JP6534101B2 - Method and system for non-contact evaluation of rheological properties - Google Patents

Description

  The present invention relates to a method of evaluating rheological properties, and more particularly to a method of evaluating rheological properties using airborne ultrasound.

  Since a strong correlation is recognized between the hardness of fruits and vegetables and their ripeness, it has been practiced to measure the hardness of fruits and vegetables as a standard for determining the harvest time of fruits and vegetables. . However, when hardness is measured using a conventional needle-type hardness meter, since fruits and vegetables are damaged by the needles, there is a problem that the commercial value decreases.

  In this respect, Non-Patent Document 1 discharges compressed air onto the surface of fruits and vegetables, and measures the degree of depression (about several tens of μm) of the surface at that time as displacement of the position with a laser displacement sensor. Disclose a method of obtaining hardness information of the kind.

  On the other hand, in Non-Patent Document 1, from the viewpoint of measurement error, it is desirable to increase the compressed air pressure as much as possible to increase the displacement amount, but when measurement is performed with compressed air pressure too high erroneously causes plastic deformation in the measurement object Suggest that there is a risk of

Inuzuka Hiroshi et al., "Agricultural Electrification", May 2012, Vol. 65, No. 3, p8-11

  The present invention has been made in view of the problems in the prior art, and an object thereof is to provide a novel method for non-contact and non-invasive evaluation of the rheological properties of an object.

  As a result of intensive studies on a novel method for non-contact and non-invasive evaluation of the rheological properties of an object, the present inventor has arrived at the following constitution and reached the present invention.

  That is, according to the present invention, there is provided a method for non-contact evaluation of rheological properties of an object to be measured, comprising the steps of focusing air ultrasonic waves on the surface of the object to be measured; Measuring, acquiring a frequency spectrum of the time change of the vibration velocity, generating a first feature based on a bandwidth of a peak corresponding to a maximum vibration velocity of the frequency spectrum, and the vibration Acquiring an envelope of temporal change of displacement of the surface calculated from temporal change of velocity; generating a second feature based on a width of a peak corresponding to the maximum displacement of the envelope; Generating evaluation information for evaluating the rheological characteristic of the object to be measured based on a first feature amount and the second feature amount. That.

  As mentioned above, the present invention provides a novel method for non-contact and non-invasive evaluation of the rheological properties of objects.

The system configuration figure of the fruits and vegetables maturity evaluation system of this embodiment. The flowchart of the process which the fruit and vegetables maturity evaluation system of this embodiment performs. The figure for demonstrating the production | generation process of a 1st feature-value. The figure for demonstrating the production | generation process of 2nd feature value. The figure which shows the two-dimensional scatter chart as evaluation information. The figure for demonstrating the measuring method using pulse wave oscillation. The figure which shows an experimental result.

  The present invention provides a method for non-contact and non-invasive evaluation of the rheological properties of the object to be measured and a system for carrying out the method. The present invention does not limit the object to be measured, and can be applied not only to rheological properties but also to evaluation of any state strongly correlated with rheological properties. In the following, exclusively as a preferred application of the present invention, a method for contactlessly and noninvasively assessing the ripeness of fruits and vegetables (a strong correlation between the ripeness and the rheological properties of fruits and vegetables) Describe the system.

  Hereinafter, the present invention will be described with the embodiment shown in the drawings, but the present invention is not limited to the embodiments shown in the drawings. In the drawings referred to below, the same reference numerals are used for the common elements, and the description thereof will be omitted as appropriate.

  FIG. 1: shows typically the system configuration | structure of the fruit vegetables ripeness evaluation system 100 which is embodiment of this invention. The fruits and vegetables ripeness evaluation system 100 of this embodiment is a system for evaluating the degree of ripeness of fruits and vegetables (including fruits and vegetables which are edible for fruits). It comprises a reflecting mirror 12 for focusing the oscillated airborne ultrasound, a laser Doppler vibrometer 14 (hereinafter referred to as an LDV 14), and a computer 20.

  In the present embodiment, the planar vibrator 10 is fixed to the reflecting mirror 12 through a jig (not shown) in such a manner that its vibration surface is directed to the opening of the reflecting mirror 12. The planar vibrator 10 is fixed to the outside of the opening of the reflecting mirror 12 in the mode shown in FIG. 1 and based on the burst signal of the sine wave amplified by the amplifier 16, the aerial ultrasonic wave (plane wave) in the vertical direction of the vibration plane Oscillate. On the other hand, in the present embodiment, the reflecting mirror 12 has the same shape as that of the offset type parabona antenna, and is shown in FIG. 1 after the air ultrasonic wave oscillated from the planar vibrator 10 is reflected to the reflecting mirror 12. Thus, the flat vibrator 10 and the reflecting mirror 12 are positioned so as to be focused inside the opening of the reflecting mirror 12.

