An online nondestructive detection device and method for the maturity of fragrant pear using laser Doppler vibration measurement

Abstract

The invention discloses an online nondestructive detection device and method for the maturity of a fragrant pear using a laser Doppler vibrometer method. The tested fragrant pears are placed on a conveyor belt. When the fragrant pears are transported to a detection position, they are stopped. Then a knocking device releases a knocking ball to stimulate the vibration of the fragrant pear fruit. At the same time, a laser Doppler vibrometer projects laser light onto the vibrating surface of the fragrant pear fruit to detect the fragrant pear. The collected vibration signals are transmitted to a computer through a data acquisition module. The maturity of the fragrant pears is analyzed through software, thereby realizing online nondestructive detection and grading of the maturity of the fragrant pears.

Description

Technical Field

[0001] The invention relates to an online nondestructive detection device and method for the maturity of fragrant pears using laser Doppler vibrometer method. Background Art

[0002] Korla pear is a specialty fruit of Xinjiang. It is well-known at home and abroad for its unique shape, thin skin, tender flesh, rich juice and little residue, rich fragrance, crisp and refreshing taste, and rich nutrition. It is deeply loved by consumers. However, in recent years, in order to seize the market and put it on the market early, merchants have induced fruit farmers to harvest too early, causing the fruit to lose its original sweetness, reduce the taste, and reduce the quality of the fruit. Secondly, since most fruits are harvested in summer and autumn, the temperature is relatively high, and the fruit matures quickly after picking. Especially during the sorting and transportation process, due to over-ripening, the quality of the fruit will be reduced and a large amount of losses will be caused.

[0003] Fruit maturity is an important indicator for measuring fruit quality and grade. Differentiating fruits of different maturity can reduce the loss rate of fruits in logistics links such as picking, packaging, storage, and transportation. During the ripening process, the hardness of fruits continues to soften. Hardness is one of the important indicators for evaluating the maturity of fruits and vegetables and reflecting the internal quality of fruits and vegetables. At different stages of fruit processing, hardness plays an increasingly important role, and it can provide important guidance for fruit picking, sorting, transportation, storage, and sales.

[0004] Laser Doppler vibrometer technology measures the vibration velocity of an object. It is a non-contact measurement technology with high sensitivity, fast dynamic response, insensitivity to lateral vibration interference, and the ability to detect tiny vibrations. Laser Doppler vibrometer technology (LDV) is a non-contact measurement technology that integrates optics, machinery, and electronics to detect the vibration velocity of an object. It has the advantages of high precision, fast dynamic response, large measurement range, and resistance to electromagnetic interference. It can detect tiny amplitudes and accurately measure the vibration response of fruits. For pears of different maturity, their internal organizational structures are different, and the transmission of vibration energy must be different. Therefore, theoretically, the vibration characteristics of pears can be detected using this technology, and the relationship between the vibration characteristics of pears and maturity can be established. Summary of the invention

[0005] 1. Purpose of the present invention.

[0006] The present invention provides an online nondestructive detection device and method for fruit maturity, which can rapidly and nondestructively analyze the maturity of fragrant pears by using laser Doppler vibration measurement technology, thereby realizing the maturity classification of fragrant pears. The system has the characteristics of high automation, fast detection speed and non-contact detection.

[0007] 2. The purpose of the present invention is to adopt the following technical solutions to achieve:

[0008] An online nondestructive testing device for the maturity of fragrant pears:

[0009] It includes a frame, a conveyor belt, a photoelectric sensor, a servo motor, a knocking excitation device and a laser Doppler vibrometer, etc. A conveyor belt with a shading plate on one side is installed on the frame, and a knocking device is installed at the lower middle of the conveyor belt; the servo motor on the frame drives the conveyor belt to move through a sprocket. The laser Doppler vibrometer is placed in front of the conveyor belt in the moving direction.

[0010] The knocking excitation device mainly includes a base, a knocking rod, a knocking ball, an electromagnet, a telescopic electromagnet, a spring, an acceleration sensor, etc. A knocking ball is installed at one end of the knocking rod, an acceleration sensor is installed under the knocking ball, and the other end is connected to the base and can rotate freely. An electromagnet and a telescopic electromagnet are also installed on the base, and the working end of the telescopic electromagnet is connected to the spring.

[0011] The conveyor belt mainly comprises a chain, a support rod, a fruit cup, etc. The support rod passes through the fruit cup and is respectively connected with two chains at both ends to support the fruit.

[0012] The device also includes a PLC, a relay, etc. The photoelectric sensor and the servo motor controller are connected to the PLC, and the electromagnet and the telescopic electromagnet in the knocking device are connected to the PLC through the relay.

