A soft robot with variable configuration and rigid-flexible coupling

Abstract

The application discloses a variable-configuration rigid-flexible coupling soft hand, comprising a plurality of rigid-flexible coupling soft fingers, a switching frame system and a superstructure energy-absorbing palm, the roots of the plurality of rigid-flexible coupling soft fingers are connected with the switching frame system, the superstructure energy-absorbing palm is arranged on the switching frame system and located inside a space surrounded by the plurality of rigid-flexible coupling soft fingers, and the switching frame system is used for driving the plurality of rigid-flexible coupling soft fingers to switch between a first configuration and a second configuration; the first configuration is that the plurality of rigid-flexible coupling soft fingers are parallel to each other and are used for soft covering and grabbing a static target; and the second configuration is that the plurality of rigid-flexible coupling soft fingers converge towards each other to form a cage-shaped configuration and are used for capturing a dynamic target. The application solves the problem that a single gripper is difficult to simultaneously achieve soft grabbing of a static target and efficient capturing of a dynamic target.

Description

Technical Field

[0001] This invention relates to the field of robotics, specifically to a soft robotic hand for grasping and capturing targets, and more particularly to a modulating soft hand capable of switching configurations according to the target state (static or dynamic) to achieve stable grasping and efficient capture. Background Technology

[0002] With the advancement of technology and the needs of production and daily life, soft grippers have gained widespread attention due to their superior properties and potential scientific research and production value compared to traditional rigid mechanical grippers. As a cutting-edge design approach, rigid-flexible coupling endows soft grippers with many excellent characteristics that overcome their inherent disadvantages, providing a feasible solution for multimodal gripping and dexterous operation of soft grippers, and has great development prospects.

[0003] Traditional rigid grippers have a long history of development and wide application, dominating industrial production for a long time due to their high precision and excellent performance. However, rigid manipulators struggle to adapt to safe interactions in unstructured environments, exhibit poor grasping ability against complex, irregularly shaped, and fragile objects, easily causing damage to operators, the environment, and the manipulated objects. The transformative breakthrough of soft grippers has garnered widespread attention. With their inherent adaptability and continuous compliant deformation characteristics, soft grippers have become one of the most mainstream research directions for compliant operation, human-machine interaction, and applications in unstructured environments. Currently, soft grippers can be mainly divided into two structural types: soft and rigid-flexible coupling. However, existing soft grippers, whether purely soft or rigid-flexible coupled, primarily focus on grasping static targets. When facing high-speed moving dynamic targets, these grippers often lack sufficient response speed, cannot quickly form an effective constraint space, and lack efficient energy absorption mechanisms to dissipate the target's kinetic energy, leading to capture failure or target rebound.

[0004] Therefore, there is an urgent need in this field for an innovative gripper solution that can combine the advantages of compliant precision when gripping static targets with the rapid response and high energy absorption capability when capturing dynamic targets. Summary of the Invention

[0005] The technical problem this invention aims to solve is how to overcome the shortcomings of existing soft grippers in effectively balancing compliant grasping of static targets and efficient capture of dynamic targets. Specifically, it addresses how to enable a gripper to safely and adaptively grasp static objects like a traditional soft hand, while also being able to quickly switch to a configuration that absorbs some kinetic energy through the deformation of the soft fingers and completely dissipates the remaining kinetic energy through the palm structure when facing dynamic targets, thereby achieving a stable passive capture.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A flexible-rigid coupling soft hand with variable configuration includes: a plurality of flexible-rigid coupling soft fingers, a switching frame system, and a superstructure energy-absorbing palm; the roots of the plurality of flexible-rigid coupling soft fingers are connected to the switching frame system; the superstructure energy-absorbing palm is disposed on the switching frame system and located within the space enclosed by the plurality of flexible-rigid coupling soft fingers; the switching frame system is used to drive the plurality of flexible-rigid coupling soft fingers to switch between a first configuration and a second configuration; the first configuration is in which the plurality of flexible-rigid coupling soft fingers are parallel and opposite each other, used for static target grasping; the second configuration is in which the plurality of flexible-rigid coupling soft fingers converge to form a cage-like configuration, used for dynamic target capture. In dynamic target capture, the dynamic target first contacts the flexible-rigid coupling soft fingers, and part of its kinetic energy is absorbed by the deformation of the flexible-rigid coupling soft fingers, and then collides with the superstructure energy-absorbing palm, and its remaining kinetic energy is dissipated and absorbed by the superstructure energy-absorbing palm, thus completing the capture.

[0008] In some embodiments, at least one of the following technical means is also included:

[0009] The rigid-flexible coupling soft body includes a gripping part and a swinging part; the gripping part includes a strain limiting layer, a deformation layer, multiple rigid blocks and an elastic rebound member seamlessly bonded from bottom to top, the stiffness of the deformation layer is less than the stiffness of the strain limiting layer; the gripping part is provided with at least one gripping drive chamber; the elastic rebound member is arranged along the length direction of the gripping part; the swinging part includes an exoskeleton restraint sheath and a soft actuator, the exoskeleton restraint sheath is sleeved on the soft actuator, and the swinging part is provided with at least one pneumatic drive chamber.

