JP3802200B2 - Fruit ripeness measuring method and ripeness measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for measuring the degree of maturity of fruit and a method for measuring the degree of maturity (ripening) of a fruit that eats a fruit part (hereinafter referred to as a fruit), etc. The present invention relates to a degree measuring device.
[0002]
[Prior art]
Conventionally, the research result that the numerical value A calculated | required from a secondary resonant frequency and the weight of a fruit has a high correlation with the cram degree of a fruit has been obtained.
[0003]
This maturity measuring apparatus, for example, places a fruit on a vibration table of a shaker, vibrates with a sine wave, and continuously changes the vibration frequency, the speed of vibration appearing on the fruit surface or By measuring the change in acceleration, the secondary resonance frequency can be detected.
Further, the second resonance frequency of the fruit at that time may be detected by exciting with a sound wave of random noise by a speaker directed to the fruit.
[0004]
However, even if the fruit has a constant ripeness, the greater the mass, the lower the resonance frequency. Therefore, it is difficult to determine the ripeness unless the fruit mass is substantially constant only by the resonance frequency. Therefore, conventionally, the mass of each fruit is separately measured with a weigh scale or the like, and combined with the measurement result of the secondary resonance frequency, which is the basis for determining the maturity.
[0005]
FIG. 9 is a diagram illustrating an example of a conventional fruit maturity (hardness) determination system.
In the system of FIG. 9, the fruit 10 is placed on the shaker 30 via the mounting jig 31, and the fruit is changed by the laser Doppler vibrometer 33 via the sensor head 33 a while changing the excitation frequency by the shaker controller 32. A signal proportional to the surface vibration velocity v is taken out and analyzed by a frequency analyzer (FFT) 34 to obtain a secondary resonance frequency, and the result is displayed on the display 34 a of the FFT 34.
[0006]
FIG. 10 is a diagram illustrating an example of the display of a characteristic curve representing the transmission gain of the excitation force in the measured fruit. In the figure, the vertical axis is a numerical value (gain) represented by the magnification with respect to the excitation force F applied to the fruit of speed v, and the horizontal axis is the frequency when the excitation frequency is changed. _fr is the secondary resonance frequency.
The mass of the fruit is measured by another measuring device such as a weighing scale 35 before the fruit is placed on the vibrator 30, and the result is displayed on the display unit 35a of the weighing scale.
[0007]
The maturity is determined by inputting the secondary resonance frequency and the numerical value displayed on the display unit 35a of the weigh scale to the personal computer 36, and calculating the equation of the numerical value A described above by the previously input program. This is performed with reference to data (table) corresponding to the type of fruit to be determined. The result is displayed on the display unit 36 a of the personal computer 36.
[0008]
FIG. 11 shows the degree of correlation between a large number of objects to be judged with the value of the judgment value A calculated by a personal computer as the vertical axis and the hardness of the fruit to be judged actually measured by a destructive test as the horizontal axis. It is explanatory drawing which shows.
B in the figure is a maturity determination curve indicating the average value of each measurement point.
[0009]
In addition, the invention of Japanese Patent Laid-Open No. 7-35730 “Method for determining the maturity of fruit and the like by sound and vibration” strikes the fruit and the like with a striking body having an appropriate mass with respect to the mass of the fruit and the like. And the maturity is determined by a numerical value calculated from the resonance frequency and the mass of the fruit or the like.
In a specific embodiment, a size detector for obtaining a numerical value in place of mass, and a light hitting device and a vibration detector for obtaining a resonance frequency are shown.
[0010]
[Problems to be solved by the invention]
However, the maturity determination system of FIG. 9 measures the weight of the fruit with another measuring device such as a weigh scale before placing it on the vibrator. Therefore, in order to apply to the work at the time of shipping and sorting of fruits and vegetables, the weight of the fruit and the secondary resonance frequency must be separately measured with separate measuring instruments, so that the work efficiency is poor. There is.
The laser vibrometer is complicated and expensive. Moreover, it is difficult to align the optical axis of the laser beam with one point to be measured. Therefore, it is desirable to have a maturity measuring method and apparatus that can be easily measured by anyone with less expensive equipment if possible.
