CN110053076B

CN110053076B - Variable stiffness driver

Info

Publication number: CN110053076B
Application number: CN201910231413.3A
Authority: CN
Inventors: 姜峣; 田向宇; 冯一骁; 李铁民
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2019-03-26
Filing date: 2019-03-26
Publication date: 2020-11-13
Anticipated expiration: 2039-03-26
Also published as: CN110053076A

Abstract

The invention provides a variable stiffness driver. The variable stiffness driver includes: a drive housing; the driving shaft penetrates through the driving shell; the driven shaft is in transmission connection with the driving shaft in the driving shell; a plate spring located within the drive housing and having one end configured as a fixed end; a sliding shaft movably restricting a deformable length between a free end and a fixed end of the plate spring; a cable mechanism that pulls the sliding shaft to translate in response to rotation of the drive shaft. The driving shaft of the variable-rigidity driver drives the sliding shaft to translate through the rope mechanism so as to change the deformable length of the plate spring, and when an external force impacts the driving shell, the plate spring deforms to change the rigidity of the driving shell, so that the driving shell has a flexible buffering effect, the rigid collision is prevented, and the safety in the use process is improved.

Description

Variable stiffness driver

Technical Field

The invention relates to the technical field of flexible driving, in particular to a variable stiffness driver.

Background

The robot has been widely applied to various fields such as manufacturing industry, aerospace, medical treatment, rescue and the like through development of more than half a century, and plays an important role in modern society. In recent years, more and more application scenarios require that the robot cooperates with a human in a more complex environment, and therefore, a cooperative robot appears, and the robot gradually shifts from the requirement of a traditional robot on high rigidity and high dynamic response characteristics to the requirement on safety, adaptability, flexibility and other characteristics.

In order to realize human-computer cooperation, safety is necessarily the most important index, in order to ensure the running precision and speed of the traditional industrial robot, the robot body is designed and manufactured to be as rigid as possible, and a high-rigidity driver is selected to avoid the deformation and vibration of the robot under load, but the danger is caused when the robot works with the human, for example, when the robot collides with the human, the robot cannot realize flexible buffering due to high rigidity, so that the danger is greatly generated to the human.

Disclosure of Invention

In order to solve the above technical problem, the present invention provides a variable stiffness driver, including:

a drive housing;

the driving shaft penetrates through the driving shell;

the driven shaft is in transmission connection with the driving shaft in the driving shell;

a plate spring located within the drive housing and having one end configured as a fixed end;

a sliding shaft movably restricting a deformable length between a free end and a fixed end of the plate spring;

a cable mechanism that pulls the sliding shaft to translate in response to rotation of the drive shaft.

Optionally, the sliding device further comprises a sliding connection plate, wherein the sliding connection plate guides the translation of the sliding shaft.

Optionally, the sliding connection plate includes a sliding groove, and the sliding shaft is inserted into the sliding groove.

Optionally, the cord mechanism comprises a first cord and a second cord;

the first and second ropes are wound around the driving shaft in opposite directions, and the first and second ropes pull the sliding shaft in opposite directions.

Optionally, the two leaf springs are respectively disposed on two sides of the driving shaft, the centers of the first rope and the second rope are wound around the driving shaft in opposite directions, and two ends of the first rope and two ends of the second rope are wound around the two sliding shafts in opposite directions.

Optionally, the method further comprises:

the driving bevel gear is arranged at the output end of the driving shaft;

the driven bevel gear is arranged at the input end of the driven shaft;

wherein the driving bevel gear and the driven bevel gear are engaged.

Optionally, the driven bevel gear is engaged between the two driving bevel gears.

Optionally, the driven shaft and the driving shaft are mounted on a gear seat through a bearing, and the gear seat is fixedly connected with the sliding connection plate.

Optionally, the sliding shaft has clamping portions arranged oppositely, and the plate spring is clamped between the two clamping portions in a sliding manner.

Optionally, the power device is in transmission connection with the input end of the driving shaft.