[0010] The plurality of hard blocks are hard dovetail blocks, and two adjacent hard dovetail blocks are engaged with each other by a protrusion and a groove, and there is a gap between two adjacent hard dovetail blocks.

[0011] The pneumatic drive chamber within the swing section is an inclined air chamber, and the axis of the inclined air chamber forms an acute angle with the length direction of the swing section.

[0012] The superstructure energy-absorbing palm includes a cell array, which is composed of multiple three-dimensional cell units arranged in an array. Each three-dimensional cell unit includes a rigid exoskeleton, a soft phase energy dissipation structure, and a rigid energy absorption structure. The soft phase energy dissipation structure and the rigid energy absorption structure are both disposed within the space enclosed by the rigid exoskeleton, and the rigid energy absorption structure is engaged with the rigid exoskeleton through a snap-locking mechanism.

[0013] The soft phase energy dissipation structure includes two buckling beams arranged in a cross shape.

[0014] The cell array of the superstructure energy-absorbing palm is divided into multiple layers in the thickness direction, and the three-dimensional cell units in different layers have different mechanical response characteristics.

[0015] The cell array of the superstructure energy-absorbing palm, from top to bottom, includes: a contact layer with negative stiffness characteristics, a buffer layer with quasi-zero stiffness characteristics, and a support layer with positive stiffness characteristics.

[0016] The switching frame system includes a multi-link mechanism, a synchronization ring, a fixed ring, at least one elastic element, and a position locking mechanism; one end of the multi-link mechanism is connected to the rigid-flexible coupling soft finger, and the other end is connected to the synchronization ring; the synchronization ring is slidably sleeved on the fixed ring; the elastic element provides an elastic force to the synchronization ring to make it tend toward the first configuration; the position locking mechanism is used to lock the synchronization ring at a position corresponding to the first configuration or the second configuration.

[0017] The position locking mechanism is a pin self-locking mechanism, including a double-hole limiting lever, a locking pin, and an elastic driving member; the double-hole limiting lever is installed on the fixed ring and has two limiting holes; the locking pin can selectively engage with one of the limiting holes under the action of the elastic driving member to achieve position locking.

[0018] The present invention also adopts the following technical solutions:

[0019] A robotic system includes: a robotic arm; and a rigid-flexible coupled soft hand, as described in any of the above, for grasping dynamic and static targets, mounted at the end of the robotic arm.

[0020] The present invention also adopts the following technical solutions:

[0021] A method for grasping a target object using a rigid-flexible coupled soft hand as described in any of the above methods includes the following steps: determining whether the target object is a static target or a dynamic target; if the target object is a static target, controlling the switching frame system to switch the rigid-flexible coupled soft hand to the first configuration, and controlling the pneumatic drive chamber of the rigid-flexible coupled soft hand to inject driving air pressure to cause it to bend and deform, so as to cover and grasp the static target; if the target object is a dynamic target, controlling the switching frame system to switch the rigid-flexible coupled soft hand to the second configuration, so that the dynamic target first contacts the rigid-flexible coupled soft hand, and part of its kinetic energy is absorbed by the deformation of the rigid-flexible coupled soft hand, and then collides with the superstructure energy-absorbing palm, and its remaining kinetic energy is dissipated and absorbed by the superstructure energy-absorbing palm, thus completing the capture.

[0022] Furthermore, the step of determining whether the target object is a static or dynamic target is achieved by acquiring and processing image information of the target object through a vision sensor integrated on the robot system.

[0023] The present invention also adopts the following technical solutions:

[0024] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described above.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] The switching frame system drives multiple rigid-flexible coupled soft fingers to switch between a parallel, opposing first configuration and a converging, cage-like second configuration, enabling the rigid-flexible coupled soft fingers to employ different capture strategies for static and dynamic targets. For static targets, the rigid-flexible coupled soft fingers in the first configuration perform active and compliant enveloping grasping; for dynamic targets, the cage-like space formed by the second configuration allows the dynamic target to first contact the rigid-flexible coupled soft fingers, which have passive deformation energy absorption capabilities, to absorb some kinetic energy and initially restrict its movement, and then collide with the superstructure energy-absorbing palm located inside, efficiently dissipating and absorbing the remaining kinetic energy, thereby achieving a high success rate and high adaptability in capturing both static and dynamic targets with a single gripper. This synergistic effect of "configuration switching + passive energy absorption" is the key to achieving the top-level beneficial effects of this application.

[0027] Furthermore, the specific structure of the rigid-flexible coupling soft body enables it to provide greater gripping force and coverage area when grasping the target object, and can passively deform to absorb energy when impacted and quickly rebound and reset after impact.

