CN112894873B - An Active Variable Stiffness Joint Based on Rack and Pinion Pair - Google Patents

Abstract

The invention provides an active variable stiffness joint based on a rack-and-pinion, which comprises a shell, an input control end and a variable stiffness adjusting component, wherein the shell comprises a fixed first shell and a movable second shell, the second shell is rotatably arranged on the first shell, the input control end is used for driving the second shell to rotate around the rotation center of the second shell, the input control end comprises an input rotating shaft and a fixed frame, the fixed frame is arranged on the input rotating shaft and rotates synchronously with the input rotating shaft, and the variable stiffness adjusting component is used for adjusting the stiffness value of the joint according to the actual requirement of the second shell and comprises a plate spring, a sliding seat, a movable sliding block, a central gear and a rack. The invention changes the output rigidity by actively adjusting the relative position of the sliding seat and the plate spring, and has the advantages of compact structure, large rigidity adjusting range and strong stability.

Description

An Active Variable Stiffness Joint Based on Rack and Pinion Pair

technical field

The invention belongs to the technical field of robots, and in particular relates to an active variable stiffness joint based on a rack and pinion pair.

Background technique

With the increasing diversification of people's production and living environments, the situation of human-machine collaboration and multi-machine collaboration is becoming more and more common, and the problem of how to ensure the flexibility between multi-machine and human and reduce the collision safety between humans and humans has become increasingly prominent. As the core structural component of the robot body, the joint drive module is not only a power source for the robot to complete various flexible actions, but also a controllable key structural point to ensure the safety of human-computer interaction. The traditional robot drive joint is generally a nearly pure rigid structure composed of a drive motor and a transmission, without elastic elements, which cannot guarantee the safety of human-machine cooperation and the flexibility of the robotic arm.

Compared with the traditional pure stiffness joint, the variable stiffness joint realizes that with the change of the load, its joint stiffness is not constant, and the variable stiffness joint is divided into passive variable stiffness joint and active variable stiffness joint. The most studied passive variable stiffness joint is the series elastic driver, which is an elastic element connected between the ordinary rigid driver and the external load. When the elastic element is determined, the stiffness characteristics of the series elastic driver are also determined; active variable stiffness A joint means that a joint is driven by two motors, and the joint stiffness and output position can be adjusted independently or separately, which overcomes the disadvantage that the stiffness of passive variable stiffness joints cannot be adjusted. This is also a true "variable stiffness flexible" joint.

At present, there are five main structural forms of active variable stiffness joints: antagonistic type, spring type, friction plate type, variable transmission type and hybrid type. Most of them have the problems of complex structure, large volume, poor stability and difficult linear control of stiffness. Patent CN201610847050.2 discloses a robot flexible joint with continuously adjustable rigidity, which can realize adjustable rigidity by compressing the pre-compression of the floating spring. Although the rigidity can be continuously adjusted, it has a complex structure, large volume and poor environmental adaptability. ; Chinese patent CN201510114055.X discloses a flexible joint with variable stiffness, which adopts a multi-stage gear transmission mechanism, and the structure is relatively complex, the transmission process is complex, the precision is low, the stiffness is not easy to control, and the application is limited.

Based on this, it is necessary to provide a compact active variable stiffness joint with a large stiffness adjustment range.

SUMMARY OF THE INVENTION

In view of the defects of the prior art, the present invention provides an active variable stiffness joint based on a rack and pinion pair, which can change the output stiffness by actively adjusting the relative position of the sliding seat and the leaf spring, and has the advantages of compact structure and large stiffness adjustment range. , the advantages of strong stability.

In order to achieve the above object, the present invention provides an active variable stiffness joint based on a rack and pinion pair, which includes a housing, an input control end and a variable stiffness adjustment assembly, and the housing includes a fixed first housing and a movable second housing The casing, wherein the second casing is rotatably arranged on the first casing, and the input control end is used to drive the second casing to rotate around its center of rotation, which includes an input rotating shaft and a fixed frame, and the fixed frame is mounted on the input rotating shaft and is connected with the input shaft. The input shaft rotates synchronously, and the variable stiffness adjustment component is used to adjust the stiffness value of the joint according to the actual needs of the second shell, which includes:

More than one leaf spring, set on the fixing frame;

The sliding seat is slidably arranged on the leaf spring;

Move the slider to be fixedly connected with the slider;

a central gear, located on the second housing and capable of rotating;

A rack capable of driving the sliding slider, the rack is meshed with the central gear, a guide rod is provided on the second housing, and the rack is slidably arranged on the guide rod;

The movable slider is provided with rectangular teeth inclined relative to the guide rod, and the rack is provided with a connecting groove.