According to the technical scheme, the driving shaft of the variable-rigidity driver drives the sliding shaft to translate through the rope mechanism so as to change the deformable length of the plate spring, when an external force impacts the driving shell, the plate spring deforms to change the rigidity of the driving shell, so that the driving shell has a flexible buffering effect, rigid collision is prevented, the safety in the using process is improved, and the variable-rigidity driver is compact in structure, high in integration level and small in occupied space.

Drawings

The following drawings are only schematic illustrations and explanations of the present invention, and do not limit the scope of the present invention.

Fig. 1 is a perspective view of a variable stiffness driver according to an embodiment of the present invention.

FIG. 2 is a front view of a variable stiffness driver according to an embodiment of the present invention.

Fig. 3 is a side view of a drive assembly according to an embodiment of the present invention.

Fig. 4 is a sectional view taken along the line a in fig. 3.

Fig. 5 is a perspective view of a drive assembly according to an embodiment of the present invention.

Fig. 6 is a sectional view of a slide shaft according to an embodiment of the present invention.

Wherein: 1 drive assembly

11 drive housing

111 external drive part, 111a connecting hole, 112 cylinder, 113 end cover, 114 shell bearing

12 driving bevel gear shaft,

121 drive bevel gear, 122 drive shaft, 122a input end and 122b rope groove

13 driven bevel gear shaft,

131 driven bevel gear, 132 driven shaft

14 gear seat

141 active bearing, 142 passive bearing, 143 limit cover, 143a contact part

15 a sliding connecting plate,

151 limit cover part, 152 extension part and 153 sliding groove

16 sliding shaft

161 sliding part, 161a rolling groove, 162 clamping part, 162a sliding column part and connecting part 163

17 leaf spring, 18 first rope, 19 second rope

2 power plant

21 support, 22 power element

31 first pulley block

311 a first pulley support, 312 a first pulley, 313 a first rotating shaft

32 second pulley block

321 second pulley support, 322 second pulley, 323 second rotating shaft

Detailed Description

In order to more clearly understand the technical features, objects, and effects of the present invention, embodiments of the present invention will now be described with reference to the accompanying drawings, in which like reference numerals refer to like parts throughout.

"exemplary" means "serving as an example, instance, or illustration" herein, and any illustration, embodiment, or steps described as "exemplary" herein should not be construed as a preferred or advantageous alternative.

For the sake of simplicity, the drawings are only schematic representations of the parts relevant to the invention, and do not represent the actual structure of the product. In addition, in order to make the drawings concise and understandable, components having the same structure or function in some of the drawings are only schematically illustrated or only labeled.

In this document, "upper", "lower", "front", "rear", "left", "right", and the like are used only to indicate relative positional relationships between relevant portions, and do not limit absolute positions of the relevant portions.

In this document, "first", "second", and the like are used only for distinguishing one from another, and do not indicate the degree and order of importance, the premise that each other exists, and the like.

In this context, "equal", "same", etc. are not strictly mathematical and/or geometric limitations, but also include tolerances as would be understood by a person skilled in the art and allowed for manufacturing or use, etc. Unless otherwise indicated, numerical ranges herein include not only the entire range within its two endpoints, but also several sub-ranges subsumed therein.

To solve the technical problems of the prior art, as shown in fig. 1 and 2, an embodiment of the present invention provides a variable stiffness driver including a pair of power devices 2 and a driving assembly 1 between the power devices 2.

The drive assembly 1 has an external drive portion 111, and the power plant 2 is connected to the drive assembly 1 and connected to and provides a driving force of an external device through the external drive portion 111. Alternatively, the power unit 2 may include a bracket 21 and a power member 22, the power member 22 being mounted to the bracket 21, and an output end of the power member 22 being connected to the drive assembly 1. And further optionally the axes of the output shafts of the power units 2 arranged in pairs coincide to save space required for the installation of the drive.

