Six-dimensional force sensor

Abstract

The invention relates to the technical field of force sensors, in particular to a six-dimensional force sensor which comprises a first supporting seat, an elastic body and a second supporting seat which are annular and are sequentially arranged at intervals in the direction of a central shaft, and a plurality of first connecting beams are connected between the first supporting seat and the elastic body. A plurality of second connecting beams are connected between the second supporting seat and the elastic body; wherein the most easily-deformed directions of the first connecting beams and the second connecting beams are perpendicular to the most easily-deformed direction of the elastic body, and the most easily-deformed directions of the first connecting beams and the second connecting beams at least have two perpendicular directions; and strain gauges are arranged on the surfaces, which are easy to deform, of the elastic body, the first connecting beam and the second connecting beam. The whole six-dimensional force sensor is of a hollow structure, a large threading and wiring space is provided, more lines can be contained, the problem that the wiring capacity of a traditional sensor is limited is solved, meanwhile, orderly arrangement of the lines is facilitated, winding and interference are avoided, and stable signal transmission is guaranteed.

Description

Technical Field

[0001] The present application relates to the technical field of force sensors, and in particular to a six-dimensional force sensor. Background Art

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

[0003] The six-dimensional force sensor is generally installed at the end of the partial execution unit of a humanoid robot or industrial robot arm, just like a human wrist and ankle. After installation, it can better realize the force control of the robot. It is mainly composed of an elastomer, a strain gauge and a circuit board; the elastomer is a circumferential support, which is a medium used to bear deformation; the strain gauge is a device used to measure the local deformation of the elastomer, which can convert the deformation of the elastomer into the deformation of the strain gauge, and further measure the magnitude of the output force through the proportional relationship between the deformation and resistance; the circuit board is also called the acquisition card board, which is a system for data processing, which converts the measured strain gauge pressure data into a digital signal that the machine can understand; when the main control receives the digital signal, the machine can achieve the purpose of knowing the weight.

[0004] In the prior art, for example, the invention patent with publication number CN109238529B discloses a six-dimensional sensor, which is mainly composed of a circumferential support, a center platform, and radial beams and floating beams with strain gauges. The sensor can collect deformation information through the strain gauges on the radial beams and floating beams. The invention patent with publication number CN118067296B discloses a low-stress six-dimensional force sensor, which is mainly composed of a housing, a center support platform, and multiple elastic beams located circumferentially of the center support platform and equipped with strain gauges. The invention patent with publication number CN116164873B discloses a six-dimensional force sensor, whose sensor body is mainly composed of a mounting base, a center axis, and multiple elastic beams located circumferentially of the center axis and equipped with strain gauges.

[0005] When applied to humanoid robots and other devices that require multiple sensors to work together to collect force information on multiple parts of the body, a large number of lines need to be arranged to transmit data and perform integrated processing. The above-mentioned six-dimensional sensor structure has a compact internal space. Due to the complex line integration, it is prone to entanglement and extrusion problems, which is not conducive to line threading and laying; the system maintenance is difficult and the cost of line fault troubleshooting is high; the space utilization rate is low when multiple sensors are arranged, which affects the overall structural design of the robotic arm. Summary of the Invention

[0006] In order to solve the problem that the internal space of the six-dimensional sensor structure is compact, and due to the complex circuit integration, it is easy to get entangled and squeezed, which is not conducive to threading and laying the lines, the present application provides a six-dimensional force sensor.

[0007] The six-dimensional force sensor provided in this application adopts the following technical solution: A six-dimensional force sensor includes a first support base, an elastic body, and a second support base, all of which are annular and arranged in sequence along a central axis. A plurality of first connecting beams are connected between the first support base and the elastic body, and a plurality of second connecting beams are connected between the second support base and the elastic body. Among them, the most easily deformed directions of the first connecting beam and the second connecting beam are both perpendicular to the most easily deformed direction of the elastic body, and the most easily deformed directions of multiple first connecting beams and multiple second connecting beams have at least two perpendicular directions; strain gauges are provided on the most easily deformed surfaces of the elastic body, the first connecting beam and the second connecting beam.

