GB2614373A

GB2614373A - Force arm structure for multi-dimensional force and torque sensor and multi-dimensional force and torque sensor

Info

Publication number: GB2614373A
Application number: GB2215410.8A
Authority: GB
Inventors: Xu Chengyi; Yang Xuemei; Liu Yongnian; Lei Weiwu
Original assignee: Songnuomeng Tech Co Ltd
Current assignee: Songnuomeng Tech Co Ltd
Priority date: 2022-01-04
Filing date: 2022-10-18
Publication date: 2023-07-05
Also published as: CN114370968A; KR20230105637A; DE102022129794A1; GB202215410D0

Abstract

A force arm structure for multi-dimensional force and torque sensor comprises an outer ring 110, an inner ring 110, and at least two strain beams which are integrally moulded into a circular plate-like structure. The inner ring is located inside the outer ring and is provided coaxially with the outer ring. At least two strain beams are evenly arranged in a circumferential direction of the inner ring at an interval. Each strain beam 130 comprises a primary beam 131 and a secondary beam 132 crossed with each other. The first strain gauge 141 is located on the primary beam. A second strain gauge 142 and a third strain gauge 143 are arranged on the secondary beam at an interval so that they near the two locations where the secondary beam joins the outer ring. The first, second and third strain gauges are located on the same flat surface of the structure or in the same plane. The strain gauges may be manufactured by nano-spluttering.

Description

FORCE ARM STRUCTURE FOR MULTI-DIMENSIONAL FORCE AND TORQUE

SENSOR AND MULTI-DIMENSIONAL FORCE AND TORQUE SENSOR

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of torque sensors, and in particular relates to a force arm structure for multi-dimensional force and torque sensor, and a multi-dimensional force and torque sensor.

BACKGROUND

[0002] As a torque detection device, torque sensors can be used in robot joints, medical devices, military equipment and other applications for real-time detection of force and torque. Especially multi-dimensional force and torque composite sensors, which are mostly used in force control systems of various robots (mechanical arms) or other devices or systems that need to detect force values, are used to measure forces in three directions of X, Y and Z axes and torques around X, Y and Z axes. In the commonly used technologies, strain gauges need to be arranged on a plurality of different faces of the strain beam at same time, and are bonded to the strain beam by means of an organic glue, thus achieving measurement of force values or torques of different dimensions. During pasting, a plurality of processes needing delicate operation such as precise positioning, surface treatment, compaction and glue drying are needed, and automation is inconvenient to achieve, which greatly reduce the production efficiency of the multi-dimensional force and torque composite sensor.

SUNIMARY

100031 To this end, for the problem that the traditional multi-dimensional force and torque sensor is low in machining efficiency, it is necessary to provide a force arm structure for multi-dimensional force and torque sensor and a multi-dimensional force and torque sensor which are high in machining efficiency.

[0004] A force arm structure for multi-dimensional force and torque sensor comprises an outer ring, an annular inner ring, and at least two strain beams.

100051 The inner ring is located inside the outer ring and is provided coaxially with the outer ring; [0006] The at least two strain beams are evenly arranged in a circumferential direction of the inner ring at an interval. Each strain beam comprises a primary beam and a secondary beam which are crossed with each other. The two ends of the secondary beam are connected to an inner wall of the outer ring, and the two ends of the primary beam are respectively connected to a middle portion of the secondary beam and an outer wall of the inner ring [0007] A first strain gauge is arranged on the primary beam; a second strain gauge and a third strain gauge are arranged on the secondary beam at an interval; and the first strain gauge and the second strain gauge are respectively located at either side of the primary beam.

100081 The first strain gauge, the second strain gauge and the third strain gauge are located on a same side of the inner ring.

[0009] In some of the embodiments, the first strain gauge, the second strain gauge and the third strain gauge are located in a same plane.

100101 In some of the embodiments, the outer ring, the inner ring, the primary beam and the secondary beam form an integrally molding structure.

