Bionic soft gripper and control method thereof

Abstract

The invention discloses a bionic soft gripper and a control method thereof.The soft gripper adopts an electrostatic hydraulic amplification driver (HASEL), and the electrostatic hydraulic amplification driver on the outer side of a swinging soft layer of a soft gripping finger is used for enabling the whole bionic soft gripper to rotate in situ to find a gripping angle corresponding to a target through continuous multiple times of power-on expansion and power-off; the soft grabbing finger pitch changing mechanism is used for expanding the inner side space of the grabber for grabbing an object; the inner side continuous folding type electrostatic hydraulic amplification drivers of the soft grabbing fingers are used for enabling the soft grabbing fingers to be bent and opened towards the outer side, so that the grabbing space in the grabbing hand is maximized. The outer side continuous folding type electrostatic hydraulic amplification driver of the soft grabbing finger is used for enabling the soft grabbing finger to bend inwards to grab a to-be-grabbed target. The bionic gripper meets the special requirements of current scientific research and life use, and solves the problems that an existing bionic gripper is difficult to accurately control, easy to damage, leak electricity and liquid, difficult to grab irregular objects and single in working mode.

Description

Technical Field

[0001] This invention relates to the field of soft robot technology, and in particular to a biomimetic soft gripper and its control method. Background Technology

[0002] Traditional marine exploration primarily utilizes mechanical grippers driven by rigid components such as motors and gears. While these grippers offer precise control and high output force, they suffer from drawbacks including bulkiness, poor flexibility, limited adaptability to fragile or irregularly shaped objects, unsafe human-robot interaction, and limited operational modes. To achieve harmonious coexistence between humans and nature, and to avoid damaging the natural environment and ecosystem, there is an urgent need to develop robots capable of silently entering and grasping underwater objects, especially those with flexible actuation mechanisms.

[0003] Patent CN202511133329.X discloses an electrostatic hydraulically driven torsion module, robotic arm, and robotic hand. The torsion module body is driven by electrostatic hydraulics for torsion. The flexible material is lightweight, and the torsion mechanism is also flexible, reducing disturbance to marine life and resulting in a low failure rate. The filled oil is incompressible, enabling self-balancing of internal and external pressures underwater. However, its elephant-trunk-shaped extension module is relatively long and difficult to achieve multi-degree-of-freedom movement and precise control.

[0004] Patent CN202411366173.5 discloses a gripper and its control method for a flexible electrostatic hydraulic amplifier (HASEL) actuator. It mainly achieves bending direction control by setting a force-current coupling structure, and also incorporates a flexible electrostatic adsorption reinforcement layer and a gecko-like adsorption reinforcement layer to improve gripping stability. However, its connection and support method is unstable, has insufficient load-bearing capacity, and directly contacting the actuator's sealed bag with the grasped object can easily cause the BOPP plastic film to puncture, resulting in leakage and electrical leakage.

[0005] Patent CN202510229001.1 discloses a soft variable stiffness gripper based on a type electro-hydraulic amplification (HASEL) actuator. This invention achieves drive through the electro-hydraulic drive principle and uses the electrostatic adsorption layer interference principle to achieve variable stiffness. It has the characteristics of low energy consumption, fast response and high stiffness, and it is easy to achieve stable gripping and carrying capacity of the gripper. However, this gripper uses a flexible actuator to drive a rigid support plate to work, and the gripping working mode is single, which is not conducive to working in complex environments, and it is difficult to achieve gripping of irregularly shaped objects. Summary of the Invention

[0006] Purpose of the invention: The purpose of this invention is to provide a bionic soft gripper for precisely controlling the grasping of irregular objects; another purpose of this invention is to provide a control method for the bionic soft gripper.

[0007] Technical Solution: The bionic soft gripper of this invention includes soft gripping fingers, a soft gripper rotation mechanism, and a soft gripping finger pitch-changing mechanism. The soft gripping fingers include a fishbone-shaped soft skeleton, a swinging soft layer, a fixed layer, an inner continuously folded electrostatic hydraulic amplifier actuator, and an outer continuously folded electrostatic hydraulic amplifier actuator. The swinging soft layer is located on the left and right sides of the fixed layer, perpendicular to the directions of the inner and outer continuously folded electrostatic hydraulic amplifier actuators. The soft gripper rotation mechanism includes an electrostatic hydraulic amplifier actuator located on the outer side of the swinging soft layer. The soft gripping finger pitch-changing mechanism includes a horizontal telescopic actuator. The system includes linear guide rails and guide rail sliders; a fixed layer for the soft grasping fingers is slidably mounted on the linear guide rails of the body grasping finger pitch-changing mechanism via sliders; an electrostatic hydraulic amplification actuator located on the outside of the swinging soft layer is used to make the bionic soft grasper rotate in place to find the grasping angle corresponding to the target by continuously expanding and de-energizing; an inner continuously folding electrostatic hydraulic amplification actuator is used to make the soft grasping fingers bend and open outwards, maximizing the grasping space inside the grasper; an outer continuously folding electrostatic hydraulic amplification actuator is used to make the soft grasping fingers bend inwards to grasp the target to be grasped; and the body grasping finger pitch-changing mechanism is used to expand the inner space of the grasper grasping the object.

[0008] Furthermore, the fishbone-shaped soft skeleton has continuous fishbone-shaped skeletal grooves on both the inner and outer sides of the soft grasping finger mounting position. The skeletal grooves are rectangular and asymmetrically distributed on the inner and outer sides. The inner skeletal surface of the fishbone-shaped soft skeleton is a vertical plane, and the outer skeletal surface is an arch shape.

