CN114654496B

CN114654496B - Active rigidity-variable rotary joint based on involute leaf spring

Info

Publication number: CN114654496B
Application number: CN202210333631.XA
Authority: CN
Inventors: 梁杰俊一; 刘阳; 孙晨露; 汪涛; 程坤华; 严禹; 邓亦骁; 王淑敏; 熊蔡华
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2022-03-30
Filing date: 2022-03-30
Publication date: 2023-08-25
Anticipated expiration: 2042-03-30
Also published as: CN114654496A

Abstract

The application belongs to the technical field related to variable stiffness joint design, and discloses an active variable stiffness rotary joint based on an involute leaf spring, which comprises the following components: the motor driving module comprises a central shaft, an upper joint bottom plate and an upper joint connecting plate; the involute leaf spring module comprises a leaf spring fixing piece and a plurality of involute leaf springs; the variable stiffness pressure spring roller modules are arranged in parallel with the central shaft and are uniformly arranged between the two upper joint bottom plates; the linear bearing driving module comprises a variable-rigidity external gear, a variable-rigidity mechanism bearing and a plurality of guide rods; the central shaft rotary output module comprises two lower joint bottom plates and a lower joint connecting plate, a plurality of through involute channels are arranged on the surfaces of the lower joint bottom plates, and two ends of the variable stiffness pressure spring roller module are respectively arranged in the involute channels. The application designs the leaf spring through the special property of the involute, can realize a large rigidity change range, has simple rigidity change control and small whole joint volume and weight.

Description

Active rigidity-variable rotary joint based on involute leaf spring

Technical Field

The application belongs to the technical field related to variable stiffness joint design, and particularly relates to an active variable stiffness rotary joint based on an involute leaf spring.

Background

With the continuous improvement of the international science level, in the field of humanoid robots or prosthetic arms, flexible joints are a research hotspot, and have the functions of relieving collision, avoiding damage, accumulating energy, changing force output characteristics at any time and the like. The current solution is convenient: the elastic element is connected in series, but the rigidity of the elastic element is unchanged, namely, the elastic element only plays a role of an elastic driver; the magneto-rheological or electrorheological medium is introduced for control, but the liquid characteristics need to be completely researched; pneumatic muscle models are utilized, but the device is too bulky; shape memory alloys are utilized but do not allow the stiffness to be varied at any time with their own requirements. The existing device for designing the rigidity change of the single-degree-of-freedom rotary joint mostly adopts antagonism type in the field of active rigidity change, and has the defects of large control difficulty, large motor volume, large weight and small rigidity change range of the whole joint.

Disclosure of Invention

Aiming at the defects or improvement demands of the prior art, the application provides the active variable stiffness rotary joint based on the involute leaf spring, and the leaf spring can be designed through the special property of the involute, so that the large stiffness change range can be realized, the stiffness change control is simple, and the whole joint is small in volume and weight.

