Quality measuring device, work robot, and quality measurement method

Abstract

A device according to one embodiment of the present disclosure is a device for measuring the quality of agricultural crops using light in a predetermined wavelength band, the device comprising a header portion having a light projecting portion and a light receiving portion, and a main body portion having a distal end portion to which the header portion is connected via a coupling portion, wherein the coupling portion is configured from a flexible joint that supports the header portion such that the inclination of the header portion can vary in accordance with an external force.

Description

Quality Measurement Device, Working Robot, and Quality Measurement Method

[0001] The present disclosure relates to a quality measurement device, a working robot, and a quality measurement method. This application claims priority based on Japanese Application No. 2024-228469 filed on December 25, 2024, and incorporates all the descriptions set forth in the above-mentioned Japanese application.

[0002] Patent Document 1 describes a device that uses light in a predetermined wavelength band to nondestructively measure the quality of agricultural products such as fruits. In the quality measurement device of Patent Document 1, near-infrared light is irradiated onto the agricultural product to be measured, and the quality such as the sugar content or acidity of the agricultural product is measured based on the spectral intensity for each wavelength of the reflected light from the agricultural product.

[0003] Japanese Patent Application Laid-Open No. 2002-116141

[0004] An apparatus according to one aspect of the present disclosure is an apparatus that measures the quality of agricultural products using light in a predetermined wavelength band, and includes a header unit having a light projecting unit and a light receiving unit, and a main body unit having a tip end portion to which the header unit is connected via a connecting portion. The connecting portion is constituted by a flexible joint that supports the header unit such that the inclination of the header unit becomes variable according to an external force.

[0005] Embodiments of the present disclosure can be implemented by an apparatus, a system, a method, an integrated circuit, a computer program, or a non-transitory computer-readable recording medium, or any combination thereof. The nature of the recording medium may be either volatile or non-volatile. The apparatus may be composed of a plurality of individual apparatuses. When composed of a plurality of individual apparatuses, they may be arranged in one housing or separated and arranged in two or more separate housings.

[0006] FIG. 1 is a perspective view showing an example of the overall configuration of an agricultural work system. FIG. 2 is a cross-sectional view showing an example of the internal configuration of a quality measurement device. FIG. 3 is a flowchart showing an example of quality measurement processing. FIG. 4 is an explanatory view showing an example of variations in the morphological changes of the connecting portion. FIG. 5 is a cross-sectional view showing another example of the internal configuration of a quality measurement device. FIG. 6 is a perspective view of a quality measurement device according to another disclosure.

[0007] <Problems this disclosure aims to solve> In quality measurement using reflected light from agricultural products, the quality value is determined based on the spectral intensity of each wavelength of reflected light, so the accuracy decreases when ambient light is mixed in. In particular, in outdoor measurements such as in fields, ambient light is more likely to be mixed in than indoors, so the accuracy may decrease even more. However, Patent Document 1 does not consider the problem of accuracy reduction due to ambient light. In view of these conventional problems, this disclosure aims to suppress the decrease in accuracy of a quality measurement device that uses light in a predetermined wavelength band.

[0008] <Effects of this disclosure> According to this disclosure, it is possible to suppress the decrease in accuracy of a quality measurement device that uses light in a predetermined wavelength band.

[0009] <Outline of Embodiments of the Disclosure> The outlines of embodiments of the disclosure are listed below. (1) An apparatus according to one aspect of this embodiment is an apparatus for measuring the quality of agricultural products using light in a predetermined wavelength band, comprising a header section having a light-emitting section and a light-receiving section, and a main body section having a tip section to which the header section is connected via a connecting section, wherein the connecting section is composed of a flexible joint that supports the header section such that the inclination of the header section is variable in response to an external force.

[0010] In the quality measuring device of this embodiment, the connecting part is made of a flexible joint that supports the header part so that the inclination of the header part is variable in response to external force. For example, by moving the header part in a direction that brings it closer to the crop and pressing it against the crop, the header part can be made to face the crop almost directly. Therefore, the amount of ambient light entering the light receiving part can be reduced, and the decrease in accuracy due to ambient light mixing with reflected light can be suppressed.

[0011] (2) In the quality measuring device described in (1) above, the flexible joint may include a plurality of elastic members (for example, coil springs or rubber rod-shaped members) arranged to surround the central part of the header.

