CN109465848B - Robot joint becomes rigidity module based on cam lever structure - Google Patents

Abstract

The invention discloses a robot joint rigidity-changing module based on a cam type lever structure, which comprises an input part, an output part and a rigidity adjusting part. The rigidity adjusting part comprises a pressure spring, a cam lever and a rigidity adjusting fulcrum; the cam lever rotates around the rigidity adjusting fulcrum, and one end of the cam lever is matched with the output part, and the other end of the cam lever is matched with the pressure spring. Bearings are provided between the input and output portions to bear the non-torque load of the entire module and to allow relative rotation of the input and output portions. When the output part of the variable stiffness module receives external transient load, the load is transmitted to the pressure spring through the cam lever to be absorbed, so that external impact is reduced, flexible driving output is realized, and meanwhile, the robustness and the operation stability of the robot are improved. The invention has compact structure and low cost and is integrated into one module, thus being convenient to be applied to various interactive equipment, in particular to flexible robot joints. The invention also has the advantages of convenient operation and easy implementation.

Description

A robot joint variable stiffness module based on cam lever structure

Technical field

The invention relates to the field of robots, and in particular to a robot joint stiffness variable module based on a cam lever structure.

Background technique

With the rapid development of modern industrial technology, the application scope of robots has expanded rapidly, and human-machine collaboration has become increasingly closer. With the continuous deepening of human-computer interaction, the working environment of robots has become complex and highly uncertain, and they may collide with objects and people in the surrounding environment at any time, which poses high challenges to the safety of robots. Require. For example, a robot needs to dynamically adjust joint stiffness and active/passive flexibility of robot joints according to changes in the external environment and its own load. Therefore, adding high-performance, compact variable stiffness mechanisms to collaborative robot joints to make the robot flexible has become a technical difficulty in the field of collaborative robots. Therefore, there is an urgent need for a batch of superior variable stiffness modules to promote the continuous development of collaborative robots.

At the same time, the robot industry is developing rapidly, with large demand and long design cycle. Therefore, the modular design idea is increasingly adopted in the field of robots. By decomposing the common functions of robots from the mechanism and control point of view, multiple functional modules with independent functions are formed. Through reconstruction, the robot structure required for the application is composed. type. This can reduce the application cost of robots, speed up research and development, and reduce research and development risks to a certain extent.

In terms of variable stiffness, domestic and foreign researchers have developed many variable stiffness mechanisms based on different principles. However, the existing variable stiffness design has some shortcomings, such as large size and weight, low versatility, or small stiffness adjustment range. In this case, it is difficult to apply to robot joints that have a compact structure, must be as light as possible, and have a wide stiffness adjustment range.

Today's existing technology uses two pairs of compression springs and a cam structure to achieve variable stiffness. The cam passively changes the compression amount of the spring and the motor actively changes the spring compression amount to change the stiffness. However, the lack of a stiffness amplification structure results in a smaller stiffness adjustment range, and the use of two pairs of compression springs also makes the variable stiffness rotary flexible joint larger in size.

Therefore, the existing technology needs to be further improved and perfected.

Contents of the invention

The object of the present invention is to overcome the shortcomings of the existing technology and provide a robot joint stiffness changer based on a cam lever structure that can reduce the external impact of the robot joint, achieve flexible drive output, and at the same time improve the robot's robustness and operational stability. module.

The object of the present invention is achieved through the following technical solutions:

A variable stiffness module of a robot joint based on a cam lever structure. The variable stiffness module mainly includes an input part, an output part, and a stiffness adjustment part. The output part is arranged within the input part. A bearing is provided between the input part and the output part to bear the non-torque load of the entire module and allow the input part and the output part to rotate relative to each other.

Specifically, the input part includes a housing and a housing bearing retaining ring. The housing bearing retaining ring is arranged on the housing and is fixedly connected to the housing. The outer shell is provided with a guide groove that restrains the compression spring and restrains the stiffness adjustment fulcrum. The guide groove is located at the bottom of the casing; the casing is provided with necessary mounting holes and lightening structures.