[0008] By adopting the above technical solution, the first support seat, the elastomer and the second support seat are all annular, so that the six-dimensional force sensor forms a hollow structure as a whole, providing a larger wiring space, which can accommodate more lines and solve the problem of limited wiring capacity of traditional sensors. At the same time, it is convenient for the orderly arrangement of lines to avoid entanglement and interference, and ensure stable signal transmission; and the most easily deformed directions of the first connecting beam and the second connecting beam are perpendicular to the most easily deformed direction of the elastomer, and the most easily deformed directions of the multiple first and second connecting beams have at least two perpendicular directions. Combined with the arrangement of strain gauges on the most easily deformed surfaces of each component, structural decoupling is achieved, reducing mutual interference in measurements in various directions, allowing strain gauges to capture deformation more efficiently, and improving the accuracy, sensitivity and resolution of load measurements in various directions.

[0009] Optionally, the elastic body is in the shape of an annular sheet, and the direction in which the elastic body is most easily deformed is the direction of the central axis.

[0010] By adopting the above-mentioned technical solution, the elastomer has lower stiffness and higher flexibility in the direction of the central axis. When subjected to force along the Z-axis or torque around an axis perpendicular to the Z-axis, it can mainly induce a 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 will produce a symmetrical tensile and compressive strain field when subjected to force in the Z-direction, which makes it easier for 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.

[0011] Optionally, the first connecting beam is sheet-shaped, and the direction in which the first connecting beam is most easily deformed is the thickness direction.

[0012] By adopting the above technical solution, when X / Y forces and Z-axis moments act on the first connecting beam in the thickness direction, the first connecting beam is most likely to bend and deform around the neutral axis in the width direction. The sheet-like structure allows the strain on the first connecting beam to be concentrated on both sides of the first connecting beam. The strain gauges are laid on the plate surface that is most prone to deformation, making it easier to detect the deformation of the first connecting beam and thus change the resistance value, which can effectively improve the resolution of the sensor for measuring X / Y forces and Z-axis moments.

[0013] Optionally, the width direction of the first connecting beam is perpendicular to the radial direction of the elastic body.

[0014] By adopting this technical solution, when subjected to X / Y forces or moments about the Z axis, the force acts more directly along the thickness of the first connecting beam (the direction most susceptible to deformation), making it more susceptible to bending deformation about its neutral axis in the width direction, thereby enhancing its sensitivity to the associated loads. This directional arrangement also optimizes the force transmission path through the first connecting beam, making deformation more stable and concentrated, facilitating the strain gauge's precise capture of strain changes and improving the accuracy and resolution of corresponding force and moment measurements. The vertical orientation of the sheet-like first connecting beam enhances structural stability and force transmission efficiency, allowing it to better utilize its bending properties and produce significant deformation when subjected to vertical forces. This facilitates the overall sensor layout and reduces its size.

[0015] Optionally, there are four first connecting beams, which are evenly spaced along the circumference of the elastomer.

[0016] By adopting the above technical solution, the load can be evenly distributed on each first connecting beam, avoiding structural damage caused by excessive local force, and improving the stability and bearing capacity of the overall structure; at the same time, the evenly spaced distribution allows the first connecting beam to produce symmetrical and balanced deformation responses when subjected to forces or moments in different directions, reducing measurement deviations caused by uneven distribution. In combination with strain gauges, the strain changes of each beam can be more stably captured, improving the accuracy and consistency of the corresponding force and moment measurements.

[0017] Optionally, the second connecting beam is sheet-shaped, and the direction in which the second connecting beam is most easily deformed is the thickness direction.

[0018] By adopting the above technical solution, when subjected to X / Y forces or torques around the Z axis in the thickness direction, bending deformation around the neutral axis in the width direction can occur more easily. The sheet structure allows the strain to be concentrated on both sides of the beam, making it easier for the strain gauge to efficiently capture the resistance changes caused by deformation on the plate surface that is most prone to deformation, effectively improving the resolution of related load measurements; at the same time, it promotes the second connecting beam to produce more obvious and stable deformation when subjected to force, enhances the force transmission efficiency, and ensures the sensitivity and accuracy of the corresponding directional force and torque measurement.

