Variable stiffness mechanism based on connecting rod mechanism

Abstract

The invention discloses a variable stiffness mechanism based on a connecting rod mechanism. Comprising an input shaft, an output shaft, an input rotating disc in transmission connection with the input shaft, an output rotating disc in transmission connection with the output shaft, a variable-rigidity transmission mechanism used for transmitting power of the input rotating disc to the output rotating disc, and a rigidity adjusting mechanism used for adjusting the transmission rigidity of the variable-rigidity transmission mechanism. The variable-stiffness transmission mechanism comprises a plane multi-connecting-rod mechanism and an elastic piece, the plane multi-connecting-rod mechanism is connected between the input rotating disc and the output rotating disc, and the elastic piece is connected between the plane multi-connecting-rod mechanism and the output rotating disc; the rigidity adjusting mechanism is used for driving the input rotating disc to move in the axial direction to enable the plane multi-connecting-rod mechanism to deform so as to change the driving force arm of the elastic piece to the output rotating disc, and therefore the transmission rigidity of the variable-rigidity transmission mechanism can be adjusted. The variable stiffness mechanism solves the problems of small rotation angle, large rotational inertia, low linearity and the like of the existing variable stiffness mechanism scheme, and has the advantages of turnover, high controllability and the like.

Description

Technical Field

[0001] The present invention belongs to the field of robot drive mechanisms, and particularly relates to a variable stiffness mechanism based on a linkage mechanism. Background Art

[0002] With the rapid development of artificial intelligence and industrial automation, the country has increasingly attached importance to the development of the robot industry. The drive is an important component of the robot, and high-performance drives are conducive to the robot achieving more powerful working capabilities. However, traditional rigid drives have poor adaptability to the environment and insufficient impact resistance, which is not conducive to the robot working under complex working conditions and is prone to damage to the mechanical structure when facing impacts. Adopting variable stiffness drive technology is an important way to improve the performance of robots. At present, most variable stiffness mechanisms do not have the ability to rotate, have a small motion range and a large moment of inertia, which is not conducive to control.

[0003] Therefore, to meet the requirements of large motion range and small moment of inertia of modern industrial robots, the present invention proposes a variable stiffness mechanism using a linkage mechanism. This mechanism can be applied to a robot variable stiffness drive and has the characteristics of a large rotation range and high controllability. Summary of the Invention

[0004] In view of this, the object of the present invention is: to solve the problems of the existing robotic arm drive joint solutions, such as small rotation range, large moment of inertia, and difficulty in meeting the precise variable stiffness control requirements of the robotic arm, and to propose a new solution to achieve a high-performance variable stiffness mechanism with a large rotation range and high controllability.

[0005] To achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0006] A variable stiffness mechanism based on a linkage mechanism, comprising: an input shaft, an output shaft, an input turntable drivingly connected to the input shaft, an output turntable drivingly connected to the output shaft, a variable stiffness transmission mechanism for transmitting the power of the input turntable to the output turntable, and a stiffness adjustment mechanism for adjusting the transmission stiffness of the variable stiffness transmission mechanism; the variable stiffness transmission mechanism includes a planar multi-link mechanism and an elastic member, the planar multi-link mechanism is connected between the input turntable and the output turntable, and the elastic member is connected between the planar multi-link mechanism and the output turntable; the stiffness adjustment mechanism at least includes a reciprocating linear driving device, and the reciprocating linear driving device is used to drive the input turntable to move axially to deform the planar multi-link mechanism, thereby changing the size of the driving arm of the elastic member on the output turntable, so as to adjust the transmission stiffness of the variable stiffness transmission mechanism;

[0007] Further, the planar multi-link mechanism comprises a first connecting rod, a second connecting rod and a connecting member; the input rotary plate, the first connecting rod, the second connecting rod and the connecting member together constitute an inverted crank slider mechanism, and respectively serve as a slider, a connecting rod, a crank and a frame rod of the inverted crank slider mechanism; the connecting member is rotatably matched with the output rotary plate through a bearing I, and the two ends of the elastic member are respectively connected to the first connecting rod and the output rotary plate;

[0008] Further, the reciprocating linear drive device is a screw-nut mechanism, the screw of the screw-nut mechanism is parallel to the input shaft, and the nut is connected to the input rotary disc;

[0009] Furthermore, a plurality of variable stiffness transmission mechanisms are evenly arranged along the circumferential direction of the input turntable and the output turntable;

[0010] Furthermore, a plurality of movable screws for connecting with one end of the elastic member are evenly installed on the outer circle of the output turntable along the circumferential direction;

[0011] Further, the elastic member is a spring;

[0012] Furthermore, the input rotary disc and the input shaft are matched by splines;

[0013] Furthermore, the nut of the screw nut mechanism is connected to the input turntable through a propulsion frame; the base of the propulsion frame is fixedly connected to the nut, and the head of the propulsion frame is provided with a bearing seat, in which a bearing II is installed and matched with the outer circle of the input turntable through the bearing II;

[0014] Furthermore, the propulsion frame is guided to reciprocate by a slide rail parallel to the input shaft, and a slide groove cooperating with the slide rail is provided at the bottom of the propulsion frame base.