[0011]
On the other hand, the invention presented in Japanese Patent Application Laid-Open No. 7-35730 observes numerical values related to a part of the outer shape instead of measuring the weight of the fruit, but the outer shape of the fruit is always similar. Therefore, the size determination result lacks accuracy and sometimes produces a large error. In addition, the present invention needs to select an impacting body having an appropriate mass for each object such as a fruit. If the selection is made incorrectly, it is difficult to measure the resonance frequency or the appearance of the object to be judged is damaged. There is a risk of occurrence.
[0012]
An object of the present invention is to provide a fruit maturity measuring method and an apparatus therefor that are free from any risk of damage to an object to be measured, are inexpensive, and have high determination efficiency.
[0013]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention of claim 1 calculates the secondary resonance frequency of fruit and the weight of the fruit, and measures the maturity of the fruit based on the secondary resonance frequency and the weight. In the method for measuring the degree of ripeness of fruit to be obtained, information relating to the excitation force and information relating to the acceleration are obtained, the information relating to the acceleration is referred to, the fruit being vibrated is vibrated at a constant acceleration, and the acceleration A fruit ripeness measuring method, characterized in that the weight of the fruit is calculated based on information relating to the excitation force when is kept constant.
[0014]
Invention of Claim 2 is the fruit ripeness measuring apparatus which measures the ripeness of the said fruit based on the secondary resonance frequency of the fruit and the weight of the said fruit, The vibration means which vibrates the said fruit, Based on the acceleration information, the fruit vibrates at a constant acceleration based on the excitation force detection means for detecting the excitation force information of the excitation means, the acceleration detection means for detecting the acceleration information of the excitation means. As described above, the excitation force control means for controlling the excitation force of the excitation means, and the weight calculation means for obtaining the weight of the fruit based on the excitation force information in which the acceleration is kept constant. It is a ripeness measuring apparatus of the fruit characterized by providing.
[0015]
The invention of claim 3 is a fruit ripeness measuring method for obtaining a secondary resonance frequency of fruit and the weight of the fruit, and measuring the ripeness of the fruit based on the secondary resonance frequency and the weight. , Detecting information on the excitation force to the fruit and information on the acceleration of the portion of the fruit to be vibrated, and referring to the information on the acceleration so that the fruit being vibrated is vibrated at a constant acceleration. While shaking and changing the excitation frequency, a transfer function of the excitation force is obtained based on the information on the acceleration and the excitation force, and a secondary resonance frequency of the fruit is obtained from the transfer function. Is a method for measuring the maturity of a fruit.
[0016]
Invention of Claim 4 is the fruit ripeness measuring apparatus which determines the maturity of the said fruit based on the secondary resonance frequency of the fruit and the weight of the said fruit, The vibration means which gives a vibration to the said fruit, Excitation force detection means for detecting excitation force information of the excitation means, acceleration detection means inserted between the excitation means and the fruit, and detecting acceleration information of a portion to be excited, and the excitation Based on force information and acceleration information of the portion to be vibrated, frequency analysis means for performing frequency analysis, and based on the acceleration information, the vibration means is controlled so that the fruit vibrates at a constant acceleration, And, based on the analysis result of the frequency analysis means and the excitation force control means capable of continuously changing the excitation force, the transfer function characteristics of the excitation force between the excitation means and the fruit are obtained. Obtain the second resonance of the fruit from its transfer function characteristics A resonance frequency calculating means for calculating a wave number, a ripeness measurement apparatus of the fruit, characterized in that it comprises a.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings.
(First embodiment)
FIG. 1 is an explanatory diagram showing a functional system of each part of the first embodiment of the fruit ripeness measuring apparatus according to the present invention.
The fruit maturity measurement is performed based on the secondary resonance frequency and mass (weight) of the fruit. The fruit maturity measurement method of the first embodiment is a control unit (hereinafter referred to as an additional force) that controls the excitation force. The weight of the fruit is measured based only on the output of the vibrator 1 controlled by the vibration controller 2.
