Paper folding type underwater gripper based on HASEL driver and parameter design method

Abstract

The invention discloses a paper folding type underwater gripper based on HASEL drivers and a parameter design method.The paper folding type underwater gripper comprises a driver set and a gripper body, the gripper body comprises a connecting plate, bending joints, bearing frameworks and gripping fingertips, the bearing frameworks are connected through the bending joints to form a Z-shaped gripper framework, and the included angle of the bending joints is adjustable; the driver group comprises a plurality of single drivers, each single driver comprises a strain film and an electrified electrode, the single drivers are connected through a folding film, and the driver group is folded at the folding film to form a Z-shaped paper folding structure; the driver sets are installed on the inner side and the outer side of a gripper framework of the gripper, and the strain film is located in an included angle space formed by the bearing framework and the bending joint. When the driver set on the outer side is started, the strain film on the outer side expands, the included angle on the outer side of the gripper framework becomes large, and the grippers are bent inwards to enter the grabbing state; similarly, when the driver group on the inner side is started, the gripper is bent outwards and enters a loosening state.

Description

Technical Field

[0001] The present invention relates to the field of soft robots, and in particular to an origami-type underwater gripper based on a HASEL driver and a parameter design method. Background Art

[0002] With the increasing demand for underwater operations, the application of underwater robots and grasping equipment in the fields of ocean exploration, deep-sea exploration, and seabed repair has gradually increased. Traditional underwater grippers mostly rely on hydraulic or electric drives. Although they have strong grasping capabilities and adaptability, these systems usually have disadvantages such as large size, high energy consumption, and complex structure. In deep-sea environments, traditional systems often face problems such as volume limitations, difficulty in energy transmission, and insufficient operating precision.

[0003] In recent years, origami technology has been gradually applied to the design of soft robots and underwater grasping devices due to its simple structure, light weight and efficient space utilization. Origami structures can have high rigidity and deformability while maintaining light weight, and are particularly suitable for fine grasping tasks in complex underwater environments. At the same time, Hasel actuators, as a new type of intelligent drive technology, achieve efficient motion drive through the deformation of electrically controlled materials, and have high energy efficiency density and precise force control characteristics.

[0004] Patent 202310377075.0 discloses a variable-length flexible pneumatic soft gripper, including a gripper fixing platform, a finger winding mechanism and a flexible finger, wherein the finger winding mechanism is mounted on the gripper fixing platform, and the flexible finger is mounted on the finger winding mechanism, and the finger winding mechanism can adjust the length of the flexible finger. The finger length can be flexibly adjusted according to the size of the grasped object to achieve the best grasping posture. However, the soft cavity is used as the grasping force point, and the load capacity is poor. The grasping and releasing process requires waiting for the medium to change in the cavity, the speed is slow, and the power source control requirements are high.

[0005] In the article "A Soft, Fast and Versatile Electrohydraulic Gripper with Capacitive Object Size Detection", a self-sensing electrohydraulic bending gripper is proposed. The gripper is driven by a HASEL driver and has capacitive pickup verification and object size detection functions. The gripper is fast, has low power consumption, and can pick up a variety of objects through simple binary electrical control. However, when the gripper releases the object, the driver cannot immediately return to the initial state, resulting in a long release time and affecting the second grasping range.

[0006] Soft grippers generally use soft chambers to carry loads, which results in insufficient gripping force. Traditional pneumatic and liquid grippers need to wait for the medium to be filled before they can grip, and their response speed is slow. Grippers using HASEL drives generally have a problem with slow drive recovery speeds, resulting in a long release time, which affects the gripping range. Summary of the invention

[0007] Purpose of the invention: The present invention aims to provide an origami-type underwater gripper based on a HASEL actuator with sufficient gripping force and rapid recovery; another purpose of the present invention is to provide a parameter design method for an origami-type underwater gripper based on a HASEL actuator.

