A force-controlled picking end effector

Abstract

The present invention relates to a force-controlled picking end effector, which includes a finger driving component and a finger force control component; the finger driving component includes a base, a power device and a movable device, the movable device is slidably installed on the base, there are two groups of movable devices, and the two groups of movable devices approach or move away from each other along the base under the action of the power device; the finger force control component includes a clamping mechanism and a force control mechanism, the clamping mechanism includes a linear bearing bracket, a moving shaft and a clamping plate, the force control mechanism includes a photoelectric switch and an induction component. When the finger driving component drives the finger force control component to clamp an object to be clamped, a relative displacement occurs between the moving shaft and the linear bearing bracket, causing the photoelectric switch and the induction component to approach, triggering the photoelectric switch, controlling the operation of the power device, and stopping the two groups of movable devices connected to the clamping mechanism from approaching. The present invention is used for picking fruits with high quality requirements and difficult picking, such as brown mushrooms, to achieve damage-free picking.

Description

Technical Field

[0001] The present invention relates to the field of agricultural automated harvesting, and in particular to a force-controlled harvesting end effector. Background Art

[0002] Brown mushrooms, also known as beefsteak mushrooms, originated in Italy and first grew in grasslands in Europe and America. They are high-end mushrooms in Western cuisine and have extremely high nutritional, health and medical value. At present, large-scale brown mushroom cultivation and breeding houses have been built in Yangzhou, my country, but the harvesting of brown mushrooms still needs to be done manually, and the development of the end effector for brown mushroom harvesting is relatively difficult:

[0003] (1) High force control requirements for picking operations: In order to ensure the quality of brown mushrooms, the end effector must control the picking clamping force to achieve non-destructive picking operations. At the same time, in the early stage of measuring the clamping force at the picking site, the end effector should have the function of conveniently and flexibly adjusting the clamping force within a certain range to shorten the clamping force setting time. The commercial integrated force control automatic unit for industrial automation applications is expensive, and its performance parameters, weight and application scenarios are often incompatible with the picking requirements. All these factors are not conducive to its market application. Therefore, it is more reasonable to develop a low-cost controllable force unit suitable for brown mushroom picking operations.

[0004] (2) Rationalization of the design of the picking action mechanism: Whether the design and manufacture of the picking action mechanism are reasonable directly affects the success rate of picking. Up to now, there are two main types of action execution methods of the fruit and vegetable picking end effector: action twisting type and knife cutting type. The corresponding mechanism of the action twisting type design first clamps and grasps the fruit or sucks it with negative pressure, and then uses the rotation of the robot wrist joint in two vertical directions to simulate the action of people twisting the fruit stalk. The object of its operation requires that the fruit stalk is easy to separate from the fruit branch, and at the same time, the size of the clamping or adsorption force needs to be strictly controlled, otherwise it is very easy to damage the fruit. The fruit stalk cutting type mainly uses a motor or cylinder to drive the blade to rotate or the scissors to directly cut the fruit stalk. When using the blade to rotate to cut the fruit stalk, this method requires clear detection of the position or complexity of the fruit stalk, which increases the cost. Summary of the invention

[0005] The purpose of the present invention is to provide a force-controlled picking end effector with adjustable clamping force, which is used for picking fruits with high quality requirements and great picking difficulty, such as brown mushrooms, to achieve non-destructive picking.

[0006] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0007] A force-controlled picking end effector comprises a finger-gripping driving component and a finger-gripping force-control component;

[0008] The finger driving component described above includes a base, a power device, and a movable device. The movable device is slidably installed on the base. There are two groups of movable devices, and the two groups of movable devices approach or move away from each other along the base under the action of the power device;

[0009] The finger force control component described above includes a clamping mechanism and a force control mechanism. The clamping mechanism includes a linear bearing bracket, a moving shaft, and a clamping plate. The force control mechanism includes a photoelectric switch and an induction component; each group of movable devices is connected to a clamping mechanism; a linear bearing is provided inside the linear bearing bracket, and the moving shaft is movably installed inside the linear bearing. One end of the moving shaft is a shaft portion, and a spring and a clamping plate are sequentially sleeved on the shaft portion toward the shaft end; the other end of the moving shaft is connected to a photoelectric switch through a connecting component, and the photoelectric switch is signal-connected to the power device. An induction component corresponding to the photoelectric switch is installed on the linear bearing bracket; when the finger driving component drives the finger force control component to clamp the object to be clamped, a relative displacement is generated between the moving shaft and the linear bearing bracket, causing the photoelectric switch and the induction component to approach, triggering the photoelectric switch, and controlling the operation of the power device to stop the two groups of movable devices connected to the clamping mechanism from approaching.