[0012] This method provides a more flexible and cushioned design compared to using the plastic members described later. Consequently, a quality measuring device is obtained in which the surface of agricultural products is less likely to be damaged even when the header is pressed against them.

[0013] (3) In the quality measuring device described in (1) above, the flexible joint may include a plurality of plastic members (for example, an arm member with a ball joint) arranged to surround the central part of the header.

[0014] In this way, compared to the case where the aforementioned elastic member is used, a flexible performance that is less prone to wobbling when subjected to external forces can be obtained. Therefore, a quality measuring device can be obtained that can more stably ensure that the header part is directly facing the agricultural product.

[0015] (4) In the quality measuring devices described in (1) to (3) above, the crop may be grapes. In this case, a decrease in the accuracy of quality measurement for grapes can be suppressed.

[0016] (5) Another embodiment of this invention is a work robot comprising a moving device and a robot arm mounted on the moving device, wherein one of the quality measuring devices described in (1) to (4) above is connected to the tip of the robot arm.

[0017] With the work robot of this embodiment, the quality measuring device of this embodiment is connected to the tip of the robot arm of the work robot, so that a decrease in the accuracy of the quality measurement performed by the work robot can be suppressed.

[0018] (6) The method according to this embodiment is a quality measurement method performed by the apparatus described in (1) to (4) above, and includes the steps of pressing the header portion against the crop and emitting and receiving light while the header portion is pressed against the crop.

[0019] According to the quality measurement method of this embodiment, since the header portion supported by the flexible joint is pressed against the crop while light is emitted and received, light is emitted and received with the header portion almost directly facing the crop. Therefore, the amount of ambient light entering the light receiving portion can be reduced, and the decrease in accuracy due to ambient light mixing with reflected light can be suppressed.

[0020] <Details of Embodiments of the Disclosure> Details of embodiments of the disclosure will be described below with reference to the drawings. At least some of the embodiments described below may be combined in any way.

[0021] [Overall Configuration of the Agricultural System] Figure 1 is a perspective view showing an example of the overall configuration of the agricultural system 200. As shown in Figure 1, the agricultural system 200 of this embodiment includes a work robot 10 capable of traveling on a field 210, a communication device 20, and a server 30. In this embodiment, the crop 40 in the field 210 is grapes, which are the raw material for wine, and the field 210 is a vineyard for cultivating grapes 40. In the vineyard 210, the same variety or different varieties of grapes 40 may be cultivated.

[0022] The work robot 10 is connected to the communication device 20 via a wireless LAN or the like. The communication device 20 is a wireless router that has, for example, the communication function of a wireless LAN (Local Area Network) and the communication function of a mobile communication system such as LTE (Long Term Evolution) or 5G. Therefore, the work robot 10 can communicate with the server 30 via local communication with the communication device 20 and public communication via the wireless base station 50 and the public communication network 60.

[0023] Server 30 is a management server that provides predetermined farming support services to users (not shown) who manage the field 210. The public communication network 60 includes the internet, and user terminals (not shown) are connected to the public communication network 60. In response to service requests transmitted from user terminals, Server 30 issues commands for the work to be performed by the work robot 10, and collects work results and notifies the user terminals of them.

[0024] [Example of a work robot configuration] As shown in Figure 1, the work robot 10 comprises a mobile device 11 and a robot arm 12 mounted on the mobile device 11. The mobile device 11 is, for example, an electric vehicle and has a driving body 13 and a chassis 14 that includes a plurality (for example, four) of wheels that constitute the lower part of the driving body 13. However, the drive system of the chassis 14 may be a crawler system, a hybrid system having both wheels and crawlers, or a walking system that walks on two or more legs.

[0025] The robot arm 12 comprises a manipulator 15 located at the front upper part of the travel body 13, and an end effector 16 detachably attached to the tip of the manipulator 15. The manipulator 15 is composed of, for example, a multi-joint arm including multiple joints that changes the three-dimensional position of the end effector 16. Inside the travel body 13 are control devices (not shown) for automatically or remotely controlling the chassis 14 of the work robot 10 and the robot arm 12, respectively.

[0026] Automatic operation of the work robot 10 is achieved by an automatic driving control program installed in the control unit. Remote operation of the work robot 10 is performed by operation input from a user terminal that communicates with the work robot 10 via the server 30. Position control in the above automatic and remote operation is performed based on sensing results from cameras and LiDAR (Laser Imaging Detection and Ranging) installed on the mobile device 11 and robot arm 12.