[0028] Furthermore, the multi-layer cell array design of the superstructure energy-absorbing palm enables sequential mechanical response, absorbing and dissipating impact energy step by step, and preventing energy rebound through a snap-locking mechanism. This multi-layered, lockable deformation mechanism significantly improves energy absorption efficiency.

[0029] Furthermore, the switching frame system adopts a mechanical self-locking mechanism, which enables rapid, stable, and low-energy switching and locking of configurations. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the front view structure of the rigid-flexible coupling software finger provided in the embodiment of the present invention.

[0031] Figure 2 This is a cross-sectional view of the rigid-flexible coupling software finger provided in an embodiment of the present invention.

[0032] Figure 3 This is a side view structural diagram of the rigid-flexible coupling software finger provided in an embodiment of the present invention.

[0033] Figure 4This is a schematic diagram of the main view structure of the superstructure energy-absorbing palm provided in an embodiment of the present invention.

[0034] Figure 5 This is a cross-sectional view of the superstructure energy-absorbing palm provided in an embodiment of the present invention.

[0035] Figure 6 This is a top view structural diagram of the superstructure energy-absorbing palm provided in an embodiment of the present invention.

[0036] Figure 7 This is an axonometric structural schematic diagram of the superstructure energy-absorbing palm provided in an embodiment of the present invention.

[0037] Figure 8 This is a front view structural diagram of the switching frame system provided in an embodiment of the present invention.

[0038] Figure 9 This is a top view structural diagram of the switching frame system provided in an embodiment of the present invention.

[0039] Figure 10 This is a cross-sectional view of the self-locking mechanism for pins provided in an embodiment of the present invention.

[0040] Figure 11 This is a front view structural diagram of the rigid-flexible coupling software provided in the embodiment of the present invention, which is in the first configuration (parallel state).

[0041] Figure 12 This is a front view structural diagram of the rigid-flexible coupling software provided in the embodiment of the present invention, which is in the second configuration (cage state).

[0042] Figure 13 This is a schematic diagram of the force and displacement curves of the three-dimensional unit cell of the superstructure energy-absorbing palm provided in the embodiment of the present invention.

[0043] Figure 14 This is a schematic diagram comparing the energy absorption efficiency of the superstructured energy-absorbing palm provided in this embodiment of the invention with that of a comparative material.

[0044] Explanation of reference numerals in the attached figures:

[0045] 1. Rigid dovetail block; 2. Elastic tendon; 3. Deformation layer; 4. Connector; 5. Finger tip connector; 6. Air cavity deformation layer unit; 7. Exoskeleton constraint sheath; 8. Strain limiting layer; 9. Rigid phase contact plate; 10. Rigid exoskeleton; 11. Buckling beam; 12. Snap-on cantilever beam; 13. Snap-on locking mechanism; 14. Second link of multi-link mechanism; 15. Third link of multi-link mechanism; 16. Fourth link of multi-link mechanism; 17. Compression spring; 18. Guide rail; 19. Synchronization ring; 20. Silicone bellows; 21. Foot support; 22. Pin self-locking mechanism; 23. Double-hole limit lever; 24. Fixing ring; 25. End cap; 26. Pin box end cap; 27. Fixing pin; 28. Locking pin; 29. ​​Paddle. Detailed Implementation

[0046] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope and application of the present invention.

[0047] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component. Furthermore, a connection can be used for both fixing and circuit / signal connectivity.

[0048] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0049] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0050] In this article, the rigid-flexible coupling soft finger is sometimes simply referred to as the soft finger, and the superstructure energy-absorbing palm is sometimes simply referred to as the palm.

[0051] The basic concept of the embodiments of the present invention is as follows:

[0052] A flexible-rigid coupling soft hand with variable configuration for grasping dynamic and static targets, the overall structure of which is as follows: Figure 11 and Figure 12 As shown, the rigid-flexible coupled soft hand includes rigid-flexible coupled soft fingers, a superstructure energy-absorbing palm, and a switching frame system, wherein:

[0053] like Figure 1 , Figure 2 and Figure 3 As shown, the rigid-flexible coupling soft body includes a gripping part that can bend forward and backward and a swinging part that can bend left and right. The gripping part is seamlessly integrated from bottom to top, consisting of a strain-limiting layer 8 with three rows of protrusions at the front end, a concave deformation layer 3, multiple rigid blocks (such as convex rigid dovetail blocks 1), and an outermost elastic rebound component (such as an elastic tendon 2). The swinging part, which can bend left and right, includes an exoskeleton restraint sheath 7 and a soft actuator. The exoskeleton restraint sheath 7 has biomimetic transverse and spinous processes on its upper and lower sides. Adjacent exoskeleton restraint sheaths 7 are connected by hinges and fitted over the soft actuator. The air chamber of the deformation layer of the soft actuator is an oblique air chamber. The material stiffness of the deformation layer 3 of the gripping part is much smaller than that of the strain-limiting layer 8.

