Closed angle measurement experiment table for non-destructive grasping of fruits and vegetables with handles by flexible clamping jaws
By designing a flexible gripper non-destructive gripping experimental platform, and using plug-in locking components and thin-film pressure sensors, the platform achieves precise positioning of the force points on fruits and vegetables and accurate calibration of the closing angle. This solves the problems of high damage rate and large positioning error of flexible grippers in fruit and vegetable harvesting, reduces debugging costs, and adapts to the harvesting needs of multiple varieties.
Patent Information
- Application Number
- CN202521155379.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-06
- Publication Date
- 2026-02-24
- Estimated Expiration
- 2035-06-06
AI Technical Summary
Existing technologies lack dedicated experimental equipment for precisely calibrating the closing angle of flexible grippers, resulting in high fruit and vegetable damage rates, insufficient positioning accuracy, and increased debugging costs due to the lack of a sensor feedback mechanism, making it unable to meet the needs of multi-variety harvesting.
A flexible gripper non-destructive grasping experimental platform was designed, comprising a frame assembly, a positioning assembly, a clamping assembly, a rotating assembly, a sensing assembly, and a control module. It achieves ±0.1mm precision positioning through plug-and-play locking components, and combines a thin-film pressure sensor and a mechanical relay to achieve accurate calibration of the closing angle and real-time force feedback.
It achieves ±0.1mm precision positioning of the force points of fruits and vegetables, reduces the damage rate of fruits and vegetables, reduces debugging costs, adapts to the needs of multi-variety harvesting, and improves the non-destructive gripping efficiency of flexible grippers.
Smart Images
Figure CN223940520U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of agricultural machinery testing equipment technology, and in particular to a special experimental platform for measuring the optimal closing angle when a flexible gripper non-destructively grasps fruits and vegetables with a diameter. Background Technology
[0002] Flexible grippers are widely used in fruit and vegetable harvesting due to their adaptive properties, but the maximum gripping force that different fruits and vegetables can withstand varies significantly.
[0003] Flexible grippers face the following key bottlenecks in industrial applications:
[0004] 1. Incomplete parameter calibration leads to a high damage rate.
[0005] The mechanical properties of different fruits and vegetables vary significantly (e.g., the damage threshold for strawberries is ≤5N, while that for apples can reach 30N), but current technology lacks dedicated experimental equipment to accurately calibrate the closing angle of flexible grippers. Users can only set the closing angle parameters based on experience; an excessively large closing angle can easily cause bruising to fruits and vegetables, while an excessively small angle leads to unstable gripping. Currently available flexible gripper testing equipment cannot accurately locate the force points on fruits and vegetables, nor does it integrate a real-time force feedback mechanism, resulting in a high damage rate, especially in the early stages. Only after repeated adjustments by the user can a suitable parameter be set, but this parameter is also set based on experience, and the most suitable angle parameter cannot be accurately found. These limitations restrict the application of flexible grippers in the field of non-destructive harvesting.
[0006] 2. Insufficient positioning accuracy amplifies measurement errors.
[0007] The gripping force distribution of the flexible gripper is highly position-dependent (the strongest force point in this invention is located at the fifth crossbeam of the flexible gripper). General-purpose clamps cannot achieve precise positioning of the force point, and existing solutions (such as three-jaw chucks) have a positioning error >5mm, causing calibration data to become invalid.
[0008] 3. The lack of a sensor feedback mechanism increases debugging costs.
[0009] Current force control systems for harvesting robots, which can adjust the gripping force in real time, are expensive and have a response delay of >0.5 seconds. Small and medium-sized farmers cannot afford them and are forced to use fixed-angle modes, which cannot adapt to the harvesting needs of multiple varieties. Utility Model Content
[0010] The purpose of this invention is to solve the problem in the prior art that flexible grippers cannot calibrate the non-destructive closing angle when grasping different fruits and vegetables, especially addressing the defects of inaccurate fruit and vegetable positioning and lack of gripping force monitoring.
