A variable stiffness robot joint

Abstract

The present invention provides a variable stiffness robot joint, including a variable stiffness mechanism; the variable stiffness mechanism includes a housing, a transmission shaft, an elastic beam and a sliding member, the transmission shaft is rotatably arranged in the housing, one end of the elastic beam is connected to the transmission shaft, the other end of the elastic beam extends in a direction away from the axis of the transmission shaft and is a free end, the sliding member can be slidably mounted on the elastic beam, and the sliding member is connected to the housing, when the force of the housing acting on the sliding member reaches a preset degree, the sliding member is used to slide along the elastic beam to change the effective length of the elastic beam, thereby changing the stiffness of the robot joint. The present invention aims to provide a variable stiffness robot joint that can change stiffness without a driving device.

Description

Technical Field

[0001] The invention relates to the field of variable stiffness joints of robots, and in particular to a variable stiffness robot joint. Background Art

[0002] With the continuous development of robot technology, the scope of robot application is becoming more and more extensive, and there are more and more scenes of human-machine interaction. In order to ensure the safety of workers and reduce the occurrence of accidents in the process of human-machine collaborative work, there is an urgent need for a robot system that can be used in a human-machine collaborative environment and is environmentally friendly and safe for workers. However, in the research of joint robots such as industrial robot arms, bionic multi-legged robots, mechanical exoskeletons, and rehabilitation medical prostheses, the design of robot joints generally adopts a driving method in which the motor output shaft is rigidly connected to the joint mechanism. This rigid connection method makes the joint have no buffer when it is impacted, and the acceleration is large, which is very easy to cause damage to the robot or the person.

[0003] The following phenomenon was found in the study of human walking: before the swing leg lands, the leg muscles relax to absorb the impact, and after the swing leg lands, the leg muscles contract to maintain balance during the double-foot support. Through this mechanism, humans can effectively reduce the impact and maintain stability during fast walking and running. Variable stiffness joints can make the robot system, like human muscles, change the stiffness appropriately when encountering impact, thereby buffering the energy generated by the collision and protecting the machine and personnel. Therefore, the study of joints with variable stiffness has become a hot topic in robots, which can promote the development of industrial, multi-legged, exoskeleton, prosthetic and other robotic fields. The Chinese invention patent application with publication number CN206561438U discloses a robot flexible joint with continuously adjustable stiffness based on a spring leaf. However, this structure requires a driving device to change the stiffness, has a slow response speed and a complex structure. As robots and humans come into closer contact, improving the safety of human-machine interaction becomes the primary factor in future robot design. This requires that the robot's variable stiffness joints cannot be limited to the above-mentioned structural form. Another structural form of the variable stiffness joint needs to be designed to absorb external impacts, protect the joints and the human body, and enable the joints to change stiffness without being driven. Summary of the invention

[0004] The main object of the present invention is to provide a variable stiffness robot joint that can change stiffness without driving.

[0005] To achieve the above-mentioned purpose, the variable stiffness robot joint proposed in the present invention includes a variable stiffness mechanism; including a variable stiffness mechanism; the variable stiffness mechanism includes a shell, a transmission shaft, an elastic beam and a sliding member, the transmission shaft is rotatably arranged in the shell, one end of the elastic beam is connected to the transmission shaft, and the other end of the elastic beam extends in a direction away from the axis of the transmission shaft and is a free end, the sliding member can be slidably mounted on the elastic beam, and the sliding member is connected to the shell, when the force of the shell acting on the sliding member reaches a preset level, the sliding member is used to slide along the elastic beam to change the effective length of the elastic beam, thereby changing the stiffness of the robot joint.

[0006] Preferably, the shell includes a cylinder and a cover plate, the axis of the cylinder is colinear with the axis of the transmission shaft, the cover plate is arranged at either end of the cylinder, and an opening is arranged at the end of the cylinder without the cover plate to allow the transmission shaft to penetrate into the internal space of the cylinder.

[0007] Preferably, the sliding member includes a guiding element and a sliding element, the sliding element is sleeved on the guiding element, the guiding direction of the guiding element is away from the transmission shaft, one end of the guiding element is connected to the side wall of the cylinder, and the other end extends toward the transmission shaft, the sliding element is sleeved on the elastic beam and can slide along the guiding direction, and the sliding element can change its stiffness when sliding along the guiding direction.

[0008] Preferably, the sliding element comprises a support seat and a roller, the support seat is a hollow structure, and the roller is arranged in the support seat and fits on both sides of the elastic beam to roll with the elastic beam.

