Friction self-locking type self-adaptive winding soft body grabbing control method and grabbing device

Abstract

The invention provides a friction self-locking type self-adaptive winding soft body grabbing control method and a grabbing device, and belongs to the technical field of soft body grabbing robotics.The grabbing control method comprises the steps that a quantitative mapping model of bionic winding mechanics and a friction self-locking structure is established, and the soft body is grabbed on the basis of the soft body winding spiral configuration and the continuous contact force coupling effect; determining design parameters of the driving body-elastic fitting structure under unfolding and folding; self-adaptive fitting and local pressurization are cooperatively controlled; based on soft spiral winding dynamics and soft structure deformation, a force balance equation under multi-layer winding is obtained; therefore, a friction self-locking critical condition is obtained; the winding curvature of the clamping jaw is adjusted when the driving body and the elastic attaching structure make contact with an object, the friction self-locking structure and the flexible winding strategy are combined, friction self-locking can be triggered through structural deformation under the boundary condition, collaborative optimization of the operation space and the load capacity is achieved, and the mechanical arm has the advantages of being high in flexibility, high in adaptability and high in load capacity.

Description

Technical Field

[0001] The present invention relates to the technical field of soft body grasping robots, and in particular to a friction self-locking adaptive winding soft body grasping control method and a grasping device. Background Art

[0002] With increasing demands for adaptability to complex environments and safe human-machine interactions, soft robotics technology has rapidly emerged in the robotics field and achieved significant progress. With their unique flexible structures and excellent deformation capabilities, soft robots are able to better adapt to complex and changing environments. As core components of soft robotics, soft gripping robots, characterized by high compliance, environmental adaptability, and safe interaction with humans, have become a research hotspot. They also have enormous potential for application in industrial manufacturing, medical rehabilitation, food processing, and other fields.

[0003] Currently, most soft gripping devices are driven by pneumatic or rope drives. (1) They rely on material elasticity or air pressure, resulting in insufficient rebound force and poor gripping stability, especially in tilted or vibrating environments. (2) Most soft grippers lack active friction enhancement design, resulting in insufficient gripping force or the need for continuous energy input. (3) Existing winding structures are difficult to adapt to a wide range of sizes and complex shapes. It is necessary to propose a friction self-locking adaptive winding soft gripping control method and gripping device. Summary of the Invention

[0004] In order to address the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a friction self-locking adaptive winding soft body grasping control method and grasping device, which automatically adjusts the winding curvature after contacting the object by driving the main body and the elastic fitting structure. The friction self-locking structure is combined with the flexible winding strategy, which can trigger friction self-locking through structural deformation under boundary conditions, so that the load capacity is greater than the driving force, and the number of winding turns is optimized in real time, so that the gripper can achieve high-reliability grasping while fitting the contour of the object, and has the characteristics of high flexibility, strong adaptability and load capacity.

[0005] The present invention provides a friction self-locking adaptive winding soft body grasping control method, which includes: A quantitative mapping model of biomimetic winding mechanics and frictional self-locking structures was established. Based on the coupling of the soft body's winding spiral configuration and continuous contact force, the design parameters of the driving body and the elastically fitted structure under both expansion and contraction were determined. Adaptive fitting and local pressurization are coordinated and controlled. The second clamping jaw is driven to spirally wind by deflating the main body and contracting the elastic fitting structure. The winding curvature of the second clamping jaw is adjusted synchronously. The elastic fitting structure adaptively fits the surface contour of the object to be clamped. The end pneumatic unit performs local pressurization after winding to fix the object to be clamped. Based on the soft body spiral winding dynamics and soft body structural deformation, the friction coefficient between each gripper and the object to be clamped is established With winding angle The contact force friction model is used to obtain the force balance equation of friction force T and load force F under multi-turn winding: ; Where, is the friction coefficient between the second clamping jaw and the object to be clamped, is the friction coefficient between the first and second jaws, is the winding angle between the second clamping jaw and the object to be clamped, , is the thickness error angle of the second jaw; The critical condition of friction self-locking of the soft gripping device is obtained through the force balance equation: <360°、 By optimizing the friction coefficient and design parameters, the operating space and load force are coordinated and optimized, and the soft gripping device is controlled to adaptively fit and grasp the object to be clamped.

