehicle drift frequency, which is an accurate drift frequency.
In the embodiment, the specific structure and function of the drift frequency determination module are provided, wherein the drift frequency preliminary determination unit obtains the frequency initial value under the constant-speed working condition by selecting the order line, and can provide the basis for determining the drift frequency of the electric vehicle on the average self-power spectrum subsequently, so that the final determination of the drift frequency of the electric vehicle is accurate according to the basis, and the accuracy of the whole system on the frequency value of the electric vehicle is improved.
Fifth embodiment, an embodiment of the method for determining a drift frequency of a low speed warning tone of an electric vehicle according to the present invention is shown in fig. 12, which is a schematic flowchart of the method according to the present invention, and is shown in fig. 12.
The method comprises the following steps:
step 1, acquiring a sound signal of an electric automobile under a constant-speed working condition;
acquiring a sound signal of the electric automobile under a uniform acceleration working condition;
processing the sound signal of the electric automobile under the uniform acceleration working condition to obtain a sound spectrum;
and 3, determining the drift frequency of the electric automobile according to the average self-power spectrum and the sound spectrum.
In the embodiment, the sound signal of the electric automobile under the uniform speed working condition and the sound signal under the uniform acceleration working condition are firstly acquired, namely the sound signal under the uniform speed working condition is processed, the continuous sound signal of the automobile in the whole acceleration process is also recorded, and the continuous sound frequency spectrum can be acquired.
According to the drift frequency roughly determined at each vehicle speed, a corresponding peak point is selected on the average self-power spectrum under the constant-speed working condition, so that the accurate drift frequency can be obtained, and the inaccuracy caused by the fact that the average self-power spectrum has a plurality of peaks and the real drift frequency cannot be accurately determined can be solved.
Sixth, the present embodiment is further limited to the method for determining the drift frequency of the low speed warning tone of the electric vehicle according to fifth, wherein in the present embodiment, the step 3 is further limited,
the method specifically comprises the following steps:
step 3.1, selecting an order line according to the sound spectrum;
step 3.2, determining a frequency initial value under a constant-speed working condition according to the order line;
step 3.2 is the rough determination of the drift frequency;
step 3.3, determining the drift frequency of the electric automobile according to the initial frequency value under the constant speed working condition and the average self-power spectrum, specifically:
setting a range value, acquiring a highest peak point on the average self-power spectrum according to the frequency initial value under the constant speed working condition and the range value, and determining the highest peak point as the drift frequency of the electric automobile.
This step 3.3 is an accurate determination of the drift frequency.
In the embodiment in the market, the initial value of the frequency under the constant-speed working condition is determined according to the order line, and the initial value is very effective to the finally determined drift frequency of the electric automobile, so that the accuracy of the finally determined drift frequency of the electric automobile can reach nearly one hundred percent.
Seventh embodiment, the present embodiment is further limited to the method for determining the drift frequency of the low speed warning tone of the electric vehicle according to the sixth embodiment, and in the present embodiment, the step 3.1 is further limited,
the method specifically comprises the following steps:
step 3.1.1, setting a sound pressure level threshold;
and 3.1.2, selecting an order line of which the sound pressure level is greater than the sound pressure level threshold value according to the sound spectrum.
In the embodiment, a continuous bright line with a large sound pressure level, namely an order line, can be found through the sound spectrum, and the order line is generated due to the drift of the peak frequency, so that the drift frequency at each vehicle speed can be roughly determined along the order line, the accuracy of the finally determined drift frequency of the electric vehicle is further improved, and the accuracy of the method of the embodiment on the frequency value of the electric vehicle is improved.
In an eighth embodiment, the method for determining a drift frequency of a low speed warning sound of an electric vehicle according to the fifth embodiment is further defined, and in the fifth embodiment, the sound spectrum is further defined,
the method specifically comprises the following steps:
the sound spectrum takes the vehicle speed as a vertical coordinate, the frequency (Hz) as a horizontal coordinate, and the gray scale represents the sound pressure level.
In the embodiment, time or vehicle speed (a uniform acceleration working condition, time and vehicle speed are corresponding relations) is taken as a vertical coordinate, frequency (Hz) is taken as a horizontal coordinate, gray scale represents sound pressure level, sound data in the uniform acceleration process is generated into a sound spectrum, an accurate data relation and a data result of the frequency and the sound pressure level measured by the electric vehicle under the uniform acceleration working condition can be given, and then an initial value of the electric vehicle drift frequency can be determined according to the data relation and the result, so that an effective data basis is provided for an accurate frequency value to be determined finally.
Ninth, the present embodiment is further limited to the method for determining the drift frequency of the low speed warning tone of the electric vehicle described in the fifth embodiment, and in the present embodiment, the step of processing the sound signal under the constant speed condition to obtain the average self-power spectrum is further limited,
the method specifically comprises the following steps:
and processing the sound signal under the constant speed working condition by using a Hanning window and at least 66.6 percent of overlapping average to obtain an average self-power spectrum.