[0010] To optimize the above technical solution, the specific measures taken also include:

[0011] The movable device includes two groups of corresponding sliders and linear guide slider modules, and the linear guide slider modules are respectively connected to the lower ends of the sliders; the base is a horizontal strip-shaped seat, and left and right direction guides are provided along the lower part of the base. The linear guide slider modules are movably installed on the guides of the base through the sliders, and the linear bearing bracket is fixedly installed at the bottom of the linear guide slider modules.

[0012] Further, two groups of pulleys and pulley shafts are provided on the base. The two groups of pulleys are respectively installed at the left and right ends of the base through the corresponding pulley shafts. A steel wire rope is sleeved outside the two groups of pulleys. The two sliders are respectively located on the front and rear sides of the base. A wire clamping bracket is connected to the inner side of each slider, and the wire clamping bracket clamps the steel wire rope loop. One of the sliders is connected to the power device.

[0013] Further, the power device includes a linear motor, a motor fixing seat, and a screw rod bracket. A motor fixing seat is provided on one side of the base, a driving fork is installed on the slider on this side, a screw rod bracket is fixed on the driving fork, the linear motor is installed on the motor fixing seat, and the output shaft of the linear motor is fixed in the screw rod bracket.

[0014] Further, the connecting component is a cage, the cage is installed at the other end of the moving shaft, and the photoelectric switch is installed on one side of the cage.

[0015] Furthermore, the induction component includes a light-shielding plate and an induction bracket. The light-shielding plate is installed at the bottom of the linear bearing bracket, and the induction bracket is installed on the light-shielding plate. When the moving shaft is in the initial position, the induction bracket is located far from the photoelectric switch. When clamping an object to be clamped, the moving shaft and the linear bearing bracket generate relative displacement, and the photoelectric switch on the cage and the induction bracket approach each other.

[0016] Furthermore, the other end of the moving shaft has a convex portion with a threaded through-hole. An adjusting screw is installed in the threaded through-hole. The adjusting screw passes through the convex portion of the moving shaft, and its end abuts against the linear bearing bracket, thereby adjusting the pre-tightening force of the adjusting spring by tightening or loosening the adjusting screw.

[0017] Furthermore, the initial distance between the photoelectric switch and the induction component is set at an appropriate distance so that a suitable non-destructive clamping force is generated between the clamping plates when clamping an object to be clamped.

[0018] As a preferred solution, a U-shaped card slot is provided on the light-shielding plate. The lower end of the induction bracket passes through the U-shaped card slot and is fastened at the bottom in the U-shaped card slot. The initial distance between the induction bracket and the photoelectric switch is adjusted by adjusting the position of the induction bracket in the U-shaped card slot.

[0019] As a preferred solution, it further includes an end connecting bracket. The end connecting bracket is installed on the base and is used to connect the force-controlled picking end effector to the robotic arm.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] The force-controlled picking end effector of the present invention can change the distance between the clamping plates by adjusting the position between the photoelectric switch and the induction component, thereby realizing the change of the clamping force.

[0022] The force-controlled picking end effector of the present invention can realize the synchronous picking action of the force-controlled components of the two-side clamping fingers through the structural design of the linear motor driving the pulley and the steel wire rope, with a simple structure and smooth operation.

[0023] In the present invention, the force-controlled component of the clamping finger uses an adjusting screw to adjust its position on the linear bearing bracket to change the spring deformation degree at the minimum load of the spring, and thus the pre-tightening force can be changed.

[0024] The structure of the present invention can be connected and matched with a robotic arm through an end connecting bracket installed on the upper side of the base.

[0025] During application, debugging is carried out before the picking operation. After the pre-tightening force is adjusted in advance, the time of the picking action will be reduced, improving the picking efficiency; after the clamping force is adjusted in advance, after picking the target, the damage to the target caused by the picking action can be reduced, improving the picking accuracy. At the same time, the force control scheme is simple, the operation is convenient, there is no cumbersome force control algorithm, and the control difficulty is low.