[0009] Furthermore, the fishbone-shaped soft skeleton, the swinging soft layer, and the fixing layer are integrally printed by a 3D printer. The fishbone-shaped soft skeleton and the swinging soft layer are printed with 3D printing soft material, while the fixing layer is printed with 3D printing hard material.

[0010] Furthermore, the horizontal telescopic actuator includes a Z-shaped continuous electrostatic hydraulic amplification actuator and a side plate. The horizontal telescopic actuator is connected to the inner side of the fixing layer for the soft gripping finger and the outer vertical plate of the guide rail fixing plate.

[0011] Furthermore, the sealing bags of the inner continuously folded electro-hydraulic amplifier actuator, the outer continuously folded electro-hydraulic amplifier actuator, the electro-hydraulic amplifier actuator located on the outside of the swinging soft layer, and the Z-shaped continuous electro-hydraulic amplifier actuator are all made of TPU high-transparency polyurethane film.

[0012] Furthermore, the bionic soft gripper also includes a soft silicone waterproof sealant, an underwater detection camera, and a component control cabin.

[0013] Furthermore, the underwater detection camera is a high-definition waterproof and visual underwater camera with a 360° wide-angle lens and a built-in depth sensor.

[0014] Furthermore, the underwater detection camera is installed in the central circular hole area of ​​the soft silicone waterproof sealant and is connected to the soft silicone waterproof sealant by waterproof adhesive. The cable passes through the central circular hole of the soft gripping finger pitch-changing mechanism and is connected to the component control compartment.

[0015] Furthermore, the component control compartment includes a communication interface, Raspberry Pi, expansion board, relay, serial port regulator, boost module, wiring serial port, and terminal blocks.

[0016] The biomimetic soft gripper and its control method described in this invention include the following steps:

[0017] (1) The mother ship carrying the bionic soft gripper moves to the target to be grabbed. The mother ship lowers the bionic soft gripper to the target by the winch. The depth of the bionic soft gripper in the water is recorded as H.

[0018] (2) Control the underwater detection camera under the bionic soft gripper to capture underwater images and upload them to the host computer. Establish the distortion correction function of the wide-angle camera through the position of each marker point and perform distortion correction processing on the captured images.

[0019] (3) Based on the preset marker points on the soft grasping finger and the pixel points of the target to be grasped, the distance from the marker points on the soft grasping finger to the target to be grasped in the image is determined by the reference object method after measurement and distortion processing. The actual height difference between the bionic soft grasping finger and the target to be grasped is converted by the similar triangle method.

[0020] (4) Determine whether the actual height difference between the bionic soft gripper and the target to be grasped is greater than the height difference threshold. If the height difference is greater than Then control the mother ship to rotate the winch to continue lowering the bionic soft gripper; if the height difference is no greater than Proceed to step (5);

[0021] (5) The host computer controls the underwater detection camera to capture underwater images. By capturing the images and the various markers of the soft grasping fingers, the horizontal distance parameters between the bionic soft grasper and the target to be grasped are obtained. The soft grasping finger closest to the target to be grasped is determined. The soft grasping finger works to make the bionic soft grasper swim to the top of the target to be grasped.

[0022] (6) If the horizontal distance between the bionic soft gripper and the target to be grasped is within the horizontal distance threshold of the target to be grasped. If the distance is within the specified range, proceed to step (7); otherwise, repeat step (5) until the horizontal distance between the bionic soft gripper and the target being grasped is within the horizontal distance threshold. Inside;

[0023] (7) Stop the movement of the bionic soft gripper. The electrostatic hydraulic amplifier driver located on the outside of the swinging soft layer expands and de-energizes the bionic soft gripper in place by repeatedly turning it on and off, so that the bionic soft gripper rotates in place to find the gripping angle corresponding to the target and then stops rotating.

[0024] (8) The Z-shaped continuous electrostatic hydraulic amplifier of the horizontal telescopic actuator in the four directions of the horizontal telescopic actuator is simultaneously energized and expanded, driving the guide rail slider and soft gripping finger connected to the horizontal telescopic actuator to move outward to the maximum position at the same time, expanding the inner space of the gripper to grasp the object.

[0025] (9) After the finger pitch is changed, the inner continuous folding electrostatic hydraulic amplifier driver is simultaneously energized and expanded, and the grasping fingers bend and open outward to maximize the grasping space inside the gripper.

[0026] (10) The mother ship rotates the winch to continue lowering the bionic soft gripper to the bottom. The inner continuous folding electrostatic hydraulic amplifier driver is de-energized, and the soft gripping finger returns to its original shape. At the same time, the outer continuous folding electrostatic hydraulic amplifier driver is energized and expands, and the soft gripping finger bends inward to grasp the target to be grasped.

[0027] Furthermore, in step (5), after determining the soft grasping finger that is more inclined towards the target to be grasped, the soft grasping finger works to move the bionic soft grasper to directly above the target to be grasped, as follows:

[0028] (51) The electrostatic hydraulic amplifier driver on the same side of the soft layer controls the swing of all soft gripping fingers, continuously energizing and de-energizing to cause the gripper to rotate in place, so that the soft gripping finger closest to the target rotates to an angle with the target at the angle threshold. Within the range;

[0029] (52) Control the continuous folding electrostatic hydraulic amplifier driver on the inner side of the soft grasping finger to continuously energize and de-energize, so that the bionic soft grasping hand moves to the direction of the target to be grasped and directly above the target.

