A foldable underwater gripper based on HASEL actuator and parameter design method

Abstract

The application discloses a kind of paper folding type underwater gripper based on HASEL driver and parameter design method, the paper folding type underwater gripper includes driver group and gripper, gripper includes connecting plate, curved joint, load skeleton and gripping fingertip, load skeleton is connected by curved joint and forms Z-shaped gripper skeleton, the included angle of curved joint can be adjusted;Driver group includes several single drivers, single driver includes strain film and electrified electrode, single driver is connected by folding film between, driver group is folded at folding film, and Z-shaped paper folding structure is formed;The inside and outside of the gripper skeleton of gripper are all installed driver group, and strain film is located in the included angle space formed by load skeleton and curved joint;When the driver group of outside is started, the strain film of outside expands, the included angle of the outside of gripper skeleton becomes larger, gripper bends inward, and enters gripping state;Reasonably, when the driver group of inside is started, gripper bends outward, and enters loose state.

Description

Technical Field

[0001] This invention relates to the field of soft robots, and more particularly to an origami-type underwater gripper based on a HASEL actuator and a parameter design method thereon. Background Technology

[0002] With the increasing demand for underwater operations, underwater robots and gripping devices are being used more frequently in fields such as marine exploration, deep-sea exploration, and seabed restoration. Traditional underwater grippers mostly rely on hydraulic or electric drives. While they possess strong gripping capabilities and adaptability, these systems typically suffer from drawbacks such as large size, high energy consumption, and complex structures. In the deep-sea environment, traditional systems often face limitations in size, difficulties in energy transmission, and insufficient operational precision.

[0003] In recent years, origami technology has been increasingly applied to the design of soft robots and underwater grasping devices due to its simple structure, lightweight design, and efficient space utilization. Origami-like structures can maintain lightness while possessing high rigidity and deformability, making them particularly suitable for delicate grasping tasks in complex underwater environments. Meanwhile, Hasel actuators, as a novel intelligent drive technology, achieve efficient motion actuation through the deformation of electrically controlled materials, exhibiting high energy 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 flexible fingers. The finger winding mechanism is mounted on the gripper fixing platform, and the flexible fingers are mounted on the finger winding mechanism. The finger winding mechanism can adjust the length of the flexible fingers. This allows for flexible adjustment of the finger length according to the size of the object being gripped, achieving the optimal gripping posture. However, using a soft cavity as the gripping force point results in poor load capacity. The gripping and releasing process requires waiting for the medium to change within the cavity, leading to slow speed and high requirements for power source control.

[0005] The paper "A Soft, Fast and Versatile Electrohydraulic Gripper with Capacitive Object Size Detection" proposes a self-sensing electrohydraulic bending gripper driven by a HASEL actuator, featuring capacitance pickup verification and object size detection. This gripper is fast, consumes low power, and can pick up a wide variety of objects through simple binary electrical control. However, when releasing an object, the actuator cannot immediately return to its initial state, resulting in a prolonged release time and affecting the gripping range for subsequent attempts.

[0006] Soft grippers typically use soft chambers for support, which results in insufficient gripping force. Traditional pneumatic and hydraulic grippers require the medium to fill before they can grip, resulting in a slow response time. Grippers using HASEL actuators generally suffer from slow actuator recovery speeds, leading to longer release times and thus affecting 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 HASEL actuators of this invention includes a component sealed chamber, an actuator assembly, and a gripper. The gripper includes a connecting plate, a bending joint, a support frame, and gripping fingertips. Several support frames are connected by bending joints to form a Z-shaped origami-like gripper frame, and the included angle of the bending joints is adjustable. The actuator assembly includes several individual actuators, each including a strain film and an energized electrode. The individual actuators are connected by folded films, and the actuator assembly is folded at the folded films to form a Z-shaped origami structure. The actuator assembly is installed on both the inner and outer sides of the gripper frame, and the strain film is located within the included angle space formed by the support frame and the bending joint. When the outer actuator assembly is activated, the outer strain film expands, the included angle on the outer side of the gripper frame increases, and the included angle on the inner side decreases, causing the gripper to bend inward and enter the gripping state. Similarly, when the inner actuator assembly is activated, the gripper bends outward and enters the releasing state.

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

[0010] Furthermore, the load-bearing skeleton is made of rigid material.

[0011] Furthermore, the grasping fingertip has a trapezoidal structure.

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

[0013] Furthermore, the actuator assembly is mounted on the gripper frame using 3M adhesive, and the surface of the actuator assembly is then sealed with a waterproof film.

[0014] Furthermore, a boost circuit board is installed inside the component sealed chamber, which powers the driver assembly through a waterproof connector.

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

[0016] Furthermore, there should be no fewer than two grips.

[0017] The parameter design method for the origami-type underwater gripper based on the HASEL actuator described in this invention includes 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 being gripped;

[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) Based on the length L of a single load-bearing frame 骨 and width W 骨 Determine the length L of a single driver 驱 and width W 驱 ;

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

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

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

[0024]

[0025] Where, ε r ε0 is the vacuum permittivity of the electrodes; ε0 is the relative permittivity 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 object being grabbed; g is the acceleration due to gravity, and return to step (3) or continue if the conditions are not met.

