Six-dimensional force sensor

Abstract

This application relates to the field of force sensor technology, and in particular to a six-dimensional force sensor, which includes a first support base, an elastic body, and a second support base, all arranged in a ring shape and spaced apart along a central axis. Multiple first connecting beams connect the first support base and the elastic body, and multiple second connecting beams connect the second support base and the elastic body. The most easily deformable directions of the first and second connecting beams are perpendicular to the most easily deformable direction of the elastic body, and at least two of the most easily deformable directions of the multiple first and second connecting beams are perpendicular to each other. Strain gauges are provided on the most easily deformable surfaces of the elastic body, the first connecting beams, and the second connecting beams. The six-dimensional force sensor has a hollow structure, providing ample space for wiring and accommodating more lines, solving the problem of limited wiring capacity in traditional sensors. It also facilitates orderly arrangement of lines, avoids tangling and interference, and ensures stable signal transmission.

Description

Technical Field

[0001] This application relates to the field of force sensor technology, and in particular to a six-dimensional force sensor. Background Technology

[0002] A six-dimensional force sensor is a high-precision measuring device that can simultaneously measure force and torque in three coordinate directions in space by attaching strain gauges to a beam of an elastic body. Each force corresponds to a vector with magnitude and direction, and its calibration assumes that the sensor system is a linear system.

[0003] Six-dimensional force sensors are typically installed at the end of the actuator unit of humanoid robots or industrial robotic arms, much like a human wrist and ankle. Once installed, they enable effective force control of the robot. They mainly consist of an elastomer, strain gauges, and a circuit board. The elastomer is a circumferential support, a medium used to withstand deformation. The strain gauge is a device used to measure the local deformation of the elastomer, converting the deformation of the elastomer into the strain gauge's deformation. Furthermore, by measuring the ratio of deformation to resistance, the magnitude of the force is determined. The circuit board, also known as a data acquisition board, is a data processing system that converts the measured strain gauge pressure data into digital signals that the machine can understand. Once the main controller receives the digital signals, the machine can determine the weight of the object.

[0004] Existing technologies, such as the invention patent with publication number CN109238529B, disclose a six-dimensional sensor, mainly composed of a circumferential support, a central platform, and radial beams and floating beams on which strain gauges are laid, which can collect deformation information through strain gauges on the radial beams and floating beams. The invention patent with publication number CN118067296B discloses a low-stress six-dimensional force sensor, mainly composed of a shell, a central support platform, and multiple elastic beams located circumferentially on the central support platform and on which strain gauges are laid. The invention patent with publication number CN116164873B discloses a six-dimensional force sensor, the main body of which is mainly composed of a mounting base, a central shaft, and multiple elastic beams located circumferentially on the central shaft and on which strain gauges are laid.

[0005] When applied to humanoid robots and other applications requiring multiple sensors to work together to collect force information from multiple parts of the body, a large number of lines need to be laid out to transmit data and perform integrated processing. The aforementioned six-dimensional sensor structure has a compact internal space, and due to the complexity of line integration, it is prone to entanglement and compression problems, which is not conducive to wiring and laying lines; system maintenance is difficult, and the cost of troubleshooting line faults is high; the space utilization rate is low when multiple sensors are laid out, which affects the overall structural design of the robotic arm. Utility Model Content

[0006] To address the problem that the compact internal space of a six-dimensional sensor structure leads to complex circuit integration, which can cause tangling and compression, making it difficult to lay wiring, this application provides a six-dimensional force sensor.

[0007] The six-dimensional force sensor provided in this application adopts the following technical solution:

[0008] A six-dimensional force sensor includes a first support base, an elastic body, and a second support base, all arranged in a ring shape and spaced apart along a central axis. A plurality of first connecting beams connect the first support base and the elastic body, and a plurality of second connecting beams connect the second support base and the elastic body.

[0009] The most easily deformable directions of the first connecting beam and the second connecting beam are both perpendicular to the most easily deformable direction of the elastic body, and the most easily deformable directions of the plurality of first connecting beams and the plurality of second connecting beams have at least two perpendicular directions; strain gauges are provided on the most easily deformable surfaces of the elastic body, the first connecting beam and the second connecting beam.

