Variable-rigidity flexible driving joint capable of being used for humanoid mechanical arm

Abstract

The invention discloses a variable-rigidity flexible driving joint capable of being used for a humanoid mechanical arm. The variable-rigidity flexible driving joint comprises an elastic input module and a variable-rigidity module. The elastic input module comprises a fixing assembly, a guide rail assembly and an elastic assembly; the elastic assembly comprises an optical shaft sleeved with a linear bearing and a spring assembly. The guide rail assembly comprises a guide rail, a first sliding block assembly and a guide rail rotating shaft. One end of the guide rail is connected with the linear bearing through the first sliding block assembly, and the other end is connected through the guide rail rotating shaft; the variable stiffness module comprises a support, a lead screw assembly, a second sliding block assembly and a variable stiffness driver. The guide rail rotating shaft is driven by the fixing assembly, so that the guide rail rotates around the lead screw nut and drives the first sliding block assembly to move, and then the linear bearing elastically moves along the optical axis under the action of the spring. According to the driving joint, flexible variable rigidity adjustment is achieved, a new thought is provided for humanoid joint design, and the driving joint can be used as one of components of a mechanical arm and has a large application prospect.

Description

Technical Field

[0001] The invention proposes a variable stiffness flexible driving joint, belongs to the technical field of robots, and particularly relates to a variable stiffness flexible driving joint that can be used for a humanoid robot arm. Background Art

[0002] Humanoid robotic arms can be divided into rigid humanoid robotic arms and flexible humanoid robotic arms according to the type of their driving joints. In the working environment where human-machine interaction requires higher requirements, flexible humanoid robotic arms have greater potential. Humans and animals can use their muscles or tissue elasticity to store and release energy during movement; adjust energy distribution, increase the instantaneous explosive force of joints, and also play a buffering and protective role when subjected to external impacts. Therefore, the design technology of bionic driving joints is the difficulty of robots.

[0003] Compared with traditional rigid actuators, flexible joints can provide high robustness, task adaptability and safety against external interference. Moreover, when interacting with humans or complex environments, this high robustness, strong task adaptability and low impedance can more effectively handle such unknown contact forces. Therefore, taking bionic drive as the key to research breakthroughs, developing variable stiffness actuators with flexible driving capabilities 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 the present invention is to solve the problems existing in the background technology and to provide a variable stiffness flexible drive joint that can be used for a humanoid robot arm.

[0005] The technical solution provided by the present invention is as follows:

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

[0007] The elastic input module includes a fixed component, a guide rail component and an elastic component; the elastic component includes an optical axis with a linear bearing and a spring component; the guide rail component includes a guide rail, a first slider component and a guide rail rotating shaft; one end of the guide rail is connected to the linear bearing through the first slider component, and the other end is connected through the guide rail rotating shaft; the fixed component is used to clamp the spring component, connect the guide rail component through the guide rail rotating shaft and receive external input power;

[0008] The variable stiffness module comprises 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] The guide rail rotating shaft is driven by the fixing assembly so that the guide rail 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 a possible implementation, the spring assembly includes a fixed baffle, an optical axis fixing flange and a spring which are connected in sequence; the fixed baffle is connected to the fixing assembly; and elastic assemblies are provided at both ends of the optical axis.

[0011] In one possible implementation, the fixing assembly includes a first fixing ring, a first fixing plate, a second fixing ring and a second fixing plate; the first fixing ring is arranged on the first fixing plate, and the second fixing ring is arranged 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 input through the first fixing ring or the second fixing ring of the driving fixture assembly.

[0013] In one possible implementation, 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.

[0014] In one possible implementation, the bracket is a square frame, one end of which is movably connected to the fixing assembly through axial fit.

[0015] In one possible implementation, the screw assembly includes a screw and a screw nut; the screw nut is arranged in the 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 which are 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 further 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 screw assembly, and the auxiliary motor is used to drive the interactive module.

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

[0021] 1. The variable stiffness flexible drive joint of the present invention comprises an elastic input module and a variable stiffness module, wherein the elastic input module comprises a guide rail assembly, an elastic assembly and a fixing assembly, and the variable stiffness module comprises a bracket, a lead screw assembly, a second slider assembly and a variable stiffness driver. The flexible variable stiffness adjustment is realized by utilizing the integrated design and synergistic effect of the above two modules.