[0054] The soft actuator itself employs a layered composite structure similar to the gripper, seamlessly bonded together with an inner air cavity deformation layer unit 6 and an outer central restraining layer. The air cavity deformation layer unit 6 contains the aforementioned oblique air cavity, and its material is relatively soft with a low Young's modulus; while the central restraining layer has a significantly higher Young's modulus and greater stiffness than the air cavity deformation layer unit 6. This design principle is the same as that of the gripper: when driving air pressure is injected into the oblique air cavity on one side, the soft air cavity deformation layer unit 6 undergoes significant expansion and deformation, while the rigid central restraining layer deforms very little. This difference in deformation forces the entire swinging part to bend towards the restraining layer. The main function of the exoskeleton restraint sheath 7 is to limit the amplitude of this bending, prevent excessive radial expansion, and provide longitudinal support.

[0055] As a preferred technical solution, the rigid dovetail block 1 has a flat protrusion at the front and a groove at the rear. This allows adjacent rigid dovetail blocks 1 to engage in a tenon-and-mortise manner, with a gap of 0.5-2mm. This gap size ensures that when the gripping part moves within a predetermined bending range, the rigid blocks do not interfere with each other while maintaining effective force transmission. When the gripping part bends inward, the rigid dovetail blocks do not interfere and do not hinder the inward bending of the gripping part. The elastic tendon 2 stretches when the gripping part bends inward, producing a certain rebound effect. This rebound effect will slightly hinder the inward gripping action of the gripping part, but due to its low Young's modulus, this weakening is not significant and can be compensated for by slightly increasing the driving air pressure (e.g., 5KPa).

[0056] The soft gripping and swinging parts can be orthogonally arranged using connector 4. Connector 4 is interference-fitted with the soft brake of the swinging part and the end of the soft part of the gripping part, respectively. It has three channels inside, which provide space for the driving air passage of one gripping drive chamber of the gripping part and the driving air passage of the two pneumatic drive chambers of the swinging part. The rigid dovetail block 1 at the root of the gripping part is engaged with connector 4 by a pin. The exoskeleton constraint sheath 7 of the swinging part is a ring-shaped bone sleeve. The last ring-shaped bone sleeve at the root of the swinging part is engaged with connector 4 by a locking pin.

[0057] Both pneumatic drive chambers (left and right) of the swing section are inclined air chambers, with the axis of each inclined air chamber forming an acute angle with the length direction of the swing section. Preferably, the inclination angle of the inclined air chamber is 30-60°. This angle is optimized to effectively convert the expansion force of the air chamber into a larger swing torque under the same air pressure. Because of the inclined air chamber design, the lateral displacement component is greater than the radial displacement component during expansion, thus converting the expansion force into swing torque more effectively. Therefore, a larger swing angle can be obtained under the same air pressure than with a straight air chamber. When driving air pressure is input to the left pneumatic drive chamber of the swing section of the flexible finger, the left pneumatic drive chamber (inclined air chamber) expands and deforms, resulting in a corresponding left-side swing. Correspondingly, when driving air pressure is input to the right pneumatic drive chamber (inclined air chamber) of the swing section, a corresponding right-side swing occurs. When the air passage of the gripping part is supplied with driving air pressure, the gripping drive chamber of the gripping part expands and outputs a greater gripping force under the action of the adjacent outwardly protruding hard dovetail block 1. This is because the hard structure has a higher force transmission efficiency compared to the deformation layer of the all-soft structure.

[0058] like Figure 4 , Figure 5 , Figure 6 and Figure 7 As shown, the superstructure energy-absorbing palm design for the upper part of the rigid-flexible coupled soft hand is composed of a three-dimensional unit cell array. Each three-dimensional unit cell includes a rigid outer skeleton, a soft phase energy dissipation structure, and a rigid energy absorption structure. Each three-dimensional unit cell has a rigid phase contact plate 9 at its top, which is integrally formed with the rigid energy absorption structure below. Specifically, the rigid energy absorption structure is a snap-fit ​​cantilever beam 12, which is disposed within the space enclosed by the rigid outer skeleton 10, and the snap-fit ​​cantilever beam 12 is engaged with the rigid outer skeleton 10 via a snap-fit ​​locking mechanism 13. The unit cell size is 30 mm. 30mm 25mm. The soft phase energy dissipation structure specifically consists of two buckling beams 11 (crossbeams) arranged in a cross shape, which are disposed within the space enclosed by the rigid outer frame 10 and connected to the upper end of the rigid outer frame 10 and the upper end of the snap-fit ​​cantilever beam 12. The upper ends of the buckling beams 11 and the snap-fit ​​cantilever beam 12 are integrally formed with the rigid outer frame 10 through interlocking additive manufacturing, and the connection is firm and reliable.