100111 The outer ring has a first surface on a same side as the first strain gauge, the inner ring has a second surface on the same side as the first strain gauge, a side face, provided with the first strain gauge, of the primary beam, a side face, provided with the second strain gauge, of the secondary beam, the first surface and the second surface are flush with one another.

[0012] In some of the embodiments, each primary beam is perpendicular to the secondary beam connected thereto; and/or 100131 a flexural gap is formed between a side surface, away from the inner ring, of the secondary beam and the inner wall of the outer ring.

[0014] In some of the embodiments, the outer ring and the inner ring are both of a plate-like structure; and along a central axis direction of the inner ring, a size of the primary beam and a size of the secondary beam are smaller than both a size of the outer ring and a size of the inner ring.

100151 In some of the embodiments, a surface of the primary beam at a side away from the first strain gauge is a first face, and an inward-recessed first groove is arranged on the first face at a position where the first face aligns with the first strain gauge [0016] A side surface, towards the outer ring, of the secondary beam and a side surface, away from the outer ring, of the secondary beam are respectively defined as a second face and a third face; inward-recessed second grooves are arranged on the second face at positions where the second face aligns with the second strain gauge and the third strain gauge respectively; and inward-recessed third grooves are arranged on the third face at positions where the third face aligns with the second strain gauge and the third strain gauge respectively.

[0017] In some of the embodiments, the inner ring is of a circular annular plate-like structure, and an extending direction of the primary beam is consistent with a diameter direction of the inner ring.

[0018] In some of the embodiments, the first strain gauge, the second strain gauge and the third strain gauge are electrically connected to a control chip in the multi-dimensional force and torque sensor through a flip process.

[0019] In some of the embodiments, the first strain gauge is a nano-film strain resistor formed on the primary beam through a film sputtering deposition technology; and the second strain gauge and the third strain gauge are both nano-film strain resistors formed on the secondary beam through a film sputtering deposition technology; and/or [0020] The strain beams are made of martensitic precipitation stainless steel.

[0021] A multi-dimensional force and torque sensor, comprising the force arm structure for multi-dimensional force and torque sensor as described above [0022] In accordance with the force arm structure for multi-dimensional force and torque sensor and the multi-dimensional force and torque sensor above, due to the fact that the first strain gauge, the second strain gauge and the third strain gauge used for respectively measuring force values or torques of different dimensions are located on the same side of the inner ring, the fabrication of all strain gauges can be completed at one time on the strain beam in the machining process of the multi-dimensional force and torque sensor, which is conducive to the improvement of the machining efficiency of the multi-dimensional force and torque sensor. Further, the first strain gauge, the second strain gauge and the third strain gauge are all provided at positions with large machining spaces, such that the fabrication of the strain gauge is easier and more convenient, and the machining efficiency of the multi-dimensional force and torque sensor is further improved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a structure diagram of a force arm structure for multi-dimensional force and torque sensor in an embodiment of the present disclosure; [0024] FIG. 2 is a structure diagram of a force arm structure for multi-dimensional force and torque sensor in another embodiment of the present disclosure; [0025] FIG. 3 is a rear view of the force arm structure for multi-dimensional force and torque sensor shown in FIG. 1; [0026] FIG. 4 is a sectional view of A-A of the force arm structure for multi-dimensional force and torque sensor shown in FIG. 3; 100271 FIG. 5 is a partial sectional view of B-B of the force arm structure for multi-dimensional force and torque sensor shown in FIG. 3; 100281 FIG. 6 is a partial sectional view of C-C of the force arm structure for multi-dimensional force and torque sensor shown in FIG. 3.

[0029] In the drawings: 100-force arm structure for multi-dimensional force and torque sensor; 110-outer ring; 120-inner ring; 130-strain beam; 131-primary beam; 1311-first face; 1312-first groove; 132-secondary beam; 1321-second face; 1322-third face; 1323-second groove; 1324-third groove; 141-first strain gauge; 142-second strain gauge; 143-third strain gauge; 150-flexural gap.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] In order to facilitate the understanding of the present disclosure, the present disclosure will be described in details below with reference to the related drawings. Preferred embodiments of the present disclosure are shown in the accompanying drawings. However, the present disclosure can be embodied in many different forms and is not limited to the embodiments described herein. Rather, the purpose of providing these embodiments is to provide a thorough understanding of the present disclosure.