[0018]
When the target fruit 10 is placed on the vibrator 1 and vibrated, the vibration force required when the fruit 10 is present differs from that when the fruit 10 is absent. This is because the weight on the vibrator 1 is changed by placing the fruit 10 on the vibrator 1. Here, to vibrate at the same acceleration whether or not there is a fruit, it is necessary to change the excitation force, and by detecting the excitation current for increasing or decreasing this excitation force, The weight can be detected.
[0019]
The vibrator 1 of this embodiment includes a vibrator 1a and an acceleration sensor 1b, and can be controlled so as to always vibrate at a constant acceleration. Therefore, even if there is a fruit on the vibrator 1 Even without it, it can be vibrated at the same acceleration.
[0020]
In the vibrator 1, the output of the acceleration sensor 1 b is fed back to one terminal of the operational amplifier 2 a of the vibration controller 2 in order to keep the acceleration a constant. In addition, the vibrator 1 detects the excitation force F by flowing a supply current to the excitation unit 1a through the resistor R and taking out a potential difference between both ends of the resistor R.
The relationship between the excitation force and the weight is F = m · a, where F is the excitation force, m is the weight, and a is the acceleration. If the acceleration a is constant, the excitation force F is the weight m Is proportional to
In addition, 11 is an attachment jig for fixing the target fruit 10 to the movable part on the upper surface of the vibrator 1.
[0021]
In the first embodiment, the detection of the secondary resonance frequency of the fruit uses substantially the same means as in the system of FIG.
That is, first, the vibration speed of the surface of the fruit 10 being vibrated is detected by the Doppler effect using the sensor head 13 and is converted into an electric signal by the laser vibrometer 3 to be a frequency analyzer (hereinafter referred to as FFT) 4. Input to one of the terminals. The output of the acceleration sensor 1b built in the vibrator 1 is input to the other terminal of the FFT 4.
[0022]
The output of the FFT 4 is input to the maturity determination unit 5 to detect the secondary resonance frequency. Note that the output of the FFT 4 is also input to the other terminal of the operational amplifier 2a of the vibration controller 2, which is useful for setting the reference value of the vibration force.
[0023]
2-7 is a figure which shows an example of the frequency analysis result by FFT4.
2 to 7 are kiwis having substantially the same weight, and FIGS. 2 and 3, FIGS. 4 and 5, and FIGS. 6 and 7 are the same kiwis.
FIGS. 2 and 3 are for a normal standard maturity kiwi, FIGS. 4 and 5 are for a hard immature kiwi, and FIGS. 6 and 7 are soft and too mature. This is the case with Kiwi.
[0024]
2, 4, and 6 are curves in which the ratio between the vibration speed and the excitation force on the fruit surface is expressed as a gain, and the vertical axis is the vibration frequency.
3, 5, and 7 correspond to FIGS. 2, 4, and 6, respectively, and are curves in which the phase difference between the excitation force and the fruit surface vibration is the vertical axis, and the vibration frequency is the horizontal axis.
The frequencies f ₀ , f ₁ , and f _{2 at} the positions where the phase difference is 0 in FIGS. 3, 5, and 7 are the secondary resonance frequencies. The secondary resonance frequency f ₁ in the case of immaturity is higher than f _{0 in} the case of standard maturity, and the second resonance frequency f _{2 in} the case of being too mature is that in the case of standard maturity. lower than f _0.
[0025]
The maturity determination unit 5 detects the secondary resonance frequency as described above, and based on the acceleration a and the excitation force F output from the shaker 1 when vibrating at a low frequency, The weight m of is calculated. Then, based on the secondary resonance frequency and the weight m, for each kind of fruit created by data prepared in advance, refer to the relation table for each weight class and determine the maturity of the fruit. indicate.
[0026]
(Second Embodiment)
FIG. 8 is an explanatory diagram showing a functional system of each part of the second embodiment of the fruit ripeness measuring apparatus according to the present invention.
In the second embodiment, in order to detect the secondary resonance frequency of the target fruit, for example, a mechanical / electrical conversion element (hereinafter referred to as an impedance head) for measuring mechanical impedance, which is used as a force sensor, is used. ing.
[0027]
The laser vibrometer has high measurement accuracy but is expensive, and it takes time and effort to align the optical axis of light with one point on the surface of the object.
