JP2006300724A - Device for determining degree of ripeness - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact portable device for determining a degree of ripeness capable of reducing noise vibration, and capable of obtaining precisely vibration of a specimen. <P>SOLUTION: Vibration is applied to the specimen 20 by an oscillator 6, the vibration of the specimen 20 is detected based on a strain due to the vibration of the specimen 20, by a vibration sensor 7 provided with a detecting element for converting the strain into an electric signal, the first arm 9 arranged with the oscillator 6 and the second arm 10 arranged with the vibration sensor 7 are moved to sandwich the specimen 20 between the arms, and moving amounts of the arms are acquired to calculate a diameter of the specimen 20 by a diameter measuring part 8. The vibration detected by the vibration sensor 7 is analyzed to detect a secondary resonance frequency, and an elastic modulus is calculated based on the secondary resonance frequency and the diameter measured by the diameter measuring part 8 to determine the degree of ripeness. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a maturity determination device that determines maturity of agricultural products and the like.

  Conventionally, the harvest time and ripeness of fruits and the like have been determined by human sense based on observation of changes in color and size, taste and other experiences. However, many years of experience are required before an accurate judgment can be made, so there is a problem that it takes a lot of time for human resource development and costs such as personnel expenses. In addition, there is a risk that mistakes may occur in judgment based on human senses.

  Therefore, a highly objective apparatus for determining the harvest time and ripeness of fruits and the like has been proposed. For example, the present applicants analyze the frequency of the vibration of the subject detected when the subject is vibrated, and detect the resonance frequency that is proportional to the elastic modulus of the subject to determine the maturity of the fruit. A technique for determining is proposed (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 9-236587 Japanese Patent Laid-Open No. 9-274022

  In the technique described in Patent Document 1, since vibration is measured by the laser Doppler method, the apparatus becomes large.

  Further, although it has been proposed to use a microphone for vibration detection (see, for example, Patent Document 2), since the obtained vibration includes noise vibration of external sound, the resonance frequency can be detected. It was difficult.

  The present invention has been proposed in view of such conventional circumstances, and provides a portable maturity determination device that can reduce noise vibration and accurately obtain vibration of a subject. For the purpose.

  In order to solve the above problem, a maturity determination apparatus according to the present invention includes an oscillation source that applies vibration to a subject and a detection element that converts strain into an electrical signal, and the detection element is distorted by the vibration of the subject. A vibration sensor for detecting the vibration of the subject, an acquisition unit for obtaining the diameter of the subject, and analyzing the vibration detected by the vibration sensor to detect a secondary resonance frequency, and detecting the secondary resonance frequency. And an analysis determination unit that calculates an elastic modulus of the subject based on the resonance frequency and the diameter, and determines the maturity of the subject based on the elastic modulus.

  The vibration sensor has a detection element that converts strain into an electrical signal, and the detection element detects the vibration of the subject by distortion due to the vibration of the subject. It can be obtained well and stably.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. The maturity determination apparatus shown as a specific example analyzes the vibration obtained by exciting the subject, calculates the elastic modulus by detecting the secondary resonance frequency that is proportional to the elastic modulus of the subject, The maturity of the subject is determined based on the elastic modulus.

  FIG. 1 is a block diagram schematically illustrating the overall configuration of the maturity determination apparatus 1. The maturity determination apparatus 1 includes a measurement unit 2 that measures the diameter and vibration of a subject, an analysis determination unit 3 that calculates an elastic modulus based on the measured diameter and vibration, and determines the maturity, and a determination result Display unit 4 and a control unit 5 for comprehensively controlling each component unit.

  As shown in FIG. 2, the measurement unit 2 includes an oscillation source 6 that applies vibration to the subject 20, a vibration sensor 7 that detects the vibration of the subject 20, and a diameter measurement unit 8 that measures the diameter of the subject 20. Have. The oscillation source 6 is provided on the first arm 9. The first arm 9 is further provided with a contact sensor 61 for detecting contact with the subject. The vibration sensor 7 is provided on the second arm 10. Then, the first arm 9 or the second arm 10 moves the slider 11.

