Tendon-driven flexible gripper based on miura-ori folding design

Abstract

The application discloses a tendon-driven flexible gripper based on Miura plate folding design, which comprises a driving input module, a fixed bearing platform, a sliding platform and a Miura plate base. The driving input module is composed of a rotating disc and a transmission rope system. The rotating disc is used to drive the transmission rope system to move, and the transmission rope system is designed in a closed path. The clockwise and counterclockwise rotation of the rotating disc will respectively cause the transmission rope system to retreat and advance. The transmission rope system is connected with the sliding platform, and the two ends of the Miura plate base are respectively connected with the fixed bearing platform and the sliding platform. When the rotating disc rotates, the Miura plate base is folded or unfolded along the preset crease line, so that the state of the Miura plate base changes between clamping and flat unfolding. The soft gripper of the application is driven and controlled by a single steering engine to realize the opening and closing movement of the gripper, and the equipment quality and the driving control complexity are significantly reduced.

Description

Technical Field

[0001] This invention belongs to the field of soft robot design, specifically relating to a tendon-driven flexible gripper based on the Miura sheet folding design. Background Technology

[0002] Robots used in traditional industrial, agricultural, medical, and other applications are typically composed of rigid components. However, rigid robots have poor adaptability to their working environment, making them difficult to operate in diverse settings. Furthermore, the operation of rigid robots inevitably presents safety hazards, potentially causing harm to operators and the target object. In response to these drawbacks of rigid robots, soft robots, with their inherent high environmental adaptability and user-friendly human-robot interaction, have attracted increasing research and industrial attention.

[0003] Origami is an ancient art of paper folding, referring to the process of constructing spatial structures using only folds and bends on a whole sheet of paper. Recent advances in origami technology have led to a significant leap forward in the field of foldable structures. Typical folding research aims to facilitate the storage and transportation of large structures, but by designing structures to fold and deform along predetermined shapes, unconventional static properties can be acquired, such as multimodal behavior, adjustable stiffness, and negative Poisson's ratio. Origami robots are a type of robot that achieves form and function through folding; they utilize crease design to achieve changes in form and function during unfolding. This close integration of origami and robotics has become a new direction in the development of origami and an important branch of flexible robotics research.

[0004] To address the problem of map folding, K. Miura proposed the Miura origami structure in 1985. (Miura, K. (1985). Method of Packaging and Deployment of Large Membranes in Space.) The Miura origami structure is a basic rigid planar foldable structure that has been widely used in architectural and engineering design in recent years. Each basic unit of the Miura origami structure consists of four creases intersecting at a vertex, with two creases located on the center line of the unit and the other two creases symmetrically distributed at acute angles to the horizontal creases.

[0005] Previous origami-based grippers often involved complex fold designs and structural fits to achieve their gripping function, significantly reducing their adaptability to complex environments and scenarios. Furthermore, the gripper body was mostly made of chemically cured materials such as silicone, resulting in a long manufacturing cycle. These drawbacks severely limited the application of origami-based grippers. Summary of the Invention

[0006] To address the problems in existing technologies, this invention proposes a tendon-driven flexible gripper based on the Miura sheet folding design. The fold design of this invention simplifies processing, and the gripper body is made from readily available sheet materials. Due to the foldability and unique mechanical properties of the origami structure, a tendon-driven approach can be used to create a soft gripper with compliant grasping capabilities. The soft gripper of this invention is controlled by a single servo motor, significantly reducing equipment weight and drive control complexity. Furthermore, the rope arrangement of this invention effectively converts the rotational motion output by the motor into the parallel movement of the sliding table, further facilitating the conversion of tension and pressure into the opening and closing motion of the soft gripper through the origami structure.