[0011] To achieve the above objectives, the flexible gripper non-destructive gripping and closing angle measurement experimental platform for fruits and vegetables with handles of this utility model includes:
[0012] Frame components, positioning components, clamping components, rotating components, sensing components, and control modules;
[0013] The frame assembly includes a support frame made of aluminum profiles connected together, with a perforated aluminum profile horizontally connected to the top of the support frame. The two are fixedly connected to form a support structure; the horizontal perforated aluminum profile has a sliding hole that is open at both the top and bottom.
[0014] The positioning assembly includes a tension plate that slides through a sliding hole, a locking bracket fixed to perforated aluminum profiles on both sides of the sliding hole, and a plug-in locking component that passes through the locking bracket and the tension plate.
[0015] The clamping assembly includes a cable tie bracket fixed to the tension plate and an adjustable cable tie; the adjustable cable tie is used to tie the stems of the experimental fruits and vegetables to the cable tie bracket.
[0016] The rotating assembly includes a gripper base with a boss hole and a flexible gripper with a boss at the bottom. The two form a rotating pair by the cooperation of the boss and the boss hole.
[0017] The sensing component includes a thin-film pressure sensor attached to the center of the flexible gripper.
[0018] The control module is electrically connected to the driving mechanism of the thin-film pressure sensor and the flexible gripper. When the force value detected by the thin-film pressure sensor reaches the preset fruit and vegetable damage threshold, the control module triggers the flexible gripper to stop moving.
[0019] The flexible gripper has horizontal beams spaced at intervals, which serve as the skeleton of the flexible gripper. The fifth horizontal beam from the bottom is the gripping center of the flexible gripper.
[0020] The insertion and removal locking component is a columnar structure, and the insertion and removal locking component is clearance-fitted with the through hole of the locking bracket and the tension plate with a clearance ≤ 0.1mm.
[0021] The clearance between the boss and the boss hole of the rotating pair is ≤0.5mm.
[0022] The sliding holes of the horizontal perforated aluminum profile are long, narrow through holes that vertically penetrate the horizontal perforated aluminum profile, providing the stretching plate with a sliding stroke of more than 6 centimeters up and down.
[0023] The control module is connected to a mechanical relay. When the output signal of the membrane pressure sensor reaches the threshold voltage, the relay cuts off the power supply to the flexible gripper.
[0024] The locking bracket is fixed to the perforated aluminum profile by threaded fasteners, with its edge 3mm away from the edge of the sliding hole.
[0025] This utility model has the following advantages:
[0026] This invention achieves ±0.1mm precision positioning of the force-bearing point of fruits and vegetables through the plug-in locking mechanism of the positioning component, solving the problem of large positioning errors in existing clamps. Combined with a thin-film pressure sensor and a threshold triggering mechanism, it facilitates accurate calibration of the closing angle through experiments. The thin-film pressure sensor is attached to the center of the flexible gripper, directly capturing the maximum gripping force and avoiding errors in force calculation algorithms.
[0027] The crossbeam serves a dual purpose: force transmission and sensor positioning. When gripping fruits and vegetables, the crossbeam undergoes elastic bending deformation, converting the closing motion of the grippers into a wrapping force on the produce. The deformation of the crossbeam directly determines the magnitude of the gripping force (the larger the bending angle, the greater the applied force). The fifth crossbeam from the bottom is the gripping center of the flexible grippers, making it very convenient and accurate to position the film pressure sensor when attaching it.
[0028] The clearance between the insertion locking component and the through hole of the locking bracket and tension plate is ≤0.1mm, which can eliminate the cumulative positioning error caused by mechanical clearance and ensure the alignment accuracy of the maximum force point (clamping center). The clearance of the rotating pair is ≤0.5mm, which can limit the swing amplitude of the gripper and ensure that the gripping point is always in contact with the maximum outer diameter of the fruit and vegetable.
[0029] The vertical sliding stroke of the stretching plate exceeds 6 cm, covering the experimental needs of common fruit and vegetable sizes, facilitating experiments on various common fruits and vegetables. The mechanical relay offers rapid response and low cost, making it suitable for controlling clamping force. The locking bracket is 3 mm from the edge of the sliding hole to prevent it from obstructing the sliding path and ensure interference-free movement of the stretching plate. Attached Figure Description
[0030] Figure 1 This is a three-dimensional structural diagram of the present invention, showing the overall structure of the present invention.