[0027] The end effector 16 is a device that performs predetermined tasks on crops 40, and performs the predetermined tasks while being positioned near the target object by the manipulator 15. Multiple end effectors 16 are provided for each type of task. Types of tasks include, for example, harvesting, pruning, watering, fertilizing, pesticide spraying, condition detection, photography, pest control, and equipment charging. Therefore, the user can have the work robot 10 perform the above-mentioned various tasks in the field 210.

[0028] The end effector 16 includes a quality measurement device (hereinafter referred to as the "quality measurement device") 70, which is a type of condition detection for agricultural products 40. The object of quality measurement is not limited to grapes 40, but may also be other fruits or vegetables. The quality measurement device 70 is a device that measures the quality of agricultural products 40 non-contact using light in a predetermined wavelength band (for example, near-infrared light). Measurable quality includes, for example, sugar content, acidity, pH, and polyphenol content.

[0029] [Internal Configuration of Quality Measurement Device] Figure 2 is a cross-sectional view showing an example of the internal configuration of the quality measurement device 70. As shown in Figure 2, the quality measurement device 70 is a device that irradiates crops 40 with near-infrared light UO and determines the components of crops 40 using the spectral intensity of reflected light DO at each wavelength. Reflected light DO includes directly reflected light reflected from the surface of crops 40 and indirectly reflected light that is scattered inside crops 40 before returning.

[0030] The quality measuring device 70 of this embodiment comprises, as its main components, a header section 71 having the function of transmitting and receiving near-infrared light UO and reflected light DO, a connecting section 72 that can flexibly connect the header section 71 to the main body section 73, and a main body section 73 having a tip to which the header section 71 is connected via the connecting section 72.

[0031] (Header section configuration) The header section 71 has a ring-shaped retaining frame 74, a light-emitting / receiving section 75, and a protective plate 76. The retaining frame 74 is a frame material whose outer circumference, as viewed from the grape 40 side, is approximately circular or elliptical. The light-emitting / receiving section 75 and the protective plate 76 are circular or elliptical plate materials whose outer circumference, as viewed from the grape 40 side, is slightly larger than the inner diameter of the retaining frame 74.

[0032] The light-emitting and light-receiving unit 75 includes a circuit board 77 with a perforated center, a light-receiving element 78 mounted in the center, and a plurality of light-emitting elements 79 mounted on the surface of the circuit board 77. The outer edge of the circuit board 77 is fitted into a circumferential groove formed on the inner surface of the retaining frame 74. The outer edge of the protective plate 76 is fitted into another circumferential groove formed on the inner surface of the retaining frame 74. The protective plate 76 is made of light-transmitting glass or synthetic resin and functions as a shielding member that protects the surface side (left side in Figure 2) of the light-emitting and light-receiving unit 75 from the external environment.

[0033] The light-emitting element 79 is a component that functions as a light-emitting part of the near-infrared light UO, and is made of, for example, an LED (Light Emitting Diode) that emits near-infrared light. Multiple light-emitting elements 79 are mounted on the surface of the circuit board 77 (the left side in Figure 2). The multiple light-emitting elements 79 are arranged at predetermined intervals in the circumferential direction along, for example, concentric circles or concentric ellipses with a diameter smaller than the circuit board 77.

[0034] The light-receiving element 78 is a component that functions as a light-receiving part for reflected light DO, and consists of, for example, one optical fiber or a bundle of multiple optical fibers. The light-receiving element 78 is mounted in the center of the circuit board 77 such that the length direction of the optical fiber is oriented in the direction normal to the circuit board 77. The light-receiving surface of the light-receiving element 78 (specifically, the tip surface of the optical fiber) is exposed on the surface side of the circuit board 77.

[0035] A pressure-sensitive sensor 80 is provided on the surface of the retaining frame 74 (the left side in Figure 2). The pressure-sensitive sensor 80 consists of, for example, a pressure-sensitive sheet formed in a ring shape that is almost the same as the surface of the retaining frame 74, and is attached to the surface with an adhesive or the like. The pressure-sensitive sensor 80 is a sensor that monitors the pressure caused by contact with an object such as agricultural products 40. Accordingly, the pressure-sensitive sensor 80 transmits a pressure signal, which is an electrical signal corresponding to the contact pressure on itself, to the controller 84 described later.