Therefore, in the second embodiment (maturity determination apparatus in FIG. 8), the impedance head 23 that outputs the excitation force F and the acceleration a is used as the vibrator 21 without using the laser vibrometer as in the first embodiment. It is attached, and the fruit 10 is placed on it and vibrated to measure the resonance frequency.
[0028]
In the case of a laser vibrometer, the speed of vibration transmitted to the opposite side of the fruit excitation point is detected, but if the fruit is vibrated, it can be shaken even with a small excitation force if the fruit is hard. However, if the fruit is soft, it will not shake to the same extent unless a large excitation force is applied. Therefore, when the relationship between the excitation force applied to the fruit and the acceleration of the vibration of the fruit is observed while changing the frequency, the same result as that obtained when the laser vibrometer is used can be obtained.
[0029]
In FIG. 8, the output of the acceleration sensor 23b of the impedance head 23 is fed back to one terminal of the operational amplifier 22a of the vibration controller 22 in order to keep the acceleration a constant.
Further, the output of the FFT 4 is given to the other terminal of the operational amplifier 22a in order to set a reference value for determining the excitation force.
[0030]
The acceleration of the vibration of the fruit 10 being excited is detected by the acceleration sensor 23 b, and the detection signal is input to one terminal of the frequency analyzer (FFT) 4. An output proportional to the excitation force of the impedance head 23 is input to the other terminal of the FFT 4.
The output of the FFT 4 is input to the maturity determination unit 25 in the same manner as in the first embodiment, so that a transfer function of vibration related to the fruit is obtained from the excitation force and acceleration of the fruit, and based on this transfer function The secondary resonance frequency is detected.
[0031]
The maturity determination unit 25 detects the secondary resonance frequency described above, and based on the acceleration a output from the acceleration sensor 23b of the impedance head 23 and the excitation force F output from the excitation force sensor 23a. The fruit weight m is calculated. Then, based on the secondary resonance frequency and the weight m, a relationship table prepared in advance is referred to, and the maturity of the fruit is determined and displayed.
[0032]
(Deformation)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the equivalent scope of the present invention.
For example, in the first embodiment, the method of exciting the fruit may use a speaker or a piezoelectric element other than the vibrator, and the excitation force is not a current but a voltage proportional to the excitation force is extracted and processed. It may be a signal.
[0033]
In addition, although a laser vibrometer is used as a method for obtaining the secondary resonance frequency, other methods may be used, for example, a method in which a speed or acceleration sensor is lightly brought into contact with the fruit surface, a microphone or the like is brought close to the surface, etc. But you can. That is, the method for detecting the weight of the fruit in the first embodiment may be combined with the method for obtaining the secondary resonance frequency of any conventional technique to determine the maturity of the fruit.
[0034]
In the second embodiment, in the example of FIG. 8, the vibration sensor 21 may not have a built-in acceleration sensor. However, as a method for measuring the weight of the fruit, a vibrator having a built-in acceleration sensor is used. Thus, the detection may be performed by a method according to the first embodiment.
Furthermore, the fruit maturity may be determined in combination with the secondary resonance frequency obtained by the method of the second embodiment by obtaining the weight of the fruit by any of various conventional methods.
[0035]
【The invention's effect】
As described above in detail, according to the present invention, the fruit being vibrated is controlled to vibrate at a constant acceleration, and the weight of the fruit can be detected from the vibration force and speed. The weight of the fruit can be detected during the measurement of the secondary resonance frequency of the fruit or continuously before and after that, and the judgment efficiency is greatly improved compared to the conventional technique in which the weight is separately measured by a weighing scale or the like. The required time can be shortened.
[0036]
In addition, the excitation force and the acceleration of the part to be excited are obtained between the fruit to be measured and the vibrator, the fruit is controlled to vibrate at a constant acceleration, and the acceleration is changed while changing the excitation frequency. Since the transfer function of the excitation force between the fruit and the excitation force is obtained based on the vibration force and the secondary resonance frequency of the fruit is obtained from the transfer function, it is cheaper with a much simpler configuration than before. In addition, it is possible to provide an apparatus that can be easily operated for measurement.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an explanatory diagram showing a functional system of each part of a first embodiment of a fruit ripeness measuring apparatus according to the present invention.