[0010] By adopting the above technical solution, the first support, the elastic body, and the second support are all annular, making the six-dimensional force sensor form a hollow structure as a whole. This provides a larger space for wiring and can accommodate more lines, solving the problem of limited wiring capacity in traditional sensors. At the same time, it facilitates the orderly arrangement of lines, avoids tangling and interference, and ensures stable signal transmission. The most easily deformable directions of the first and second connecting beams are both perpendicular to the most easily deformable direction of the elastic body, and at least two of the most easily deformable directions of the multiple first and second connecting beams are perpendicular to each other. Combined with the placement of strain gauges on the most easily deformable surfaces of each component, structural decoupling is achieved, reducing mutual interference between measurements in different directions, allowing the strain gauges to capture deformation more efficiently, and improving the accuracy, sensitivity, and resolution of load measurements in different directions.

[0011] Optionally, the elastomer is an annular sheet, and the most easily deformable direction of the elastomer is the central axis direction.

[0012] By adopting the above technical solution, the elastomer has low stiffness and high flexibility in the central axis direction. When subjected to force along the Z-axis or torque about an axis perpendicular to the Z-axis, it can mainly induce strain response in the Z-direction, which is suitable for the scenario requirements of high-precision measurement of Z-direction loads. At the same time, the annular sheet structure generates a symmetrical tensile and compressive strain field when subjected to force in the Z-direction, which facilitates the strain gauge to accurately capture strain changes, improve the signal-to-noise ratio of the strain signal, and ensure the sensitivity and accuracy of Z-direction load measurement.

[0013] Optionally, the first connecting beam is sheet-like, and the most easily deformable direction of the first connecting beam is the thickness direction.

[0014] By adopting the above technical solution, when the X / Y forces and Z-axis torques act on the thickness direction of the first connecting beam, the first connecting beam is most likely to undergo bending deformation around the neutral axis in the width direction. The sheet-like structure concentrates the strain on both sides of the first connecting beam. The strain gauges are laid on the most easily deformable plate surface, making it easier to collect the deformation of the first connecting beam and thus change the resistance value. This can effectively improve the resolution of the sensor for measuring the X / Y forces and Z-axis torques.

[0015] Optionally, the width direction of the first connecting beam is perpendicular to the radial direction of the elastic body.

[0016] By adopting the above technical solution, when subjected to X / Y directional forces or moments about the Z-axis, the direction of the force more directly corresponds to the thickness direction (the direction most prone to deformation) of the first connecting beam. This makes the first connecting beam more prone to bending deformation about the neutral axis in the width direction, enhancing its response sensitivity to relevant loads. Simultaneously, this directional arrangement optimizes the force transmission path on the first connecting beam, making the deformation more stable and concentrated, facilitating the accurate capture of strain changes by strain gauges, and improving the accuracy and resolution of corresponding force and moment measurements. The vertically positioned, sheet-like first connecting beam enhances the structural stability and force transmission efficiency. When subjected to vertical forces, it better utilizes its bending characteristics, producing significant deformation, which is beneficial for the overall sensor layout and reduces its size.

[0017] Optionally, four first connecting beams are provided, which are evenly spaced along the circumference of the elastic body.

[0018] By adopting the above technical solution, the load can be evenly distributed on each of the first connecting beams, avoiding structural damage caused by excessive local stress and improving the overall stability and load-bearing capacity of the structure. At the same time, the evenly spaced distribution allows the first connecting beams to produce symmetrical and balanced deformation responses when subjected to forces or moments in different directions, reducing measurement deviations caused by uneven distribution. Combined with strain gauges, the strain changes of each beam can be captured more stably, improving the accuracy and consistency of the corresponding force and moment measurements.

[0019] Optionally, the second connecting beam is sheet-like, and the direction in which the second connecting beam is most easily deformed is the thickness direction.

[0020] By adopting the above technical solution, when subjected to X / Y directional forces or moments around the Z-axis in the thickness direction, it is easier for the beam to undergo bending deformation around the neutral axis in the width direction. The sheet-like structure concentrates the strain on both sides of the beam, making it easier for strain gauges to efficiently capture the resistance changes caused by deformation on the most deformable plate surface, effectively improving the resolution of related load measurements. At the same time, it causes the second connecting beam to produce more obvious and stable deformation when under stress, enhancing the force transmission efficiency and ensuring the sensitivity and accuracy of force and moment measurements in the corresponding directions.

[0021] Optionally, the width direction of the second connecting beam is parallel to the radial direction of the elastic body.

[0022] By adopting the above technical solution, when subjected to X / Y force or Z-axis moment, the direction of the force can more directly correspond to the thickness direction (the direction most prone to deformation) of the second connecting beam. This makes it easier for the second connecting beam to undergo bending deformation around the neutral axis in the width direction, which facilitates the strain gauge to accurately capture the strain changes caused by deformation, enhances the response sensitivity to relevant loads, and thus improves the accuracy and reliability of X / Y force and Z-axis moment measurement.