The driving assembly 1 specifically includes a driving housing 11 and a driving bevel gear shaft 12, a driven bevel gear shaft 13, a gear holder 14, a sliding connection plate 15, a sliding shaft 16, a plate spring 17, a first rope 18, and a second rope 19 located inside the driving housing 11.

The driving housing 11 includes a cylinder 112 and an end cover 113, the cylinder 112 and the end cover 113 are installed inside as an installation space, the external driving portion 111 is located in the end cover 113, and the external driving portion 111 protrudes out of the edge of the end cover 113, the external driving portion 111 is connected to an external device, specifically, the external driving portion 111 may be provided with a connection hole 111a, and connected to the external device through the connection hole 111 a.

The drive bevel gear shaft 12 includes a drive bevel gear 121 and a drive shaft 122 which are integrated, the driven bevel gear shaft 13 includes a driven bevel gear 131 and a driven shaft 132 which are integrated, the two drive bevel gears 121 are disposed opposite to each other, the two driven bevel gears 131 are disposed between the two drive bevel gears 121, and each of the driven bevel gears 131 is engaged with the two drive bevel gears 121, optionally, the two drive bevel gear shafts 12 are the same in size, and the two driven bevel gear shafts 13 are the same in size. The input ends 122a of the two driving shafts 122 are arranged outside the end cover 113 of the driving shell 11 in a penetrating way, and the input ends 122a of the driving shafts 122 are in transmission connection with the output end of the power element 22, and optionally, the driving shafts 122 are rotated relative to the end cover 113 through a shell bearing 114.

It can be seen that the engagement of the drive bevel gear 121 and the driven bevel gear 131 effects a driving connection between the drive shaft 122 and the driven shaft 132, which effects an angular change of the drive housing 11 driven by the power unit 2. Of course, it is not excluded that only one driven shaft 132 is provided, but one driven shaft 132 can also be brought into driving connection with the driving shaft 122.

It can be understood that the connection between the driving bevel gear 121 and the driving shaft 122 is not limited to an integral type, but may be a split type arrangement, and only the two are required to be fixedly connected to realize synchronous rotation, and likewise, the driven bevel gear 131 and the driven shaft 132 may also be split type.

In an optional example, the input end 122a of the driving shaft 122 is provided with a groove, the output end of the corresponding power device 2 is provided with a protrusion matched with the groove, the input end 122a of the driving shaft 122 and the output end of the power device 2 are both sleeved in the sleeve, the groove is matched with the protrusion, and the driving shaft 122 is connected with the power device 2.

The driving bevel gear shaft 12 and the driven bevel gear shaft 13 are both mounted on the gear base 14, the gear base 14 is rectangular, the driving bevel gear 121 and the driven bevel gear 131 are both located on the inner wall of the gear base 14, a shaft hole is formed in the side wall of the gear base 14, the driving shaft 122 is mounted on the shaft hole of the gear base 14 through the driving bearing 141, the driven shaft 132 is mounted on the shaft hole of the gear base 14 through the driven bearing 142, and the driving shaft 122 and the driven shaft 132 can rotate relative to the gear base 14.

In an alternative example, a limiting cover 143 is disposed on an outer side of the driven shaft 132 of the gear seat 14, the limiting cover 143 is used for limiting a driven bearing in the shaft hole, specifically, an abutting portion 143a is disposed on an inner side of the limiting cover 143, the abutting portion 143a abuts against the driven bearing 142, and the driven bearing is prevented from coming out of the shaft hole, and further alternatively, the limiting cover 143 may be fixed to the gear seat 14 by a screw.

