Strawberry flexible clamping device and contact information sensing method

Abstract

The invention relates to a strawberry flexible clamping device and a contact information sensing method, and belongs to the technical field of clamping devices and contact information sensing methods.The strawberry flexible clamping device comprises an end effector and two visual tactile sensing clamping hands, and each visual tactile sensing clamping hand comprises a fixing base, a camera, a fixing cylinder, a lens and an elastic piece; the two fixed seats are respectively fixed on the two connecting seats; the two cameras are respectively fixed on the end surfaces of the two fixed seats; one ends of the two fixed cylinders are respectively fixed on the end surfaces, close to each other, of the two fixed seats; one side surfaces of the two lenses are respectively sealed at the other ends of the two fixed cylinders; one side faces of the two elastic pieces are fixed to the other side faces of the two lenses respectively. The two connecting seats of the end effector are used for driving the two fixing seats to get close to each other or get away from each other, and the lenses and the elastic pieces are fixed to the other ends, close to each other, of the two fixing cylinders fixed to the two fixing seats, so that strawberries can be flexibly clamped through the elastic pieces, and damage to the strawberries is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of clamping devices and contact information sensing methods, and in particular to a flexible strawberry clamping device. Background Art

[0002] Strawberries contain many important dietary ingredients, including vitamins, minerals, folic acid and fiber, and are a rich source of phytochemical compounds, mainly represented by polyphenols. While being beneficial to the human body, strawberries also play an important role in economic crops and are widely consumed in the form of fresh strawberries or processed forms such as jams and juices. However, due to the exposed and soft pseudo-fruits, strawberries are very susceptible to damage during the harvesting process. Nowadays, most strawberry picking is still mainly done by hand. With the continuous increase in strawberry production and labor costs, efficient and rapid automated mechanized picking will gradually replace manual picking. Although many teams have developed rigid grippers for picking strawberries, rigid grippers are in a blind spot in terms of force control and information perception such as the clamping area, which poses a greater risk of damage to strawberry grasping. It can be seen that two visual-tactile sensing grippers and tactile feedback are essential for picking strawberries or fruits that are exposed, soft and fragile, similar to strawberry fruits.

[0003] Strawberries are typical soft and fragile fruits. Do not apply too much force when grasping them to avoid crushing or breaking them. The surface of strawberries is smooth and sensitive, and the slightest squeezing or contact will leave indentations or damage. Therefore, the robot needs to have a soft grasping method when grasping strawberries, usually using a flexible clamp or a force control system with perception capabilities. At the same time, each strawberry is different in size and shape, and has irregular and tiny protrusions on the surface, so the robot needs to be able to adapt to different shapes. In addition, strawberries grow outdoors or in greenhouses, and factors such as ambient light and humidity may affect the visual sensor or grasping accuracy, so the grasping system needs to have a certain degree of environmental adaptability. Summary of the invention

[0004] In summary, the main feature of strawberry grasping is the soft and fragile fruit characteristics, which requires the robot to have high flexibility, intelligent force control and accurate visual perception system. Therefore, the present invention aims to provide a strawberry flexible clamping device and contact information perception method based on visual tactile sensing, which applies visual tactile sensing technology to the design of strawberry grippers, and uses the flexibility of the contact surface elastic body and the high-resolution information extraction and feedback capabilities to perceive the tactile information of soft and fragile strawberries in real time, i.e., the contact area and contact normal force of the flexible gripper and the strawberry, and implement stable and lossless strawberry clamping, which meets the structural design and functional requirements of the above-mentioned strawberry grasping robot, and provides a theoretical basis for the flexible clamping device of the strawberry harvesting robot.

[0005] The object of the present invention is to provide a flexible strawberry clamping device, comprising: an end effector and a visual-tactile sensing gripper, wherein the end effector is provided with two connecting seats that can be close to or away from each other; the visual-tactile sensing grippers are two relatively arranged and each comprises a fixing seat, a camera, a fixing tube, a lens and an elastic member, the two fixing seats are respectively fixed on the two connecting seats; the two cameras are respectively fixed on the end faces of the two fixing seats that are close to each other; the two fixing tubes are respectively gap-mounted on the outer peripheral sides of the two cameras and one end thereof is respectively fixed on the end faces of the two fixing seats that are close to each other; one side surface of the two lenses is respectively sealed on the other end of the two fixing tubes; one side surface of the two elastic members is respectively fixed on the other side surface of the two lenses.