[0036] (Configuration of the main body) The main body 73 comprises a hollow cylindrical body 81 having a circular or elliptical cross-section, and a group of quality measurement circuits housed inside the hollow cylindrical body 81. This group of circuits includes a power supply circuit 82, a spectrometer 83, and a controller 84. A connector 85 is provided on the bottom wall of the hollow cylindrical body 81. The connector 85 is a standard connector that integrates digital communication and power supply into a single cable, such as USB (Universal Serial Bus).

[0037] The power supply circuit 82 is, for example, a DC / DC converter, which converts the DC supplied from the connector 85 into a predetermined voltage and supplies the converted DC to the spectrometer 83 and the controller 84. The spectrometer 83 is a circuit module that spectrally separates the input light from the photodetector 78 into predetermined wavelength bands and generates an electrical signal (hereinafter referred to as "intensity signal") representing the light intensity of each wavelength band. The intensity signals generated by the spectrometer 83 are output to the controller 84.

[0038] The controller 84 generates quality data from the intensity signal input from the spectrometer 83 and sends the generated quality data to the connector 85. The quality data is digital information including the intensity value for each spectrally separated spectrum and is transmitted to the control device of the mobile device 11. The control device of the mobile device 11 uses the quality data received from the controller 84 to calculate quality values ​​such as the sugar content and acidity of the crop 40. Alternatively, the controller 84 may calculate the quality values ​​based on the quality data.

[0039] The controller 84 is capable of serial communication with other circuits or elements included in the quality measuring device 70, and controls the operation of these other circuits or elements through this serial communication. Specifically, when a predetermined start condition for quality measurement (for example, step S13 in Figure 3) is met, the controller 84 instructs the control IC (not shown) on the circuit board 77 to emit light from the light-emitting element 79, or instructs the spectrometer 83 to output an intensity signal.

[0040] (Configuration of the connecting section) The connecting section 72 is composed of a flexible joint 91 that supports the header section 71 so that the inclination of the header section 71 can be varied in response to external forces. The flexible joint 91 is composed of, for example, a plurality of coil springs 91A. The plurality of coil springs 91A have the same elastic constant and at least three are provided, and are arranged at equal intervals in the circumferential direction on the back side of the retaining frame 74.

[0041] The base end (right end in Figure 2) of each coil spring 91A is fixed to the flange of the hollow cylindrical body 81, and the tip (left end in Figure 2) of each coil spring 91A is fixed to the back surface of the retaining frame 74. Each of the multiple coil springs 91A fixed as described above elastically deforms in response to the external force acting on the header portion 71, so that the header portion 71 is flexibly connected to the main body portion 73. The connecting portion 72 further has a flexible cover 92 made of, for example, a rubber bellows cylindrical material.

[0042] The base edge of the flexible cover 92 (the right edge in Figure 2) is fixed to the front edge of the hollow cylinder 81, and the front edge of the flexible cover 92 (the left edge in Figure 2) is fixed to the back edge of the retaining frame 74. As the flexible cover 92 is fixed in this manner, it deforms to follow the tilt of the retaining frame 74, so even if the header portion 71 is tilted by an external force, the gap between the hollow cylinder 81 and the retaining frame 74 is always closed off from the outside air.

[0043] [Contents of Quality Measurement Process] Figure 3 is a flowchart showing an example of the quality measurement process performed by the controller 84. As shown in Figure 3, the controller 84 monitors whether the pressure-sensitive signal is above a predetermined threshold (step S11), and if it is above the threshold, it sends a "pressure request" to the control device of the mobile device 11 (step S12). A "pressure request" is a control message that requests the control device of the mobile device 11 to perform a "position change process" of the quality measuring device 70.

[0044] The "position change process" refers to the process of moving the quality measurement device 70 by a "predetermined distance" in the direction of "approaching the measurement target" from the current position where a pressing request is received. The above-mentioned "direction of approaching the measurement target" is, for example, a vector that satisfies the following conditions. Condition 1: It is parallel to the current axial direction of the end effector 16. Condition 2: The distance between the current position of the representative point of the end effector 16 (for example, the center point of the header unit 71) and the representative point of the agricultural crop 40 (for example, the centroid of the agricultural crop 40) decreases.

