JPH1073572A - Method and device for sorting vegetables and fruits - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for sorting vegetables and fruits by which the ripeness of relatively soft vegetables and fruits, such as the tomato, kiwi fruit, etc., can be measured. SOLUTION: The driving section 17 of an exciting machine gives vibrations to a vegetable or fruit 11 to be measured. An acceleration sensor 18 accurately measures the vibrations given to the vegetable or fruit 11 and inputs the measured vibrations to the input A of a Fourier transformation analyzer 15. A laser Doppler vibration meter 13 measures the vibrations of the excited part and opposite-side upper surface of the vegetable or fruit in a non-contacting state and inputs the vibrations to the input B of the analyzer 15. The analyzer 15 measures gain characteristics and discriminates the ripeness of the vegetable or fruit 11 by using both a resonance frequency and the damping factor B/A (dB) of the vibrations at a resonance point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention measures the ripeness of fruits and vegetables for determining the optimal harvest time and the shelf life after harvesting, and selects the fruits and vegetables for providing high added value to consumers and producers. And a fruit sorting apparatus.

[0002]

2. Description of the Related Art In general, fruits and vegetables become softer due to changes in physical properties of cell walls and intracellular substances accompanying growth and maturation. Therefore, the ripeness can be determined by measuring the changes in the viscosity and elasticity of the fruits and vegetables. Conventionally, hardness, that is, elasticity, has been mainly discussed as an index of ripeness of fruits and vegetables, and the effect of viscosity has not been discussed.

Conventionally, a method for measuring hardness using the vibration of fruits and vegetables is disclosed in Japanese Patent Application Laid-Open No.
No. 35962 is known. In these methods, the fruits and vegetables are vibrated with a vibrator or a hammer, and the resonance frequency or anti-resonance frequency is calculated by measuring the local vibration of the fruits and vegetables using a microphone or a vibrometer, and the fruits and vegetables are calculated from these values. They are trying to measure hardness and estimate ripeness.

[0004]

However, fruits and vegetables, such as apples, watermelons, and melons, which are entirely hard or whose surface is covered with a hard skin, mainly have a vibrating part which has many characteristics of an elastic body. Therefore, even if the maturity is discussed only by changing the resonance frequency, it is possible to cope with it. I was Particularly with such soft fruits and vegetables, it was difficult to even produce a hammering sound without damage.

[0005]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention seeks to measure the maturity of fruits and vegetables using not only the resonance frequency but also the attenuation rate of vibrations inside the fruits and vegetables. According to the present invention, the change in the elastic modulus of fruits and vegetables mainly appears as a change in the resonance frequency, and the change in viscosity changes mainly as a difference in the damping rate of vibration inside the fruits and vegetables. Even for soft fruits and vegetables, the characteristics of changes in physical properties inside can be measured accurately, and an index showing the characteristics of an accurate ripeness index can be created.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention comprises applying a vibration to a fruit or vegetable to be measured, and measuring both the resonance frequency of the fruit and vegetable and the attenuation rate of the applied vibration inside the fruit and vegetable. By measuring the ripeness of the fruits and vegetables, by measuring not only the resonance frequency but also the attenuation rate, the ripeness of not only hard fruits and vegetables but also soft fruits and vegetables with a large viscous effect is accurately measured. It has the effect of being able to measure.

According to a second aspect of the present invention, there is provided a vibrating means for applying a vibration to a local part of a fruit and vegetable, a first vibration detecting means for measuring the vibrated vibration, and a local part of the vegetable or vegetable vibrated by the vibration. Second vibration detecting means for measuring vibration, means for calculating a resonance frequency and a damping rate of vibration inside the fruit and vegetable based on detection outputs of both vibration detecting means, and a fruit and vegetable based on the resonance frequency and the damping rate. And a means for measuring ripeness, which can realize a fruit and vegetable sorting device that can accurately measure ripeness from hard fruits and vegetables close to an elastic body to soft fruits and vegetables having a large influence of viscosity. It has the action of:

[0008] The invention described in claims 3 and 4 is:
The attenuation rate is characterized by using a value at the resonance point of the fruits and vegetables, and using the value at this point has an effect that the characteristic of the viscosity of the fruits and vegetables can be particularly remarkably expressed.

(Embodiment) The first aspect of the present invention will be described below.
An embodiment of the invention described in claim 4 will be described with reference to FIGS. 1, 2, and 3. FIG.

FIG. 1 shows an example of a device configuration diagram for implementing the present invention. In FIG. 1, reference numeral 11 denotes a fruit or vegetable to be measured, 12 denotes a laser beam, and 13 denotes a laser Doppler vibrometer. A sensor head, 14 is a signal converter of a laser Doppler vibrometer, 15 is a Fourier transform analyzer, 16 is a control unit of a shaker, 17 is a drive unit of a shaker, 18 is an acceleration sensor, and 19 is a sample table. .

This device configuration is an example in which vibrations of fruits and vegetables given by a vibrator are measured in a non-contact manner by a laser Doppler vibrometer. And a signal processing unit, so that different device configurations corresponding to each unit can be used.

The operation of the fruit and vegetable ripeness sorting device configured as described above will be described below. First, the fruits and vegetables 11 are placed on a sample table 19 on a shaker. The sine wave vibration of 10 Hz to 2 kHz is sequentially applied to the fruits and vegetables 11 while the driving unit 17 controls the vibration unit to make the acceleration of the vibration substantially constant with respect to the frequency by the control unit 16 of the shaker. The acceleration of the vibration applied to the fruits and vegetables 11 is accurately measured by the acceleration sensor 18 and input to the input A of the Fourier transform analyzer 15. In this case, in addition to the acceleration of the vibration, a force, a speed converted from the force, and a displacement signal may be input. On the other hand, the sensor head 13
Irradiates a laser beam 12 from the substrate, and measures the speed of vibration at that point in a non-contact manner using a laser Doppler vibrometer. This is input to the input B of the Fourier transform analyzer 15. Also in this case, in addition to the vibration speed, an acceleration, displacement, or force signal obtained by converting the vibration speed may be input.