Specifically, the output part includes an output disk and an output disk bearing retaining ring. The output disk is arranged in the output disk bearing retaining ring and is concentrically arranged with the output disk bearing retaining ring. The bearing is arranged in the housing, its outer ring is fixedly connected to the housing bearing retaining ring, and the inner ring is connected to the output disk bearing retaining ring.

Specifically, the stiffness adjustment part includes a compression spring, a cam lever, a needle roller, a compression spring support, a compression spring mounting seat, a bushing, and a stiffness adjustment fulcrum. The stiffness adjustment fulcrum is fixed on the cam lever. The cam lever is set in the housing and can rotate around the stiffness adjustment fulcrum. One end of it is connected to the output disk through a sleeve, so that the output disk rotates with the cam lever when it rotates. The other end is in contact with the compression spring through a needle roller. . The needle roller is installed in the compression spring support, and its bottom is clamped in the guide groove and can move linearly in the guide groove. The compression spring mounting seat is fixed in the housing, one end of the compression spring is fixed on the compression spring mounting seat, and the other end is in contact with the compression spring support, forcing the roller needle to resist the cam lever. The compression spring and the roller needle are arranged in pairs on both sides of the cam lever and are arranged symmetrically.

Furthermore, in order to facilitate fine-tuning the stiffness of the robot joint, the stiffness adjustment part of the present invention also includes a stiffness adjustment bolt and a slider. The slide block is installed in a guide groove perpendicular to the axial direction of the compression spring and is fixedly connected to the stiffness adjustment fulcrum. The stiffness adjustment bolts are respectively arranged at the front and rear ends of the slider. One end of the stiffness adjustment bolt is matched with the slider and the other end goes out of the shell and is threadedly connected to the shell.

As a preferred solution of the present invention, in order to make the adjustment of the edge stiffness module more linear and achieve better effects, the two compression springs of the present invention are arranged oppositely on the same axis, and have the same compression amount in the initial position.

As a preferred solution of the present invention, in order to improve the fine-tuning effect of stiffness, the stiffness adjustment bolt of the present invention adopts a fine-thread bolt, and its pitch is set to 0.5 mm.

As a preferred solution of the present invention, in order to further limit the movement range of the needle roller and compression spring and achieve better stiffness adjustment effect, the front end of the compression spring support of the present invention is set into a U-shaped structure to catch the needle roller and push the roller The needle resists the outer circumferential surface of the cam lever, and the rear end is provided with a depression and cooperates with the compression spring to limit the end of the compression spring.

Furthermore, in order to prevent the stiffness adjustment bolt from protruding from the outer surface of the shell and affecting the range of motion of the robot joint, the connection between the stiffness adjustment bolt and the shell of the present invention is provided with a pit to facilitate hiding the adjustment fulcrum; the pit is The longitudinal section is rectangular.

The working process and principle of the present invention are: in actual operation, the variable stiffness module provided by the present invention is mainly used in robot joints. The shell of the variable stiffness module is installed on the reducer output end of the robot joint through bolts, and the output disk is fixed to the next joint through bolts. When disturbed by the external environment or a load is suddenly loaded onto the robot, the load passes through the output disk and the cam lever to the compression spring and the response to the load becomes supple, thus protecting the robot from damage and improving the operation of the robot. Stability etc. When the variable stiffness module takes effect, the output part and the stiffness adjustment lever will deflect at a certain angle relative to the equilibrium position, resulting in an increase in the compression of one compression spring and a decrease in the compression of the other compression spring. Through the force generated between the compression springs, The force balances the external load. The invention also has the advantages of simple structure, convenient operation and easy implementation.

Compared with the prior art, the present invention also has the following advantages:

(1) The robot joint stiffness variable module based on the cam lever structure provided by the present invention adopts the two-stage amplification effect of the cam lever and the output disk, so that it only needs to provide a small stiffness value against the spring to output a large stiffness value. , so the overall size of the entire variable stiffness module can be reduced.

(2) The compression spring provided in the variable stiffness module of the robot joint based on the cam lever structure provided by the present invention can buffer the externally applied load, thereby reducing the external impact of the robot joint, achieving flexible drive output, and improving the robot's robustness. Rodability and operational stability.

