Hydraulically driven variable stiffness soft gripper

Abstract

The present application relates to a kind of hydraulic drive variable stiffness soft gripper, including flexible finger, fixed support, slider, gear, oil pipe, lower oil pipe, piston driving device, one-way shunt valve, two-way shunt valve and motor;The flexible finger is arranged in the upper end of slider, the slider is slidably connected with fixed support, the gear is engaged with the rack on slider, the piston driving device is fixed in the lower end of fixed support, one end of the upper oil pipe is connected with slider, the other end is connected with two-way shunt valve, one end of the lower oil pipe is connected with slider, the other end is connected with one-way shunt valve, the slider driving motor is connected with sun gear in fixed support, the sun gear is engaged with planetary gear, the planetary gear is engaged with rack, the piston driving motor is connected with piston driving device;The present application is simple in structure, can adjust the gripping force of gripper according to the weight of object, can bend finger more easily when gripping action, so as to realize the nondestructive gripping of object.

Description

Technical Field

[0001] This invention relates to the field of soft gripper technology, and more particularly to a hydraulically driven variable stiffness soft gripper. Background Technology

[0002] Soft grippers are made of flexible, deformable materials, offering greater adaptability. They can adapt to objects of various shapes, sizes, and surface properties without requiring specific grippers or claws. This adaptability makes soft grippers more flexible and versatile when handling different objects. Soft grippers have no sharp edges or mechanical parts, thus reducing scratches and damage to the object's surface upon contact. This makes soft grippers particularly suitable for fragile or surface-sensitive objects.

[0003] Currently available variable stiffness soft grippers are mostly driven by gas. By controlling the input gas pressure, the gripping force and bending degree of the soft gripper can be controlled. However, this method can result in insufficient gripping force. Moreover, current grippers are fixed to the base and cannot be adjusted to different sizes of objects, resulting in a narrow gripping range.

[0004] Therefore, in order to address the above problems, this invention proposes a hydraulically driven variable stiffness soft gripper that is simple to control, has a wide gripping force range, and can adjust the position of the fingers. Summary of the Invention

[0005] To address the aforementioned issues, this invention utilizes the design of a TPMS (Triple Period Minimal Curved Surface Structure) flexible biomimetic layer, a rigid layer, and an oil-filled variable stiffness layer to create a hydraulically driven variable stiffness soft gripper. This gripper provides sufficient gripping stiffness while effectively reducing the intensity of finger bending, and simultaneously ensuring the safety of the object being gripped.

[0006] The technical solution adopted in this invention is as follows:

[0007] The present invention discloses a hydraulically driven variable stiffness soft gripper, comprising a flexible finger, a fixed support, a slider, gears, an upper oil pipe, a lower oil pipe, a piston drive device, a first flow divider valve, a second flow divider valve, and a motor. The flexible finger is disposed on the upper end of the slider, the gear meshes with the rack on the slider, the piston drive device is fixed to the lower end of the fixed support, one end of the upper oil pipe is connected to the slider, and the other end is connected to the flow divider valve 2, one end of the lower oil pipe is connected to the slider, and the other end is connected to the flow divider valve 1, the slider drive motor is connected to the sun gear in the fixed support, the sun gear meshes with planet gears, the planet gears mesh with the rack, and the motor 2 is connected to the piston drive device.

[0008] The flexible finger comprises a silicone shell, a TPMS (three-period minimal surface structure) flexible bionic layer, a rigid layer, and an oil-filled variable stiffness layer, which are arranged sequentially inside the silicone shell from bottom to top; the TPMS (three-period minimal surface structure) flexible bionic layer is connected to the lower oil pipe through the oil passage inside the slider, the other end of the lower oil pipe is connected to the diversion valve 1, the diversion valve is connected to the piston drive device, and the piston drive device is driven by a motor;

[0009] The slider is installed in the groove of the fixed support. The lower end of the slider is connected to the rack. The rack meshes with the planetary gears. The planetary gears mesh with the sun gear. The sun gear is driven by a motor. The motor drives the sun gear to rotate, which in turn drives the planetary gears to rotate. The rotation of the planetary gears drives the rack to move linearly. The rack drives the slider to move linearly, thus enabling the fingers to grasp objects of different sizes.