  In the present embodiment, in evaluating the ripeness of the vegetables 30, the positional relationship between the vegetables 30 and the reflecting mirror 12 is set so that the aerial ultrasonic waves oscillated from the planar vibrator 10 converge on the surfaces of the vegetables 30. After being fixed, the planar vibrator 10 is driven by the burst signal. At this time, the acoustic radiation force of focused air ultrasonic waves acts on the surface of the vegetables 30 to produce a very small displacement on the surface of the vegetables 30.

  In the present embodiment, the displacement response of the surface of the fruit vegetables 30 to the acoustic radiation force of the air ultrasonic waves is optically measured using the LDV 14. In the present embodiment, for this purpose, the through hole 13 for passing the laser beam emitted from the LDV 14 is formed in the reflecting mirror 12, and the laser beam emitted from the LDV 14 passes through the through hole 13 to The LDV 14 and the reflecting mirror 12 are positioned such that they enter the surface and the reflected light again enters the light receiving part of the LDV 14 through the through holes 13.

  The inner diameter of the through hole 13 is preferably about half the wavelength of the laser beam of the LDV 14. Further, in the low pass filter of the LDV 14, it is desirable to set an appropriate cutoff frequency (for example, 5 kHz) so that the high frequency component of the planar vibrator 10 is removed and only the displacement signal is extracted.

  In the present embodiment, the output of the LDV 14 is input to the computer 20, and the computer 20 evaluates the evaluation information for evaluating the ripeness of the vegetables 30 based on the measurement value input from the LDV 14. Generate Specifically, the LDV 14 outputs the vibration velocity of the surface of the fruit vegetables 30 (the vibration velocity in the incident direction of the laser beam), and the computer 20 evaluates the ripeness of the fruit vegetables 30 based on the vibration velocity. Generate evaluation information for In addition, when the LDV 14 also has a function to convert the vibration velocity into displacement and output it, the computer 20 evaluates the ripeness of the vegetables 30 based on the vibration velocity and displacement input from the LDV 14. Evaluation information may be generated.

  Further, the computer 20 requests the function generator 15 (hereinafter referred to as “FG 15”) to generate an oscillation signal by specifying parameters (the frequency of the sine wave and the number of bursts) for oscillating the air ultrasonic wave. The FG 15 receiving the signal generates a burst signal based on the designated parameter and outputs it to the amplifier 16.

  The configuration of the fruit and vegetables ripeness evaluation system 100 has been described above. Subsequently, processing that the computer 20 receives and executes the measurement value input from the LDV 14 will be described based on the flowchart shown in FIG.

  In step 101, the frequency spectrum of the time change of the vibration velocity input from the LDV 14 is acquired. Specifically, first, the vibration velocity input from the LDV 14 is recorded over time for a predetermined period to obtain a temporal change of the vibration velocity. FIG. 3A shows the timing chart of the time change of the vibration velocity of the surface of the fruit and vegetable 30 obtained in step 101 and the burst signal applied to the planar vibrator 10 side by side. Subsequently, the frequency spectrum is acquired by performing Fourier transform on the time change of the acquired vibration velocity. FIG. 3 (b) shows the frequency spectrum of the temporal change in the vibration velocity of the surface of the fruit and vegetable 30 obtained in step 101. The frequency spectrum shown in FIG. 3B is a level expression with the maximum value of the vibration velocity as a reference value (0 dB).

  In the following step 102, among the one or more peaks (frequency components) constituting the frequency spectrum acquired in step 101, the bandwidth of the peak corresponding to the maximum vibration velocity (0 dB) is acquired. Specifically, after defining an appropriate vibration velocity level (dB) as a threshold, at a peak corresponding to the maximum vibration velocity (0 dB), a width between two points indicating the level of the vibration velocity equal to the threshold (frequency range )) As the peak bandwidth. In addition, the threshold value for acquiring the bandwidth of a peak experimentally calculates | requires appropriately a suitable value for every kind of fruit vegetables used as object.