In order to achieve the above object, according to one aspect of the present application, there is provided an active variable stiffness rotary joint based on an involute leaf spring, the joint including a motor driving module, an involute leaf spring module, a plurality of variable stiffness pressure spring roller modules, a linear bearing driving module, and a central shaft rotation output module, wherein: the motor driving module comprises a central shaft, an upper joint bottom plate and an upper joint connecting plate, wherein two ends of the central shaft are respectively connected with the upper joint bottom plate through bearings, a motor driving assembly is arranged on one upper joint bottom plate and used for driving the central shaft to rotate, the upper joint connecting plate is U-shaped, and two sides of the U-shaped upper joint bottom plate are respectively connected with the upper joint bottom plate; the involute leaf spring module comprises a leaf spring fixing piece and a plurality of involute leaf springs, one ends of the involute leaf springs are uniformly fixed on the leaf spring fixing piece, and the leaf spring fixing piece is sleeved and fixed on the central shaft; the variable stiffness pressure spring roller modules are arranged in parallel with the central shaft and are uniformly arranged between the two upper joint bottom plates, and each variable stiffness pressure spring roller module comprises a pressure spring roller fixing piece and a linear bearing fixing piece, wherein each pressure spring roller fixing piece comprises two cylinders, and the involute leaf springs penetrate through gaps between the two cylinders and are used for clamping the involute leaf springs; the linear bearing fixing piece is provided with a central hole, and the axis of the central hole is parallel to the arrangement direction of the two columns; the linear bearing driving module comprises a variable-rigidity external gear, a variable-rigidity mechanism bearing and a plurality of guide rods, wherein the variable-rigidity external gear is connected with the variable-rigidity mechanism bearing through a plurality of straight rods, and the variable-rigidity mechanism bearing is sleeved on the central shaft; one end of the guide rod is fixed to the variable-rigidity external gear, and the other end of the guide rod is fixed to the variable-rigidity mechanism bearing; the guide rod is provided with a linear bearing, and the linear bearing sleeve is fixed in a central hole of the linear bearing fixing piece; the central shaft rotary output module comprises two lower joint bottom plates and a lower joint connecting plate, the two lower joint bottom plates are respectively arranged on the inner surface of the upper joint bottom plate, a plurality of through involute channels are arranged on the surface of the lower joint bottom plate, and two ends of the variable stiffness pressure spring roller module are respectively arranged in the involute channels; a pinion and a second motor are arranged on the lower joint bottom plate, the pinion is meshed with the rigidity-variable external gear, and the second motor is used for driving the pinion; the lower joint connection plate is U-shaped, and two sides of the U-shape are respectively connected with the lower joint bottom plate.

Preferably, the variable stiffness pressure spring roller module further comprises two miniature flange bearings, the two miniature flange bearings are respectively connected with one ends of the pressure spring roller fixing piece and the linear bearing fixing piece through a straight rod, and the two miniature flange bearings are arranged in the involute channel so as to slide in the involute channel.

Preferably, a guide rod fixing seat is arranged outside the rigidity-changing mechanism bearing, one end of the guide rod is fixed on the rigidity-changing external gear, and the other end of the guide rod is fixed on the guide rod fixing seat.

Preferably, the number of the guide rod, the involute leaf spring and the variable-rigidity pressure spring roller modules is 4.

Preferably, the arrangement of 4 guide rods in the linear bearing drive module is perpendicular to each other.

Preferably, the free end of each involute leaf spring is provided with a leaf spring end fixing piece.

Preferably, the variable-rigidity pressure spring roller module further comprises an aluminum sleeve, concave holes are formed in the connecting surfaces of the pressure spring roller fixing piece and the linear bearing fixing piece, and the aluminum sleeve is arranged in the concave holes to axially position the pressure spring roller fixing piece and the linear bearing fixing piece.

Preferably, the motor driving assembly comprises a rotating motor, a small belt pulley, a large belt pulley and a synchronous belt, wherein the rotating motor is used for rotating the small belt pulley, the large belt pulley is fixed on the central shaft, and the small belt pulley and the large belt pulley are connected through the synchronous belt.

Preferably, the rotation direction of the plurality of involute channels coincides with the rotation direction of the plurality of involute leaf springs.

Preferably, the compression spring roller fixing piece comprises a compression spring roller lower fixing piece and a compression spring roller upper fixing piece, wherein two cylindrical bosses are arranged on one surface of the compression spring roller lower fixing piece, two cylindrical sleeves are arranged on one surface of the compression spring roller upper fixing piece, and the cylindrical bosses are matched with the cylindrical sleeves; the linear bearing fixing piece comprises a linear bearing lower fixing piece and a linear bearing upper fixing piece, and the linear bearing lower fixing piece is connected with the linear bearing upper fixing piece through bolts.

In general, compared with the prior art, the active variable stiffness rotary joint based on the involute leaf spring has the following beneficial effects:

1. the active rigidity-variable rotary joint based on the involute leaf spring can realize the function of real-time adjustment of the joint rigidity through the rigidity-variable motor with small volume and small weight and the gear meshing transmission, and the involute leaf spring of the core part has the innovation, and meanwhile, the integral elastic element can play excellent effects of buffering, energy storage, softness and the like.