[0023] Optionally, four second connecting beams are provided, evenly spaced along the circumference of the elastic body.

[0024] By adopting the above technical solution, the load borne by each second connecting beam can be evenly distributed, avoiding structural damage caused by localized stress concentration, and improving the overall load-bearing capacity and structural stability of the sensor. At the same time, the evenly spaced distribution allows the second connecting beam to produce a symmetrical and consistent deformation response when subjected to force or torque, which facilitates the stable capture of strain changes by strain gauges, reduces measurement deviations caused by uneven distribution, and improves the accuracy and consistency of force and torque measurements in relevant directions.

[0025] Optionally, the first connecting beam and the second connecting beam are staggered in the circumferential direction of the elastic body.

[0026] By adopting the above technical solution, the force transmission path can be optimized, enabling the two types of connecting beams to respond more sensitively and generate corresponding deformations from different circumferential positions when the sensor is subjected to forces and torques in different directions. This avoids mutual interference of force sensing caused by overlapping distributions, while making the circumferential force distribution more uniform. With the help of strain gauges, the deformation differences can be captured more accurately, thereby improving the resolution and accuracy of load measurement in all directions.

[0027] Optionally, the first support, the elastic body, the second support, the plurality of first connecting beams and the plurality of second connecting beams are integrally formed.

[0028] By adopting the above technical solutions, the connection gaps and assembly errors between components can be eliminated, making the force transmission more direct and accurate, avoiding force transmission distortion caused by gaps or improper assembly, thereby significantly improving the measurement accuracy and repeatability of the sensor; at the same time, the integrated molding structure enhances the overall structural strength and stability, reduces the risk of failure caused by loose or damaged component connections, and extends the service life of the sensor.

[0029] Optionally, the first support base is provided with a positioning hole; and / or, the second support base is provided with a positioning hole.

[0030] By adopting the above technical solution, it is easy to accurately connect and position the first support base with other components such as the sensor base or cover plate, which can effectively reduce positional deviations during installation, ensure that the force state of the sensor during operation is consistent with the design expectation, and avoid measurement errors caused by misalignment during installation. At the same time, the setting of positioning holes also improves the convenience and efficiency of installation, ensures the stability of the connection, and enhances the reliability of the overall sensor structure.

[0031] Optionally, the first support and the second support are symmetrically arranged about the elastomer.

[0032] By adopting the above technical solutions, the load distribution is made more uniform, the overall load-bearing capacity and structural stability are enhanced, and the service life of the sensor is extended.

[0033] In summary, this application includes at least one of the following beneficial technical effects:

[0034] 1. The six-dimensional force sensor of this application achieves structural decoupling by having the most easily deformable directions of the first and second connecting beams perpendicular to the most easily deformable direction of the elastic body, and at least two of the most easily deformable directions of the two types of connecting beams are perpendicular to each other. This allows forces and moments in different directions to cause deformation of the corresponding components, reducing mutual interference between measurements in different directions. Combined with the precise capture of deformation by strain gauges, this significantly improves the accuracy, sensitivity, and resolution of load measurements in various directions.

[0035] 2. The first support, the elastic body, and the second support are all formed by a ring-shaped hollow structure, which provides a large space for wiring and can accommodate more lines. This solves the problem of limited wiring capacity in traditional sensors. At the same time, it facilitates the orderly arrangement of lines in the hollow channel, effectively avoids line tangling and interference, and ensures the stability of signal transmission. It is suitable for the high-density wiring needs of humanoid robots and industrial robotic arms.

[0036] 3. The integrated molding of the first support base, elastic body, second support base and connecting beam eliminates the connection gaps and assembly errors between components, making the force transmission more direct and accurate, reducing measurement deviations caused by assembly problems, and improving the measurement accuracy and repeatability of the sensor; at the same time, the symmetrical structural design makes the load distribution more uniform, enhances the overall load-bearing capacity and structural stability, and extends the service life of the sensor. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of the six-dimensional force sensor provided in the embodiments of this application.

[0038] Explanation of reference numerals in the attached figures:

[0039] 1. First support seat; 2. Elastic body; 3. Second support seat; 4. First connecting beam; 5. Second connecting beam; 6. Positioning hole. Detailed Implementation

[0040] The following will be combined with the appendix Figure 1 The technical solutions in the embodiments of this application are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0041] This application discloses a six-dimensional force sensor. (Refer to...) Figure 1 The six-dimensional force sensor includes a first support base 1, an elastic body 2, and a second support base 3, all arranged in a ring shape and spaced apart along the central axis. Multiple first connecting beams 4 connect the first support base 1 and the elastic body 2, and multiple second connecting beams 5 connect the second support base 3 and the elastic body 2. When the first connecting beams 4 and 5 deform, the elastic body 2 can undergo slight relative movement with respect to the first support base 1 and the second support base 3 in the Z-axis direction and in directions related to the Z-axis torque. Both the first support base 1 and the second support base 3 are provided with positioning holes 6 for connection to the base or cover plate of the six-dimensional force sensor.

