Rotary driving type flexible weaving self-adaptive end effector and grabbing method

Abstract

The invention relates to a rotary driving type flexible weaving self-adaptive end effector and a grabbing method, and belongs to the technical field of robot end effects.The rotary driving type flexible weaving self-adaptive end effector comprises a fixed disc and a rotary disc which are coaxially arranged, and the rotary disc is configured to be controlled to rotate relative to the fixed disc; the multiple sets of flexible strips are evenly distributed in the circumferential direction of the fixed disc and the rotating disc, each set of flexible strips comprises at least two flexible strips which are arranged in an overlapped mode, and after the flexible strips are pre-twisted in the long axis direction of the flexible strips according to a preset angle, the two ends of the flexible strips in each set of flexible strips are aligned respectively; wherein one end is defined as a fixed end to be connected with the fixed disc, and the other end is defined as a movable end to be connected with the rotating disc; and when the manipulator is controlled to rotate along with the rotating disc, the movable ends of all the flexible strips are dragged to synchronously do circular motion, centripetal enveloping grabbing operation or lateral winding grabbing operation is executed in a self-adaptive mode based on objects to be grabbed, and the manipulator has natural adaptability to the objects of different geometrical shapes and has the extremely high load self-weight ratio.

Description

Technical Field

[0001] This invention relates to the field of robot end effector technology, specifically to a rotary-driven flexible weaving adaptive end effector and a gripping method. Background Technology

[0002] Existing robotic end effectors are mainly divided into two categories: rigid grippers and flexible grippers. Rigid grippers are typically composed of metal or hard plastic fingers driven by motors or pneumatics. However, they require complex multi-degree-of-freedom control and force sensing systems to achieve stable gripping of irregularly shaped objects, and are prone to surface damage to objects (especially fruits, precision parts, etc.) due to improper gripping force control. In addition, their complex structure and large weight result in low load-weight ratio and poor energy utilization efficiency. Existing flexible grippers, such as pneumatic soft grippers and universal grippers based on particle blockage, etc., typically require a pump and valve system, are bulky, have slow response speed, and limited gripping force. While particle blockage grippers can adaptively envelop, they usually cannot achieve "entanglement" gripping. The lateral gripping method may leave particulate material after releasing the object, making it unsuitable for clean environments. In addition, existing gripping devices using variable stiffness flexible structures, such as Chinese patent CN121316000A, disclose a variable stiffness flexible space debris gripping device based on a braided structure, including a gripping component, a connecting component, a driving device, a power supply module, and a control component. The driving device is used to drive the upper fixer to rotate, thereby driving multiple flexible braided strips to retract or unfold, achieving adaptive conformal capture of space debris of different shapes. However, it has the following disadvantages: (1) Slow response speed and poor controllability. The thermal deformation response of the shape memory alloy it relies on has hysteresis, and the stiffness adjustment range is limited, making it difficult to achieve fast and accurate gripping action. (2) It requires independent heating and control circuits, making the system complex and requiring continuous energy input to maintain the gripping state, resulting in low energy efficiency. (3) Weak environmental adaptability. The reliability of the active control element is reduced in impact, vibration, or pollution environments. Therefore, a rotary-driven flexible braided adaptive end effector and gripping method are urgently needed to solve the above problems. Summary of the Invention

[0003] The purpose of this invention is to provide a rotary-driven flexible braided adaptive end effector and gripping method to solve the problems mentioned in the background art, and to be applicable to scenarios of non-destructive, high-load gripping of irregularly shaped and easily damaged objects.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a rotary-driven flexible braiding adaptive end effector, comprising: A fixed disk and a rotating disk are coaxially arranged, the rotating disk being configured to rotate in a controlled manner relative to the fixed disk; Several groups of flexible strips are evenly distributed circumferentially along a fixed disk and a rotating disk. Each group of flexible strips includes at least two overlapping flexible strips. After each flexible strip is pre-twisted around its long axis at a preset angle, the two ends of each flexible strip in each group are aligned, with one end defined as the fixed end connected to the fixed disk and the other end defined as the movable end connected to the rotating disk. As the rotating disk rotates in a controlled manner, the moving ends of all the flexible strips move in a circular motion in sync, causing each group of flexible strips to converge and weave towards the center, creating a dynamically changing central cavity. Based on the object to be grasped, the system adaptively performs a centripetal envelope grasping operation or a lateral wrapping grasping operation.

