A lightweight mechanical arm and a large extension ratio grabbing device based on series connection of different paper folding units

Abstract

The application discloses a lightweight mechanical arm and a large-stretch-ratio grabbing device based on series connection of different paper folding units. In the application, two types of paper folding units are connected in series to form a main structure of the mechanical arm, and a mechanical gripper with a large stretch ratio is arranged at the end of the main structure. Driving members are arranged in each paper folding unit to make the paper folding units deform, that is, different paper folding units produce axial expansion-bending deformation or expansion-torsion deformation, so that multi-mode movement of the axial expansion, bending and torsion of the mechanical arm is realized. The mechanical gripper at the end of the mechanical arm has a small transverse size in the contracted state, and can form a large envelope range in the expanded state, so that adaptive covering and grabbing of target objects of different sizes are realized.

Description

Technical Field

[0001] This invention belongs to the field of robotic arms, specifically relating to a lightweight robotic arm and a high extension ratio grasping device based on the series connection of different origami units. Background Technology

[0002] Traditional robotic arms are mostly open-chain structures composed of links and joints, which limit their motion capabilities and performance. To achieve torsion, traditional robotic arms face the following limitations:

[0003] First, the torsional capacity of traditional robotic arms is limited by the wrist joint. In certain postures, even with the joint motors functioning normally, the end effector cannot complete continuous torsional movements. In actual operation, due to material elasticity, gear backlash, and assembly errors, the connecting rods of the robotic arm undergo slight deformation during torsion. This deformation is amplified in multi-stage transmission, causing the actual end effector posture to deviate from the theoretical value. Especially during high-speed or heavy-load torsion, the elastic deformation of the harmonic reducer introduces hysteresis errors, severely affecting dynamic accuracy.

[0004] Secondly, the torsional capacity of a robotic arm is also limited by its links. For example, excessively long links reduce rigidity and affect torsional accuracy; while unreasonable joint offsets can lead to increased motion coupling, causing unexpected lateral deviations when performing torsional tasks.

[0005] In addition, traditional robotic arms require internal air tubes, cables, and signal lines, which are prone to entanglement and damage when the wrist twists continuously beyond 360°. Excessive rotation is typically prevented through software or mechanical limits.

[0006] In summary, traditional robotic arms have relatively complex structures and poor adaptability to scenarios such as human-robot collaboration and dynamic torsional grasping. Therefore, there is a need to propose a robotic arm structure that can simplify the structure, offer diverse torsional motion modes, and provide a large torsional working range while ensuring accuracy and load capacity. Summary of the Invention

[0007] To address the problems and needs in the background technology, this invention proposes a lightweight robotic arm and a high extension ratio gripping device based on the series connection of different origami units.

[0008] The technical solution of the present invention is as follows:

[0009] In a first aspect, the present invention proposes a lightweight robotic arm based on the series connection of different origami units, the robotic arm comprising:

[0010] Mechanical grippers are used to grasp target objects;

[0011] The torsion drive module, connected to the mechanical gripper, is used to control the axial extension-torsion coupling action of the robotic arm;

[0012] The telescopic drive module, connected to the torsion drive module, is used to control the axial extension and bending movements of the robotic arm.

[0013] The telescopic drive module includes multiple first folding driver units connected in series along the axis of the robotic arm.

[0014] Each of the first origami driver units includes a Miura derivative origami driver unit, which includes a Miura derivative origami structure disposed between a first end plate and a second end plate. The interior of the Miura derivative origami structure is hollow. Several driving components are also installed between the first end plate and the second end plate. All driving components are disposed inside the Miura derivative origami structure. The driving of each driving component causes the first end plate and the second end plate to move closer or further apart.

[0015] A retainer is also provided between the first end plate and the second end plate, and the retainer is connected to the middle of the inner wall of the Miura-derived origami structure.

[0016] The torsion drive module includes multiple second folding driver units connected in series along the axis of the robotic arm.

[0017] The second origami driver unit includes a Kresling origami driver unit, which includes a Kresling origami structure disposed between a third end plate and a fourth end plate. The interior of the Kresling origami structure is hollow. A driving component is also installed between the third end plate and the fourth end plate. All driving components are disposed inside the Kresling origami structure. The driving of each driving component causes the third end plate and the fourth end plate to move closer or further apart.

[0018] The drive component includes a two-way shape memory alloy spring and a spring mounting component. Each spring mounting component is installed in a corresponding end plate, and the two ends of the two-way shape memory alloy spring are respectively set in the corresponding spring mounting component.