[0013] A non-destructive online detection method for the maturity of fragrant pears, the method comprising the following steps:

[0014] (1) The pear is moved from the weighing sensor to the conveyor belt, which then transports the pear to the detection position. The photoelectric sensor is blocked by the shading plate and transmits the signal to the PLC. The PLC controls the servo motor to stop moving, and energizes the electromagnet to attract the knocking rod, and then energizes the telescopic electromagnet to compress the spring to store energy. Then the electromagnet loses power to release the knocking rod, and the knocking ball on the knocking rod knocks the pear. The vibration signal collected by the acceleration sensor on the knocking rod is used as a trigger signal to enable the laser Doppler vibrometer to detect the vibration of the fruit and collect the response signal, which is then transmitted to the computer through the data acquisition module. After the electromagnet loses power, the telescopic electromagnet loses power, causing the spring to return to its initial position. Then the servo motor runs to rotate the conveyor belt and detect the next pear.

[0015] (2) When the knocking device knocks, the knocking signal collected by the accelerometer on the knocking rod is used as a trigger signal, which enables the LDV to detect the fruit and collect vibration signals, which are then transmitted to the computer.

[0016] (3) The computer analyzes the resonance frequency of the pear fruit based on the vibration signal collected by the laser Doppler vibrometer and calculates its damping ratio η:

[0017]

[0018] Where η is the damping ratio, f a and f b The resonant frequencies are f R The corresponding relative amplitude is shifted down 3dB to obtain the frequency values ​​corresponding to the two points on the left and right, f R is the resonant frequency.

[0019] The resonant frequency collected by the LDV is combined with the mass collected by the weighing sensor to calculate its elasticity index EI:

[0020]

[0021] Among them, f R is the resonance frequency, m is the mass of the tested pear, and EI is the elasticity index.

[0022] The damping ratio is used to analyze the soluble solid content of the fragrant pear, the elasticity index is used to analyze the hardness of the fragrant pear, and the maturity of the fragrant pear is judged by referring to the national standards in this field.

[0023] 3. The beneficial effects of the present invention are:

[0024] The invention discloses a device for performing online detection of the maturity of fragrant pears by using a laser Doppler vibration measurement method, and can accurately, rapidly and non-destructively detect the maturity of fragrant pears and grade them. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a three-dimensional diagram of the overall structure of the present invention.

[0026] Figure 2 It is a three-dimensional diagram of the structure of the striking device of the present invention.

[0027] Figure 3 This is a three-dimensional diagram of the conveyor belt structure. DETAILED DESCRIPTION

[0028] A non-destructive online detection device for the maturity of fragrant pears:

[0029] The machine comprises a frame 2, a conveyor belt 4, a photoelectric sensor 6, a servo motor 7, a knocking excitation device 5 and a laser Doppler vibrometer 1. The frame 2 is provided with a conveyor belt 4 with a shading plate on one side, and a knocking device 5 is provided at the lower middle part of the conveyor belt 4. The servo motor 7 on the frame 2 drives the conveyor belt 4 to move through the sprocket 3. The laser Doppler vibrometer 1 is placed in front of the conveyor belt 4 in the moving direction.

[0030] The knocking excitation device 5 mainly includes a base 54, a knocking rod 53, a knocking ball 51, an electromagnet 52, a telescopic electromagnet 55, a spring 56, an acceleration sensor 57, etc. The knocking ball 51 is installed at one end of the knocking rod 53, and the acceleration sensor 57 is installed below the knocking ball 51. The other end is connected to the base 54 and can rotate freely. The electromagnet 52 and the telescopic electromagnet 55 are also installed on the base 54, and the working end of the telescopic electromagnet 55 is connected to the spring 56.

[0031] The conveyor belt mainly includes a chain 43, a support rod 42, a fruit cup 41, etc. The support rod 42 passes through the fruit cup 41 and is connected to two chains 43 at both ends to support the fruit.

[0032] The device also includes a PLC, a relay, etc. The photoelectric sensor 6 and the controller of the servo motor 7 are connected to the PLC, and the electromagnet 52 and the telescopic electromagnet 55 in the knocking device 5 are connected to the PLC through the relay.

[0033] A non-destructive online detection method for the maturity of fragrant pears, the method comprising the following steps:

[0034] (1) The fragrant pear is moved from the weighing sensor to the conveyor belt 4, and then the conveyor belt 4 transports the fragrant pear to the detection position. The photoelectric sensor 6 is blocked by the shading plate and transmits the signal to the PLC. The PLC controls the servo motor 7 to stop moving, and the electromagnet 52 is energized to attract the knocking rod 53, and then the telescopic electromagnet 55 is energized to compress the spring 56 to store energy. Then the electromagnet 52 loses power and releases the knocking rod 53, and the knocking ball 51 on the knocking rod 53 knocks the fragrant pear. The vibration signal collected by the acceleration sensor 57 on the knocking rod 53 is used as a trigger signal to make the laser Doppler vibrometer 1 detect the vibration of the fruit and collect the response signal, which is then transmitted to the computer through the data acquisition module. After the electromagnet 52 loses power, the telescopic electromagnet 55 loses power, causing the spring 56 to return to the initial position. Then the servo motor 7 is operated to rotate the conveyor belt to detect the next fragrant pear.