[0007] The tendon-driven flexible gripper based on the Miura sheet folding design of the present invention includes: a drive input module, a fixed bearing platform, a sliding platform, and a Miura sheet substrate;

[0008] The drive input module includes a turntable and a transmission rope system driven by the turntable. The transmission rope system is designed as a closed path. The turntable is mounted on the fixed support platform and is used to receive external power input and drive the transmission rope system to move.

[0009] The fixed bearing platform is provided with a guide rail, and the sliding platform is slidably mounted on the guide rail. The sliding platform is fixedly connected to the transmission rope system so as to move synchronously with the transmission rope system.

[0010] When fully unfolded, the Miura sheet substrate has a rectangular main body. A rectangular fixing part extends outward from the center of each of the two long sides of the main body. One rectangular fixing part is fixed to the sliding platform, and the other is fixed to the fixed support platform. When the sliding platform moves to one end of the guide rail, the Miura sheet substrate is fully unfolded. When the sliding platform moves to the other end of the guide rail, the Miura sheet substrate folds along a preset crease line and forms a gripping state.

[0011] The main body has a long side length a = 2l and a short side length The length of the long side of the rectangular fixed part is c = b / 2, and the length of the short side is d = c / 3. The long side of the rectangular fixed part coincides with the long side of the main body. Let A be the two endpoints of the long side of the coinciding part. The distance from point A on the long side of the main body towards the short side is... Select point P4;

[0012] Let O be the center point of the main body, and B be the intersection of the median of the shorter side of the main body and the shorter side; the distance from point O on the line OB is... Points P1, P2, and P3 are selected respectively at the locations;

[0013] The crease lines on the left and right sides of the main body are completely symmetrical, and the crease lines on the top and bottom sides are completely symmetrical. Among them, points A and P1 on the same side are connected by a mountain crease line, points A and P2 are connected by a valley crease line, points P4 and P3 are connected by a mountain crease line, points O and P1 are connected by a valley crease line, points P1 and P2 are connected by a mountain crease line, points P2 and P3 are connected by a valley crease line, and points P3 and B are connected by a mountain crease line.

[0014] As a preferred embodiment of the present invention, the rectangular fixing part has a circular hole with a diameter of c / 10 at a distance c / 10 from the edge of the two short sides along the center line of the short side. The circular holes are used to connect the sliding platform or the fixed bearing platform.

[0015] As a preferred embodiment of the present invention, the turntable is provided with a fitting groove on its circumference, and the transmission rope is partially disposed in the fitting groove of the turntable. The clockwise and counterclockwise rotation of the turntable will respectively cause the transmission rope to drive the sliding platform to move backward and forward on the slide rail.

[0016] As a preferred embodiment of the present invention, the fixed bearing platform includes a fixed end, a guide rail, and a remote closed end; the fixed end and the remote closed end are located at both ends of the guide rail, and the fixed bearing platform is fixedly connected to a rectangular fixed part of the Miura sheet substrate through the fixed end; both the remote closed end and the fixed end have through holes for the transmission rope to pass through.

[0017] As a preferred embodiment of the present invention, the guide rail is composed of two parallel guide plates, and the sliding platform is disposed between the two guide plates; the distal end of the closed end is designed with a groove corresponding to the cross-sectional shape of the two guide plates, and the distal end of the closed end is fitted with the guide plate through the groove to prevent the sliding platform from sliding off the rail.

[0018] As a preferred embodiment of the present invention, the sliding platform has a groove corresponding to the shape of the guide rail, and the power transmitted by the transmission rope system slides on the guide rail; the middle part of the sliding platform has a through hole for arranging the transmission rope system, and the transmission rope system passes through the through hole and is fixedly connected to the sliding platform.