[0059] The top of the rigid exoskeleton 10 is connected to the four ends of the buckling beam 11, and they converge at the bottom. In a preferred embodiment, the three-dimensional unit cells are arranged in a 3×3 row and column configuration and stacked in three layers to obtain a hierarchical array of superstructure energy-absorbing palm.

[0060] When a dynamic target impacts the energy-absorbing palm of the superstructure, the impact energy first causes the soft-phase energy dissipation structure (buckling beam 11) to buckle, dissipating some of the kinetic energy through viscoelastic damping. As the load increases, the hard energy-absorbing structure (clamping cantilever beam 12) undergoes elastic deformation and passes through the locking point of the clamping mechanism 13, absorbing a significant amount of energy within a short displacement. This is because for the same amount of elastic deformation, the energy absorption of the hard phase material is much higher than that of the soft phase material. After passing through the locking point, the unit cell completes the entire deformation process. The locking point and the clamping cantilever beam 12 have a 1.2 mm dimensional overlap to ensure reliable locking and to withstand the expected impact load without disengaging. The width and length of the buckling beam 11 are 8 mm and 15 mm, respectively. After deformation, the energy absorption of the palm exhibits a continuation of the buckling beam characteristics of the soft phase, buckling instability deformation, and remaining in a concave state. It is worth noting that although the deformation of the soft-phase buckling beam has bistable characteristics, it is susceptible to disturbance and instability. The locking cantilever beam 12 at the locking point hinders the cell's recovery, preventing the object's energy from recovering from the palm's potential energy. Further pressure is applied, and the response curve is dominated by the flexible beam being compressed and pulling the rigid outer skeleton, buckling, until the limit is reached. During this process, the structural stiffness of the unit continuously increases, and the curve slope continuously rises, eventually reaching a second singular peak. During the impact, the viscoelastic deformation and buckling instability of the soft-phase buckling beam dissipate some kinetic energy (converting it into heat). Subsequently, the rigid locking cantilever beam undergoes elastic deformation and passes through the locking point, absorbing a large amount of kinetic energy and storing it primarily as elastic potential energy. Crucially, the locking mechanism 13 prevents the structure's elastic recovery after deformation, preventing the stored elastic potential energy from being released back to the target object, thus effectively preventing rebound. This synergistic mechanism of "soft-phase dissipation + hard-phase absorption and locking" achieves efficient absorption and dissipation of kinetic energy.

[0061] Here, the triggering energy barrier for cell deformation can also be controlled by adjusting the length of the latching cantilever beam and the size of the latching radius. Considering the practical scenario, the mechanical response sequence of the palm is a top-down sequential response. The top layer, as the contact layer, has a lower latching energy barrier and negative stiffness characteristics, enabling a more sensitive response and initial energy absorption. The middle layer, as a buffer structure, possesses a moderate energy barrier and quasi-zero stiffness characteristics. The bottom layer matches a positive stiffness buckling beam and the highest energy barrier to resist high-energy impacts and provide final restraint, while also providing stable support for the first two layers.

[0062] like Figure 8 , Figure 9 and Figure 10 As shown, for the form switching and overall frame switching system of the rigid-flexible coupled soft hand, the four soft fingers are bolted to the four circumferential multi-link mechanisms of the switching frame system, and the hinges of adjacent link fingertips are also bolted together. After being assembled with the soft fingers, the multi-link mechanisms are connected to the bottom synchronization ring 19 and the fixed ring 24 respectively. The bottom of the fixed ring 24 is provided with an end cap 25. The synchronization ring 19 is connected to the fixed ring 24 through a pin self-locking mechanism 22. At the same time, the four slide rails also realize the circumferential fixation between the synchronization ring 19 and the fixed ring 24. There is a compression spring 17 between the four feet 21 at the bottom of the synchronization ring and the fixed ring, and the four compression springs 17 are distributed circumferentially. The guide rail 18 and the compression spring 17 are protected by a silicone bellows 20 sleeved on the outside. The top of the guide rail 18 has a blocking block, which is connected and locked by bolts to the internal threads of the guide rail. The pin self-locking mechanism 22 includes a double-hole limit lever 23 and a locking pin 28. The double-hole limiting lever 23 is mounted on the fixing ring 24 via a fixing pin 27. A lockable pin box end cover 26 is provided on one side of the pin self-locking mechanism 22 for easy installation and maintenance of the internal mechanism. The groove of the locking pin 28 engages with the lever 29, which contains a torsion spring. When the two limiting holes (upper and lower) of the double-hole limiting lever 23 are aligned with the locking pin 28, the lever 29 pushes the locking pin 28 in under the action of the torsion spring. At this time, the pin self-locking mechanism completes the limiting, and the rigid-flexible coupled soft hand is in a stable position. When the locking pin 28 is not aligned with the limiting holes of the double-hole limiting lever 23, under the action of the compression spring 17 on the upper part of the guide rail 18, the synchronizing ring drives the connected multi-link mechanism downward until the upper limiting hole of the double-hole limiting lever 23 engages with the locking pin 28. At this time, the soft hand is in a parallel relative state. To release the parallel locking state, lightly press the lever 29, and the limiting is released. After the limit is released, gently lift the synchronization ring 19. The synchronization ring 19 drives the multi-link mechanism to move upward. At this time, the soft fingers of the rigid-flexible coupled soft hand are arranged in a cage shape.