100311 Unless otherwise defined, all the technical and scientific terms used herein have the same meanings generally understood by those skilled in the art of the present disclosure. Herein, the terms used in the specification of the present disclosure are intended to describe specific embodiments, instead of limiting the present disclosure. The term "and/or" used herein includes any combination and all combinations of one or more related items listed.

[0032] In the description of a positional relationship, unless otherwise specified, when an element is referred to as being "on" another element, it can be directly on other element or intervening elements may also be present. It may also be understood that when an element is referred to as being "between" two elements, it can be the only one between the two elements, or one or more intervening elements may also be present.

[0033] In a case where -comprise-, -have-, and -include-described herein are used, another component may also be added unless explicit qualifiers such as "only," "consisting of," and like are used. Unless indicated to the contrary, terms in the singular form may include the plural form and are not to be understood as having a number of one.

[0034] In addition, the drawings are not drawn at a 1:1 scale, and the relative dimensions of the elements are drawn in the drawings only in an exemplary manner and not necessarily to the true scale, 100351 As described in the background, in the traditional multi-dimensional force and torque sensor, in order to measure force values or torques of different dimensions, it is necessary to manufacture the corresponding strain gauges on different surfaces of the strain beam, and therefore the strain gauges need to be manufactured for multiple times in the machining process of the multi-dimensional force and torque sensor. In consideration of the strain beam and the force arm structure of the torque sensor, some strain gauges are likely to be arranged at narrow positions, which not only increases the fabrication difficulty of the strain gauges, but also affects the fabrication speed of the strain gauges, leading to the low machining efficiency of the traditional multi-dimensional force and torque sensor.

[0036] Based on the reasons above, a multi-dimensional force and torque sensor moment arm structure and a multi-dimensional force and torque sensor are disclosed. The multi-dimensional force and torque sensor comprises a multi-dimensional force and torque moment arm structure. [0037] FIG. 1 and FIG. 2 respectively illustrate structure diagrams of a force arm structure for multi-dimensional force and torque sensor in accordance with an embodiment I and an embodiment II of the present disclosure. To ease the description, the drawings only illustrate structures related to the embodiments of the present disclosure.

100381 Referring to FIG.1 and FIG. 2, in a preferred embodiment of the present disclosure, the force arm structure for multi-dimensional force and torque sensor 100 comprises an outer ring 110, an annular inner ring 120, and at least two strain beams 130.

100391 The inner ring 120 is located inside the outer ring 110, and is provided coaxially with the outer ring 110. Specifically, the outer ring 110 and the inner ring 120 are concentrically provided. The structure of the outer ring 110 may be the same as, or different from, that of the inner ring 120, and the structure may be a plate-like or cylindrical structure having the same inner wall shape and outer wall shape, or a plate-like or cylindrical structure having different inner wall shape and outer wall shape.

100401 At least two strain beams 130 are evenly provided in a circumferential direction of the inner ring 120 at an interval. Each strain beam 130 comprises a primary beam 131 and a secondary beam 132 which are crossed with each other. A sectional shape of the primary beam 131 perpendicular to a longitudinal direction and a sectional shape of the secondary beam 132 perpendicular to the longitudinal direction may be rectangle, trapezoid, an irregular shape with side lines formed by curves, a T shape, a U shape and the like.