[0005] Preferably, the diameter of the rotating disk is smaller than the diameter of the fixed disk, and the ratio of the diameter of the rotating disk to the diameter of the fixed disk is 0.5 to 1. Within this range, an ideal weaving effect can be achieved.

[0006] Preferably, the flexible strips in each group are pre-twisted around their long axis at a preset angle of 160° to 200°.

[0007] Preferably, each group of flexible strips is pre-twisted around its long axis at a preset angle of 180°.

[0008] Preferably, the fixed ends of each group of flexible strips are sequentially locked and fixed to the fixed disk by a first fastener, and the movable ends of each group of flexible strips are sequentially locked and fixed to the rotating disk by a second fastener.

[0009] Preferably, each group of flexible strips includes at least two flexible strips of different lengths that are stacked together, and the length of the outer flexible strip is greater than the length of the inner flexible strip.

[0010] Preferably, after each group of flexible strips is pre-twisted, gaps are reserved between each flexible strip in each group of flexible strips, and multiple groups of strips are in a non-contact state.

[0011] Preferably, the cross-sectional geometry of each flexible strip is elongated, and the aspect ratio is in the range of 3 to 70.

[0012] Preferably, each of the flexible strips is a component of a PET material.

[0013] This invention also discloses a rotary-driven flexible knitting adaptive gripping method, which utilizes an end effector for gripping operations, specifically including: S1, Drive Rotation: Drives the rotating disk to rotate about the axis relative to the fixed disk; S2, Passive Interweaving: As the rotating disk rotates, the moving ends of all the flexible strips are pulled to make circular motions in sync, so that each group of flexible strips passively bends in space during the motion and naturally collides, crosses and intertwines with other groups of flexible strips. S3. Formation of the braided state: The continuous rotation of the rotating disk deepens the interweaving between the flexible strips, eventually forming a braided structure with a central cavity that can be dynamically changed in a controlled manner. S4: Adaptive crawling, including: Envelope mode: When the target object is directly below the actuator, the control disk rotates in the forward direction, the central cavity of the woven structure contracts, and each set of flexible strips uniformly envelops the surface of the object, performing a centripetal envelope grasping operation. Entangling mode: When the target object is a long rod and located to the side of the actuator, the control disk rotates and drives the woven structure to laterally adhere to and wrap around the side of the target object, performing a lateral entangling gripping operation.

[0014] Beneficial effects: The actuator of this invention abandons active control components such as shape memory alloys and relies entirely on mechanical structure and material properties to achieve grasping; it has no complex circuits and thermal management problems, and has extremely strong anti-interference and pollution resistance capabilities, making it suitable for harsh environments such as agriculture and warehousing; moreover, it can naturally generate two grasping modes through the same rotation drive, realizing multiple uses of one device, and has a natural adaptability to objects with different geometric shapes.

[0015] The actuator of this invention has an extremely high load-to-weight ratio. By utilizing the enhanced frictional coupling effect generated by the multi-layer composite flexible strip and the huge envelope area provided by the woven structure, it achieves an ultra-large load under extremely light weight. Its load-to-weight ratio can exceed 3000, far exceeding that of traditional rigid or pneumatic grippers. Moreover, the flexible strip is in surface contact with the object, and the pressure distribution is uniform, which fundamentally avoids damage to fragile objects such as fruits, vegetables, and precision workpieces. Attached Figure Description

[0016] Figure 1 This is an exploded view of the rotary-driven flexible braided adaptive end effector of the present invention; Figure 2 A schematic diagram of the structure of the fixed disk and rotating disk coaxially arranged in this invention; Figure 3 This is a schematic diagram illustrating the fabrication and installation of each group of flexible strips in this invention; Figure 4 This is a schematic diagram of the interlacing of various groups of flexible strips in this invention; Figure 5 This is a flowchart illustrating how the present invention drives the various groups of flexible strips to form a woven structure. Figure 6 This is a schematic diagram showing two working modes of the actuator of the present invention; Figure 7 A physical image of the actuator of this invention performing a centripetal envelope grasping operation; Figure 8 This is a physical image of the actuator of the present invention performing a lateral winding and gripping operation.