[0008] Technical solution: The origami-type underwater gripper based on the HASEL driver described in the present invention includes a component sealing cabin, a driver group and a gripper, the gripper includes a connecting plate, a bending joint, a load-bearing frame and grasping fingertips, a plurality of load-bearing frames are connected through bending joints to form a gripper frame of a Z-shaped origami structure, and the angle of the bending joints is adjustable; the driver group includes a plurality of single drivers, the single drivers include a strain film and a powered electrode, the single drivers are connected through a folding film, and the driver group is folded at the folding film to form a Z-shaped origami structure; the driver groups are installed on both the inner and outer sides of the gripper frame of the gripper, and the strain film is located in the angle space formed by the load-bearing frame and the bending joint; when the outer driver group is started, the outer strain film expands, the angle on the outer side of the gripper frame becomes larger, the angle on the inner side becomes smaller, the gripper bends inward and enters a grasping state; similarly, when the inner driver group is started, the gripper bends outward and enters a released state.

[0009] Furthermore, the angle connection portion of the bending joint is an angle connection portion made of a flexible material.

[0010] Furthermore, the load-bearing frame is a load-bearing frame made of hard material.

[0011] Furthermore, the grasping fingertips are of a trapezoidal structure.

[0012] Furthermore, the outer side of the gripper is wrapped with a stretch-limiting skin.

[0013] Furthermore, the driver group is installed on the gripper frame by means of 3M glue, and a waterproof film is sealed on the surface of the driver group.

[0014] Furthermore, a boost circuit board is provided in the component sealed compartment, and the boost circuit board supplies power to the driver group through a waterproof plug.

[0015] Furthermore, after the inner and outer drivers are connected through wires, they are connected to the boost circuit board through a waterproof plug.

[0016] Furthermore, the number of grippers is not less than 2.

[0017] The parameter design method of the origami-type underwater gripper based on the HASEL actuator of the present invention comprises the following steps:

[0018] (1) Take the number of grippers as 3, and calculate the distribution circle diameter Da of the three grippers according to the diameter D of the object to be grasped;

[0019] (2) Calculate the length L of a single load-bearing frame based on the distribution circle diameter Da of the three grippers 骨 and width W 骨 ;

[0020] (3) According to the length L of a single load-bearing frame 骨 and width W 骨 Determine the length L of a single drive 驱 and width W 驱 ;

[0021] (4) According to the electrode length L corresponding to a single driver 电 and width W 宽 Calculate the liquid volume V in a single actuator;

[0022] (5) Calculate the grasping fingertip length L based on the length L of the grasped object 手 and the number of single drives N;

[0023] (6) Calculate the finger grasping force F

[0024]

[0025] Among them, ε r is the vacuum dielectric constant of the electrode; ε0 is the relative dielectric constant of the medium between the electrodes; U is the voltage value, and g is the gravitational acceleration;

[0026] (7) If but

[0027] Where, ΔL=0.2L 骨 ~0.3L 骨 ; ΔW=0.2W 骨 ~0.3W 骨 ; m is the mass of the grasped object; g is the acceleration due to gravity, and the process returns to step (3). Otherwise, the process continues;

[0028] (8) According to the formula Calculate the horizontal offset distance H when the finger is bent;

[0029] like Then D a Increase ΔD a , ΔD a 0.1Da ~0.2D a , until Otherwise it ends.