  The oscillation source 6 applies vibration to the subject 20 by hitting. The method for applying vibration needs to be selected according to the type of the subject 20. For example, if the subject 20 is heavy, such as a watermelon or melon, it is necessary to apply a large vibration to generate resonance, and therefore it is preferable to apply a vibration by striking.

  FIG. 3 is a schematic diagram showing the oscillation source 6 when vibration is applied by impact. The oscillation source 6 applies vibration to the subject 20 when the oscillation head 21 strikes the subject 20. The tip of the oscillation head 21 is covered with a shock absorber 22 so as not to damage the subject. Further, in order to prevent the oscillation head 21 from tapping twice and to suppress vibration propagation to the oscillation head arm 23, the oscillation head 21 and the oscillation head arm 23 are fixed via an impact absorbing material 24 such as a polymer gel sheet. Yes. As a result, noise vibration to the entire mechanism due to oscillation can be reduced, and a so-called piercing method can be realized in which the oscillation head 21 is kept in contact with the subject 20 even after the subject 20 is hit. Can do.

  The oscillation source 6 is provided with a contact plate 25 for fixing the subject 20 with the subject 20 interposed therebetween. The contact plate 25 is in point contact with the subject 20 by the protrusion 30 as shown in FIG. When the contact area between the contact plate 25 and the subject 20 increases, the absorption rate of vibration increases. Therefore, the contact with the subject 20 is preferably a two-point contact that can sandwich the subject 20. Further, the oscillation head 21 preferably passes through the center between the two points in contact with each other and strikes the subject 20.

  The oscillation switch 26 is integrated with a hub slider 27, and the oscillation head starting hub 28 is rotated by the hub slider 27. When the oscillation head starting hub 28 rotates, the oscillation head arm 23 is driven and the oscillation force generating spring 29 is bent.

  When applying vibration to the subject 20, the oscillation switch 26 is slid downward. Then, the hub slider 27 integrated with the oscillation switch 26 is lowered and the oscillation head starting hub 28 is rotated. As a result, the oscillation head arm 23 is tilted away from the subject 20 and the oscillation force generation spring 29 is bent, so that the excitation force is stored. When the oscillation switch 26 is further lowered, the oscillation head 21 strikes the subject 20 by the repulsive force of the oscillation force generation spring 29.

  Note that the oscillation source 6 shown in FIG. 3 is an example of a mechanism for starting a manual vibration operation, but may be automatically excited using a drive mechanism such as a motor and a cam.

  The excitation force generated by the hitting requires strength that causes resonance vibration in the subject 20. When the excitation force is small, the vibration only propagates and attenuates inside the subject 20, and sufficient resonance vibration cannot be generated in the subject 20. This excitation energy P is expressed by equation (1) where m is the weight and v is the velocity.

  In order to increase the excitation energy, it is necessary to increase the weight of the oscillation head 21 or increase the excitation speed. However, on the contrary, the reaction force against the impact applied to the subject 20 increases, and the vibration to the first arm 9 on the oscillation side may not be absorbed even if the shock absorber is enlarged. Therefore, in order to efficiently apply the striking force to the subject 20, the impulse (force × time) is increased. Specifically, even after the oscillating head 21 comes into contact with the subject 20 by hitting, the hitting force is continuously applied by performing so-called piercing that keeps touching the subject. Thereby, even if the oscillation head 21 is not made heavy, the striking force can penetrate into the subject 20 and self-excited vibration can be generated in the subject 20.

  The vibration sensor 7 has a housing structure in which the oscillation source 6 and the vibration sensor 7 are integrated, so that accurate vibration analysis of the subject 20 becomes difficult. This is because vibrations such as sneak current from the oscillation source side and vibrations received by the vibration sensor 7 from the subject 20 are propagated to the vibration sensor 7 and the second arm 10, so This is because the resonance vibration of the second arm 10 itself is superimposed on the vibration of the subject 20. Therefore, the vibration sensor 7 needs to have a structure that can accurately detect the vibration of the subject 20 without being affected by noise such as external sound.

