End effector

Abstract

The end effector provided by the present invention includes a housing, a motion shaft disposed within the housing, a first elastic disc, a second elastic disc, and a prestress adjustment screw sleeved on the motion shaft. Among them, an end cover is provided at the top of the housing, and the end cover is connected to the prestress adjustment screw. Among them, the prestress of the first elastic disc is adjusted by the prestress adjustment screw. Both the first elastic disc and the second elastic disc are centrosymmetric structures. One end of the first elastic disc and the second elastic disc is respectively fixed on the motion shaft, and the other end of the first elastic disc and the second elastic disc is respectively fixed on the inner wall of the housing. The first elastic disc and the second elastic disc move driven by the motion shaft. By using the present invention, problems such as poor control accuracy, poor real-time performance, and high cost of current robot end effectors can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of robots, and more specifically, to an end effector of a robot. Background Art

[0002] Currently, robots mainly use pneumatic devices as end effectors, and in some cases, electric-driven end effectors are also used. The current pneumatic and electric end effectors only achieve simple opening and closing, or displacement during the action process. In the fields of precision electronic device insertion, fine grinding, space station equipment maintenance, etc., the end effector of the robot must maintain a constant acting force during the action process; when the end effector uses force control or force-position hybrid control with a contact force sensor in the loop, it is difficult for the sensor to process the collected signals in a vibrating or harsh environment, resulting in poor control accuracy and real-time performance.

[0003] In addition, due to the gaps, motion delays, and a certain degree of flexibility in each joint of the multi-joint robot, it is also difficult to compensate in real time even if an accurate value of the end load deviation is obtained. In addition, the price of the multi-dimensional force sensor used in conjunction with the end effector is high, even close to the price of the robot body, so it is difficult to be widely used.

[0004] To solve the above problems, the present invention urgently needs to provide a new end effector. Summary of the Invention

[0005] In view of the above problems, the object of the present invention is to provide an end effector to solve the problems of poor control accuracy, poor real-time performance, and high cost of the current robot end effector.

[0006] The end effector provided by the present invention includes a housing, a motion shaft disposed in the housing, a first elastic disk, a second elastic disk, and a prestress adjustment screw sleeved on the motion shaft. Among them,

[0007] A end cover is provided at the top of the housing, and the end cover is connected to the prestress adjustment screw; wherein, the prestress of the first elastic disk is adjusted by the prestress adjustment screw.

[0008] Both the first elastic disk and the second elastic disk are centrosymmetric structures. One end of the first elastic disk and the second elastic disk is respectively fixed on the motion shaft, and the other end of the first elastic disk and the second elastic disk is respectively fixed on the inner wall of the housing. The first elastic disk and the second elastic disk move under the drive of the motion shaft.

[0009] In addition, a preferred structure is that the second elastic disk is a bistable elastic disk, wherein,

[0010] When the bistable elastic disc is in the first stable state position, the fixed point of the bistable elastic disc on the moving shaft is higher than the fixed point of the bistable elastic disc on the inner wall of the housing.

[0011] When the bistable elastic disc is in the second stable state position, the fixed point of the bistable elastic disc on the moving shaft is lower than the fixed point of the bistable elastic disc on the inner wall of the housing.

[0012] In addition, a preferred structure is that the first elastic disc and the second elastic disc are connected in parallel through the moving shaft, and the stiffness of the moving shaft relative to the housing is the sum of the elastic coefficients of the two elastic discs.

[0013] In addition, a preferred structure is that when the stiffness of the moving shaft relative to the housing is zero, the load along the moving shaft remains unchanged.

[0014] In addition, a preferred structure is that it further includes a spring sleeved on the moving shaft, where

[0015] the spring is a corrugated spring, and the corrugated spring is limited between the prestress adjustment screw and the first elastic disc, where

[0016] the corrugated spring is compressed by rotating the prestress adjustment screw to adjust the prestress of the first elastic disc.

[0017] In addition, a preferred structure is that the end cover is connected to the prestress adjustment screw by a thread.

[0018] In addition, a preferred structure is that three bushings are provided on the inner side of the housing, where

[0019] the two elastic discs fixed on the inner wall of the housing are spaced apart by the three bushings.

[0020] In addition, a preferred structure is that a limiting shoulder is provided below the moving shaft, and a flange adapted to the limiting shoulder is provided at the center position of the lower end of the housing, where

[0021] the limiting shoulder is used to limit the movement range of the moving shaft and prevent the structure of the end effector from being damaged due to excessive load on the moving shaft;

[0022] the flange is used to guide the moving shaft.

[0023] In addition, a preferred structure is that mounting holes are provided at the edge position of the lower end of the housing, and the housing is fixedly installed with other components through the mounting holes.