[0030] The working principle of this invention is as follows:

[0031] Utilizing the driving principle of a HASEL (Hydraulic Electrostatic Amplification) actuator, this actuator heat-seals flexible TPU plastic film and liquid dielectric into sealed bags of various shapes. When applied and energized, these bags expand and deform, generating a driving effect. This allows for efficient stretching, bending, and horizontal movement of the carrier. The TPU plastic film exhibits excellent flexibility and toughness, exhibiting large deformation without significant damage. A high-dielectric-constant dielectric liquid is selected as the medium for electrostatic amplification and conversion. This not only effectively enhances the electrostatic discharge between electrodes but also, due to its excellent fluidity, effectively compensates for dielectric loss after electrical breakdown, allowing the material to immediately return to its insulating state and achieve instant self-healing. Furthermore, combining a continuously folding HASEL actuator with soft fingers, the expansion and subsequent restoration of the gripper's original shape after energization underwater produces a tactile effect. Repeated energization and de-energization of a single soft grasping finger, causing the inner and outer actuators to expand and then restore their original shape, creates a swimming effect towards that finger underwater. Four soft grasping fingers arranged in a circle, moving in one direction through repeated energization, enable the gripper to swim and rotate in place underwater.

[0032] Beneficial Effects: Compared with existing technologies, the significant advantages of this invention are: 1. The bionic soft gripper provided by this invention uses a multi-segment parallel continuous electrostatic hydraulic amplification actuator to achieve various complex working modes. Combining the multi-segment parallel continuous electrostatic hydraulic amplification actuator with a linear guide rail enables horizontal movement of the gripping fingers, changing the gripping range and adapting to underwater objects of different sizes. 2. This invention uses a TPU high-transparency polyurethane film. Compared with traditional BOPP or PET films, TPU film has better flexibility and toughness, greater deformation, and is less prone to damage. After power failure, there is almost no residual current, and the self-repair speed is faster. 3. The gripping fingers of this invention adopt a 3D-printed pure soft structure and a staggered fishbone structure, which can adapt to various shapes of objects and has stronger environmental adaptability. The opposite side of the gripper is designed with one flat side and one curved side to adapt to water flow. Combining two sets of parallel continuous electrostatic hydraulic amplification actuators placed in the skeleton notch allows all four fingers to work simultaneously, with the inner side driving the opening of the fingers and the outer side driving the gripping. Controlling the inner actuator of a single finger to repeatedly turn the power on and off allows the entire gripper to move to one side, enabling movement in four underwater directions. Furthermore, placing two sets of electrostatic hydraulic amplification actuators on the left and right sides of the gripper, combined with the swinging soft layer, allows controlling each finger's actuator to repeatedly turn the power on and off to the same side, enabling the entire gripper to rotate in place. 4. The underwater object-grabbing control method of the bionic soft gripper with electrostatic hydraulic amplification actuators provided by this invention uses a wide-angle camera to calculate and capture the target, allowing the gripper to move more precisely to the underwater target location for accurate object grabbing. Moreover, by employing a series of steps including rotation, pitch adjustment, opening, and grabbing, it can be applied to grabbing various complex environments and irregular objects. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the present invention;

[0034] Figure 2 A schematic diagram of the structure for software to grasp a finger;

[0035] Figure 3 This is a schematic diagram of the installation of the swinging soft layer;

[0036] Figure 4 A diagram showing the left and right swinging motion of a single finger;

[0037] Figure 5 A diagram showing the left and right swinging and rotating motions of all fingers in place;

[0038] Figure 6 A schematic diagram of a variable-pitch mechanism for software-grabbing fingers;

[0039] Figure 7 This is a schematic diagram of the electrostatic hydraulic amplifier HASEL driver structure.

[0040] Figure 8 A schematic diagram of the expansion and deformation of the electrostatic hydraulic amplifier HASEL driver during operation;

[0041] Figure 9 A schematic diagram of the variable-pitch mechanism for software-grabbing fingers before the variable-pitch operation;

[0042] Figure 10 This is a schematic diagram of the variable-pitch mechanism for software finger grasping after the pitch has been changed.

[0043] Figure 11 A diagram illustrating how a gripper software can grasp open fingers;

[0044] Figure 12 A diagram illustrating the gripping state of a gripper software where the fingers are bent inwards.

[0045] Figure 13 A schematic diagram illustrating how a gripper software can grasp an object by bending its fingers inward.

[0046] Figure 14 A schematic diagram of the structure for securing the outer casing to the gripper;

[0047] Figure 15 A schematic diagram showing how the gripper secures the upper compartment of the outer shell;

[0048] Figure 16 A schematic diagram showing how the gripper secures the lower compartment of the outer shell;

[0049] Figure 17 This is a flowchart of the method of the present invention. Detailed Implementation

[0050] like Figure 1As shown, the bionic soft gripper based on an electrostatic hydraulic amplification (HASEL) actuator of the present invention includes a soft gripping finger 1, a soft gripper rotation mechanism 2, a soft gripping finger pitch-changing mechanism 3, a gripper fixing shell 4, a soft silicone waterproof seal 5, and an underwater detection camera 6. The underwater detection camera is a high-definition waterproof and visual underwater camera with a 360° wide-angle lens and a built-in depth sensor. It is installed in the central circular hole area of ​​the soft silicone waterproof seal and connected to the seal via waterproof adhesive. A cable passes through the central circular hole of the soft gripping finger pitch-changing mechanism and connects to the component control compartment.