[0009] Preferably, the sliding element further comprises a sliding unit, the cover plate is provided with an arc-shaped slideway, one end of the arc-shaped slideway faces the transmission shaft, and the other end faces the side wall of the cylinder, the sliding unit is connected to a support seat, and the sliding unit slides in cooperation with the slideway.

[0010] Preferably, the arc-shaped slideway comprises a locking section and a variable stiffness section, the locking section is used to lock the sliding element through an arc-shaped direction, and the variable stiffness section is used to guide the sliding element to slide away from the transmission shaft.

[0011] Preferably, it further comprises a driving mechanism and a control mechanism, wherein the driving mechanism is connected to the transmission shaft to transmit torque to the transmission shaft, and the control mechanism is arranged at one end of the driving mechanism away from the variable stiffness mechanism to control the rotation of the driving mechanism.

[0012] Preferably, an output end is formed on an outer wall of one end of the housing away from the driving mechanism, and the output end is used to be connected to an external torque transmission structure.

[0013] Preferably, the elastic beams and sliding members are provided in a plurality of groups and in corresponding numbers, and the plurality of groups of elastic beams and the plurality of groups of sliding members are arranged around the transmission shaft.

[0014] Preferably, a plurality of the arc-shaped slideways are provided, the number of which corresponds to the elastic beam, and the plurality of arc-shaped slideways are connected to each other toward one end of the transmission shaft.

[0015] To sum up, the present invention proposes a variable stiffness robot joint, which is provided with a variable stiffness mechanism; when the joint is impacted, the impact force causes the shell of the variable stiffness mechanism to rotate, and the arc-shaped slideway and the sliding element arranged on the shell are in a locked state, driving the sliding element and the elastic beam connected to the sliding element to rotate together; when the impact force is too large, the locking of the arc-shaped slideway and the sliding element fails, and the sliding element slides along the arc-shaped slideway away from the direction of the transmission shaft, changing the effective working length of the elastic beam, thereby achieving the effect of changing the stiffness. The technical solution proposed in the present invention can change the stiffness without driving. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0017] Figure 1 It is a schematic diagram of the external structure of an embodiment of a variable stiffness robot joint of the present invention;

[0018] Figure 2 This is a schematic diagram of the variable stiffness structure of the variable stiffness robot joint of the present invention;

[0019] Figure 3 This is a schematic diagram of the cooperation of the variable stiffness robot joint sliding parts of the present invention;

[0020] Figure 4 This is a schematic diagram of the structure of the variable stiffness robot joint sliding member of the present invention;

[0021] Figure 5 for Figure 4 An enlarged schematic diagram of the sliding member structure;

[0022] Figure 6 It is a schematic diagram of the bottom surface of the variable stiffness robot joint of the present invention;

[0023] Figure 7 It is a side view schematic diagram of the variable stiffness robot joint of the present invention;

[0024] Figure 8It is a cross-sectional schematic diagram of the joint of the variable stiffness robot of the present invention;

[0025] Fig. 9 It is a schematic diagram of the top surface of the variable stiffness robot joint of the present invention;

[0026] Fig.10 This is a schematic diagram of the variable stiffness robot joint arc slide structure of the present invention.

[0027] Description of Figure Numbers:

[0028] 1-variable stiffness mechanism; 2-driving mechanism; 3-control mechanism; 11-housing; 12-transmission shaft; 13-elastic beam; 14-sliding member; 15-arc slideway; 111-cylinder; 112-cover plate; 141-guiding element; 142-sliding element; 142a-support seat; 142b-roller; 142c-sliding unit; 21-driving motor; 31-encoder; 32-control board.

[0029] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0030] 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.

[0031] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0032] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0033] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0035] The invention provides a variable stiffness robot joint.

[0036] Please refer to Figures 1 to 10 The variable stiffness robot joint includes the variable stiffness robot joint proposed by the present invention, including a variable stiffness mechanism 1; the variable stiffness mechanism 1 includes a shell 11, a transmission shaft 12, an elastic beam 13 and a sliding member 14, the transmission shaft 12 is rotatably arranged in the shell 11, one end of the elastic beam 13 is connected to the transmission shaft 12, and the other end of the elastic beam 13 extends in a direction away from the axis of the transmission shaft 12 and is a free end, the sliding member 14 can be slidably mounted on the elastic beam 13, and the sliding member 14 is connected to the shell 11. When the force of the shell 11 acting on the sliding member 14 reaches a preset degree, the sliding member 14 is used to slide along the elastic beam 13 to change the effective length of the elastic beam 13, thereby changing the stiffness of the robot joint. In one embodiment of the present invention, the elastic beam 13 is a nickel-titanium alloy elastic sheet, and the shell 11 is a metal structural member.