Finally, the input A of the Fourier transform analyzer 15
And B are subjected to signal processing, and in the vibration modal analysis, an attenuation rate B / A (d) between the input and output of the fruit vibration with respect to a frequency generally called a gain characteristic.
Measure B). In the above example, a sine wave was used as the input vibration when exciting the fruit, but a pulse wave, burst wave,
A random wave may be used. When these are used, high-speed measurement using Fourier transform is possible.

FIG. 2 shows an example of gain characteristics measured using the above-described equipment configuration using tomato (cultivar, Momotaro) as fruits and vegetables. In the measurement of the attenuation rate in this case, an acceleration signal from the acceleration sensor 18 is used as the input A, and an acceleration signal obtained by differentiating the velocity signal measured once with the laser Doppler vibrometer once is used as the input B. Generally 8 for tomatoes
Resonance frequencies appear near 0, 500, and 700 Hz. 8
The resonance point around 0 Hz is strongly dependent on the way the tomato is placed on the sample table 19, and no clear peak appears around 700 Hz.

Attention is paid to the resonance point near 500 Hz, and plots the relationship between the resonance frequency and the attenuation rate at the resonance point when three types of tomatoes having different ripeness are ripened at 15 ° C. for 18 days during fruit picking. FIG. 3 shows the result. Ripeness means that the whole is already ripe at the time of thinning, coloration starts with pinking only at the top of the fruit at the time of fruiting and other parts are green, and immature means green tomatoes at the time of fruiting. I have. In this case, the value at the resonance point is used as the damping factor. This is based on the fact that the attenuation effect appears most prominently near the peak, and it is necessary to use the value at the resonance point as the damping factor. There is no.

In FIG. 3, the above three types of tomatoes are all 2
On the fourth, ninth and ninth days, the resonance frequency decreases with ripening, and the attenuation rate tends to increase. In addition, by selecting both the resonance frequency and the attenuation rate from the viewpoints, the three types of tomatoes can be clearly classified even if the ripening progresses after thinning.
In the case of immature, the resonance frequency is high and the attenuation rate is small as compared with the others. In the case of the immature state, the resonance frequency is hardly changed but the attenuation rate is large as compared with the beginning of coloring. From the viewpoint of the conventional resonance frequency alone, it is difficult to judge the difference between the beginning of coloring and the ripeness, although it is possible to judge the immaturity and other judgments. It becomes possible. That is, it is possible to determine a ripe fresh and nutritious tomato at the time of fruiting, which is expected to be the most valuable in the market.

In general, most tomatoes that are distributed in the market are plucked at the beginning of coloring, undergo a distribution process, and are adjusted so that the whole is almost pink at the time of retailing. However, there is still little variation in maturity at the retail stage. As shown in FIG. 3, it is possible to manage the maturity in the distribution process by utilizing the obvious changes in the resonance frequency and the attenuation rate accompanying the ripening of the tomato.

In recent years, varieties of various fruits and vegetables, such as varieties that have a long life after ripeness, have been actively used by genetic manipulation. If the varieties are different, the internal elastic modulus and viscosity and the manner of these changes due to ripening are different, so if the pattern of each breed is recognized in advance in terms of the resonance frequency and the damping rate, Ripeness management is also possible.

[0019]

As described above, according to the present invention, the characteristics of the elasticity and viscosity inside the fruits and vegetables are obtained by applying vibrations to the fruits and vegetables and measuring both the resonance frequency of the fruits and vegetables and the attenuation rate of the vibrations inside the fruits and vegetables. And can realize an excellent vegetable and vegetable ripeness selection device which can be operated at high speed and online.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a fruit sorting apparatus to which a fruit / vegetable fruit sorting method according to an embodiment of the present invention is applied.

FIG. 2 is a diagram showing gain characteristics of tomato vibration in the embodiment of the present invention.

FIG. 3 is a diagram showing the relationship between the resonance frequency and the attenuation rate of tomatoes having different ripeness levels during fruit cutting according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Fruit and vegetable 12 Laser beam 13 Sensor head of laser Doppler method 14 Signal converter of laser Doppler method 15 Fourier transform analyzer 16 Control part of shaker 17 Drive part of shaker 18 Acceleration sensor 19 Sample stand

Claims (4)

[Claims] The present invention is characterized in that the ripeness of the fruits and vegetables is measured by applying vibration to the fruits and vegetables to be measured and measuring both the resonance frequency of the fruits and vegetables and the attenuation rate of the applied vibration inside the fruits and vegetables. Fruit and fruit selection method. 2. The fruit and fruit selection method according to claim 1, wherein a value at a resonance point of the fruit or vegetable is used as the attenuation rate. 3. Exciting means for applying vibration to a local portion of a fruit or vegetable,
The first vibration detection means for measuring the vibration that was excited, the second vibration detection means for measuring the local vibration of the fruits and vegetables vibrated by the excitation, and based on the detection output of both vibration detection means, A fruit and vegetable sorting apparatus comprising: means for calculating a resonance frequency and a damping rate of vibration inside a fruit and vegetable; and means for measuring the ripeness of the fruit and vegetable from the resonance frequency and the damping rate. 4. The fruit and vegetable sorting apparatus according to claim 3, wherein a value at a resonance point of the fruit or vegetable is used as the attenuation rate.