  Therefore, the vibration sensor 7 includes a detection element 51 that converts strain such as a plate-type piezoelectric element into an electric signal as shown in FIG. Thereby, the influence of external sound can be eliminated.

  Further, a point contact projection 52 is provided on the plate-type detection element 51 to reduce the contact area with the subject 20 as much as possible to improve the resolution of vibration of the subject 20. When the contact area with the subject is large, the displacement of the detection element surface is superimposed and a nonlinear element is added, which makes vibration analysis difficult.

  Further, a detection element receiver 53 made of a highly rigid metal or the like is provided on the back surface of the detection element 51. Thereby, the distortion of the detection element 51 is prevented as much as possible. When the surface distortion of the detection element 51 increases, vibration signals having different frequencies with respect to the original vibration are extracted.

  Furthermore, a thin vibration amplification sheet 54 is sandwiched between the detection element 51 and the detection element receiver 53. Thus, the plate-type detection element 51 is prevented from being greatly distorted, and the vibration of the subject 20 is displaced. This is because when the detection element 51 is directly attached to the detection element receiver 53, almost no displacement occurs.

  Further, an impact absorbing material 55 such as a polymer gel sheet is installed between the detecting element receiver 53 and the holder 56, and the detecting element receiver 53 is held by the impact absorbing material 55 so that the detecting element receiver 53 does not directly contact the holder 56. To do. Thereby, it is possible to prevent the vibration from the casing of the vibration sensor 7 and the vibration from the detection element 51 from propagating to the second arm 10.

  With the vibration sensor 7 having such a structure, the influence of vibration noise can be reduced to the minimum and vibration can be detected with high accuracy. Further, by providing such a vibration sensor 7, it is possible to provide a small and portable maturity determination device 1.

  The diameter measuring unit 8 measures the diameter of the subject by sliding the first arm 9 or the second arm 10 and sandwiching the subject 20. Specifically, the diameter of the subject 20 is calculated by measuring the distance between the oscillation source 6 and the vibration sensor 7.

  For example, in the measurement unit 2 shown in FIG. 2, the first arm 9 in which the oscillation source 6 is arranged and the second arm 10 in which the vibration sensor 7 is arranged simultaneously hold the subject 20 between the arms. Translate. At this time, the diameter measuring unit 8 can calculate the diameter of the subject 20 by acquiring the movement amount of the arm.

  FIG. 6 is a block diagram illustrating a configuration of the analysis determination unit 3 illustrated in FIG. The analysis determination unit 3 includes an amplification unit 71 that amplifies the vibration waveform acquired from the measurement unit 2 described above, a filter 72 that removes noise of the vibration waveform, and an A / D conversion that converts an analog signal of the vibration waveform into a digital signal. Unit 73, a waveform extraction unit 74 that extracts a predetermined region of the vibration waveform, an FFT (Fast Fourier Transform) calculation unit 75 that performs fast Fourier transform on the extracted vibration waveform, and a secondary resonance frequency from the fast Fourier transformed signal The elastic modulus is calculated from the secondary resonance frequency, the detection unit 76 that detects the diameter, the diameter calculation unit 77 that calculates the diameter of the subject, the correction unit 78 that corrects the secondary resonance frequency based on the diameter of the subject. And a determination unit 79 for determining maturity.

  The input vibration waveform is amplified by the amplifying unit 71 so as to match the input gain of the A / D converting unit 73, noise of high frequency components is removed by the filter 72, and the A / D converting unit 73 removes the analog signal from the analog signal. Converted to a digital signal. This vibration waveform includes not only the vibration of the subject but also the vibration of the excitation mechanism, the vibration receiving mechanism, the housing, etc. of the measurement unit 2. Therefore, the signal extraction unit 74 extracts a predetermined time region from such a vibration waveform. Specifically, for example, tC1 and tC2 are removed from the vibration waveform shown in FIG. 7A as shown in FIG. 7B, and a time domain tv effective for detecting the secondary resonance frequency is extracted.