[0026] The use of the structure of the present invention can replace high-cost servo force control, and at the same time has the advantages of simple force control operation, convenient maintenance, low manufacturing cost, strong practicability, etc., and is easy to be popularized in the market. Brief Description of the Drawings

[0027] Figure 1 : Schematic diagram of the overall structure of the force control picking end effector of the present invention.

[0028] Figure 2 : Figure 1 Schematic diagram of the enlarged structure of part A in

[0029] Figure 3 : Schematic diagram of the structure of the finger driving component.

[0030] Figure 4 : Schematic diagram of the structure of the finger force control component.

[0031] In the figure: 101-linear motor, 102-motor fixing seat, 103-wire clamping bracket 1, 104-screw rod bracket, 105-end connecting bracket, 106-driving fork bracket, 107-linear guide rail slider module, 108-wire clamping bracket 2, 109-steel wire rope, 110-pulley shaft, 111-pulley, 112-base, 201-clamping plate, 202-light shielding sheet, 203-induction bracket, 204-photoelectric switch, 205-retaining cage, 206-adjusting screw, 207-linear bearing bracket, 208-moving shaft, 209-spring, 210-linear bearing. Detailed Description of the Preferred Embodiments

[0032] The above content of the present invention will be further described in detail below in the form of embodiments, but it should not be understood that the scope of the above subject matter of the present invention is limited to the following embodiments. All technologies implemented based on the above content of the present invention belong to the scope of the present invention.

[0033] In the description of the present invention, it should also be noted that:

[0034] The orientation or positional relationship therein is based on the relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0035] The present invention provides a force control picking end effector, as Figure 1 shown, including a finger driving component and a finger force control component;

[0036] The finger clamping driving component includes a base 112, a power device and a movable device. The movable device is slidably mounted on the base 112. There are two groups of movable devices, and the two groups of movable devices approach or move away from each other along the base 112 under the action of the power device;

[0037] The finger clamping force control component includes a clamping mechanism and a force control mechanism. The clamping mechanism includes a linear bearing holder 207, a moving shaft 208 and a clamping plate 201. The force control mechanism includes a photoelectric switch 204 and an induction component; Each group of movable devices is connected to a clamping mechanism; As Figure 2 shown, there is a linear bearing 210 inside the linear bearing holder 207. The moving shaft 208 is movably installed inside the linear bearing 210. One end of the moving shaft 208 is a shaft part, and a spring 209 and a clamping plate 201 are sequentially sleeved on the shaft part towards the shaft end; The other end of the moving shaft 208 is connected with a photoelectric switch 204 through a connecting component. The photoelectric switch 204 is signal-connected to the power device. An induction component corresponding to the photoelectric switch 204 is installed on the linear bearing holder 207. In the embodiment, the connecting component is a cage 205. The cage 205 is installed at the other end of the moving shaft 208, and the photoelectric switch 204 is installed on one side of the cage 205.

[0038] When the finger clamping driving component drives the finger clamping force control component to clamp the object to be clamped, the moving shaft 208 and the linear bearing holder 207 generate relative displacement, so that the photoelectric switch 204 and the induction component approach each other, trigger the photoelectric switch 204, control the operation of the power device, and stop the two groups of movable devices connected to the clamping mechanism from approaching.

[0039] The movable device includes two groups of corresponding sliders and a linear guide rail slider module 107. The linear guide rail slider modules 107 are respectively connected to the lower ends of the sliders; The base 112 is a horizontal strip-shaped seat. Guides in the left-right direction are provided along the lower part of the base 112. The linear guide rail slider module 107 is movably installed on the guide rail of the base 112 through the slider, and the linear bearing holder 207 is fixedly installed at the bottom of the linear guide rail slider module 107.

[0040] As Figure 3 shown, two groups of pulleys 111 and pulley shafts 110 are provided on the base 112. The two groups of pulleys 111 are respectively installed at the left and right ends of the base 112 through the corresponding pulley shafts 110. A steel wire rope is sleeved outside the two groups of pulleys 111. As the pulley shafts are installed on both sides of the base, the steel wire rope is sleeved on the pulleys on both sides, so that the pulleys on both sides transmit motion and power through the steel wire rope.

