A triaxial force sensor

Abstract

This invention provides a triaxial force sensor, comprising an elastic body and a strain gauge assembly. The elastic body includes connecting cylinders at both ends and a strain force detection area in the middle. The strain force detection area in the middle of the elastic body is configured as a weak connection structure, which includes at least four strain beams. The area enclosed by the strain beams is arranged in a square shape on the projection plane. The strain gauge assembly is attached to each strain beam. This invention can accurately measure forces in three mutually perpendicular directions and has the advantages of simple structure and fast response speed.

Description

Technical Field

[0001] This utility model relates to the field of sensor technology, specifically to a triaxial force sensor, which is applicable to multiple fields such as mechanical measurement, industrial automation control, robot tactile perception, and biomechanical research. Background Technology

[0002] In existing force measurement technologies, to achieve accurate measurement of forces in multiple directions in space, it is usually necessary to use multiple uniaxial force sensors in combination. This approach not only increases the size and cost of the measurement system, but also affects the overall measurement accuracy due to unavoidable errors during the installation and calibration of each sensor. In addition, some existing triaxial force sensors themselves have problems such as complex structure, insufficient sensitivity, and slow response speed, making it difficult to meet the measurement requirements that combine high precision and real-time performance.

[0003] In the pursuit of simplified structures and improved performance, hollow thin-walled cylindrical structures have been widely used in the design of multidimensional force sensors due to their lightweight and high strength. However, this structure undergoes elliptical deformation under stress. Because strain gauges cannot be uniformly arranged circumferentially, the distribution of stress acquisition points is limited, making it difficult to fully reflect the actual stress state and thus exacerbating the sensor's nonlinearity error. Furthermore, thin-walled structures require high processing precision; even slight concentricity errors can lead to uneven stress distribution, increasing nonlinearity and further affecting the sensor's measurement accuracy and stability. Utility Model Content

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a triaxial force sensor. This invention can accurately measure forces in three mutually perpendicular directions and has the advantages of simple structure and fast response speed.

[0005] This utility model provides a triaxial force sensor, including an elastic body and a strain gauge assembly. The elastic body includes connecting cylinders at both ends and a strain force detection area in the middle. The strain force detection area in the middle of the elastic body is configured as a weak connection structure. The weak connection structure includes at least four strain beams. The area enclosed by the strain beams is arranged in a square shape on the projection plane. The strain gauge assembly is attached to each strain beam.

[0006] In one embodiment, at least four sets of arc-shaped protrusions are provided on the end faces of the connecting cylinders at both ends of the elastic body, and are arranged at equal intervals along the circumferential direction of the connecting cylinders.

[0007] In one embodiment, the arc-shaped boss has a threaded hole that extends deep into the interior of the cylinder for sensor installation and connection.

[0008] In one embodiment, the number of threaded holes is 4, 6, 8 or 10, and they are symmetrically distributed around the center circumference of the connecting cylinder.

[0009] In one embodiment, the strain beam is located at the midline of the line connecting the centers of two adjacent threaded holes.

[0010] In one embodiment, a central positioning groove is provided at the center of the end face of the connecting cylinders at both ends of the elastic body, wherein an adhesive sealing hole is provided at the bottom center of the central positioning groove of the upper connecting cylinder, and a circumferential positioning hole is provided on the upper connecting cylinder of the elastic body.

[0011] In one embodiment, the number of strain beams is set to 4, 6, or 8.

[0012] In one embodiment, at least two of the strain beams are fitted with Z-axis linear compensation plates.

[0013] In one embodiment, the planar profile of a single strain beam on the projection plane is set as a square structure.

[0014] In one embodiment, the ratio of the width to the height of each strain beam is 1:2 to 1:5.

[0015] The beneficial effects of the triaxial force sensor provided by this utility model are as follows:

[0016] This invention utilizes a multi-column beam design for a triaxial force sensor, resulting in a compact structure that significantly improves the sensor's response frequency. Furthermore, the shared strain beam across the X, Y, and Z axes greatly simplifies the structure. By analyzing the strain beams to obtain measured data for each beam, and through strain analysis of the strain gauges to compensate for off-center loads, the sensor's resistance to off-center loads is effectively improved. Simultaneously, a Z-axis linear compensation plate provides linear compensation for the Z-axis load output, effectively enhancing the sensor's linearity in the Z-axis direction.