[0028] (8) According to the formula The horizontal offset distance H when the finger is bent is calculated.

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

[0030] Beneficial effects: Compared with the prior art, the significant advantages of this invention are: 1. This invention designs the gripper frame and actuator assembly in a "Z" shape, and installs folding actuator assemblies on both the inner and outer sides of the gripper frame. When one actuator assembly is activated, it will squeeze the other actuator assembly, causing the liquid inside the actuator to return to its initial state, overcoming the problem of slow actuator recovery and improving the efficiency of gripping and releasing; at the same time, it gives the gripper two movement forms: inward opening and outward opening, enhancing the gripping range; 2. In this invention, the bending joint part responsible for bending is made of flexible material, while the main body responsible for bearing is made of rigid material, overcoming the problem of insufficient load-bearing capacity of soft grippers, so that the gripper can maximize its load-bearing capacity without affecting its gripping range. The fingers are wrapped with skin to reduce the impact of radial tension on the load-bearing capacity; 3. This invention estimates the volume and mass of the object being grasped, and rationally designs the length, width and other parameters of important parts such as the skeleton and driver assembly. By adjusting the diameter of the distribution circle and the size of the driver, the grippers do not interfere with each other when they reach the maximum bending angle, and the gripping range of the grippers is maximized, making them more targeted to the objects being grasped and improving the versatility of the grippers. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the present invention;

[0032] Figure 2 This is a front view of the component sealing chamber;

[0033] Figure 3 A top view of the component sealing chamber;

[0034] Figure 4 This is a schematic diagram of the gripper frame.

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

[0036] Figure 6 A schematic diagram of the actuator assembly in its folded state;

[0037] Figure 7 This is a schematic diagram of the structure of the deployed state driver group;

[0038] Figure 8 A schematic diagram of the folding of the driver assembly;

[0039] Figure 9 This is a diagram illustrating the installation of the driver;

[0040] Figure 10A schematic diagram illustrating the deformation principle of the gripper frame;

[0041] Figure 11 A diagram illustrating the gripper's grasping and releasing action;

[0042] Figure 12 This is a flowchart of the parameter design method of the present invention. Detailed Implementation

[0043] The invention will now be further described with reference to the accompanying drawings.

[0044] The origami-type underwater gripper based on HASEL actuator of the present invention includes a component sealing chamber 1, a actuator group 2, a gripper 3, and a tension limiting skin 4.

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

[0046] The sealed chamber 11 is cylindrical in shape, with threaded holes distributed around its surface for installing the sealed chamber cover 12. A concave surface and threaded holes, shaped like the distribution of three fingers, are formed at the bottom for installing the gripper 3. Threaded holes are formed inside for installing the copper pillar 17, and a through hole is formed at the lower end for installing the waterproof plug 16.

[0047] The sealing chamber cover 12 is disc-shaped, 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 the perimeter, corresponding to the threaded holes on the sealing chamber body 11, and it is installed on the sealing chamber body 11 with screws.

[0048] The boost circuit board 15 has through holes at its four corners and is mounted inside the component sealing chamber 1 via copper pillars 17. The boost circuit board 15 has two lines that control the driver groups 2 on the inside and outside of the fingers, respectively. The wire at the front end is soldered to the waterproof plug 16 below the sealing chamber 11 to power the driver groups 2, and the wire at the rear end is soldered to the waterproof connector 13 on the sealing chamber cover 12 to power the boost circuit board 15.

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

[0050] There are two waterproof plugs, 13 and 16. One is installed in the through hole above the sealed chamber cover 12, mainly used to connect an external power supply to power the boost circuit board 15. The other is installed in the through hole below the sealed chamber body 11, mainly used to connect the wires leading out from the electrode of the driver group 2, connecting the boost circuit board 15 and the driver group 2.

[0051] The gripper skeleton is shaped like a "Z" origami. It consists of four structures: a connecting plate 31, a bending joint 32, a support frame 33, and gripping fingertips 34. The connecting plate 31 mates with a pre-drilled concave surface below the sealed chamber 11 and has through holes corresponding to threaded holes below the sealed chamber 11. It is installed below the sealed chamber using hexagonal screws. The bending joint 32 and the support frame 33 are composed of multiple "Z" origami modules, with one bending joint 32 and two support frames 33 forming a single module. The bending joint 32 uses flexible material at the joint position, while the support frame 33 uses rigid material for its main body, corresponding to the folding actuator assembly 2. The gripping fingertips 34, located at the bottom of the skeleton, are trapezoidal and used to grip objects.