[0041] In the embodiment, the two sliders are respectively located on the front and rear side surfaces of the base 112. A wire clamping bracket is connected to the inner side of each slider. The wire clamping bracket clamps the steel wire rope loop, and one of the sliders is connected to the power device.

[0042] The power device includes a linear motor 101, a motor fixing base 102, and a screw rod frame 104. A motor fixing base 102 is provided on one side of the base 112. A driving fork frame 106 is installed on the slider of this side. A screw rod frame 104 is fixed on the driving fork frame 106. The linear motor 101 is installed on the motor fixing base 102, and the output shaft of the linear motor 101 is fixed in the screw rod frame 104.

[0043] As Figure 4 shown, the induction component includes a light-shielding plate 202 and an induction bracket 203. The light-shielding plate 202 is installed at the bottom of the linear bearing bracket 207, and an induction bracket 203 is installed on the light-shielding plate 202; when the moving shaft 208 is in the initial position, the induction bracket 203 is located farther away from the photoelectric switch 204. When clamping an object to be clamped, a relative displacement is generated between the moving shaft 208 and the linear bearing bracket 207, and the photoelectric switch 204 on the cage 205 approaches the induction bracket 203.

[0044] The other end of the moving shaft 208 has a convex portion with a threaded through hole. An adjusting screw 206 is installed in the threaded through hole. The adjusting screw 206 passes through the convex portion of the moving shaft 208, and its end abuts against the linear bearing bracket 207, and the pre-tightening force of the adjusting spring 209 is adjusted by tightening or loosening the adjusting screw 206.

[0045] Specifically, the adjusting screw is installed in the threaded hole of the convex portion of the moving shaft. The shaft portion of the moving shaft is sequentially loaded with a spring and a gasket. The linear bearing bracket will tightly abut against the adjusting screw under the action of the spring. Finally, a clamping plate is pressed on the end face of the shaft portion and connected with a fastener. In this way, the height adjustment of the spring in the minimum load state can be achieved by using the adjusting screw, thereby realizing the adjustment of the pre-tightening force.

[0046] The initial distance between the photoelectric switch 204 and the induction component is set at an appropriate distance so that a suitable non-destructive clamping force is generated between the clamping plates 201 when clamping an object to be clamped. Specifically, a U-shaped card slot is provided on the light-shielding plate 202. The lower end of the induction bracket 203 passes through the U-shaped card slot and is fastened at the bottom in the U-shaped card slot. The initial distance between the induction bracket 203 and the photoelectric switch 204 is adjusted by adjusting the position of the induction bracket 203 in the U-shaped card slot.

[0047] In the embodiment, the induction bracket is installed in the U-shaped groove of the light-shielding sheet and its position can be adjusted. The photoelectric switch is installed on the side of the linear bearing bracket. When the induction bracket moves into the photoelectric switch, the movement driven by the linear motor stops. By adjusting the distance between the induction bracket and the photoelectric switch, the distance that the linear motor drives the linear bearing bracket to compress the spring will change, thereby realizing the adjustment of the clamping force and achieving non-destructive clamping.

[0048] It further includes an end connecting bracket which is installed on the base 112 and used to connect the force-controlled picking end effector to the robotic arm.

[0049] The present invention is used for picking fruits with high quality requirements and great picking difficulty, such as brown mushrooms, to achieve damage-free picking. During application, prior to the picking operation, debugging is first carried out. After the pre-tightening force is debugged in advance, the time of the picking action will be reduced, improving the picking efficiency; after the clamping force is debugged in advance, after picking the target, the damage to the target caused by the picking action can be reduced, improving the picking accuracy.