  The time domain tv to be extracted is set for each type of subject because the duration of the vibration waveform and the attenuation ratio per unit time differ depending on the subject. For example, the vibration waveform of an apple has a short duration and a large attenuation rate per unit time. On the other hand, the vibration waveform of watermelon has a long duration and a small attenuation rate per unit time. By setting the time domain tv based on such characteristics, noise vibrations of the vibration mechanism, vibration receiving mechanism, housing, etc. of the measurement unit 2 included in the vibration waveform can be reduced.

  The vibration waveform extracted by the signal extraction unit 74 is subjected to fast Fourier transform by the FFT calculation unit 75, and the frequency component is analyzed. FIG. 8A is a diagram showing a waveform obtained by fast Fourier transform of a vibration waveform subjected to extraction processing, and FIG. 8B is a diagram showing a waveform obtained by performing fast Fourier transform on a vibration waveform not subjected to extraction processing. As can be seen by comparing FIG. 8A and FIG. 8B, the peak of the secondary resonance frequency waveform indicated by the broken line is emphasized by the extraction process, so that the detection unit 76 makes the secondary resonance frequency highly sensitive. Can be detected.

  The resonance frequency of each order obtained by the extraction process has a unique value depending on the subject. The primary resonance frequency is a frequency that causes a part of the subject to vibrate with respect to the applied vibration. The secondary resonance frequency is a self-excited vibration frequency in which the entire subject resonates due to vibration and the subject expands and contracts. The height of the frequency is proportional to the elastic modulus. That is, the secondary resonance frequency shifts to the lower frequency side as the fruit as the subject ripens and the elastic modulus decreases.

  The diameter calculation unit 77 approximates the mass m of the subject using the equation (2) using, for example, the average density coefficient ρ per unit volume and the diameter d measured by the diameter measurement unit 8.

The elastic modulus of the subject, using the mass m and the secondary resonance frequency f ₂ which is known to be calculated by the following equation.

  In the present embodiment, the elastic modulus can be expressed by the following equation because the elastic modulus transition of the subject, that is, the relative value of the elastic modulus may be obtained.

Further, the correction unit 78 corrects the elastic modulus using the mass approximated from the diameter by the diameter calculation unit 77. This secondary resonant frequency f ₂ ² is inversely proportional to the mass m of the object.

  The determination unit 79 determines the maturity of the subject based on the elastic modulus data thus calculated. This determination is performed based on the elastic modulus accumulated for each type of subject, and the harvest time can be determined based on the change over time in the elastic modulus. For example, in the case of a fruit whose elastic modulus decreases by 0.1 per day, the difference between the measured elastic modulus and the elastic modulus suitable for harvesting is calculated, and the harvest time is determined by dividing the difference by 0.1 To do.

  The analysis determination unit 3 can perform high-accuracy maturity determination by performing the above-described processing. For example, when determining the harvest time from the flowering time of the fruit, a time shift due to a growing individual difference occurs. Since this method can grasp the growth situation immediately before harvesting, it can provide the fruit harvest time more reliably.

  The display unit 4 includes an LCD (Liquid Crystal Display) or the like, and displays information analyzed and determined by the analysis determination unit 3. In addition, various data measured by the measurement unit 2 are displayed. For example, the maturity level is displayed in 15 levels, and the 9th to 13th levels are displayed as appropriate maturity. In addition, the harvest time determined based on the change value of the elastic modulus per day is displayed as the number of days or the date.

  Each component described above is processed centrally by the control unit 5.

  Next, the operation of the maturity determination apparatus 1 will be described with reference to the configuration of the measurement unit 2 shown in FIG. 2 and the flowchart shown in FIG.

  First, before starting the measurement, in step S1, the control unit 5 checks the state of each component unit and initializes variables for arithmetic processing and the like. For example, immediately after the power is turned on, the arm is slid to the most closed state, and initialization for obtaining the diameter is performed. Thereafter, the arm is slid to the extent that the subject 20 is sandwiched and opened.