[0017] Labels in the diagram: 1. Fixed disk; 1a. First V-groove; 1b. First threaded hole; 2. Rotating disk; 2a. Second V-groove; 2b. Second threaded hole; 3. Flexible strip; 3a. First flexible strip; 3a ， 1. Second flexible strip; 3b ， 1. First mounting through hole; 3b. Second mounting through hole; 4. First pressure plate; 5. First fastener; 6. Second pressure plate; 7. Second fastener; 8. Spherical object; 9. Elongated object. Detailed Implementation

[0018] To make the objectives and advantages of this invention clearer, the invention will be specifically described below with reference to embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of the invention and does not strictly limit the scope of protection specifically claimed by the invention.

[0019] Example: Reference Figure 1 As shown, a rotary-driven flexible braided adaptive end effector includes a fixed disk 1 and a rotating disk 2 coaxially arranged, and several sets of flexible strips 3 evenly distributed circumferentially along the fixed disk 1 and the rotating disk 2. The rotating disk 2 is configured to rotate in a controlled manner relative to the fixed disk 1. In this embodiment, a base with a driver is used as the driving source. Figures 1-2 As shown, the fixed disk 1 is fixedly installed on the base. The rotating disk 2 and the fixed disk 1 can rotate coaxially relative to each other through a deep groove ball bearing. The rotating disk 2 is connected to the output shaft of the driver (such as a servo motor) through a coupling. The driver drives the rotating disk 2 to rotate relative to the fixed disk 1 around their common axis.

[0020] The diameter of the rotating disk 2 is smaller than the diameter of the fixed disk 1. In one embodiment, the ratio of the diameter of the rotating disk 2 to the diameter of the fixed disk 1 is 0.5 to 1; within this range, an ideal weaving effect can be produced.

[0021] In this embodiment, each group of flexible strips 3 includes at least two overlapping flexible strips 3. The multi-layer design can significantly enhance the density, stability, and gripping force of the final woven structure through interlayer friction and coupling effects without significantly increasing the driving load. After each group of flexible strips 3 is pre-twisted around its long axis at a preset angle of 160° to 200°, the two ends of each flexible strip 3 in each group are aligned. One end is defined as the fixed end connected to the fixed disk 1, and the other end is defined as the movable end connected to the rotating disk 2. This pre-twisting makes the flexible strip 3 present a spatial spiral shape with a constant helical curvature when it is not subjected to external force. When its end is rotated and pulled, this inherent curvature causes the flexible strip 3 to deviate from the plane formed by its connection point, resulting in three-dimensional warping. This causes it to cross and entwine with other flexible strips 3 with the same pre-twisting direction in a non-parallel and orderly manner. This process does not require external active control of the shape of the flexible strips.

[0022] In one embodiment, each group of flexible strips includes at least two flexible strips 3 of different lengths that are stacked together, and the length of the outer flexible strip is greater than the length of the inner flexible strip.

[0023] After each group of flexible strips 3 is pre-twisted, gaps are reserved between the flexible strips within each group, and multiple groups of strips are in a non-contact state. The length of the multi-layer strips is set with the following requirements: the outer flexible strip is the longest, and the length of the inner flexible strip decreases sequentially. Specifically, after the flexible strip combination is reverse-twisted, gaps still need to be left between the inner and outer flexible strips (e.g., Figure 3 As shown), multiple sets of flexible strips should maintain a gap rather than contact; the geometric shape of the flexible strip cross section is long strip; in one embodiment, the aspect ratio of the flexible strip cross section is in the range of 3 to 70. This range allows the strip structure to have the in-plane buckling mechanical properties of a plate and shell structure. This property allows the strip group structure to maintain its geometric shape and be stably woven while achieving extreme lightweighting, and to realize the large load ratio.

[0024] In one embodiment, reference Figure 3 As shown, the flexible strip is made of PET (polyethylene terephthalate) film and is formed by laser cutting. It completely eliminates active control components such as shape memory alloys and relies entirely on mechanical structure and material properties to achieve gripping. Before installation, each cut PET flexible strip is manually or by tooling pre-twisted about 180°. The fixed end is locked and fixed to the fixed plate 1 by the first fastener 5 in sequence, and the movable end of each group of flexible strips is locked and fixed to the rotating plate 2 by the second fastener 7 in sequence.

