A self-cleaning end effector based on flexible joint force sensing

Abstract

This invention provides a self-cleaning end effector based on flexible joint force sensing, comprising a gripping device, a movable base, and a cutting and cleaning device. The gripping device includes a body and a flexible gripping structure. The body is equipped with the flexible gripping structure and is positioned above the movable base, allowing it to move on the base. The flexible gripping structure can deform to clamp the fruit stem. The cutting and cleaning device is positioned above the flexible gripping structure to cut the fruit stem clamped by the flexible gripping structure and clean the flexible gripping structure itself. This invention is compact and small, suitable for operation in confined spaces.

Description

Technical Field

[0001] This invention relates to the field of agricultural machinery technology, and in particular to a self-cleaning end effector based on flexible joint force sensing. Background Technology

[0002] Currently, existing end effectors, which are the devices that directly contact the fruit stems in harvesting robots, often suffer from problems such as excessively large claw tips or overall size, making it difficult to perform precise operations in confined spaces. Furthermore, existing harvesting end effectors have relatively limited functionality, lacking accurate force measurement capabilities and failing to provide timely and effective feedback on dangerous situations such as collisions with the surrounding environment during operation, thus increasing the risks involved in the operation.

[0003] Therefore, there is an urgent need for a self-cleaning end effector based on flexible joint force sensing. Summary of the Invention

[0004] This invention provides a self-cleaning end effector based on flexible joint force sensing, which solves the problem that current end effectors have large claw tip sizes and cannot provide accurate force measurement.

[0005] This invention provides a self-cleaning end effector based on flexible joint force sensing, including a clamping device, a movable base, and a cutting and cleaning device. The clamping device includes a body and a flexible clamping structure. The flexible clamping structure is provided on the body. The body is positioned above the movable base and can move on the movable base. The flexible clamping structure can deform to clamp the fruit stem. The cutting and cleaning device is positioned above the flexible clamping structure to cut the fruit stem clamped by the flexible clamping structure and clean the flexible clamping structure.

[0006] The self-cleaning end effector based on flexible joint force sensing, preferably, includes a flexible gripping structure comprising a left flexible joint, a right flexible joint, a left claw, a right claw, a left rubber-coated bearing, a right rubber-coated bearing, and a precision force measuring device. The tail end of the left flexible joint is connected to the main body, and the top end of the left flexible joint is connected to the left claw. The left rubber-coated bearing is mounted on the movable base and can fit against the outer side of the left flexible joint, which has an arc surface. The tail end of the right flexible joint is connected to the main body, and the top end of the right flexible joint is connected to the right claw. The right rubber-coated bearing is mounted on the movable base and can fit against the outer side of the right flexible joint, which also has an arc surface. The precision force measuring device is mounted on the main body. The left claw is connected to the precision force measuring device via the left flexible joint, and the right claw is connected to the precision force measuring device via the right flexible joint.

[0007] Preferably, the self-cleaning end effector based on flexible joint force sensing has slots on both the left and right flexible joints.

[0008] Preferably, the slot in the self-cleaning end effector based on flexible joint force sensing is I-shaped.

[0009] The self-cleaning end effector based on flexible joint force sensing, preferably, further includes fiber optic through-beam sensors, which are respectively disposed at the tips of the left and right claws.

[0010] The self-cleaning end effector based on flexible joint force sensing, preferably, includes a precision force measuring device comprising a first strain gauge, a second strain gauge, and a third strain gauge. The first strain gauge is disposed above the main body and along the moving direction of the clamping device. An opening groove is provided on the main body, and the second strain gauge is disposed in the opening groove. The third strain gauge is disposed on the side of the main body.

[0011] Preferably, the self-cleaning end effector based on flexible joint force sensing is further provided with multiple magnification structures on its body. The first strain gauge, the second strain gauge and the third strain gauge are respectively installed in front of the magnification structure, and the magnification structure is a hollow figure-eight shape.

[0012] The self-cleaning end effector based on flexible joint force sensing, preferably, includes a movable base comprising a sleeve, a bearing slide rail, a slider, and a bracket. The bearing slide rail is mounted on the sleeve, and the slider is mounted on the bearing slide rail. The slider is connected to the bottom of the main body via the bracket. The left-side rubber-coated bearing and the right-side rubber-coated bearing are respectively mounted on the sleeve, with the left-side rubber-coated bearing located on the left side of the bearing slide rail and the right-side rubber-coated bearing located on the right side of the bearing slide rail.