  In the example shown in FIG. 3B, the threshold is defined as -10 dB, and at the peak corresponding to the maximum vibration velocity (0 dB), the width (frequency range) between two points at which the vibration velocity level indicates -10 dB It is acquired as width WF. While fruits and vegetables are immature, the peak corresponding to the maximum vibration velocity (0 dB) tends to be broad and the bandwidth WF tends to be large. On the other hand, as ripening of fruits and vegetables proceeds, the peak corresponding to the maximum vibration velocity (0 dB) tends to be sharp and the bandwidth WF tends to be smaller.

  In the following step 103, a first feature value is generated based on the bandwidth WF acquired in step 102. In the present embodiment, the bandwidth WF itself acquired in step 102 may be used as the first feature amount, but the bandwidth WF is divided by the center frequency fs of the frequency spectrum acquired in step 101 to be normal. It is preferable to use the converted value as the first feature value.

  In the following step 104, the temporal change of the vibration velocity of the surface of the fruit and vegetable 30 acquired in step 101 is integrated to obtain the temporal change of the displacement of the surface. However, when the LDV 14 has a function of outputting a displacement, the time change of the displacement may be acquired by recording the displacement input from the LDV 14 over time for a predetermined period in step 104. FIG. 4A shows a timing chart of the time change of the displacement of the surface of the fruits and vegetables 30 obtained in step 104 and the burst signal applied to the planar vibrator 10 side by side.

  In the following step 105, the envelope of the time change of the displacement of the surface of the fruits and vegetables 30 acquired in step 104 is acquired. Specifically, the displacement of the surface of the fruit and vegetable 30 acquired in step 104 is converted into an absolute value, and an envelope is acquired for the absolute value. The envelope can be obtained by a known method such as Hilbert transform. FIG. 4 (b) shows the envelope of the time variation of the displacement of the surface of the fruit and vegetable 30 obtained in step 105. The envelope shown in FIG. 4B is a level expression with the maximum value of displacement as a reference value (0 dB).

  In the following step 106, the width of the peak corresponding to the maximum displacement (0 dB) is acquired among the one or more peaks constituting the envelope acquired in step 105. Specifically, after defining an appropriate displacement level (dB) as a threshold, at the peak corresponding to the maximum displacement (0 dB), the width (time) between two points showing the level of displacement equal to the threshold is Get as a width. In addition, the threshold value for acquiring the width | variety of a peak calculates | requires an appropriate value beforehand for every kind of target fruit vegetables beforehand.

  In the example shown in FIG. 4B, the threshold is defined as -10 dB, and at the peak corresponding to the maximum displacement (0 dB), the width (time) between two points at which the displacement level indicates -10 dB is acquired as the width WT doing. When fruits and vegetables are immature, the displacement response is rapidly attenuated, so the peak corresponding to the maximum displacement (0 dB) tends to be sharp and the width WT becomes smaller. On the other hand, as the ripening of fruits and vegetables proceeds, the displacement response is less likely to be attenuated, so the peak corresponding to the maximum displacement (0 dB) tends to be broad and the width WT tends to be larger.

  In the following step 107, a second feature amount is generated based on the width WT acquired in step. In the present embodiment, the width WT acquired in step 106 may be used as the second feature amount, but the width WT is applied to the planar vibrator 10 after the burst signal is applied to the surface of the fruit 30. It is preferable that a normalized value obtained by dividing by the time ts required for the vibration velocity of to reach the maximum value be the second feature value.

  In this embodiment, the execution order of the series of processes (S101 to 103) for generating the first feature quantity and the series of processes (S104 to 107) for generating the second feature quantity are It is not limited.

  Finally, in step 108, evaluation information for evaluating the ripeness of the vegetables 30 is generated based on the first feature amount generated in step 103 and the second feature amount generated in step 107. As evaluation information generated in step 108, the following modes can be exemplified.

(Evaluation value of maturity)
In the present embodiment, an evaluation value of the degree of maturity can be generated as the evaluation information for evaluating the degree of ripeness.

  In this case, qualitative evaluation of the first and second characteristic quantities and the degree of ripening in the growth process of the fruits and vegetables to be evaluated in advance (eg, immature, slightly immature, moderately ripe, slightly overripe, excess) A multivariate that collects statistical information related to the five stages of ripening, uses the statistical information as a target variable, and uses two feature quantities (first and second feature quantities) as explanatory variables. Analysis is performed to generate a regression model representing the relationship between the degree of maturity and two feature quantities (first and second feature quantities). Then, in step 108, the first feature amount generated in step 103 and the second feature amount generated in step 107 are input to the regression model prepared in advance, so that the ripeness of the vegetables 30 can be increased. Derivation of evaluation value (immature, slightly immature, moderate ripeness, somewhat hyper ripe, hyper ripe).

