JP2000097920A - Apparatus for measuring maturity of fruit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make detectable a secondary resonant frequency at a high speed and correctly by performing a frequency analysis based on a shake force information of a shaking means shaking a fruit and an information of the shaken fruit. SOLUTION: An FFT analyzer 11 generates random wave signals and carries out an FFT(fast Fourier transform) process and the other operation processes. An HPF(high pass filter) 12 passes only random wave signals of a predetermined frequency among the signals output from the FFT analyzer 11. A shake controller 13 controls a shaking device 14 on the basis of the random wave signals passing the HPF 12. The shaking device 14 shakes on the basis of a control signal a fruit 1 to be measured. An acceleration sensor 15 picks up a shake signal of the shaking device 14 and inputs an output to the FFT analyzer 11. A laser vibration meter 16 detects a signal of a shaken surface of the fruit 1 and inputs an output to the FFT analyzer 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention measures the degree of maturity of fruits (hereinafter, referred to as ripeness) before shipment of fruits and vegetables that eat the real part (hereinafter, referred to as fruits). The present invention relates to an apparatus for measuring the ripeness of fruits.

[0002]

2. Description of the Related Art Conventionally, this kind of fruit ripeness measuring device is
The value obtained from the secondary resonance frequency and weight of the fruit is
It utilizes the property of having a high correlation with fruit ripeness. For example, a fruit is placed on a shaker of a shaker, shaken by a sine wave, and the shake frequency is continuously changed ( The secondary resonance frequency is detected by measuring a change in the speed or acceleration of the vibration that appears on the surface of the fruit when the sweep is performed.

[0003]

However, in the above-mentioned prior art, the secondary resonance frequency is detected by performing a sine sweep and measuring the change in the speed or acceleration of the vibration appearing on the surface of the fruit. Therefore, there is a problem that it takes time to detect the secondary resonance frequency. It is also conceivable to use random waves in order to perform high-speed processing. However, another problem occurs in that the fruit jumps in the low frequency region and moves on the mounting jig.

[0004] It is an object of the present invention to provide a maturity measuring apparatus capable of detecting a secondary resonance frequency at high speed and accurately.

[0005]

In order to solve the above-mentioned problems, the invention of claim 1 provides a method for judging the ripeness of a fruit based on a secondary resonance frequency of the fruit and the weight of the fruit. In the ripeness measuring device, a vibrating means for vibrating the fruit, a vibrating information detecting means for detecting vibrating force information of the vibrating means, and an excitation of the fruit vibrated by the vibrating means. Excited information detecting means for detecting excitatory information, frequency analysis is performed based on the excitatory force information and the excited information to determine a transfer function characteristic of the fruit, and a phase of the transfer function characteristic is predetermined. And a resonance frequency calculating means for calculating a secondary resonance frequency of the fruit from the frequency at which the value has reached the value.

According to a second aspect of the present invention, in the fruit ripeness measuring apparatus according to the first aspect, the resonance frequency calculating means includes:
Among the frequencies of the plurality of sampling points where the phase of the transfer function characteristic is near the predetermined value, the frequency having the largest gain is determined as the temporary secondary resonance frequency, and the plurality of frequencies before and after the temporary secondary resonance frequency are determined. A true secondary resonance frequency is calculated based on the value of the gain at the sampling point.

According to a third aspect of the present invention, in the fruit ripeness measuring apparatus according to the first aspect, the vibrating means applies vibration to the fruit by a random wave cut in a low frequency region. It is a device for measuring the ripeness of fruit.

According to a fourth aspect of the present invention, in the fruit ripeness measuring apparatus according to the third aspect, the resonance frequency calculating means includes:
In the low-frequency region, the phase unwrapping process is stopped, and the apparatus is a fruit ripeness measuring device.

[0009]

Embodiments of the present invention will be described below in more detail with reference to the drawings. FIG.
1 is a block diagram showing an embodiment of a fruit ripeness measuring device according to the present invention. The fruit ripeness measuring apparatus 10 of this embodiment includes an FFT analyzer 11, an HPF (high-pass filter) 12, a vibration controller 13, and a vibrator 1.
4, an acceleration sensor 15, a laser vibrometer 16 and the like.

An FFT analyzer 11 generates a random wave signal and performs FFT (fast Fourier transform) processing.
An analyzer capable of performing other arithmetic processing.