[0019] Optionally, the width direction of the second connecting beam is parallel to the radial direction of the elastic body.

[0020] By adopting the above technical solution, when subjected to X / Y force or moment around the Z axis, the direction of force can more directly correspond to the thickness direction of the second connecting beam (the direction most susceptible to deformation), making the second connecting beam more susceptible to bending deformation around the neutral axis in the width direction. This makes it easier for the strain gauge to accurately capture the strain changes caused by the deformation, enhances the response sensitivity to related loads, and thus improves the accuracy and reliability of the measurement of X / Y force and Z axis moment.

[0021] Optionally, four second connecting beams are provided and are evenly spaced along the circumference of the elastic body.

[0022] By adopting the above technical solution, the load borne by each second connecting beam can be evenly shared, avoiding structural damage caused by local force 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, making it easier for the strain gauge to stably capture strain changes, reducing measurement deviations caused by uneven distribution, and improving the accuracy and consistency of force and torque measurements in related directions.

[0023] Optionally, the first connecting beam and the second connecting beam are staggered in the circumferential direction of the elastic body.

[0024] By adopting the above technical solution, the force transmission path can be optimized, so that when the sensor is subjected to forces and moments in different directions, the two types of connecting beams can respond more sensitively and produce corresponding deformations from different circumferential positions, avoiding mutual interference of force sensing due to overlapping distribution. At the same time, the circumferential force distribution is made more uniform, and the strain gauges can be used to more accurately capture the respective deformation differences, thereby improving the resolution and accuracy of load measurements in various directions.

[0025] Optionally, the first support seat, the elastic body, the second support seat, the plurality of first connecting beams and the plurality of second connecting beams are integrally formed.

[0026] By adopting the above technical solution, 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 one-piece 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.

[0027] Optionally, a positioning hole is provided on the first support base; and / or a positioning hole is provided on the second support base.

[0028] By adopting the above technical solution, the first support base and other components such as the base or cover of the sensor can be accurately connected and positioned, which can effectively reduce the position deviation during the installation process, ensure that the force state of the sensor during operation is consistent with the design expectations, and avoid measurement errors caused by installation misalignment; at the same time, the setting of the positioning holes also improves the convenience and efficiency of installation, ensures the stability of the connection, and enhances the reliability of the overall structure of the sensor.

[0029] Optionally, the first support seat and the second support seat are symmetrically arranged with respect to the elastic body.

[0030] 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.

[0031] In summary, this application includes at least one of the following beneficial technical effects: 1. The six-dimensional force sensor of the present application realizes structural decoupling by making the most easily deformed directions of the first connecting beam and the second connecting beam perpendicular to the most easily deformed direction of the elastic body, and the most easily deformed directions of the two types of connecting beams have at least two perpendicular directions, so that forces and moments in different directions can cause deformation of corresponding components respectively, reducing mutual interference in measurements in various directions, and cooperating with the strain gauge to accurately capture deformation, thereby significantly improving the accuracy, sensitivity and resolution of load measurements in various directions.

[0032] 2. The first support base, the elastomer and the second support base are all hollow structures formed in a ring shape, which provides a larger space for wiring and can accommodate more lines, solving the problem of limited wiring capacity of traditional sensors. At the same time, it is convenient for the lines to be arranged in an orderly manner in the hollow channel, effectively avoiding line entanglement and interference, ensuring the stability of signal transmission, and adapting to the high-density wiring requirements of scenarios such as humanoid robots and industrial robotic arms.

[0033] 3. The one-piece molding of the first support base, elastomer, second support base and connecting beam eliminates the connection gaps and assembly errors between the components, making the force transmission more direct and accurate, reducing the measurement deviation 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the structure of the six-dimensional force sensor provided in the embodiment of the present application.