[0006] Preferably, the quantitative mapping model of bionic winding mechanics and friction self-locking structure is: ; Where, is the tension on the second clamp in the i-th winding segment, is the force at the starting point of the i-th winding segment of the second clamping jaw, The tension on the second clamp in the i+1 winding segment, is the friction coefficient between the i+1th winding segment and the ith winding segment between the second clamping jaw and the object to be clamped.

[0007] Preferably, based on the parameter relationship between the driving body and the elastic fitting structure, the design parameters of the elastic fitting structure are obtained, specifically: ; Where P is the air pressure of the driving body, r is the radius of the driving body after expansion, l1 is the length of the driving body, l2 is the initial length of the elastic fitting structure, and k is the elastic coefficient of the elastic fitting structure.

[0008] Preferably, the winding angle θ of the soft gripping device under multiple windings is min for: .

[0009] Preferably, the force balance equation within each winding segment in the soft gripping device is: ; ; Where C0 is a constant term.

[0010] On the other hand, the present invention also provides a friction self-locking adaptive winding soft body grasping device, which includes a driving body, an end pneumatic unit, an elastic fitting structure, a first clamp and a second clamp, the elastic fitting structure is arranged on the first end face of the driving body, the outer surfaces of the driving body and the elastic fitting structure are wrapped with multiple annular parts, the end pneumatic unit is connected to the second end face of the driving body, the first clamp and the second clamp are symmetrically arranged on both sides of the driving body, the driving body, the end pneumatic unit, the elastic fitting structure and the annular part are arranged between the first clamp and the second clamp, based on the driving body-elastic fitting structure coupling driving characteristics, active control of the spiral motion form is achieved by adjusting the internal air pressure of the driving body.

[0011] Preferably, the length of the drive body is 850-900 mm, and the length of the terminal pneumatic unit is 80-120 mm.

[0012] Preferably, the length and width of the first clamping jaw and the second clamping jaw are both greater than the length and width of the driving body.

[0013] Preferably, the driving body and the terminal pneumatic unit are both double-layer pneumatic driving structures.

[0014] Compared with the prior art, the beneficial effects of the present invention are embodied in: 1. This invention's friction-self-locking, adaptive wrapping soft gripping control method generates multiple wraps around the object to be gripped, and under specific circumstances, triggers frictional self-locking through structural deformation, thereby enhancing gripping reliability and stability. Furthermore, the use of silicone material as the second gripping jaw effectively increases friction with the object. The design employs a terminal pneumatic unit. When the soft gripping device grasps irregularly shaped objects, pressurizing the terminal pneumatic unit provides additional normal pressure, increasing friction with the object.

[0015] 2. The friction-locking, adaptive winding soft gripping device of the present invention adopts a fully flexible structural design that can effectively reduce damage to the object to be clamped. The elastic fitting structure and the driving body are divided into multiple sections through multiple ring parts, which can effectively adjust the winding and curling angles, and has high environmental adaptability and human-computer interaction safety.

