CN111595505B

CN111595505B - Axial force sensor assembly, robot clamping jaw and robot

Info

Publication number: CN111595505B
Application number: CN202010598427.1A
Authority: CN
Inventors: 姜皓; 常今朝; 王世全
Original assignee: Feixi Technology Co ltd; Flexiv Robotics Ltd
Current assignee: Feixi Technology Co ltd; Flexiv Robotics Ltd
Priority date: 2020-06-28
Filing date: 2020-06-28
Publication date: 2022-07-08
Anticipated expiration: 2040-06-28
Also published as: CN111595505A

Abstract

The invention provides an axial force sensor assembly for detecting an axial force, comprising a mounting frame and a first sensor mounted on the mounting frame. The mounting bracket includes an inner mounting portion, an outer mounting portion, and a multi-layered connecting member connected between the inner mounting portion and the outer mounting portion, the multi-layered connecting member being more compliant in the axial force direction than in other load directions. The first sensor is configured to detect a relative displacement between the inner and outer mounts in the axial force direction.

Description

Axial force sensor assembly, robot clamping jaw and robot

Technical Field

The present invention relates to a sensing member, and more particularly, to an axial force sensor assembly, a robot gripping jaw having the axial force sensor assembly, and a robot having the robot gripping jaw.

Background

Most of the conventional force sensors use strain gauges to detect local strain of a structure that is deformed by a load. These sensors use contact-based resistive strain sensors that are attached to a deformable structure to measure the deformation of the structure by detecting changes in electrical resistance. However, deformable structures are inherently sensitive to temperature changes, contact with the bonding material, complex stresses in all directions, stress concentrations, and impact loads. Non-contact based force sensors use capacitive, inductive or optical transducers to capture the overall displacement caused by structural deformation under load, thereby eliminating some of the disadvantages of strain gauge sensors related to resistance sensing, localized stress and adhesion issues. However, most non-contact based force sensors may be sensitive to off-axis load induced noise because it is difficult to manufacture structures that deform only under loads in a particular direction (e.g., axial forces) while being well able to resist loads in other directions (e.g., bending moments).

Disclosure of Invention

The application aims at providing an improved axial force sensor assembly, a robot clamping jaw and a robot.

One aspect of the present application provides an axial force sensor assembly for detecting an axial force, comprising: a mounting bracket including an inner mounting portion, an outer mounting portion, and a multi-layered connecting member connected between the inner mounting portion and the outer mounting portion, the multi-layered connecting member being more compliant in an axial force direction than in other load directions; and a first sensor mounted on the mounting bracket and configured to detect a relative displacement between the inner and outer mounting portions in an axial force direction.

In one embodiment, the multi-layer connection includes a first diaphragm and a second diaphragm located at different positions in the axial force direction.

In one embodiment, a distance between the first diaphragm and the second diaphragm in the axial force direction is greater than or equal to 6 times the inner mount diameter.

In one embodiment, the first and second diaphragms are identical in structure and parallel to each other.

In one embodiment, the first diaphragm includes a plurality of first connecting members circumferentially distributed about the inner mounting portion, and the second diaphragm includes a plurality of second connecting members circumferentially distributed about the inner mounting portion, each of the first and second connecting members connecting the inner and outer mounting portions.

In one embodiment, at least part of the first connection and at least part of the second connection are aligned with each other in the axial force direction.

In one embodiment, each of the first and second connectors has a length greater than its thickness.

In one embodiment, each of the first and second connectors has a substantially straight beam structure extending in a radial direction of the axial force sensor assembly.

In one embodiment, a second sensor is also included, the first sensor and the second sensor being configured to have opposite signal trends when the axial force sensor assembly is subjected to an axial force.

In one embodiment, the first sensor is disposed closer to the inner mount than to the outer mount.

Another aspect of the present application provides a robot gripping jaw comprising a gripping device and an axial force sensor assembly as in the above embodiments, the axial force sensor assembly being configured to detect an axial force exerted by the gripping device.

A further aspect of the application provides a robot comprising a robot gripping jaw as described above.