[0006] The beneficial effect of the present invention is that the two connecting seats of the end effector are used to drive the two fixing seats to move closer to or away from each other. Since the other ends of the two fixing tubes fixed on the two fixing seats are close to each other and are fixed with lenses and elastic parts, the elastic parts can be used to flexibly clamp strawberries to avoid damage to the strawberries.

[0007] Based on the above technical solution, the present invention can also be improved as follows.

[0008] Furthermore, the two visual-tactile sensing clamps also include a light source board, lamp beads and a light distributing sheet. There are multiple light source boards and they are distributed on the outer peripheral side of the camera at intervals along the circumference of the fixed tube. The plate surfaces of the multiple light source boards are arranged at an angle α with the mirror surface of the lens and are all fixed in the fixed tube; there are multiple lamp beads and they are respectively fixed on the multiple light source boards; there are multiple light distributing sheets and one side of the light source sheets is attached to the side of the multiple light source boards corresponding to the lamp beads installed.

[0009] A further beneficial effect of the above method is that by using multiple light-homogenizing sheets distributed on one side of the corresponding lamp beads of multiple light source panels, multiple independent point light sources can be converted into approximate surface light sources, providing a good field of view for camera observation.

[0010] Furthermore, the angle α is 100-120°.

[0011] Furthermore, the lamp beads on the light source panels have different colors.

[0012] A further beneficial effect of the above method is that the multiple lamp beads on the multiple light source panels can be red, yellow, blue and other colors respectively, thereby providing a multi-color evenly distributed light source in the fixed tube.

[0013] Furthermore, the elastic member includes a silicone layer, a black mark dot matrix layer, a photosensitive layer and a contact layer which are connected in sequence from a direction away from the lens to a direction close to the lens.

[0014] The above further beneficial effects are: the elastic member is divided into four layers, the first layer from the direction away from the lens to the direction close to the lens is mainly made of food-grade liquid transparent silicone (Shore hardness is 5 after curing), the second layer is a 10×10 black marking dot matrix, which is obtained by pressing and marking with a dot matrix needle attached to the black silicone, the third layer is a photosensitive layer of spherical aluminum metal powder (with a diameter of about 1-3μm) to better receive the corresponding light signal when the elastomer is deformed, and the fourth layer, which is the contact layer with the object, is an extremely thin layer of silicone, so as not to lose the deformation accuracy of the photosensitive layer while protecting the photosensitive layer; the overall thickness is mainly the first layer of transparent silicone to provide deformation depth, thereby ensuring the high resolution of subsequent image processing of the sensor; this clamping finger designed based on visual tactile sensing technology can extract contact information such as contact area and normal force distribution estimation when clamping strawberries, thereby achieving stable clamping of strawberries.

[0015] Furthermore, the end effector includes a base, a servo, a gear, two racks and two connecting seats, the top of the base is provided with a fixed groove and two slide grooves, the two slide grooves are distributed on both sides of the fixed groove and are both connected with the fixed groove; the servo is fixed to the bottom of the fixed groove and its output shaft is arranged along the height direction of the base; the gear sleeve is fixed on the output shaft of the servo; the two racks slide in the two slide grooves respectively and are meshed with the gears so as to approach or move away from each other under the drive of the gears; the two connecting seats are respectively fixed on the two racks.

[0016] In addition, a strawberry contact information sensing method is provided, comprising the strawberry flexible clamping device, and the specific steps are as follows:

[0017] S1, holding the strawberry stem to adjust the position of the strawberry fruit so that the strawberry fruit is between the two elastic members;

[0018] S2, adjusting the distance between the two connecting seats in the end effector, and controlling the travel of the two elastic members to clamp the strawberry;

[0019] S3. During the clamping process, the continuous deformation images of the elastic member are obtained through the camera inside the visual-tactile sensing gripper, and the contact area and the contact normal force of the visual-tactile sensing gripper and the strawberry are displayed through the information perception model for the series of images;

[0020] S4, inputting the real-time contact normal force on the strawberry into the feedback algorithm, and adjusting the stroke of the visual-tactile sensor gripper according to the empirical threshold of the strawberry force obtained from the experiment;

[0021] S5. When the visual-tactile sensor gripper is in a stable state, release the strawberry stems. After releasing the gripper, the strawberries in the visual-tactile sensor gripper are in a stable state, and when the visual-tactile sensor gripper is released, there is no obvious damage to the strawberries, and the purpose is achieved.

