Single-degree-of-freedom multi-finger mechanical gripper based on worm and gear transmission

Abstract

The invention provides a single-degree-of-freedom multi-finger mechanical gripper based on worm and gear transmission, and relates to the technical field of manipulators, the single-degree-of-freedom multi-finger mechanical gripper comprises a palm mechanism and a finger mechanism, the palm mechanism comprises a frame body, a driving device is mounted on the frame body, and an output shaft of the driving device is in transmission connection with a worm; the finger mechanism is composed of a plurality of sets of mechanical fingers, the mechanical fingers are circumferentially distributed at equal intervals along the axis of a worm gear, each mechanical finger is fixedly connected with one worm gear, and the worm gears are meshed with a worm to jointly form a single-degree-of-freedom plane coupling kinematic pair. When the driving device drives the worm to rotate, the worm drives the worm gear meshed with the worm to rotate synchronously, and then the multiple sets of mechanical fingers are controlled to be unfolded or folded synchronously around the axis of the worm gear to form an annular enveloping surface, so that the object is grabbed. The four-degree-of-freedom transmission mechanism has the beneficial effects of being compact in structure, high in transmission efficiency, high in load capacity, accurate in control, high in torque amplification effect and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of manipulators, and in particular to a single-degree-of-freedom multi-finger manipulator gripper based on worm gear transmission. Background Art

[0002] As advanced automation equipment, robotic arms have undergone years of development and are now widely used in every aspect of modern industrial production. In industrial manufacturing, robotic arms, with their high precision, high efficiency, and high repeatability, undertake critical tasks such as component assembly, welding, painting, and polishing, significantly improving production efficiency and product quality while ensuring the safety, stability, and reliability of the production process.

[0003] However, some industrial robots currently on the market have complex designs and high costs in order to achieve high-precision gripping and high work reliability. Using such robots in simple workpiece processing environments will result in a waste of resources and significantly increase the company's production costs. In addition, most industrial robots are fixed to a single workstation and lack the ability to operate across workstations. In addition, in actual applications, traditional mechanical grippers have poor gripping posture stability. During the gripping, handling or assembly process, they are prone to shaking, offsetting, and even falling off. This poses a potential threat to production safety, reliability, and cost control. Therefore, improving the gripping stability of mechanical grippers is urgent.

[0004] Chinese patent publication CN119427413A discloses a copper and aluminum machining robot for metalworking applications. The robot consists of a multi-axis robotic arm, a mechanical gripper mounted at the front end of the arm, and a controller that controls the arm and gripper. The robot aims to address existing issues in automated machining processes, such as the significant deformation caused by high temperatures during machining when using automated mechanical fixtures to hold copper and aluminum workpieces, as well as the significant pressure exerted by the gripper after expansion. This approach ensures stable and effective gripping of the workpieces, avoids adverse conditions caused by high temperatures, and improves the yield rate of finished workpieces.

[0005] However, the robotic arm described in this patent has significant drawbacks. Its complex structure and numerous components not only increase the costs of equipment maintenance, debugging, and task switching, but also significantly reduce production efficiency. Furthermore, the large number of components used in pursuit of precision increases the weight of the mechanical gripper itself, directly affecting the load capacity and dynamic performance of the robotic arm. Therefore, it is necessary to develop a single-degree-of-freedom, multi-finger robotic gripper based on a worm gear transmission to overcome the shortcomings of the existing technology. Summary of the Invention

[0006] The present invention overcomes the shortcomings of the prior art and provides a single-degree-of-freedom multi-finger mechanical gripper based on worm gear transmission, which has multiple advantages such as compact structure, high transmission efficiency, high load capacity, precise control, and torque amplification effect.