[0035] Description of reference numerals: 1. First support seat; 2. Elastic body; 3. Second support seat; 4. First connecting beam; 5. Second connecting beam; 6. Positioning hole. DETAILED DESCRIPTION

[0036] The following will be combined with the Figure 1 , clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of this application.

[0037] The embodiment of the present application discloses a six-dimensional force sensor. Figure 1 The six-dimensional force sensor includes a first support base 1, an elastic body 2, and a second support base 3, all of which are annular and arranged in sequence along the central axis. A plurality of first connecting beams 4 are connected between the first support base 1 and the elastic body 2, and a plurality of second connecting beams 5 are connected between the second support base 3 and the elastic body 2. When the first connecting beams 4 and the second connecting beams 5 are deformed, the elastic body 2 can undergo slight relative movement relative to the first support base 1 and the second support base 3 in the Z-axis direction and in a direction related to the Z-axis torque. The first support base 1 and the second support base 3 are both provided with positioning holes 6 for connecting to the base or cover plate of the six-dimensional force sensor.

[0038] The first support seat 1, the elastomer 2 and the second support seat 3 are all ring-shaped, so that the six-dimensional force sensor is a hollow structure as a whole, forming a hollow channel. In humanoid robots and industrial robotic arms, a large number of lines are required for signal transmission and power supply. Traditional six-dimensional sensors are mostly solid or partially open, and the wiring capacity is limited. The present application realizes an axial unobstructed channel through a full ring. The hollow structure can provide a larger threading and wiring space, which can accommodate more lines and solve the pain points of high-density wiring. At the same time, the lines can be arranged in an orderly manner in the hollow channel, effectively avoiding entanglement and interference between the lines, and ensuring the stability of signal transmission.

[0039] The elastomer 2 is located at the center of the six-dimensional sensor as a whole, connecting the first support seat 1 and the second support seat 3 to form a two-layer I-shaped structure with high bending stiffness and provide better high load-bearing capacity. When subjected to external force, the elastomer 2 located in the middle can produce a large deformation, so that the sensor has high sensitivity; secondly, the elastomer 2 is located at the center of the six-dimensional sensor as a whole and can be protected by the sensor housing installed on the periphery, reducing the interference and damage of the external environment to the elastomer 2 and extending the service life of the sensor.

[0040] Specifically, the first support base 1, elastic body 2, and second support base 3 are all circular rings, and are symmetrically arranged about the elastic body 2. This symmetrical structure allows the support bases on both sides (i.e., the first support base 1 and the second support base 3) to evenly share the load when the sensor is subjected to force, reducing the additional stress caused by structural asymmetry and improving the sensor's measurement accuracy and stability. When subjected to heavy loads, the symmetrical structure ensures more even force distribution, thereby enhancing the sensor's overall load-bearing capacity.

[0041] In this embodiment, the elastic body 2 is an annular sheet structure, suitable for the high-precision measurement requirements of Z-direction loads (Fz, Mx, My) in scenarios such as humanoid robot joint drive modules and industrial robot arm end effectors. The elastic body 2 is most susceptible to deformation along its central axis (Z-axis), and the annular sheet-shaped elastic body 2 has the lowest stiffness and highest compliance in this direction. Under normal operating loads, the force (Fz) applied along the Z-axis or the torque (Mx, My) applied about axes perpendicular to the Z-axis (X / Y axes) primarily induces a strain response in the Z-direction of the elastic body 2, ensuring sufficiently high measurement sensitivity for the Z-direction loads (Fz, Mx, My). Strain gauges applied on the upper and lower surfaces of the elastic body 2 improve the signal-to-noise ratio of the strain signal. The strain gauges are directly located in the area of ​​maximum strain gradient, maximizing the capture of microscopic deformations caused by the Z-direction load.

[0042] The most susceptible deformation directions of the first and second connecting beams 4, 5 are both perpendicular to the most susceptible deformation direction of the elastic body 2. The multiple first connecting beams 4 and multiple second connecting beams 5 have at least two perpendicular directions of most susceptible deformation, achieving structural decoupling of the sensors. This allows forces and moments in different directions to cause deformation of their respective components, reducing mutual interference between measurements in different directions. During measurement, the Z-direction load is primarily sensed by the elastic body 2, while the X- and Y-direction forces and moments about the Z axis are primarily sensed by the first and second connecting beams 4, 5, thereby improving measurement accuracy.