[0051] like Figure 2 and Figure 3As shown, the soft grasping finger 1 includes a fishbone-shaped soft skeleton 101, a swinging soft layer 102 that can swing left and right, a rigid fixing layer 103 in the middle, an inner continuously folded electro-hydraulic amplifier (HASEL) actuator 104, an outer continuously folded electro-hydraulic amplifier (HASEL) actuator 105, and a waterproof finger skin 106. The fishbone-shaped soft skeleton, the swinging soft layer, and the rigid fixing layer are all integrally printed using a multi-functional rigid-soft 3D printer. The fishbone-shaped soft skeleton and the swinging soft layer are made of 3D printed soft material, while the rigid fixing layer is made of 3D printed hard material. The fishbone-shaped soft skeleton is cuboid in shape, with continuous fishbone-shaped skeleton slots on both the inner and outer sides relative to the soft grasping finger's mounting position. These skeleton slots are rectangular and asymmetrically distributed on the inner and outer sides. The inner skeleton surface of the fishbone-shaped soft skeleton is a vertical plane, while the outer skeleton surface is an arc surface; the left side is a vertical plane, and the right side is an arc surface. The intermediate rigid fixing layer is T-shaped and located at the top center of the fishbone-shaped soft skeleton. It is integrally printed with the fishbone-shaped soft skeleton using a multi-functional rigid-soft 3D printer. The swinging soft layer consists of two cuboid shapes, symmetrically distributed on the left and right sides of the intermediate rigid fixing layer above the fishbone-shaped soft skeleton. It is also integrally printed with the fishbone-shaped soft skeleton using a multi-functional rigid-soft 3D printer. The inner continuously folded electrostatic hydraulic amplification (HASEL) driver 104 includes a continuous plastic film sealing bag, a liquid dielectric, and aluminum foil patch electrodes. The continuous plastic film sealing bag is formed by heat-sealing two pieces of TPU high-transparency polyurethane film into multiple rows of rectangular sealing bags using a 3D printer heating nozzle. Each rectangular sealing bag has an oil filling port. The liquid dielectric is filled through the notch using a syringe, and then the oil filling port is heat-sealed with a soldering iron. The aluminum foil electrodes are attached to the same side of the upper and lower surfaces of each sealing bag of the continuous plastic film sealing bag, with the electrode positions symmetrical. The externally continuous folding electrostatic hydraulic amplifier (HASEL) driver 105 includes a continuous arch-shaped plastic film sealing bag, a liquid dielectric, and an aluminum foil patch electrode. The continuous arch-shaped plastic film sealing bag is formed by sealing two pieces of TPU high-transparency polyurethane film through a 3D printer heating nozzle into a series of row-by-row arch-shaped sealing bags. The upper part is semi-circular and the lower part is rectangular. Each arch-shaped sealing bag has an oil filling port. The liquid dielectric is filled into the oil filling port with a syringe and then the oil filling port is heat-sealed with a soldering iron. The aluminum foil electrode is attached to the semi-circular part of the upper and lower surfaces of each sealing bag of the continuous arch-shaped plastic film sealing bag.

[0052] During the grasping task, the mothership equipped with the bionic soft gripper moves to above the target. The mothership lowers the bionic soft gripper above the target using a winch. The underwater detection camera 6 is activated and records the gripper's real-time depth. The underwater images captured by the wide-angle lens of the underwater detection camera 6 are uploaded to the host computer. A distortion correction function for the wide-angle camera is established based on the positions of various marker points, and the captured images are processed to correct distortion. By measuring the distances from the target to the marker points of the soft gripper in the distorted image, the actual height distance between the bionic soft gripper and the target is calculated. The height difference between the gripper and the target after lowering is within a threshold value. Within the range, once the bionic soft gripper reaches a suitable position at a distance from the target to be grasped, it stops.

[0053] When the bionic soft gripper reaches a suitable height, the host computer controls an underwater detection camera to capture underwater images. By analyzing the captured images and identifying markers on the soft gripping fingers, the horizontal distance between the gripper and the target is obtained. Next, based on the captured images, the computer determines which soft gripping finger is closer to the target. It then controls the actuators on the same side of the soft gripping layer of the four fingers to repeatedly energize and de-energize, causing the gripper to rotate in place. This rotates the soft gripping finger closest to the target until the angle between the finger and the target is within a threshold value. In the middle. Then, by controlling the continuous folding electrostatic hydraulic amplifier (HASEL) driver on the inner side of this soft grasping finger to continuously expand and de-energize, the bionic soft grasper moves towards the target to be grasped and directly above the target, so that the horizontal distance between the bionic soft grasper and the target is within a threshold ( Within the range of ).

[0054] The gripper's in-situ rotation mechanism includes two electro-hydraulic amplification (HASEL) actuators and a left-right swinging soft layer for the four soft gripping fingers, located at the uppermost region of the four soft gripping fingers. The two HASEL actuators are connected to the sides of the left-right swinging soft layer 102 via strong waterproof adhesive. Figure 4 As shown, the gripper rotation mechanism 2 consists of two electrostatic hydraulic amplifiers 201 attached to both sides of the soft layer 102 where the soft gripping fingers 102 swing left and right. After the bionic soft gripper reaches directly above the underwater target object, the host computer controls the gripper rotation mechanism 2 to operate, causing the electrostatic hydraulic amplifiers 201 on the same side of the soft layer 102 where the four soft gripping fingers 1 swing left and right to be energized and de-energized multiple times, resulting in a swimming effect of the bionic soft gripper rotating in place. Figure 5 As shown, after rotating in place to find a suitable gripping angle, the electrostatic hydraulic amplifier driver 201 on the four software gripping fingers 1 is de-energized to stop the rotation of the gripper.