[0035] (2) When the knocking device 5 knocks, the knocking signal collected by the accelerometer 57 on the knocking rod 53 is used as a trigger signal, so that the laser Doppler vibrometer 1 detects the fruit and collects the vibration signal, which is then transmitted to the computer.

[0036] (3) The computer analyzes the resonance frequency of the pear fruit based on the vibration signal collected by the laser Doppler vibrometer 1 and calculates its damping ratio η:

[0037]

[0038] Where η is the damping ratio, f a and f bThe resonant frequencies are f R The corresponding relative amplitude is shifted down 3dB to obtain the frequency values ​​corresponding to the two points on the left and right, f R is the resonant frequency.

[0039] The resonant frequency collected by the LDV is combined with the mass collected by the weighing sensor to calculate its elasticity index EI:

[0040]

[0041] Among them, f R is the resonance frequency, m is the mass of the tested pear, and EI is the elasticity index.

[0042] The soluble solid content of the fragrant pear is analyzed by the damping ratio, the hardness of the fragrant pear is analyzed by the elasticity index, and the maturity of the fragrant pear is judged by referring to the national standards in this field.

[0043] 3. The beneficial effects of the present invention are:

[0044] The invention discloses an online detection system for the maturity of fragrant pears using the laser Doppler principle, which can accurately, rapidly and non-destructively detect the maturity of fragrant pears and grade them.

Claims

1. A method for nondestructive online detection of pear maturity based on an online nondestructive detection device for pear maturity, characterized in that: The on-line non-destructive detection device for the maturity of fragrant pears comprises a frame (2), a conveyor belt (4), a photoelectric sensor (6), a servo motor (7), a knocking excitation device (5) and a laser Doppler vibrometer (1); a conveyor belt (4) having a light shielding plate on one side is installed on the frame (2), and the knocking excitation device (5) is installed at the lower middle part of the conveyor belt (4); the servo motor (7) on the frame (2) drives the conveyor belt (4) to move via a sprocket (3), and the laser Doppler vibrometer (1) is placed in front of the conveyor belt (4) in the moving direction; The knocking excitation device (5) comprises a base (54), a knocking rod (53), a knocking ball (51), a first electromagnet (52), a telescopic electromagnet (55), a spring (56), and an acceleration sensor (57). The knocking ball (51) is installed at one end of the knocking rod (53), the acceleration sensor (57) is installed below the knocking ball (51), and the other end is connected to the base (54) and can rotate freely. The first electromagnet (52) and the telescopic electromagnet (55) are also installed on the base (54), and the working end of the telescopic electromagnet (55) is connected to the spring (56). The conveyor belt comprises a chain (43), a support rod (42), and a fruit cup (41); the support rod (42) passes through the fruit cup (41) and is connected to two chains (43) at both ends to support the fruit; The online nondestructive testing device further comprises a PLC and a relay, the photoelectric sensor (6) and the controller of the servo motor (7) are connected to the PLC, and the first electromagnet (52) and the telescopic electromagnet (55) in the knocking excitation device (5) are connected to the PLC via the relay; The online detection method comprises the following steps: The pear is moved from the weighing sensor to the conveyor belt, and then the conveyor belt transports the pear to the detection position. The photoelectric sensor is blocked by the shading plate and transmits the signal to the PLC. The PLC controls the servo motor to stop moving, and energizes the first electromagnet to attract the knocking rod, and then energizes the telescopic electromagnet to compress the spring to store energy; then the first electromagnet loses power to release the knocking rod, and the knocking ball on the knocking rod knocks the pear; the vibration signal collected by the acceleration sensor on the knocking rod is used as a trigger signal to enable the laser Doppler vibrometer to detect the vibration of the fruit and collect the response signal, which is then transmitted to the computer through the data acquisition module; after the first electromagnet loses power, the telescopic electromagnet loses power to make the spring return to the initial position; then the servo motor runs to rotate the conveyor belt to detect the next pear; The computer analyzes the resonance frequency of the pear fruit based on the vibration signal collected by the laser Doppler vibrometer and calculates its damping ratio η: Where η is the damping ratio, f a and f b The resonant frequencies are f R The corresponding relative amplitude is shifted down 3dB to obtain the frequency values ​​corresponding to the two points on the left and right, f R is the resonant frequency; The resonant frequency collected by the laser Doppler vibrometer is combined with the mass collected by the weighing sensor to calculate its elastic index EI: Among them, f R is the resonance frequency, m is the mass of the tested pear, and EI is the elasticity index; The soluble solids content of the pear can be analyzed from the damping ratio, and the hardness of the pear can be analyzed from the elasticity index.

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