[0045] The above-mentioned "predetermined distance" is, for example, a set value of the distance determined according to the type of the measurement target. In the case of the grape 40, a set value within the range of, for example, 10 mm to 30 mm can be adopted as the predetermined distance. The reason is that when the predetermined distance is less than 10 mm, the inclination of the header unit 71 does not change much, so the so-called facing effect described later cannot be expected. Also, when the predetermined distance exceeds 30 mm, there is a possibility that the grape 40 will be overloaded and threshing or detaching will occur.

[0046] Next, the controller 84 determines whether it has received a "pressing response" from the control device of the moving device 11 (step S13). The "pressing response" is a control message in which the control device of the moving device 11 notifies the controller 84 of the completion of the above-mentioned position change process. If the determination result in step S13 is affirmative, the controller 84 generates light emission and spectral intensity (step S14). Specifically, the controller 84 instructs the control IC of the circuit board 77 to emit light from the light emitting element 79, and instructs the spectroscope 83 to output an intensity signal.

[0047] Next, the controller 84 generates and transmits quality data (step S15). Specifically, the controller 84 generates quality data based on the intensity signal, and transmits the generated quality data to the control device of the moving device 11. When the transmission of the quality data is completed, after the controller 84 stops generating light emission and spectral intensity (step S16), it ends the process. Specifically, the controller 84 instructs the control IC of the circuit board 77 to turn off the light emitting element 79, and instructs the spectroscope 83 to stop operating or pause the output of the intensity signal (sleep).

[0048] If the determination result in step S13 is negative, the controller 84 notifies the control device of the mobile device 11 that measurement is impossible (step S17), and then ends the process. The reason is that when no pressing response is received, it is presumed that the end effector 16 (quality measurement device 70) has not moved by a predetermined distance and the header unit 71 is not facing the agricultural crop 40 directly, so accurate quality measurement may not be achievable.

[0049] [Variations in morphological changes] FIG. 4 is an explanatory diagram showing an example of variations in the morphological changes of the connecting portion 72. In FIG. 4, "C" represents the center point of the light transmitting / receiving surface of the header unit 71, and "N" represents the normal line of the light transmitting / receiving surface passing through the center point C.

[0050] The "first state" in FIG. 4 shows a state in which the contact pressure from the grape 40 acts on the portion above the center point C in the header unit 71 as a result of the position change process of the quality measurement device 70. The "second state" in FIG. 4 shows a state in which the contact pressure from the grape 40 acts on the portion below the center point C in the header unit 71 as a result of the position change process of the quality measurement device 70.

[0051] In the first state, since the contact pressure acts on the upper half portion of the header unit 71, the flexible joint 91 (connecting portion 72) undergoes a morphological change such that the coil spring 91A located above the center point C contracts and the coil spring 91A located below the center point C extends. As a result, the header unit 71 tilts so that the normal line N faces upward. Therefore, the center point C of the header unit 71 approaches the grains of the grape 40 more than in the case where no tilt occurs, and the header unit 71 faces almost directly the lower half portion of the grape bunch 40 of the grape 40 (the facing effect associated with the upward tilt).

[0052] In the second state, the contact pressure acts on the lower half of the header portion 71, causing the flexible joint 91 (connecting portion 72) to change shape so that the coil spring 91A located below the center point C compresses and the coil spring 91A located above the center point C extends. As a result, the header portion 71 tilts so that the normal N points downward. Consequently, the center point C of the header portion 71 is closer to the grapes 40 than when there is no tilt, and the header portion 71 is almost directly facing the upper half of the bunch of grapes 40 (direct facing effect due to downward tilt).

[0053] Thus, according to the quality measuring device 70 of this embodiment, the header portion 71 faces the bunch of grapes 40 directly due to the change in shape of the flexible joint 91 composed of multiple coil springs 91A, thereby reducing the amount of ambient light entering the light receiving element 78. Consequently, the influence of ambient light on the light of each wavelength band contained in the reflected light DO is reduced, and the decrease in accuracy due to the inclusion of ambient light is suppressed.

[0054] In the quality measuring device 70 of this embodiment, the components of the flexible joint 91 can be any elastic member that deforms in response to the contact pressure from the crops 40. Therefore, the flexible joint 91 is not limited to the coil spring 91A shown in the figure, but may be composed of, for example, a plurality of rubber rod-shaped members, or it may be a hybrid configuration including both the coil spring 91A and rubber rod-shaped members.