[0055] like Figure 6 As shown, the soft-grip finger-grabbing mechanism 3 includes a horizontal telescopic driver 301, a linear guide rail 302, a guide rail slider 303, a guide rail base plate 304, and a limiting mechanism 305. There are two sets of soft-grip finger-grabbing mechanisms, each connecting two soft-grip fingers. The guide rail fixing plates of the two sets of mechanisms are placed perpendicularly to each other in a cross shape and connected by strong waterproof adhesive. The guide rail fixing plate includes a long base plate and four small vertical plates, both integrally printed by a 3D printer in a U-shape. Two small vertical plates are connected to the left and right sides of the long base plate perpendicular to it, and two small vertical plates are perpendicular to the long base plate in the middle, with a circular hole in the center. The long base plate is connected to the gripper housing by four screws. There are two sets of the linear guide rail slider mechanism, including a linear guide rail and a guide rail slider; one set is located on the left side of the guide rail base plate, and the other set is located on the right side. The linear guide rail is connected to the guide rail base plate by screws. Its left and right sides abut against two vertical plates on one side of the guide rail base plate. The guide rail slider is embedded in the linear guide rail, and the lower surface of the slider is connected to the upper middle rigid fixing layer of the soft grasping finger with adhesive. The horizontal telescopic actuator includes a Z-shaped continuous electrostatic hydraulic amplification (HASEL) actuator and two side plates. The two side plates are connected to the left and right sides of the Z-shaped continuous electrostatic hydraulic amplification (HASEL) actuator with strong waterproof adhesive. The entire assembly is connected to the inner side of the middle rigid fixing layer of the soft grasping finger and the outer vertical plate of the guide rail fixing plate with strong waterproof adhesive. There are two sets of horizontal telescopic actuators, located below the linear guide rail slider mechanism on the guide rail base plate. The Z-shaped continuous electrostatic hydraulic amplification (HASEL) actuator is heat-sealed from two layers of TPU high-transparency polyurethane film into multiple consecutive rectangular sealed bags with gaps between each pair. Each bag is filled with a liquid dielectric, and two aluminum foil electrodes are symmetrically attached to half of the upper and lower surfaces of each rectangular sealed bag. The side plate is made of 3D-printed rigid material and is rectangular in shape. The limiting mechanism includes a spring and two square plates, which are connected to the two ends of the spring with strong adhesive. The entire assembly is connected with strong adhesive to the outermost vertical plate of the guide rail fixing plate and the outer side of the middle rigid fixing layer for the soft gripping finger. The spring is a high-flexibility telescopic spring. The square plate is made of 3D-printed rigid material and is square in shape.

[0056] like Figure 7As shown, the 201 electrostatic hydraulic amplifier (HASEL) driver used in this invention includes an aluminum foil patch electrode 2011, a TPU high-transparency polyurethane film 2012, and a liquid dielectric vegetable transformer oil 2013. Two TPU films are heat-sealed 2012 into a rectangular plastic sealing bag using a heat-sealing machine. After the liquid dielectric vegetable transformer oil 2013 is injected, the opening is sealed with a soldering iron. Then, two aluminum foil patch electrodes 2011 are attached to both sides of the sealing bag. The plastic film sealing bag is rectangular in shape and consists of two TPU high-transparency polyurethane films. The thickness of the TPU film is preferably 0.1 mm. The TPU film is heat-sealed into a rectangular shape using a heat-sealing machine, leaving an oil injection port. The liquid dielectric is vegetable transformer oil, which is injected into the sealing bag through the oil injection port using a syringe. The oil injection port is then heat-sealed with a soldering iron. The aluminum foil patch electrode is a thin aluminum tape, preferably 0.1 mm thick, cut into two rectangular shapes with scissors. The aluminum foil patch electrodes are symmetrically attached to the upper and lower sides of the plastic sealing bag, and the area of ​​the aluminum foil patch electrode occupies half of the surface area of ​​the plastic film sealing bag.

[0057] like Figure 8 As shown, when the electrostatic hydraulic amplifier driver (HASEL) is powered on and the positive and negative terminals are energized and the voltage is amplified, the side of the plastic sealed bag with the aluminum foil patch electrode will be squeezed, squeezing the liquid dielectric to the other side of the area without the electrode, causing expansion and deformation to support the object.

[0058] After finding a suitable gripping angle, the host computer controls the simultaneous energization and expansion of the four horizontal telescopic actuators 301 of the soft gripping finger variable-pitch mechanism 3. This causes the Z-shaped continuous electrostatic hydraulic amplification (HASEL) actuators of the four horizontal telescopic actuators to expand simultaneously, driving the guide rail slider 303 connected to the horizontal telescopic actuator 301 and the soft gripping finger 1 to move outwards simultaneously, opening the four soft gripping fingers 1 and expanding the inner space of the gripper to grasp the object. Figure 9 As shown, this is the state before the software grasps finger 1 and changes its distance. Figure 10 The image shows that after the soft gripper finger 1 is opened with varying distance, the internal gripping space of the gripper becomes larger.

[0059] like Figure 11 As shown, after the soft grasping finger 1 completes the pitch change, the host computer controls the continuous folding electrostatic hydraulic amplifier (HASEL) driver 104 of the inner side of the four grasping fingers of the bionic soft grasper to expand simultaneously, so that the four soft grasping fingers 1 bend and open outward as a whole, thereby maximizing the grasping space inside the grasper.