The HPF 12 is a filter that allows only a predetermined frequency of the random wave signal output from the output terminal (OUT) of the FFT analyzer 11 to pass. In this embodiment, in order to detect the maturity at high speed, by performing an average process of about 10 using a random wave,
Higher speed was made possible. However, in the low frequency region (~ 100
(Hz), the vibration displacement is large, and the fruit 1 jumps or moves on the mounting jig 14a. Therefore, the HPF 12 having a cutoff frequency of about 100 Hz is inserted into the random wave so as to eliminate the influence of the low frequency. Further, since the secondary resonance frequency of the fruit is higher than 100 Hz, even if the frequency in this region is removed, there is no problem in measuring the ripeness.

The excitation controller 13 controls the excitation unit 14 based on the random wave signal passed through the HPF 12. The shaker 14 is configured to measure the fruit 1 to be measured based on a control signal from the shake controller 13.
And a mounting jig 14a on which the fruit 1 is placed.

The acceleration sensor 15 is a sensor that picks up a vibration signal (acceleration in this case) of the vibrator 14, and its output is connected to one input terminal (IN 1) of the FFT analyzer 11.

The laser vibrometer 16 is a sensor for detecting an applied signal on the surface of the fruit 1, and its output is F
It is connected to the other input terminal (IN2) of the FT analyzer 11. The laser vibrometer 16 is used for the sensor head 1
By using the Doppler effect, a signal proportional to the speed of the surface of the fruit 1 can be extracted by 6a.

FIG. 2 is a flowchart for explaining the operation of the embodiment of the fruit ripeness measuring apparatus according to the present invention. F
The FT analyzer 11 outputs a random wave signal from the output terminal OUT (S101). The random wave signal is HP
After passing through F12 and the frequency below 100 Hz is cut off, the vibrator 14 is vibrated via the vibration controller 13. For this reason, the vibrator 14 is
Since the frequency below z is cut off, the fruit 1 does not jump or move on the mounting jig 14a.

After the fruit 1 is vibrated by the vibrator 14, the FFT analyzer 11 receives a vibration signal (acceleration signal) from the acceleration sensor 15 (S 102), and receives a vibration signal (velocity) from the laser vibrometer 16. Signal (S10).
3). Then, the FFT analyzer 11 obtains a transfer function of the fruit 1 (see FIG. 3) based on the acceleration signal and the speed signal (S104).

Next, the FFT analyzer 11 performs a phase detection process (S107). Before that, the FFT analyzer 11 needs to perform a phase unwrap process (S106) in order to detect the phase -270 ° which is the secondary resonance frequency. There is.

The phase unwrapping process includes the following (1) to
The processing of (3) is performed. (1) Calculate the phase within the range of ± 180 °. (2) Calculate the previous value, IF | current value-previous value |> 180 ° then IF Img <0 then RAP COUNTER + 1 IF Img> 0 then RAP COUNTER-1 END IF (3) Phase to be obtained = Current value + RAP COUNTER x
360 °

Here, the low frequency of 100 Hz or less corresponds to HP
The phase is cut in F12. In this region, the phase to be obtained is the phase of a noise component that is not a vibration component, and the obtained value is random. Therefore, since this low frequency region has no physical meaning, if the phase unwrapping process is performed in this low frequency region, the initial phase becomes 0 °.
Instead, it may be −360 ° or + 360 ° (see FIGS. 4, 5, and 6).

Therefore, this frequency range is f> 100 Hz
Whether or not it is detected (S105), and if it is less than that (S105: NO), the phase unwrapping process (increment and decrement of the wrap counter) is not performed.

Next, the FFT analyzer 11 performs a process of detecting the secondary resonance frequency (S108). In this embodiment, as a method of detecting the secondary resonance frequency, the frequency at which the phase reaches −270 ° is set as the second resonance frequency, focusing on the phase of the transfer function.

FIG. 7 is a diagram for explaining the detection processing of the secondary resonance frequency of the fruit ripeness measuring apparatus according to the present embodiment. Here, 5 before and after the frequency at which the phase reached −270 °
Among the frequencies at the points (P1 to P5), the frequency having the largest gain is defined as a temporary secondary resonance frequency (P3).
From the provisional secondary resonance frequency (P3) and the gain values of two points before and after (P1, P2 and P4, P5),
Object line approximation is performed by the least square method, and the peak frequency of the object line is defined as a true secondary resonance frequency (P0). This calculation can increase the frequency resolution.