[0024] As can be seen from the above technical solution, the end effector provided by the present invention has a rotary body structure. A moving shaft is provided in the housing, and two elastic discs, a spring and a prestress adjusting screw are sleeved on the moving shaft. Among them, the spring is limited between the prestress adjusting screw and the elastic disc, and the spring is compressed by rotating the prestress adjusting screw to adjust the prestress of the elastic disc; both elastic discs are centrosymmetric structures, one end of the two elastic discs is fixed on the moving shaft, and the other end of the two elastic discs is fixed on the inner wall of the housing, and the two elastic discs move driven by the moving shaft. The constant force of the end effector of the present invention remains unchanged, and does not include links and devices such as sensors, data acquisition and processing, calculation and feedback control, etc., so the structure is simple and the cost is low.

[0025] To achieve the above and related purposes, one or more aspects of the present invention include features that will be described in detail later. The following description and the accompanying drawings detail certain exemplary aspects of the present invention. However, these aspects merely indicate some of the various ways in which the principles of the present invention can be used. In addition, the present invention is intended to include all these aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] By referring to the following description in conjunction with the accompanying drawings and the content of the claims, and with a more comprehensive understanding of the present invention, other objects and results of the present invention will become more apparent and easier to understand. In the drawings:

[0027] Figure 1 is a schematic cross-sectional structure diagram of an end effector according to an embodiment of the present invention;

[0028] Figure 2 is a schematic diagram showing the relationship between the displacement of the moving shaft and the load at point A according to an embodiment of the present invention;

[0029] Figure 3 is a schematic diagram showing the second stable position of a bistable disc according to an embodiment of the present invention;

[0030] Figure 4 is a schematic diagram showing the relationship between the displacement of the moving shaft and the load at point B according to an embodiment of the present invention;

[0031] Figure 5 is a schematic diagram showing the relationship between the displacement of the moving shaft and its load according to an embodiment of the present invention;

[0032] Figure 6 is a schematic diagram showing the principle of changing the constant force by adjusting the pre-tightening force according to an embodiment of the present invention;

[0033] Figure 7 is a schematic diagram showing the installation and working of an end effector according to an embodiment of the present invention;

[0034] Figure 8Schematic diagram of the three-dimensional structure of the end effector according to an embodiment of the present invention;

[0035] Figure 9 Schematic diagram of the partially cut-away structure of the end effector according to an embodiment of the present invention.

[0036] The reference numerals therein include: 1, housing; 2, motion shaft; 3, prestress adjustment screw; 4, end cap; 5, spring; 6, first bushing; 7, first elastic disc; 8, second bushing; 9, second elastic disc; 10, limiting shoulder; 11, third bushing; 12, mounting hole; 13, flange; 14, end effector; 15, robot; 16, workpiece.

[0037] In all the drawings, the same reference numerals indicate similar or corresponding features or functions. Detailed implementation manners

[0038] In view of the problems of poor control accuracy, poor real-time performance, and high cost of the current robot end effector mentioned above, the present invention provides an end effector.

[0039] The following will describe in detail the specific embodiments of the present invention with reference to the drawings.

[0040] To illustrate the structure of the end effector provided by the present invention, Figure 1 、 Figures 7 to 9 The structure of the end effector is exemplarily labeled from different angles. Specifically, Figure 1 shows the sectional structure of the end effector according to an embodiment of the present invention; Figure 7 shows the installation and operation of the end effector according to an embodiment of the present invention; Figure 8 shows the three-dimensional structure of the end effector according to an embodiment of the present invention; Figure 9 shows the partially cut-away structure of the end effector according to an embodiment of the present invention.

[0041] As Figure 1 、 Figures 7 to 9 collectively show, the end effector provided by the present invention includes: a housing 1, a motion shaft 2 disposed in the housing 1, two elastic discs (the first elastic disc 7 and the second elastic disc 9) sleeved on the motion shaft 2, a spring 5, and a prestress adjustment screw 3. Among them, an end cap 4 is provided at the top of the housing 1, and the end cap 4 is connected to the prestress adjustment screw 3 by a thread; wherein, the spring 5 is limited between the prestress adjustment screw 3 and the two elastic discs, and by rotating the prestress adjustment screw 3, the spring 5 is compressed to adjust the prestress of the two elastic discs; both of the two elastic discs are centrosymmetric structures, one end of each of the two elastic discs is fixed on the motion shaft 2, and the other end of each of the two elastic discs is fixed on the inner wall of the housing 1, and the two elastic discs move driven by the motion shaft 2.