[0019] As a preferred embodiment of the present invention, the material of the Miura sheet substrate is ordinary cardboard material / plastic sheet material with high flexibility, such as polypropylene (PP) sheet, polyethylene (PE) sheet, TPU sheet, PET sheet, etc. / metal sheet material with strong flexibility, such as aluminum alloy sheet, brass sheet, etc.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) This invention adopts a folding design based on sheet metal. Its core lies in using a panel material with a certain rigidity for structural construction. The corresponding folding design allows for flexible and precise control of the overall deformation. Through the designed folding mode, various parameters such as the opening and closing degree of the flexible gripper and the gripping force can be adjusted according to the needs of the actual application scenario, thereby achieving the ideal gripping effect. Through the folding design based on sheet metal, a certain degree of flexibility is retained to adapt to the gripping of various objects, while good rigidity is maintained to maintain a stable gripping posture, significantly improving the adaptability and accuracy of the gripper in complex tasks.

[0022] (2) The Miura-based crease line design used in this invention allows the flexible gripper, composed of panels with a certain rigidity, to smoothly transition from an initial parallel unfolded state to a closed clamping state. During this process, the flexible gripper continuously changes shape in a highly controllable manner, thus applying appropriate clamping force in any intermediate state, thereby maintaining good contact and control over the target object.

[0023] (3) The Miura-based crease line design used in this invention fully utilizes simple and efficient geometric principles, achieving complex spatial folding and unfolding functions through a limited number of crease lines, all of which are straight paths. Compared to curved crease designs, the crease line design used in this invention can greatly simplify the manufacturing process while ensuring structural stability and controllable deformation.

[0024] (4) The material used in the Miura board substrate of the present invention is common and readily available materials such as ordinary cardboard or plastic board and metal sheet with high flexibility. It can achieve efficient space unfolding and compact folding functions, and can also ensure that it maintains a stable shape during folding and unfolding, and can withstand a certain load.

[0025] (5) The rope drive used in this invention effectively converts the rotational motion generated by the motor into the linear parallel movement of the slide, realizing power transmission and motion conversion. When the motor drive shaft rotates, it drives the rope to be wound and released in an orderly and stable manner, thereby pulling the slide along the guide rail to perform precise and stable translational motion. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the flexible gripper (unfolded) of the present invention;

[0027] Figure 2 This is a schematic diagram of the flexible gripper (closed) of the present invention;

[0028] Figure 3 This is a schematic diagram of the structure of the turntable of the present invention;

[0029] Figure 4This is a schematic diagram of the fixed end and guide rail of the fixed bearing platform of the present invention;

[0030] Figure 5 This is a schematic diagram of the far-end closed section of the fixed bearing platform of the present invention;

[0031] Figure 6 This is a schematic diagram of the sliding platform of the present invention;

[0032] Figure 7 This is a schematic diagram of the Miura sheet substrate of the present invention. The solid lines are mountain fold lines and the dashed lines are valley fold lines.

[0033] Figure 8 This is a schematic diagram of the flexible gripper of the present invention holding an object;

[0034] Figure 9 This is a schematic diagram of the gripping area during the unfolding and closing process of the flexible gripper of the present invention.

[0035] Figure 10 This is a schematic diagram showing the relationship between the distance at the end of the flexible gripper of the present invention and the degree of folding;

[0036] Figure 11 This is a schematic diagram comparing the gripping force of the flexible gripper of the present invention with that of other origami grippers, showing a specific example of the gripper. Detailed Implementation

[0037] The present invention will be further described and illustrated below with reference to specific embodiments. The embodiments described are merely examples of the content of this disclosure and do not limit the scope of the invention. The technical features of each embodiment in the present invention can be combined accordingly, provided that there is no mutual conflict.

[0038] like Figure 1-7 As shown, this embodiment provides a tendon-driven flexible gripper based on the folding design of Miura sheet material, which includes a drive input module 1, a fixed support platform 2, a sliding platform 3, and a Miura sheet material substrate 4. The drive input module 1 consists of a turntable 11 and a transmission rope system 12. The turntable surface is designed with fitting grooves 13, which can be inserted into the turntable to drive the transmission rope system. The transmission rope system 12 has a triangular closed-path design, so the clockwise and counterclockwise rotation of the turntable will cause the transmission rope system 12 to rotate clockwise and counterclockwise, respectively.