  In step S2, the first arm 9 and the second arm 10 on the receiving side are slid (step S2), and the subject 20 is sandwiched.

  When the contact sensor 61 detects that the subject 20 is sandwiched in step S3, the control unit 5 enters a state of accepting the oscillation start operation.

  When the oscillation start operation is detected in step S4, the operation after step S5 is started. In step S5, the diameter of the subject 20 is obtained from the movement amount of the arm.

  Next, the oscillation source 6 is operated to apply vibration to the subject 20 (step S6). The vibration sensor 7 detects the vibration of the subject 20 and converts it into an electrical signal. The vibration signal converted into the electrical signal is input to the analysis determination unit 3 (step S7). The analysis determination unit 3 performs extraction processing in the time axis direction including the secondary resonance frequency from the vibration signal in order to facilitate detection of the secondary resonance frequency of the subject 20 whose maturity is to be determined (step S8). Then, FFT analysis is performed to analyze the frequency component of the vibration signal (step S9). Further, mass correction is performed from the diameter of the subject 20 obtained in step S5, and the elastic modulus of the subject 20 is obtained (step S10).

  The analysis determination unit 3 determines appropriateness based on the elastic modulus obtained in step 10 (step S11). The display unit 4 displays the result determined in step S11 and the measurement data of the subject (step S12). After that, the first arm 9 on the oscillation side and the second arm 10 on the vibration receiving side in the measurement unit 2 are slid to a predetermined position to open the arm and prepare for the next measurement ( Step S13).

  By such an operation, the maturity determination apparatus 1 capable of automatic measurement is realized.

  Further, as shown in FIG. 10, the maturity determination apparatus 1 is standardized such as Ethernet, USB (Universal Serial Bus), and flash memory card in order to communicate information with a computer 80 such as a so-called personal computer. The interface 81 is provided. Further, data storage for storing information such as the diameter of the subject 20, the FFT calculation result, the secondary resonance frequency, the elastic modulus, and the determination result measured by the measurement unit 2 with an identification name and a code added to each subject. And a determination data storage unit 83 that stores determination data such as the maturity determined by the analysis determination unit 3.

  Thereby, the maturity determination apparatus 1 can be connected to the computer 80 via the interface 81 and can perform operations such as reading and erasing data stored in the computer 80. Therefore, data such as the effective time region, elastic modulus, and maturity determination of the secondary resonance frequency detection pre-processing described above is loaded into the determination data storage unit 83 from the computer 80 connected via the interface 81, so It is possible to add specimen varieties.

  In addition, the computer 80 analyzes the read data, estimates the harvest time based on the trend of the elastic modulus transition by continuous measurement, and acquires new subject variety data by detailed analysis of the resonance frequency by vibration. Can do.

  11 to 13 show examples of screens based on GUI (Graphical User Interface) displayed on the computer 80. FIG.

  On the screen 100 based on the GUI shown in FIG. 11, an operation for acquiring data from the maturity determination apparatus 1 can be performed. The connection button 101 can be logically connected to the maturity determination apparatus 1 previously connected via an interface such as Ethernet. When this connection button 101 is selected and the connection program is executed, a list of measurement data stored in the data storage unit 82 in the maturity determination apparatus can be displayed in the measurement apparatus data list 102 of the screen 100. Then, by executing the data transfer button 103, the data is transferred from the maturity determination apparatus 103 to the computer 80 and displayed on the computer data list 104. Further, by selecting the delete button 105 and executing the delete program, the data accumulated in the maturity determination apparatus can be deleted.

  The screen 200 based on the GUI shown in FIG. 12 is switched by selecting an individual data area shown on the screen 100. Based on this screen 200, the user can display each data of the subject taken into the computer 80. By selecting a desired identification code from the data list 201 on this screen 200, the measurement data and time-lapse data of the subject can be displayed. In the measurement data display area 202, by selecting desired identification data from the time-dependent data list 203 on which identification codes identified by date and time are displayed, measurement results such as the elastic modulus of the identification data are displayed in the measurement determination result display area 204. And the result of the FFT analysis are displayed in the FFT analysis result area 205. As a result, the user can easily perform data analysis.

