A full-plane six-dimensional force sensor elastic body

Abstract

A full-plane six-axis force sensor elastomer relates to the field of six-axis force sensor elastomers. The present invention primarily addresses the difficulty of existing six-axis force sensor elastomers in achieving both small size, light weight, and high load-bearing capacity. The elastomer described in this application includes an outer ring and an inner ring. The outer ring is sleeved on the outside of the inner ring. The outer and inner rings are connected by four beam assemblies. The four beam assemblies are equidistantly arranged between the outer and inner rings along the circumferential direction, and one end of each beam assembly is integrally formed with the outer ring, and the other end of each beam assembly is integrally formed with the inner ring. Each beam assembly is mounted with a strain measurement unit assembly. This application is primarily used as the elastomer structure in a full-plane six-axis force sensor.

Description

Technical Field

[0001] The present invention relates to the field of six-dimensional force sensor elastomers, and in particular to a full-plane six-dimensional force sensor elastomer. Background Art

[0002] The demand for robots in new scenarios is accelerating the demand for comprehensive performance in six-dimensional force sensors. Nowadays, people not only expect robots to have stable and accurate movements but also to be able to operate under heavy loads. Six-dimensional force sensors, capable of simultaneously sensing full force in three dimensions, have become a key component of robots. This is inevitably leading to a rapid increase in demand for six-dimensional force sensors with high load capacities.

[0003] Existing six-axis force sensors generally increase their load-bearing capacity by increasing thickness, which adds unnecessary size and mass. If this increase in thickness is avoided, increasing the load-bearing capacity by adding multiple load-bearing beams results in unnecessary increases in lateral stiffness, significantly reducing lateral sensitivity. Furthermore, the strain measurement units of existing six-axis force sensors are often arranged on different surfaces of the strain beam, making the placement process cumbersome and inefficient.

[0004] Chinese patent CN1220037C discloses a miniature full-plane six-dimensional force and torque sensor. The sensor has a flat, disc-shaped structure and consists of a central body, three outer ring beams surrounding the central body at 60-degree angles to each other, three inner ring beams radially arranged within the outer ring beams at 120-degree angles to each other, and strain gauges. The three outer ring beams are each composed of two thin, sheet-shaped strain beams, the inner ends of the three inner ring beams being connected to the central body, and the outer ends of the three inner ring beams being connected to the intersections between the two outer ring beams. The central body, outer ring beams, and inner ring beams are connected to form an integrated structure, with strain gauges provided on each outer and inner ring beam. The sensor's full-plane structure facilitates the placement of strain measurement units and is suitable for micromachining. It is also compact and highly accurate, making it suitable for use in the fingertips of second-generation humanoid robot dexterous hands, enhancing the intelligence of the entire robotic system. However, it suffers from the difficulty of balancing small size, light weight, and high load capacity.

[0005] Chinese patent CN115683434B discloses a six-axis force / torque measurement device for a space manipulator adapted for crawling inchworms. The device uses a flexible load-sharing beam to bear most of the force / torque load, which not only improves the rigidity of the measuring device but also serves as an overload protection. A T-shaped sensitive beam with a special structure is used to bear a small part of the force / torque load, which serves as a detection and measurement function. According to the actual working conditions, the rigidity ratio of the load-sharing beam and the sensitive beam is reasonably distributed, which solves the contradictory relationship between high rigidity, large overload and sensitivity, making it more suitable for space manipulators that crawl inchworms. Although this structure improves the measurement rigidity of the sensor, the rigidity improvement is all-round, which will lead to an excessive increase in radial rigidity that does not need to be improved, resulting in a significant reduction in lateral sensitivity. In addition, the arrangement positions of its strain measurement units are located in different planes, and the sputtering process cannot be used to arrange the strain measurement units. The arrangement of the strain measurement units is inconsistent and inefficient. Summary of the Invention

[0006] The present invention mainly addresses the problem that existing six-dimensional force sensor elastic bodies are difficult to achieve both small size, light weight and large load-bearing capacity, and thus provides a full-plane six-dimensional force sensor elastic body;