[0019] The mechanical gripper includes a drive rod disposed in the mounting base plate, and several finger assemblies are also mounted on the mounting base plate outside the drive rod. The finger assemblies are arranged at intervals along the circumference, and each finger assembly is connected to the drive rod.

[0020] Secondly, the present invention proposes a gripping device, which includes a lightweight robotic arm based on different origami units connected in series as described in the first aspect.

[0021] The present invention has the following beneficial effects:

[0022] This invention combines origami units of different structures in series, enabling the robotic arm to perform axial extension, bending, twisting, and even other possible compound movements, thereby improving the adjustment capability of the robotic arm's end-effector posture and also featuring lightweight characteristics.

[0023] The mechanical gripper proposed in this invention has a large extension ratio, that is, it has a small lateral dimension in the contracted state and can form a large envelope range in the extended state, which can realize adaptive envelopment and gripping of targets of different sizes.

[0024] Therefore, the robotic arm proposed in this invention integrates lightweight design, multi-mode motion capability, and wide-range grasping capability, making it suitable for scenarios such as space debris capture, confined space operations, and complex environment operations. Attached Figure Description

[0025] Figure 1 This is an overall structural diagram of the present invention;

[0026] Figure 2 This is an overall structural diagram of the Miura-derived origami driver unit;

[0027] Figure 3 Cross-sectional view of the overall structure of the Miura-derived origami driver unit Figure 1 ;

[0028] Figure 4 Cross-sectional view of the overall structure of the Miura-derived origami driver unit Figure 2 ;

[0029] Figure 5 This is an overall structural diagram of the Kresling origami driver unit;

[0030] Figure 6 Cross-sectional view of the overall structure of the Kresling origami driver unit Figure 1 ;

[0031] Figure 7 Cross-sectional view of the overall structure of the Kresling origami driver unit Figure 2 ;

[0032] Figure 8 This is an overall structural diagram of the spring mounting component;

[0033] Figure 9 A cross-sectional view of the assembly of the spring mounting component and the two-way shape memory alloy spring;

[0034] Figure 10 This is a structural diagram of the mechanical gripper;

[0035] Figure 11 This is a diagram showing the retracted state of the mechanical gripper;

[0036] Figure 12 This is a diagram showing the unfolded state of the mechanical gripper;

[0037] Figure 13 This is a plan view of the Miura-derived origami structure;

[0038] In the diagram: 1-Miura-derived origami actuator unit, 2-Kresling origami actuator unit, 3-Mechanical gripper, 4-Miura-derived origami structure, 5-First end plate, 6-Second end plate, 7-Cage, 8-Two-way shape memory alloy spring, 9-Spring mount, 10-Kresling origami structure, 11-Third end plate, 12-Fourth end plate, 14-Mounting base plate, 15-Drive rod, 16-First traction rope, 17-First link, 18-Second link, 19-Third link, 20-Fourth link, 21-Fifth link, 22-Sixth link, 23-Second traction rope. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0040] like Figure 1 As shown, the lightweight robotic arm based on the cascading of different origami units proposed in this invention includes:

[0041] Mechanical gripper 3, used to grasp the target object;

[0042] The torsion drive module connected to the mechanical gripper 3 is used to control the axial extension-torsion coupling action of the robotic arm;

[0043] The telescopic drive module, connected to the torsion drive module, is used to control the axial extension and bending movements of the robotic arm.

[0044] In the initial state, the central axes of the mechanical gripper 3, the torsion drive module, and the telescopic drive module are straight lines. The torsion drive module and the telescopic drive module are arranged sequentially along the same axis, forming a continuous folding drive structure.

[0045] In one feasible implementation, the telescopic drive module includes a plurality of first folding driver units connected in series along the axial direction of the robotic arm.

[0046] In one feasible implementation, each first origami actuator unit includes a Miura-derived origami actuator unit 1, such as... Figure 2As shown, the Miura derivative origami driver unit 1 includes a Miura derivative origami structure 4 disposed between a first end plate 5 and a second end plate 6. The interior of the Miura derivative origami structure 4 is hollow. Several driving components are also installed between the first end plate 5 and the second end plate 6. All driving components are disposed inside the Miura derivative origami structure 4. The driving of each driving component causes the first end plate 5 and the second end plate 6 to move closer or further apart.

[0047] For structural simplicity and ease of installation, in actual implementation, for two adjacent Miura derivative origami driver units 1, the first end plate 5 of one Miura derivative origami driver unit 1 and the second end plate 6 of the other Miura derivative origami driver unit 1 can be combined into one end plate. The spring mounting member 9 and the Miura derivative origami structure 4 of one Miura derivative origami driver unit 1 and the spring mounting member 9 and the Miura derivative origami structure 4 of the other Miura derivative origami driver unit 1 are respectively connected to the same end plate.