The outer side of the gear seat 14 where the driving shaft 122 is mounted is fixedly provided with mutually parallel and opposite sliding connection plates 15, each sliding connection plate 15 comprises an integrated limiting cover portion 151 and an extending portion 152, each limiting cover portion 151 is used for limiting a driving bearing 141 in a shaft hole, and specifically, the limiting cover portions 151 abut against the driving bearings 141; the restraining cap 151 is formed with a through hole allowing the driving shaft 122 to protrude. The extending portions 152 extend towards two sides far away from the driving shaft 122 respectively, the extending portions 152 are provided with sliding grooves 153 in the extending direction, the sliding shafts 16 are slidably installed between the sliding grooves 153 which are oppositely arranged, that is, the sliding connecting plates 15 are provided with the sliding grooves 153 at two sides of the driving shaft 122 respectively, the sliding grooves 153 of the two sliding connecting plates 15 are oppositely arranged, the two sliding shafts 16 are located at two sides of the driving shaft 122 respectively, two ends of each sliding shaft 16 are located in the corresponding sliding grooves 153 respectively, and the sliding shafts 16 can translate along the sliding grooves 153.

The slide shaft 16 includes a slide portion 161, a clamping portion 162, and a connecting portion 163, the two clamping portions 162 are connected to the end of the connecting portion 163, the two clamping portions 162 are clamping members, the slide portion 161 is connected to the connecting portion 163, and the slide portion 161 extends in a direction away from the connecting portion 163. The plate spring 17 is clamped between each clamping portion 162, the plate spring 17 is clamped by the clamping portion 162 of the sliding shaft 16 in a sliding mode, one end of the plate spring 17 is a fixed end, the other end of the plate spring 17 is a free end, the fixed end is fixed on the inner wall surface of the cylinder 112 of the driving shell 11, the plate spring 17 is a cantilever type plate spring, along with the change of the clamping portion 162 of the sliding shaft 16 in the clamping position of the plate spring 17, the corresponding effective deformable length of the plate spring 17 is changed, the elastic length of the plate spring 17 is released, when the driving shell 11 is subjected to external force, the plate spring 17 generates deformation, the elastic force of the deformation buffers the driving shell 11, and the two plate springs 17 are respectively located on two sides of the driving bevel gear shaft 12, the driving bevel gear shaft is preferably symmetrically arranged. Alternatively, the clamping position of the clamping portion 162 is the spool portion 162a with the diameter increased, and since the diameter of the spool portion 162a is increased, the spool portion 162a can be sufficiently contacted with the plate spring 17 even during the relative sliding of the spool portion 162a and the plate spring 17, ensuring that the effective length of the plate spring 17 is continuously changed.

The leaf springs 17 act as elastic elements to achieve elastic damping of the drive housing 11 when subjected to an external force, and although the leaf springs 17 are arranged in pairs in this example, it is not excluded that only one leaf spring 17 is provided, and one leaf spring 17 can also achieve elastic damping of the drive housing 11. The sliding clamping of the plate spring 17 by the sliding shaft 16 aims at changing the deformable length of the plate spring 17, the sliding shaft 16 forms a constraint for the plate spring 17, the clamping position of the sliding shaft 16 for the plate spring 17 forms the other fixed end of the plate spring 17, so that the sliding shaft 16 constrains the effective length of the plate spring between the two fixed ends, and the length between the two fixed ends is the deformable length of the plate spring 17.

The sliding part 161 of the sliding shaft 16 is circumferentially provided with parallel rolling grooves 161a, the driving shaft 122 is circumferentially provided with parallel rope grooves 122b, the outer wall of the sliding connecting plate 15 is provided with a first pulley block 31 at a position close to the driving shaft 122, the outer wall of the sliding connecting plate 15 is provided with a second pulley block 32 at a position far away from the driving shaft 122, and the first pulley block and the second pulley block 32 are centrosymmetric relative to the driving shaft 122.

The first rope 18 is arranged on the outer side of the sliding connection plate 15, the center of the first rope 18 is wound on the driving shaft 122, one end of the first rope 18 is wound on the first pulley block 31 and then fixed on the rolling groove 161a of the sliding shaft 16 on the same side with the first pulley block 31, and the other end of the first rope 18 is wound on the second pulley block 32 on the other side of the sliding connection plate 15 and then fixed on the sliding groove 161a of the sliding shaft 16 on the same side with the second pulley block 32.