2. When the joint is impacted, the elastic property of the involute leaf spring can enable the joint to bear certain impact, and the involute leaf spring has the effects of buffering and saving energy.

3. Under different action scenes, the involute leaf springs with different thicknesses and materials are replaced, so that the rigidity change output characteristics of the integral joint are inconsistent, and the integral joint is suitable for different action environments.

4. Compared with antagonism control variable stiffness joints, the control method is simpler, the two motors have no coupling, and the control is more free and flexible.

Drawings

FIG. 1 is an oblique view of an active variable stiffness rotary joint based on involute leaf springs of the present application;

FIG. 2 is a side view of an active variable stiffness rotary joint based on involute leaf springs of the present application;

FIG. 3 is an oblique view of the motor drive module of the present application;

FIG. 4 is a front view of the motor drive module of the present application;

FIG. 5 is an oblique view of the involute leaf spring module of the present application;

FIG. 6 is an oblique view of the variable stiffness compression spring roller module of the present application;

FIG. 7 is an exploded view of the variable stiffness compression spring roller module of the present application;

FIG. 8 is an oblique view of a linear bearing drive module of the present application;

FIG. 9 is an exploded view of the linear bearing drive module of the present application;

FIG. 10 is a schematic diagram of the installation of a central shaft rotary output module of the present application;

fig. 11 is a schematic diagram of the installation of the involute leaf spring module, the plurality of variable stiffness pressure spring roller modules, the linear bearing drive module and a portion of the central shaft rotary output module of the present application.

The same reference numbers are used throughout the drawings to reference like elements or structures, wherein:

100-motor drive module:

101-a central axis; 102-upper joint bottom plate; 103-a rotating electric machine; 104-a small belt wheel; 105-large belt wheel; 106, a synchronous belt; 107-upper articulating plates;

200-involute leaf spring module:

201-leaf spring mount; 202-involute leaf springs; 203-leaf spring end mount;

300-variable stiffness pressure spring roller module:

301-a lower fixing piece of the linear bearing; 302-a fixed connection on a linear bearing; 303-aluminum sleeve; 304-a compression spring roller lower fixing piece; 305-a fixing piece on the pressure spring roller; 306-miniature flange bearings;

400-linear bearing drive module:

401-variable stiffness external gear; 402-an external gear fixing ring; 403-linear bearings; 404-a guide rod; 405-a guide rod fixing seat; 406-a variable stiffness mechanism bearing;

500-central axis rotation output module:

501-lower joint bottom plate; 502-a second motor; 503-pinion; 504-lower articulating plates.

Detailed Description

The present application will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present application more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application. In addition, the technical features of the embodiments of the present application described below may be combined with each other as long as they do not collide with each other.

Referring to fig. 1 and 2, the present application provides an active stiffness-variable rotary joint based on an involute leaf spring, which is characterized in that the joint includes a motor driving module 100, an involute leaf spring module 200, a plurality of stiffness-variable pressure spring roller modules 300, a linear bearing driving module 400 and a central shaft rotary output module 500, and the specific structure is as follows.

As shown in fig. 3 and 4, the motor driving module 100 includes a central shaft 101, an upper joint bottom plate 102, and an upper joint connecting plate 107, wherein two ends of the central shaft 101 are respectively connected with an upper joint bottom plate 102 through bearings, a motor driving assembly is disposed on one upper joint bottom plate 102 for driving the central shaft 101 to rotate, the upper joint connecting plate 107 is in a U shape, and two sides of the U shape are respectively connected with the upper joint bottom plate 102. The motor drive module 100 is based on exhibiting a symmetrical distribution as a whole. The upper joint substrate 102 is preferably disc-shaped. Specifically, the central shaft 101 is connected to the upper joint bearing seat 108 through an upper joint bearing 109, so as to reduce friction. The upper joint coupling plate 107 is used to connect one end joint of the rotary joint.

In a further preferred embodiment, the motor drive assembly comprises a rotating motor 103, a small pulley 104, a large pulley 105 and a synchronous belt 106, wherein the rotating motor 103 is used for rotating the small pulley 104, the large pulley 105 is fixed on the central shaft 101, and the small pulley 104 and the large pulley 105 are connected through the synchronous belt 106.