(3) The robot joint stiffness variable module based on the cam lever structure provided by the present invention innovatively uses the cam lever structure, and the stiffness of the module can be changed by simply changing the fulcrum position of the lever. Therefore, the number of parts of the variable stiffness mechanism can be greatly reduced, thereby achieving a compact structure, light weight, and a wide range of stiffness adjustment.

(4) The robot joint stiffness variable module based on the cam lever structure provided by the present invention adopts a modular design method, thereby reducing the application cost of the present invention to a certain extent and can be quickly applied to other equipment. For example, by cooperating with the output of a traditional reducer in a robot joint, the function of a series elastic driver can be realized.

(5) The robot joint stiffness variable module based on the cam lever structure provided by the present invention uses fine-thread bolts with a pitch of only 0.5 mm to adjust the fulcrum of the lever, which can not only ensure the fine-tuning of the stiffness, but also make use of the automatic fine-thread thread. The lockability ensures the invariance of the fulcrum position.

(6) The variable stiffness module of the robot joint based on the cam lever structure provided by the present invention changes the ratio of the resistance arm to the main force arm by changing the position of the fulcrum, so the stiffness value can be from zero to infinity.

Description of the drawings

Figure 1 is a schematic diagram of the overall structure of a robot joint variable stiffness module based on a cam lever structure provided by the present invention;

Figure 2 is a schematic diagram of the internal structure of the robot joint stiffness variable module based on the cam lever structure provided by the present invention;

Figure 3 is a partial structural schematic diagram of a robot joint stiffness variable module based on a cam lever structure provided by the present invention.

Description of the numbers in the above drawings:

1-input part, 2-output part, 3-stiffness adjustment part, 4-bearing, 11-casing, 12-casing bearing retaining ring, 21-output plate, 22-output plate bearing retaining ring, 31-cam lever, 32-axle sleeve, 33-needle roller, 34-compression spring support, 35-compression spring, 36-compression spring mounting seat, 37-stiffness adjustment bolt, 38-slider, 39-stiffness adjustment fulcrum.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention clearer and clearer, the present invention will be further described below with reference to the accompanying drawings and examples.

Example 1:

As shown in Figures 1 to 3, this embodiment discloses a robot joint variable stiffness module based on a cam lever structure. The variable stiffness module mainly includes an input part 1, an output part 2, and a stiffness adjustment part 3. The output part 2 is arranged within the input part 1 . A bearing 4 is provided between the input part 1 and the output part 2 to bear the non-torque load of the entire module and enable the input part 1 and the output part 2 to rotate relative to each other.

Specifically, the input part 1 includes a housing 11 and a housing bearing retaining ring 12 . The housing bearing retaining ring 12 is provided on the housing 11 and is fixedly connected to the housing 11 . The housing 11 is provided with a guide groove for constraining the compression spring 35 and constraining the stiffness adjustment fulcrum 39 . The guide groove is located at the bottom of the housing 11; the housing 11 is provided with necessary mounting holes and lightening structures.

Specifically, the output part 2 includes an output disk 21 and an output disk bearing retaining ring 22 . The output disk 21 is arranged in the output disk bearing retaining ring 22 and is concentrically arranged with the output disk bearing retaining ring 22 . The bearing 4 is arranged in the housing 11, its outer ring is fixedly connected to the housing bearing retaining ring 12, and its inner ring is connected to the output disk bearing retaining ring 22.

Specifically, the stiffness adjustment part 3 includes a compression spring 35 , a cam lever 31 , a needle roller 33 , a compression spring support 34 , a compression spring mounting seat 36 , a sleeve 32 , and a stiffness adjustment fulcrum 39 . The stiffness adjustment fulcrum 39 is fixed on the cam lever 31 . The cam lever 31 is arranged in the housing 11 and can rotate around the stiffness adjustment fulcrum 39. One end of the cam lever 31 is cooperatively connected with the output disk 21 through the sleeve 32, so that when the output disk 21 rotates, the cam lever 31 rotates, and the other end passes through The needle roller 33 is in contact with the compression spring 35 . The needle roller 33 is installed in the compression spring support 34, and its bottom is clamped in the guide groove, and can move linearly in the guide groove. The compression spring mounting base 36 is fixed in the housing 11. One end of the compression spring 35 is fixed on the compression spring mounting base 36, and the other end is in contact with the compression spring support 34, forcing the roller needle 33 to resist the cam lever 31. . The compression spring 35 and the needle roller 33 are arranged in pairs on both sides of the cam lever 31 and are arranged symmetrically.