[0037] In summary, when the joint is impacted, the impact force causes the shell 11 of the variable stiffness mechanism 1 to rotate, and the arcuate slide 15 provided on the shell 11 is in a locked state with the sliding element 142, driving the sliding element 142 and the elastic beam 13 connected to the sliding element 142 to rotate together; when the impact force is too large, the locking of the arcuate slide 15 and the sliding element 142 fails, and the sliding element 142 slides along the arcuate slide 15 in a direction away from the transmission shaft 12, changing the effective working length of the elastic beam 13, thereby achieving the effect of changing the stiffness. The technical solution proposed in the present invention can change the stiffness without driving.

[0038] Preferably, the housing 11 includes a cylinder 111 and a cover plate 112, the axis of the cylinder 111 is colinear with the axis of the transmission shaft 12, the cover plate 112 is arranged at either end of the cylinder 111, and an opening is arranged at the end of the cylinder 111 not provided with the cover plate 112 to allow the transmission shaft 12 to penetrate into the internal space of the cylinder 111. In this embodiment, the cylinder 111 is a cylinder, the cover plate 112 is a circular plate, and the cylinder 111 and the cover plate 112 are fixedly connected by bolts.

[0039] Preferably, the sliding member 14 includes a guiding element 141 and a sliding element 142, wherein the sliding element 142 is sleeved on the guiding element 141, the guiding direction of the guiding element 141 is away from the transmission shaft 12, one end of the guiding element 141 is connected to the side wall of the cylinder 111, and the other end extends toward the transmission shaft 12, the sliding element 142 is sleeved on the elastic beam 13 and can slide along the guiding direction, and the sliding element 142 can change its stiffness when sliding along the guiding direction. In this embodiment, the guiding element 141 is a linear guide beam, and the base of the support frame is slidably matched with the linear guide beam.

[0040] like Figure 4 As shown, the sliding element 142 includes a support seat 142a and a roller 142b, the support seat 142a is a hollow structure, and the roller 142b is arranged in the support seat 142a, and is fitted on both sides of the elastic beam 13 and rolls with the elastic beam 13. In this embodiment, the support seat 142a is provided with a base and an upper beam, and the base and the upper beam are fixedly connected by two connecting rods, and two rollers 142b are provided, and the two ends of the roller 142b are respectively roll-connected with the base of the support seat 142a and the upper beam.

[0041] Preferably, the sliding element 142 further includes a sliding unit 142c, the cover plate 112 is provided with an arc-shaped slideway 15, one end of the arc-shaped slideway 15 faces the transmission shaft 12, and the other end faces the side wall of the cylinder 111, the sliding unit 142c is connected to the support seat 142a, and the sliding unit 142c slides in cooperation with the slideway. In this embodiment, the sliding unit 142c is a roller, one roller is provided, one end of the roller is rollingly connected to the upper beam of the support seat 142a, and the other end is sleeved in the arc-shaped slideway 15.

[0042] Preferably, the arcuate slideway 15 includes a locking section and a variable stiffness section, wherein the locking section is used to lock the sliding element 142 through an arcuate direction, and the variable stiffness section is used to guide the sliding element 142 to slide away from the transmission shaft 12. When the joint rotates, a force is generated between the sliding element and the arcuate slideway. When the force is less than a preset value, the sliding unit 142c is locked and matched with the arcuate slideway 15. When the force is greater than a preset value, the sliding unit 142c escapes from the locking section and slides along the variable stiffness section in a direction away from the transmission shaft 12.

[0043] Preferably, it further includes a driving mechanism 2 and a control mechanism 3, wherein the driving mechanism 2 is connected to the transmission shaft 12 to transmit torque to the transmission shaft 12, and the control mechanism 3 is arranged at one end of the driving mechanism 2 away from the variable stiffness mechanism 1, and is used to control the rotation of the driving mechanism 2. In this embodiment, the driving mechanism 2 is a driving motor 21, and the control mechanism 3 includes an encoder 21 and a control board 32, wherein the encoder 21 is used to measure the rotation angle of the driving motor 21, and the control board 32 is electrically connected to the encoder 21 to control the rotation of the driving motor 21. The coordination of the control board, the encoder and the driving motor is a prior art and will not be described in detail here.