[0060] like Figure 12As shown, the mother ship then rotates the winch to continue lowering the bionic soft gripper to the bottom. The host computer controls the power off of the inner continuous folding electrostatic hydraulic amplifier (HASEL) 104 driver of the four gripping fingers, so that the four soft gripping fingers 1 return to their original state. Then, the host computer controls the power on the outer continuous folding electrostatic hydraulic amplifier (HASEL) driver 105 of the four gripping fingers to expand, so that the four soft gripping fingers 1 bend inward to grasp the target 9 to be grasped.

[0061] like Figure 13 The diagram shown illustrates the bionic soft gripper grasping the target 9. Finally, the host computer controls the continuous folding electrostatic hydraulic amplifier (HASEL) actuators on the outer sides of the four gripping fingers to de-energize and restore them to their original state, thus lowering the target object and completing the underwater object grasping operation.

[0062] like Figure 14 , Figure 15 and Figure 16As shown, the gripper fixing housing includes an upper housing 401, a lower housing 402, an end cap 403, a waterproof connector 404, hex socket screws 405, a communication interface 4021, a Raspberry Pi 4022, an expansion board 4023, a relay 4024, a serial port regulator 4025, a boost module 4026, a serial port 4027, and terminal blocks 4028. The upper housing 401 and lower housing 402 are integrally printed using a 3D printer. The upper housing 401 is connected to the end cap by screws, and the waterproof connector is connected to the end cap by threads. The upper housing 401 includes a communication interface, a Raspberry Pi, an expansion board, a relay, a serial port regulator, a boost module, a serial port, and terminal blocks. It is cylindrical in shape with eight threaded holes around its perimeter and is connected to the end cap by screws. Each component is connected to the bottom of the component control compartment via waterproof adhesive. The lower compartment 402 of the gripper fixing shell is cylindrical in shape with a cross-shaped slot at the bottom. It is integrally connected to the upper component control compartment at the top. The gripping software finger pitch-changing mechanism is installed at the cross-shaped slot, and the lower compartment 402 of the gripper fixing shell is connected to the software gripping finger pitch-changing mechanism by screws. The end cap consists of an upper plate, a lower plate, and a support column, which are 3D printed as a whole, with a through threaded hole in the middle. The upper plate is circular with a threaded hole in the center, and the waterproof connector is connected to the center of the end cap through the threaded hole in the center of the end cap. The lower plate is circular with a threaded hole in the middle and eight small through holes around it, and is connected to the upper component control compartment by screws. The support column is cylindrical with a circular hole in the middle. The soft silicone waterproof seal is made of soft silicone skin, cut into a cross shape, with a circular hole in the middle and an avoidance opening on each of the four sides. The soft gripper finger passes through the avoidance opening. The soft silicone waterproof seal is stuck in the lower connection area of ​​the gripper finger pitch-changing mechanism. The soft silicone skin is connected to the bottom of the gripper fixing shell by waterproof adhesive, sealing the gap below.

[0063] like Figure 17 As shown, the bionic soft gripper and its control method of the present invention include the following steps:

[0064] Step 1: Conduct various checks before the entire system is launched into the water, including checking the host computer, circuitry, waterproofing layer, and wiring of the bionic soft gripper.

[0065] Step 2: Define the underwater depth of the bionic soft gripper as H, the underwater entry point as the origin (0, 0, 0), and the position of the target to be grasped as (x, y, z). Set two image markers on each of the four soft gripping fingers, with each marker equidistant from the others (P). Label the four soft gripping fingers 1, 2, 3, and 4. Define the angle threshold between the soft gripping fingers and the target to be grasped as... The height difference threshold between the bionic soft gripper and the target to be grasped is: The horizontal distance threshold from the target to be captured is ( ).

[0066] Step 3: Move the mother ship with the bionic soft gripper to above the target to be grabbed. The mother ship lowers the bionic soft gripper above the target using a winch. Record the depth of the bionic soft gripper in the water as H.

[0067] Step 4: Control the wide-angle lens of the underwater detection camera under the bionic soft gripper to capture underwater images and upload them to the host computer. Establish the distortion correction function of the wide-angle camera through the position of each marker point, and perform distortion correction processing on the captured images to straighten the originally curved lines of the images, so that the pixels in the images can be connected with the points in the coordinate system through standard perspective projection geometry.

[0068] Step 5: Record the two marker points on the soft grasping finger and the pixel points of the target to be grasped in the photo. Measure the distance from the two marker points on the soft grasping finger to the target in the image after distortion removal using the reference object method. Then, convert the actual height difference between the bionic soft grasper and the target to be grasped using the similar triangle method.

[0069] Step 6: Determine the height difference between the bionic soft gripper and the target to be grasped. If the height difference is greater than... Then, control the mother ship to rotate the winch and continue to lower the bionic soft gripper.

[0070] Step 7: Then return to step 4 to take a picture and detect if the height difference is within the threshold after placement. If, within the specified range, you reach a suitable position at a distance from the target to be grabbed, continue with the following steps. If the height difference is still greater than [a certain value], proceed to the next step. Then repeat step 6 until the height difference reaches the threshold.

[0071] Step 8: When the bionic soft gripper reaches a suitable height, the host computer controls the underwater detection camera to capture underwater images. By capturing the images and various marker points of the soft gripper's fingers, the horizontal distance parameters between the bionic soft gripper and the target to be grasped are obtained.