[0013] Preferably, in the self-cleaning end effector based on flexible joint force sensing, the sleeve is further provided with a groove, and the bearing slide rail and the slider are both disposed in the groove.

[0014] The self-cleaning end effector based on flexible joint force sensing, preferably, includes a cutting and cleaning device comprising a cover plate, a wedge block, a blade, and a high-pressure air pipe. The cover plate is disposed at the front of the sleeve, the wedge block is disposed on the cover plate, the blade is disposed on the wedge block, and the blade is located above the left and right claws. A circular hole is provided at the center of the cover plate, and the high-pressure air pipe is located in the circular hole. The extension direction of the pipe hole of the high-pressure air pipe is parallel to the inclined surface of the wedge block.

[0015] The beneficial effects are:

[0016] The front of the claw tip is equipped with a set of fiber optic sensors to detect whether the fruit stem has entered the gripping range of the claw tip.

[0017] The flexible joint adopts a parallel soft connection design, which has the advantages of being compact and easy to connect;

[0018] The curved surface on the outer side of the flexible joint forms a linear cam structure in conjunction with the rubber-coated bearing to ensure smooth movement;

[0019] The precision force measuring device is used to measure three-dimensional forces in the forward, lateral, and vertical directions. It is mainly achieved through three strain gauges and corresponding amplification structures to ensure accurate feedback of real-time changes in three-dimensional forces during operation. The precision force measuring device can also measure the weight of fruits and avoid collisions with surrounding obstacles, ensuring the accuracy and safety of the device during operation.

[0020] The air tube of the cutting and cleaning device delivers high-pressure gas to the tip of the claw to clean the fruit stem residue, ensuring the cleaning effect when the device is working continuously.

[0021] This invention has a compact and small structure, making it suitable for operation in confined spaces. Attached Figure Description

[0022] Figure 1 It is a schematic diagram of the structure of the present invention;

[0023] Figure 2 This is an exploded view of the structure of the present invention;

[0024] Figure 3 This is a top view of the gripping device;

[0025] Figure 4 This is a perspective view of the gripping device;

[0026] Figure 5 This is a schematic diagram of the cutting and cleaning device;

[0027] In the picture:

[0028] 1. Movable base; 1-1. Sleeve; 1-2. Load-bearing slide rail; 1-3. Slider; 1-4. Bracket; 1-5. Groove;

[0029] 2. Gripping device; 2-1. Left flexible joint; 2-2. Body; 2-3. Right flexible joint; 2-4. Left claw;

[0030] 2-5. Right claw; 2-6. Left rubber-coated bearing; 2-7. Right rubber-coated bearing; 2-8. Grooving;

[0031] 3-1, First strain gauge; 3-2, Second strain gauge; 3-3, Third strain gauge; 3-4, First magnified structure;

[0032] 3-5. Second enlarged structure; 3-6. Third enlarged structure;

[0033] 4. Cutting and removing device; 4-1. Cover plate; 4-2. Wedge block; 4-3. Blade; 4-4. High-pressure air pipe;

[0034] 5. Fiber optic through-beam sensor; 6. Opening slot. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0036] In the description of this invention, it should be noted that the terms "upper," "lower," etc., indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the system or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the use of terms such as "first," "second," and "third" to define components is merely for the convenience of distinguishing the aforementioned components; unless otherwise stated, these terms have no special meaning and should not be construed as indicating or implying relative importance.

[0037] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "setting," and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0038] This invention provides a self-cleaning end effector based on flexible joint force sensing, comprising a clamping device, a movable base, and a cutting and cleaning device. The clamping device includes a body and a flexible clamping structure. The flexible clamping structure is mounted on the body and is positioned above the movable base, allowing the body to move on the base. The flexible clamping structure is deformable to clamp fruit stems. The cutting and cleaning device is positioned above the flexible clamping structure to cut the fruit stems clamped by the flexible clamping structure and to clean the flexible clamping structure itself. This invention is compact and small, suitable for operation in confined spaces.

[0039] The following section uses a self-cleaning end effector based on flexible joint force sensing as an example to illustrate the entire technical process in detail.