[0010] The piston drive device includes two pistons, a gear, a rack, and a housing. The gear meshes with the rack, the rack is connected to the piston, and the piston is connected to the piston cylinder on the housing. Oil is injected into the piston cylinder. The motor drives the gear to rotate, and the gear drives the rack to make the piston fixed on the rack reciprocate. Under the push of the piston, the oil pushing and sucking actions are completed. There are two oil ports on the housing, which are connected to two diverter valves respectively.

[0011] The beneficial effects of this invention are:

[0012] 1. A sliding groove is provided on the fixed support, which allows the finger mounted on the slider to slide and adjust it;

[0013] 2. The sun gear driven by the motor drives the planetary gears to rotate, and the planetary gears drive the rack on the slider to reciprocate, so as to achieve stable sliding of the slider;

[0014] 3. The piston drive device can simultaneously perform oil suction and oil filling actions. When the oil-filled variable stiffness layer is filled with oil, it causes the finger to bend. When it is filled with oil, it causes the TPMS (three-period minimal surface structure) flexible bionic layer to contract, thereby reducing the bending strength of the finger for more stable gripping.

[0015] 4. When the fingers grasp an object, the TPMS (three-period minimal surface structure) flexible biomimetic layer can better conform to the object's surface based on the deformation capability of the TPMS structure, thereby realizing the biomimetic grasping of the object. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of a hydraulically driven variable stiffness soft gripper proposed in this invention.

[0017] Figure 2 yes Figure 1 Schematic diagram of the internal structure of the fixed support;

[0018] Figure 3 yes Figure 1 A schematic diagram of the cross-sectional structure of a moderately flexible finger;

[0019] Figure 4 yes Figure 1 Schematic diagram of the piston drive device;

[0020] Figure 5 yes Figure 4 Schematic diagram of the piston structure.

[0021] The attached diagrams are labeled as follows: 1-Fixed support; 2-Slider drive motor; 3-First diverter valve; 4-Reducer; 5-Piston drive motor; 6-Second diverter valve; 7-Planetary gear; 8-Slider; 9-Oil pipe; 10-Sun gear; 20-Piston drive device; 21-Rack; 22-Gear; 23-Guide pin; 24-Piston; 30-Flexible finger; 31-Oil-filled variable stiffness layer; 32-Rigid body; 33-Pin; 34-TPMS structure; 35-Rubber ball; 36-First oil port; 37-Second oil port. Detailed Implementation

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] It should be noted that in the description of this invention, the terms "upper", "lower", "top", "bottom", "one end", "the other end", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description, and do not mean that the device or element must have a specific orientation, or be constructed and operated in a specific orientation.

[0024] See appendix Figure 1-5This paper presents a specific structure of a hydraulically driven variable stiffness soft gripper proposed in this invention. The soft gripper includes a fixed support 1, a slider drive motor 2, a first diverter valve 3, a reducer 4, a piston drive motor 5, a second diverter valve 6, a planetary gear 7, a slider 8, an oil pipe 9, a sun gear 10, a piston drive device 20, a rack 21, a gear 22, a guide pin 23, a piston 24, a flexible finger 30, an oil-filled variable stiffness layer 31, a rigid body 32, a pin 33, a TPMS biomimetic structure layer 34, a rubber ball 35, a first oil port 36, and a second oil port 37. In this embodiment, three sliders 10 are evenly distributed on the upper end of the fixed support 1. Three flexible fingers 30 are mounted on each slider. The sliders have internal oil passages connected to oil ports 36 and 37 respectively. The two oil passage ends at the rear ends of the three sliders are connected to a second diversion valve 7 and a first diversion valve 3 via oil pipes. The second diversion valve 7 is connected to a piston drive device 20 via an oil pipe, and the first diversion valve 3 is connected to the piston drive device 20 via an oil pipe. The fixed support 1 contains a sun gear 9 connected to the slider drive motor 2. The sun gear 9 meshes with planetary gears 6, which in turn mesh with a rack on the slider 10. The slider drive motor 2 drives the sun gear 9 to rotate, which in turn drives the planetary gears 6 to rotate in the opposite direction. The planetary gears 6 drive the slider to perform linear motion, thereby adjusting the diameter of the object grasped by the gripper.