As shown in fig. 5, the involute leaf spring module 200 includes a leaf spring fixing member 201 and a plurality of involute leaf springs 202, wherein one ends of the involute leaf springs 202 are uniformly fixed on the leaf spring fixing member 201, and the leaf spring fixing member 201 is sleeved and fixed on the central shaft 101. The leaf spring fixing member 201 may be composed of a plurality of arc-shaped units, and an involute leaf spring 202 is clamped and fixed between each two arc-shaped units. In the embodiment of the application, the number of the involute leaf springs 202 is 4, and 4 circular arc units are correspondingly arranged. Leaf spring mount 201 may be secured to central shaft 101 by bolts. The sketch shape of the involute leaf springs 202 fully considers the problems of the variation range of the joint rigidity and the overall size, and when the relative positions of the variable rigidity pressure spring roller modules 300 on two sides of each involute leaf spring 202 are kept unchanged, the overall four involute leaf springs 202 are equivalent to serial elastic drivers SEA with constant rigidity values, and the characteristic of passive flexibility in the process of rotating joint movement can be realized. And when the variable stiffness pressure spring roller modules 300 on two sides of the involute leaf spring 202 perform tangential motion along the involute curve, the stiffness value is changed, so that the whole rotary joint realizes the active variable stiffness function.

The free end of each involute leaf spring 202 is provided with a leaf spring end anchor 203. Leaf spring end mount 203 may constrain the maximum range of motion of variable stiffness compression spring roller module 300.

The variable stiffness pressure spring roller modules 300 are arranged in parallel with the central shaft 101 and are uniformly arranged between the two upper joint bottom plates 102, the variable stiffness pressure spring roller modules 300 comprise pressure spring roller fixing pieces and linear bearing fixing pieces, wherein the pressure spring roller fixing pieces comprise two cylinders, and the involute leaf springs 202 penetrate through gaps between the two cylinders and are used for clamping the involute leaf springs 202; the linear bearing fixing piece is provided with a central hole, and the axis of the central hole is parallel to the arrangement direction of the two columns.

As shown in fig. 6 and 7, the variable stiffness pressure spring roller module 300 further includes an aluminum sleeve 303, the connection surfaces of the pressure spring roller fixing member and the linear bearing fixing member are provided with concave holes, and the aluminum sleeve 303 is disposed in the concave holes to realize axial positioning of the pressure spring roller fixing member and the linear bearing fixing member.

The compression spring roller fixing piece comprises a compression spring roller lower fixing piece 304 and a compression spring roller upper fixing piece 305, two cylindrical bosses are arranged on one surface of the compression spring roller lower fixing piece 304, two cylindrical sleeves are arranged on one surface of the compression spring roller upper fixing piece 305, and the cylindrical bosses are matched with the cylindrical sleeves; the linear bearing fixing piece comprises a linear bearing lower fixing piece 301 and a linear bearing upper fixing piece 302, and the linear bearing lower fixing piece 301 and the linear bearing upper fixing piece 302 are connected through bolts. The roller outer side of the fastening piece 305 on the pressure spring roller can clamp the involute leaf spring 202, so that the variable stiffness pressure spring roller module 300 is always tangent with the involute curve when acting on the involute leaf spring 202, and the aim of variable stiffness can be achieved with little force transmission.

As shown in fig. 8 and 9, the linear bearing driving module 400 includes a variable stiffness external gear 401, a variable stiffness mechanism bearing 406, and a plurality of guide rods 404, where the variable stiffness external gear 401 is connected to the variable stiffness mechanism bearing 406 through a plurality of straight rods, and the variable stiffness mechanism bearing 406 is sleeved on the central shaft 101; one end of the guide rod 404 is fixed on the variable stiffness external gear 401, and the other end is fixed on the variable stiffness mechanism bearing 406; the guide rod 404 is provided with a linear bearing 403, and the linear bearing 403 is sleeved and fixed in the central hole of the linear bearing fixing piece, so that the linear bearing 403 can move on the guide rod 404. The variable rigidity external gear 401 may be fixed to the external gear fixing ring 402.