Furthermore, in order to facilitate fine-tuning the stiffness of the robot joint, the stiffness adjustment part 3 of the present invention also includes a stiffness adjustment bolt 37 and a slider 38. The slider 38 is installed in a guide groove perpendicular to the axial direction of the compression spring 35 and is fixedly connected to the stiffness adjustment fulcrum 39 . The stiffness adjustment bolts 37 are respectively arranged at the front and rear ends of the slider 38 . One end of the stiffness adjustment bolts 37 is matched with the slider 38 , and the other end of the stiffness adjustment bolts 37 goes out of the housing 11 and is threadedly connected to the housing 11 .

As a preferred solution of the present invention, in order to make the adjustment of the edge stiffness module more linear and achieve better effects, the two compression springs 35 of the present invention are arranged oppositely on the same axis, and the compression springs 35 have the same compression in the initial position. quantity.

As a preferred solution of the present invention, in order to improve the fine-tuning effect of stiffness, the stiffness adjustment bolt 37 of the present invention adopts a fine-thread bolt, and its pitch is set to 0.5 mm.

As a preferred solution of the present invention, in order to further limit the movement range of the needle roller 33 and the compression spring 35 and achieve better stiffness adjustment effect, the front end of the compression spring support 34 of the present invention is set into a U-shaped structure to block the needle roller. 33 and press the roller needle 33 against the outer circumferential surface of the cam lever 31. The rear end is provided with a depression and cooperates with the compression spring 35 to limit the end of the compression spring 35.

Furthermore, in order to prevent the stiffness adjustment bolt 37 from protruding from the outer surface of the housing 11 and affecting the range of motion of the robot joint, the connection between the stiffness adjustment bolt 37 and the housing 11 is provided with a pit to facilitate hiding the adjustment fulcrum; The longitudinal section of the pit is rectangular.

The working process and principle of the present invention are: in actual operation, the variable stiffness module provided by the present invention is mainly used in robot joints. The shell 11 of the variable stiffness module is installed on the reducer output end of the robot joint through bolts, and the output disk 21 is fixed to the next joint through bolts. When disturbed by the external environment or a load is suddenly loaded onto the robot, the load passes through the output disk 21 and the cam lever 31 to the compression spring 35 and the response to the load becomes supple, thereby protecting the robot from damage and improving the performance of the robot. The operation stability of the robot, etc. When the variable stiffness module takes effect, the output part 2 and the stiffness adjustment lever will deflect at a certain angle relative to the equilibrium position, resulting in an increase in the compression of one compression spring 35 and a decrease in the compression of the other compression spring 35. Through the compression spring The force generated between 35 balances the external load. The invention also has the advantages of simple structure, convenient operation and easy implementation.

Example 2:

As shown in Figures 1 to 3, this embodiment discloses a robot joint stiffness variable module based on a cam lever structure, including an input part 1, an output part 2 and a stiffness adjustment part 3. The stiffness adjustment part 3 includes a compression spring 35, a cam lever 31 and a stiffness adjustment fulcrum 39; the cam lever 31 rotates around the stiffness adjustment fulcrum 39, and one end thereof cooperates with the output disk 21 and the other end cooperates with the compression spring 35. When an external load is loaded on the output disk 21 of the variable stiffness module, it is transmitted to the compression spring 35 through the action of the cam lever 31. At this time, the compression spring is compressed under the action of external force and causes the cam lever 31 to deflect at an angle. Due to the change in the angle of the cam lever 31, the output disk 21 is eventually deflected. This process is equivalent to when the variable stiffness module is subjected to a certain torque load, especially some sudden loads. After the action of the variable stiffness module, the compression spring 35 will generate a corresponding force to resist the sudden change of the load, thereby causing the The load response becomes softer. Under a certain external load, when the stiffness value of the module is large, the deflection angle value of the output disk 21 is small. On the contrary, when the stiffness value of the module is small, the deflection angle value of the output disk 21 will be larger, and the corresponding load response effect will be better. It is precisely because this process improves the robustness and operational stability of the robot and achieves the flexibility of the robot joints. A bearing 4 is provided between the input part 1 and the output part 2 to bear the non-torque load of the entire module and enable the input part 1 and the output part 2 to rotate relative to each other. Non-torque loads are filtered out through the action of bearing 4 to ensure that only torque loads are loaded into the variable stiffness joint.

