A variable stiffness flexible drive joint that can be used in humanoid robotic arms

Abstract

This invention discloses a variable stiffness flexible drive joint for use in humanoid robotic arms, comprising: an elastic input module and a variable stiffness module; the elastic input module includes a fixed component, a guide rail component, and an elastic component; the elastic component includes an optical axis fitted with a linear bearing and a spring component; the guide rail component includes a guide rail, a first slider component, and a guide rail pivot; one end of the guide rail is connected to the linear bearing via the first slider component, and the other end is connected via the guide rail pivot; the variable stiffness module includes a support, a lead screw component, a second slider component, and a variable stiffness driver; the guide rail pivot, driven by the fixed component, causes the guide rail to rotate around the lead screw nut, driving the first slider component to move, thereby causing the linear bearing to move elastically along the optical axis under the action of the spring. This drive joint achieves flexible variable stiffness adjustment, providing a new approach for humanoid joint design, and can be used as a component of a robotic arm, showing great application potential.

Description

Technical Field

[0001] This invention proposes a variable stiffness flexible drive joint, belonging to the field of robotics technology, and particularly relates to a variable stiffness flexible drive joint that can be used in humanoid robotic arms. Background Technology

[0002] Humanoid robotic arms can be categorized into rigid and flexible types based on the type of their driven joints. In work environments requiring high levels of human-computer interaction, flexible humanoid robotic arms hold greater potential. Humans and animals can utilize the elasticity of their muscles or tissues to store and release energy during movement; regulate energy distribution to enhance the instantaneous explosive force of joints; and also provide cushioning protection against external impacts. Therefore, the design technology of biomimetic driven joints is a significant challenge in robotics.

[0003] Compared to traditional rigid actuators, flexible joints offer superior robustness, task adaptability, and safety against external forces. Furthermore, this robustness, strong task adaptability, and low impedance capability allow for more effective handling of unknown contact forces when interacting with humans or complex environments. Therefore, developing variable stiffness actuators with flexible actuation capabilities, using biomimetic actuators as a key research breakthrough to improve the complex interaction capabilities, safety, and stability of humanoid robotic arms, is a major research direction in the field of robotics. Summary of the Invention

[0004] The purpose of this invention is to solve the problems existing in the background art and provide a variable stiffness flexible drive joint that can be used in humanoid robotic arms.

[0005] The technical solutions provided by the present invention are as follows:

[0006] In a first aspect, the present invention provides a variable stiffness flexible drive joint that can be used in a humanoid robotic arm, comprising: an elastic input module and a variable stiffness module;

[0007] The elastic input module includes a fixing component, a guide rail component, and an elastic component; the elastic component includes an optical shaft fitted with a linear bearing and a spring component; the guide rail component includes a guide rail, a first slider component, and a guide rail shaft; one end of the guide rail is connected to the linear bearing via the first slider component, and the other end is connected via the guide rail shaft; the fixing component is used to clamp the spring component, connects to the guide rail component via the guide rail shaft, and receives external power input;

[0008] The variable stiffness module includes a bracket, a lead screw assembly, a second slider assembly, and a variable stiffness driver; the lead screw assembly is fixed in the bracket, and its lead screw nut is connected to the guide rail through the second slider assembly; the variable stiffness driver is used to drive the lead screw; the bracket is movably connected to the fixed assembly.

[0009] Driven by the fixed component, the guide rail shaft rotates around the lead screw nut and drives the first slider assembly to move, thereby causing the linear bearing to move elastically along the optical axis under the action of the spring.

[0010] In one possible implementation, the spring assembly includes a fixed baffle, an optical axis fixing flange, and a compression spring connected in sequence; the fixed baffle is connected to a fixing assembly; and elastic components are provided at both ends of the optical axis.