The movable slider is slidably connected to the rack through the cooperation of the rectangular teeth and the connecting groove;

The rotating central gear can drive the rack to slide on the guide rod, and the sliding rack drives the sliding block and the sliding seat to slide along the length direction of the leaf spring to adjust the effective length of the leaf spring to change the joint stiffness.

According to another specific embodiment of the present invention, the sliding seat is a roller sliding seat, which includes a seat body and two rollers, the seat body is fixedly connected with the moving slider, and the two rollers are sleeved on the leaf spring.

According to another specific embodiment of the present invention, the axis of the guide rod and the length direction of the leaf spring are perpendicular to each other.

According to another specific embodiment of the present invention, the second housing has a first groove, the guide rod is supported in the first groove, and the rack can slide in the first groove.

According to another specific embodiment of the present invention, the second housing has a second groove, and the moving slider can slide in the second groove.

According to another specific embodiment of the present invention, the number of leaf springs is two or more, and the two or more leaf springs are arrayed around the input shaft or relatively distributed on the fixed frame.

According to another specific embodiment of the present invention, the distances between the sliding seats located on different leaf springs and the input shaft are the same.

According to another specific embodiment of the present invention, the second housing is rotatably arranged in the first housing through two four-point contact thin-wall bearings.

According to another specific embodiment of the present invention, the variable stiffness adjustment assembly further includes a pressure plate and a rigidity motor, the pressure plate is fixed on the second housing, the rigidity motor is arranged on the pressure plate, and the central gear is connected to the pressure plate through a key. on the output shaft of the rigidity motor.

According to another specific embodiment of the present invention, the input control end further includes a drive plate, the drive plate is fixedly connected to the first housing, the input shaft is a stepped shaft, the drive plate is provided with a mounting slot, and one end of the input shaft passes through the The first bearing in the installation slot is connected with the drive plate, and the other end of the input shaft is connected with the second housing through the second bearing.

Compared with the prior art, the beneficial effects of the present invention are:

The invention creatively uses the rack and pinion transmission mode, through the rotation of the central gear, the rack meshing with the central gear moves laterally along its corresponding guide rod, and the movement of the rack drives the moving slider and its fixed sliding seat to move , and then change the effective length of the leaf spring, which has the characteristics of simple structure, large rigidity adjustment range and stable operation without noise.

In the present invention, the central gear and each rack adopt meshing transmission, and the rack and the moving slider cooperate with rectangular teeth and connecting grooves to realize the movement of the sliding seat, so that each rack can synchronously drive the corresponding moving slider and the sliding seat to move, and the rigidity is changed. The joints are highly reliable and stable.

The present invention will be further described in detail below in conjunction with the accompanying drawings.

Description of drawings

Fig. 1 is the overall structure schematic diagram of the variable stiffness joint of the present invention;

Fig. 2 is the sectional view of the variable stiffness joint of the present invention;

Fig. 3 is the internal structure schematic diagram of the variable stiffness joint of the present invention;

4 is a schematic structural diagram of a central gear and a rack in the variable stiffness joint of the present invention;

5 is a schematic diagram of the cooperation between the moving slider and the second groove in the variable stiffness joint of the present invention;

Fig. 6 is the structural schematic diagram of the inner casing in the variable stiffness joint of the present invention;

7 is a schematic diagram of the distribution of three leaf springs in the variable stiffness joint of the present invention;

8 is a schematic structural diagram of a single rack in the variable stiffness joint of the present invention;

FIG. 9 is a schematic structural diagram of the moving slider in the variable stiffness joint of the present invention.

Detailed ways

In order to understand the above objects, features and advantages of the present invention more clearly, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments may be combined with each other in the case of no conflict.

Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific details disclosed below. Example limitations.

Example 1

This embodiment provides an active variable stiffness joint based on a rack and pinion pair, as shown in FIGS. 1-9 , including a housing 100 , an input control end 200 and a variable stiffness adjustment assembly 300 .

The casing 100 includes a nested first casing 110 and a second casing 120, wherein the first casing 110 is an outer casing, the second casing 120 is an inner casing, and the second casing 120 preferably adopts two four-point The contact thin-wall bearing 130 is rotatably disposed in the first housing 110 .

The input control end 200 is used to drive the second housing 120 to rotate around its center of rotation, and includes a drive plate 210 , a position motor 220 , an input shaft 230 and a fixing frame 240 .

The drive plate 210 is fixedly connected with the first housing 110 , the position motor 220 is assembled on the drive plate 210 , wherein the output shaft of the position motor 220 is a D-shaped shaft, and the input shaft 230 is provided with a D-shaped hole to connect with the output shaft of the position motor 220 One end is fixedly connected, the input shaft 230 is arranged on the rotation center line of the second housing 120 , the fixing frame 240 is arranged on the input shaft 230 and rotates synchronously with the input shaft 230 .

Specifically, the input shaft 230 is a stepped shaft, and the drive plate 210 is provided with an installation slot 211 . One end is connected to the second housing 120 for rotational support through the second bearing 260 .

The variable stiffness adjustment assembly 300 is used to adjust the stiffness value of the joint according to the actual needs of the second housing 120, and includes a pressure plate 310, a stiffness adjustment motor 320, a leaf spring 330, a sliding seat 340, a moving slider 350, a guide rod 360, Sun gear 370 and rack 380.

The number of leaf springs 330 is preferably at least three, for example, the three leaf springs 330 shown in FIG. 3 are distributed on the outer circumference of the input shaft 230 in an array; The seat 340 is fixedly connected, and the other end is connected with the rack 380 in a sliding fit.

The second casing 120 is provided with a central groove 121, a first groove 122 and a second groove 123, the pressure plate 310 is fixed on the second casing 120, the stiffness adjusting motor 320 is arranged on the pressure plate 310, and the central gear The 370 is provided on the output shaft of the rigidity motor 320 through a key connection, and the central gear 370 is located in the central groove 121, and is driven by the rigidity motor 320 to rotate forward or reversely.

As shown in FIG. 4 , the guide rod 360 is supported in the first groove 122 perpendicular to the length direction of the leaf spring 330 , and the rack 380 is sleeved on the guide rod 360 and can slide in the first groove 122 . The rack 380 is always meshed with the central gear 370 during the sliding process, and when the central gear 370 rotates, each rack 380 is driven by the rack and pinion 380 to slide linearly along the guide rod 360;

As shown in FIG. 5 , the moving slider 350 is slidably disposed in the second groove 123 , and the moving slider 350 slides outward or inward under the driving of the rack 380 .

In this embodiment, the matching connection between the rack 380 and the moving slider 350 is as follows: as shown in FIG. A connecting groove 381 is provided, and the moving slider 350 is slidably connected to the rack 380 through the cooperation of the rectangular teeth 351 on the sliding block 351 and the connecting groove 381. When the rack 380 slides, it can drive the moving slider 350 along the second groove. 123 Slide outward or inward.

Further, the distances between the sliders 340 located on different leaf springs 330 and the input shaft 230 are the same, so that the sliding of the movable slider 350 is symmetrical and constant velocity, and the sliding of the sliders 340 is also symmetrical and constant velocity.

The sliding seat 340 in this embodiment is preferably a roller sliding seat, which includes a seat body 341 and two rollers 342. The seat body 341 is fixedly connected with the moving slider 350, and the two rollers 342 are sleeved on the leaf spring 330, two of which are The distance between the rollers 342 is the thickness of the leaf spring 330 .

The location transmission process in this embodiment is:

The position motor 220 drives the input shaft 230 to rotate. The input shaft 230 drives the three leaf springs 330 fixedly connected to it to rotate through the fixing frame 240 , and then drives the sliding seat 340 sleeved on the leaf springs 330 to revolve around the center of rotation of the first housing 110 Rotating, because the sliding seat 340 and the moving slider 350 are fixedly connected, then the sliding seat 340 drives the moving slider 350 to rotate around the center of rotation of the first housing 110 , and the second housing 120 is driven by the moving slider 350 to rotate around The center of rotation rotates, and finally the output rotation is performed through the output link arm 140 provided on the second housing 120 .