[0025] In one embodiment, reference Figures 1-2As shown, the fixed disk 1 has eight first V-grooves 1a and corresponding first threaded holes 1b evenly distributed around its circumference; the rotating disk 2 has eight second V-grooves 2a and corresponding second threaded holes 2b. Each set of flexible strips 3 includes two flexible strips of different lengths that are stacked together, which are defined as the first flexible strip 3a and the second flexible strip 3a, respectively. ， First flexible strip 3a and second flexible strip 3a ， The fixed end and the movable end are respectively provided with a first mounting through hole 3b ， The second mounting through hole 3b; the fixed ends of each set of flexible strips 3 are fixed to the fixing plate 1 by the first pressure plate 4 and the first fastener 5 (such as screws); during installation, the first fastener 5 passes through the through hole of the first pressure plate 4 and the first mounting through hole 3b of the fixed end of the flexible strip in sequence. ， Finally, the flexible strip is screwed into the first threaded hole 1b of the fixed plate, pressing the end of the flexible strip into the first V-groove 1a. When installing each set of flexible strips, the movable end is installed on the rotating plate 2 through the second pressure plate 6 and the second fastener 7 (such as a screw). The second fastener 7 passes through the through hole on the second pressure plate and the second mounting through hole 3b of the movable end of the flexible strip in sequence, and finally screws into the second threaded hole 2b of the rotating plate 2, thereby pressing and fixing the end of the flexible strip into the second V-groove 2a.

[0026] During operation, as the rotating disk 2 rotates in a controlled manner, the moving ends of all flexible strips are pulled to make circular motions in sync, causing each group of flexible strips to converge and weave towards the center, creating a dynamically changing central cavity, and adaptively performing centripetal envelope gripping or lateral wrapping gripping operations based on the item to be gripped.

[0027] refer to Figures 4-8 As shown, a rotary-driven flexible knitting adaptive gripping method is provided, which uses the aforementioned actuator to perform gripping operations, specifically including: Preparation phase: The actuator is positioned above or to the side of the target object, and each set of flexible strips 3 is in a naturally drooping state; Drive and interweaving phase (corresponding to Figure 4 , Figure 5 ): Start the servo motor to drive the rotating disk 2 to rotate at a constant speed (such as 10-30 rpm); the moving ends of each group of flexible strips 3 move accordingly. Due to the pre-twisting, the flexible strips 3 quickly break away from the parallel state, undergo three-dimensional bending in space and come into contact with each other. The woven state formation stage: After rotating about 90-180 degrees, the three flexible strips are fully interwoven, forming a tight "woven net" or "woven cage" structure in the top center area, which is the woven state; this process is completely passive and does not require sensor feedback or active shape control.

[0028] The adaptive crawling phase includes two modes: Envelope pattern, such as Figure 6 and Figure 7 When the target object is directly below the actuator, taking spherical object 8 as an example, the control disk rotates in the positive direction (the direction of strip twisting), the central cavity of the woven structure contracts, and each group of flexible strips evenly envelops the surface of the object, performing a centripetal enveloping gripping operation, so that it does not slip or cause damage when lifted.

[0029] Winding pattern, see reference Figure 6 and Figure 8 When the target object is a long rod and located to the side of the actuator, taking the long object 9 as an example, the rotating disk is controlled to rotate and drive, and the woven structure is laterally attached to and wrapped around the side of the target object to perform a lateral wrapping gripping operation and achieve stable gripping.

[0030] This application also provides a specific experiment to comprehensively analyze the effectiveness and superiority of the methods provided above; the settings are as follows: Make a prototype and test it: Prototype parameters: The actuator structure of the above embodiment is adopted, with 8 sets of flexible strips, and the flexible strips are made of PET material.

[0031] Test 1 (single-layer flexible strip): The weight of a single flexible strip is 3.2g; during the test, it stably grips and lifts a 10kg standard weight, and the load-to-weight ratio is approximately 10000g / 3.2g = 3125.

[0032] Test 2 (Multi-layer Flexible Strips): Two flexible strips of 40mm and 30mm lengths were used in combination. Each set weighed approximately 0.7g, and the total weight of 8 sets was 5.6g. In the test, a 22kg weight was stably gripped and lifted. The load-to-weight ratio was approximately 22000g / 5.6g ≈ 3928.