[0007] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0008] A single-degree-of-freedom multi-finger mechanical gripper based on a worm gear transmission comprises a palm mechanism and a finger mechanism. The palm mechanism comprises a frame on which a drive device is mounted, and the output shaft of the drive device is in transmission connection with the worm gear. The finger mechanism comprises a plurality of groups of mechanical fingers, which are arranged in equidistant circular distribution along the axis of the worm gear. Each of the mechanical fingers is fixedly connected to a worm gear, and the worm gear and the worm gear mesh with each other to form a single-degree-of-freedom planar coupled kinematic pair.

[0009] When the driving device drives the worm to rotate, the worm drives the worm wheel meshing with it to rotate synchronously, thereby controlling several groups of mechanical fingers to expand or retract synchronously around the axis of the worm wheel to form an annular envelope surface, thereby realizing the grasping action of the object.

[0010] Furthermore, the mechanical fingers are in four groups and are symmetrically distributed in pairs.

[0011] Furthermore, the lead angle of the worm is smaller than the equivalent friction angle of the worm gear contact surface, thereby achieving a self-locking function of grasping and ensuring stability when grasping objects.

[0012] Furthermore, the frame includes a palm base, a plurality of supporting members and an annular drive fixing device; the mechanical finger is rotatably connected to the palm base; a worm threaded hole is opened at the center of the palm base, and support member threaded holes are evenly distributed around the worm threaded hole. The lower end of the worm is installed in the worm threaded hole in a threaded connection manner, and the lower end of the support member is also installed in the support member threaded hole in a threaded connection manner. The upper end of the support member and the annular drive fixing device form a limited moving pair.

[0013] Furthermore, the limiting movable pair includes a through-limiting hole on the annular driving fixture, and the supporting member includes a main rod and a coaxially extending protruding rod, wherein:

[0014] The main rod diameter is larger than the through-limiting hole diameter, forming an axial stop surface;

[0015] The diameter of the convex rod is adapted to the diameter of the through-limiting hole, the surface is processed with external threads and extends out of the through-limiting hole, and axial positioning is achieved through a locking nut.

[0016] Furthermore, a spring is sleeved on the protruding rod, and the spring is compressed between the top surface of the main rod and the bottom surface of the annular driving fixing device.

[0017] Furthermore, the clamping surface of the robotic finger is a bionic curved surface configuration, and the surface is processed by ultrasonic vibration to form a micron-level concave-convex texture with a surface roughness of Ra = 3.2~6.3μm; the robotic finger body is provided with a hollow weight-reducing structure to reduce the overall mass.

[0018] Furthermore, the mechanical finger and the corresponding worm wheel are matched through radial keyways to achieve circumferential positioning, and the matching interface is provided with a first limit pin for axial constraint; the worm and the output shaft of the driving device are matched through axial keyways to achieve torque transmission, and the matching interface is provided with a second limit pin for radial constraint.

[0019] Furthermore, a mechanical limiting structure is provided on the frame, which is used to limit the effective deployment angle range of a single mechanical finger to 10° to 60°.

[0020] Furthermore, the worm gear transmission adopts a two-stage transmission structure to achieve a specific transmission ratio.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The worm gear transmission device designed for the single-degree-of-freedom multi-finger mechanical gripper based on worm gear transmission described in the present invention has the characteristics of compact structure, high transmission efficiency, high load capacity, precise control, torque amplification effect, etc. Its self-locking property can maintain the grasping posture after the motor stops rotating and maintain the grasping position when the power is off, effectively ensuring safety.

[0023] The worm-gear-based, single-degree-of-freedom, multi-finger robotic gripper described in this invention exhibits excellent environmental adaptability. The mechanical finger design features biomimetic curved surfaces at the knuckles and biomimetic non-slip surface treatment at the fingertips. Each finger's rotation angle is controlled by a worm gear, and when the four fingers are symmetrically closed, they form a circular envelope, adaptable to objects of varying shapes.