[0048] In one feasible implementation, a retainer 7 is further provided between the first end plate 5 and the second end plate 6. The retainer 7 is connected to the middle of the inner wall of the Miura-derived origami structure 4. Specifically, the outer wall of the retainer 7 is tightly adhered to the middle of the inner wall of the Miura-derived origami structure 4. The retainer 7 is used to ensure the stability of the Miura-derived origami structure 4 during folding. The retainer is a rigid structure and will not deform under normal circumstances.

[0049] In one feasible implementation, the torsion drive module includes a plurality of second folding driver units connected in series along the axial direction of the robotic arm.

[0050] In one possible implementation, the second origami actuator unit includes a Kresling origami actuator unit 2, such as... Figure 5 and Figure 6 As shown, the Kresling origami driver unit 2 includes a Kresling origami structure 10 disposed between the third end plate 11 and the fourth end plate 12. The interior of the Kresling origami structure 10 is hollow. A driving component is also installed between the third end plate 11 and the fourth end plate 12. All driving components are disposed inside the Kresling origami structure 10. The driving of each driving component causes the third end plate 11 and the fourth end plate 12 to move closer or further apart.

[0051] For structural simplicity and ease of installation, in actual implementation, for two adjacent Kresling origami driver units 2, the third end plate 11 of one Kresling origami driver unit 2 and the fourth end plate 12 of the other Kresling origami driver unit 2 can be combined into one end plate. The spring mounting member 9 and the Kresling origami structure 10 of one Kresling origami driver unit 2 and the spring mounting member 9 and the Kresling origami structure 10 of the other Kresling origami driver unit 2 are respectively connected to the same end plate.

[0052] like Figure 3 As shown, the driving component includes a two-way shape memory alloy spring 8 and a spring mounting component 9. The first end plate 5, the second end plate 6, the third end plate 11 and the fourth end plate 12 are respectively equipped with corresponding spring mounting components 9. The two ends of the two-way shape memory alloy spring 8 are respectively set in the spring mounting components 9 corresponding to the first end plate 5 and the second end plate 6.

[0053] One feasible implementation method is, for example Figure 9 As shown, the spring mounting component 9 has an axially extending receiving cavity inside. A helical guide structure matching the end of the two-way shape memory alloy spring 8 is formed within the receiving cavity, i.e., a cylindrical helical cavity is formed, such as... Figure 8 As shown, the end of the two-way shape memory alloy spring 8 can be screwed into and embedded in the spring mounting part 9 along the helical guide structure, thereby achieving the limiting of the two-way shape memory alloy spring 8.

[0054] During the driving process of the Kresling origami driver unit 2, relative torsion occurs between the third end plate 11 and the fourth end plate 12. Since the spring mounting member 9 of the present invention is provided with a cylindrical spiral cavity, the two-way shape memory alloy spring 8 and the spring mounting member 9 can rotate relative to each other, thereby releasing the torque of the spring.

[0055] Miura derivative origami structure 4 is obtained by transforming the four parallelograms in the classic Miura origami into two right trapezoids and two isosceles triangles, and modifying some of the crease types, such as... Figure 13 As shown in the figure, the solid lines inside the quadrilateral are mountain folds, and the dashed lines are valley folds.

[0056] Specifically:

[0057] First, retaining the intersection point of the main creases at the center of the classic Miura origami unit and their connection relationship, adjust the diagonal outer contour edges on both sides to vertical boundaries, transforming the outer contour of the entire unit from the original parallelogram to a rectangle, and setting all outer contours as mountain creases; then, move the intersection point of the main creases at the center to the left along the original horizontal crease, so that the length of the mountain crease in the horizontal crease is consistent with the width of the upper origami part. Further, change the mountain creases in the upper and lower origami areas of the classic Miura origami pattern to valley creases, and move the endpoint of the valley crease on the upper contour to the left endpoint of the upper contour; similarly, move the endpoint of the valley crease on the lower contour to the left endpoint of the lower contour. Thus, the Miura-derived origami structure 4 used in this invention is obtained.