[0007] A full-plane six-dimensional force sensor elastic body, the elastic body comprising an outer ring and an inner ring, the outer ring being sleeved on the outside of the inner ring, the outer ring and the inner ring being connected by four beam assemblies, the four beam assemblies being equidistantly arranged between the outer ring and the inner ring along the circumferential direction, one end of each beam assembly being integrally formed with the outer ring, the other end of each beam assembly being integrally formed with the inner ring, and a strain measurement unit assembly being mounted on each beam assembly;

[0008] Furthermore, the elastic body also includes four double-rigidity reinforcement beams, each of which is located in the middle of two adjacent beam body components, and one end of each double-rigidity reinforcement beam is integrally formed with the outer ring, and the other end of each double-rigidity reinforcement beam is integrally formed with the inner ring.

[0009] Furthermore, the dual-rigidity reinforcement beam includes four reinforcement beam bodies, which are sequentially connected end to end in a diamond-shaped arrangement. Two oppositely disposed tips of the dual-rigidity reinforcement beam serve as connection portions with the outer ring and the inner ring, one tip being integrally formed with the outer ring, and the other tip being integrally formed with the inner ring.

[0010] Furthermore, the beam assembly includes an inner beam and two parallel beams, one end of the inner beam is integrally formed with the inner ring, and the two parallel beams are oppositely arranged on both sides of the other end of the inner beam, and one end of each parallel beam is integrally formed with the inner beam through a flexible beam, and the other end of each parallel beam is integrally formed with the outer ring, each flexible beam and its corresponding parallel beam are located on the same center line, and each flexible beam is perpendicular to its corresponding inner beam;

[0011] Furthermore, the strain measurement unit assembly includes a shear strain measurement unit and two tension and compression strain measurement unit groups, the shear strain measurement unit is installed on the top of the inner beam, and each tension and compression strain measurement unit group is correspondingly installed on the top of a parallel beam;

[0012] Furthermore, each tension and compression strain measurement unit group includes two tension and compression strain measurement units, and the two tension and compression strain measurement units are symmetrically installed at both ends of the top of the parallel beam along the center line of the length direction of the parallel beam:

[0013] Furthermore, the shear strain measuring unit located on the inner beam and the tension and compression strain measuring unit located on the parallel beam are both located in the same plane;

[0014] Furthermore, six inner ring through holes are processed on the top of the inner ring at equal intervals along the circumferential direction, and two of the six inner ring through holes are respectively arranged to correspond to the two oppositely arranged inner beams;

[0015] Furthermore, eight outer ring through holes are machined on the top of the outer ring along the circumferential direction, and four of the eight outer ring through holes are respectively located in correspondence with one of the double-rigidity reinforcement beams, and the other four of the eight outer ring through holes are respectively located in correspondence with one of the inner beams;

[0016] Furthermore, the outer ring, inner ring, inner beam, double-rigidity reinforced beam, flexible beam and parallel beam are all made of aluminum alloy, stainless steel or alloy steel;

[0017] The beneficial effects of this application compared to the prior art are as follows:

[0018] 1. The present invention provides a full-plane six-dimensional force sensor elastomer, which uses a flexible beam to connect the parallel beam and the inner beam. When a tangential force Fx or Fy perpendicular to the thickness direction of the flexible beam is applied, the stiffness along the length and height directions of the flexible beam is much greater than the stiffness along the thickness direction, resulting in a small coupling effect with the My or Mx direction, thereby reducing the inter-dimensional coupling. Since the effects of Mz and Fz are relatively independent, their coupling effect is also small. By placing the parallel beam between the flexible beam and the outer ring, and the flexible beam on the center line of the parallel beam, the sensor size is less affected by the size of the parallel beam, making the elastomer structure more compact. At the same time, this arrangement scheme also reduces the distance from the flexible beam to the center of the sensor, thereby reducing the torsional deformation of the flexible beam when subjected to force, and improving the stiffness and sensitivity of the elastomer.