[0011] In one possible implementation, the fixing component includes a first fixing ring, a first fixing plate, a second fixing ring, and a second fixing plate; the first fixing ring is disposed on the first fixing plate, and the second fixing ring is disposed on the second fixing plate, and the two are symmetrically arranged for clamping the guide rail assembly and the elastic assembly.

[0012] Furthermore, the external power input is achieved by driving the first or second retaining ring of the firmware component to input power.

[0013] In one possible implementation, the first slider assembly includes a rotary bearing, a slider rotating ring, and a first slider connected in sequence; the rotary bearing is connected to one side of the linear bearing; the first slider is placed on a guide rail and can slide along the guide rail; the slider assembly is symmetrically arranged on both sides of the linear bearing.

[0014] In one possible implementation, the bracket is a square frame, with one end movably connected to a fixing component via an axial fit.

[0015] In one possible implementation, the lead screw assembly includes a lead screw and a lead screw nut; the lead screw nut is disposed in a guide rail, between the rotating shaft and the first slider assembly.

[0016] Furthermore, the second slider assembly includes a deep groove ball bearing, a flange bearing, and a second slider connected in sequence; the deep groove ball bearing is connected to the lead screw nut.

[0017] In one possible implementation, the variable stiffness flexible drive joint also includes an interaction module.

[0018] Furthermore, the variable stiffness drive includes variable stiffness main and auxiliary motors.

[0019] Furthermore, in the variable stiffness main and auxiliary motors, the main motor is used to drive the lead screw assembly, and the auxiliary motor is used to drive the interaction module.

[0020] The beneficial effects of the present invention are as follows:

[0021] 1. The variable stiffness flexible drive joint of the present invention includes an elastic input module and a variable stiffness module. The elastic input module includes a guide rail assembly, an elastic component, and a fixing component. The variable stiffness module includes a bracket, a lead screw assembly, a second slider assembly, and a variable stiffness actuator. Flexible variable stiffness adjustment is achieved through the integrated design and synergistic effect of the above two modules.

[0022] 2. The variable stiffness flexible drive joint described in this invention provides a new approach to humanoid joint design and can be used as a component of a robotic arm, showing great application potential. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a variable stiffness flexible drive joint structure provided in an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the flexible input module structure provided in an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the variable stiffness module structure provided in an embodiment of the present invention;

[0026] Figure 4 This is an exploded view of the elastic input module structure provided in an embodiment of the present invention;

[0027] Figure 5 This is an exploded view of the variable stiffness module structure provided in an embodiment of the present invention;

[0028] Figure 6 This is a top view of the variable stiffness module structure provided in an embodiment of the present invention;

[0029] Figure 7 This is a schematic diagram of the driving joint provided in an embodiment of the present invention;

[0030] In the attached diagram: 1. First fixed ring; 2. First fixed plate; 3. Thrust roller bearing I; 4. First guide rail; 5. Guide rail shaft; 6. First flange bearing; 7. Second guide rail; 8. Second flange bearing; 9. Second fixed plate; 10. Thrust roller bearing II; 11. Linear bearing; 12. Optical shaft; 13. Rotary bearing; 14. First spring flange; 15. Compression spring; 16. Second spring flange; 17. Optical shaft fixing flange; 18. Fixed baffle; 19. Slider rotating ring; 20. First slider; 21. Ball bearing; 22. Sidewall bearing I; 23. First deep groove ball bearing; 24. Sidewall bearing II; 25. Second slider; 26. Slider rotation shaft; 27. Deep groove ball bearing; 28. Leadscrew nut; 29. ​​Leadscrew; 30. Second deep groove ball bearing; 31. First leadscrew end fixing bracket; 32. Deep groove ball bearing; 33. Axial positioning ring; 34. 485 encoder; 35. Slider guide rail; 36. Leadscrew input fixing bracket; 37. Second output plate; 38. Variable stiffness main and auxiliary motors; 39. Second leadscrew end fixing bracket; 40. First output plate. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0034] See Figure 1 A variable stiffness flexible drive joint that can be used in humanoid robotic arms includes: an elastic input module and a variable stiffness module;