(2D scatter plot)
In the present embodiment, as the evaluation information for evaluating the degree of maturity, it is possible to generate a two-dimensional scatter diagram having the first feature amount and the second feature amount as elements.

  Also in this case, similarly, regarding the fruits and vegetables to be evaluated in advance, qualitative evaluation of the first and second characteristic quantities and the degree of ripening in the growth process (for example, immature, slightly immature, suitable ripeness, slightly excessive) Statistical information related to five stages of ripeness / hypermaturation evaluation is collected, and based on the statistical information, a map of maturity is created on a two-dimensional scattergram as illustrated in FIG. 5 (a). .

  FIG. 5A shows a map of the degree of maturity in which the first feature quantity [WF / fs] is taken on the vertical axis and the second feature quantity [WT / ts] is taken on the horizontal axis. In the example shown in FIG. 6 (a), ranges corresponding to each of the five stages of maturity are developed on a two-dimensional scatter chart.

  Then, in step 108, the first feature amount [WF / fs] generated in step 103 and the second generated in step 107 are generated on the map of the degree of maturity (two-dimensional scatter diagram) prepared in advance. Draw a plot with the feature quantity [WF / fs] of 2 as an element. FIG. 5 (b) shows a two-dimensional scatter plot in which the plot is drawn at step 108. According to this method, it is possible to visually grasp the transition of the ripeness of the fruits and vegetables 30.

  The computer 20 displays the evaluation information generated in the above-described procedure on the display 22 and stores the evaluation information in the storage device 24.

  As mentioned above, although the fruit vegetables ripeness evaluation system 100 of this embodiment was demonstrated, the fruit vegetables ripeness evaluation system 100 has the following advantages.

  First of all, in the method of using the compressed air of Non-Patent Document 1 described above, displacement of several tens of μm is generated on the surface of fruits and vegetables each time of measurement, but in this system, There is an advantage that only slight displacement of about several tens to about 100 nm is generated on the surface of fruits and vegetables due to the use of the acoustic radiation force of air ultrasonic waves. Therefore, in this system, it is feared that the fruits and vegetables may be plastically deformed. However, even for delicate fruits and vegetables (eg, peaches) whose surface is easily deformed, it is possible to safely evaluate the ripeness.

  Second, compared to the compressed air of Non-Patent Document 1 described above, the aerial ultrasonic waves used by the present system have an advantage that their controllability is much higher. Depending on the type, optimize the oscillation parameters (sine wave frequency and burst number) of air ultrasonic waves, or force the fruits and vegetables by continuously oscillating air ultrasonic pulse waves at the resonance frequency of the target fruits and vegetables. Since it becomes possible to excite, a more accurate evaluation can be expected.

  In the embodiment described above, an example is shown in which the displacement of the surface of the measurement object is measured by the laser Doppler vibrometer, but the measurement may be performed using a laser displacement meter smaller and cheaper than the laser Doppler vibrometer. . In this case, as shown in FIG. 6A, the pulse wave of the air ultrasonic wave is continuously oscillated while changing the pulse interval T (frequency 1 / T), and the displacement of the surface of the object to be measured is Measure with a displacement gauge. In this way, as shown in FIG. 6B, since the frequency spectrum of displacement is obtained, the above-mentioned feature amount is detected even from the measurement value of the laser displacement meter whose detection accuracy is slightly lower than that of the laser Doppler vibrometer. It becomes possible.

  In addition, when mounting the fruit vegetables ripeness evaluation system 100 of this embodiment, you may integrate all the components shown in FIG. 1 in one housing, or the components shown in FIG. 1 are appropriate. It may be divided in units of When the fruit and vegetables maturity evaluation system 100 is divided into two or more constituent units, each constituent unit may be connected by wire or wireless, or some of the functions of the computer 20 and the functions of the storage device 24 may be connected. It may be arranged on a network such as the Internet.

  Moreover, although the example which uses the planar vibrator 10 and the reflecting mirror 12 as a means to make an acoustic radiation force act on the surface of fruits and vegetables in FIG. 1 was shown, the ultrasonic phased array search is carried out in other embodiments. You may use a child. When an ultrasonic phased array searcher is used, the drive timing of each transducer is controlled so that the airborne ultrasonic waves converge at one point, and, for example, a through hole is provided in the center of the ultrasonic phased array searcher. The laser beam emitted from the LDV 14 may be configured to be incident on the surface of the fruits and vegetables through the through hole.