[0030] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: 1. The present invention designs the gripper frame and the driver group into a "Z" shape, and installs foldable driver groups on both the inner and outer sides of the gripper frame. When the driver group on one side is started, it will squeeze the driver group on the other side, so that the liquid in the driver returns to its initial state, overcoming the problem of slow driver recovery and improving the efficiency of grasping and releasing; at the same time, the gripper has two movement forms of opening inward and opening outward, thereby enhancing the grasping range; 2. The bending joint part responsible for bending in the present invention is made of flexible material, and the main body part responsible for bearing is a hard material structure, which overcomes the problem of insufficient bearing capacity of the soft gripper and maximizes the bearing capacity of the gripper without affecting the grasping range of the gripper. The fingers are wrapped with skin to reduce the influence of radial stretching on the bearing capacity; 3. The present invention estimates the volume and mass of the grasped object, reasonably designs the length, width and other parameters of important parts such as the skeleton and the driver group, and adjusts the distribution circle diameter and the driver size to make the grippers not interfere with each other when they reach the maximum bending angle, and maximize the grasping range of the grippers, which is targeted at the grasped objects and improves the versatility of the grippers. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of the present invention;

[0032] Figure 2 This is the main view of the component sealed cabin;

[0033] Figure 3 This is a top view of the sealed cabin for components;

[0034] Figure 4 It is a schematic diagram of the structure of the gripper skeleton;

[0035] Figure 5 It is a structural diagram of a single module of the gripper;

[0036] Figure 6 is a schematic diagram of the structure of the drive group in a folded state;

[0037] Figure 7 It is a schematic diagram of the structure of the driver group in the expanded state;

[0038] Figure 8 It is a folding schematic diagram of the drive group;

[0039] Fig. 9 This is the installation diagram of the driver;

[0040] Fig.10This is the schematic diagram of the deformation of the gripper skeleton;

[0041] Fig.11 Schematic diagram of gripping and releasing of the gripper;

[0042] Fig.12 The figure is a flow chart of the parameter design method of the present invention. DETAILED DESCRIPTION

[0043] The present invention will be further described below in conjunction with the accompanying drawings.

[0044] The origami-type underwater gripper based on the HASEL driver of the present invention comprises a component sealing cabin 1, a driver group 2, a gripper 3, and a stretch-limiting skin 4.

[0045] The component sealed chamber comprises a sealed chamber cover 12 , a sealed chamber body 11 , a boost circuit board 15 , a sealing ring 14 , and waterproof plugs 13 , 16 .

[0046] The sealed chamber body 11 is cylindrical in shape, with threaded holes distributed around the surface for installing the sealed chamber cover 12, and a concave surface and threaded holes are opened at the bottom according to the distribution circle size of three fingers to install the gripper 3. There are threaded holes inside for installing the copper column 17, and a through hole at the lower end for installing the waterproof plug 16.

[0047] The sealed bin cover 12 is in the shape of a disc, with a through hole at the top for installing a waterproof plug 13, and a circular groove at the bottom for installing a sealing ring 14. Through holes are distributed around it, corresponding to the threaded holes on the sealed bin body 11, and it is installed on the sealed bin body 11 with screws.

[0048] The boost circuit board 15 has through holes at four corners and is installed in the component sealed cabin 1 through copper pillars 17. The boost circuit board 15 has two circuits, which respectively control the driver group 2 on the inside and outside of the finger. The wires at the front end are welded to the waterproof plug 16 under the sealed cabin body 11 to energize the driver group 2, and the wires at the rear end are welded to the waterproof connector 13 on the sealed cabin cover 12 to energize the boost circuit board 15.

[0049] There are two sealing rings 14 in a circular shape and are installed in the grooves reserved in the sealing chamber cover 12.

[0050] There are two waterproof plugs 13 and 16, one is installed at the through hole above the sealed compartment cover 12, mainly used to connect an external power supply to power the boost circuit board 15. The other is installed at the through hole below the sealed compartment body 11, mainly used to connect the wires led out of the electrodes of the driver group 2, and connect the boost circuit board 15 with the driver group 2.