[0031] Figure 2 yes Figure 1 The enlarged view at point A shows the core structure of the positioning component.
[0032] Figure 3 This is a schematic diagram of the structure of this utility model.
[0033] Figure 4 yes Figure 3 Top view.
[0034] Figure 5 yes Figure 3 A bottom view.
[0035] Figure 6 yes Figure 1 The enlarged view at point B shows the core structure of the clamping component. Detailed Implementation
[0036] like Figures 1 to 6 As shown, this utility model discloses a flexible gripper non-destructive gripping and measuring test platform for the closing angle of fruits and vegetables with handles, including a frame assembly, a positioning assembly, a clamping assembly, a rotating assembly, a sensing assembly, and a control module.
[0037] The frame assembly includes a support frame 1 made of aluminum profiles, with a horizontally perforated aluminum profile 2 connected to the top of the support frame 1. The two are fixedly connected to form a support structure. The horizontally perforated aluminum profile 2 has through holes at both ends. Figure 2 In the figure, the intersection of the sliding hole and the tension plate 3 is the location of the sliding hole. To avoid clutter, the sliding hole is not indicated in the figure.
[0038] The positioning assembly includes a tension plate 3 that slides through a sliding hole, a locking bracket 4 fixed to perforated aluminum profiles 2 on both sides of the sliding hole, and a plug-in locking member 5 that passes through the locking bracket 4 and the tension plate 3. The tension plate 3 is provided with multiple locking holes 6 at even intervals on its upper and lower sides for the plug-in locking member 5 to pass through. By plugging and unplugging the locking member 5 through different locking holes 6, different fruit and vegetable positioning heights can be accommodated.
[0039] The clamping assembly includes a cable tie bracket 6 fixed to the lower end of the tension plate 3 and an adjustable cable tie 7; the adjustable cable tie 7 is used to tie and fix the fruit stem 8 of the experimental fruits and vegetables 9 to the cable tie bracket 6.
[0040] The rotating assembly includes a gripper base 10 with a boss hole 11 and a flexible gripper 13 with a boss 12 on the bottom. The two form a rotating pair by the cooperation of the boss 12 and the boss hole 11.
[0041] The sensing component includes a thin-film pressure sensor 14 attached to the center of the flexible gripper 13;
[0042] The control module is electrically connected to the driving mechanism of the thin-film pressure sensor 14 and the flexible gripper 13. When the force value detected by the thin-film pressure sensor 14 reaches the preset damage threshold for fruits and vegetables 9, the control module triggers the flexible gripper 13 to stop moving and records the rotation angle. The control module is an integrated circuit or a microcontroller.
[0043] This invention achieves ±0.1mm precision positioning of the force-bearing point of fruits and vegetables 9 through the plug-in locking component 5 of the positioning assembly, solving the problem of large positioning errors in existing clamps. Combined with the thin-film pressure sensor 14 and the threshold triggering mechanism, it is easy to achieve accurate calibration of the closing angle through experiments. The thin-film pressure sensor 14 is attached to the center of the flexible gripper 13 to directly capture the maximum gripping force, avoiding errors in the force value calculation algorithm.
[0044] The flexible gripper 13 has horizontal beams 15 spaced apart vertically. The horizontal beams 15 serve as the skeleton of the flexible gripper 13. The fifth horizontal beam 15 from bottom to top is the gripping center of the flexible gripper 13 (i.e., the bonding part of the thin film pressure sensor 14).
[0045] The crossbeam 15 serves a dual function of force transmission and sensor positioning. When gripping fruits and vegetables 9, the crossbeam 15 undergoes elastic bending deformation, converting the closing motion of the grippers into a wrapping force on the fruits and vegetables 9; the deformation of the crossbeam 15 directly determines the magnitude of the gripping force (the larger the bending angle, the greater the applied force). The fifth crossbeam 15 from the bottom up is the gripping center of the flexible gripper 13, which is very convenient and accurate for positioning when attaching the thin-film pressure sensor 14.