[0039] The fixed support platform 2 includes a fixed end 21, a guide rail 22, and a distal closed end 23. The guide rail 22, with its rounded rectangular cross-section and parallel vertical distribution, is fixedly connected to the fixed end 21. The fixed end 21 has vertical through holes 24 for connection to the Miura sheet substrate. This connection method does not require a fixed fixation; it is sufficient to ensure that the fixed end and the Miura sheet substrate do not slip relative to each other. Bolts can be used for this connection. The distal closed end is designed with grooves 25 corresponding to the guide rails, allowing for a snug fit. Both the distal closed end and the fixed end have through holes 26 for rope arrangement.

[0040] The sliding platform 3 has grooves 31 on its upper and lower surfaces corresponding to the shape of the guide rails, allowing it to slide on the guide rails via power transmitted through the rope system. A through hole 32 in the middle of the sliding platform is used for arranging the transmission rope system, thus fixing the rope system to the sliding platform. There are no fixed requirements regarding the connection method between the rope system and the sliding platform, as long as there is no relative slippage between them (e.g., the rope system can be knotted at both ends of the hole to limit its movement).

[0041] When the Miura sheet substrate of the present invention is fully unfolded, its main body is rectangular. A rectangular fixing part is provided extending outward from the center of each of the two long sides of the main body. One rectangular fixing part is fixedly mounted on the sliding platform, and the other is fixedly mounted on the fixed bearing platform. When the sliding platform moves to one end of the guide rail, the Miura sheet substrate is fully unfolded. When the sliding platform moves to the other end of the guide rail, the Miura sheet substrate is folded along the preset crease line and forms a gripping state.

[0042] The main body has a long side length a = 2l and a short side length The length of the long side of the rectangular fixed part is c = b / 2, and the length of the short side is d = c / 3. The long side of the rectangular fixed part coincides with the long side of the main body. Let A be the two endpoints of the long side of the coinciding part. The distance from point A on the long side of the main body towards the short side is... Select point P4;

[0043] Let O be the center point of the main body, and B be the intersection of the median of the shorter side of the main body and the shorter side; the distance from point O on the line OB is... Points P1, P2, and P3 are selected respectively at the locations;

[0044] The crease lines on the left and right sides of the main body are completely symmetrical, and the crease lines on the top and bottom sides are completely symmetrical. Among them, points A and P1 on the same side are connected by a mountain crease line, points A and P2 are connected by a valley crease line, points P4 and P3 are connected by a mountain crease line, points O and P1 are connected by a valley crease line, points P1 and P2 are connected by a mountain crease line, points P2 and P3 are connected by a valley crease line, and points P3 and B are connected by a mountain crease line.

[0045] In this embodiment, the Miura board substrate 4 is on a flat board as shown in the image. Figure 7 Plan the crease lines. The flat panel consists of a square main body (main part) and upper and lower protruding square lugs. 41 (as a rectangular fixing part) ) Composition. The square lugs connect to the top and bottom boundaries of the square main body, serving as fixed connections to the fixed end of the fixed support platform and the sliding platform, respectively. The vertical center lines (long side center lines) of the square lugs and the square main body lie on the same straight line. The crease lines within the square main body consist of mountain crease lines (solid lines) and valley crease lines (dashed lines), exhibiting a centrally symmetrical distribution. The crease lines divide the origami panels and the base panel. 42、43、44、45 They are centrally symmetrically distributed. (Panel) 42 Located at the center of the upper half of the square main body, it has an isosceles trapezoidal shape. The upper base and waist are mountain fold lines, and the lower base is a valley fold line. The length of the upper base is a1, the length of the lower base is 2a1, and the angle between the waist and the vertical direction is θ1. Panel 43 close to the panel 42 It has a triangular shape, with its longest side being the valley crease line. The side coinciding with the horizontal center line of the square main body has a length of a2, and the top angle is θ2. Panel 44 close to the panel 43 It has a trapezoidal shape, with the lower base and shorter waist forming valley creases, and the upper base having a length of [missing information]. The length of the lower base is a3, and the angle between the shorter leg and the vertical direction is θ3. Panel 45 close to the panel 44 The sheet has a right-angled trapezoidal shape with a crease line on the bottom base, and the length of the bottom base is a4. This crease line design creates a spatial curvature angle similar to that of a human hand when folded, which is beneficial for gripping large objects. To ensure the gripping function of the claws, the ends of the claws formed after folding the sheet need to be in contact with each other. The relevant parameters need to satisfy the following two equations:

[0046] θ2=θ3

[0047] a4=a1+a3 cos 2θ2-a2 cos 2θ1

[0048] like Figure 1 , 2 As shown in Figures 7 and 8, the Miura board substrate in this embodiment is composed of... Figure 7The Miura sheet material is folded as shown. Before fabricating the substrate, a laser engraving machine is used to engrave the planned vertical and horizontal creases. Then, the upper and lower protruding square panels are fixedly connected to the fixed end of the fixed support platform and the sliding platform, respectively. When the flexible gripper of this invention is in operation, the transmission rope system drives the moving slide to move back and forth, causing the folding angle of the Miura sheet material substrate to change. When the turntable rotates counterclockwise, the transmission rope system drives the moving slide forward, changing the Miura sheet material substrate from a flat state to a folded clamping state; when the turntable rotates clockwise, the transmission rope system drives the moving slide backward, changing the Miura sheet material substrate from a folded clamping state to a flat state.

[0049] In a specific embodiment of the present invention, the Miura board substrate is made of 250g white cardboard. θ1 = θ2 = θ3 = 30°; the other parts are made using 3D printing to match the dimensions of the Miura sheet substrate, and the two are connected using M3 plastic screws.

[0050] The angle of the dihedral between the two panels in the center of the Miura board substrate can characterize the overall folding state of the substrate. Dividing this angle by two yields the corresponding cosine value. When fully unfolded, the dihedral angle is 180°, with a cosine value of 0; when fully folded, the dihedral angle is 0°, with a cosine value of 1. Therefore, real numbers in the range of 0-1 can be used to characterize the folding and filling, with 0 representing fully unfolded and 1 representing fully folded.

[0051] exist Figure 9 The image shows the shape of the central cross-section of the right half of the Miura sheet in different folded states, demonstrating the operating area of ​​the flexible origami gripper during the folding and closing process. The green line segment represents the fully unfolded state, and the corresponding markings are shown. Figure 7 Points O to B are considered. For ease of definition, the line segment from point O to point P1 is fixed on the horizontal coordinate axis. During the folding process, points P2, P3, and B will rotate around points P1, P2, and P3 respectively, thus achieving the unfolding and folding motion of the overall structure. Figure 10 The image shows the relationship between the distance between the center line of the short side and the intersection of the short side of the Miura sheet and the degree of folding. It can be seen that as the Miura sheet is fully unfolded to fully folded, the flexible gripper gradually clamps until it is completely closed.

[0052] like Figure 8As shown, a specific example of the present invention is used to grasp a target object. The target object can be of any shape. To facilitate the gripping force test, a ring with detachable counterweights was selected as the target object. Weights of different masses can be placed inside the ring to adjust the overall mass of the target object being grasped. After multiple tests on this specific example, a maximum gripping force of 5.42 N was obtained. This indicates that the designed flexible gripper possesses gripping capability. Figure 11 In this study, the maximum gripping capacity of a specific example of the flexible gripper proposed in this invention was tested under different degrees of folding. The obtained data was processed by spline interpolation to obtain a data graph, showing that the designed flexible gripper also has gripping capacity during folding. Furthermore, the crease design of this invention is simple, and the processing, manufacturing, and assembly are low-difficulty.