[0042] Among them, the two elastic discs include a first elastic disc 7 and a second elastic disc 9, and the second elastic disc 9 is a bistable elastic disc. When the bistable elastic disc is in the first stable position, the fixed point of the bistable elastic disc on the moving shaft 2 is higher than the fixed point of the bistable elastic disc on the inner wall of the housing 1. When the bistable elastic disc is in the second stable position, the fixed point of the bistable elastic disc on the moving shaft 2 is lower than the fixed point of the bistable elastic disc on the inner wall of the housing 1.

[0043] Among them, the first elastic disc 7 and the second elastic disc 9 are connected in parallel through the moving shaft 2. The stiffness of the moving shaft 2 relative to the housing 1 is the sum of the elastic coefficients of the two elastic discs. Among them, the elastic coefficient of the first elastic disc 7 is positive, and the elastic coefficient of the second elastic disc 9 is negative. When the stiffness of the moving shaft 2 relative to the housing 1 is zero, the load along the moving shaft 2 remains unchanged.

[0044] Among them, the spring 5 is a corrugated spring, and the corrugated spring is limited between the prestress adjustment screw 3 and the first elastic disc 7. Among them, the corrugated spring is compressed by rotating the prestress adjustment screw 3 to adjust the prestress of the first elastic disc 7.

[0045] Among them, three bushings are arranged on the inner side of the housing 1. Among them, the two elastic discs fixed on the inner wall of the housing 1 are spaced apart by the three bushings. In Figure 1 In the illustrated embodiment, the three bushings are a first bushing 6, a second bushing 8, and a third bushing 11 respectively. Among them, the other end D of the first elastic disc 7 is fixed between the first bushing 6 and the second bushing 8, and the other end E of the second elastic disc 9 is fixed between the second bushing 8 and the third bushing 11. Among them, in Figure 1 In the illustrated embodiment, one end A of the first elastic disc 7 and one end B of the second elastic disc 9 are both fixed on the moving shaft 2.

[0046] Among them, a limiting shoulder 10 is arranged below the moving shaft 2, and a flange 13 adapted to the limiting shoulder 10 is arranged at the central position of the lower end of the housing 1. Among them, the limiting shoulder 10 is used to limit the movement range of the moving shaft 2 to prevent the structure of the end effector from being damaged due to excessive load on the moving shaft 2. Among them, the flange 13 is used to guide the moving shaft 2; an installation hole 12 is arranged at the edge position of the lower end of the housing 1, and the housing 1 is installed and fixed to other components through the installation hole 12.

[0047] In the embodiment of the present invention, the working principle of the end effector is as follows: the stiffness of the first elastic disc is positive, that is, when the moving shaft moves downward within a certain range, the greater the axial displacement, the greater the force acting at the connection (at point A) between the moving shaft and the first elastic disc. As Figure 2 The schematic diagram of the relationship shows the relationship between the displacement of the moving shaft and the load at point A.

[0048] Among them, the second elastic disk is a bistable elastic disk, and the bistable elastic disk has two stable positions. After the moving shaft is loaded and moves downward, the bistable elastic disk will reach the second stable position, and the specific position Figure 3 is shown. As Figure 4 shown, during the process of the bistable elastic disk reaching the second stable position, within a certain displacement range, the greater the axial displacement, the smaller the force acting on the connection (at point B) between the moving shaft and the bistable elastic disk, that is, the bistable elastic disk has a negative stiffness in this region.

[0049] In the embodiment of the present invention, the first elastic disk and the bistable elastic disk Figure 1 are simplified into a spring model. Then, these two springs are connected in parallel through the moving shaft, and the stiffness of the moving shaft relative to the housing is the sum of the elastic coefficients of the two springs. Let the elastic coefficient of the first elastic disk be K1, and the elastic coefficient of the bistable elastic disk be K2. Within a certain displacement range (such as Figure 2 , 4 , the region between X1 and X2 in 5), K1 is positive, K2 is negative, then the stiffness of the moving shaft relative to the housing is K = K1 + K2, and there is a case where K is equal to 0, as Figure 5 shown. When the stiffness K is equal to 0, that is, in the approximate zero-stiffness region, during the up and down movement of the moving shaft, the axial load remains unchanged, so as to realize that the end effector maintains a constant force. To ensure that the approximate zero-stiffness region corresponds to a relatively large displacement range, the material, variable cross-section, etc. of the bistable elastic disk need to be selected according to the specific design of the first elastic disk. In the embodiment of the present invention, to make the constant force maintained by the end effector adjustable, the prestress adjustment screw 3 on the end cap 4 can be rotated to compress or relax the spring 5, so as to adjust the prestress acting on the first elastic disk 7, and then change the approximate zero-stiffness region and its corresponding constant load, and the schematic diagram of the specific relationship is as Figure 6 shown in the region from X3 to X4 in.