[0024] 3. The single-degree-of-freedom, multi-finger mechanical gripper based on a worm gear transmission described in this invention offers high grasping stability. The symmetrical structure of the fingers, coupled with the worm gear's two-stage reduction mechanism and torque amplification effect, and the coupled palm mechanism prevent the worm gear from interfering with the grasping process, significantly improve the gripper's grasping stability.

[0025] 4. The single-degree-of-freedom, multi-finger robotic gripper based on worm gear transmission described in this invention incorporates lightweight design principles. The finger components are hollowed out, and each of the four fingers is driven solely by the active worm gear to complete both the opening and closing movements. This reduction in drive units significantly reduces the overall weight of the gripper.

[0026] 5. The single-degree-of-freedom, multi-finger mechanical gripper based on a worm gear transmission described in this invention exhibits excellent control performance. This design, using a worm gear mechanism as the drive device, simply rotates the worm to drive the rotation of four sets of worm gears, which are symmetrically distributed around the worm. This greatly simplifies the control logic and effectively improves the efficiency and precision of the mechanism's drive control. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are used to provide a further understanding of the present invention and are used to explain the present invention together with the embodiments of the present invention, but do not constitute a limitation of the present invention. In the accompanying drawings:

[0028] Figure 1 It is a three-dimensional diagram of the mechanical gripper in the open state;

[0029] Figure 2 It is a front view of the mechanical gripper in the open state;

[0030] Figure 3 It is a three-dimensional diagram of the mechanical gripper in the retracted state;

[0031] Figure 4 Is the front view of the mechanical gripper's gripping state Figure 1 ;

[0032] Figure 5 Is the front view of the mechanical gripper's gripping state Figure 2 ;

[0033] Figure 6 It is a three-dimensional diagram of the mechanical finger and worm gear;

[0034] Figure 7 It is a structural diagram of the palm base;

[0035] Figure 8 It is a structural diagram of the frame;

[0036] Figure 9 It is a structural diagram of worm gear transmission;

[0037] Figure 10 It is a schematic diagram of the structure of the driving device and the worm;

[0038] Figure 11 yes Figure 5 Enlarged view of the circled area in center A.

[0039] In the picture:

[0040] 1. Palm mechanism; 101. Frame; 1011. Palm base; 10111. Threaded hole of worm; 10112. Threaded hole of supporting member; 1012. Supporting member; 10121. Main rod; 10122. Protruding rod; 1013. Annular drive fixing device; 10131. Through-limiting hole; 2. Finger mechanism; 201. Mechanical finger; 3. Worm; 4. Worm gear; 5. Locking nut; 6. Spring; 7. Radial keyway; 8. Axial keyway; 9. Driving device. DETAILED DESCRIPTION

[0041] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0042] like Figures 1 to 11 As shown, the present invention claims protection for a single-degree-of-freedom multi-finger mechanical gripper based on a worm gear transmission, comprising a palm mechanism 1 and a finger mechanism 2. The palm mechanism 1 comprises a frame 101, which mainly serves as a support and fixation. A drive device 9 is mounted on the frame 101. In this embodiment, the drive device 9 is a servo drive motor with precise operation and good stability. The output shaft of the drive device 9 is connected to the worm 3 in a transmission manner. Specifically, Figure 10 It can be seen that the worm 3 and the output shaft of the driving device 9 cooperate through the axial keyway 8 to realize torque transmission, and a second limit pin is provided on the matching interface for radial constraint, which is conducive to the driving device 9 to stably drive the worm 3 to rotate without slipping.

[0043] The finger mechanism 2 is composed of several groups of mechanical fingers 201, which are arranged in an equidistant circular distribution along the axis of the worm gear 4. In this embodiment, there are four groups of mechanical fingers 201, and they are symmetrically distributed in pairs. The structure is symmetrical and the inclusion stability is good. Each mechanical finger 201 is fixedly connected to a worm gear 4. Figure 6 It can be seen that the mechanical finger 201 and the corresponding worm wheel 4 are matched through the radial keyway 7 to achieve circumferential positioning. The first limit pin is provided on the matching interface for axial constraint, which is conducive to the worm wheel 4 to stably drive the mechanical finger 201 to rotate together. The worm wheel 4 and the worm 3 are meshed with each other, forming a single-degree-of-freedom planar coupled kinematic pair.