[0041] Two ends of the secondary beam 132 are connected to the inner wall of the outer ring 110. The two ends of the primary beam 131 are respectively connected to a middle portion of the secondary beam 132 and the outer wall of the inner ring 120. Therefore, the outer ring 110 is fixedly connected to the inner ring 120 through the strain beam 130. The primary beam 131, the secondary beam 132, the outer ring 110 and the inner ring 120 may be fixedly connected by means of welding, screwing, riveting and the like, or may be integrally molded by means of machining, casting and the like. In the actual application of the multi-dimensional force and torque sensor, after a rotational load is input to the outer ring 110 or the inner ring 120, the outer ring 110 and the inner ring 120 tend to rotate relative to each other to drive the primary beam 131 and the secondary beam 132 to strain.

100421 It needs to be noted that in each strain beam 130, the primary beam 131 and the secondary beam 132 are crossed with each other. That is, the primary beam 131 and the secondary beam 132 are perpendicular to each other, or there is an included angle of less than 90 degrees between the primary beam 131 and the secondary beam 132.

100431 Specifically, the strain beam 130 is made of martensitic precipitation stainless steel so as to improve the fatigue and corrosion resistance of the strain beam 130. The service life of the strain beam 130 is effectively prolonged, and thus the service life of the multi-dimensional force and torque sensor is further prolonged.

[0044] Each primary beam 131 is provided with a first strain gauge 141, and each secondary beam 132 is provided with a second strain gauge 142 and a third strain gauge 143 at an interval. In each strain beam 130, the first strain gauge 141 and the second strain gauge 142 are respectively located at either side of the primary beam 131. The first strain gauge 141 is configured to detect first strain information of a corresponding position on the primary beam 131, and the second strain gauge 142 and the third strain gauge 143 are configured to respectively detect second strain information and third strain information at corresponding positions of the secondary beam 132. In the multi-dimensional force and torque sensor, torque values or force values of different dimensions of a to-be-detected piece are obtained through the first strain information, the second strain information and the third strain information. For example, through the first strain information, the second strain information and the third strain information, the force values on the X axis, the Y axis and the Z axis are respectively acquired, or the torque values of the X axis, the Y axis and the Z axis are respectively acquired.

100451 Specifically, each primary beam 131 is perpendicular to the secondary beam 132 connected thereto, it is guaranteed that the first strain gauge 141, the second strain gauge 142 and the third strain gauge 143 can simultaneously measure the force values in an X direction, a Y direction and a Z direction which are perpendicular to one another, respectively, or simultaneously measure the torque values around the X axis, the Y axis and the Z axis, respectively, thus facilitating subsequent measurement work of the multi-dimensional force and torque sensor and improving the measurement accuracy.

[0046] Specifically, a flexural gap 150 is formed between a side surface, away from the inner ring 120, of the secondary beam 132 and the inner wall of the outer ring 110. Through the arrangement of the flexural gap 150, the secondary beam 132 is more prone to strain deformation, the measurement of the subsequent torque value or torsion is easier and more sensitive, and the measurement sensitivity and the measurement accuracy of the multi-dimensional force and torque sensor are improved.

100471 The first strain gauge 141, the second strain gauge 142 and the third strain gauge 143 are located on the same side of the inner ring 120. That is, the first strain gauge 141, the second strain gauge 142 and the third strain gauge 143 are located on the same side of the strain beam 130, such that the first strain gauge 141, the second strain gauge 142 and the third strain gauge 143 have the same orientation. Specifically, the first strain gauge 141, the second strain gauge 142 and the third strain gauge 143 are perpendicular to the central axis of the inner ring 120.

[0048] In the multi-dimensional force and torque sensor, due to the fact that the first strain gauge 141, the second strain gauge 142 and the third strain gauge 143 for measuring strain information of different dimensions are located on the same side of the strain beam 130, the fabrication of all strain gauges can be completed at one time on the strain beam 130. Compared with the situation that in the machining of the traditional multi-dimensional force and torque sensor, where the strain gauges need to be fabricated for multiple times on different surfaces of the strain beam 130, the fabrication time of the strain gauges can be greatly shortened through the above way of fabricating all strain gauges at one time, and therefore, the machining efficiency of the multi-dimensional force and torque sensor can be effectively improved.