[0044] Preferably, an output end is formed on the outer wall of one end of the housing 11 away from the driving mechanism 2, and the output end is used to connect with an external torque transmission structure. In this embodiment, the output end is formed on a side of the cover plate 112 away from the transmission shaft 12, and the output end is connected to an external mechanical arm or connecting rod through bolts to transmit torque to the outside.

[0045] Preferably, the elastic beams 13 and the sliding members 14 are provided in multiple groups and the number thereof corresponds, and the multiple groups of elastic beams 13 and the multiple groups of sliding members 14 are arranged around the transmission shaft 12. In this embodiment, the number of the elastic beams 13 and the sliding members 14 are both set to 4 groups, which are evenly arranged around the transmission shaft 12. Of course, the number of the elastic beams and the sliding members is not limited thereto, and those skilled in the art can adjust them as needed.

[0046] Preferably, the arc-shaped slideways 15 are provided in plurality, the number of which corresponds to the elastic beam 13, and the arc-shaped slideways 15 are connected to each other at one end facing the transmission shaft 12. In this embodiment, the arc-shaped slideways 15 are provided in four pieces, which are evenly and symmetrically formed in an X shape on one side of the cover plate 112 facing the transmission shaft 12.

[0047] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A variable stiffness robot joint, characterized in that: It includes a variable stiffness mechanism; the variable stiffness mechanism includes a shell, a transmission shaft, an elastic beam and a sliding member, the transmission shaft is rotatably arranged in the shell, one end of the elastic beam is connected to the transmission shaft, the other end of the elastic beam extends in a direction away from the axis of the transmission shaft and is a free end, the sliding member can be slidably mounted on the elastic beam, and the sliding member is connected to the shell, when the force of the shell acting on the sliding member reaches a preset degree, the sliding member is used to slide along the elastic beam to change the effective length of the elastic beam, thereby changing the stiffness of the robot joint.

2. The variable stiffness robot joint according to claim 1, characterized in that: The shell includes a cylinder and a cover plate, the axis of the cylinder is colinear with the axis of the transmission shaft, the cover plate is arranged at either end of the cylinder, and an opening is arranged at the end of the cylinder where the cover plate is not arranged to allow the transmission shaft to penetrate into the internal space of the cylinder.

3. The variable stiffness robot joint according to claim 2, characterized in that: The sliding member includes a guiding element and a sliding element, wherein the sliding element is sleeved on the guiding element, the guiding direction of the guiding element is away from the transmission shaft, one end of the guiding element is connected to the side wall of the cylinder, and the other end extends toward the transmission shaft, the sliding element is sleeved on the elastic beam and can slide along the guiding direction, and the sliding element can change its stiffness when sliding along the guiding direction.

4. The variable stiffness robot joint according to claim 3, characterized in that: The sliding element comprises a support seat and a roller. The support seat is a hollow structure. The roller is arranged in the support seat and fits on both sides of the elastic beam to roll with the elastic beam.

5. The variable stiffness robot joint according to claim 3, characterized in that: The sliding element also includes a sliding unit. The cover plate is provided with an arc-shaped slideway, one end of the arc-shaped slideway faces the transmission shaft, and the other end faces the side wall of the cylinder. The sliding unit is connected to a support seat, and the sliding unit slides in cooperation with the slideway.

6. The variable stiffness robot joint according to claim 5, characterized in that: The arc-shaped slideway includes a locking section and a variable stiffness section, wherein the locking section is used to lock the sliding element through an arc-shaped direction, and the variable stiffness section is used to guide the sliding element to slide away from the transmission shaft.

7. The variable stiffness robot joint according to claim 6, characterized in that: It also includes a driving mechanism and a control mechanism. The driving mechanism is connected to the transmission shaft to transmit torque to the transmission shaft. The control mechanism is arranged at one end of the driving mechanism away from the variable stiffness mechanism to control the rotation of the driving mechanism.

8. The variable stiffness robot joint according to claim 7, characterized in that: An output end is formed on an outer wall of one end of the housing away from the driving mechanism, and the output end is used to be connected to an external torque transmission structure.

9. The variable stiffness robot joint according to claim 8, characterized in that: The elastic beams and sliding members are provided in a plurality of groups and in corresponding numbers, and the plurality of groups of elastic beams and the plurality of groups of sliding members are arranged around the transmission shaft.

10. The variable stiffness robot joint according to any one of claims 5 to 9, characterized in that: The arc-shaped slideways are provided in plurality, the number of which corresponds to the elastic beams, and the arc-shaped slideways are connected to each other toward one end of the transmission shaft.

Images