[0044] Therefore, when the driving device 9 drives the worm 3 to rotate, the worm 3 drives the worm wheel 4 meshing with it to rotate synchronously, thereby controlling several groups of mechanical fingers 201 to expand or retract synchronously around the axis of the worm wheel 4, forming an annular envelope surface, thereby realizing the grasping action of the object.

[0045] The lead angle of the worm 3 is smaller than the equivalent friction angle of the worm gear contact surface, thereby achieving a self-locking function of grasping and ensuring stability when grasping objects.

[0046] The frame 101 includes a palm base 1011, a plurality of support members 1012 and an annular drive fixing device 1013; the mechanical finger 201 is rotatably connected to the palm base 1011; a threaded hole 10111 for the worm 3 is provided at the center of the palm base 1011, and threaded holes 10112 for the support members are evenly distributed around the threaded hole 10111 for the worm 3. The lower end of the worm 3 is installed in the threaded hole 10111 for the worm 3 in a threaded connection manner, and the lower end of the support member 1012 is also installed in the threaded hole 10112 for the support member in a threaded connection manner. The upper end of the support member 1012 and the annular drive fixing device 1013 form a limited moving pair. Specifically, as Figure 11 As shown, the limiting movable pair includes a through-limiting hole 10131 in the annular drive fixture 1013, and the support member 1012 includes a main rod 10121 and a coaxially extending protruding rod 10122. The main rod 10121 has a diameter larger than the through-limiting hole 10131, forming an axial stop surface. The protruding rod 10122 has a diameter adapted to the through-limiting hole 10131, is externally threaded, and extends beyond the through-limiting hole 10131, achieving axial positioning via a locking nut 5. Due to the interaction between the worm 3 and the threaded hole 10111 during rotation, the palm base 1011 moves relative to the annular drive fixture 1013. This limiting movable pair allows for a certain degree of mobility between the support member 1012 and the annular drive fixture 1013. Furthermore, the threaded fixing method facilitates assembly and disassembly of the frame 101.

[0047] In addition, a spring 6 can be sleeved on the protruding rod 10122. The spring 6 is compressed between the top surface of the main rod 10121 and the bottom surface of the annular driving fixing device 1013. The function of the spring 6 is to limit the displacement of the driving device 9. When the driving motor of the driving device 9 rotates, the worm 3 and the frame 1011 connected thereto will be displaced. The function of the spring 6 is to provide a certain auxiliary driving force. In addition, the initial preload force of the spring 6 can be set to 50~100N to compensate for the assembly gap and suppress vibration.

[0048] The clamping surface of the robotic finger 201 has a bionic curved surface configuration, and the surface is processed by ultrasonic vibration to form a micron-level concave-convex texture with a surface roughness of Ra = 3.2~6.3μm. In this embodiment, the surface roughness is Ra = 4.5μm, which improves the gripping friction coefficient; the body of the robotic finger 201 is provided with a hollow weight-reducing structure to reduce the overall mass.

[0049] In addition, a mechanical limiting structure is provided on the frame 101 , which may be a bump provided on the palm base 1011 , for limiting the effective deployment angle range of a single mechanical finger 201 to 10° to 60°.

[0050] The worm gear transmission adopts a two-stage transmission structure to achieve a specific transmission ratio; the two-stage transmission structure achieves a two-stage reduction structure design and a torque amplification effect, significantly improving the gripping stability of the mechanical gripper.