In the embodiment, the Hanning window is adopted according to the requirements of national standard GB/T37153-2018 'electric automobile low speed prompt tone'.
Tenth embodiment, the present embodiment is directed to a computer device for determining a drift frequency of a low speed warning tone of an electric vehicle, including a memory and a processor, where the memory stores a computer program, and the processor executes the steps of the method for determining a drift frequency of a low speed warning tone of an electric vehicle when the processor runs the computer program stored in the memory.
The embodiment has corresponding technical features with the method for determining the drift frequency of the low-speed warning tone of the electric vehicle, and therefore, the embodiment is not described in detail.
The present embodiment is directed to a specific example of the method for determining the drift frequency of the low speed warning tone of the electric vehicle described above.
The method specifically comprises the following steps:
(1) Vehicle preparation: the vehicle is positioned in the semi-silencing chamber with the rotary drum, and the shortest distances from the front, the back, the left and the right of the vehicle to the front end of the wedge in the silencing chamber are more than 1m.
(2) Microphone placement: the microphones are placed at positions P, P' on the front face of the vehicle as shown in fig. 5.
(3) Acquiring uniform working condition data: the vehicle is driven at constant speed of 5km/h, 10km/h, 15km/h and 20km/h respectively, and sound is collected by using a data collection device. At least 5s are collected per vehicle speed.
(4) Collecting data of uniform acceleration working conditions: make the vehicle keep the acceleration at 1m/s 2 The speed of the vehicle is accelerated from 0km/h to 20km/h, and the sound of the whole acceleration process is collected by using data collection equipment.
(5) Data processing:
(1) the vehicle speed is used as the ordinate, the frequency (Hz) is used as the abscissa, the gray scale represents the sound pressure level, and the sound data in the acceleration process is generated into a sound spectrum, as shown in fig. 6.
(2) And with the amplitude dB (A) as an ordinate and the frequency (Hz) as an abscissa, generating average self-power spectrums of sound signals running at the speeds of 5km/h, 10km/h, 15km/h and 20km/h respectively. The calculation process for data processing uses a hanning window and an at least 66.6% overlap average.
(6) Drift frequency rough determination: a straight line parallel to the abscissa is drawn at a speed of 5km/h on the ordinate, an obvious "order line" is selected on the "sound spectrum", and the frequency value corresponding to the abscissa of the intersection of the straight line and the selected "order line" is recorded and named f1'. In this way, along this selected "order line", the frequency values f2', f3', f4' at the corresponding speeds of 10km/h, 15km/h, 20km/h, respectively, are determined and recorded. As shown in fig. 6.
The results are reported as: f1'=368.64Hz, f2' =407.38Hz, f3'=453.49Hz, f4' =513.13Hz
(7) Accurately determining the drift frequency: finding the position of f1' =368.64Hz on the abscissa of the self-power spectrum of the sound when the vehicle speed is 5km/h, finding the highest peak point in the range of +/-2 Hz near the position, and recording the frequency f1=368.04 corresponding to the peak point, namely the accurate drift frequency, as shown in fig. 7 and fig. 11.
According to the method, peak points corresponding to f2', f3' and f4' are determined on the self-power spectrum of the sound with the vehicle speed of 10km/h, 15km/h and 20km/h respectively, and the peak points are accurate frequency values f2, f3 and f4.
As shown in fig. 7-10.
The determination result is: f1=368.04, f2=407.22, f3=453.85, f4=512.61
It should be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, various steps or methods may be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following technologies, which are well known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.
In the description of the specification, reference to the description of "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, but are not intended to indicate or imply that the device or element so referred to must have a particular orientation, be constructed in a particular orientation, and be operated in a particular manner, and are not to be construed as limiting the invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specified otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood according to specific situations by those of ordinary skill in the art.
In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
Although embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are exemplary and not to be construed as limiting the present invention, and that changes, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (10)
1. A system for determining a drift frequency of a low speed warning tone of an electric vehicle, the system comprising: the device comprises an electric automobile working condition testing module, a constant speed working condition module, a uniform acceleration working condition module and a drift frequency determining module;
the electric automobile working condition testing module comprises a microphone and a silencing chamber, the silencing chamber is used for accommodating the electric automobile to be tested and the microphone,
the microphone is used for acquiring a sound signal generated by the electric automobile to be detected;
the constant-speed working condition module comprises a constant-speed sound acquisition unit and a constant-speed sound signal processing unit;
the uniform speed sound acquisition unit is used for acquiring sound signals of the electric automobile under a uniform speed working condition;
the uniform speed sound signal processing unit is used for processing the sound signal of the electric automobile under the uniform speed working condition to obtain an average self-power spectrum;
the uniform acceleration working condition module comprises a uniform acceleration sound acquisition unit and a uniform acceleration sound signal processing unit;
the uniform acceleration sound acquisition unit is used for acquiring sound signals of the electric automobile under a uniform acceleration working condition;
the uniform acceleration sound signal processing unit is used for processing the sound signal of the electric automobile under a uniform acceleration working condition to obtain a sound spectrum;
the drift frequency determination module is used for determining the drift frequency of the electric automobile according to the average self-power spectrum and the sound spectrum.