Drawings

These and other features of the present application will be more readily understood from the following detailed description of the various aspects of the present application taken in conjunction with the accompanying drawings that depict various embodiments of the application, in which:

FIG. 1 is a perspective view of an axial force sensor assembly according to one embodiment of the present invention;

FIG. 2 is an exploded view of the axial force sensor assembly of FIG. 1;

FIG. 3 is a perspective view of a mounting bracket of one embodiment of the present invention;

FIG. 4 is a side view of a mounting bracket of one embodiment of the present invention;

FIG. 5 is a cross-sectional view of the mounting bracket taken along line A-A of FIG. 3;

FIG. 6 is a schematic view of an axial force sensor assembly according to one embodiment of the present invention when subjected to an axial force;

FIG. 7 is a schematic view of an axial force sensor assembly according to one embodiment of the present invention when subjected to a bending moment;

FIG. 8 is a schematic view of an axial force sensor assembly according to another embodiment of the present invention when subjected to a bending moment;

FIG. 9 is a schematic view of an axial force sensor assembly according to one embodiment of the present invention when subjected to a shear force;

FIG. 10 is a schematic view of an axial force sensor assembly according to one embodiment of the present invention when subjected to a torque.

It is noted that the drawings of the present application are not to scale. The drawings are intended to depict only typical aspects of the application, and should not be considered as limiting the scope of the application.

Detailed Description

Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

Referring to fig. 1-5, one aspect of the present application provides an axial force sensor assembly 10 that includes a mounting bracket 20 and a first sensor 30 mounted on the mounting bracket 20. The mount 20 is made primarily of one or more linear materials, such as metal, plastic, or rubber. The mounting bracket 20 includes an outer mounting portion 21, an inner mounting portion 22, and a multi-layered connecting member 23 connected between the inner mounting portion 22 and the outer mounting portion 21. The first sensor 30 is configured to detect a relative displacement between the inner mounting part 22 and the outer mounting part 21 in the direction of the axial force to be detected, i.e. in the axial direction of the axial force sensor assembly 10. The multi-layered linkage 23 is more compliant in the axial force direction than in other load directions. In particular, the multi-layered connector 23 is sensitive to axial forces, such that the axial force sensor assembly 10 is more susceptible to relative displacement between the inner and

outer mounting portions

22, 21 when subjected to axial forces than to forces or moments in other directions.

According to the axial force sensor assembly 10 of the embodiment of the application, because the multilayer connecting piece 23 is adopted, and the multilayer connecting piece 23 is connected between the inner mounting part 22 and the outer mounting part 21, when the axial force sensor assembly 10 is subjected to an axial load or an axial force, the inner mounting part 22 and the outer mounting part 21 generate relative displacement, and the first sensor 30 can effectively detect the relative displacement, so that the detection of the axial force is realized. At the same time, the multi-layered linkage 23 may inhibit, at least to some extent, relative displacement between the inner and

outer mounting portions

22, 21 caused by non-axial forces, such as off-axis (off-axis) forces or torque.

Referring now to FIG. 3 with emphasis on the construction of the components, the axial force sensor assembly 10 defines a three-dimensional coordinate system thereon that includes an axial force direction, i.e., the Z direction, and two radial directions, i.e., the X direction and the Y direction. The three directions are perpendicular to each other.

In one embodiment, the multi-layer connection 23 may be, for example, a two-layer structure including a first membrane 24 and a second membrane 25. The first diaphragm 24 and the second diaphragm 25 are located at different positions in the direction of the axial force to be detected, i.e. in the direction of the axis Z of the axial force sensor assembly shown in fig. 3. The multi-layer connector 23 may be integrally formed with the inner and

outer mounting portions

22 and 21, or may be a separate component assembled to the inner and

outer mounting portions

22 and 21. It should be understood that the multi-layer connector 23 may have a greater number of layers in other embodiments, for example, it may be a three-layer or four-layer structure.