[0046] The insertion and removal locking component 5 is a columnar structure. The insertion and removal locking component 5 is fitted with the through hole of the locking bracket 4 and the tension plate 3 with a clearance of ≤0.1mm. This can eliminate the cumulative positioning error caused by mechanical clearance and ensure the alignment accuracy of the maximum force point (clamping center).
[0047] The clearance between the boss 12 and the boss hole 11 of the rotating pair is ≤0.5mm, which can limit the swing amplitude of the gripper and ensure that the gripping point is always in contact with the maximum outer diameter of the fruit and vegetable 9.
[0048] The sliding hole of the horizontal perforated aluminum profile 2 is an elongated through hole that vertically penetrates the horizontal perforated aluminum profile 2, providing a vertical sliding stroke of more than 6 cm for the stretching plate 3. The vertical sliding stroke of the stretching plate 3 is more than 6 cm, which can cover the experimental needs of common fruits and vegetables 9 and facilitate experiments on various common fruits and vegetables 9.
[0049] The control module is connected to a mechanical relay. When the output signal of the thin-film pressure sensor 14 reaches the threshold voltage, the relay cuts off the driving power to the flexible gripper 13. Both the control module and the mechanical relay are conventional technologies and are not shown in the figure. The mechanical relay has a fast response, low cost, and is suitable for controlling the clamping force.
[0050] The locking bracket 4 is fixed to the perforated aluminum profile 2 by threaded fasteners, with its edge 3mm from the edge of the sliding hole. The locking bracket 4 is 3mm from the edge of the sliding hole to prevent the bracket from obstructing the sliding path and to ensure that the tension plate 3 moves without interference.
[0051] The working process of this utility model is as follows:
[0052] I. Experimental Preparation Stage
[0053] 1. Frame assembly:
[0054] Four vertical aluminum profiles are embedded into the grooves of the gripper base 10 and fixed, and the top is connected to the horizontal aluminum profile to form a support frame 1; the perforated aluminum profile 2 is fixed to the middle of the horizontal aluminum profile by bolts.
[0055] 2. Installation of positioning components:
[0056] The locking bracket 4 is threaded onto the perforated aluminum profile 2, with the edge 3mm from the hole; the stretching plate 3 is inserted into the sliding hole of the perforated aluminum profile 2.
[0057] II. Fruits and Vegetables (9 fixed items):
[0058] 1. Fixing fruits and vegetables 9: Insert the stem 8 of the fruit and vegetable to be tested 9 into the adjustable cable tie 7, and tighten the cable tie to fix it to the lower end of the cable tie bracket 6;
[0059] 2. Height adjustment: Slide the stretching plate 3 up and down along the vertical sliding hole of the horizontal perforated aluminum profile 2 so that the gripping point of the fruit and vegetable 9 is aligned with the clamping center of the flexible gripper 13 (i.e., the fifth crossbeam 15).
[0060] 3. Position locking: Insert the locking piece 5 through the corresponding holes of the locking bracket 4 and the tension plate 3 to fix the position of the fruit and vegetable 9 with an accuracy of ±0.1mm (gap ≤0.1mm).
[0061] III. Gripper Posture Adjustment
[0062] Based on the surface shape of the fruit and vegetable 9 (e.g., non-spherical fruit and vegetable 9), rotate the flexible gripper 13 so that its gripping surface fits the point with the largest outer diameter of the fruit and vegetable 9 (the gap between the rotating parts is ≤0.5mm to ensure that the swing amplitude is controllable).
[0063] IV. Closure Angle Calibration
[0064] The flexible gripper 13 drive mechanism is activated, and the flexible gripper 13 closes towards the fruit and vegetable 9;
[0065] The thin-film pressure sensor 14 monitors the gripping force value in real time and transmits the data to the control module (integrated circuit / microcontroller); when the gripping force reaches the preset fruit and vegetable damage threshold (such as 5N for strawberries and 25N for apples), the control module triggers a mechanical relay to instantly cut off the drive power, and the gripper stops moving.