[0051] The gripper skeleton is in the shape of "Z" shaped origami. It consists of four structures, namely: a connecting plate 31, a bending joint 32, a load-bearing skeleton 33, and a grabbing fingertip 34. The connecting plate 31 cooperates with the concave surface reserved below the sealed warehouse body 11, and has a through hole corresponding to the threaded hole below the sealed warehouse body 11, and is installed below the sealed warehouse body with a hexagon socket screw. The bending joint 32 and the load-bearing skeleton 33 are composed of multiple "Z" shaped origami modules, and one bending joint 32 and two load-bearing skeletons 33 form a single module. The bending joint 32 is a joint position made of flexible material, and the load-bearing skeleton 33 is a main body made of hard material, corresponding to the folded drive group 2. The grabbing fingertip 34 is at the bottom of the skeleton, is trapezoidal, and is used to grab objects.

[0052] The driver group 2 is in the shape of a long strip when unfolded, and in the shape of a "Z"-shaped origami when folded. It includes: a strain film 21, a powered electrode 22, and a folded film 23. The strain film 21 is in the middle position, and is filled with liquid to expand after power is turned on. The powered electrode 22 is a graphite applied from top to bottom on the front and back sides of the driver. After power is turned on, the electrodes attract each other and squeeze the liquid to the strain film. The folded film 23 is a film with a certain distance between the two drivers, which is used for folding. The driver group 2 is folded into multiple "Z"-shaped origami structures as a whole, corresponding to the gripper frame, and is installed on the gripper frame with 3M glue. A layer of film is sealed on the surface of the driver group 2 for waterproofing. The internal and external drivers are divided into two groups, and the wires drawn out are welded together and connected to the waterproof plug 11.

[0053] The stretch limiting skin 4 is in the shape of a long strip and is made of silicone, which completely wraps the fingers of the gripper and is used for waterproofing and as a limiting layer.

[0054] like Fig.10 As shown in the figure, when the driver is powered on, the strained part expands and the frame is stretched. Fig.11 As shown in the figure, when the external drive group is started, the external frame angle becomes larger, the internal frame angle becomes smaller, the three fingers bend inward, and the gripper enters the grasping state; in order to quickly release the action, the internal drive group is started, the internal frame angle becomes smaller, the external frame angle becomes larger, the three fingers bend outward, and enter the release state. At the same time, the external drive is squeezed to restore it to its original state, which is convenient for the next grasping.

[0055] The parameter design method of the rigid-flexible coupling origami-type underwater gripper based on the HASEL actuator of the present invention comprises the following steps (all parameters are rounded up):

[0056] (1) Estimate the diameter of the object to be grasped to be D = 50 mm, its length to be L = 100 mm, and its mass to be M = 500 g.

[0057] (2) According to formula D a = kD (k = 1.4 ~ 1.5), the initial distribution circle diameter of the three grabs is D a =70mm.

[0058] (3) According to the formula Determine the length of the single module skeleton

[0059] L 骨 =44mm and width W 骨 =22mm.

[0060] (4) According to the formula L 驱 =L 骨 , W 驱 =W 骨 ; Determine the length L of a single drive 驱 =44mm and width

[0061] W 驱 =22mm.

[0062] (5) According to the formula W 电 =W 驱 ; Determine the length L of a single driver single electrode 电 =11mm and width W 电 =22mm.

[0063] (6) According to the formula The liquid volume within a single actuator was determined to be V = 3.4 ml.

[0064] (7) According to the length L and the formula (L 手 is the length of the fingertip), and the initial finger length L 手 =120mm and the number of folding modules N=30.

[0065] (8) According to the formula (where ε r is the dielectric constant of vacuum; ε0 is the relative dielectric constant of the medium between the electrodes; U is the voltage value), and the finger grasping force is obtained to be F=2.4N.

[0066] (9) Due to Then continue.

[0067] (10) According to the formula It is calculated that when the finger is bent, the horizontal offset distance is H = 45 mm.

[0068] because Then D a =D a +ΔDa (ΔD a =0.1D a ~0.2D a ) to loop and get the final D a =96mm.