The first diaphragm 24 may further include a plurality of first connectors 240, the second diaphragm 25 may further include a plurality of second connectors 250, the first and

second connectors

240 and 250 are respectively circumferentially distributed around the inner mount 22, and each of the first and

second connectors

240 and 250 connects the inner mount 22 and the outer mount 21. In the embodiment shown in fig. 3, the first diaphragm 24 and the second diaphragm 25 each comprise four radially extending connecting members.

In one embodiment, the first diaphragm 24 and the second diaphragm 25 are identical in construction, parallel to each other, and at least a portion of the first linkage 240 and at least a portion of the second linkage 250 are aligned with each other in the axial force direction. In some embodiments, as shown in fig. 3, all of the first connectors 240 and the second connectors 250 are respectively aligned in correspondence in the axial force direction.

In one embodiment, the first and

second connectors

240 and 250 are flat structures, and each of the first and

second connectors

240 and 250 has a length substantially greater than a thickness, wherein the length is in a radial direction and the thickness is in an axial force direction. Each first connector 240 and each second connector 250 has a substantially straight beam structure extending in a radial direction, in this embodiment the first connector 240 and the second connector 250 are designed to be sensitive to axial forces and resistant to radial forces.

FIG. 6 is a schematic view of an axial force sensor assembly 10 according to one embodiment of the present application when subjected to an axial force. When the inner mounting portion 22 is subjected to an axial force F_ZAt this time, the double-layered membrane structure is low in rigidity due to the bending-prone effect, the first diaphragm 24 and the second diaphragm 25 are deformed, and a relative displacement is generated between the inner mounting portion 22 and the outer mounting portion 21. This relative displacement may be detected by the first sensor 30. Specifically, the first connection 240 of the first diaphragm 24 and the second connection 250 of the second diaphragm 25 have a thin elongated structure and are easily deformed in the axial force direction. When the axial force sensor assembly 10 is subjected to an axial force, the first connector 240 and the second connector 250 deform identically and the inner mount 22 moves relative to the outer mount 21.

FIGS. 7 and 8 show the bending moment M about the Y direction experienced by a different axial force sensor assembly_YSchematically, the two axial force sensor assemblies have different heights H1, H2 between the first diaphragm 24 and the second diaphragm 25. As can be seen from the figure, the axial force sensor assembly is subjected to a bending moment M_YIn time, since stretching and compression occur in the first and

second films

24 and 25, the change in shape and length is very small. As shown in fig. 7 and 8, the first link 240 of the left portion of the inner mount 22 and the second link 250 of the right portion of the inner mount 22 are compressively deformed, and the first link 240 of the right portion of the inner mount 22 and the second link 250 of the left portion of the inner mount 22 are tensilely deformed. However, since the structure of the first diaphragm 24 and the second diaphragm 25 is rigid when it is pulled and pressed, it is difficult to deform in the radial direction, or the amount of deformation generated is small. Therefore, the total relative displacement between the inner mounting portion 22 and the outer mounting portion 21 is small, that is, the multi-layer connecting member 23 of the present application can suppress the bending moment M about the radial direction_YThe resulting disturbance. In contrast, when the diaphragm having a single-layer structure is subjected to such a bending moment, the diaphragm is a bending arm and is bent and deformed, and thus disturbance caused by the bending moment cannot be effectively suppressed.

In some embodiments, the distance between the first and

second diaphragms

24, 25 in the axial force direction is greater than the diameter D of the inner mount 22, for example, may be greater than or equal to 6 times the diameter D of the inner mount 22. Of course, it will be understood by those skilled in the art that the distance between the first diaphragm 24 and the second diaphragm 25 in the axial force direction may be other multiples than the inner mount diameter. As shown in fig. 7 and 8, a larger distance between the first diaphragm 24 and the second diaphragm 25 in the axial force direction can better resist the torque load, and the larger the distance, the smaller the displacement of the inner mount 22 in the axial force direction, i.e., the multilayer link 23 converts the torque into tensile and compressive behavior of the first diaphragm 24 and the second diaphragm 25, rather than bending behavior. In an extreme embodiment, the distance between the first diaphragm and the second diaphragm in the axial force direction is 10 times the diameter of the inner mounting portion, and the external bending moment is almost entirely converted into tension and compression of the first diaphragm and the second diaphragm, so that the axial force sensor assembly 10 can very effectively suppress the disturbance caused by the bending moment in this case.