In the specific technical solution of the present invention, the input part 1 includes a module shell 11 and a bearing retaining ring 12. The shell 1 is provided with a guide groove for constraining the compression spring and the stiffness adjustment fulcrum. At the same time, the shell 1 is provided with the necessary The installation hole positions and lightening structure. Through the action of the guide groove, the compression spring 35 and the stiffness adjustment fulcrum 39 are restricted from reciprocating in a straight line. The output part 2 includes an output disk 21 and a bearing retaining ring 22 . The bearing 4 is respectively fixed on the housing 11 and the output disk 21 through bearing retaining rings.

In the specific technical solution of the present invention, the two compression springs 35 are arranged oppositely on the same axis and have the same compression amount in the initial position. By using two compression springs arranged oppositely with the same amount of compression, the mechanism can automatically return to the neutral point, and the stiffness value will be doubled compared to the solution of a single compression spring 35 . One end of the compression spring 35 is fixed with a mounting base 36, and the compression spring mounting base 36 is fixed on the housing 11 to ensure the position of the compression spring 35; the other end of the compression spring 35 is also fixed with a limiter that restricts the compression spring to only be in the housing guide groove. There is a moving compression spring support 34, and a mounting hole for the needle roller 33 is provided on the compression spring support 34. The design of guide grooves and needle rollers used in this part fully compresses the structural space and ensures the compactness of the entire variable stiffness module.

In the specific technical solution of the present invention, a sleeve 32 is used at one end of the cam lever 31 to cooperate with the output part 2, and a needle roller 33 is used at the other end of the cam lever 31 to cooperate with the compression spring 35. One end of the lever is provided with a boss to cooperate with the hole of the output plate 21, and a sleeve 32 is used to reduce friction in the middle; the cam at the other end contacts and cooperates with the needle roller 33 installed in the hole of the support 34. The design of the shaft sleeve is also one of the better designs in this technical solution. It ensures smooth rotation between the output disk 21 and the boss provided on the cam lever 31, and also improves the load-bearing capacity.

In the specific technical solution of the present invention, the stiffness adjustment bolt 39 is installed on the slider 38 and its position can be adjusted manually. The slider 38 is installed in the guide groove of the housing 11, and the position of the slider 38 is adjusted and fixed by two fine thread bolts 37. By using a fine-thread bolt with a pitch of 0.5mm, the stiffness adjustment bolt 39 only moves 0.5mm after one rotation of the adjustment bolt, ensuring fine-tuning of the stiffness adjustment. At the same time, since the fit between the fine threads is self-locking, it can be ensured that the stiffness adjustment bolt 39 does not change during operation.

Referring to Figures 1 to 3, it should be further explained that in actual work, this module is mainly used in robot joints. The shell 11 of the variable stiffness module is installed on the reducer output end of the robot joint through bolts, and the output disk 21 is fixed to the next joint through bolts. When disturbed by the external environment or a load is suddenly loaded onto the robot, the load passes through the output disk 21 and the cam lever 31 to the compression spring 35 and the response to the load becomes supple, thereby protecting the robot from damage and improving the performance of the robot. The operation stability of the robot, etc. When the variable stiffness module takes effect, the output part 2 and the stiffness adjustment lever 31 will deflect at a certain angle relative to the equilibrium position, resulting in an increase in the compression of one compression spring 35 and a decrease in the compression of the opposite compression spring 35. The force generated between the springs 35 balances the external load.

It should be further explained that in the technical solution of this embodiment, when the stiffness of the robot needs to be adjusted, the slider 38 can be adjusted to an appropriate position by rotating the two fine-thread bolts 37 so that the module stiffness reaches the required value. Then tighten the two fine thread bolts 37 to ensure that the position of the slider 38 does not change.