  Although the present invention has been described above based on the embodiments of the method and system for non-contact and non-invasive evaluation of the ripeness of fruits and vegetables, the present invention limits the evaluation object to fruits and vegetables. As described above, the present invention provides a method and system for non-contact and non-invasive evaluation of the rheological property to be measured and any condition strongly correlated with the rheological property. Examples of applications other than the evaluation of ripeness of fruits and vegetables include methods and systems for non-contact and non-invasive evaluation of rheological properties of human skin (skin). In this case, statistical information pertaining to the first and second characteristic quantities and evaluation values of rheological properties (for example, skin age) is collected in advance for human skin (skin), and the statistical information is used. The skin age and the two feature quantities (first and second feature quantities) are subjected to multivariate analysis using the skin age as a target variable and the two feature quantities (first and second feature quantities) as explanatory variables. For example, a regression model representing the relationship of

  Although the present invention has been described above by way of the embodiments, the present invention is not limited to the above-described embodiments, and the functions and effects of the present invention can be included within the scope of other embodiments that can be conceived by those skilled in the art. As long as it plays, it is included in the scope of the present invention.

  Hereinafter, the present invention will be more specifically described using examples, but the present invention is not limited to the examples described later.

(Construction of system)
The system shown in Fig. 1 was constructed using parabolic reflectors manufactured by air ultrasonic transducers (NCG100-D50, Ul-tran, center frequency 100 kHz, aperture diameter 50 mm) and 3D printer (agilista-3100, Keyence) did. The parabolic reflector was provided with a cylindrical hole of 3 mm in diameter as a laser window for displacement detection. In addition, as a result of the sound wave propagation analysis in two dimensions, since the focal point of the ultrasonic wave was shifted to several mm in front, the laser window was shifted to a position 2.5 mm in front of the focus. In addition, the vibrator is fixed so that the reflecting direction of the ultrasonic wave and the incident direction of the laser light become constant.

(Experiment using fruits)
As samples, grapefruit, peach, grape, apple, and kiwi were cut into several cm and prepared, and fruits were arranged so that the focus position of focused ultrasound was on the surface of the fruit. From the function generator, a sine wave (100 kHz) burst signal was generated, and the output of the amplifier was adjusted to be about 100 Vpp. The experiment was conducted with the number of bursts of burst signal being 100 for grapefruit and peach, and the number of bursts of burst signal being 160 for grape, apple and kiwi.

  The vibration velocity was detected by a laser Doppler vibrometer (AT500, Graphtec), and a vibration waveform was acquired at a sampling frequency of 625 kHz using an oscilloscope. In order to remove the high frequency vibration component of the ultrasonic transducer and extract only the displacement signal due to compression, the LPF of the vibrometer was set to 5 kHz and the HPF was set to DC. Also, the vibration response was integrated to calculate the displacement response.

  Further, as samples, apples, oranges and mandarin oranges were prepared, and experiments were conducted in the same manner as described above. The same experiment was performed twice for each sample, with a period of one week.

(Experimental result)
The first feature [WF / fs] and the second feature [WF / fs] were obtained for each of five types of samples (grapefruit, peach, grape, apple, kiwi). The threshold values for acquiring the two feature quantities were both set to -10 dB. FIG. 7A shows an experiment of five types of samples in a two-dimensional scatter diagram in which the first feature quantity [WF / fs] is taken on the vertical axis and the second feature quantity [WT / ts] is taken on the horizontal axis. It is the figure which plotted the result.

  The first feature quantity [WF / fs] was acquired for each of three types of samples (apple, orange, and mandarin orange). FIG. 7 (b) shows the time change of the first feature quantity [WF / fs] of each sample. As shown in FIG. 7 (b), the first feature quantity [WF / fs] decreased with the passage of time for all three types of samples.