Similarly, a second rope 19 is further disposed on the outer side of the same sliding connection plate 15, the center of the second rope 19 is wound around the driving shaft 122 in the opposite winding direction to the first rope 18, one end of the second rope 19 is wound around another first pulley block 31 and then fixed to the rolling groove 161a of the sliding shaft 16 on the same side as the first pulley block 31, and the other end of the second rope 19 is wound around a second pulley block 32 on the other side of the sliding connection plate 15 and then fixed to the sliding groove 161a of the sliding shaft 16 on the same side as the second pulley block 32.

It can be seen from the above winding manner that the centers of the first rope 18 and the second rope 19 are wound in opposite directions around the rope groove 122b of the driving shaft 122, and the two ends are respectively wound around the first pulley block 31 and the second pulley block 32 at the two ends of the driving shaft of the sliding connection plate 15, when the driving shaft 122 rotates, the first rope 18 and the second rope 19 at the same side respectively shorten and elongate or respectively elongate and shorten, so that the two sliding shafts 16 are simultaneously close to the driving shaft 122 or simultaneously far from the driving shaft 122, and the movement of the sliding shafts 16 is synchronous, it is ensured that the clamping positions of the sliding shafts 16 at the plate springs 17 are the same, and further, the effective lengths of the plate springs 17 are the same, and it is prevented that the driving housing 11 shakes due to different elastic deformations of the two plate springs 17.

The first rope 18 and the second rope 19 form a rope mechanism, the rope mechanism pulls the sliding shaft 16 to translate corresponding to the rotation of the driving shaft 122, specifically, the first rope 18 and the second rope 19 pull the sliding shaft 16 in opposite directions, the lengths of the single sides of the first rope 18 and the second rope 19 are changed to realize the translation of the sliding shaft 16, the effective length of the plate spring 17 is changed when the sliding shaft 16 translates, and the translation of the sliding shaft 16 is guided by the sliding groove 151 of the sliding connecting plate 15 to prevent the sliding shaft 16 from deflecting during the translation. Of course, it is not excluded to omit the first pulley block 31 and the second pulley block 32, and a change in the length of the ropes on both sides of the axle shaft 122 can still be achieved without pulley blocks.

In a specific example, for example, the first rope 18 is wound around the driving shaft 122 clockwise, the second rope 19 is wound around the driving shaft 122 counterclockwise, when the driving shaft 122 rotates clockwise, the length of the first rope 18 on one side of the sliding link plate 15 is elongated, the length of the second rope 19 on the one side is shortened due to the winding direction of the second rope 19 opposite to that of the first rope 18, the side sliding shaft 16 moves away from the driving shaft 122, the length of the first rope 18 on the other side is shortened, the length of the second rope 19 is elongated, the side sliding shaft 16 also moves away from the driving shaft 122, and the moving distances of the sliding shafts 16 on both sides are the same.

In a specific use process, the output end of the power equipment 2 drives the driving bevel gear shaft 12 of the driving assembly to rotate, when the power equipment 2 on two sides drives the two driving bevel gear shafts 12 to rotate in the same direction and at the same speed relative to the driven bevel gear shaft 13, the driven bevel gear 131 cannot rotate, the driven bevel gear 131 rotates around the axis of the driving bevel gear shaft 12, the driving bevel gear 121 is a sun gear, the driven bevel gear 131 is a planet gear, the planet gear rotates around the sun gear, because the driven shaft 132 of the driven bevel gear shaft 13 is installed on the gear seat 14, the gear seat 14 rotates around the driving bevel gear 121 along with the driven bevel gear 131, and the gear seat 14 sequentially drives the sliding connection plate 15, the sliding shaft 16, the plate spring 17 and the driving shell 11 to rotate around the axis of the driving bevel gear shaft 12, at this time, the rotation angle of the driving shell 11 changes, but because, Since the slide shaft 16 and the leaf spring 17 both rotate in the same direction and at the same speed, the first rope 18 and the second rope 19 do not change in length, the position of the slide shaft 16 between the leaf spring 17 does not change, the elasticity of the leaf spring 17 does not change, and the rigidity of the actuator does not change.