[0050] In a specific embodiment of the present invention, the stiffness of the moving shaft 2 relative to the housing 1 is the sum of the elastic coefficients of the two elastic disks, that is: the sum of the elastic coefficients is the addition of the elastic coefficient of the first elastic disk and the elastic coefficient of the second elastic disk. In the embodiment of the present invention, by rotating the prestress adjustment screw on the end cap to compress or relax the spring, the prestress of the first elastic disk is adjusted so that the sum of the elastic coefficients is zero, so as to realize that the end effector maintains a constant force.

[0051] In Figure 7In the illustrated embodiment, the housing of the end effector 14 is positioned and fixed to the end flange of the robot 15 through the mounting holes, and the moving axes in the end effector 14 act on the surface of the workpiece 16. Since both the first elastic disc and the bistable elastic disc are centrosymmetric structures, when the end effector 14 is working, tangential forces within a certain range in any direction in the plane of the contact surface can be balanced, ensuring that the end of the robot 15 moves on the surface of the workpiece 16 along a predetermined trajectory.

[0052] As can be seen from the above embodiments, the end effector provided by the present invention has a rotary body structure. A moving axis is provided in the housing, and two elastic discs, springs, and prestress adjustment screws are sleeved on the moving axis. Among them, the springs are limited between the prestress adjustment screws and the elastic discs, and the prestress of the elastic discs is adjusted by rotating the prestress adjustment screws to compress the springs; both of the two elastic discs are centrosymmetric structures. One end of the two elastic discs is fixed on the moving axis, and the other end of the two elastic discs is fixed on the inner wall of the housing. The two elastic discs move driven by the moving axis. The constant force of the end effector of the present invention remains unchanged, and it does not include components and devices such as sensors, data acquisition and processing, calculation, and feedback control. Therefore, the structure is simple and the cost is low.

[0053] As described above by way of example with reference to the drawings, the end effector proposed according to the present invention has been described. However, those skilled in the art should understand that various improvements can be made to the above-mentioned end effector of the present invention without departing from the content of the present invention. Therefore, the protection scope of the present invention should be determined by the content of the appended claims.

Claims

1. An end effector, characterized in that, It includes a housing, a motion shaft disposed within the housing, a first elastic disc, a second elastic disc and a prestress adjustment screw sleeved on the motion shaft, and a spring sleeved on the motion shaft. The spring is a corrugated spring, and the corrugated spring is limited between the prestress adjustment screw and the first elastic disc. Among them, a end cap is provided at the top of the housing, and the end cap is connected to the prestress adjustment screw; among them, by rotating the prestress adjustment screw, the corrugated spring is compressed to adjust the prestress of the first elastic disc; both the first elastic disc and the second elastic disc are centrosymmetric structures. One end of the first elastic disc and the second elastic disc is respectively fixed on the motion shaft, and the other end of the first elastic disc and the second elastic disc is respectively fixed on the inner wall of the housing. The first elastic disc and the second elastic disc move driven by the motion shaft; the first elastic disc and the second elastic disc are connected in parallel through the motion shaft, and the stiffness of the motion shaft relative to the housing is the sum of the elastic coefficients of the two elastic discs.

2. The end effector according to claim 1, characterized in that, The second elastic disc is a bistable elastic disc, among which, when the bistable elastic disc is in the first stable position, the fixed point of the bistable elastic disc on the motion shaft is higher than the fixed point of the bistable elastic disc on the inner wall of the housing; when the bistable elastic disc is in the second stable position, the fixed point of the bistable elastic disc on the motion shaft is lower than the fixed point of the bistable elastic disc on the inner wall of the housing.

3. The end effector according to claim 1, characterized in that, When the stiffness of the motion shaft relative to the housing is zero, the load along the motion shaft remains unchanged.

4. The end effector according to claim 1, characterized in that, The end cap is connected to the prestress adjustment screw by a thread.

5. The end effector according to claim 1, characterized in that, Three bushings are provided on the inner side of the housing, among which, the two elastic discs fixed on the inner wall of the housing are spaced apart by the three bushings.

6. The end effector according to claim 1, characterized in that, A limiting shoulder is provided below the motion shaft, and a flange adapted to the limiting shoulder is provided at the center position of the lower end of the housing. Among them, the limiting shoulder is used to limit the movement range of the motion shaft to prevent the motion shaft from being damaged due to excessive load and destroying the structure of the end effector; the flange is used to guide the motion shaft.

7. The end effector according to claim 1, characterized in that, An installation hole is provided at the edge position of the lower end of the housing, and the housing is fixedly installed with other components through the installation hole.

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