[0066] Record the rotation angle of the flexible gripper 13 at this time, and define it as the non-destructive gripping closing angle of the fruit and vegetable 9, thus completing the calibration of the non-destructive gripping closing angle of the fruit and vegetable 9.
[0067] By changing to different types of fruits and vegetables 9 and repeating steps two through four above, the calibration of the non-destructive grasping and closing angle of different types of fruits and vegetables 9 can be completed.
[0068] V. Data Application
[0069] The calibrated closing angle is input into the actual harvesting robot, and the flexible gripper 13 performs the gripping of the corresponding type of fruits and vegetables 9 at this angle, without the need for additional sensing devices.
[0070] The above embodiments are only used to illustrate and not limit the technical solutions of this utility model. Although the utility model has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the utility model without departing from the spirit and scope of the utility model. Any modifications or partial substitutions should be covered within the scope of the claims of this utility model.
Claims
1. A flexible gripper for non-destructive gripping of fruits and vegetables with handles, characterized in that... include: Frame components, positioning components, clamping components, rotating components, sensing components, and control modules; The frame assembly includes a support frame made of aluminum profiles connected together, with a perforated aluminum profile horizontally connected to the top of the support frame. The two are fixedly connected to form a support structure; the horizontal perforated aluminum profile has a sliding hole that is open at both the top and bottom. The positioning assembly includes a tension plate that slides through a sliding hole, a locking bracket fixed to perforated aluminum profiles on both sides of the sliding hole, and a plug-in locking component that passes through the locking bracket and the tension plate. The clamping assembly includes a cable tie bracket fixed to the tension plate and an adjustable cable tie; the adjustable cable tie is used to tie the stems of the experimental fruits and vegetables to the cable tie bracket. The rotating assembly includes a gripper base with a boss hole and a flexible gripper with a boss at the bottom. The two form a rotating pair by the cooperation of the boss and the boss hole. The sensing component includes a thin-film pressure sensor attached to the center of the flexible gripper. The control module is electrically connected to the driving mechanism of the thin-film pressure sensor and the flexible gripper. When the force value detected by the thin-film pressure sensor reaches the preset fruit and vegetable damage threshold, the control module triggers the flexible gripper to stop moving.
2. The flexible gripper non-destructive gripping and closing angle measurement experimental platform for fruits and vegetables with handles according to claim 1, characterized in that: The flexible gripper has horizontal beams spaced at intervals, which serve as the skeleton of the flexible gripper. The fifth horizontal beam from the bottom is the gripping center of the flexible gripper.
3. The flexible gripper non-destructive gripping and closing angle measurement experimental platform for fruits and vegetables with handles according to claim 1, characterized in that: The insertion and removal locking component is a columnar structure, and the insertion and removal locking component is clearance-fitted with the through hole of the locking bracket and the tension plate with a clearance ≤ 0.1mm.
4. The flexible gripper non-destructive gripping and closing angle measurement experimental platform for fruits and vegetables with handles according to claim 1, characterized in that: The clearance between the boss and the boss hole of the rotating pair is ≤0.5mm.
5. The flexible gripper non-destructive gripping and closing angle measurement experimental platform for fruits and vegetables with handles according to claim 1, characterized in that: The sliding holes of the horizontal perforated aluminum profile are long, narrow through holes that vertically penetrate the horizontal perforated aluminum profile, providing the stretching plate with a sliding stroke of more than 6 centimeters up and down.
6. The flexible gripper non-destructive gripping and closing angle measurement experimental platform for fruits and vegetables with handles according to claim 1, characterized in that: The control module is connected to a mechanical relay. When the output signal of the membrane pressure sensor reaches the threshold voltage, the relay cuts off the power supply to the flexible gripper.
7. The flexible gripper non-destructive gripping and closing angle measurement experimental platform for fruits and vegetables with handles according to claim 1, characterized in that: The locking bracket is fixed to the perforated aluminum profile by threaded fasteners, with its edge 3mm away from the edge of the sliding hole.