2. The system for determining the drift frequency of the low-speed warning tone of the electric automobile according to claim 1, wherein the anechoic chamber is a semi-anechoic chamber, and the shortest distance between the front end of the wedge in the anechoic chamber and the electric automobile to be detected in the front, rear, left and right directions is greater than 1m.
3. The system for determining the drift frequency of the low-speed warning tone of the electric vehicle as claimed in claim 1, wherein the microphone is disposed on a front end face of the electric vehicle to be detected.
4. The system for determining the drift frequency of the low-speed prompt tone of the electric automobile according to claim 1, wherein the drift frequency determination module comprises a spectrum acquisition unit, a drift frequency preliminary determination unit and a drift frequency final determination unit;
the spectrum acquisition unit is used for receiving the average self-power spectrum and the sound spectrum sent by the uniform acceleration sound acquisition unit and the uniform acceleration sound signal processing unit;
the drift frequency preliminary determination unit is used for selecting an order line according to the sound spectrum;
determining a frequency initial value under a constant speed working condition according to the order line;
the drift frequency final determining unit is used for determining the drift frequency of the electric automobile according to the frequency initial value under the constant speed working condition and the average self-power spectrum, and specifically comprises the following steps:
setting a range value, acquiring a highest peak point on the average self-power spectrum according to the frequency initial value under the constant speed working condition and the range value, and determining the highest peak point as the drift frequency of the electric automobile.
5. A method for determining the drift frequency of a low-speed warning tone of an electric automobile is characterized by comprising the following steps:
step 1, acquiring a sound signal of an electric automobile under a constant-speed working condition;
acquiring a sound signal of the electric automobile under a uniform acceleration working condition;
step 2, processing the sound signal under the constant speed working condition to obtain an average self-power spectrum;
processing the sound signal of the electric automobile under the uniform acceleration working condition to obtain a sound spectrum;
and 3, determining the drift frequency of the electric automobile according to the average self-power spectrum and the sound spectrum.
6. The method for determining the drift frequency of the low-speed warning tone of the electric vehicle according to claim 5, wherein the step 3 specifically comprises:
step 3.1, selecting an order line according to the sound spectrum;
step 3.2, determining a frequency initial value under a constant-speed working condition according to the order line;
step 3.3, determining the drift frequency of the electric automobile according to the initial frequency value under the constant speed working condition and the average self-power spectrum, specifically:
setting a range value, acquiring a highest peak point on the average self-power spectrum according to the frequency initial value and the range value under the constant speed working condition, and determining the highest peak point as the drift frequency of the electric automobile.
7. The method for determining the drift frequency of the low-speed warning tone of the electric vehicle according to claim 6, wherein the step 3.1 specifically comprises:
step 3.1.1, setting a sound pressure level threshold;
and 3.1.2, selecting an order line of which the sound pressure level is greater than the sound pressure level threshold value according to the sound spectrum.
8. The method for determining the drift frequency of the low-speed warning tone of the electric automobile according to claim 5, wherein the sound spectrum takes the vehicle speed as an ordinate, the frequency as an abscissa, the frequency unit as Hz, and the gray scale represents the sound pressure level.
9. The method according to claim 5, wherein the processing the sound signal under the constant speed condition to obtain an average self-power spectrum comprises: and processing the sound signal under the constant speed working condition by using a Hanning window and at least 66.6 percent of overlapping average to obtain an average self-power spectrum.
10. A computer device comprising a memory and a processor, the memory having stored therein a computer program, characterized in that the steps of the method of any of claims 5 to 9 are performed when the processor runs the computer program stored by the memory.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210631146.0A CN115171719B (en) | 2022-06-06 | 2022-06-06 | System, method and computer equipment for determining drift frequency of low-speed prompt tone of electric automobile |
| PCT/CN2023/090296 WO2023236672A1 (en) | 2022-06-06 | 2023-04-24 | System and method for determining drift frequency of acoustic vehicle alerting system of electric vehicles running at low speed, and computer device |
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| CN202210631146.0A CN115171719B (en) | 2022-06-06 | 2022-06-06 | System, method and computer equipment for determining drift frequency of low-speed prompt tone of electric automobile |
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| CN115171719B CN115171719B (en) | 2024-05-07 |
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| WO2023236672A1 (en) * | 2022-06-06 | 2023-12-14 | 中国第一汽车股份有限公司 | System and method for determining drift frequency of acoustic vehicle alerting system of electric vehicles running at low speed, and computer device |
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| CN112298030A (en) * | 2020-10-16 | 2021-02-02 | 中国第一汽车股份有限公司 | Frequency response test system and method for low-speed prompt tone device of electric automobile |
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| WO2023236672A1 (en) | 2023-12-14 |
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