The active variable stiffness process of this embodiment is:

The stiffness-adjusting motor 320 drives the central gear 370 to rotate relative to the center of rotation of the second housing 120 , and the central gear 370 drives the three racks 380 through the rack and pinion 380 to slide linearly along the guide rods 360 matched with them, and pass The rack 380 drives the moving slider 350 to slide along the second groove 123, and finally drives the slider 340 to move outward or inward along the length direction of the leaf spring 330, so as to adjust the effective length of the leaf spring 330 and change the joint stiffness. .

Although the present invention is disclosed above with preferred embodiments, it is not intended to limit the scope of implementation of the present invention. Any person of ordinary skill in the art can make some improvements without departing from the scope of the present invention, that is, all equivalent improvements made according to the present invention should be covered by the scope of the present invention.

Claims (8)

1. The utility model provides an initiative variable stiffness joint based on rack and pinion, its includes casing, input control end and variable stiffness adjusting part, the casing is including the second casing of fixed first casing and activity, wherein the second casing rotates to set up on the first casing, the input control end is used for the drive the second casing rotates around its centre of gyration, and it includes input pivot and mount, the mount is established input pivot is last and with input pivot synchronous rotation, variable stiffness adjusting part is used for the basis the rigidity value of joint is adjusted to the actual need of second casing, and it includes:

more than one plate spring, set up on the said fixed mount;

a slider slidably disposed on the plate spring;

the movable sliding block is fixedly connected with the sliding seat;

a sun gear positioned on the second housing and capable of rotating;

the rack can drive the movable sliding block to slide, the rack is meshed with the central gear, a guide rod is arranged on the second shell, the rack is arranged on the guide rod in a sliding mode, and the axis of the guide rod is perpendicular to the length direction of the plate spring;

the second shell is provided with a first groove, the guide rod is supported in the first groove, and the rack can slide in the first groove;

the movable sliding block is provided with rectangular teeth which are inclined compared with the guide rod, the rack is provided with a connecting groove, and the movable sliding block is connected to the rack in a sliding mode through the matching of the rectangular teeth on the movable sliding block and the connecting groove; the rotating central gear can drive the rack to slide on the guide rod, and the sliding rack drives the movable sliding block and the sliding seat to slide along the length direction of the plate spring so as to adjust the effective length of the plate spring to realize the change of joint rigidity.

2. The active variable stiffness joint based on a rack and pinion of claim 1 wherein the sliding base is a roller sliding base comprising a base body and two rollers, the base body is fixedly connected with the moving slider, and the two rollers are sleeved on the leaf spring.

3. The rack and pinion based active variable stiffness joint of claim 1 wherein the second housing has a second groove within which the moving slide is slidable.

4. The rack and pinion based active variable stiffness joint of claim 1 wherein the number of leaf springs is two or more, the two or more leaf springs being distributed around the input shaft array or on the mount in opposition.

5. The rack and pinion based active variable stiffness joint of claim 4 wherein the carriages on different leaf springs are the same distance from the input shaft.

6. The rack and pinion based active variable stiffness joint of claim 1 wherein the second housing is rotationally disposed within the first housing by two four point contact thin wall bearings.

7. The active variable stiffness joint based on a rack and pinion gear according to claim 1, wherein the variable stiffness adjustment assembly further comprises a pressure plate fixed on the second housing and a stiffness adjustment motor arranged on the pressure plate, and the central gear is arranged on an output shaft of the stiffness adjustment motor through a key connection.

8. The active variable stiffness joint based on the rack and pinion gear of claim 1, wherein the input control end further comprises a driving disc, the driving disc is fixedly connected with the first housing, the input rotating shaft is a stepped shaft, a mounting slot hole is formed in the driving disc, one end of the input rotating shaft is connected with the driving disc through a first bearing located in the mounting slot hole, and the other end of the input rotating shaft is connected with the second housing through a second bearing.

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