FIG. 2 is an explanatory diagram showing an example of a frequency analysis result for obtaining a secondary resonance frequency.
FIG. 3 is an explanatory diagram showing an example of a frequency analysis result for obtaining a secondary resonance frequency.
FIG. 4 is an explanatory diagram showing an example of a frequency analysis result for obtaining a secondary resonance frequency.
FIG. 5 is an explanatory diagram showing an example of a frequency analysis result for obtaining a secondary resonance frequency.
FIG. 6 is an explanatory diagram showing an example of a frequency analysis result for obtaining a secondary resonance frequency.
FIG. 7 is an explanatory diagram showing an example of a frequency analysis result for obtaining a secondary resonance frequency.
FIG. 8 is an explanatory diagram showing a functional system of each part of the second embodiment of the fruit tree maturity measuring apparatus according to the present invention.
FIG. 9 is an explanatory diagram showing an example of a conventional fruit tree maturity measurement system.
FIG. 10 is an explanatory diagram showing a characteristic curve representing a transfer gain of an excitation force in a fruit.
FIG. 11 is an explanatory diagram of a maturity determination curve showing determination numerical values versus measured hardness.
[Explanation of symbols]
1, 21 Exciter 1b Acceleration sensor 2, 22 Excitation controller 3 Laser vibrometer 4 FFT
5, 25 Ripeness determination unit 10 Fruit 23 Impedance head 23a Excitation sensor 23b Acceleration sensor

Claims (4)

In the method for measuring the maturity of a fruit, the second resonance frequency of the fruit and the weight of the fruit are obtained, and the maturity of the fruit is measured based on the second resonance frequency and the weight.
Find information about the excitation force and acceleration,
Referring to the information on the acceleration, vibrates so that the fruit being vibrated with a constant acceleration,
A fruit maturity measurement method, comprising: calculating a weight of the fruit based on information on the excitation force when the acceleration is kept constant. In a fruit maturity measuring apparatus for measuring the maturity of the fruit based on the secondary resonance frequency of the fruit and the weight of the fruit,
A vibration means for vibrating the fruit;
Excitation force detection means for detecting excitation force information of the excitation means;
Acceleration detecting means for detecting acceleration information of the vibrating means;
Based on the acceleration information, excitation force control means for controlling the excitation force of the excitation means so that the fruit vibrates at a constant acceleration;
Based on the excitation force information in which the acceleration is kept constant, weight calculating means for determining the weight of the fruit;
A fruit maturity measuring apparatus comprising: In the method for measuring the maturity of a fruit, the second resonance frequency of the fruit and the weight of the fruit are obtained, and the maturity of the fruit is measured based on the second resonance frequency and the weight.
Detecting information on the excitation force to the fruit and information on the acceleration of the site of vibration of the fruit,
Referring to the information on the acceleration, vibrates so that the fruit being vibrated with a constant acceleration,
While changing the excitation frequency, a transfer function of the excitation force is obtained based on information on the acceleration and the excitation force, and a secondary resonance frequency of the fruit is obtained from the transfer function. Method for measuring the ripeness of fruit. In the fruit maturity measuring apparatus for determining the maturity of the fruit based on the secondary resonance frequency of the fruit and the weight of the fruit,
Vibration means for applying vibration to the fruit;
Excitation force detection means for detecting excitation force information of the excitation means;
An acceleration detecting means that is inserted between the vibrating means and the fruit, and detects acceleration information of a portion to be vibrated;
Frequency analysis means for performing frequency analysis based on the excitation force information and the acceleration information of the portion to be excited,
Based on the acceleration information, an excitation force control means capable of controlling the excitation means so that the fruit vibrates at a constant acceleration and continuously changing the excitation force;
Based on the analysis result of the frequency analysis means, a transfer function characteristic of the excitation force between the vibration means and the fruit is obtained, and a resonance frequency calculation means for obtaining a secondary resonance frequency of the fruit from the transfer function characteristic; ,
An apparatus for measuring the maturity of a fruit, comprising:

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