Furthermore, due to the radially extending structure of the first diaphragm 24 and the second diaphragm 25, they are rigid when in tension and compression. As shown in FIG. 9, when the axial force sensor assembly 10 is subjected to a shear force F in the radial direction_XThe structure of the multi-layer connection 23 is hardly affected by shear forces, i.e. it is shown that the axial force sensor assembly 10 can suppress radial shear forces very effectively. In the embodiment shown in fig. 3, the first diaphragm 24 and the second diaphragm 25 each have four connecting members. In other embodiments, a different number of links may be present, for example, the greater the number of links, the better the resistance to shear forces in the radial direction.

FIG. 10 illustrates an axial force sensor assembly 10 according to one embodiment of the present application when subjected to a torque M about the axial force direction, i.e., the Z-direction_ZViewed from a top or bottom perspective. Since the multi-layer joint 23 is rigid in the radial direction, i.e., in the X-Y plane, the torque M can be suppressed_Z. The pair of torques M can be further enhanced by increasing the width to length ratio of the first link 240 and the second link 250_ZThe inhibition of (2). In addition, the torque M may be increased by adjusting the thickness, length, and width of the first and

second connection members

240 and 250_ZWhile not affecting the behavior of axial forces and bending moments.

The first sensor 30 detects the relative displacement between the inner mounting part 22 and the outer mounting part 21 of the multilayer link 23 in the axial force direction. In the embodiment shown in fig. 2 and 4, the first sensor 30 comprises a signal transmitter 300 and a signal receiver 301. The signal transmitter 300 and/or the signal receiver 301 may be, for example, inductive, capacitive, resistive, optical, or may use other signal means. In one embodiment, the signal transmitter 300 may be a magnet and the signal receiver 301 may accordingly be a hall effect sensor. When the inner and outer mounting

portions

22, 21 of the multi-layered connector 23 are relatively displaced in the axial force direction, the first sensor 30 senses a change in the magnetic field strength, and thus the relative displacement can be calculated therefrom. In one embodiment, a second sensor 31 is also included, and the second sensor 31 may be of the same type as the first sensor 30, but configured to have an opposite signal trend when relative displacement occurs with respect to the first sensor 30. Based on the configuration of the two sensors having opposite signal trends, and by means of a differential method, the axial force exerted on the axial force sensor assembly 10 can be more accurately calculated from the signals of the first and second sensors. The differential approach can further suppress the effects of other non-axial forces as well as ambient temperature. For a specific application of the differential method, reference may be made to a previous patent application by the applicant (U.S. patent application publication No. 2020/0001472 a), the disclosure of which is hereby incorporated by reference into the present application.

In one embodiment, the transmitter 300 and the receiver 301 are stationary relative to the inner mount 22 and the outer mount 21, respectively, i.e. the transmitter 300 and the receiver 301 may follow the inner mount 22 and the outer mount 21, respectively, to enable detection of relative displacement between the inner mount 22 and the outer mount 21. For example, as shown in fig. 4, the transmitter 300 is mounted on a plug 26 inserted into the bottom of the inner mount 22 to achieve relative rest with the inner mount 22, and the transmitter 301 is mounted on a plate 27 secured to the outer mount 21 to achieve a similar purpose. In other embodiments, the transmitter 300 and receiver 301 may be mounted directly to the inner and outer mounting

portions

22 and 21, respectively. It will be appreciated that in other embodiments, the transmitter 300 may be fixedly attached to the outer mounting portion 21 and the receiver 301 fixedly attached to the inner mounting portion 22.

In one embodiment, as shown in FIG. 4, the first sensor 30 is disposed closer to the inner mount 22 than the outer mount 21. For example, the first sensor 30 is disposed below the inner mount 22 without exceeding the boundary of the inner mount 22. The closer the first sensor 30 is to the center of the axial force sensor assembly 10, the better the bending moment is suppressed.