[0063] Example 1

[0064] In a preferred embodiment, ecoflex 00-30 special silicone is used as the elastic tendon, dragonskin 30 is selected as the deformation layer, Smooth-Sil 950 silicone is used to create the strain-limiting layer, and a rigid dovetail block 1 is 3D printed using ABS material. The driving air pressure of the rigid-flexible coupled soft hand is set to 30-60 kPa. When no driving air pressure is injected into the gripping part, it is in a taut state under the action of the elastic tendon. At this time, the front protrusion and rear groove of the adjacent rigid dovetail blocks engage with each other. The air source of the pneumatic control system can provide a positive pressure of 200 L / min and a negative pressure flow of 40 L / min, and the control method can adopt I / O control and level signal.

[0065] The hardness of the deformation layer 3 is Shore A 20-30, and the hardness of the strain confinement layer 8 is Shore A 70-80.

[0066] The Young's modulus of the central confinement layer of the swing section is greater than that of the air cavity deformation layer unit 6 of the swing section, and it is responsible for providing greater bending deformation under the driving air pressure. Therefore, under the same internal air pressure, the deformation of the air cavity deformation layer unit 6 of the swing section is greater than that of the confinement layer, and the swing section bends accordingly.

[0067] The Young's modulus of the deformation layer 3 of the gripping part is also smaller than that of the strain-limiting layer 8. Therefore, under the same air pressure, the bending deformation of the deformation layer 3 is greater than that of the strain-limiting layer 8. Upon injection of driving air pressure, the gripping part bends inward to grasp the corresponding object.

[0068] The convex hard dovetail block 1 can hinder the expansion of the deformation layer 3, requiring greater driving air pressure to achieve the same shape in the gripping part. The introduction of the convex hard dovetail block 1 improves the force transmission efficiency and increases the gripping force and fingertip force of the gripping part.

[0069] The three protruding structures at the ends of strain-limiting layer 8 help to hook the object and increase friction to some extent. The cross-sectional area of ​​the entire soft finger gradually narrows from the root to the tip, and compared to a straight column, it has a greater curvature under the same air pressure, providing a larger coverage area.

[0070] The elastic tendon 2, fitted at the top of the rigid dovetail block 1, releases its elastic potential energy when the driving air pressure is removed, allowing the soft finger to return to a straight state. Once back in the straight state, the rigid dovetail blocks 1 interlock and prevent further backward bending of the gripping part. When the gripping part bends, the rebound effect of the elastic tendon 2 weakens the gripping force. However, the elastic tendon has a very low Young's modulus, and this weakening effect can be offset by a slight increase in the driving air pressure.

[0071] The exoskeleton constraint sheaths 7 of the swinging parts are hinged together, and have biomimetic spinal structures at the upper and lower ends to limit the over-expansion of the air cavity deformation layer units 6 of the swinging parts to the left and right. When bending to the left to a certain extent, the left-side protrusions of the biomimetic structure at the upper end of the exoskeleton constraint sheath 7 interfere with each other, limiting further expansion. A similar phenomenon occurs when bending to the right to a certain extent. When subjected to longitudinal load, the protrusions in the middle of the exoskeleton constraint sheath 7 interfere with each other, exhibiting rigidity and increasing the load. The root of the soft finger is press-fitted with the fingertip connector 5, which connects to the switching frame system. The fingertip connector 5 acts as the drive link of the multi-link mechanism.

[0072] In its normal state, the compression spring 17 on the upper half of the guide rail 18 presses down on the synchronous ring 19, and the upper limit hole of the double-hole limit lever 23 of the self-locking mechanism 22 engages with the locking pin 28, putting the rigid-flexible coupled soft hand in a stable state. At this time, the soft fingers are parallel to each other, allowing them to grasp various static objects. The swinging part can swing left and right, driving the gripping part to complete a grasping action similar to that of a human hand. The graded curvature bending of the gripping part can complete grasping and hooking actions similar to those of a human hand.

[0073] The configuration switching operation is as follows:

[0074] Switching from the first configuration (parallel) to the second configuration (cage-like): Gently move the lever 29 to disengage the locking pin 28 from the "upper limit hole" of the double-hole limiting lever 23. At this point, the operator can lift the synchronizing ring 19 upwards, overcoming the slight resistance of the compression spring 17, and drive the multi-link mechanism until the locking pin 28 aligns with the lower limit hole of the double-hole limiting lever 23. Under the action of the elastic drive element (torsion spring), it automatically engages and locks. The lever 29 drives the locking pin 28 into the lower limit hole. At this point, the rigid-flexible coupled soft hand is in a stable state. The multi-link mechanism includes the fingertip connector 5, the second link 14, the third link 15, and the fourth link 16. During the upward movement, the synchronizing ring 19 drives the fingertip connector 5, the second link 14, the third link 15, and the fourth link 16 to expand outwards. When the limiting hole engages, the soft fingers converge at a single point, at which point the soft fingers are in a stable position. Figure 12 The second configuration shown is a cage-like configuration.