[0019] 2. The present invention provides a full-plane six-dimensional force sensor elastomer, which uses dual-rigidity reinforcement beams to improve the axial stiffness without changing the lateral sensitivity of the elastomer, thereby reducing the thickness of the elastomer. At the same time, it can avoid the problem of excessively increasing the thickness of the parallel beams to increase the axial stiffness, and avoid excessive strain differences in the strain measurement areas of the same parallel beams, thereby improving the measurement sensitivity of the elastomer in the Fz, Mx and My directions.

[0020] 3. The present invention provides a full-plane six-dimensional force sensor elastomer, which is designed as a full-plane structure so that all strain measurement units are located in the same plane of the elastomer. The strain measurement units can be arranged on the elastomer through a sputtering process, thereby improving the arrangement accuracy and efficiency of the strain measurement units. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the overall structure of the elastic body of a full-plane six-dimensional force sensor described in this application;

[0022] In the figure, 1 is outer ring, 2 is outer ring through hole, 3 is flexible beam, 4 is parallel beam, 5 is double-rigidity reinforced beam, 6 is inner beam, 7 is inner ring, 8 is inner ring through hole, 9 is pin hole, 10 is tensile strain measuring unit and 11 is shear-compression strain measuring unit. DETAILED DESCRIPTION

[0023] Specific implementation method 1: Combination Figure 1 To describe this embodiment, a full-plane six-dimensional force sensor elastomer is provided in this embodiment. The elastomer includes an outer ring 1 and an inner ring 7. The outer ring 1 is sleeved on the outside of the inner ring 7. The outer ring 1 and the inner ring 7 are connected by four beam assemblies. The four beam assemblies are equidistantly arranged between the outer ring 1 and the inner ring 7 along the circumferential direction, and one end of each beam assembly is integrally formed with the outer ring 1, and the other end of each beam assembly is integrally formed with the inner ring 7. A strain measurement unit assembly is installed on each beam assembly.

[0024] Specific implementation method 2: Combination Figure 1 This embodiment differs from the first embodiment in that the elastic body further comprises four dual-rigidity reinforcement beams 5, each located directly between two adjacent beam body assemblies. One end of each dual-rigidity reinforcement beam 5 is integrally formed with the outer ring 1, and the other end is integrally formed with the inner ring 7. The remaining components and connection methods are the same as those of the first embodiment.

[0025] Specific implementation method three: Combination Figure 1To explain this embodiment, the difference between this embodiment and the second embodiment is that the double-rigidity reinforcement beam 5 includes four reinforcement beam bodies, and the four reinforcement beam bodies are connected end to end in a diamond shape. The two oppositely arranged tips in the double-rigidity reinforcement beam 5 are the connection parts with the outer ring 1 and the inner ring 7. One of the tips is integrally formed with the outer ring 1, and the other tip is integrally formed with the inner ring 7. The other components and connection methods are the same as those in the second embodiment.

[0026] In combination with the description of the second and third specific embodiments, the dual-rigidity reinforcement beam 5 is used to improve the axial stiffness without changing the lateral sensitivity of the elastomer, thereby reducing the thickness of the elastomer. At the same time, it can avoid the problem of excessively increasing the thickness of the parallel beam to increase the axial stiffness, and avoid excessive strain differences in the strain measurement areas of the same parallel beam 4, thereby improving the measurement sensitivity of the elastomer in the Fz, Mx and My directions.

[0027] Specific implementation method four: Combination Figure 1 This embodiment differs from the third embodiment in that the beam assembly includes an inner beam 6 and two parallel beams 4. One end of the inner beam 6 is integrally formed with the inner ring 7, and the two parallel beams 4 are oppositely arranged on either side of the other end of the inner beam 6. One end of each parallel beam 4 is integrally formed with the inner beam 6 via a flexible beam 3, and the other end of each parallel beam 4 is integrally formed with the outer ring 1. Each flexible beam 3 and its corresponding parallel beam 4 are located on the same centerline, and each flexible beam 3 is perpendicular to its corresponding inner beam 6. Other components and connection methods are the same as those of the third embodiment.

[0028] In this embodiment, by placing the parallel beam between the flexible beam and the outer ring, and placing the flexible beam on the centerline of the parallel beam, the sensor size is less affected by the size of the parallel beam, making the elastic body structure more compact. At the same time, this arrangement also reduces the distance from the flexible beam to the center of the sensor, thereby reducing the torsional deformation of the flexible beam when subjected to force, and improving the stiffness and sensitivity of the elastic body.