[0058] In one feasible implementation, the two-way shape memory alloy spring 8 is made of nickel-titanium alloy and has a cylindrical helix shape. This invention primarily utilizes its temperature-controlled two-way shape memory effect for actuation. Specifically: at room temperature, the spring material is in a fully martensitic phase, resulting in a small pitch and short spring length; when the material temperature rises to the austenitic phase transformation completion temperature, it transforms from a fully martensitic phase to a fully austenitic phase, simultaneously causing macroscopic deformation, manifested as an increase in pitch and a longer spring length; when the temperature drops to the martensitic phase transformation completion temperature, it transforms from a fully austenitic phase to a fully martensitic phase, simultaneously causing macroscopic deformation, manifested as the pitch and spring length returning to their initial smaller values.

[0059] In this invention, by applying current to a two-way shape memory alloy spring 8, due to the Joule heating effect, the spring 8 heats up to a certain temperature, causing its material to transform from a fully martensitic phase to a fully austenitic phase and resulting in macroscopic deformation. This deformation is mainly manifested in the spring's mean diameter and spring wire diameter remaining essentially unchanged, while the pitch and spring length increase. After the power is turned off, the spring cools naturally, its material transforms from a fully austenitic phase to a fully martensitic phase, and the spring retracts. This retraction is mainly manifested in the spring's mean diameter and spring wire diameter remaining essentially unchanged, while the pitch and spring length return to their initial values.

[0060] Each Miura-derived origami driver unit 1 contains multiple spaced-apart drive components. For example... Figure 4 As shown, each Miura-derived origami actuator unit 1 has four actuators located at the four corners of the end plate. This means there are four two-way shape memory alloy springs 8 and eight spring mounts 9. The four actuators are evenly spaced along the circumference of the robotic arm, meaning adjacent actuators are spaced 90° apart.

[0061] Since there are four bidirectional shape memory alloy springs 8, each spring 8 can be controlled individually to change its length. If all four springs 8 are heated simultaneously, they extend together, moving the first end plate 5 and the second end plate 6 further apart. If only two adjacent springs 8 are heated simultaneously, the first end plate 5 and the second end plate 6 are not parallel, but at an angle, allowing the telescopic module to bend. Force is transmitted between the first end plate 5, the bidirectional shape memory alloy springs 8, the spring mounting component 9, and the second end plate 6. The coordinated drive of multiple Miura-derived origami actuator units 1 enables the axial extension, retraction, and bending of the robotic arm. After all the bidirectional shape memory alloy springs 8 cool down, they return to their initial state.

[0062] like Figure 6 As shown, each Kresling origami actuator unit 2 has one driving component, namely a two-way shape memory alloy spring 8, which is located at the central axis of the Kresling origami actuator unit 2. When the two-way shape memory alloy spring 8 is heated in a controlled manner, its length increases, causing the third end plate 11 and the fourth end plate 12 in the Kresling origami actuator unit 2 to move away from each other. Combined with the inherent motion properties of the Kresling origami structure 10, this causes the Kresling origami actuator unit 2 to exhibit axial extension-torsion motion, such as... Figure 7 As shown, this enables the torsion drive module to generate axial extension-torsion motion. The two-way shape memory alloy spring 8 returns to its initial state after cooling.

[0063] like Figure 10 As shown, the mechanical gripper 3 includes a drive rod 15 disposed in the mounting base plate 14, and the mounting base plate 14 and the drive rod 15 form a sliding kinematic pair; one end of the drive rod 15 is hinged with multiple finger assemblies, and the other end of the drive rod 15 is connected to a first traction rope 16 for controlling the closing of the mechanical gripper 3. Several finger assemblies are also connected to the mounting base plate 14 outside the drive rod 15, and the finger assemblies are arranged at circumferential intervals.

[0064] Specifically:

[0065] Each finger assembly includes a first link 17, a second link 18, a third link 19, a fourth link 20, a fifth link 21, and a sixth link 22. These links are connected by hinges to form a linkage structure. One end of the first link 17 is hinged to the mounting base plate 14. The other end of the first link 17 is hinged to the third link 19 via the second link 18. The inner side of the first link 17 near the end of the second link 18 is hinged to the drive rod 15 via the sixth link 22. The end of the third link 19 away from the second link 18 is hinged to the end of the second link 18 away from the third link 19 via the fourth link 20. The end of the second link 18 away from the third link 19 is also hinged to the drive rod 15 via the fifth link 21. The hinge points of the sixth link 22 and the drive rod 15, and the hinge points of the fifth link 21 and the drive rod 15 are coaxial. One end of the second traction rope 23 is fixed to the inner wall of the first connecting rod 17, with the fixing point located at the end of the first connecting rod 17 near the second connecting rod 18. The other end of the second traction rope 23 passes around the reversing pulley fixed on the mounting base plate 14, then through the wire hole arranged on the mounting base plate 14, and finally leads out. The second traction rope 23 is used to control the opening and closing of the mechanical gripper 3. In this invention, the rope ends of the first traction rope 16 and the second traction rope 23 can be inserted inside the torsion drive module and the telescopic drive module, and finally led out from the telescopic drive module, or they can be led out directly from the bottom of the mounting base plate 14. By controlling the first traction rope 16 and the second traction rope 23 respectively, the closing and opening of the mechanical gripper 3 can be controlled to grasp the target object. The rope ends can be connected to external equipment or manually controlled.