[0042] The first support 1, the elastic body 2, and the second support 3 are all annular, making the six-dimensional force sensor a hollow structure, forming a hollow channel. In humanoid robots and industrial robotic arms, a large number of wires are needed for signal transmission and power supply. Traditional six-dimensional sensors are mostly solid or partially perforated, limiting wiring capacity. This application achieves an axially unobstructed channel through a fully annular structure. This hollow structure provides a larger space for wiring, accommodating more wires and solving the problem of high-density wiring. Simultaneously, the wires can be arranged orderly within the hollow channel, effectively avoiding tangling and interference between wires and ensuring the stability of signal transmission.

[0043] The elastic body 2 is located at the center of the entire six-dimensional sensor, connecting the first support 1 and the second support 3 to form a two-layer I-beam structure. It has high bending stiffness and provides superior load-bearing capacity. When subjected to external force, the elastic body 2 located in the middle can produce large deformation, enabling the sensor to obtain high sensitivity. Secondly, the elastic body 2 is located at the center of the entire six-dimensional sensor and can be protected by the sensor shell surrounding it, reducing interference and damage from the external environment to the elastic body 2 and extending the service life of the sensor.

[0044] Specifically, the first support 1, the elastic body 2, and the second support 3 are all annular. The first support 1 and the second support 3 are symmetrically arranged about the elastic body 2. This symmetrical structure allows the support seats on both sides (i.e., the first support 1 and the second support 3) to evenly distribute the load when the sensor is under stress, reducing the additional stress caused by structural asymmetry and improving the measurement accuracy and stability of the sensor. When subjected to large loads, the symmetrical structure can make the force distribution more uniform, thereby improving the overall load-bearing capacity of the sensor.

[0045] In this embodiment, the elastomer 2 is a ring-shaped sheet structure, suitable for high-precision measurement requirements of Z-axis loads (Fz, Mx, My) in scenarios such as humanoid robot joint drive modules and industrial robotic arm end effectors. The most easily deformable direction of the elastomer 2 is the central axis direction (Z-axis), and the ring-shaped sheet elastomer 2 has the lowest stiffness and the highest flexibility in the central axis direction. Under normal operating loads, the force (Fz) applied along the Z-axis or the torque (Mx, My) applied around an axis perpendicular to the Z-axis (X / Y axis) will mainly induce the strain response of the elastomer 2 in the Z-axis, ensuring sufficiently high measurement sensitivity for Z-axis loads (Fz, Mx, My). Placing strain gauges on the upper and lower surfaces of the elastomer 2 can improve the signal-to-noise ratio of the strain signal. The strain gauges are directly located in the region of maximum strain gradient, which can capture the micro-deformation induced by Z-axis loads to the maximum extent.

[0046] The most easily deformable directions of the first connecting beam 4 and the second connecting beam 5 are both perpendicular to the most easily deformable direction of the elastic body 2. Since the most easily deformable directions of the multiple first connecting beams 4 and the multiple second connecting beams 5 have at least two perpendicular directions, the sensor is structurally decoupled, allowing forces and moments in different directions to cause deformation of the corresponding components, reducing mutual interference between measurements in different directions. During the measurement process, the Z-axis load is mainly sensed by the elastic body 2, while the X and Y-axis forces and moments about the Z-axis are mainly sensed by the first connecting beams 4 and the second connecting beams 5, thereby improving the accuracy of the measurement.

[0047] In this embodiment, both the first connecting beam 4 and the second connecting beam 5 are sheet-like and cuboid, causing the strain on the beams to concentrate on both sides. The direction of most likely deformation is the thickness direction, which is the load direction that causes the beams (i.e., the first connecting beam 4 and the second connecting beam 5) to bend about their width neutral axis. When the X / Y forces (Fx, Fy) and the Z-axis moment (Mz) act on the beam thickness direction, the beam is most likely to bend about its width neutral axis.

[0048] Specifically, the length direction of the first connecting beam 4 is parallel to the central axis of the elastic body 2, and the width direction is perpendicular to the radial direction of the elastic body 2, with the plate surface facing the axis of the elastic body 2. There are four first connecting beams 4, which are evenly spaced along the circumference of the elastic body 2.