[0051] The single-degree-of-freedom multi-finger mechanical gripper based on worm gear transmission is in a retracted posture when not in operation. When it enters the operation state and completes the positioning of the target grasping object, the worm 3 can be driven by a simple and reliable driver such as the drive device 9 (servo drive motor). Through the force of the drive device 9, the single-degree-of-freedom multi-finger mechanical gripper based on the worm gear transmission can adjust the expansion speed by the rotation speed of the drive device 9, forming a grasping range with an adjustable envelope size, and grasping the target. In general, the single-degree-of-freedom multi-finger mechanical gripper based on the worm gear transmission has high grasping stability and reliability, and has a single-degree-of-freedom drive characteristic. The single-degree-of-freedom drive mode combined with the self-locking characteristics of the worm gear improves the stress condition of the overall mechanism grasping process, making the grasping process more stable and reliable. The bionic curved surface design and multi-finger characteristics of the mechanical finger 201 meet the grasping requirements of various shapes of targets in actual working conditions.

[0052] The support structure of the multiple finger mechanisms 2 is designed to be symmetrical, with the worm 3 at the center. This approach effectively distributes the load and significantly reduces localized stress concentration. During high-load operation, this prevents structural damage caused by stress concentration and significantly improves the structural stability of the robotic finger 201.

[0053] To achieve the goal of reducing the weight of the worm gear transmission-based single-degree-of-freedom multi-fingered robotic finger 201 within a certain range while still maintaining good grasping stability, the contact surface of the robotic finger 201 is treated with a bionic anti-slip surface to increase the contact area between the fingers and the grasped object and improve the friction coefficient. Furthermore, the hollow structure design of the fingers not only reduces the mass of the multi-fingered robotic finger 201 but also indirectly improves the control accuracy of the robotic finger 201, effectively enhancing grasping stability, grasping adaptability, and grasping reliability.

[0054] In order to achieve good control performance of the single-degree-of-freedom multi-fingered robotic finger 201 based on worm gear transmission, a worm gear mechanism is used as the driving device 9 in the driver design. With this design, only the rotation of the worm 3 can drive the rotation of four groups of worm wheels 4 symmetrically distributed in pairs around the worm 3. This greatly simplifies the control logic, effectively improves the drive control efficiency and accuracy of the mechanism, and achieves efficient and stable operation.

[0055] The operating principle of this single-degree-of-freedom multi-finger mechanical gripper is as follows: the servo drive motor on the frame 101 serves as the drive device 9. Its output shaft and worm 3 are engaged through an axial keyway 8 and constrained by a second limit pin, stably transmitting torque to drive the rotation of the worm 3. The finger mechanism 2 comprises four groups of symmetrically distributed mechanical fingers 201, each fixedly connected to a worm gear 4, and synchronously rotating through radial keyways 7 and first limit pins. When the worm 3 rotates, the meshing worm gear 4 rotates synchronously, thereby controlling the mechanical fingers 201 to expand or contract around the axis of the worm gear 4. The expansion or contraction of the mechanical fingers 201 forms an annular envelope, enabling the grasping of objects. The lead angle of the worm 3 is less than the equivalent friction angle of the worm gear contact surface, achieving self-locking and ensuring stable grasping. Using a single drive device 9, all mechanical fingers 201 can be simultaneously driven, significantly reducing the number of actuators in the multi-finger mechanical gripper and simplifying the mechanical gripper's control system.

[0056] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. However, any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A single-degree-of-freedom multi-finger mechanical gripper based on a worm gear transmission, characterized by: The invention comprises a palm mechanism (1) and a finger mechanism (2), wherein the palm mechanism (1) comprises a frame (101), a driving device (9) is mounted on the frame (101), and an output shaft of the driving device (9) is connected to a worm (3) in a transmission manner; the finger mechanism (2) is composed of a plurality of groups of mechanical fingers (201), the plurality of groups of mechanical fingers (201) are arranged in an equidistant circular distribution along the axis of a worm wheel (4), each of the mechanical fingers (201) is fixedly connected to a worm wheel (4), and the worm wheel (4) and the worm (3) are meshed with each other to form a single-degree-of-freedom planar coupled motion pair; When the driving device (9) drives the worm (3) to rotate, the worm (3) drives the worm wheel (4) meshing therewith to rotate synchronously, thereby controlling a plurality of groups of mechanical fingers (201) to synchronously expand or retract around the axis of the worm wheel (4), forming an annular envelope surface, thereby achieving a grasping action for an object.