[0016] 3. The friction-locking, adaptive winding soft gripping device of the present invention achieves extension and winding of the soft gripping device by increasing and decreasing the pressure of the driving body, avoiding the grasping mode similar to traditional pneumatic or wire-driven soft grippers that rely on the strength of the driving source. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the overall structure of the friction self-locking adaptive winding soft gripping device of the present invention; Figure 2 This is a flow chart for preparing the friction self-locking adaptive winding soft gripping device of the present invention; Figure 3 This is a force analysis diagram of the friction self-locking adaptive winding soft gripping device of the present invention; Figure 4 This is a fitting diagram of the relationship between the friction coefficient and the winding angle of the friction self-locking adaptive winding soft gripping device of the present invention; Figure 5 This is a test diagram of the friction self-locking adaptive winding soft gripping device of the present invention grasping different types of objects; Figure 6 This is a load force test diagram of the friction self-locking adaptive winding soft gripping device of the present invention in the self-locking state; Figure 7 This is a comparative test diagram of the gripping of the friction self-locking adaptive winding soft gripping device of the present invention in single-branch mode; Figure 8 This is a comparative test diagram of the gripping of the friction self-locking adaptive winding soft gripping device of the present invention in double-branch mode; Figure 9 This is a load test diagram of the friction self-locking adaptive winding soft gripping device of the present invention in the double-branch collaborative mode.

[0018] Reference numerals: 1. Driving body; 2. Terminal pneumatic unit; 3. Elastic fitting structure; 4. Ring member; 5. First clamping jaw; 6. First air inlet pipe; 7. Second air inlet pipe; 8. Second clamping jaw. DETAILED DESCRIPTION

[0019] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0020] The friction self-locking adaptive winding soft gripping device of the present invention is as follows: Figure 1As shown, it includes a drive body 1, a terminal pneumatic unit 2, an elastic fitting structure 3, an annular member 4, a first clamping jaw 5, and a second clamping jaw 8. The elastic fitting structure 3 is arranged on the first end face of the drive body 1. Multiple annular members 4 are evenly wrapped around the outer surfaces of the drive body 1 and the elastic fitting structure 3. The terminal pneumatic unit 2 is connected to the second end face of the drive body 1. The first clamping jaw 5 and the second clamping jaw 8 are symmetrically arranged on either side of the drive body 1. The drive body 1, the terminal pneumatic unit 2, the elastic fitting structure 3, and the annular member 4 are arranged between the first clamping jaw 5 and the second clamping jaw 8. The second end face of the drive body 1 is provided with a first air intake pipe 6 and a second air intake pipe 7. The drive body 1 and the terminal pneumatic unit 2 are both made of nylon fabric. The length of the drive body 1 is 850-900 mm, and the length of the terminal pneumatic unit 2 is 80-120 mm. The length and width of the first clamping jaw 5 and the second clamping jaw 8 are both greater than those of the drive body 1. The ring member 4 is a metal ring, arranged in a series of intervals, and its winding motion takes on a spiral shape, gradually expanding or contracting as the air pressure rises and falls. This spiral motion is controlled by adjusting the air pressure within the driver body. When the air pressure rises, the driver body 1 radially expands, resisting the contraction force of the elastically conformable structure 3, causing it to gradually expand. When the air pressure drops, the contraction force of the elastically conformable structure 3 dominates, causing the driver body 1 to transition to a wound state.

[0021] like Figure 2 As shown, the preparation method of the friction self-locking adaptive winding soft gripping device of the present invention comprises the following steps: S1. Fabricate the drive body 1 and the terminal pneumatic unit 2: Using a high-frequency machine, place two pieces of nylon cloth with their TPU-coated sides facing each other. Press the three edges of the two pieces together using a flat-end mold. Insert the first and second air intake pipes 6 and 7 through the unsealed short edges of the drive body 1 and terminal pneumatic unit 2, respectively. Finally, replace the flat-end mold with a mold with a 6mm diameter groove to seal the edges of the air intake pipes.

[0022] S2. Connecting the Inner Components: After stretching the elastic fitting structure 3, secure it to the first end face of the drive body 1 using multiple rings and glue, evenly distributing the ring members 4. Next, align the end pneumatic unit 2 with the upper side of the drive body 1 and secure it to the second end face of the drive body 1 using glue.