  Further, the screen 300 based on the GUI shown in FIG. 13 is switched by selecting the time data area shown on the screen 200. In the temporal data area 301 of the screen 300, the temporal change of desired data selected in the data list 302 is displayed as a graph in the temporal change display area 303. Thereby, the user can confirm the change with time of the elastic modulus. The time change display area 303 shows a harvest time determination area 304 indicating an area of an elastic modulus appropriate for the harvest time. The harvest time determination area 304 is set based on the change over time in the elastic modulus. In addition, a determination display area 305 for displaying a determination result related to the estimated harvest time is provided in the time-dependent data area 301, so that a harvest plan can be easily performed.

  In the present embodiment, the maturity of the subject is determined and the harvest time is estimated. However, the present invention is not limited to this, and the proper maturity time of the subject, that is, the time of eating can also be determined. In this case, the maturity determination apparatus may be provided with a printer or the like, and a sticker indicating the time of eating may be output and attached to the subject.

It is a block diagram which shows the structure of a maturity determination apparatus. It is a schematic diagram which shows the structure of the measurement part in this Embodiment. It is a schematic diagram which shows an example of an oscillation source. It is a schematic diagram which shows an example of an oscillation source. It is a schematic diagram which shows the structure of a vibration sensor. It is a block diagram which shows the structure of an analysis determination part. It is a figure for demonstrating the signal processing in an analysis determination part. It is a figure for demonstrating the signal processing in an analysis determination part. It is a flowchart which shows operation | movement of the maturity determination apparatus in this Embodiment. It is a block diagram which shows the other structure of a maturity determination apparatus. It is a figure which shows an example of the screen displayed on a display apparatus. It is a figure which shows an example of the screen displayed on a display apparatus. It is a figure which shows an example of the screen displayed on a display apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Maturity determination apparatus, 2 Measurement part, 3 Analysis determination part, 4 Display part, 5 Control part, 6 Oscillation source, 7 Vibration sensor, 8 Distance measurement part, 9 1st arm, 10 2nd arm, 11 Slider , 51 sensing element, 52 point contact projection, 53 sensing element receiver, 54 vibration amplification sheet, 55 vibration absorbing material, 56 holder

Claims (7)

An oscillation source that vibrates the subject;
A vibration sensor that includes a detection element that converts strain into an electrical signal, and detects the vibration of the subject when the detection element is distorted by the vibration of the subject;
An acquisition unit for acquiring the diameter of the subject;
The vibration detected by the vibration sensor is analyzed to detect a secondary resonance frequency, the elastic modulus of the subject is calculated based on the secondary resonance frequency and the diameter, and the elastic modulus is calculated based on the elastic modulus. A maturity determination apparatus comprising: an analysis determination unit that determines the maturity of a subject. The vibration sensor includes a protrusion that contacts the subject,
The maturity determination apparatus according to claim 1, wherein the detection element detects vibration of the subject via the protrusion.   The maturity determination apparatus according to claim 1, wherein the analysis determination unit extracts and analyzes vibration in a predetermined time domain from vibration detected by the vibration sensor.   2. The maturity determination apparatus according to claim 1, wherein the oscillation source is a hitting unit that hits the subject. The striking means includes an oscillation head that applies vibration to the subject,
5. The maturity determination apparatus according to claim 4, wherein the oscillation head is fixed to a shaft for driving the oscillation head via an impact absorbing material. A first arm provided with the oscillation source; a second arm provided with the vibration sensor; and a slider that translates the first arm and the second arm;
The maturity according to claim 1, wherein the acquisition unit measures the diameter of the subject by moving the slider by the first arm and / or the second arm and sandwiching the subject. Degree determination device. Harvest time determination means for determining the harvest time based on the change over time in the elastic modulus;
The maturity determination device according to claim 1, further comprising: a harvest time display unit that displays the harvest time.

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