Claims

1. An origami-type underwater gripper based on a HASEL actuator, characterized in that: The invention comprises a component sealed cabin (1), a driver group (2) and a gripper (3), wherein the gripper (3) comprises a connecting plate (31), a bending joint (32), a load-bearing frame (33) and a grasping fingertip (34), wherein a plurality of load-bearing frames (33) are connected via the bending joint (32) to form a gripper frame of a Z-shaped origami structure, wherein the angle of the bending joint (32) is adjustable; the driver group (2) comprises a plurality of single drivers, wherein the single drivers comprise a strain film (21) and a powered electrode (22), and the single drivers are connected via the folded film (23). Then, the driver group (2) is folded at the folding film (23) to form a Z-shaped origami structure; the driver groups (2) are installed on both the inner and outer sides of the gripper frame of the gripper (3), and the strain film (21) is located in the angle space formed by the load-bearing frame (33) and the bending joint (32); when the outer driver group is started, the outer strain film expands, the angle on the outer side of the gripper frame increases, and the angle on the inner side decreases, and the gripper bends inwards to enter a grasping state; similarly, when the inner driver group is started, the gripper bends outwards to enter a loosening state.

2. The origami-type underwater gripper based on the HASEL actuator according to claim 1, characterized in that: The angle connection portion of the bending joint is an angle connection portion made of a flexible material.

3. The origami-type underwater gripper based on the HASEL actuator according to claim 1, characterized in that: The load-bearing frame (33) is a load-bearing frame made of hard material.

4. The origami-type underwater gripper based on the HASEL actuator according to claim 1, characterized in that: The grasping fingertips (34) are of a trapezoidal structure.

5. The origami-type underwater gripper based on the HASEL actuator according to claim 1, characterized in that: The outer side of the gripper (3) is wrapped with a stretch-limiting skin (4).

6. The origami-type underwater gripper based on the HASEL actuator according to claim 1, characterized in that: The driver group (2) is mounted on the gripper frame by means of 3M glue, and a layer of waterproof film is then sealed on the surface of the driver group (2).

7. The origami-type underwater gripper based on the HASEL actuator according to claim 1, characterized in that: A boost circuit board (15) is arranged in the component sealed compartment (1), and the boost circuit board (15) supplies electricity to the driver group (2) through a waterproof plug (16).

8. The origami-type underwater gripper based on the HASEL actuator according to claim 7, characterized in that: After the inner and outer drivers are connected by wires, they are connected to the boost circuit board (15) via a waterproof plug.

9. The origami-type underwater gripper based on the HASEL actuator according to claim 1, characterized in that: The number of the grippers (3) is not less than 2.

10. A parameter design method for an origami-type underwater gripper based on a HASEL actuator as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: (1) Take the number of grippers as 3, and calculate the distribution circle diameter Da of the three grippers according to the diameter D of the object to be grasped; (2) Calculate the length L of a single load-bearing frame based on the distribution circle diameter Da of the three grippers 骨 and width W 骨 ; (3) According to the length L of a single load-bearing frame 骨 and width W 骨 Determine the length L of a single drive 驱 and width W 驱 ; (4) According to the electrode length L corresponding to a single driver 电 and width W 宽 Calculate the liquid volume V in a single actuator; (5) Calculate the grasping fingertip length L based on the length L of the grasped object 手 and the number of single drives N; (6) Calculate the finger grasping force F Among them, ε r is the vacuum dielectric constant of the electrode; ε0 is the relative dielectric constant of the medium between the electrodes; U is the voltage value; (7) If but Where, ΔL=0.2L 骨 ~0.3L 骨 ; ΔW=0.2W 骨 ~0.3W 骨 ; m is the mass of the grasped object; g is the acceleration due to gravity, and the process returns to step (3). Otherwise, the process continues; (8) According to the formula Calculate the horizontal offset distance H when the finger is bent; like Then D a Increase ΔD a , ΔD a 0.1D a ~0.2D a , until Otherwise it ends.

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