[0023] S3. Overall Encapsulation: Place the connected encapsulated components between the first and second jaws 5, 8, with the side with the end pneumatic unit 2 positioned close to the second jaw 8 and the side with the elastic fitting structure 3 positioned close to the first jaw 5. Glue the four edges of the first and second jaws 5, 8 together, allowing the first and second air inlet pipes 6 and 7 to extend. Once the glue has dried, the soft gripping device is complete.

[0024] like Figure 3 As shown, the friction self-locking adaptive winding soft body grasping control method includes: S1. Establish a quantitative mapping model between bionic winding mechanics and friction self-locking structure, specifically: .

[0025] Where, is the tension on the second clamp in the i-th winding segment, is the force at the starting point of the i-th winding segment of the second clamping jaw, The tension on the second clamp in the i+1 winding segment, is the friction coefficient between the i+1th winding segment and the ith winding segment between the second clamping jaw and the object to be clamped.

[0026] Based on the coupling effect of the soft body's winding spiral configuration and the continuous contact force, the design parameters of the driving body 1 and the elastic conforming structure 3 under expansion and contraction are determined respectively; based on the parameter relationship between the driving body 1 and the elastic conforming structure 3, the design parameters of the elastic conforming structure are obtained, specifically: .

[0027] Where P is the air pressure of the driving body, r is the radius of the driving body after expansion, l1 is the length of the driving body, l2 is the initial length of the elastic fitting structure, and k is the elastic coefficient of the elastic fitting structure.

[0028] S2, adaptive fitting and local pressurization coordinated control, by driving the main body 1 to deflate and the elastic fitting structure 3 to contract, driving the second clamping jaw to spirally wind, synchronously adjusting the winding curvature of the second clamping jaw 8, and adaptively fitting the surface contour of the object to be clamped through the elastic fitting structure 3, the end pneumatic unit 2 performs local pressurization after winding to fix the object to be clamped.

[0029] S3. Based on the soft body spiral winding dynamics and soft body structural deformation, establish the friction coefficient between each gripper and the object to be clamped With winding angle The contact force friction model is used to obtain the force balance equation of friction force T and load force F under multi-turn winding: .

[0030] Where, is the friction coefficient between the second clamping jaw and the object to be clamped, is the friction coefficient between the first and second jaws, is the winding angle between the second clamping jaw and the object to be clamped, , is the thickness error angle of the second jaw.

[0031] The winding angle θ of the soft gripping device under multi-turn winding min for: .

[0032] The force balance equation within each winding segment in the soft grasping device is: ; .

[0033] Where C0 is a constant term.

[0034] S4. The critical condition for frictional self-locking of the soft gripping device is obtained through the force balance equation: <360°、 By optimizing the friction coefficient and design parameters, the operating space and load force are coordinated and optimized, and the soft gripping device is controlled to adaptively fit and grasp the object to be clamped.

[0035] The winding configuration of the soft gripping device is adjusted by adjusting the spatial arrangement of the elastic fitting structure 3. When the elastic fitting structure 3 and the driving body 1 remain parallel and symmetrical, the soft gripping device is multi-layer double-wound. When the elastic fitting structure 3 and the driving body 1 are at a specific inclination angle, the soft gripping device is single-layer multi-turn winding.

[0036] The gripping mode is available in single-branch mode or dual-branch collaborative mode. The single-branch mode allows for the grasping of light and irregular objects, while the dual-branch collaborative mode uses two flexible gripping devices symmetrically arranged on the same bracket to grasp large loads. Under a driving air pressure of 0.1-0.2MPa, the driver body 1 adaptively grasps objects with a diameter of 20mm to 130mm, with a load capacity of 800N.

[0037] like Figure 3 As shown, the inner layer is designed with different friction coefficients of the inner and outer layer materials. , outer layer low , effectively optimize the self-locking performance of CWG and improve its engineering applicability, This is the angle at which the second clamping jaw 8 does not contact the object to be clamped due to the thickness of the soft gripping device. Since this angle is small, it is ignored in the theoretical model.