[0035] The elastic input module includes a fixing component, a guide rail component, and an elastic component; the elastic component includes an optical shaft 12 fitted with a linear bearing 11 and a spring component; the guide rail component includes a guide rail, a first slider component, and a guide rail shaft 5; one end of the guide rail is connected to the linear bearing 11 via the first slider component, and the other end is connected via the guide rail shaft 5; the fixing component is used to clamp the spring component, connects to the guide rail component via the guide rail shaft 5, and receives external power input;

[0036] The variable stiffness module includes a bracket, a lead screw assembly, a second slider assembly, and a variable stiffness driver; the lead screw assembly is fixed in the bracket, and its lead screw nut 28 is connected to the guide rail through the second slider assembly; the variable stiffness driver is used to drive the lead screw 29; the bracket is movably connected to the fixed assembly;

[0037] Driven by the fixed component, the guide rail shaft 5 causes the guide rail to rotate around the lead screw nut 28 and drive the first slider assembly to move, thereby causing the linear bearing 11 to move elastically along the optical axis 12 under the action of the compression spring 15.

[0038] In one possible implementation, see [link to relevant documentation] Figure 2 and Figure 4 The spring assembly includes a fixed baffle 18, an optical axis fixing flange 17, and a compression spring 15 connected in sequence; the fixed baffle 18 is connected to the fixing assembly; and elastic components are provided at both ends of the optical axis 12.

[0039] Furthermore, the compression spring 15 is provided with a first spring stop 14 and a second spring stop 16 at both ends.

[0040] Furthermore, the compression spring 15 remains in a compressed state throughout the entire movement.

[0041] The two compression springs 15 stabilize the linear bearing 11 in the center position; the compression springs are always in a compressed state and are equipped with two spring guards 14 and 16 to prevent them from disengaging from the axial position; the central optical axis 12 not only serves to orient the linear bearing 11, but also guides the springs, ensuring that the two compression springs do not experience instability when subjected to pressure.

[0042] In one possible implementation, the fixing component includes a first fixing ring 1, a first fixing plate 2, a second fixing ring, and a second fixing plate 9; the first fixing ring 1 is disposed on the first fixing plate 2, and the second fixing ring is disposed on the second fixing plate 9, and the two are symmetrically arranged to clamp the guide rail assembly and the elastic assembly.

[0043] Furthermore, the external power input is provided by driving the first or second fixed ring of the firmware component.

[0044] For example, see Figure 4 The first fixing ring 1 and the second fixing ring are flanges. The first fixing plate 2 and the second fixing plate 9 are fan-shaped structures, with round holes matching the fixing rings in the wide part, and a connecting plate for connecting the fixing baffle 18 is provided on the end face perpendicular to the fan surface, and holes for installing the guide rail shaft 5 are provided in the narrow part.

[0045] In one possible implementation, the first slider assembly includes a rotary bearing 13, a slider rotating ring 19, and a first slider 20 connected in sequence; the rotary bearing 13 is connected to one side of the linear bearing 11, and the first slider 20 is placed on a guide rail and can slide along the guide rail; the slider assembly is symmetrically arranged on both sides of the linear bearing 11.

[0046] Specifically, the guide rail includes a track and a protective housing, with the track housed within the protective housing.

[0047] Specifically, the guide rail shaft 5 is connected to the first fixed ring 1 and the second fixed ring in a stable and movable manner through the thrust roller bearing I 3, the first flange bearing 6, the second flange bearing 8 and the thrust roller bearing II 10.

[0048] In one possible implementation, the bracket is a square frame, with one end movably connected to a fixing component via an axial fit.