On the other hand, the mass of the fruit 1
Before loading on 4, the weight is measured by another measuring device such as a weighing scale, and the result is displayed on the display of the weighing scale. Then, the judgment of the maturity is made by inputting the secondary resonance frequency and the numerical value displayed on the display of the weighing scale to a personal computer or the like, and by using the previously input program, the secondary resonance frequency and the weight of the fruit are determined. The relational expression between the obtained numerical value and the ripeness of the fruit is calculated, and the calculation is performed with reference to data (table) corresponding to the kind of the fruit to be determined. The result is displayed on the display unit of the personal computer.

As described above, according to the present embodiment, the following effects can be obtained. (1) Since the frequency at which the phase of the transfer function reaches −270 ° is detected as the second resonance frequency, the second resonance frequency can be obtained at high speed. (2) Of the five frequencies before and after the frequency at which the phase has reached -270 °, the frequency with the largest gain is set to the temporary second
Object line approximation is performed by the least squares method from the provisional secondary resonance frequency and the gain value at each of two points before and after the provisional secondary resonance frequency. , The resolution of the frequency can be increased.

(3) Since the frequency of 100 Hz or less is cut off, the fruit 1 does not jump or move on the mounting jig 14a. (4) When the frequency domain is equal to or lower than 100 Hz, the phase unwrapping process is not performed, so that the initial phase can always start from 0 °.

(Modifications) Various modifications and changes are possible without being limited to the embodiment described above, and these are also within the equivalent scope of the present invention. For example, the detection of the excitation signal is described using an acceleration sensor as an example, but another force sensor may be used.

[0027]

As described above, according to the present invention,
The secondary resonance frequency of the fruit can be detected at high speed and with high accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a fruit ripeness measuring apparatus according to the present invention.

FIG. 2 is a flowchart illustrating an operation of the embodiment of the fruit ripeness measuring device according to the present invention.

FIG. 3 is a diagram showing a transfer function obtained from the fruit ripeness measuring apparatus according to the present embodiment.

FIG. 4 is a diagram illustrating a transfer function in which the phase is random and the initial phase is + 360 ° in a low-frequency region of the fruit ripeness measuring apparatus according to the present embodiment.

FIG. 5 is a diagram showing a transfer function of the fruit ripeness measuring apparatus according to the present embodiment in which the phase is random in the low frequency region and the initial phase is −360 °.

FIG. 6 is a diagram showing a coherence function obtained from the fruit ripeness measuring apparatus according to the present embodiment.

FIG. 7 is a diagram illustrating a process of detecting a secondary resonance frequency of the fruit ripeness measuring apparatus according to the present embodiment.

[Explanation of symbols]

 Reference Signs List 10 Fruit ripeness measuring device 11 FFT analyzer 12 HPF (high pass filter) 13 Vibration controller 14 Vibrator 15 Acceleration sensor 16 Laser vibrometer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shoji Terasaki 1-8, Koshinmachi, Takamatsu City, Kagawa Prefecture F-term in Matsushita Hisashi Denshi Kogyo Co., Ltd. 2G047 AA12 BA04 BC00 BC04 EA09 EA10 GF11 GG01 GG24 GG16 GG24

Claims (4)

[Claims] 1. A fruit ripeness measuring device for judging a ripeness of the fruit based on a secondary resonance frequency of the fruit and a weight of the fruit, wherein a vibration means for applying vibration to the fruit; Excitation information detection means for detecting excitation information of the vibration means, excitation information detection means for detecting the excitation information of the fruit vibrated by the vibration means, A frequency analysis is performed based on the vibrated information to obtain a transfer function characteristic of the fruit, and a resonance frequency for obtaining a secondary resonance frequency of the fruit from a frequency at which the phase of the transfer function characteristic reaches a predetermined value. And a calculating means. 2. The fruit ripeness measuring apparatus according to claim 1, wherein the resonance frequency calculating means has a gain of a phase of the transfer function characteristic which is the highest among a plurality of sampling points near the predetermined value. Is determined as a temporary secondary resonance frequency, and a true secondary resonance frequency is calculated based on gain values at a plurality of sampling points before and after the temporary secondary resonance frequency. Fruit ripeness measuring device. 3. The fruit ripeness measuring apparatus according to claim 1, wherein the vibrating means vibrates the fruit by a random wave obtained by cutting a low-frequency region. measuring device. 4. The fruit ripeness measuring device according to claim 3, wherein the resonance frequency calculating means stops the phase unwrapping process in the low frequency region.