[0022] Furthermore, between S3 and S2, the camera is manually focused so that it can obtain a clear image; the brightness of multiple light source panels is adjusted by changing the light source voltage to allow the internal cavity to obtain appropriate light. Too high brightness will make it difficult for the camera to capture changes in pixel values ​​of the image, and too low brightness will cause the camera to capture images with too much noise due to insufficient light.

[0023] Furthermore, the information perception model uses the AFE-Unet3+ neural network model, and the training process is as follows:

[0024] S1. Connect the visual-tactile sensor gripper to the indenter of a press (ZQ-990B multifunctional electric tensile testing machine: maximum measuring force 100N; force resolution 0.001N; displacement resolution 0.01mm), place an acrylic experimental mold on the table, and then control the indenter to move downward. Use the camera inside the visual-tactile sensor gripper to obtain contact images of the elastic part when it contacts different molds and the indenter applies different forces;

[0025] S2. After acquiring the original contact image, use the script to collect the contact area labels;

[0026] S3. After obtaining the binary contact label, the true value of the normal force is obtained by reading the force reading of the press at the contact moment. Since the sensor and the mold are in parallel contact in the experiment, to obtain the pixel-level force distribution label, it is only necessary to divide the true force value by the number of non-zero pixels of the contact label by formula (1) to obtain the unit force value. Then, this value is assigned to each non-zero pixel by formula (2) to obtain a complete pixel-level force distribution label.

[0027]

[0028] S4. The contact images, pixel-level force distribution labels and normal force true values ​​collected at the same time are taken as a set of data, and the AFE-Unet3+ neural network model is used to train the collected multiple data sets to generate an information perception model.

[0029] Furthermore, the strawberry stress threshold test includes the following specific operations:

[0030] S1. First, replace the elastic part of the visual tactile sensor gripper with an auxiliary finger attached with the same silicone elastic part, and connect the auxiliary finger to the pressure head of a dynamometer (range 2N; graduation value 0.001; accuracy ±1%);

[0031] S2, then holding the strawberry stem, placing the strawberry fruit between the two elastic members, controlling one elastic member in the visual-tactile sensor clamp to slowly apply pressure to the strawberry, observing the dynamometer reading, and after reaching a certain value, maintaining this state, loosening the fruit pedicle, reading the dynamometer reading, and placing the strawberry in an unsupported suspended state;

[0032] S3. By applying different forces to the strawberry, the damage of the strawberry under different force ranges is obtained, and the force range in which the strawberry can be in a stable unsupported suspended state without any damage is determined, that is, the strawberry force empirical threshold test is completed. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the three-dimensional structure of a flexible strawberry clamping device of the present invention;

[0034] Figure 2 This is a schematic diagram of the internal structure of a flexible strawberry clamping device of the present invention;

[0035] Figure 3 It is a schematic diagram of the assembly structure of the visual-tactile sensing gripper in a strawberry flexible gripping device of the present invention;

[0036] Figure 4 It is a schematic diagram of the disassembled structure of the visual-tactile sensing gripper in a strawberry flexible gripping device of the present invention;

[0037] Figure 5 It is a three-dimensional structural diagram of a strawberry force experience threshold test platform in a strawberry contact information perception method of the present invention;

[0038] Figure 6 It is a schematic diagram of the process of obtaining the information perception model in the strawberry contact information perception method of the present invention;

[0039] Figure 7 This is a flow chart of the strawberry force empirical threshold test in the strawberry contact information perception method of the present invention

[0040] Figure 8 The present invention is a flow chart of a flexible strawberry clamping device.