[0017] Compared to traditional hollow thin-walled cylindrical structures, although strain is generated throughout the entire circumference under external force, the strain distribution in the thin-walled area is often uneven due to manufacturing errors and deviations in the strain gauge mounting position. This unevenness is particularly pronounced under lateral loads, affecting measurement accuracy. This invention employs a beam structure, ensuring that external loads are primarily transmitted through the strain beam, thus concentrating the strain on the beam itself and improving the strain gauge's sensing accuracy.

[0018] Especially under conditions of eccentric or lateral loading, although the stress values ​​of each strain beam may differ, the presence of strain gauges on each beam allows for the separate acquisition of positive and negative strain signals. These signals are then compensated for by a bridge structure, reducing output errors caused by uneven stress distribution. In contrast, traditional hollow cylinder structures, where strain gauges only cover a localized area around the circumference, struggle to fully reflect the overall strain state, resulting in insufficient compensation and larger measurement errors. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A front view of a triaxial force sensor provided in an embodiment of this utility model;

[0021] Figure 2 A top view of the triaxial force sensor provided in an embodiment of this utility model;

[0022] Figure 3 A cross-sectional view of the triaxial force sensor provided in an embodiment of this utility model.

[0023] Reference numerals: 1-elastic body; 2-Z-direction linear compensation plate; 3-threaded hole; 4-central positioning groove; 5-first strain gauge; 6-second strain gauge; 7-adhesive sealing hole; 8-circumferential positioning hole; 9-arc-shaped boss; 10-strain beam; 11-connecting cylinder. Detailed Implementation

[0024] To enable those skilled in the art to better understand the technical solution of this utility model, the preferred embodiments of this utility model are described below in conjunction with specific examples. However, it should be understood that the accompanying drawings are for illustrative purposes only and should not be construed as limiting the present utility model. For better illustration of this embodiment, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable that some well-known structures and their descriptions may be omitted in the drawings for those skilled in the art. The positional relationships described in the drawings are for illustrative purposes only and should not be construed as limiting the present utility model.

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0026] like Figures 1 to 3As shown, a triaxial force sensor includes an elastic body 1 and a strain gauge assembly. The elastic body 1 includes connecting cylinders 11 at both ends and a strain force detection area in the middle. The strain force detection area in the middle of the elastic body 1 is configured as a weak connection structure. The weak connection structure includes at least four strain beams 10. The area enclosed by the strain beams 10 is arranged in a square shape on the projection plane. The strain gauge assembly is attached to each strain beam 10.

[0027] The weak connection structure forms the strain detection zone of the sensor. Its main function is to generate measurable minute deformations under stress, thereby achieving a sensitive response to applied loads. The weak connection structure consists of multiple strain beams 10, and the area enclosed by the multiple strain beams 10 is arranged in a square shape on the projection plane. This area has relatively low local stiffness, i.e., the "weak zone". Under the action of external forces, this area is more prone to elastic deformation than other parts of the elastic body 1, enabling the strain gauge to capture minute deformations and convert them into electrical signals.

[0028] The strain gauge group includes a first strain gauge 5 and a second strain gauge 6. The first strain gauge 5 can sense the force in the X direction on the corresponding strain beam 10, and the second strain gauge 6 can sense the force in the Y direction on the corresponding strain beam 10. Each strain gauge group is equipped with multiple first strain gauges 5 and second strain gauges 6. Each strain beam 10 has first strain gauges 5 and second strain gauges 6 attached to all four sides, and the first strain gauges 5 and second strain gauges 6 are centrally arranged on the side of the strain beam 10.

[0029] In theory, a larger contact area tends to generate greater friction, thus affecting the accurate transmission of force. A smaller contact area, on the other hand, facilitates purer force transmission. A smaller contact surface effectively reduces additional forces caused by uneven contact, such as bending moments or torques, thereby avoiding interference with the measurement results of the main transmitted force. Furthermore, during manufacturing, a smaller contact surface makes it easier to control dimensional consistency and flatness, contributing to improved machining accuracy. Higher flatness reduces installation errors, further decreasing lateral forces generated during testing, thereby enhancing the accuracy and stability of the measurement.

[0030] Therefore, this invention provides at least four sets of arc-shaped protrusions 9 on the end faces of the connecting cylinders 11 at both ends of the elastic body 1, and these protrusions are arranged at equal intervals along the circumferential direction of the connecting cylinders 11. The surface of the arc-shaped protrusions 9 contacts the external equipment, thus reducing the contact area compared to the contact area between the end faces of the connecting cylinders 11 and the external equipment.

[0031] The arc-shaped boss 9 has a threaded hole 3, which extends into the interior of the cylinder 11 for the installation and connection of the sensor.