[0049] Further, as the first strain gauge 141, the second strain gauge 142 and the third strain gauge 143 are located on the same side of the inner ring 120, the spaces around the positions where the first strain gauge 141, the second strain gauge 142 and the third strain gauge 143 are located are relatively big, and the fabrication of each strain gauge on the strain beam 130 is easier and more convenient, and the machining efficiency of the multi-dimensional force and torque sensor can be effectively improved.

100501 In some embodiments, the first strain gauge 141, the second strain gauge 142 and the third strain gauge 143 are located in the same plane. Therefore, a side face, provided with the first strain gauge 141, of the primary beam 131 is flush with a side surface, provided with the second strain gauge 142 and the third strain gauge 143, of the secondary beam 132. The fabrication quality of all strain gauges may be guaranteed in the one-time fabrication process of all strain gauges, such that the multi-dimensional force and torque sensor has both high machining quality and product quality.

100511 Furthermore, in some embodiments, the outer ring 110, the inner ring 120, the primary beam 131 and the secondary beam 132 form an integrally molding structure. The outer ring 110 has a first surface on the same side as the first strain gauge 141. The inner ring 120 has a second surface on the same side as the first strain gauge 141. A side surface, provided with the first strain gauge 141, of the primary beam 131, a side surface, provided with the second strain gauge 142, of the secondary beam 132, the first surface and the second surface are flush with one another.

[0052] The outer ring 110, the inner ring 120, the primary beam 131 and the secondary beam 132 are integrally molded, which not only makes the connection between the primary beam 131 and the secondary beam 132, the connection between the primary beam 131 and the inner ring 120 and the connection between the secondary beam 132 and the outer ring 110 firmer, but also improves the structure stability of the force arm structure for multi-dimensional force and torque sensor 100, and thus the multi-dimensional force and torque sensor has longer service life and higher use reliability. Further, due to the fact that a side surface, provided with the first strain gauge 141, of the primary beam 131, a side surface, provided with the second strain gauge 142, of the secondary beam 132, the first surface and the second surface are flush with one another, during machining, the machining of the force arm structure for multi-dimensional force and torque sensor 100 may also be simplified while guaranteeing that the first strain gauge 141, the second strain gauge 142 and the third stain gauge 143 are located in the same plane, and it is conducive to further improving the machining efficiency of the multi-dimensional force and torque sensor.

[0053] Referring to FIG. 3 and FIG. 4, in some embodiments, the outer ring 100 and the inner ring 120 are both of a plate-like structure. In a central axis direction of the inner ring 120, the size of the primary beam 131 and the size of the secondary beam 132 are smaller than both the size of the outer ring 110 and the size of the inner ring 120. Therefore, the thickness of the strain beam 130 is less than both the thickness of the outer ring 110 and the thickness of the inner ring 120. Compared with the outer ring 110 and the inner ring 120, the primary beam 131 and the secondary beam 132 are more prone to strain generation, which is conducive to improving the sensitivity of the multi-dimensional force and torque sensor.

[0054] Referring to FIG. 3 to FIG. 6, in some embodiments, the surface of the primary beam 131 at a saide away from the first strain gauge 141 is a first face 1311. an inward-recessed first groove 1312 is arranged on the first face 1311 at a position where the first face aligns with the first strain gauge 141. The side surface, towards the outer ring 110, of the secondary beam H2 and the side surface, away from the outer ring 110, of the secondary beam 132 are respectively defined as a second face 1321 and a third face 1322. Inward-recessed second grooves 1323 are arranged on the second face 1321 at positions where the second face 1321 aligns with the strain gauge 142 and the third strain 143 respectively.Inward-recessed third grooves 1324 are arranged on the third face 1322 at positions where the third face 1322 aligns with the second strain gauge 142 and the third strain gauge 143 respectively. Specifically, the second grooves 1323 and the third grooves 1324 are both located on the surface of a side of the secondary beam 132 away from the second strain gauge 142, thus simplifying the machining of the secondary beam 132.