DESCRIPTION OF SYMBOLS 10 Planar vibrator 12 Reflector 13 Through hole 14 Laser Doppler vibrometer 15 Function generator 16 Amp 20 Computer 22 Display 24 Storage device 30 Fruits and vegetables 100 Fruits and vegetables maturity evaluation system

Claims (10)

A method for contactlessly evaluating the rheological properties of an object to be measured, comprising
Focusing the airborne ultrasound on the surface to be measured;
Optically measuring the time variation of the vibration velocity of the surface;
Acquiring a frequency spectrum of the time change of the vibration velocity;
Generating a first feature based on the bandwidth of the peak corresponding to the maximum oscillation velocity of the frequency spectrum;
Acquiring an envelope of the time change of the displacement of the surface calculated from the time change of the vibration velocity;
Generating a second feature based on the width of the peak corresponding to the maximum displacement of the envelope;
Generating evaluation information for evaluating a rheological characteristic of the object to be measured based on the first feature amount and the second feature amount;
Method, including. The airborne ultrasound is oscillated from a transducer driven by a burst signal,
The first feature amount is
It is a value obtained by dividing the bandwidth of the peak corresponding to the maximum vibration velocity by the center frequency of the frequency spectrum,
The second feature value is
The width of the peak corresponding to the maximum displacement is a value obtained by dividing by the time required for the vibration velocity to reach the maximum value after the burst signal is applied to the vibrator.
The method of claim 1. The step of generating the evaluation information includes
Deriving the rheological characteristics based on a regression model prepared in advance using the evaluation value of the rheological characteristics as an objective variable and the first feature amount and the second feature amount as explanatory variables.
The method of claim 1 or 2. The step of generating the evaluation information includes
In the step of drawing a plot having the generated first feature amount and the second feature amount as an element with respect to the two-dimensional scattergram of the first feature amount and the second feature amount prepared in advance is there,
The method of claim 1 or 2. It is an evaluation system which evaluates the rheological property of the measuring object in a noncontact manner,
Means for focusing airborne ultrasound on the surface to be measured;
A means for optically measuring the time change of the vibration velocity of the surface;
Means for acquiring a frequency spectrum of the time change of the vibration velocity;
Means for generating a first feature based on the bandwidth of the peak corresponding to the maximum vibration velocity of the frequency spectrum;
A means for acquiring an envelope of the time change of the displacement of the surface calculated from the time change of the vibration velocity;
Means for generating a second feature based on the width of a peak corresponding to the maximum displacement of the envelope;
Means for generating evaluation information for evaluating the rheological property of the object to be measured based on the first feature amount and the second feature amount;
Evaluation system, including: The means for optically measuring is a laser Doppler vibrometer,
The evaluation system according to claim 5. The means for focusing airborne ultrasound on the surface of the object to be measured is
A reflecting mirror having a shape similar to that of an offset-type parabolic antenna, and a planar vibrator fixed to the outside of the opening so that its oscillation surface is directed to the opening of the reflecting mirror,
The planar oscillator and the reflecting mirror are positioned such that air ultrasonic waves oscillated from the planar oscillator are reflected by the reflecting mirror and focused inside the aperture of the reflecting mirror.
The reflecting mirror is formed with a through hole for passing the laser beam emitted from the laser doppler vibrometer, and the laser beam is positioned so as to be incident on the surface of the object to be measured through the through hole. Yes,
The evaluation system according to claim 6.   The evaluation system according to claim 7, wherein the means for focusing the airborne ultrasound on the surface to be measured is an ultrasonic phased array searcher. It is a method of evaluating the ripeness of fruits and vegetables without contact,
Focusing the airborne ultrasound on the surface of the fruits and vegetables;
Optically measuring the time variation of the vibration velocity of the surface;
Acquiring a frequency spectrum of the time change of the vibration velocity;
Generating a first feature based on the bandwidth of the peak corresponding to the maximum oscillation velocity of the frequency spectrum;
Obtaining an envelope of the time change of the displacement of the surface calculated from the time change of the vibration velocity;
Generating a second feature based on the width of the peak corresponding to the maximum displacement of the envelope;
Generating evaluation information for evaluating the ripeness of the fruits and vegetables based on the first feature amount and the second feature amount;
Method, including. A system for non-contact assessment of the ripeness of fruits and vegetables,
Means for focusing the airborne ultrasound on the surface of the fruits and vegetables;
A means for optically measuring the time change of the vibration velocity of the surface;
Means for acquiring a frequency spectrum of the time change of the vibration velocity;
Means for generating a first feature based on the bandwidth of the peak corresponding to the maximum vibration velocity of the frequency spectrum;
A means for acquiring an envelope of the time change of the displacement of the surface calculated from the time change of the vibration velocity;
Means for generating a second feature based on the width of a peak corresponding to the maximum displacement of the envelope;
Means for generating evaluation information for evaluating the ripeness of the fruit and vegetables based on the first feature amount and the second feature amount;
Fruit and vegetables maturity evaluation system.