In a further preferred embodiment, a guide rod fixing seat 405 is disposed outside the variable stiffness mechanism bearing 406, one end of the guide rod 404 is fixed to the variable stiffness external gear 401, and the other end is fixed to the guide rod fixing seat 405.

In this embodiment, the number of the guide rods 404, the involute leaf springs 202, and the variable stiffness compression spring roller modules 300 is 4. The 4 guide rods 404 are arranged perpendicular to each other in the linear bearing drive module 400.

As shown in fig. 10 and 11, the central shaft rotary output module 500 includes two lower joint bottom plates 501 and a lower joint connecting plate 504, the two lower joint bottom plates 501 are respectively disposed on the inner surface of the upper joint bottom plate 102, the surface of the lower joint bottom plate 501 is provided with a plurality of through involute channels, and two ends of the variable stiffness pressure spring roller module 300 are respectively disposed in the involute channels; a pinion 503 and a second motor 502 are arranged on the lower joint bottom plate 501, the pinion 503 is meshed with the rigidity-variable external gear 401, and the second motor 502 is used for driving the pinion 503; the lower joint connection plate 504 is U-shaped, and two sides of the U-shape are respectively connected to the lower joint bottom plate 501.

In a further preferred embodiment, the variable stiffness compression spring roller module 300 further includes two micro flange bearings 306, wherein the two micro flange bearings 306 are respectively connected to one ends of the compression spring roller fixing member and the linear bearing fixing member through a straight rod, and the two micro flange bearings 306 are disposed in the involute slot so as to slide in the involute slot.

In a further preferred embodiment, the direction of rotation of the plurality of involute tracks coincides with the direction of rotation of the plurality of involute leaf springs 202.

Because of the nature of involute leaf spring 202, variable stiffness pressure spring roller module 300 requires only a small input force to change the position of the point of action, so that low power, small size second motor 502 can increase force output through a gear ratio, and can reduce a large volume compared to conventional antagonistic variable stiffness dual motor control.

When the wrist rigidity change range needs to be modified according to the working environment, the materials and the thickness of the involute leaf spring only need to be changed by combining the related electromyographic signals and the rigidity relation.

When the motion of the joint needs to be precisely controlled, corresponding sensors such as force, position, angle, acceleration and the like can be added.

It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the application and is not intended to limit the application, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the application are intended to be included within the scope of the application.

Claims

1. An active variable stiffness rotary joint based on involute leaf springs, which is characterized by comprising a motor driving module (100), an involute leaf spring module (200), a plurality of variable stiffness pressure spring roller modules (300), a linear bearing driving module (400) and a central shaft rotary output module (500), wherein:

the motor driving module (100) comprises a central shaft (101), an upper joint bottom plate (102) and upper joint connecting plates (107), wherein two ends of the central shaft (101) are respectively connected with the upper joint bottom plate (102) through bearings, a motor driving assembly is arranged on one upper joint bottom plate (102) and used for driving the central shaft (101) to rotate, the upper joint connecting plates (107) are U-shaped, and two sides of each U-shaped upper joint bottom plate (102) are respectively connected with the upper joint bottom plate;

the involute leaf spring module (200) comprises a leaf spring fixing piece (201) and a plurality of involute leaf springs (202), one ends of the involute leaf springs (202) are uniformly fixed on the leaf spring fixing piece (201), and the leaf spring fixing piece (201) is sleeved and fixed on the central shaft (101);

the variable-rigidity pressure spring roller modules (300) are arranged in parallel with the central shaft (101) and are uniformly arranged between the two upper joint bottom plates (102), the variable-rigidity pressure spring roller modules (300) comprise pressure spring roller fixing pieces and linear bearing fixing pieces, the pressure spring roller fixing pieces comprise two cylinders, and the involute leaf springs (202) penetrate through gaps between the two cylinders and are used for clamping the involute leaf springs (202); the linear bearing fixing piece is provided with a central hole, and the axis of the central hole is parallel to the arrangement direction of the two columns;