[0075] When the rigid-flexible coupled soft hand is in a cage-like configuration, the swinging part of the soft fingers exposes the hard contact plate 9 on the palm. When an external object impacts the soft fingers, the soft fingers will compliantly bend inward. After the object leaves contact with the soft fingers, the soft fingers will quickly return to a straight position under the action of the elastic tendon 2. Under the locking action of the hard dovetail block 1, the soft fingers will not bend further outward. Then, the superstructure energy-absorbing palm collides with the object. In the reversible steady-state deformation, part of the impact energy is consumed, and the other part of the energy is stored in the palm.

[0076] If the superstructure energy-absorbing palm cannot process the energy of an object to bring it to a standstill, the object will rebound. When the rebounding object impacts the soft fingers, the soft fingers exhibit rigid characteristics under the locking action of the hard dovetail block 1, hindering the object's escape. The deformation of the superstructure energy-absorbing palm is a sequential compression of a three-layer structure, namely, compression from the first layer (contact layer) to the second layer (buffer layer) and then to the third layer (support layer). The compression of a single layer is manifested as a response characteristic from the buckling of the soft phase buckling beam 11 under pressure to the engagement of the snap-fit ​​cantilever beam 12 through the snap-fit ​​locking mechanism 13, and then to the buckling of the hard outer skeleton 10.

[0077] Switching back to the first configuration from the second configuration: Gently flick the lever 29 again to disengage the locking pin 28 from the "lower limit hole". Under the restoring force of the compression spring 17, the synchronizing ring 19 will automatically move downward, driving the multi-link mechanism to reset until the locking pin 28 aligns with the "upper limit hole" and automatically engages and locks, restoring the soft finger to its original position. Figure 11 The parallel relative state is shown.

[0078] After the above configuration switching process is completed, the mechanism is in a stable locked state. Especially when switching from the second configuration (cage-like) back to the first configuration (parallel), as mentioned earlier, after unlocking, the system mainly relies on the restoring force of the compression spring 17 to achieve automatic reset, which is fast and energy-efficient. During the process, the synchronizing ring 19 drives the multi-link mechanism, specifically the fingertip connector 5, the second link 14, the third link 15, and the fourth link 16 of the multi-link mechanism, to retract inwards, restoring the soft fingers to a parallel and opposite state, allowing them to grasp static targets. The entire deformation process is completed quickly without the need for continuous power supply from an additional actuator.

[0079] Experimental verification:

[0080] When the rigid-flexible coupled soft hand is in a parallel state with its soft fingers pointing in the same direction, it can grasp objects of various shapes, including spheres, cylinders, and prisms. In this configuration, the gripping force for static targets can reach 5.5N, demonstrating good active output performance. When the gripper is in a cage-like configuration, it can capture dynamic targets. In experiments, it was able to capture objects with speeds ranging from 0.4m / s to 1.2m / s, sizes from 7cm to 25cm, and various shapes, with a capture success rate of 98%.

[0081] The superstructured energy-absorbing palm absorbs energy upon impact; the force-displacement curves of the unit cells that make up the palm are shown below. Figure 13 As shown.

[0082] To quantitatively evaluate the energy absorption performance of the superstructured energy-absorbing palm of this invention, we conducted a comparative experiment with palm structures of the same size made of pure soft-phase material (TPU) and pure hard-phase material (PLA). The experimental results are as follows: Figure 14 As shown in the diagram. In this comparative experiment, the horizontal axis represents the material type, from left to right: PLA and TPU dual-phase lattice materials, TPU soft-phase lattice material, and PLA hard-phase lattice material. The left vertical axis represents the impact block rebound height (unit: cm), and the right vertical axis represents the absorbed energy (unit: mJ). The height of the bars represents the numerical value. It can be seen that the pure PLA structure has high stiffness but poor toughness, and its total absorbed energy is about 134 mJ; the pure TPU structure is compliant but has a low overall stress level, and its total absorbed energy is about 169 mJ. In contrast, the palm of the present invention combines the advantages of both, and its total absorbed energy reaches about 204 mJ, which is significantly higher than that of the comparative materials: in the initial stage, the buckling deformation of the soft phase buckling beam provides a moderate buffer force and dissipates some energy; after the critical point, the hard energy-absorbing structure begins to dominate the deformation and generates a high, continuous plateau stress through the snap-locking mechanism, thereby efficiently absorbing energy over a large displacement range. Ultimately, the total area under the force-displacement curve of the palm of the present invention is significantly larger than that of the two comparative materials, demonstrating the huge advantage of its multi-layer composite and sequential response design in energy absorption efficiency, which is crucial for effectively dissipating the kinetic energy of dynamic targets.