When designing, it should be noted that the number of compression springs should not be limited to the two in the embodiment. Other numbers are also feasible. Considering that the structure is as compact as possible, the two compression springs in the embodiment are more appropriate. , if you need to increase the load, you can consider increasing the number of compression springs; in the stiffness adjustment method, the embodiment also considers the manual form to make the structure as compact as possible. When the size requirements are not very high, the electric form can be used. Adjust the stiffness in the form.

It should be noted that the embodiment shown in FIGS. 1 to 3 is only a preferred embodiment introduced by the present invention, and those skilled in the art can design more embodiments based on this. The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be practiced in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, etc. may be made without departing from the spirit and principles of the present invention. All simplifications should be equivalent substitutions, and are all included in the protection scope of the present invention.

Claims (4)

1. The robot joint rigidity-changing module based on the cam lever structure is characterized by comprising an input part, an output part and a rigidity adjusting part; the output portion is disposed within the input portion; a bearing is arranged between the input part and the output part so as to bear the non-torque load of the whole module and enable the input part and the output part to rotate relatively;

the input part comprises a shell and a shell bearing retainer ring; the shell bearing retainer ring is arranged on the shell and fixedly connected with the shell; the shell is internally provided with a guide groove for restraining the compression spring and the rigidity adjusting fulcrum; the guide groove is positioned at the bottom of the shell; the shell is provided with necessary mounting hole sites and a lightening structure;

the output part comprises an output disc and an output disc bearing retainer ring; the output disc is arranged in the output disc bearing retainer ring and is concentric with the output disc bearing retainer ring; the bearing is arranged in the shell, the outer ring of the bearing is fixedly connected with the shell bearing retainer ring, and the inner ring of the bearing is connected with the output disc bearing retainer ring;

the rigidity adjusting part comprises a pressure spring, a cam lever, a needle roller, a pressure spring support, a pressure spring mounting seat, a shaft sleeve and a rigidity adjusting fulcrum; the rigidity adjusting fulcrum is fixed on the cam lever; the cam lever is arranged in the shell and can rotate around the rigidity adjusting fulcrum, one end of the cam lever is connected with the output disc in a matched manner through the shaft sleeve, so that the output disc rotates with the cam lever when rotating, and the other end of the cam lever is abutted with the pressure spring through the needle roller; the rolling pin is arranged in the pressure spring support, the bottom of the rolling pin is clamped in the guide groove and can linearly move in the guide groove; the compression spring mounting seat is fixed in the shell, one end of the compression spring is fixed on the compression spring mounting seat, and the other end of the compression spring is abutted with the compression spring support to force the needle roller to abut against the cam lever; the pressure springs and the rolling pins are arranged on two sides of the cam lever in pairs and are symmetrically arranged;

the rigidity adjusting part further comprises a rigidity adjusting bolt and a sliding block; the sliding block is arranged in a guide groove which is axially vertical to the pressure spring and is fixedly connected with the rigidity adjusting fulcrum; the rigidity adjusting bolts are respectively arranged at the front end and the rear end of the sliding block, one end of each rigidity adjusting bolt is connected with the sliding block in a matched mode, and the other end of each rigidity adjusting bolt penetrates out of the shell and is in threaded connection with the shell;

the two compression springs are arranged on the same axis in a relative mode, and have the same compression amount when in an initial position.

2. The robot joint stiffness varying module based on cam type lever structure according to claim 1, wherein the stiffness adjusting bolt is a fine tooth bolt with a pitch set to 0.5 mm.

3. The robot joint stiffness changing module based on the cam type lever structure according to claim 1, wherein the front end of the pressure spring support is of a U-shaped structure to clamp the rolling pin and support the rolling pin against the outer circumferential surface of the cam type lever, and the rear end of the pressure spring support is provided with a recess and is matched with the pressure spring to limit the end part of the pressure spring.

4. The robot joint stiffness changing module based on the cam type lever structure according to claim 1, wherein a pit which is convenient for hiding an adjusting fulcrum is arranged at the joint of the stiffness adjusting bolt and the shell; the longitudinal section of the pit is rectangular.