the linear bearing driving module (400) comprises a variable-rigidity external gear (401), a variable-rigidity mechanism bearing (406) and a plurality of guide rods (404), wherein the variable-rigidity external gear (401) is connected with the variable-rigidity mechanism bearing (406) through a plurality of straight rods, and the variable-rigidity mechanism bearing (406) is sleeved on the central shaft (101); one end of the guide rod (404) is fixed on the variable-rigidity external gear (401), and the other end of the guide rod is fixed on the variable-rigidity mechanism bearing (406); the guide rod (404) is provided with a linear bearing (403), and the linear bearing (403) is sleeved and fixed in a central hole of the linear bearing fixing piece;

the central shaft rotary output module (500) comprises two lower joint bottom plates (501) and a lower joint connecting plate (504), the two lower joint bottom plates (501) are respectively arranged on the inner surface of the upper joint bottom plate (102), a plurality of through involute channels are arranged on the surface of the lower joint bottom plate (501), and two ends of the variable stiffness pressure spring roller module (300) are respectively arranged in the involute channels; a pinion (503) and a second motor (502) are arranged on the lower joint bottom plate (501), the pinion (503) is meshed with the rigidity-variable external gear (401), and the second motor (502) is used for driving the pinion (503); the lower joint connecting plate (504) is U-shaped, and two sides of the U-shape are respectively connected with the lower joint bottom plate (501).

2. The joint of claim 1, wherein the variable stiffness compression spring roller module (300) further comprises two miniature flange bearings (306), the miniature flange bearings (306) are respectively connected with one ends of the compression spring roller fixing piece and the linear bearing fixing piece through a straight rod, and the miniature flange bearings (306) are arranged in the involute grooves so as to slide in the involute grooves.

3. The joint according to claim 1, characterized in that a guide rod fixing seat (405) is arranged outside the rigidity-changing mechanism bearing (406), one end of the guide rod (404) is fixed to the rigidity-changing external gear (401), and the other end is fixed to the guide rod fixing seat (405).

4. A joint according to claim 1 or 3, characterized in that the number of guide rods (404), involute leaf springs (202) and variable stiffness compression spring roller modules (300) is 4.

5. The joint according to claim 4, wherein the number of guide rods (404) is 4, and two adjacent guide rods (404) are arranged perpendicular to each other in the linear bearing drive module (400).

6. A joint according to claim 1, characterized in that the free end of each involute leaf spring (202) is provided with a leaf spring end mount (203).

7. The joint according to claim 1, wherein the variable stiffness compression spring roller module (300) further comprises an aluminum sleeve (303), the connection surfaces of the compression spring roller fixing piece and the linear bearing fixing piece are provided with concave holes, and the aluminum sleeve (303) is arranged in the concave holes so as to realize axial positioning of the compression spring roller fixing piece and the linear bearing fixing piece.

8. The joint according to claim 1, characterized in that the motor drive assembly comprises a rotating motor (103), a small pulley (104), a large pulley (105) and a timing belt (106), wherein the rotating motor (103) is used for the rotation of the small pulley (104), the large pulley (105) is fixed to the central shaft (101), and the small pulley (104) and the large pulley (105) are connected by the timing belt (106).

9. The joint of claim 1, wherein the direction of rotation of the plurality of involute tracks coincides with the direction of rotation of the plurality of involute leaf springs (202).

10. The joint according to claim 1, wherein the compression spring roller fixing member comprises a compression spring roller lower fixing member (304) and a compression spring roller upper fixing member (305), wherein two cylindrical bosses are arranged on one surface of the compression spring roller lower fixing member (304), two cylindrical sleeves are arranged on one surface of the compression spring roller upper fixing member (305), and the cylindrical bosses are matched with the cylindrical sleeves; the linear bearing fixing piece comprises a linear bearing lower fixing piece (301) and a linear bearing upper fixing piece (302), and the linear bearing lower fixing piece (301) and the linear bearing upper fixing piece (302) are connected through bolts.