[0038] like Figure 4As shown, the soft grasping device of the present invention was tested on grasping objects of different shapes and weights. The soft grasping device was fixed on a robotic arm, and the stretching and winding of the soft grasping device were achieved by pressurizing or decompressing. From the experimental results, within the test range, for objects to be clamped with a mass of less than 300g and a maximum inscribed circle diameter between 25mm and 120mm, the soft grasping device was able to complete the grasping task and exhibit good morphological adaptability. For non-cylindrical objects, after the initial grasping, air pressure is continuously applied to the end pneumatic unit 2 to enhance the contact between the end of the soft grasping device and the object to be clamped, thereby achieving better grasping stability. Even when subject to certain external force interference, it is difficult for the object to be clamped to escape from the grasp of the soft grasping device. Therefore, the soft grasping device has high adaptability in scenarios involving small, lightweight and geometrically diverse objects.

[0039] like Figure 5 As shown, the soft gripping device of the present invention is subjected to a load force test in a self-locking state. When a single soft gripping device is used to perform a heavy object grasping test, the object will generate a rotational torque, which may affect the experimental results. Therefore, when testing the friction self-locking effect, the soft gripping device is fixed to the bracket to reduce the interference of the rotational torque on the results. In the specific implementation process, the soft gripping device is first wrapped around a fixed beam, and the weight hanging below is gradually increased. The experimental results show that when the load increases from 1kg to 31kg, the suspension point moves downward. However, when observed from the side, the part wrapped by the soft gripping device did not slide, proving that the soft gripping device maintains strong gripping stability under high loads.

[0040] like Figures 6 to 9 As shown, the soft grasping device of the present invention was subjected to a grasping comparison test in a single-branch mode and a double-branch cooperative mode, as well as a load test in a double-branch cooperative mode. When a single soft grasping device is used to grasp a heavier object, the effect of the soft grasping device may be affected because the object may rotate. This is because when the object is heavy or the grasping force is insufficient, a single soft grasping device may not be able to provide sufficient anti-rotation torque, causing the object to rotate, thereby affecting the stability and safety of the grasping. In order to solve this problem, two symmetrically arranged and collaboratively working soft grasping devices are configured. The synergistic effect of the double-branch soft grasping device effectively suppresses the rotation tendency of the object, provides a more balanced grasping force, and ensures the stability and reliability of the grasping process.

[0041] In order to verify the effectiveness of the collaboration of the two-branch soft grasping device and conduct a load test, a dumbbell was selected as the test object in the experiment. First, a single soft grasping device was tested. When grasping the dumbbell, due to its mass and shape characteristics, the object rotated and could not be successfully lifted. This phenomenon shows that a single soft grasping device cannot effectively cope with the rotation of the object, which limits its application in certain scenarios. Next, the two soft grasping devices were symmetrically arranged and fixed at the end of the robotic arm, and the dumbbell grasping experiment was carried out again. The synergistic effect of the two-branch soft grasping device significantly improved the grasping stability, prevented the rotation of the dumbbell, and successfully completed the grasping and lifting tasks. This shows that the symmetrical arrangement of the two-branch soft grasping device effectively suppresses the rotation of the object, making the grasping process more stable and reliable.

[0042] To further test the performance of the dual-branch soft gripper, load tests were conducted using both a robotic arm and a fixed bracket. The dual-branch soft gripper not only prevents rotation of the object but also enables more stable grasping under varying load conditions, demonstrating greater grasping stability and load-bearing capacity compared to a single soft gripper.

[0043] The friction-locking, adaptive wrapping soft gripping control method and gripping device of this invention utilizes a combination of a friction-locking structure and a flexible wrapping strategy. Under specific conditions, friction-locking is triggered by structural deformation, limiting load capacity directly to material strength rather than drive energy. Pre-expansion and adaptive wrapping allow for flexible conformance to objects of varying sizes, while achieving stable locking for vertical gripping in a dual-branch collaborative mode.