[0033] Comparative results: This performance index is significantly better than that of traditional two-finger grippers (the load-to-weight ratio is usually <100) and the active braided grippers mentioned in the background technology, which verifies the significant contribution of key feature B (multi-layer composite design) to improving gripping force.

[0034] The embodiments of the present invention have been described in detail above with reference to the examples. However, the present invention is not limited to the above embodiments. For those skilled in the art, after learning the contents described in the present invention, several equivalent changes and substitutions can be made without departing from the principle of the present invention. These equivalent changes and substitutions should also be considered to fall within the protection scope of the present invention.

Claims

1. A rotary-driven flexible braided adaptive end effector, characterized in that: include: A fixed disk and a rotating disk are coaxially arranged, the rotating disk being configured to rotate in a controlled manner relative to the fixed disk; Several groups of flexible strips are evenly distributed circumferentially along a fixed disk and a rotating disk. Each group of flexible strips includes at least two overlapping flexible strips. After each flexible strip is pre-twisted around its long axis at a preset angle, the two ends of each flexible strip in each group are aligned, with one end defined as the fixed end connected to the fixed disk and the other end defined as the movable end connected to the rotating disk. As the rotating disk rotates in a controlled manner, the moving ends of all the flexible strips move in a circular motion in sync, causing each group of flexible strips to converge and weave towards the center, creating a dynamically changing central cavity. Based on the object to be grasped, the system adaptively performs a centripetal envelope grasping operation or a lateral wrapping grasping operation.

2. The rotary-driven flexible braided adaptive end effector according to claim 1, characterized in that: The diameter of the rotating disk is smaller than that of the fixed disk, and the ratio of the diameter of the rotating disk to that of the fixed disk is 0.5 to 1.

3. The rotary-driven flexible braided adaptive end effector according to claim 2, characterized in that: Each group of flexible strips is pre-twisted around its long axis at a preset angle of 160° to 200°.

4. The rotary-driven flexible braided adaptive end effector according to claim 3, characterized in that: Each group of flexible strips is pre-twisted around its long axis at a preset angle of 180°.

5. A rotary-driven flexible braided adaptive end effector according to claim 1, characterized in that: The fixed ends of each group of flexible strips are sequentially locked and fixed to the fixed disk by the first fastener, and the movable ends of each group of flexible strips are sequentially locked and fixed to the rotating disk by the second fastener.

6. A rotary-driven flexible braided adaptive end effector according to claim 2, characterized in that: Each set of flexible strips includes at least two flexible strips of different lengths that are stacked together, with the outer flexible strip being longer than the inner flexible strip.

7. A rotary-driven flexible braided adaptive end effector according to claim 6, characterized in that: After each group of flexible strips is pre-twisted, gaps are reserved between the flexible strips in each group, and multiple groups of strips are in a non-contact state.

8. A rotary-driven flexible braided adaptive end effector according to claim 7, characterized in that: The cross-section of each of the aforementioned flexible strips has a long strip shape, and the aspect ratio ranges from 3 to 70.

9. A rotary-driven flexible braided adaptive end effector according to claim 7, characterized in that: Each of the aforementioned flexible strips is a component made of PET material.

10. A rotary-driven flexible knitting adaptive gripping method, characterized in that: The gripping operation using a rotary-driven flexible braided adaptive end effector according to any one of claims 1-9 specifically includes: S1, Drive Rotation: Drives the rotating disk to rotate about the axis relative to the fixed disk; S2, Passive Interweaving: As the rotating disk rotates, the moving ends of all the flexible strips are pulled to make circular motions in sync, so that each group of flexible strips passively bends in space during the motion and naturally collides, crosses and intertwines with other groups of flexible strips. S3. Formation of the braided state: The continuous rotation of the rotating disk deepens the interweaving between the flexible strips, eventually forming a braided structure with a central cavity that can be dynamically changed in a controlled manner. S4: Adaptive crawling, including: Envelope mode: When the target object is directly below the actuator, the control disk rotates in the forward direction, the central cavity of the woven structure contracts, and each set of flexible strips uniformly envelops the surface of the object, performing a centripetal envelope grasping operation. Entangling mode: When the target object is a long rod and located to the side of the actuator, the control disk rotates and drives the woven structure to laterally adhere to and wrap around the side of the target object, performing a lateral entangling gripping operation.

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