[0052] The actuator assembly 2 unfolds into a long strip shape and folds into a "Z"-shaped origami form. It includes: a strain gauge 21, energized electrodes 22, and a folded film 23. The strain gauge 21 is located in the center and expands when energized, filled with liquid. The energized electrodes 22 are formed by coating graphite from top to bottom on both sides of the actuator; when energized, the electrodes attract each other, forcing the liquid to the strain gauge. The folded film 23 is a film with a certain distance between the two actuators, used for folding. The actuator assembly 2 is folded into multiple "Z"-shaped origami structures, corresponding to the gripper frame, and mounted on the gripper frame using 3M adhesive. A further film is applied to the surface of the actuator assembly 2 for waterproofing. The inner and outer actuators are divided into two groups, with their wires soldered together and connected to the waterproof plug 11.

[0053] The stretch-restricting skin 4, in the form of a long strip, is made of silicone and completely wraps around the gripper fingers. It serves as waterproofing and a restraining layer.

[0054] like Figure 10 As shown, when the driver is powered on, the strained parts expand, causing the frame to open. Figure 11 As shown, when the external actuator group is activated, the angle of the external skeleton increases, the angle of the internal skeleton decreases, and the three fingers bend inward, putting the gripper into a gripping state. To quickly release the gripper, the internal actuator group is activated, the angle of the internal skeleton decreases, the angle of the external skeleton increases, and the three fingers bend outward, putting the gripper into a releasing state. Simultaneously, the external actuator is compressed, returning it to its original state for easier gripping the next time.

[0055] The parameter design method for a rigid-flexible coupling origami-type underwater gripper based on a HASEL actuator, as described in this invention, includes the following steps (all parameters are rounded up):

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

[0057] (2) According to formula D a =kD (k = 1.4~1.5), the initial diameter of the distribution circle of the three claws is determined to be 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 formula L 驱 =L 骨 W 驱 =W 骨 Determine the length L of a single driver. 驱 =44mm and width

[0061] W 驱 =22mm.

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

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

[0064] (7) Based on length L and formula (L 手 To determine the fingertip length, the initial finger length L is set. 手 =120mm and the number of folding modules N=30.

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

[0066] (9) Due to Then continue.

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

[0068] because Then D a =D a +ΔDa (ΔD a =0.1D a ~0.2D a Repeat this process to obtain the final D. a =96mm.

Claims

1. A parameter design method for an origami-type underwater gripper based on a HASEL actuator, characterized in that, The origami-type underwater gripper based on HASEL actuators includes a component sealed chamber (1), an actuator assembly (2), and a gripper (3). The gripper (3) includes a connecting plate (31), a bending joint (32), a support frame (33), and gripping fingertips (34). Several support frames (33) are connected by bending joints (32) to form a gripper frame with a Z-shaped origami structure. The included angle of the bending joints (32) is adjustable. The actuator assembly (2) includes several individual actuators. Each individual actuator includes a strain film (21) and an electrode (22). The individual actuators are connected to each other. The actuator assembly (2) is folded at the folding film (23) to form a Z-shaped origami structure. The actuator assembly (2) is installed on both the inner and outer sides of the gripper frame of the gripper (3). The strain film (21) is located in the angle space formed by the supporting frame (33) and the bending joint (32). When the outer actuator assembly is activated, the strain film on the outer side expands, the angle on the outer side of the gripper frame increases, the angle on the inner side decreases, and the gripper bends inward to enter the gripping state. Similarly, when the inner actuator assembly is activated, the gripper bends outward to enter the releasing state. The parameter design method includes the following steps: (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 being gripped; (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) Based on the length L of a single load-bearing frame 骨 and width W 骨 Determine the length L of a single driver 驱 and width W 驱 ; (4) Based on the electrode length L corresponding to a single driver 电 and width W 宽 Calculate the liquid volume V within a single actuator; (5) Calculate the length of the grasping fingertip based on the length L of the object being grasped. and single drive number ; (6) Calculate finger grasping force ， in, The vacuum dielectric constant of the electrode; The relative permittivity of the medium between the electrodes; This is the voltage value; (7) If ,but in, ; m is the mass of the object being grabbed; g is the gravitational acceleration, and return to step (3) or continue if the other conditions are not met. (8) According to the formula The horizontal offset distance when the finger is bent is calculated as follows: ; like ,but Increase , for ~ until Conversely, the process ends if the condition is reversed.

2. The parameter design method for the origami-type underwater gripper based on the HASEL actuator according to claim 1, characterized in that, The angled connection of the bending joint is made of a flexible material.

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

4. The parameter design method for the origami-type underwater gripper based on a HASEL actuator according to claim 1, characterized in that, The grasping fingertip (34) has a trapezoidal structure.

5. The parameter design method for the origami-type underwater gripper based on the HASEL actuator according to claim 1, characterized in that, The gripper (3) is wrapped with a stretch-limiting skin (4) on the outside.

6. The parameter design method for the origami-type underwater gripper based on a HASEL actuator according to claim 1, characterized in that, The actuator assembly (2) is mounted on the gripper frame with 3M adhesive, and the surface of the actuator assembly (2) is then sealed with a waterproof film.

7. The parameter design method for the origami-type underwater gripper based on a HASEL actuator according to claim 1, characterized in that, The component sealed chamber (1) is equipped with a boost circuit board (15), which powers the driver assembly (2) through a waterproof plug (16).

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

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