[0083] Compared to a palm composed purely of soft-phase material TPU and pure hard-phase material PLA, the superstructure energy-absorbing palm proposed in this invention has a significant advantage in energy absorption.

[0084] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flexible-rigid coupling soft hand with variable configuration, characterized in that, include: Multiple rigid-flexible coupled soft fingers, a switching frame system, and a superstructure energy-absorbing palm; The roots of the multiple rigid-flexible coupled soft fingers are connected to the switching frame system; the superstructure energy-absorbing palm is disposed on the switching frame system and located inside the space enclosed by the multiple rigid-flexible coupled soft fingers; the switching frame system is used to drive the multiple rigid-flexible coupled soft fingers to switch between a first configuration and a second configuration; the first configuration is in which the multiple rigid-flexible coupled soft fingers are parallel and opposite each other, used for static target grasping; the second configuration is in which the multiple rigid-flexible coupled soft fingers converge to form a cage-like configuration, used for dynamic target capture. In dynamic target capture, the dynamic target first contacts the rigid-flexible coupled soft fingers, and part of its kinetic energy is absorbed by the deformation of the rigid-flexible coupled soft fingers. Subsequently, it collides with the superstructure energy-absorbing palm, and its remaining kinetic energy is dissipated and absorbed by the superstructure energy-absorbing palm, thus completing the capture.

2. The rigid-flexible coupled soft hand according to claim 1, characterized in that, The rigid-flexible coupling soft body includes a gripping part and a swinging part; the gripping part includes a strain limiting layer, a deformation layer, multiple rigid blocks and an elastic rebound member seamlessly bonded from bottom to top, the stiffness of the deformation layer is less than the stiffness of the strain limiting layer; the gripping part is provided with at least one gripping drive chamber; the elastic rebound member is arranged along the length direction of the gripping part; the swinging part includes an exoskeleton restraint sheath and a soft actuator, the exoskeleton restraint sheath is sleeved on the soft actuator, and the swinging part is provided with at least one pneumatic drive chamber.

3. The rigid-flexible coupled soft hand according to claim 2, characterized in that, The plurality of hard blocks are hard dovetail blocks, and two adjacent hard dovetail blocks are engaged with each other by a protrusion and a groove, and there is a gap between two adjacent hard dovetail blocks.

4. The rigid-flexible coupled soft hand according to claim 2 or 3, characterized in that, The pneumatic drive chamber within the swing section is an inclined air chamber, and the axis of the inclined air chamber forms an acute angle with the length direction of the swing section.

5. The rigid-flexible coupled soft hand according to claim 1, characterized in that, The superstructure energy-absorbing palm includes a cell array, which is composed of multiple three-dimensional cell units arranged in an array; each three-dimensional cell unit includes a rigid exoskeleton, a soft phase energy dissipation structure and a rigid energy absorption structure; Both the soft phase energy dissipation structure and the hard energy absorption structure are disposed within the space enclosed by the hard outer frame, and the hard energy absorption structure is engaged with the hard outer frame through a snap-locking mechanism.

6. The rigid-flexible coupled soft hand according to claim 5, characterized in that, The soft phase energy dissipation structure includes two buckling beams arranged in a cross shape.

7. The rigid-flexible coupled soft hand according to claim 5, characterized in that, The cell array of the superstructure energy-absorbing palm is divided into multiple layers in the thickness direction, and the three-dimensional cell units in different layers have different mechanical response characteristics.

8. The rigid-flexible coupled soft hand according to claim 7, characterized in that, The cell array of the superstructure energy-absorbing palm, from top to bottom, includes: a contact layer with negative stiffness characteristics, a buffer layer with quasi-zero stiffness characteristics, and a support layer with positive stiffness characteristics.

9. The rigid-flexible coupled soft hand according to claim 1, characterized in that, The switching frame system includes a multi-link mechanism, a synchronization ring, a fixed ring, at least one elastic element, and a position locking mechanism; one end of the multi-link mechanism is connected to the rigid-flexible coupling soft finger, and the other end is connected to the synchronization ring; the synchronization ring is slidably sleeved on the fixed ring; the elastic element provides an elastic force to the synchronization ring to make it tend toward the first configuration; the position locking mechanism is used to lock the synchronization ring at a position corresponding to the first configuration or the second configuration.

10. The rigid-flexible coupled soft hand according to claim 9, characterized in that, The position locking mechanism is a pin self-locking mechanism, including a double-hole limiting lever, a locking pin, and an elastic driving member; the double-hole limiting lever is installed on the fixed ring and has two limiting holes; the locking pin can selectively engage with one of the limiting holes under the action of the elastic driving member to achieve position locking.

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