[0041] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0042] 1. End effector, 11. Connecting seat, 12. Base, 121. Slide, 13. Servo, 14. Gear, 15. Rack, 2. Visual and tactile sensor gripper, 21. Fixed seat, 22. Camera, 23. Fixed cylinder, 24. Lens, 25. Elastic part, 26. Light source board, 27. Lamp beads, 28. Light equalizer, 3. Press. DETAILED DESCRIPTION

[0043] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0044] like Figure 1 and Figure 4As shown, a flexible strawberry clamping device comprises: an end effector 1 and a visual-tactile sensing gripper 2, wherein the end effector 1 is provided with two connecting seats 11 which can be close to or away from each other; the visual-tactile sensing grippers 2 are two relatively arranged and each comprises a fixing seat 21, a camera 22, a fixing tube 23, a lens 24 and an elastic member 25, the two fixing seats 21 are respectively fixed on the two connecting seats 11; the two cameras 22 are respectively fixed on the end surfaces of the two fixing seats 21 which are close to each other; the two fixing tubes 23 are respectively sleeved on the outer peripheral sides of the two cameras 22 and one end thereof is respectively fixed on the end surfaces of the two fixing seats 21 which are close to each other; one side surface of the two lenses 24 is respectively sealed on the other end of the two fixing tubes 23; one side surface of the two elastic members 25 is respectively fixed on the other side surface of the two lenses 24.

[0045] like Figure 1 and Figure 4 As shown, in some specific embodiments, the two visual-tactile sensing grippers 2 may also include a light source board 26, lamp beads 27 and a light-distributing sheet 28. There are multiple light source boards 26 and they are distributed on the outer peripheral side of the camera 22 along the circumferential direction of the fixed tube 23. The plate surfaces of the multiple light source boards 26 are arranged at an angle α with the mirror surface of the lens 24 and are all fixed in the fixed tube 23; there are multiple lamp beads 27 and they are respectively fixed on the multiple light source boards 26; there are multiple light-distributing sheets 28 and one side of the light source boards 28 is attached to the side of the multiple light source boards 26 corresponding to the lamp beads 27 installed.

[0046] Specifically, the angle α may be 100-120°.

[0047] Specifically, the multiple lamp beads 27 on the multiple light source panels 26 have different colors.

[0048] In some specific embodiments, the elastic member 25 may include a silicone layer, a black mark dot matrix layer, a photosensitive layer, and a contact layer connected in sequence from a direction away from the lens 24 to a direction close to the lens 24 .

[0049] like Figure 1 and Figure 2 In some specific embodiments, the end effector 1 includes a base 12, a servo 13, a gear 14, two racks 15 and two connecting seats 11. The top of the base 12 is provided with a fixed groove and two slide grooves 121. The two slide grooves 121 are distributed on both sides of the fixed groove and are both connected with the fixed groove; the servo 13 is fixed to the bottom of the fixed groove and its output shaft is arranged along the height direction of the base 12; the gear 14 is sleeved on the output shaft of the servo 13; the two racks 15 slide in the two slide grooves 121 respectively and are meshed and connected with the gear 14 so that they are close to or away from each other under the drive of the gear 14; the two connecting seats 11 are respectively fixed on the two racks 15.

[0050] In addition, a strawberry contact information sensing method is provided, including a strawberry flexible clamping device, and the specific steps are as follows:

[0051] S1, holding the strawberry stem to adjust the position of the strawberry fruit so that the strawberry fruit is between the two elastic members 25;

[0052] S2, adjusting the distance between the two connecting seats 11 in the end effector 1, and controlling the travel of the two elastic members 25 to clamp the strawberries;

[0053] S3, during the clamping process, the camera 22 inside the visual-tactile sensing gripper 2 obtains continuous deformation images of the elastic member 25, and at the same time, for the series of images, the contact area between the visual-tactile sensing gripper 2 and the strawberry and the contact normal force are displayed through the information perception model;

[0054] S4, inputting the real-time contact normal force on the strawberry into the feedback algorithm, and adjusting the stroke of the visual-tactile sensing gripper 2 according to the empirical threshold of the strawberry force obtained from the experiment;

[0055] S5. When the visual-tactile sensor gripper 2 is in a stable state, release the strawberry stems. After releasing the strawberries in the visual-tactile sensor gripper 2, the strawberries are in a stable state, and when the visual-tactile sensor gripper 2 is released, there is no obvious damage to the strawberries, and the purpose is achieved.

[0056] In some specific embodiments, between S3 and S2, the camera is manually focused so that a clear image can be obtained.