[0066] The mechanical gripper 3 is a deployable structure, which is in a retracted configuration in its initial state, such as... Figure 11 As shown, the overall lateral dimension is relatively small. Pulling the first traction rope 16 causes it to extend outwards, significantly increasing the lateral dimension of the mechanical gripper 3. This results in a larger extension ratio, enabling the gripping of targets of different sizes, such as... Figure 12 As shown; after the gripping is completed, the second traction rope 23 can be pulled to control the mechanical gripper 3 to open, and the structure resets. Therefore, the mechanical gripper 3 proposed in this invention has a large extension ratio.

[0067] This invention combines origami units of different structures in series, enabling the robotic arm to perform axial extension, bending, and twisting movements, as well as compound movements, thereby improving the end effector's ability to adjust its posture and making it lightweight. This invention also enables the robotic arm to grasp different target objects through a mechanical gripper with a large extension ratio at the end effector.

[0068] The present invention also proposes a gripping device comprising a lightweight robotic arm and a mechanical gripper with a large extension ratio.

[0069] The above embodiments are used to explain and illustrate the present invention, but not to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A lightweight robotic arm based on the series connection of different origami units, characterized in that, include: Mechanical gripper (3) is used to grasp the target object; The torsion drive module connected to the mechanical gripper (3) is used to control the axial extension-torsion coupling action of the robotic arm; The telescopic drive module, connected to the torsion drive module, is used to control the axial extension and bending movements of the robotic arm.

2. The lightweight robotic arm based on the series connection of different origami units according to claim 1, characterized in that, The telescopic drive module includes multiple first folding driver units connected in series along the axis of the robotic arm.

3. A lightweight robotic arm based on the series connection of different origami units according to claim 2, characterized in that, Each of the first origami driver units includes a Miura derivative origami driver unit (1), which includes a Miura derivative origami structure (4) disposed between the first end plate (5) and the second end plate (6). The interior of the Miura derivative origami structure (4) is hollow. Several driving members are also installed between the first end plate (5) and the second end plate (6). All driving members are disposed inside the Miura derivative origami structure (4). The driving of each driving member causes the first end plate (5) and the second end plate (6) to move closer or further apart.

4. A lightweight robotic arm based on the series connection of different origami units according to claim 3, characterized in that, A retainer (7) is also provided between the first end plate (5) and the second end plate (6), and the retainer (7) is connected to the middle of the inner wall of the Miura-derived origami structure (4).

5. A lightweight robotic arm based on the series connection of different origami units according to claim 1, characterized in that, The torsion drive module includes multiple second folding driver units connected in series along the axis of the robotic arm.

6. A lightweight robotic arm based on the series connection of different origami units according to claim 5, characterized in that, The second origami driver unit includes a Kresling origami driver unit (2), which includes a Kresling origami structure (10) disposed between a third end plate (11) and a fourth end plate (12). The interior of the Kresling origami structure (10) is hollow. A driving member is also installed between the third end plate (11) and the fourth end plate (12). All driving members are disposed inside the Kresling origami structure (10). The driving of each driving member causes the third end plate (11) and the fourth end plate (12) to move closer or further apart.

7. A lightweight robotic arm based on the series connection of different origami units according to claim 3 or 6, characterized in that, The drive unit includes a two-way shape memory alloy spring (8) and a spring mounting component (9). Each spring mounting component (9) is installed in a corresponding end plate, and the two ends of the two-way shape memory alloy spring (8) are respectively set in the corresponding spring mounting component (9).

8. A lightweight robotic arm based on the series connection of different origami units according to claim 1, characterized in that, The mechanical gripper (3) includes a drive rod (15) disposed in the mounting base plate (14). Several finger assemblies are also installed on the mounting base plate (14) outside the drive rod (15). The several finger assemblies are arranged at intervals along the circumference, and each finger assembly is connected to the drive rod (15).

9. A gripping device, characterized in that, Includes a lightweight robotic arm based on the series connection of different origami units as described in claim 1.

Images