2. The single-degree-of-freedom multi-finger mechanical gripper based on worm gear transmission according to claim 1 is characterized in that: The mechanical fingers (201) are in four groups and are symmetrically distributed in pairs.

3. The single-degree-of-freedom multi-finger mechanical gripper based on worm gear transmission according to claim 1 is characterized in that: The lead angle of the worm (3) is smaller than the equivalent friction angle of the worm gear contact surface, thereby achieving a self-locking function during grasping and ensuring stability when grasping an object.

4. The single-degree-of-freedom multi-finger mechanical gripper based on worm gear transmission according to claim 1 is characterized in that: The frame (101) comprises a palm base (1011), a plurality of support members (1012) and an annular drive fixing device (1013); the mechanical finger (201) is rotatably connected to the palm base (1011); a worm screw thread hole (10111) is provided at the center of the palm base (1011), support member screw holes (10112) are evenly distributed around the worm screw thread hole (10111), the lower end of the worm (3) is mounted in the worm screw thread hole (10111) in a threaded connection manner, the lower end of the support member (1012) is also mounted in the support member screw hole (10112) in a threaded connection manner, and the upper end of the support member (1012) and the annular drive fixing device (1013) form a limited moving pair.

5. The single-degree-of-freedom multi-finger mechanical gripper based on worm gear transmission according to claim 4 is characterized in that: The limiting movable pair comprises a through-limiting hole (10131) on the annular driving fixture (1013), and the supporting member (1012) comprises a main rod (10121) and a coaxially extending protruding rod (10122), wherein: The diameter of the main rod (10121) is larger than the diameter of the through-limiting hole (10131), forming an axial stop surface; The diameter of the protruding rod (10122) is adapted to the aperture of the through-limiting hole (10131), and the surface is processed with an external thread and extends out of the through-limiting hole (10131), and axial positioning is achieved through the locking nut (5).

6. The single-degree-of-freedom multi-finger mechanical gripper based on worm gear transmission according to claim 5, characterized in that: The protruding rod (10122) is sleeved with a spring (6), which is compressed between the top surface of the main rod (10121) and the bottom surface of the annular driving fixing device (1013).

7. The single-degree-of-freedom multi-finger mechanical gripper based on worm gear transmission according to claim 5, characterized in that: The clamping surface of the mechanical finger (201) is a bionic curved surface configuration, and the surface is processed by ultrasonic vibration to form a micron-level concave-convex texture, with a surface roughness Ra=3.2-6.3 μm; the main body of the mechanical finger (201) is provided with a hollow weight-reducing structure to reduce the overall mass.

8. The single-degree-of-freedom multi-finger mechanical gripper based on worm gear transmission according to claim 5, characterized in that: The mechanical finger (201) and the corresponding worm wheel (4) cooperate through a radial keyway (7) to achieve circumferential positioning, and a first limit pin is provided on the cooperation interface for axial constraint; the worm (3) and the output shaft of the driving device (9) cooperate through an axial keyway (8) to achieve torque transmission, and a second limit pin is provided on the cooperation interface for radial constraint.

9. The single-degree-of-freedom multi-finger mechanical gripper based on worm gear transmission according to claim 1, characterized in that: The frame (101) is provided with a mechanical limiting structure for limiting the effective deployment angle range of a single mechanical finger (201) to 10° to 60°.

10. The single-degree-of-freedom multi-finger mechanical gripper based on worm gear transmission according to any one of claims 1 to 9, characterized in that: The worm gear transmission adopts a two-stage transmission structure to achieve a specific transmission ratio.

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