[0057] In some specific embodiments, the information perception model adopts the AFE-Unet3+ neural network model, and the training process is as follows:

[0058] S1, connect the visual-tactile sensing gripper 2 to the pressure head of the press machine 3, and place an acrylic experimental mold on the table, then control the pressure head to move downward, and obtain contact images of the elastic member 25 when it contacts different molds and the pressure head applies different forces through the internal camera 22 of the visual-tactile sensing gripper 2;

[0059] S2. After acquiring the original contact image, use the script to collect the contact area labels;

[0060] S3. After obtaining the binary contact label, the true value of the normal force is obtained by reading the force reading of the press 3 at the contact moment. Since the sensor and the mold are in parallel contact in the experiment, to obtain the pixel-level force distribution label, it is only necessary to divide the true value of the force by the number of non-zero pixels of the contact label by formula 1 to obtain the unit force value. Then, by assigning this value to each non-zero pixel as in formula 2, a complete pixel-level force distribution label can be obtained.

[0061]

[0062] S4. The contact images, pixel-level force distribution labels and normal force true values ​​collected at the same time are taken as a set of data, and the AFE-Unet3+ neural network model is used to train the collected multiple data sets to generate an information perception model.

[0063] In some specific embodiments, the strawberry stress empirical threshold test includes:

[0064] S1. First, the elastic member 25 of the visual-tactile sensor gripper 2 is replaced with an auxiliary finger attached with the same silicone elastic member 25, and the auxiliary finger is connected to the dynamometer pressure head;

[0065] S2, then hold the strawberry stem, place the strawberry fruit between the two elastic members 25, control one elastic member 25 in the visual-tactile sensor gripper 2 to slowly apply pressure to the strawberry, observe the dynamometer reading, and when a certain value is reached, maintain this state, release the fruit stem, read the dynamometer reading, and put the strawberry in an unsupported suspended state;

[0066] S3. By applying different forces to the strawberry, the damage of the strawberry under different force ranges is obtained, and the force range in which the strawberry can be in a stable unsupported suspended state without any damage is determined, that is, the strawberry force empirical threshold test is completed.

[0067] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A flexible strawberry clamping device, characterized in that: include: An end effector (1), wherein the end effector (1) has two connection seats (11) that can move closer to each other or farther away from each other; A visual-tactile sensor gripper (2), wherein the visual-tactile sensor gripper (2) is composed of two relatively arranged grippers, each comprising a fixing seat (21), a camera (22), a fixing tube (23), a lens (24) and an elastic member (25), wherein the two fixing seats (21) are respectively fixed on the two connecting seats (11); the two cameras (22) are respectively fixed on the end surfaces of the two fixing seats (21) close to each other; the two fixing tubes (23) are respectively sleeved on the outer peripheral sides of the two cameras (22) and one end thereof is respectively fixed on the end surfaces of the two fixing seats (21) close to each other; one side of the two lenses (24) is respectively sealed on the other end of the two fixing tubes (23); and one side of the two elastic members (25) is respectively fixed on the other side of the two lenses (24).

2. A strawberry flexible clamping device according to claim 1, characterized in that: The two visual-tactile sensing grippers (2) also each comprise a light source board (26), a lamp bead (27) and a light-distributing sheet (28); the light source boards (26) are multiple and are distributed at intervals along the circumference of the fixed tube (23) on the outer peripheral side of the camera (22); the plate surfaces of the multiple light source boards (26) are arranged at an angle α with the mirror surface of the lens (24) and are all fixed in the fixed tube (23); the lamp bead (27) is multiple and is respectively fixed on the multiple light source boards (26); the light-distributing sheet (28) is multiple and one side thereof is attached to a side of the multiple light source boards (26) corresponding to the side on which the lamp bead (27) is installed.

3. A strawberry flexible clamping device according to claim 2, characterized in that: The angle α is 100-120°.

4. A strawberry flexible clamping device according to claim 2, characterized in that: The multiple lamp beads (27) on the multiple light source panels (26) have different colors.

5. A strawberry flexible clamping device according to claim 1, characterized in that: The elastic member (25) comprises a silicone layer, a black mark dot matrix layer, a photosensitive layer and a contact layer which are connected in sequence from a direction away from the lens (24) to a direction close to the lens (24).