[0049] For details, see Figure 3 and Figure 5 The bracket includes a first output plate 40, a second output plate 37, a first lead screw end fixing bracket 31, a lead screw input fixing bracket 36, and a second lead screw end fixing bracket 39. The first output plate 40 and the second output plate 37 are supported by the first lead screw end fixing bracket 31, the lead screw input fixing bracket 36, and the second lead screw end fixing bracket 39, forming a square frame structure. The first lead screw end fixing bracket 31 and the lead screw input fixing bracket 36 are used to fix the lead screw, and the lead screw input fixing bracket 36 and the second lead screw end fixing bracket 39 are used to fix the variable stiffness actuator.

[0050] Specifically, the way the one end is connected to the fixed component through axial fit is as follows: the bracket and the fixed component are movably connected by setting a second deep groove ball bearing 32, an axial positioning ring 33 and a 485 encoder 34.

[0051] In one possible implementation, the lead screw assembly includes a lead screw 29 and a lead screw nut 28; the lead screw nut 28 is disposed in the guide rail, located between the guide rail shaft 5 and the first slider assembly.

[0052] Furthermore, the second slider assembly includes a deep groove ball bearing 27, a slider rotation shaft 26, and a second slider 25 connected in sequence; the deep groove ball bearing 27 is connected to a lead screw nut 28.

[0053] It should be noted that, Figure 2-5The guide rail assembly is shown in both figures to better illustrate the structure and connections. In fact, the guide rail assembly belongs to the elastic input module. Similarly, ball bearing 21, flange bearing I 22, and flange bearing II 24 are actually the same assembly as thrust roller bearing II 10, second flange bearing 8, and first flange bearing 6.

[0054] In one possible implementation, the variable stiffness flexible drive joint also includes an interaction module.

[0055] Furthermore, the variable stiffness drive includes variable stiffness main and auxiliary motors 38.

[0056] Furthermore, the interaction module includes a dexterous hand or gripper.

[0057] For details, see Figure 6 In the variable stiffness main and auxiliary motors, the main motor is used to drive the lead screw assembly, and the auxiliary motor is used to drive the interaction module.

[0058] Specifically, the variable stiffness main and auxiliary motors are two RoboMaster M3508 motors arranged in parallel.

[0059] When the variable stiffness flexible drive joint described in the embodiment is driven by an external force, it generates torque, and the whole structure will twist. Elastic potential energy is stored by a spring, and the joint stiffness is changed by adjusting the stroke of the lead screw through the variable stiffness main and auxiliary motors 38. The specific principle is as follows:

[0060] See Figure 7 Initially, without any force, the linear bearing 11 and the first slider 20 at point C are in equilibrium at point O. The screw nut 28 at point B and the second slider 25 also fall on the centerline of AO. Initially, the guide rail and the screw are aligned. When an external torque τ is applied to this structure, the entire system will twist as shown in the figure, with an overall twist angle of φ. Under the action of the torque, the guide rail, driven by the guide rail shaft 5 (point A), will rotate around point B (screw nut 28) by an angle of α. At the other end, point C (linear bearing 11) will provide axial thrust to the spring system, compressing the spring and storing energy for the elastic system. This joint achieves variable stiffness adjustment by changing the preload of the compressed spring through the auxiliary motor of the variable stiffness module driving the ball screw.

[0061] Figure 7 middle, ρ represents the relative compression of the elastic system, ρ represents the effective length of the variable stiffness input of the ball screw, and λ represents the end length of the guide lever action. This length will change slightly when the system is torn and is a variable.

[0062] When the variable stiffness flexible actuated joint (VSA) deflects, its initial potential energy and the changed potential energy are expressed as follows:

[0063]

[0064] The double compression spring system can be considered as two springs connected in parallel, producing a stiffness of 2k. In the above formula... Assume the initial elastic potential energy of the elastic system is 0 in the initial state. This represents the elastic potential energy stored in the VSA when the VSA twist angle is φ.