[0040] Reference Figure 1 and Figure 2 As shown, a self-cleaning end effector based on flexible joint force sensing includes a clamping device 2, a movable base 1, and a cutting and cleaning device 4. The clamping device 2 includes a body 2-2 and a flexible clamping structure. The flexible clamping structure is provided on the body 2-2, and an optical fiber through-beam sensor 5 is provided at the end of the flexible clamping structure. The body 2-2 is positioned above the movable base 1 and can move on the movable base 1. The flexible clamping structure can deform to clamp the fruit stem. The cutting and cleaning device 4 is positioned above the flexible clamping structure to cut the fruit stem clamped by the flexible clamping structure and clean the flexible clamping structure.

[0041] Continue to refer to Figure 1 and Figure 2 As shown, the movable base 1 includes a sleeve 1-1, a bearing slide rail 1-2, a slider 1-3, and a bracket 1-4. The sleeve 1-1 is provided with the bearing slide rail 1-2, and the bearing slide rail 1-2 is provided with the slider 1-3. The slider 1-3 is connected to the bottom of the body 2-2 through the bracket 1-4. The left rubber-coated bearing 2-6 and the right rubber-coated bearing 2-7 are respectively provided on the sleeve 1-1. The left rubber-coated bearing 2-6 is located on the left side of the bearing slide rail 1-2, and the right rubber-coated bearing 2-7 is located on the right side of the bearing slide rail 1-2. In the initial position, the left rubber-coated bearing 2-6 does not contact the left flexible joint 2-1, and the right rubber-coated bearing 2-7 does not contact the right flexible joint 2-3.

[0042] The sleeve 1-1 is also provided with a groove 1-5, and the bearing slide rail 1-2 and the slider 1-3 are both set in the groove 1-5. The slider 1-3 is driven to make linear motion by a driver, which can be a motor.

[0043] like Figure 5As shown, the cutting and removing device 4 includes a cover plate 4-1, a wedge block 4-2, a blade 4-3, and a high-pressure air pipe 4-4. The cover plate 4-1 is located at the front of the sleeve 1-1. The wedge block 4-2 is provided on the cover plate 4-1, and the blade 4-3 is provided on the wedge block 4-2. The blade 4-3 is located above the left claw 2-4 and the right claw 2-5. (Refer to...) Figure 5 As shown, the inclined block 4-2 is provided with a central circular hole, and the high-pressure air pipe 4-4 is set in the central circular hole. The extension direction of the pipe hole of the high-pressure air pipe 4-4 is parallel to the inclined surface of the inclined block 4-2. The high-pressure air pipe 4-4 is used to deliver high-pressure gas to the laser emission hole of the fiber optic photoelectric sensor 5, which can remove fruit stem residue and other debris and prevent the sensor from being blocked.

[0044] The main body 2-2 and the cover plate 4-1 are made of stainless steel, while the movable base 1 is made of aluminum alloy to ensure the durability and strength of the equipment.

[0045] Reference Figure 2 , 3 As shown in Figure 4, the flexible clamping structure includes a left flexible joint 2-1, a right flexible joint 2-3, a left claw 2-4, a right claw 2-5, a left rubber-coated bearing 2-6, a right rubber-coated bearing 2-7, and a precision force measuring device. The tail end of the left flexible joint 2-1 is connected to the body 2-2, and the top end of the left flexible joint 2-1 is connected to the left claw 2-4. The left rubber-coated bearing 2-6 is mounted on the movable base 1 and can fit against the outer side of the left flexible joint 2-1. The outer side of the left flexible joint 2-1 is an arc surface. The tail end of the right flexible joint 2-3 is connected to the body 2-2, and the top end of the right flexible joint 2-3 is connected to the right claw 2-5. The right rubber-coated bearing 2-7 is mounted on the movable base 1 and can fit against the outer side of the right flexible joint 2-3. The outer side of the right flexible joint 2-3 is an arc surface. That is, the outer side of the left flexible joint 2-1 cooperates with the left rubber-coated bearing 2-6, and the outer side of the right flexible joint 2-3 cooperates with the right rubber-coated bearing 2-7, respectively, to form a linear cam structure, ensuring smooth movement. Taking the left flexible joint 2-1 as an example, during operation, in the initial position, the left rubber-coated bearing 2-6 is not in contact with the left flexible joint 2-1. As the slider 1-3 moves backward, the left rubber-coated bearing 2-6 fits against the arc surface of the outer side of the left flexible joint 2-1 and moves along the arc surface. The left rubber-coated bearing 2-6 squeezes the left flexible joint 2-1, causing the left flexible joint 2-1 to deform. During the operation of the right flexible joint 2-3, the left flexible joint 2-1, the left flexible joint 2-1, and the right flexible joint 2-3 deform to achieve clamping of the left claw 2-4 and the right claw 2-5.