[0022] 2. The variable stiffness flexible drive joint of the present invention provides a new idea for the design of humanoid joints and can be used as one of the components of a robotic arm, thus having great application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0024] Figure 2 A schematic diagram of the structure of an elastic input module provided in an embodiment of the present invention;

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

[0026] Figure 4 An exploded schematic diagram of the elastic input module structure provided in an embodiment of the present invention;

[0027] Figure 5 An exploded schematic diagram of a variable stiffness module structure provided in an embodiment of the present invention;

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

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

[0030] In the attached drawings: 1, first fixing ring; 2, first fixing plate; 3, thrust roller bearing I; 4, first guide rail; 5, guide rail rotating shaft; 6, first flange bearing; 7, second guide rail; 8, second flange bearing; 9, second fixing plate; 10, thrust roller bearing II; 11, linear bearing; 12, optical axis; 13, rotating bearing; 14, first spring flange; 15, compression spring; 16, second spring flange; 17, optical axis fixing flange; 18, fixing baffle; 19, slider rotating ring; 20, first slider; 21, ball bearing; 22. Flange bearing I; 23. First deep groove ball bearing; 24. Flange bearing II; 25. Second slider; 26. Slider rotating shaft; 27. Deep groove ball bearing; 28. Screw nut; 29. ​​Screw; 30. Second deep groove ball bearing; 31. First screw end fixing bracket; 32. Deep groove ball bearing; 33. Axial positioning ring; 34. 485 encoder; 35. Slider guide rail; 36. Screw input fixing bracket; 37. Second output plate; 38. Variable stiffness main and auxiliary motors; 39. Second screw end fixing bracket; 40. First output plate. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work 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 in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0034] See also Figure 1 , a variable stiffness flexible drive joint that can be used for a humanoid robot arm, comprising: an elastic input module and a variable stiffness module;

[0035] The elastic input module includes a fixed component, a guide rail component and an elastic component; the elastic component includes an optical axis 12 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 rotating shaft 5; one end of the guide rail is connected to the linear bearing 11 through the first slider component, and the other end is connected through the guide rail rotating shaft 5; the fixed component is used to clamp the spring component, connect the guide rail component through the guide rail rotating shaft 5 and receive external input power;

[0036] The variable stiffness module comprises 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] The guide rail rotating shaft 5 is driven by the fixing assembly so that the guide rail rotates around the lead screw nut 28 and drives the first slider assembly to move, thereby causing the linear bearing 11 to elastically move along the optical axis 12 under the action of the spring 15 .

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

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

[0040] Furthermore, the spring 15 is in a compressed state during the entire movement process.

[0041] The two compression springs 15 stabilize the linear bearing 11 in the center position; the compression spring is always in a compressed state, and is provided with two spring retaining edges 14 and 16 to prevent it from deviating from the axial position; the central optical axis 12 not only plays a directional role for the linear bearing 11, but also serves as a spring guide to ensure that the two compression springs will not cause the compression rod to become unstable when subjected to pressure.

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

[0043] Furthermore, the external input power is input through the first fixing ring 1 or the second fixing ring 2 of the driving firmware component.

[0044] For example, see Figure 4 The first fixing ring 17 and the second fixing ring are flanges. The first fixing plate 18 and the second fixing plate 9 are fan-shaped structures, with a round hole matching the fixing ring in the wide part, a connecting plate for connecting the fixing baffle 18 is arranged on the end surface perpendicular to the fan surface, and a hole is opened in the narrow part for installing the guide rail shaft 5.

[0045] In one possible implementation, the first slider assembly includes a rotating bearing 13, a slider rotating ring 19 and a first slider 20 connected in sequence; the rotating 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 shell, and the track is placed in the protective shell.

[0047] Specifically, the guide rail shaft 5 forms a stable and movable connection with the first fixing ring 2 and the second fixing ring 25 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, one end of which is movably connected to the fixing assembly through 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 screw end fixing frame 31, a screw input fixing frame 36 and a second screw end fixing frame 39. The first output plate 40 and the second output plate 37 are supported by the first screw end fixing frame 31, the screw input fixing frame 36 and the second screw end fixing frame 39 to form a square frame structure. The first screw end fixing frame 31 and the screw input fixing frame 36 are used to fix the screw, and the screw input fixing frame 36 and the second screw end fixing frame 39 are used to fix the variable stiffness driver.

[0050] Specifically, the one end is connected to the fixed assembly through axial cooperation in the following manner: a second deep groove ball bearing 32 , an axial positioning ring 33 and a 485 encoder 34 are provided to realize a movable connection between the bracket and the fixed assembly.

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

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

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

[0054] In one possible implementation, the variable stiffness flexible drive joint further 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 a gripper.