[0050] The above are only the preferred embodiments of the present invention and do not impose any form of limitation on the present invention. Any person skilled in the relevant art, without departing from the scope of the technical solution of the present invention and based on the technical essence of the present invention, any simple modification, equivalent replacement, and improvement made to the above embodiments still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A force-controlled picking end effector, characterized in that: It includes finger clamping drive components and finger clamping force control components; The finger clamping drive components include a base (112), a power device and a movable device. The movable device is slidably mounted on the base (112). There are two groups of movable devices, and the two groups of movable devices approach or move away from each other along the base (112) under the action of the power device; The finger clamping force control components include a clamping mechanism and a force control mechanism. The clamping mechanism includes a linear bearing bracket (207), a moving shaft (208) and a clamping plate (201). The force control mechanism includes a photoelectric switch (204) and an induction component. Each group of movable devices is connected to a clamping mechanism. The linear bearing bracket (207) is provided with a linear bearing (210), and the moving shaft (208) is movably mounted in the linear bearing (210). One end of the moving shaft (208) is a shaft part, and a spring (209) and a clamping plate (201) are sequentially sleeved on the shaft part towards the shaft end. The other end of the moving shaft (208) is connected to a photoelectric switch (204) through a connecting component. The photoelectric switch (204) is signal-connected to the power device, and an induction component corresponding to the photoelectric switch (204) is mounted on the linear bearing bracket (207). When the finger clamping drive components drive the finger clamping force control components to clamp an object to be clamped, the moving shaft (208) and the linear bearing bracket (207) generate a relative displacement, so that the photoelectric switch (204) and the induction component approach each other, triggering the photoelectric switch (204) to control the operation of the power device, and stopping the two groups of movable devices connected to the clamping mechanism from approaching; The movable device includes two groups of corresponding sliders and a linear guide rail slider module (107). The linear guide rail slider modules (107) are respectively connected to the lower ends of the sliders. The base (112) is a horizontal strip-shaped seat, and left and right direction guide rails are provided along the lower part of the base (112). The linear guide rail slider module (107) is movably mounted on the guide rail of the base (112) through the slider, and the linear bearing bracket (207) is fixedly mounted at the bottom of the linear guide rail slider module (107); Two groups of pulleys (111) and pulley shafts (110) are provided on the base (112). The two groups of pulleys (111) are respectively mounted on the left and right ends of the base (112) through the corresponding pulley shafts (110). A steel wire rope loop is sleeved outside the two groups of pulleys (111). The two sliders are respectively located on the front and rear sides of the base (112). A wire clamping bracket is connected to the inner side of each slider, and the wire clamping bracket clamps on the steel wire rope loop. One of the sliders is connected to the power device; The power device includes a linear motor (101), a motor fixing seat (102) and a screw rod bracket (104). A motor fixing seat (102) is provided on one side of the base (112). A driving fork (106) is mounted on the slider on this side. A screw rod bracket (104) is fixed on the driving fork (106). The linear motor (101) is mounted on the motor fixing seat (102), and the output shaft of the linear motor (101) is fixed in the screw rod bracket (104).

2. The force-controlled harvesting end effector according to claim 1, characterized in that: The connecting component described above is a cage (205), the cage (205) is installed at the other end of the moving shaft (208), and the photoelectric switch (204) is installed on one side of the cage (205).

3. The force-controlled picking end effector according to claim 1, wherein: The induction component described above includes a light shielding plate (202) and an induction bracket (203). The light shielding plate (202) is installed at the bottom of the linear bearing bracket (207), and the induction bracket (203) is installed on the light shielding plate (202); when the moving shaft (208) is in the initial position, the induction bracket (203) is located far away from the photoelectric switch (204). When clamping the object to be clamped, a relative displacement occurs between the moving shaft (208) and the linear bearing bracket (207), and the photoelectric switch (204) on the cage (205) approaches the induction bracket (203).

4. The force-controlled picking end effector according to claim 1, wherein: The other end of the moving shaft (208) has a convex portion, the convex portion has a threaded through hole, and an adjusting screw (206) is installed in the threaded through hole. The adjusting screw (206) passes through the convex portion of the moving shaft (208), and its end abuts against the linear bearing bracket (207), and the pre-tightening force of the adjusting spring (209) is adjusted by tightening or loosening the adjusting screw (206).

5. The force-controlled picking end effector according to claim 1, wherein: The initial distance between the photoelectric switch (204) and the induction component is set at an appropriate distance so that a suitable non-destructive clamping force is generated between the clamping plates (201) when clamping the object to be clamped.

6. The force-controlled picking end effector according to claim 3, wherein: The light shielding plate (202) is provided with a U-shaped card slot. The lower end of the induction bracket (203) passes through the U-shaped card slot, and the bottom is fastened in the U-shaped card slot by a nut. The initial distance between the induction bracket (203) and the photoelectric switch (204) is adjusted by adjusting the position of the induction bracket (203) in the U-shaped card slot.

7. The force-controlled picking end effector according to claim 1, wherein: It also includes an end connecting frame, and the end connecting frame is installed on the base (112) and is used to connect the force-controlled picking end effector to the robotic arm.

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