[0046] The left flexible joint 2-1 and the right flexible joint 2-3 are made of 304 stainless steel.

[0047] Among them, the left claw 2-4 and the right claw 2-5, and the left flexible joint 2-1 and the right flexible joint 2-3 are arranged symmetrically, and have the same function and structure.

[0048] The front part of the left claw 2-4 and the front part of the right claw 2-5 are respectively provided with grooves for installing the fiber optic through-beam sensor 5. The fiber optic through-beam sensor 5 is used to detect whether the fruit stem enters the clamping range of the left claw 2-4 and the right claw 2-5.

[0049] Both the left flexible joint 2-1 and the right flexible joint 2-3 are provided with slots 2-8, which are I-shaped, to create physical space for the deformation of the left flexible joint 2-1 and the right flexible joint 2-3. The flexible joints use soft connections to achieve flexibility.

[0050] Continue to refer to Figure 2 , 3 As shown in Figure 4, the precision force measuring device is mounted on the body 2-2. The precision force measuring device includes a first strain gauge 3-1, a second strain gauge 3-2, and a third strain gauge 3-3. The first strain gauge 3-1 is mounted on the upper surface of the body 2-2. Along the moving direction of the clamping device 2, an opening groove 6 is provided on the body 2-2. The second strain gauge 3-2 is mounted in the opening groove 6. The third strain gauge 3-3 is mounted on the side of the body 2-2.

[0051] in,

[0052] The function of the first strain gauge 3-1 is to measure the weight of the fruit;

[0053] The function of the second strain gauge 3-2 is to prevent collisions with obstacles in front and behind when the clamping device 2 moves back and forth.

[0054] The function of the third strain gauge 3-3 is to prevent collisions with obstacles on the left and right sides;

[0055] The left claw tip 2-4 is indirectly connected to the precision force measuring device at the rear via the left flexible joint 2-1, and the right claw tip 2-5 is indirectly connected to the precision force measuring device at the rear via the right flexible joint 2-3.

[0056] Continue to refer to Figure 2 , 3 As shown in Figure 4, the main body 2-2 is also provided with a first amplification structure 3-4, a second amplification structure 3-5 and a third amplification structure 3-6. The first amplification structure 3-4, the second amplification structure 3-5 and the third amplification structure 3-6 are all hollowed-out figure-eight shapes, which further enhance the sensitivity of the first strain gauge 3-1, the second strain gauge 3-2 and the third strain gauge 3-3.

[0057] The first amplification structure 3-4 is disposed on the side of the main body 2-2, and the first strain gauge 3-1 is disposed in front of the first amplification structure 3-4.

[0058] The second magnified structure 3-5 is disposed on the upper surface of the body 2-2, and the second magnified structure 3-5 is located above the second strain gauge 3-2, that is, the second strain gauge 3-2 is installed in front of the second magnified structure 3-5.

[0059] The third amplification structure 3-6 is disposed on the upper surface of the body 2-2, and the third amplification structure 3-6 is located above the third strain gauge 3-3, that is, the third strain gauge 3-3 is installed directly in front of the third amplification structure 3-6.

[0060] The driver, the fiber optic through-beam sensor 5, the first strain gauge 3-1, the second strain gauge 3-2, and the third strain gauge 3-3 are all connected to the controller to achieve electronic control.

[0061] Work process:

[0062] Taking a strawberry as an example, as the end effector gradually approaches the strawberry, and the strawberry stem enters the opening range of the left claw 2-4 and the right claw 2-5, the fiber optic sensor 5 transmits a signal to the controller. At this time, the gripping device 2 moves backward (e.g., ...). Figure 1 (The direction of movement is shown), while the sleeve 1-1 remains fixed. As the left rubber-coated bearing 2-6 and the right rubber-coated bearing 2-7 exert pressure on the left flexible joint 2-1 and the right flexible joint 2-3 respectively, the left flexible joint 2-1 and the right flexible joint 2-3 deform, causing the left claw 2-4 and the right claw 2-5 to approach and close together, thus firmly clamping the fruit stem. Subsequently, the gripping device 2 continues to move backward on the carrying slide rail 1-2 via the slider 1-3, and the left claw 2-4 and the right claw 2-5 carry the fruit stem further backward to the blade 4-3, where the blade 4-3 completes the cutting of the fruit stem. When the end effector moves the separated strawberry to the designated position, the moving gripping device 2 moves forward (towards...). Figure 1 (The directions of movement are opposite to those shown). The left and right claws 2-4 and 2-5 automatically return to their open state under the elastic force of their respective movements. Simultaneously, high-pressure airflow is injected through the high-pressure air pipe 4-4 into the laser emission port of the fiber optic photoelectric sensor 5, removing residual debris and ensuring the continuous normal operation of the fiber optic photoelectric sensor 5. With the rapid action of the motor, the entire strawberry stem separation process can be completed instantly, greatly improving harvesting efficiency.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A self-cleaning end effector based on flexible joint force sensing, characterized in that, The device includes a clamping device, a movable base, and a cutting and cleaning device. The clamping device includes a body and a flexible clamping structure. The flexible clamping structure is provided on the body. The body is positioned above the movable base and can move on the movable base. The flexible clamping structure can deform to clamp the fruit stem. The cutting and cleaning device is positioned above the flexible clamping structure to cut the fruit stem clamped by the flexible clamping structure and clean the flexible clamping structure. The flexible clamping structure includes a left flexible joint, a right flexible joint, a left claw, a right claw, a left rubber-coated bearing, a right rubber-coated bearing, and a precision force measuring device. The tail end of the left flexible joint is connected to the main body, and the top end of the left flexible joint is connected to the left claw. The left rubber-coated bearing is mounted on the movable base and can fit against the outer side of the left flexible joint, which has an arc surface. The tail end of the right flexible joint is connected to the main body, and the top end of the right flexible joint is connected to the right claw. The right rubber-coated bearing is mounted on the movable base and can fit against the outer side of the right flexible joint, which also has an arc surface. The precision force measuring device is mounted on the main body. The left claw is connected to the precision force measuring device via the left flexible joint, and the right claw is connected to the precision force measuring device via the right flexible joint. The precision force measuring device includes a first strain gauge, a second strain gauge, and a third strain gauge. The first strain gauge is disposed above the main body. An opening groove is provided on the main body along the moving direction of the clamping device. The second strain gauge is disposed in the opening groove. The third strain gauge is disposed on the side of the main body. The movable base includes a sleeve, a bearing slide rail, a slider, and a bracket. The bearing slide rail is provided on the sleeve, and the slider is provided on the bearing slide rail. The slider is connected to the bottom of the main body through the bracket. The left rubber-coated bearing and the right rubber-coated bearing are respectively provided on the sleeve, and the left rubber-coated bearing is provided on the left side of the bearing slide rail, and the right rubber-coated bearing is provided on the right side of the bearing slide rail. The cutting and removing device includes a cover plate, a wedge block, a blade, and a high-pressure air pipe. The cover plate is located at the front of the sleeve, and the wedge block is provided on the cover plate. The blade is provided on the wedge block and is located above the left and right claws. A circular hole is provided in the center of the cover plate, and the high-pressure air pipe is located in the circular hole. The extension direction of the pipe hole of the high-pressure air pipe is parallel to the inclined surface of the wedge block.

2. The self-cleaning end effector based on flexible joint force sensing according to claim 1, characterized in that, Both the left flexible joint and the right flexible joint are provided with slots.

3. The self-cleaning end effector based on flexible joint force sensing according to claim 2, characterized in that, The slot is H-shaped.

4. The self-cleaning end effector based on flexible joint force sensing according to claim 3, characterized in that, The gripping device also includes fiber optic through-beam sensors, which are respectively disposed at the tips of the left and right claws.

5. The self-cleaning end effector based on flexible joint force sensing according to claim 4, characterized in that, The main body is also provided with multiple magnification structures. The first strain gauge, the second strain gauge and the third strain gauge are respectively installed in front of the magnification structure. The magnification structure is a hollow figure-eight shape.

6. The self-cleaning end effector based on flexible joint force sensing according to claim 5, characterized in that, The sleeve is also provided with a groove, and the bearing slide rail and the slider are both disposed in the groove.

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