[0057] For details, see Figure 6 In the variable stiffness main and auxiliary motors, the main motor is used to drive the screw assembly, and the auxiliary motor is used to drive the interactive 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, torque is generated and the whole body will be twisted, wherein elastic potential energy is stored by the spring, and the variable stiffness main and auxiliary motors 38 are used to adjust the screw rod stroke to change the joint stiffness. The specific principle is as follows:

[0060] See also Figure 7 , when no force is applied initially, the linear bearing 11 and the first slider 20 at point C are at equilibrium at point O, and the lead screw nut 28 and the second slider 25 at point B also fall on the center line AO. In the figure, the guide rail and the lead screw are initially in an overlapping state. When an external force torque τ is applied to this structure, the entire system will be twisted as shown in the figure, and the overall twist angle is Under the action of torque, the guide rail, driven by the guide rail shaft 5 (point A), will rotate around point B (screw nut 28) at an angle of α. The other end, point C (linear bearing 11), will provide axial thrust to the spring system, compress the spring, and store energy for the elastic system. The joint changes the preload of the compression spring through the auxiliary motor of the variable stiffness module to achieve variable stiffness adjustment.

[0061] Figure 7 In, l OC represents the relative compression of the elastic system, ρ represents the effective length of the variable stiffness of the ball screw input, and λ represents the end length of the guide rail lever, which will produce a small change when the system is twisted 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:

[0063]

[0064] The double compression spring system can be regarded as two parallel springs, and the resulting stiffness is 2k. VSA0 Assume that the initial elastic potential energy of the elastic system is 0 in the initial state, E VSAs It is expressed as the torsion angle of VSA is In this case, the elastic potential energy stored in VSA.

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

[0066]

[0067] Among them, τ VSAex represents the torque of VSA, k VSAex Represents the stiffness of the VSA.

[0068] The stiffness analytical expression of VSA variable stiffness flexible actuator is:

[0069]

[0070] Among them, l OC Indicates the spring compression stroke, l AO Indicates the distance of the linear bearing at the initial position of the guide shaft.

[0071] The above description is only a preferred specific implementation manner 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 any technician familiar with the technical field within the technical scope disclosed by the present invention should be included in the scope of protection of the invention.

Claims

1. A variable stiffness flexible drive joint that can be used for a humanoid robot arm, characterized in that: include: Elastic input module and 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 with a linear bearing and a spring component; the guide rail component includes a guide rail, a first slider component and a guide rail rotating shaft; one end of the guide rail is connected to the linear bearing through the first slider component, and the other end is connected through the guide rail rotating shaft; the fixed component is used to clamp the spring component, connect the guide rail component through the guide rail rotating shaft and receive external input power; The variable stiffness module comprises 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 guide rail rotating shaft is driven by the fixing assembly so that the guide rail 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 applicable to a humanoid robot arm according to claim 1, characterized in that: The spring assembly comprises a fixed baffle, an optical axis fixing flange and a spring which are connected in sequence; the fixed baffle is connected to the fixing assembly; and elastic assemblies are arranged at both ends of the optical axis.

3. The variable stiffness flexible drive joint applicable to a humanoid robot arm according to claim 1, characterized in that: The fixing assembly includes a first fixing ring, a first fixing plate, a second fixing ring and a second fixing plate; the first fixing ring is arranged on the first fixing plate, and the second fixing ring is arranged on the second fixing plate, and the two are symmetrically arranged for clamping the guide rail assembly and the elastic assembly.

4. The variable stiffness flexible drive joint applicable to a humanoid robot arm according to claim 3, characterized in that: The external power input is input through the first fixed ring or the second fixed ring of the driving fixture assembly.

5. The variable stiffness flexible drive joint applicable to a humanoid robot arm 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 the 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 applicable to a humanoid robot arm according to claim 1, characterized in that: The bracket is a square frame, one end of which is movably connected to the fixing component through axial cooperation.

7. The variable stiffness flexible drive joint applicable to a humanoid robot arm according to claim 1, characterized in that: The lead screw assembly comprises a lead screw and a lead screw nut; the lead screw nut is arranged in the guide rail, between the rotating shaft and the first slider assembly.

8. The variable stiffness flexible drive joint applicable to a humanoid robot arm according to claim 7, characterized in that: The second slider assembly includes a deep groove ball bearing, a flange bearing and a second slider which are connected in sequence; the deep groove ball bearing is connected to the lead screw nut.

9. The variable stiffness flexible drive joint applicable to a humanoid robot arm according to claim 1, characterized in that: The variable stiffness flexible drive joint also includes an interaction module.

10. The variable stiffness flexible drive joint applicable to a humanoid robot arm according to claim 9, characterized in that: The variable stiffness driver comprises a 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 interactive module.

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