When the power devices 2 on both sides drive the two driving bevel gear shafts 12 to rotate reversely at the same speed, the driving bevel gear 121 drives the driven bevel gear 131 to rotate, at this time, the gear seat 14, the sliding connection plate 15, the sliding shaft 16, the plate spring 17 and the driving housing 11 have no angle change, the rotation angle of the driver has no change, but an angle difference is generated between the driving shaft 122 and the sliding connection plate 15, the sliding shaft 16 and the plate spring 17, when the driving shaft 122 rotates, the lengths of the first rope 18 and the second rope 19 on both sides of the driving shaft 122 are driven to change, the sliding shafts 16 on both sides simultaneously approach or simultaneously separate from the driving shaft 122, so as to change the effective elastic length of the plate spring 17, the elastic change of the plate spring 17 itself, the driving housing 11 fixedly connected with the plate spring 17 simultaneously changes in elasticity, so as to change the elasticity of the external driving part 111 relative to external devices, when the driver collides with the outside, the driver has buffering effect, the elastic change of the plate spring 17 prevents the rigid touch from generating large damage.

When the power equipment 2 on two sides drives the two drive bevel gear shafts 12 to rotate in a differential manner, the drive bevel gear 121 drives the driven bevel gear 131 to rotate and rotate around the axis of the drive bevel gear shaft 12, at this time, the gear seat 14, the sliding connection plate 15, the sliding shaft 16, the plate spring 17 and the drive shell 11 all change along with the angle of the driven bevel gear 131, but the rotation of the drive shaft 122, the sliding connection plate 15, the sliding shaft 16, the plate spring 17 and the drive shell 11 has an angle difference, so that the first rope 18 and the second rope 19 simultaneously change the length on two sides of the drive shaft 122, and the effective length of the plate spring 17 changes, thereby simultaneously changing the rotation angle and the rigidity of the driver.

Optionally, the first pulley block 31 comprises a first pulley support 311 and a first pulley 312, the first pulley 312 is mounted to the first pulley support 311 by a first rotation shaft 313, and likewise, the second pulley block 32 comprises a second pulley support 321 and a second pulley 322, the second pulley 322 is mounted to the second pulley support 321 by a second rotation shaft 323. The pulley support is located outside the sliding connection plate 15 and does not occupy excess space and increase the volume of the whole drive.

In conclusion, the driving shaft of the variable-rigidity driver drives the sliding shaft to translate through the rope mechanism so as to change the deformable length of the plate spring, when an external force impacts the driving shell, the plate spring deforms to change the rigidity of the driving shell, so that the driving shell has a flexible buffering effect, rigid collision is prevented, the safety in the use process is improved, and the variable-rigidity driver is compact in structure, high in integration level and small in occupied space.

In addition, the driving assembly transmits kinetic energy outwards, the change of the rotating angle of the driver is realized through the matching of the driving bevel gear and the driven bevel gear, the rope and the plate spring are arranged, the plate spring is connected with the external driving part, the elastic force of the plate spring is adjusted through the sliding shaft, and further the adjustment of the rigidity of the external driving part is realized, so that the rigidity and the rotating angle of the driver can be adjusted at the same time, and the safety is high when the driving assembly is applied to a use environment.