100551 The providing of the first groove 1312 may reduce the axial size of the primary beam 131 at the position where the first strain gauge 141 is provided on the primary beam 131, while the providing of the second grooves 1323 and the third grooves 1324 may reduce the size of the secondary beam 132 at the positions where the second strain gauge 142 and the third strain gauge 143 is provided on the secondary beam 132 in a direction pointing to the inner ring 120 from the outer ring 110, thereby guaranteeing that the position on the primary beam 131 where the first strain gauge 141 is provided is more prone to strain generation in a first direction, the two ends of the secondary beam 132 are subjected to strain in a second direction and a third direction perpendicular to the first direction, and the sensitivity of the multi-dimensional force and torque sensor is improved.

100561 In the embodiments above, it needs to be noted that the axial size of the primary beam 131 refer to the thickness of the primary beam 131 in a central axis direction of the inner ring 120, while the size of the secondary beam 132 in a direction pointing to the inner ring 120 from the outer ring 110 refers to the size of the secondary beam 132 in a direction perpendicular to the central axis of the inner ring 120.

100571 Specifically, the first groove 1312, the second groove 1323 and the third groove 1324 each are a rectangular groove or a trapezoid groove. In a longitudinal direction of the secondary beam 132, the thickness of the bottom wall of the second groove 1323 and the thickness of the bottom wall of the third groove 1324 are both gradually reduced along a direction pointing to the primary beam 131. In a longitudinal direction of the primary beam, the thickness of the bottom wall of the first groove 1312 is gradually reduced in a direction pointing to the secondary beam 132. In accordance with such arrangement, the primary beam 131 is more prone to strain in a first direction at a position where the first groove 1312 is formed, the secondary beam 132 is more prone to strain at the positions where the second groove 1323 and the third groove 1324 are formed, thus the first strain gauge 141, the second strain gauge 142 and the third strain gauge 143 are more prone to detecting strain information, and the measurement sensitivity of a multi-dimensional force and torque sensor is further improved.

[0058] In some embodiments, the inner ring 120 is of a circular annular plate-like structure. An extending direction of the primary beam 131 is consistent with a diameter direction of the inner ring 120. Therefore, the primary beam 131 extends in the diameter direction of the inner ring 120 to guarantee that the primary beam 131 may generates strain timely and accurately when the outer ring 110 and the inner ring 120 are in relative rotation, thereby improving the measurement sensitivity and the measurement accuracy of the multi-dimensional force and torque sensor.

100591 In some embodiments, the first strain gauge 141, the second strain gauge 142 and the third strain gauge 143 are all electrically connected to a control chip in the multi-dimensional force and torque sensor through a flip process. Where the flip process refers to a relatively mature flip process in the chip packaging industry, and by adopting the flip process, the first strain gauge 141, the second strain gauge 142 and the third strain gauge 143 can be electrically connected to a control chip and the like without welding or connecting a large number of leads, such that the operation is easier, the automation is easier to realize, the cost is reduced, and the machining efficiency of the multi-dimensional force and torque sensor can be further improved. 100601 In some embodiments, the first strain gauge 141 is a nano-film strain resistor formed on the primary beam 131 by a film sputtering deposition technology The second strain gauge 142 and the third strain gauge 143 are both nano-film strain resistors formed on the secondary beam 132 by a film sputtering deposition technology. Therefore, through the film sputtering deposition technology, the binding force between the first strain gauge 141 and the primary beam 131 is greatly improved, and the binding force between the second strain gauge 142 as well as the third strain gauge and the secondary beam 132 is also increased, the possibility that the strain gauges detach from the strain beam 130 is reduced, and the service life of the multi-dimensional force and torque sensor is effectively prolonged. Moreover, the use of the film sputtering deposition technology above can enable the multi-dimensional force and torque sensor to have the advantages of low temperature coefficient, no creep, small lag, better overall precision and suitability for a higher-temperature working environment.

100611 The technical features of above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for simplicity of description. However as long as the combinations of technical features do not contradict each other, the technical features should be considered to be within scope of description of present specification.