[0015] The beneficial effects of the present invention are:

[0016] 1. The variable stiffness mechanism of the present invention cleverly combines the planar four-bar mechanism and the inverted crank slider mechanism, which greatly reduces the rotational inertia of the entire driver, expands the motion range of the driver, and improves the controllability of the driver.

[0017] 2. The variable stiffness mechanism of the present invention can adjust the stiffness of the entire driver in real time through the screw transmission mechanism, thereby achieving real-time adjustment of the stiffness and facilitating real-time optimization control of the entire driver.

[0018] 3. The variable stiffness mechanism of the present invention uses the principle of adjusting the driving force arm to adjust the stiffness. The stiffness variation range is large and the stiffness adjustment process is smooth and stable.

[0019] 4. The variable stiffness mechanism of the present invention separates the stiffness adjustment mechanism from the variable stiffness transmission mechanism, has continuous turnover capability, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0021] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0022] Figure 2 It is a schematic diagram of the propulsion frame structure of the present invention.

[0023] Figure 3 It is a schematic diagram of the input turntable structure of the present invention.

[0024] Figure 4 It is a schematic diagram of the output turntable structure of the present invention.

[0025] Figure 5 It is a schematic diagram of the connecting member structure of the present invention.

[0026] Reference numerals: 1 - outer shell, 2 - connecting member, 3 - rear end cover, 4 - adjusting coupling, 5 - input coupling, 6 - input shaft, 7 - propulsion frame, 8 - input turntable, 9 - spline, 10 - first connecting rod, 11 - second connecting rod, 12 - spring, 13 - output turntable, 14 - output shaft, 15 - flange coupling, 16 - knuckle screw, 17 - front end cover, 18 - slide rail, 19 - lead screw, 20 - nut. Specific embodiments

[0027] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be further described below in conjunction with embodiments.

[0028] Embodiment 1

[0029] As Figure 1 shown, the variable stiffness mechanism based on the connecting rod mechanism of this embodiment includes: an outer shell 1, an input shaft 6, an output shaft 14, an input turntable 8 drivingly connected to the input shaft 6, an output turntable 13 drivingly connected to the output shaft 14, a variable stiffness transmission mechanism for transmitting the power of the input turntable 8 to the output turntable 13, and a stiffness adjustment mechanism for adjusting the transmission stiffness of the variable stiffness transmission mechanism.

[0030] In this embodiment, the outer shell 1 adopts a cylindrical structure, and its two ends are respectively closed by a front end cover 17 and a rear end cover 3. A through hole is provided at the central axis of the front end cover 17 for the output shaft 14 to pass through, and through holes are provided at the central axis and the lower position of the rear end cover 3 for the input shaft 6 and the lead screw 19 to pass through respectively.

[0031] In this embodiment, the variable stiffness transmission mechanism includes four planar multi-link mechanisms and elastic members disposed between the input turntable 8 and the output turntable 13; the planar multi-link mechanism includes a first link 10, a second link 11 and a connecting member 2; the input turntable 8, the first link 10, the second link 11 and the connecting member 2 together form an inverted crank-slider mechanism, and respectively serve as the slider, link, crank and frame bar of the inverted crank-slider mechanism; as Figure 5 shown, the connecting member 2 is of a circular ring structure, and 4 connecting lugs for hinging with the end of the second link 11 are uniformly arranged on the outer circumference of the connecting member 2 in the circumferential direction. The connecting ring is rotationally matched with the outer circumference of the output turntable 13 through a bearing I, and the connecting ring and the output turntable 13 are axially relatively fixed. The elastic member adopts a spring 12, and its two ends are respectively connected to the end of the first link 10 and a knuckle screw 16 on the outer circumference of the output turntable 13; as Figure 4 shown, 4 mounting holes for mounting the knuckle screw 16 are uniformly distributed on the output turntable 13 in the circumferential direction. As Figure 3 shown, the input turntable 8 and the input shaft 6 are in spline fit; the input turntable 8 is provided with a spline hole, and the input shaft 6 is provided with a spline shaft that mates with it. Therefore, the input shaft 6 can drive the input turntable 8 to rotate synchronously through the spline 9. At the same time, the input turntable 8 can slide axially relative to the input shaft 6 under the drive of the stiffness adjustment mechanism.