In a specific application scenario, the variable stiffness driver can be applied to a robot, and particularly can be applied to joints of the robot, it can be understood that the joints of the robot are easy to deform or vibrate when bearing if the rigidity is too small, namely the deformation is too large, and danger is easily caused to people when collision occurs if the rigidity is too large, and the variable stiffness driver can set the rigidity within a proper threshold range. When the driving shaft 122 is driven to rotate by the power equipment 2, the rope mechanism pulls the sliding shaft 16 to perform reciprocating translation in the sliding groove 151 of the sliding connecting plate 15, when the sliding shaft 16 is positioned at one end, far away from the driving shaft 122, of the sliding groove 151, the sliding shaft 16 clamps the root of the plate spring 17, the plate spring 17 does not have effective deformable length, when the driving shell 11 is impacted by external force, the plate spring 17 cannot generate elastic deformation, and at the moment, the driving shell 11 collides with the outside to be rigid collision; when the sliding shaft 16 is translated to one end of the sliding groove 151 close to the driving shaft 122, the deformable length of the plate spring 17 is the largest, the rigidity of the driving shell 11 is the smallest, namely the deformable length range of the plate spring 17 is determined by the length of the sliding groove 151, the power device 2 can be controlled to control the rotation of the driving shaft 122 in the specific application process, and further the sliding range of the sliding shaft 16 can be controlled, so that the situation that the rope structure or other parts are damaged due to the fact that the driving shaft 122 rotates when the sliding shaft 16 reaches the end of the sliding groove 151 is avoided.

It should be understood that although the present description has been described in terms of various embodiments, not every embodiment includes only a single embodiment, and such description is for clarity purposes only, and those skilled in the art will recognize that the embodiments described herein can be combined as a whole to form other embodiments as would be understood by those skilled in the art.

The above-listed detailed description is only a specific description of a possible embodiment of the present invention and is not intended to limit the scope of the present invention, and equivalent embodiments or modifications such as combinations, divisions or repetitions of the features without departing from the technical spirit of the present invention are included in the scope of the present invention.

Claims

1. A variable stiffness drive comprising:

a drive housing (11);

a drive shaft (122), wherein the drive shaft (122) is arranged in the drive shell (11) in a penetrating way;

a driven shaft (132), wherein the driven shaft (132) is in transmission connection with the driving shaft (122) in the driving shell (11);

a leaf spring (17), the leaf spring (17) being located within the drive housing (11) and one end of the leaf spring (17) being configured as a fixed end;

a sliding shaft (16), the sliding shaft (16) movably constraining a deformable length between a free end and a fixed end of the plate spring (17);

a cable mechanism that pulls the sliding shaft (16) in translation in response to rotation of the drive shaft (122);

a sliding connection plate (15), the sliding connection plate (15) guiding the translation of the sliding shaft (16);

the driven shaft (132) and the driving shaft (122) are mounted on a gear seat (14) through bearings, and the gear seat (14) is fixedly connected with the sliding connection plate (15).

2. The variable stiffness drive according to claim 1, wherein the sliding connection plate (15) comprises a sliding slot (151), and the sliding shaft (16) is inserted into the sliding slot (151).

3. A variable stiffness drive as claimed in claim 1 wherein the cable mechanism comprises a first cable (18) and a second cable (19);

the first and second ropes (18, 19) are wound around the drive shaft (122) in opposite directions, and the first and second ropes (18, 19) pull the slide shaft (16) in opposite directions.

4. The variable stiffness driver according to claim 3, wherein two leaf springs (17) are respectively provided at both sides of the driving shaft (122), and the first rope (18) and the second rope (19) are wound around the driving shaft (122) at the centers thereof in opposite directions and wound around the two sliding shafts (16) at both ends thereof in opposite directions, respectively.

5. The variable stiffness drive of claim 1 further comprising:

the driving bevel gear (121), the driving bevel gear (121) is arranged at the output end of the driving shaft (122);

a driven bevel gear (131), wherein the driven bevel gear (131) is arranged at the input end of the driven shaft (132);

wherein the driving bevel gear (121) and the driven bevel gear (131) are engaged.

6. The variable stiffness drive of claim 5 wherein the driven bevel gear (131) is meshed between two of the drive bevel gears (121).

7. The variable stiffness drive of claim 1 wherein the sliding shaft (16) has oppositely disposed clamping portions (162), the leaf spring (17) being slidably clamped between the two clamping portions (162).

8. A variable stiffness drive as claimed in claim 1 further comprising a power plant (2), the power plant (2) being drivingly connected to the input (122a) of the drive shaft (122).