6. A strawberry flexible clamping device according to claim 1, characterized in that: The end effector (1) comprises a base (12), a steering gear (13), a gear (14), two racks (15) and two connecting seats (11); a fixed groove and two slide grooves (121) are provided at the top of the base (12); the two slide grooves (121) are distributed on both sides of the fixed groove and are both connected with the fixed groove; the steering gear (13) is fixed to the bottom of the fixed groove and its output shaft is arranged along the height direction of the base (12); the gear (14) is sleeved on the output shaft of the steering gear (13); the two racks (15) slide in the two slide grooves (121) respectively and are meshed and connected with the gear (14) so ​​as to approach or move away from each other under the drive of the gear (14); the two connecting seats (11) are respectively fixed on the two racks (15).

7. A strawberry contact information perception method, characterized in that: The strawberry flexible clamping device comprising any one of claims 1 to 6, wherein the specific steps are as follows: S1, holding the strawberry stem to adjust the position of the strawberry fruit so that the strawberry fruit is between the two elastic members (25); S2, adjusting the distance between the two connecting seats (11) in the end effector (1) and controlling the travel of the two elastic members (25) to clamp the strawberries; S3, during the clamping process, the continuous deformation images of the elastic member (25) are obtained by the internal camera (22) of the visual-tactile sensing gripper (2), and the contact area and the contact normal force of the visual-tactile sensing gripper (2) and the strawberry are displayed based on the series of images by using an information perception model; S4, inputting the normal contact force received by the strawberry in real time into the feedback algorithm, and adjusting the travel of the visual-tactile sensing gripper (2) according to the empirical threshold of the strawberry force received in the experiment; S5. When the visual-tactile sensor gripper (2) is in a stable state, the strawberry stems are released. After the gripper is released, the strawberries in the visual-tactile sensor gripper (2) are in a stable state. When the visual-tactile sensor gripper (2) is released, the strawberries have no obvious damage, and the purpose is achieved.

8. A strawberry contact information sensing method according to claim 7, characterized in that: Between S3 and S2, the camera was manually focused to enable it to obtain a clear image.

9. A strawberry contact information sensing method according to claim 7, characterized in that: The information perception model uses the AFE-Unet3+ neural network model, and the training process is as follows: S1, connecting the visual-tactile sensing gripper (2) to the pressure head of the press machine (3), placing an acrylic experimental mold on the table, and then controlling the pressure head to move downward, and obtaining contact images of the elastic member (25) when contacting different molds and applying different forces to the pressure head through the internal camera (22) of the visual-tactile sensing gripper (2); S2. After acquiring the original contact image, use the script to collect the contact area labels; S3. After obtaining the binary contact label, the true value of the normal force is obtained by reading the force reading of the press (3) at the contact moment. Since the sensor and the mold are in parallel contact in the experiment, to obtain the pixel-level force distribution label, it is only necessary to divide the true value of the force by the number of non-zero pixels of the contact label by formula (1) to obtain the unit force value. Then, by assigning this value to each non-zero pixel as in formula (2), a complete pixel-level force distribution label can be obtained. S4. The contact images, pixel-level force distribution labels and normal force true values ​​collected at the same time are taken as a set of data, and the AFE-Unet3+ neural network model is used to train the collected multiple data sets to generate an information perception model.

10. A strawberry contact information sensing method according to claim 7, characterized in that: The strawberry stress empirical threshold test includes: S1. First, the elastic member (25) of the visual-tactile sensor gripper (2) is replaced with an auxiliary finger attached with the same silicone elastic member (25), and the auxiliary finger is connected to the pressure head of the dynamometer; S2, then holding the strawberry stem, placing the strawberry fruit between the two elastic members (25), controlling one of the elastic members (25) in the visual-tactile sensing gripper (2) to slowly apply pressure to the strawberry, observing the reading of the dynamometer, and when a certain value is reached, maintaining this state, releasing the fruit stem, and reading the reading of the dynamometer, so that the strawberry is in an unsupported suspended state; S3. By applying different forces to the strawberry, the damage of the strawberry under different force ranges is obtained, and the force range in which the strawberry can be in a stable unsupported suspended state without any damage is determined, that is, the strawberry force empirical threshold test is completed.

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