[0049] The length of the second connecting beam 5 is parallel to the central axis of the elastic body 2, and the width is parallel to the radial direction of the elastic body 2. Its side faces the axis of the elastic body 2. There are four second connecting beams 5, which are evenly spaced along the circumference of the elastic body 2.

[0050] The first connecting beam 4 and the second connecting beam 5 are staggered around the circumference of the elastic body. Strain gauges are provided on the most deformable surfaces (i.e., the plate surfaces, planes parallel to the length and width) of both the first connecting beam 4 and the second connecting beam 5 to most effectively capture the bending strain caused by the load in the thickness direction, making it easier to collect the deformation of the beam and thus change the resistance value, which can effectively improve the resolution of the sensor.

[0051] The four first connecting beams 4 and the four second connecting beams 5 are evenly distributed circumferentially, which enables the load to be evenly distributed across the beams, avoiding damage caused by excessive local stress. The staggered arrangement further optimizes the force transmission path. When the sensor is subjected to forces and moments in different directions, the staggered connecting beams can respond more sensitively and produce corresponding deformations, improving the sensor's measurement accuracy of loads in all directions.

[0052] The first connecting beam 4 and the second connecting beam 5 are arranged vertically, which further enhances the stability of the structure and the efficiency of force transmission. When the beams are subjected to vertical forces, they can better exert their bending characteristics and produce significant deformation. At the same time, it is also beneficial to the overall layout of the sensor and reduces the size of the sensor.

[0053] In this application, the six-dimensional force sensor adopts a symmetrical structure, with the first connecting beam 4 and the second connecting beam 5 arranged vertically, which enables the six-dimensional force sensor to be structurally decoupled.

[0054] The first support 1, the elastic body 2, the second support 3, multiple first connecting beams 4, and multiple second connecting beams 5 are integrally formed, which can eliminate the connection gaps and assembly errors between the components, significantly improving the measurement accuracy and reliability of the sensor. In traditional assembled sensors, gaps and assembly errors between the components can lead to inaccurate force transmission, resulting in repeatability errors.

[0055] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation" and "connection" 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 mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0056] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application 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, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0057] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A six-dimensional force sensor, characterized in that, It includes a first support seat (1), an elastic body (2) and a second support seat (3) arranged in a ring shape and spaced apart along the central axis. A plurality of first connecting beams (4) connect the first support seat (1) and the elastic body (2), and a plurality of second connecting beams (5) connect the second support seat (3) and the elastic body (2). Among them, the most easily deformable directions of the first connecting beam (4) and the second connecting beam (5) are perpendicular to the most easily deformable direction of the elastic body (2), and the most easily deformable directions of the multiple first connecting beams (4) and the multiple second connecting beams (5) have at least two perpendicular directions; strain gauges are provided on the most easily deformable surfaces of the elastic body (2), the first connecting beam (4) and the second connecting beam (5).

2. The six-dimensional force sensor according to claim 1, characterized in that, The elastomer (2) is an annular sheet, and the most easily deformable direction of the elastomer (2) is the central axis direction.

3. The six-dimensional force sensor according to claim 1, characterized in that, The first connecting beam (4) is sheet-like, and the most easily deformable direction of the first connecting beam (4) is the thickness direction.

4. The six-dimensional force sensor according to claim 3, characterized in that, The width direction of the first connecting beam (4) is perpendicular to the radial direction of the elastic body (2).

5. The six-dimensional force sensor according to claim 4, characterized in that, The first connecting beam (4) is provided in four parts, which are evenly spaced along the circumference of the elastic body (2).

6. The six-dimensional force sensor according to claim 1, characterized in that, The second connecting beam (5) is sheet-like, and the most easily deformable direction of the second connecting beam (5) is the thickness direction.

7. The six-dimensional force sensor according to claim 6, characterized in that, The width direction of the second connecting beam (5) is parallel to the radial direction of the elastic body (2).

8. The six-dimensional force sensor according to claim 7, characterized in that, The second connecting beam (5) has four beams, which are evenly spaced along the circumference of the elastic body (2).

9. The six-dimensional force sensor according to claim 1, characterized in that, The first connecting beam (4) and the second connecting beam (5) are staggered in the circumferential direction of the elastic body (2); and / or, The first support base (1), the elastic body (2), the second support base (3), the multiple first connecting beams (4) and the multiple second connecting beams (5) are integrally formed.

10. The six-dimensional force sensor according to claim 1, characterized in that, The first support base (1) and the second support base (3) are provided with positioning holes (6); and / or, The first support (1) and the second support (3) are symmetrically arranged about the elastic body (2).

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