[0072] Step 9: Based on the captured images, determine which soft grasping finger of the bionic soft gripper is more similar to the target to be grasped, and then activate that soft finger to move the entire device directly above the target.

[0073] (91) The electrostatic hydraulic amplifier (HASEL) driver on the same side of the soft layer continuously energizes and de-energizes the four soft gripping fingers to control their left and right swings, causing the gripper to rotate in place and rotate the soft gripping fingers close to the target to the target until the angle between the gripping fingers and the target is within a threshold value. middle.

[0074] (92) Control the continuous folding electrostatic hydraulic amplifier (HASEL) driver on the inside of the soft grasping finger to continuously energize and de-energize, so that the bionic soft grasping hand moves to the direction of the target to be grasped and directly above the target.

[0075] Step 10: Return to step 8 for detection. If the horizontal distance between the bionic soft gripper and the target to be grasped is within the threshold ( If the horizontal distance is within the specified range, continue with the following steps. Then repeat step 9 until the horizontal distance difference reaches the threshold.

[0076] Step 11: After the bionic soft gripper reaches directly above the underwater target object, the continuous folding electrostatic hydraulic amplifier (HASEL) driver on the inside of the soft gripping finger is powered on to stop the gripper's movement.

[0077] Step 12: The host computer controls the four gripping fingers to swing left and right. The electrostatic hydraulic amplifier (HASEL) driver on the same side of the soft layer is continuously energized and de-energized multiple times, so that the gripper produces a swimming effect of rotating in place. The underwater detection camera captures the scene. After rotating in place to find a suitable gripping angle, the driver is turned off and the gripper is energized to stop the rotation.

[0078] Step 13: After finding a suitable gripping angle, the host computer controls the Z-shaped continuous electrostatic hydraulic amplifier (HASEL) driver of the horizontal telescopic driver of the gripping soft finger to expand simultaneously in all four directions. This causes the guide rail slider connected to the horizontal telescopic driver and the soft gripping finger to move outward to the maximum position at the same time. The four soft gripping fingers open horizontally in four directions, expanding the inner space of the gripper to grasp the object.

[0079] Step 14: After the finger pitch is adjusted, the host computer controls the continuous folding electrostatic hydraulic amplifier (HASEL) drivers on the inner sides of the four grasping fingers of the bionic soft gripper to expand simultaneously, causing the four grasping fingers to bend and open outward as a whole, thereby maximizing the grasping space inside the gripper.

[0080] Step 15: Let the mother ship rotate the winch to continue lowering the bionic soft gripper to the bottom. Control the power off of the continuous folding electro-hydraulic amplifier (HASEL) drivers on the inner side of the four gripping fingers, so that the four soft gripping fingers return to their original shape. Then control the power on the continuous folding electro-hydraulic amplifier (HASEL) drivers on the outer side of the four soft gripping fingers to expand, so that the four soft gripping fingers bend inward to grasp the target to be grasped.

[0081] Step 16: After the target is captured, the mother ship uses a winch to pull up the bionic soft gripper, bringing the underwater target object's bionic soft gripper out of the water and completing the gripper retrieval.

[0082] Step 17: The host computer controls the four gripping fingers to continuously fold the electrostatic hydraulic amplifier (HASEL) driver on the outside to power off and restore it to its original state, and put down the target object to complete the underwater object gripping work.

[0083] Step 18: If the underwater grabbing operation continues, repeat steps 3 through 17. If not, end the operation.

Claims

1. A biomimetic soft gripper, characterized in that, The system includes a soft gripper finger (1), a soft gripper rotation mechanism (2), and a soft gripper finger pitch-changing mechanism (3). The soft gripper finger (1) includes a fishbone-shaped soft skeleton, a swinging soft layer, a fixed layer, an inner continuously folding electrostatic hydraulic amplifier driver, and an outer continuously folding electrostatic hydraulic amplifier driver. The swinging soft layer is located on the left and right sides of the fixed layer, perpendicular to the directions of the inner continuously folding electrostatic hydraulic amplifier driver and the outer continuously folding electrostatic hydraulic amplifier driver. The soft gripper rotation mechanism (2) includes an electrostatic hydraulic amplifier driver (201) located on the outside of the swinging soft layer. The soft gripper finger pitch-changing mechanism (3) includes a horizontal telescopic driver (301) and a linear guide rail (302). The fixed layer of the soft grasping finger (1) is slidably mounted on the linear guide rail (302) of the body grasping finger pitch mechanism (3) by the slider; the electrostatic hydraulic amplifier driver (201) located on the outside of the swinging soft layer is used to make the bionic soft gripper rotate in place to find the grasping angle corresponding to the target by continuously expanding and de-energizing multiple times; the inner continuous folding electrostatic hydraulic amplifier driver is used to make the soft grasping finger bend and open outward, so as to maximize the grasping space inside the gripper; the outer continuous folding electrostatic hydraulic amplifier driver is used to make the soft grasping finger bend inward to grasp the target to be grasped; the body grasping finger pitch mechanism (3) is used to expand the inner space of the grasper grasping the object.

2. The biomimetic soft gripper according to claim 1, characterized in that, The fishbone-shaped soft skeleton has continuous fishbone-shaped skeletal slots on both the inner and outer sides relative to the soft grasping finger mounting position. The skeletal slots are rectangular and asymmetrically distributed on the inner and outer sides. The inner skeletal surface of the fishbone-shaped soft skeleton is a vertical plane, while the outer skeletal surface is an arch shape.