[0065] The first derivative of the total elastic potential energy stored in the VSA with respect to the torsional angle is the output torque of the system, and the second derivative is the torsional stiffness of the VSA. The expressions for the torque and stiffness of the VSA are as follows:

[0066]

[0067] in, Indicates the torque of VSA. This indicates the stiffness of the VSA.

[0068] Analytical expression for the stiffness of a VSA variable stiffness flexible actuator:

[0069]

[0070] in, Indicates the spring compression stroke. This indicates the distance from the linear bearing to the initial position of the guide rail shaft.

[0071] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the invention.

Claims

1. A variable stiffness flexible drive joint that can be used in a humanoid robotic arm, characterized in that, include: Elastic input module and variable stiffness module; The elastic input module includes a fixing component, a guide rail component, and an elastic component; the elastic component includes an optical shaft fitted with a linear bearing and a spring component; the guide rail component includes a guide rail, a first slider component, and a guide rail shaft; one end of the guide rail is connected to the linear bearing via the first slider component, and the other end is connected via the guide rail shaft; the fixing component is used to clamp the spring component, connects to the guide rail component via the guide rail shaft, and receives external power input; The variable stiffness module includes a bracket, a lead screw assembly, a second slider assembly, and a variable stiffness driver; the lead screw assembly is fixed in the bracket, and its lead screw nut is connected to the guide rail through the second slider assembly; the variable stiffness driver is used to drive the lead screw; the bracket is movably connected to the fixed assembly; the lead screw assembly includes a lead screw and a lead screw nut; the lead screw nut is disposed in the guide rail, located between the rotating shaft and the first slider assembly; Driven by the fixed component, the guide rail shaft rotates around the lead screw nut and drives the first slider assembly to move, thereby causing the linear bearing to move elastically along the optical axis under the action of the spring.

2. The variable stiffness flexible drive joint for use in humanoid robotic arms according to claim 1, characterized in that, The spring assembly includes a fixed baffle, an optical axis fixing flange, and a compression spring connected in sequence; the fixed baffle is connected to the fixing assembly; and elastic components are provided at both ends of the optical axis.

3. The variable stiffness flexible drive joint for use in humanoid robotic arms according to claim 1, characterized in that, The fixing component includes a first fixing ring, a first fixing plate, a second fixing ring, and a second fixing plate; the first fixing ring is disposed on the first fixing plate, and the second fixing ring is disposed on the second fixing plate, and the two are symmetrically arranged to clamp the guide rail assembly and the elastic component.

4. The variable stiffness flexible drive joint for use in humanoid robotic arms according to claim 3, characterized in that, The external power input is achieved by driving the first or second fixed ring of the firmware component to input power.

5. The variable stiffness flexible drive joint for use in humanoid robotic arms according to claim 1, characterized in that, The first slider assembly includes a rotating bearing, a slider rotating ring, and a first slider connected in sequence; the rotating bearing is connected to one side of the linear bearing; the first slider is placed on a guide rail and can slide along the guide rail; the slider assembly is symmetrically arranged on both sides of the linear bearing.

6. The variable stiffness flexible drive joint for use in humanoid robotic arms according to claim 1, characterized in that, The bracket is a square frame, with one end movably connected to the fixing component via an axial fit.

7. The variable stiffness flexible drive joint for use in humanoid robotic arms according to claim 1, characterized in that, The second slider assembly includes a deep groove ball bearing, a flange bearing, and a second slider connected in sequence; the deep groove ball bearing is connected to the lead screw nut.

8. The variable stiffness flexible drive joint for use in humanoid robotic arms according to claim 1, characterized in that, The variable stiffness flexible drive joint also includes an interaction module.

9. The variable stiffness flexible drive joint for use in humanoid robotic arms according to claim 8, characterized in that, The variable stiffness actuator includes variable stiffness main and auxiliary motors; in the variable stiffness main and auxiliary motors, the main motor is used to drive the lead screw assembly, and the auxiliary motor is used to drive the interaction module.

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