[0055] [Modified Flexible Joint] Figure 5 is a cross-sectional view showing another example of the internal configuration of the quality measuring device 70. As shown in Figure 5, in the other example of the quality measuring device 70, the flexible joint 91 is composed of multiple arm members 91B with ball joints. The multiple arm members 91B are of the same length and at least three are provided, and are arranged at equal intervals in the circumferential direction on the back side of the holding frame 74.

[0056] The base end (right end in Figure 5) of each arm member 91B is fixed to the flange of the hollow cylindrical body 81, and the tip (left end in Figure 5) of each arm member 91B is fixed to the back surface of the retaining frame 74. The arm member 91B includes, for example, an intermediate link 93 having ball portions at both ends and a pair of end links 94 having cup portions into which the ball portions are press-fitted (friction-fitted). This arm member 91B is a type of plastic member that maintains its state after being bent by an external force.

[0057] As shown in Figure 5, the flexible joint 91 can be made up of not only elastic members such as a coil spring 91A, but also plastic members such as an arm member 91B with a ball joint. Furthermore, the flexible joint 91 may have a hybrid configuration that includes both elastic and plastic members.

[0058] [Other Disclosures] Figure 6 is a perspective view of a quality measuring device 70 according to other disclosures. The quality measuring device 70 in Figure 6 does not have a connecting portion 72 made up of a flexible joint 91, but is characterized by the shape of the header portion 71. Its characteristic is that the wall portion of the header portion 71 includes a pair of left and right curved wall portions 71L and 71R that protrude towards the tip side of the light transmitting and receiving portion 75.

[0059] The curved wall portions 71L and 71R are symmetrical and formed in a convex curve that gradually tapers towards the tip when viewed from the side. The bases of the curved wall portions 71L and 71R are smoothly continuous, forming a concave curve when viewed from above. By forming curved wall portions 71L and 71R of this shape on the header portion 71, the crops 40 can be easily positioned by fitting them between the curved wall portions 71L and 71R. Consequently, it becomes easier to maintain a close proximity between the crops 40 and the light-emitting / receiving unit 75, leading to stabilization of the measurement work.

[0060] [Other Modifications] The embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is not limited to the embodiments described above, and includes all modifications within the scope of equivalence to the configurations described in the claims.

[0061] 10 Working robot 11 Mobile device 12 Robot arm 13 Driving body 14 Chassis 15 Manipulator 16 End effector 20 Communication device 30 Server 40 Agricultural product (grapes) 50 Wireless base station 60 Public communication network 70 Quality measurement device 71 Header section 72 Connecting section 73 Main body section 74 Holding frame 75 Transmitting / receiving section 76 Protective plate 77 Circuit board 78 Light receiving element (light receiving section) 79 Light-emitting element (light-emitting section) 80 Pressure sensor 81 Hollow cylinder 82 Power supply circuit 83 Spectrometer 84 Controller 85 Connector 91 Flexible joint 91A Coil spring 91B Arm member 92 Flexible cover 93 Intermediate link 94 End link 200 Agricultural work system 210 Field (vineyard)

Claims

1. A device for measuring the quality of agricultural products using light in a predetermined wavelength band, comprising: a header section having a light-emitting section and a light-receiving section; and a main body section having a tip section to which the header section is connected via a connecting section, wherein the connecting section is composed of a flexible joint that supports the header section such that the inclination of the header section is variable in response to external forces.

2. The quality measuring device according to claim 1, wherein the flexible joint includes a plurality of elastic members arranged to surround the central part of the header portion.

3. The quality measuring device according to claim 1, wherein the flexible joint includes a plurality of plastic members arranged to surround the central part of the header portion.

4. The quality measuring device according to any one of claims 1 to 3, wherein the crop is grapes.

5. A work robot comprising a mobile device and a robot arm mounted on the mobile device, wherein a quality measuring device according to any one of claims 1 to 3 is connected to the tip of the robot arm.

6. A method for measuring the quality of agricultural products, performed by an apparatus for measuring the quality of agricultural products using light in a predetermined wavelength band, the apparatus comprising: a header section having a light-emitting section and a light-receiving section; and a main body section having a tip section to which the header section is connected by a flexible joint that supports the header section such that the inclination of the header section is variable in response to an external force, the method comprising: pressing the header section against the agricultural product; and performing light emission and light reception while the header section is pressed against the agricultural product.

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