3. The biomimetic soft gripper according to claim 1, characterized in that, The fishbone-shaped soft skeleton, the swinging soft layer, and the fixing layer are integrally printed by a 3D printer. The fishbone-shaped soft skeleton and the swinging soft layer are printed with soft 3D printing material, while the fixing layer is printed with hard 3D printing material.

4. The biomimetic soft gripper according to claim 1, characterized in that, The horizontal telescopic actuator (301) includes a Z-shaped continuous electrostatic hydraulic amplification actuator and a side plate. The horizontal telescopic actuator (301) is connected to the inner side of the fixing layer of the soft gripping finger (1) and the outer vertical plate of the guide rail fixing plate.

5. The biomimetic soft gripper according to claim 4, characterized in that, The sealing bags for the inner continuously folded electro-hydraulic amplifier actuator, the outer continuously folded electro-hydraulic amplifier actuator, the electro-hydraulic amplifier actuator located on the outside of the swing soft layer, and the Z-shaped continuous electro-hydraulic amplifier actuator are all made of TPU high-transparency polyurethane film.

6. The biomimetic soft gripper and its control method according to claim 1, characterized in that, It also includes a soft silicone waterproof sealant, an underwater detection camera, and a component control cabin.

7. The biomimetic soft gripper according to claim 6, characterized in that, The underwater detection camera is installed in the central circular hole area of ​​the soft silicone waterproof sealant and is connected to the soft silicone waterproof sealant by waterproof adhesive. The cable passes through the central circular hole of the soft gripping finger pitch-changing mechanism and connects to the component control compartment.

8. The biomimetic soft gripper according to claim 7, characterized in that, The component control compartment includes a communication interface, Raspberry Pi, expansion board, relays, serial port regulator, boost module, wiring serial port, and terminal blocks.

9. A control method for the bionic soft gripper according to any one of claims 1-8, characterized in that, Includes the following steps: (1) The mother ship carrying the bionic soft gripper moves to the target to be grabbed. The mother ship lowers the bionic soft gripper to the target by the winch. The depth of the bionic soft gripper in the water is recorded as H. (2) Control the underwater detection camera under the bionic soft gripper to capture underwater images and upload them to the host computer. Establish the distortion correction function of the wide-angle camera through the position of each marker point and perform distortion correction processing on the captured images. (3) Based on the preset marker points on the soft grasping finger and the pixel points of the target to be grasped, the distance from the marker points on the soft grasping finger to the target to be grasped in the image is determined by the reference object method after measurement and distortion processing. The actual height difference between the bionic soft grasping finger and the target to be grasped is converted by the similar triangle method. (4) Determine whether the actual height difference between the bionic soft gripper and the target to be grasped is greater than the height difference threshold. If the height difference is greater than Then control the mother ship to rotate the winch to continue lowering the bionic soft gripper; if the height difference is no greater than Proceed to step (5); (5) The host computer controls the underwater detection camera to capture underwater images. By capturing the images and the various markers of the soft grasping fingers, the horizontal distance parameters between the bionic soft grasper and the target to be grasped are obtained. The soft grasping finger closest to the target to be grasped is determined. The soft grasping finger works to make the bionic soft grasper swim to the top of the target to be grasped. (6) If the horizontal distance between the bionic soft gripper and the target to be grasped is within the horizontal distance threshold of the target to be grasped. If the distance is within the specified range, proceed to step (7); otherwise, repeat step (5) until the horizontal distance between the bionic soft gripper and the target being grasped is within the horizontal distance threshold. Inside; (7) Stop the movement of the bionic soft gripper. The electrostatic hydraulic amplifier driver located on the outside of the swinging soft layer expands and de-energizes the bionic soft gripper repeatedly, so that it rotates in place to find the gripping angle corresponding to the target and then stops rotating. (8) The Z-shaped continuous electrostatic hydraulic amplifier of the horizontal telescopic actuator in the four directions of the horizontal telescopic actuator is simultaneously energized and expanded, driving the guide rail slider and soft gripping finger connected to the horizontal telescopic actuator to move outward to the maximum position at the same time, expanding the inner space of the gripper to grasp the object. (9) After the finger pitch is changed, the inner continuous folding electrostatic hydraulic amplifier driver is simultaneously energized and expanded, and the grasping fingers bend and open outward to maximize the grasping space inside the gripper. (10) The mother ship rotates the winch to continue lowering the bionic soft gripper to the bottom. The inner continuous folding electrostatic hydraulic amplifier driver is de-energized, and the soft gripping finger returns to its original shape. At the same time, the outer continuous folding electrostatic hydraulic amplifier driver is energized and expands, and the soft gripping finger bends inward to grasp the target to be grasped.

10. The control method for the bionic soft gripper according to claim 9, characterized in that, In step (5), after determining which soft grasping finger is more inclined towards the target to be grasped, the soft grasping finger works, causing the bionic soft grasper to move to directly above the target to be grasped, as follows: (51) The electrostatic hydraulic amplifier actuator on the same side of the soft layer controls the swing of all soft grasping fingers, and continuously energizes and de-energizes them multiple times, causing the bionic soft gripper to rotate in place, so that the soft grasping finger closest to the target rotates to an angle with the target at the angle threshold. Within the range; (52) Control the continuous folding electrostatic hydraulic amplifier driver on the inner side of the soft grasping finger to continuously energize and de-energize, so that the bionic soft grasping hand moves to the direction of the target to be grasped and directly above the target.

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