[0053] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. Those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A tendon-driven flexible gripper based on the Miura sheet folding design, characterized in that, include: Drive input module, fixed support platform, sliding platform and Miura sheet substrate; The drive input module includes a turntable and a transmission rope system driven by the turntable. The transmission rope system is designed as a closed path. The turntable is mounted on the fixed support platform and is used to receive external power input and drive the transmission rope system to move. The fixed bearing platform is provided with a guide rail, and the sliding platform is slidably mounted on the guide rail. The sliding platform is fixedly connected to the transmission rope system so as to move synchronously with the transmission rope system. When fully unfolded, the Miura sheet substrate has a rectangular main body. A rectangular fixing part extends outward from the center of each of the two long sides of the main body. One rectangular fixing part is fixed to the sliding platform, and the other is fixed to the fixed support platform. When the sliding platform moves to one end of the guide rail, the Miura sheet substrate is fully unfolded. When the sliding platform moves to the other end of the guide rail, the Miura sheet substrate folds along a preset crease line and forms a gripping state. The length of the long side of the main body portion Length of the shorter side ; Square fixed long side length Length of the shorter side The long side of the rectangular fixing part coincides with the long side of the main body, and the two endpoints of the overlapping long side are denoted as A; the distance from point A on the long side of the main body towards the short side is... Select point P4; Let O be the center point of the main body, and B be the intersection of the median of the shorter side of the main body and the shorter side; the distance from point O on the line OB is... , , Points P1, P2, and P3 are selected respectively at the locations; The crease lines on the left and right sides of the main body are completely symmetrical, and the crease lines on the top and bottom sides are completely symmetrical. Among them, points A and P1 on the same side are connected by a mountain crease line, points A and P2 are connected by a valley crease line, points P4 and P3 are connected by a mountain crease line, points O and P1 are connected by a valley crease line, points P1 and P2 are connected by a mountain crease line, points P2 and P3 are connected by a valley crease line, and points P3 and B are connected by a mountain crease line.

2. The tendon-driven flexible gripper based on the Miura sheet folding design according to claim 1, characterized in that, The rectangular fixing part has a circular hole with a diameter of c / 10 at a distance c / 10 from the edge of the two short sides along the center line of the short side. The circular holes are used to connect the sliding platform or the fixed bearing platform.

3. The tendon-driven flexible gripper based on the Miura sheet folding design according to claim 1, characterized in that, The turntable has a fitting groove on its circumference, and the transmission rope is partially set in the fitting groove of the turntable. The clockwise and counterclockwise rotation of the turntable will cause the transmission rope to drive the sliding platform to move backward and forward on the guide rail, respectively.

4. The tendon-driven flexible gripper based on the Miura sheet folding design according to claim 1, characterized in that, The fixed bearing platform includes a fixed end, a guide rail, and a remote closed end; the fixed end and the remote closed end are located at both ends of the guide rail, and the fixed bearing platform is fixedly connected to a rectangular fixed part of the Miura sheet substrate through the fixed end; both the remote closed end and the fixed end have through holes for the transmission rope to pass through.

5. The tendon-driven flexible gripper based on the Miura sheet folding design according to claim 4, characterized in that, The guide rail consists of two parallel guide plates, and the sliding platform is positioned between the two guide plates. The distal end of the closed end is designed with a groove corresponding to the cross-sectional shape of the two guide plates. The distal end of the closed end is fitted into the guide plate through the groove to prevent the sliding platform from sliding off the rail.

6. The tendon-driven flexible gripper based on the Miura sheet folding design according to claim 1, characterized in that, The sliding platform has grooves corresponding to the shape of the guide rail, and the power transmitted by the transmission rope system slides on the guide rail; the middle of the sliding platform has a through hole for the arrangement of the transmission rope system, and the transmission rope system passes through the through hole and is fixedly connected to the sliding platform.

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