100621 The above embodiments represent only several embodiments of the present disclosure, and the description thereof is specific and detailed, but should not therefore be construed as limiting the scope of the present disclosure. It should be noted that for those of ordinary skill in the art, several variations and modifications can be made without departing from the concept of the present disclosure, all of which fall within the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure shall be subject to the appended claims.

Claims

WHAT IS CLAIMED IS: 1. A force arm structure for multi-dimensional force and torque sensor, comprising an outer ring, an annular inner ring, and at least two strain beams; the inner ring is located inside the outer ring and is provided coaxially with the outer ring; the at least two strain beams are evenly arranged in a circumferential direction of the inner ring at an interval, each strain beam comprises a primary beam and a secondary beam which are crossed with each other; two ends of the secondary beam are connected to an inner wall of the outer ring; two ends of the primary beam are respectively connected to a middle portion of the secondary beam and an outer wall of the inner ring.a first strain gauge is arranged on the primary beam; a second strain gauge and a third strain gauge are arranged on the secondary beam at an interval; the first strain gauge and the second strain gauge are respectively located at either side of the primary beam; wherein the first strain gauge, the second strain gauge and the third strain gauge are located on a same side of the inner ring 2. The force arm structure for multi-dimensional force and torque sensor according to claim 1, wherein the first strain gauge, the second strain gauge and the third strain gauge are located in a same plane.3. The force arm structure for multi-dimensional force and torque sensor according to claim 2, wherein the outer ring, the inner ring, the primary beam and the secondary beam form an integrally molding structure; the outer ring has a first surface on a same side as the first strain gauge, the inner ring has a second surface on the same side as the first strain gauge; a side face, provided with the first strain gauge, of the primary beam, a side face, provided with the second strain gauge, of the secondary beam, the first surface and the second surface are flush with one another.4. The force arm structure for multi-dimensional force and torque sensor according to claim 1, wherein each primary beam is perpendicular to the secondary beam connected thereto, and/or a flexural gap is formed between a side surface, away from the inner ring, of the secondary beam and the inner wall of the outer ring.5. The force arm structure for multi-dimensional force and torque sensor according to claim 1, wherein the outer ring and the inner ring are both of a plate-like structure; and along a central axis direction of the inner ring, a size of the primary beam and a size of the secondary beam are smaller than both a size of the outer ring and a size of the inner ring.6 The force arm structure for multi-dimensional force and torque sensor according to claim 1, wherein a surface of the primary beam at a side away from the first strain gauge is a first face, and an inward-recessed first groove is arranged on the first face at a position where the first face aligns with the first strain gauge, a side surface, towards the outer ring, of the secondary beam and a side surface, away from the outer ring, of the secondary beam are respectively defined as a second face and a third face; inward-recessed second grooves are arranged on the second face at positions where the second face aligns with the second strain gauge and the third strain gauge respectively; and inward-recessed third grooves are arranged on the third face at positions where the third face aligns with the second strain gauge and the third strain gauge respectively.7. The force arm structure for multi-dimensional force and torque sensor according to claim 1, wherein the inner ring is of a circular annular plate-like structure, and an extending direction of the primary beam is consistent with a diameter direction of the inner ring.8. The force arm structure for multi-dimensional force and torque sensor according to claim 1, wherein the first strain gauge, the second strain gauge and the third strain gauge are electrically connected to a control chip in the multi-dimensional force and torque sensor through a flip process.9. The force arm structure for multi-dimensional force and torque sensor according to claim 1, wherein the first strain gauge is a nano-film strain resistor formed on the primary beam through a film sputtering deposition technology; the second strain gauge and the third strain gauge are both nano-film strain resistors formed on the secondary beam through a film sputtering deposition technology; and/or the strain beams are made of martensitic precipitation stainless steel.10. A multi-dimensional force and torque sensor, comprising the force arm structure for multi-dimensional force and torque sensor according to any one of claims 1 to 9.