Referring to fig. 1 and 2, in one embodiment, the axial force sensor assembly 10 further includes an upper cover 40 and a lower cover 50, wherein the upper cover 40 includes a space for receiving the mounting bracket 20 and is fixedly connected to the inner mounting portion 22, for example, by screwing, welding, etc. The lower cover 50 is fixedly connected to the outer mounting portion 21, for example, by screwing, welding, or the like. By providing the upper cover 40 and the lower cover 50 fixed to the inner mounting portion 22 and the outer mounting portion 21, respectively, it is possible to detect the axial force directly applied to the upper cover 40 or the lower cover 50.

According to the above description of the embodiments, it can be understood that the present application uses the multilayer connection member as a detection structure, which can effectively detect the relative displacement caused by the axial force, and at the same time, has a good effect of suppressing non-axial loads, such as shear force, bending moment, torque, etc. While the above multi-layer connecting member structure and principle have been described, those skilled in the art will understand that in addition to the two-layer structure in the above embodiments, more layers of membranes may be used, such as a three-layer connecting member structure or a four-layer connecting member structure, which may also achieve even better effect of suppressing non-axial load.

Another aspect of the application provides a robotic gripper comprising a gripping device and the axial force sensor assembly described in any of the above embodiments, wherein the axial force sensor assembly is configured to detect an axial force exerted by the gripping device.

A further aspect of the application provides a robot comprising a robot jaw as described above.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. "optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.

Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as "about", "approximately" and "substantially", are not to be limited to the precise value specified. In at least some cases, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged, such ranges are designated and include all the sub-ranges contained therein unless context or language indicates otherwise.

The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.

Claims

1. An axial force sensor assembly for sensing axial force, comprising:

the mounting frame comprises an inner mounting part, an outer mounting part and a plurality of layers of connecting pieces connected between the inner mounting part and the outer mounting part, wherein the plurality of layers of connecting pieces are more flexible in the axial force direction than in other load directions; and

a first sensor mounted on the mounting bracket and configured to detect relative displacement between the inner mounting portion and the outer mounting portion in the axial force direction.

2. The axial force sensor assembly of claim 1, wherein the multi-layer connection comprises a first diaphragm and a second diaphragm located at different positions in the axial force direction.

3. The axial force sensor assembly of claim 2, wherein a distance between the first diaphragm and the second diaphragm in the axial force direction is greater than or equal to 6 times the inner mount diameter.

4. The axial force transducer assembly of claim 2, wherein the first diaphragm and the second diaphragm are identical in construction and parallel to each other.

5. The axial force sensor assembly of claim 2, wherein said first diaphragm includes a plurality of first connecting members circumferentially distributed about said inner mounting portion, said second diaphragm includes a plurality of second connecting members circumferentially distributed about said inner mounting portion, each of said first connecting members and said second connecting members connecting said inner mounting portion to said outer mounting portion.

6. The axial force sensor assembly of claim 5, wherein at least a portion of the first connector and at least a portion of the second connector are aligned with one another in the axial force direction.

7. The axial force sensor assembly of claim 5, wherein each of the first connector and the second connector has a length substantially greater than a thickness thereof.

8. The axial force sensor assembly of claim 5, wherein each of the first and second connectors has a substantially straight beam structure extending in a radial direction of the axial force sensor assembly.

9. The axial force sensor assembly of claim 1, further comprising a second sensor, the first and second sensors comprising a signal emitter and a signal receiver, respectively, the signal emitter being a magnet and the signal receiver being a hall effect sensor, the first and second sensors being configured to have opposing signal trends when the axial force sensor assembly is subjected to an axial force, respectively.

10. The axial force sensor assembly of claim 1, wherein the first sensor is disposed closer to the inner mounting portion than the outer mounting portion.

11. A robot gripper, comprising a gripping device and an axial force sensor assembly according to any of claims 1-10, the axial force sensor assembly being configured to detect an axial force applied by the gripping device.

12. A robot comprising a robot gripper according to claim 11.