[0043] In this embodiment, both the first and second connecting beams 4 and 5 are sheet-shaped and rectangular parallelepiped, concentrating strain on the beams on their sides. Deformation is most likely to occur along the thickness direction, i.e., the direction of load that causes the beams (i.e., the first and second connecting beams 4 and 5) to bend about their neutral axes in the width direction. When X / Y forces (Fx, Fy) and Z-axis moment (Mz) act along the thickness of the beams, the beams are most likely to bend about their neutral axes in the width direction.

[0044] Specifically, the length direction of the first connecting beam 4 is parallel to the central axis direction of the elastic body 2, the width direction is perpendicular to the radial direction of the elastic body 2, and the plate surface faces 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.

[0045] The second connecting beam 5 is parallel to the central axis of the elastic body 2 in length and radial direction, and its side faces the axis of the elastic body 2. There are four second connecting beams 5, evenly spaced along the circumference of the elastic body 2.

[0046] The first and second connecting beams 4 and 5 are staggered around the circumference of the elastic body 2. Strain gauges are installed on the most deformable surfaces of the first and second connecting beams 4 and 5 (i.e., the plate surfaces, parallel to the length and width planes) to most effectively capture the bending strain caused by thickness-direction loads. This makes it easier to detect beam deformation and thus changes in resistance, effectively improving the sensor's resolution.

[0047] The four first connecting beams 4 and the four second connecting beams 5 are evenly distributed along the circumference, distributing the load evenly across the beams and preventing damage caused by localized excessive forces. 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 respond more sensitively and deform accordingly, improving the sensor's measurement accuracy for loads in all directions.

[0048] 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 beam is subjected to vertical force, it can better exert its bending characteristics and produce obvious deformation. At the same time, it is also beneficial to the overall layout of the sensor and reduces the volume of the sensor.

[0049] In the present application, the six-dimensional force sensor adopts a symmetrical structure, and the first connecting beam 4 and the second connecting beam 5 are vertically arranged, which can achieve structural decoupling of the six-dimensional force sensor.

[0050] The first support base 1, elastic body 2, second support base 3, multiple first connecting beams 4, and multiple second connecting beams 5 are integrally formed, eliminating gaps and assembly errors between the components, significantly improving the sensor's measurement accuracy and reliability. In traditional assembled sensors, gaps and assembly errors between the components can lead to inaccurate force transmission and thus repeatability errors.

[0051] In the description of this application, it should be noted that, unless otherwise specified or limited, the terms "mounted" and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; and direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0052] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of the present application, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0053] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A six-dimensional force sensor, characterized in that: The invention comprises a first support seat (1), an elastic body (2) and a second support seat (3), all of which are annular and arranged in sequence along the central axis, wherein a plurality of first connecting beams (4) are connected between the first support seat (1) and the elastic body (2), and a plurality of second connecting beams (5) are connected between the second support seat (3) and the elastic body (2); The most easily deformed directions of the first connecting beam (4) and the second connecting beam (5) are both perpendicular to the most easily deformed direction of the elastic body (2), and the most easily deformed directions of the plurality of first connecting beams (4) and the plurality of second connecting beams (5) have at least two perpendicular directions; and strain gauges are provided on the most easily deformed 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 elastic body (2) is in the shape of an annular sheet, and the direction in which the elastic body (2) is most easily deformed is the direction of the central axis.

3. The six-dimensional force sensor according to claim 1, characterized in that: The first connecting beam (4) is sheet-shaped, and the direction in which the first connecting beam (4) is most easily deformed 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: Four first connecting beams (4) are provided and 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-shaped, and the direction in which the second connecting beam (5) is most easily deformed 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: Four second connecting beams (5) are provided and 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 seat (1), the elastic body (2), the second support seat (3), the plurality of first connecting beams (4) and the plurality of second connecting beams (5) are integrally formed.

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

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