[0044] The above embodiments are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A friction self-locking adaptive winding soft body grasping control method, characterized in that: It includes: A quantitative mapping model of biomimetic winding mechanics and frictional self-locking structures was established. Based on the coupling of the soft body's winding spiral configuration and continuous contact force, the design parameters of the driving body and the elastically fitted structure under both expansion and contraction were determined. Adaptive fitting and local pressurization are coordinated and controlled. The second clamping jaw is driven to spirally wind by deflating the main body and contracting the elastic fitting structure. The winding curvature of the second clamping jaw is adjusted synchronously. The elastic fitting structure adaptively fits the surface contour of the object to be clamped. The end pneumatic unit performs local pressurization after winding to fix the object to be clamped. Based on the soft body spiral winding dynamics and soft body structural deformation, the friction coefficient between each gripper and the object to be clamped is established With winding angle The contact force friction model is used to obtain the force balance equation of friction force T and load force F under multi-turn winding: ； Where, is the friction coefficient between the second clamping jaw and the object to be clamped, is the friction coefficient between the first and second jaws, is the winding angle between the second clamping jaw and the object to be clamped, , is the thickness error angle of the second jaw; The critical condition of friction self-locking of the soft gripping device is obtained through the force balance equation: <360°、 By optimizing the friction coefficient and design parameters, the operating space and load force are coordinated and optimized, and the soft gripping device is controlled to adaptively fit and grasp the object to be clamped.

2. The friction self-locking adaptive winding soft body grasping control method according to claim 1, characterized in that: The quantitative mapping model of bionic winding mechanics and friction self-locking structure is: ； Where, is the tension on the second clamp in the i-th winding segment, is the force at the starting point of the i-th winding segment of the second clamping jaw, The tension on the second clamp in the i+1 winding segment, is the friction coefficient between the i+1th winding segment and the ith winding segment between the second clamping jaw and the object to be clamped.

3. The friction self-locking adaptive winding soft body grasping control method according to claim 1, characterized in that: Based on the parameter relationship between the driving body and the elastic fitting structure, the design parameters of the elastic fitting structure are obtained, specifically: ； Where P is the air pressure of the driving body, r is the radius of the driving body after expansion, l1 is the length of the driving body, l2 is the initial length of the elastic fitting structure, and k is the elastic coefficient of the elastic fitting structure.

4. The friction self-locking adaptive winding soft body grasping control method according to claim 1, characterized in that: The winding angle θ of the soft gripping device under multi-turn winding min for: 。 5. The friction self-locking adaptive winding soft body grasping control method according to claim 1, characterized in that: The force balance equation within each winding segment in the soft grasping device is: ； ； Where C0 is a constant term.

6. A friction self-locking adaptive winding soft gripping device, characterized by: It includes a driving body, an end pneumatic unit, an elastic fitting structure, a first clamp and a second clamp. The elastic fitting structure is arranged on the first end face of the driving body. The outer surfaces of the driving body and the elastic fitting structure are wrapped with multiple annular parts. The end pneumatic unit is connected to the second end face of the driving body. The first clamp and the second clamp are symmetrically arranged on both sides of the driving body. The driving body, the end pneumatic unit, the elastic fitting structure and the annular part are arranged between the first clamp and the second clamp. Based on the driving body-elastic fitting structure coupling driving characteristics, active control of the spiral motion form is achieved by adjusting the internal air pressure of the driving body.

7. The friction self-locking adaptive winding soft gripping device according to claim 6, characterized in that: The length of the drive body is 850~900mm, and the length of the end pneumatic unit is 80~120mm.

8. The friction self-locking adaptive winding soft gripping device according to claim 6, characterized in that: The length and width of the first clamping jaw and the second clamping jaw are both greater than the length and width of the driving body.

9. The friction self-locking adaptive winding soft gripping device according to claim 6, characterized in that: The driving body and the terminal pneumatic unit are both double-layer pneumatic drive structures.

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