[0032] The number of threaded holes 3 is 4, 6, 8, or 10, and they are symmetrically distributed around the central circumference of the connecting cylinder 11. In this embodiment, there are 8 threaded holes 3, with 2 threaded holes 3 on each group of arc-shaped bosses 9.

[0033] The strain beam 10 is located at the midline of the line connecting the centers of two adjacent threaded holes 3.

[0034] The end faces of the connecting cylinders 11 at both ends of the elastic body 1 are provided with a central positioning groove 4. The bottom center of the central positioning groove 4 of the upper connecting cylinder 11 is provided with an adhesive sealing hole 7. The connecting cylinder 11 at the upper part of the elastic body 1 is provided with a circumferential positioning hole 8.

[0035] The number of strain beams 10 is set to 4, 6, or 8. During actual testing, in addition to the forces in the X, Y, and Z directions, the strain beams 10 may also be subjected to torsional loads caused by external loads. To improve the resistance of the strain beams 10 to torque, they should be positioned as close as possible to the periphery of the elastic body 1. Since the torsional stiffness of a structure is related to its cross-sectional radius, the larger the diameter of the overall structure, the stronger its resistance to torque disturbances, which helps improve the stability and measurement accuracy of the sensor under complex load environments.

[0036] At least two strain beams 10 are fitted with Z-axis linear compensation plates. In this embodiment, two strain beams 10 are fitted with Z-axis linear compensation plates, which are fitted close to the strain gauge assembly.

[0037] The planar profile of the single strain beam 10 on the projection plane is set as a square structure.

[0038] The ratio of the width to the height of each strain beam 10 is 1:2 to 1:5.

[0039] This invention employs a multi-beam structure design, which effectively concentrates the stress caused by the applied load onto each strain beam, allowing the strain gauges to accurately collect stress points and reflect the current strain state. Arranging corresponding strain gauge groups on each strain beam ensures synchronous multi-point measurement, effectively improving signal stability and consistency. Furthermore, attaching strain gauges with the same strain characteristics to multiple beams allows for the elimination of output errors caused by manufacturing defects and off-center loading between different beams.

[0040] Based on the description and drawings of this utility model, those skilled in the art can easily manufacture or use a triaxial force sensor of this utility model and achieve the positive effects described herein.

[0041] Unless otherwise specified, in this utility model, terms such as "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe orientation or positional relationships in this utility model are for illustrative purposes only and should not be construed as limiting this utility model. For those skilled in the art, the specific meaning of the above terms can be understood in conjunction with the accompanying drawings and according to the specific circumstances.

[0042] Unless otherwise expressly specified and limited, the terms "set up," "connected," and "linked" in this utility model should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0043] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present utility model shall fall within the protection scope of the present utility model.

Claims

1. A triaxial force transducer, characterized by: The device includes an elastomer and a strain gauge assembly. The elastomer includes connecting cylinders at both ends and a strain force detection area in the middle. The strain force detection area in the middle of the elastomer is configured as a weak connection structure. The weak connection structure includes at least four strain beams. The area enclosed by the strain beams is arranged in a square shape on the projection plane. The strain gauge assembly is attached to each strain beam.

2. The triaxial force transducer of claim 1, wherein: At least four sets of arc-shaped protrusions are provided on the end faces of the connecting cylinders at both ends of the elastic body, and are arranged at equal intervals along the circumferential direction of the connecting cylinders.

3. The triaxial force transducer of claim 2, wherein: The arc-shaped boss has a threaded hole that extends deep into the cylinder for sensor installation and connection.

4. The triaxial force transducer of claim 3, wherein: The number of threaded holes is 4, 6, 8 or 10, and they are symmetrically distributed around the center circumference of the connecting cylinder.

5. The triaxial force transducer of claim 3, wherein: The strain beam is located at the midline of the line connecting the centers of two adjacent threaded holes.

6. The triaxial force transducer of claim 1, wherein: The connecting cylinders at both ends of the elastic body are provided with a central positioning groove at the center of their end faces. The center of the bottom of the central positioning groove of the upper connecting cylinder is provided with an adhesive sealing hole. The connecting cylinder at the top of the elastic body is provided with a circumferential positioning hole.

7. The triaxial force transducer of claim 1, wherein: The number of strain beams is set to 4, 6, or 8.

8. The triaxial force transducer of claim 1, wherein: At least two of the strain beams are fitted with Z-axis linear compensation plates.

9. The triaxial force transducer of claim 1, wherein: The planar profile of a single strain beam on the projection plane is set as a square structure.

10. The triaxial force transducer of claim 1, wherein: The ratio of the width to the height of each strain beam is 1:2 to 1:5.

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