[0032] The stiffness adjustment mechanism at least includes a reciprocating linear drive device. Among them, the reciprocating linear drive device can adopt any device in the prior art that can output reciprocating linear motion, such as a lead screw-nut mechanism, a hydraulic cylinder, a pneumatic cylinder, etc. The reciprocating linear drive device in this embodiment adopts a lead screw-nut mechanism, which is used to drive the input turntable 8 to move axially to deform the planar multi-link mechanism so as to change the size of the driving force arm of the spring 12 on the output turntable 13, so as to adjust the transmission stiffness of the variable stiffness transmission mechanism; the lead screw 19 of the lead screw-nut mechanism is parallel to the input shaft 6, and one end of it passes through the rear end cover 3 and is connected to the adjusting coupling 4; the nut 20 is connected to the input turntable 8 through a propulsion frame 7; as Figure 2 shown, the base of the propulsion frame 7 is fixedly connected to the nut 20. The head of the propulsion frame 7 is provided with a bearing seat, and a bearing II is installed in the bearing seat and is in fit with the outer circumference of the input turntable 8 through this bearing II. The propulsion frame 7 is guided to reciprocate through a slide rail 18 parallel to the input shaft 6, and a chute that mates with the slide rail 18 is provided at the bottom of the base of the propulsion frame 7; therefore, by driving the lead screw 19 to rotate, the nut 20 can drive the input turntable 8 to move axially along with the propulsion frame 7.

[0033] When the variable stiffness mechanism of the present invention performs power transmission, its transmission route is: input coupling 5 ── input shaft 6 ── input turntable 8 ── first connecting rod 10 ── spring 12 ── ball joint screw 16 ── output turntable 13 ── flange coupling 15 ── output shaft 14. Through the above transmission chain, the power is transmitted from the input shaft 6 to the output shaft 14.

[0034] When the variable stiffness mechanism of the present invention adjusts the stiffness, its transmission route is: adjusting coupling 4 ── lead screw 19 ── nut 20 ── push frame 7 ── input turntable 8 ── first connecting rod 10. The torque is input from the adjusting coupling 4 and transmitted to the lead screw. Then, the nut 20 drives the push frame 7 to perform reciprocating motion. The push frame 7 pushes the input turntable 8 to move axially, causing the first connecting rod 10 to swing, and finally changing the force arm of the spring 12, thereby completing the adjustment of the output stiffness.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A variable stiffness mechanism based on a linkage mechanism, characterized in that Including: An input shaft, an output shaft, an input turntable drivingly connected to the input shaft, an output turntable drivingly connected to the output shaft, a variable stiffness transmission mechanism for transmitting the power of the input turntable to the output turntable, and a stiffness adjustment mechanism for adjusting the transmission stiffness of the variable stiffness transmission mechanism; The variable stiffness transmission mechanism includes a planar multi-link mechanism and an elastic member. The planar multi-link mechanism is connected between the input turntable and the output turntable, and the elastic member is connected between the planar multi-link mechanism and the output turntable. The stiffness adjustment mechanism at least includes a reciprocating linear driving device, and the reciprocating linear driving device is used to drive the input turntable to move axially to deform the planar multi-link mechanism, thereby changing the size of the driving force arm of the elastic member on the output turntable, so as to adjust the transmission stiffness of the variable stiffness transmission mechanism.

2. The variable stiffness mechanism based on a linkage mechanism according to claim 1, characterized in that: The planar multi-link mechanism includes a first link, a second link and a connecting member. The input turntable, the first link, the second link and the connecting member together form an inverted crank-slider mechanism, and respectively serve as the slider, the link, the crank and the frame bar of the inverted crank-slider mechanism. The connecting member is rotatably matched with the output turntable through a bearing I, and both ends of the elastic member are respectively connected to the first link and the output turntable.

3. The variable stiffness mechanism based on a linkage mechanism according to claim 1, wherein: The reciprocating linear driving device is a lead screw-nut mechanism, and the lead screw of the lead screw-nut mechanism is parallel to the input shaft, and the nut is connected to the input turntable.

4. The variable stiffness mechanism based on a linkage mechanism according to claim 1, characterized in that: A plurality of the variable stiffness transmission mechanisms are uniformly arranged along the circumferential direction of the input turntable and the output turntable.

5. The variable stiffness mechanism based on a linkage mechanism according to claim 1, characterized in that: A plurality of knuckle screws for connecting one end of the elastic member are uniformly installed along the circumferential direction of the outer circle of the output turntable.

6. The variable stiffness mechanism based on a linkage mechanism according to claim 1, wherein: The elastic member is a spring.

7. The variable stiffness mechanism based on a linkage mechanism according to claim 1, wherein: The input turntable and the input shaft are in spline fit.

8. The variable stiffness mechanism based on a linkage mechanism according to claim 3, characterized in that: The nut of the lead screw-nut mechanism is connected to the input turntable through a propulsion frame. The base of the propulsion frame is fixedly connected to the nut, and the head of the propulsion frame is provided with a bearing seat. A bearing II is installed in the bearing seat and is in fit with the outer circle of the input turntable through the bearing II.

9. The variable stiffness mechanism based on a linkage mechanism according to claim 8, characterized in that: The propulsion frame is guided to reciprocate through a slide rail parallel to the input shaft, and a chute for cooperating with the slide rail is provided at the bottom of the base of the propulsion frame.

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