[0025] The piston drive device 20 includes a rack 21, a gear 22, a piston 23, and a flexible finger 30. One end of the rack 21 is connected to the piston 23, and the other end is connected to the guide pin 23. The gear 22 drives the two pistons to make opposing linear movements through the reducer 4 and the piston drive motor 5. When the piston pushes the hydraulic oil, it produces a dual effect of filling and absorbing oil. The piston drive device 20 causes the oil-filled variable stiffness layer 31 and the TPMS bionic structure layer 34 in the flexible finger 30 to expand or compress. When the oil-filled variable stiffness layer 31 expands, the soft gripper bends under the expansion. The TPMS bionic structure layer 34 absorbs oil and compresses. Under the contraction, the bending strength of the soft gripper is reduced. The rubber ball 35 on the TPMS bionic structure layer 34 protrudes more and more under the contraction. When grasping an object, the TPMS bionic structure layer 34 can fit tightly with the surface of the object being grasped, realizing the bionic grasping of the object. At the same time, the rubber ball 35 increases the friction.

[0026] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A hydraulically driven variable stiffness soft gripper, characterized in that: The soft gripper includes a fixed support, a slider, an upper oil pipe, a lower oil pipe, a piston drive device, a first diversion valve, a second diversion valve, a slider drive motor, a piston drive motor, flexible fingers, a sun gear, planetary gears, and a first rack. The fixed support houses the sun gear, planetary gears, and slider. The flexible fingers are positioned at the upper end of the slider. The piston drive device is fixed to the lower end of the fixed support. One end of the upper oil pipe is connected to the slider, and the other end is connected to the second diversion valve. One end of the lower oil pipe is connected to the slider, and the other end is connected to the first diversion valve. The slider drive motor is connected to the sun gear, which meshes with the planetary gears. The planetary gears mesh with the first rack. The piston drive motor is connected to the piston drive device; the flexible finger includes a silicone shell, a TPMS flexible bionic layer, a rigid layer, and an oil-filled variable stiffness layer, which are arranged sequentially from bottom to top inside the silicone shell; the TPMS flexible bionic layer is connected to the lower oil pipe through an oil passage inside the slider, and the other end of the oil pipe is connected to the first diversion valve, which is connected to the piston drive device, which is driven by a piston drive motor; the oil-filled variable stiffness layer is connected to the upper oil pipe through another oil passage inside the slider, and the other end of the upper oil pipe is connected to the second diversion valve, which is connected to the piston drive device. The slider is installed in the groove of the fixed support. The lower end of the slider is connected to the first rack. The first rack meshes with the planetary gears. The planetary gears mesh with the sun gear. The sun gear is driven by the slider drive motor. The slider drive motor drives the sun gear to rotate, which in turn drives the planetary gears to rotate. The rotation of the planetary gears drives the first rack to move linearly. The first rack drives the slider to move linearly, thus enabling the fingers to grasp objects of different sizes.

2. The hydraulically driven variable stiffness soft gripper according to claim 1, characterized in that: The piston drive device includes two pistons, a gear, two second racks, two guide pins, and a housing. The gear meshes with the two second racks simultaneously. One end of each second rack is connected to one of the two pistons, and the other end is connected to one of the two guide pins. The piston drive motor drives the gear to rotate, and the gear drives the two second racks to make opposing linear movements, causing the two pistons fixed on the two second racks to make opposing reciprocating movements. Under the push of the two pistons, the oil pushing and oil suction actions are completed. The housing has two oil ports, which are connected to the first diversion valve and the second diversion valve, respectively.

3. The hydraulically driven variable stiffness soft gripper according to claim 1, characterized in that: The TPMS flexible biomimetic layer, rigid layer, and oil-filled variable stiffness layer are not interconnected.

4. The hydraulically driven variable stiffness soft gripper according to claim 1, characterized in that: When the flexible finger grasps, the oil-filled variable stiffness layer expands and the TPMS flexible biomimetic layer contracts under the action of the piston drive device.

5. A hydraulically driven variable stiffness soft gripper according to claim 1, characterized in that: The TPMS flexible biomimetic layer inside the flexible finger has a primitive structure and is 3D printed from silicone. This structure has a large amount of deformation and resilience, which can fit the surface of the object to be grasped to the greatest extent, so as to achieve biomimetic grasping.

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