[0029] In this embodiment, a T-shaped groove structure is formed between the beam assembly composed of the inner beam 6 and the two parallel beams 4 and the outer ring 1. The T-shaped groove structure helps to dissipate heat from the sensor elastomer.

[0030] Specific implementation method five: Combination Figure 1 This embodiment differs from the fourth embodiment in that the strain measurement unit assembly includes a shear strain measurement unit 11 and two tension and compression strain measurement unit groups. The shear strain measurement unit 11 is mounted on top of the inner beam 6, and each tension and compression strain measurement unit group is mounted on top of a corresponding parallel beam 4. The remaining components and connection methods are the same as those in the fourth embodiment.

[0031] Specific implementation method six: Combination Figure 1 This embodiment differs from the fifth embodiment in that each tensile and compressive strain measurement unit group includes two tensile and compressive strain measurement units 10, which are symmetrically mounted at either end of the top of the parallel beam 4 along the longitudinal centerline of the corresponding parallel beam 4. The remaining components and connection methods are the same as those of the fifth embodiment.

[0032] Specific implementation method seven: Combination Figure 1 This embodiment differs from the sixth embodiment in that the shear strain measurement unit 11 on the inner beam 6 and the tensile and compressive strain measurement unit 10 on the parallel beam 4 are located in the same plane. The remaining components and connection methods are the same as those in the sixth embodiment.

[0033] With reference to the description of the fifth to seventh specific embodiments, the shear strain measurement unit 11 and the tensile and compressive strain measurement unit 10 are both arranged on the elastic body by a sputtering process. Such an arrangement is conducive to improving the arrangement accuracy and efficiency of the strain measurement units.

[0034] Specific implementation method eight: Combination Figure 1 This embodiment differs from the seventh embodiment in that six inner ring through-holes 8 are formed equidistantly along the circumference of the top of the inner ring 7. Two of the six inner ring through-holes 8 correspond to two oppositely disposed inner beams 6. The rest of the components and connection methods are the same as those of the seventh embodiment.

[0035] Specific implementation method nine: Combination Figure 1 This embodiment differs from the eighth embodiment in that eight outer ring through-holes 2 are machined circumferentially along the top of the outer ring 1. Four of the eight outer ring through-holes 2 correspond to dual-rigidity reinforcement beams 5, while the remaining four correspond to inner beams 6. The remaining components and connection methods are the same as those of the eighth embodiment.

[0036] In combination with the specific implementations eight and nine, the center point of each outer ring through hole 2 at the top of the outer ring 1 corresponding to the double rigidity reinforcement beam 5 is located on the line where the center point of the inner ring 7 and the center point of the double rigidity reinforcement beam 5 corresponding to the outer ring through hole 2 are located. The center point of each outer ring through hole 2 at the top of the outer ring 1 corresponding to the inner beam 6 is located on one side of the line where the center point of the inner ring 7 and the center point of the inner beam 6 corresponding to the outer ring through hole 2 are located. Four pin holes 9 are also processed on the top of the outer ring 1, and each pin hole 9 is arranged on the other side of the line where the center point of the inner ring 7 and the center point of an inner beam 6 are located.

[0037] Specific implementation method 10: Combination Figure 1This embodiment differs from the ninth embodiment in that the outer ring 1, inner ring 7, inner beam 6, dual-rigidity reinforcement beam 5, flexible beam 3, and parallel beam 4 are all made of aluminum alloy, stainless steel, or alloy steel. The remaining components and connection methods are the same as those of the ninth embodiment.

[0038] The present invention has been disclosed as above with reference to preferred embodiments, but this is not intended to limit the present invention. Any technician familiar with the present invention can make slight changes or modifications to equivalent embodiments using the above-disclosed structures and technical contents without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

[0039] How it works

[0040] Taking the measurement of tangential force Fx as an example: tangential force Fx is applied to the lower end face of inner ring 7. The upper end face of outer ring 1 serves as a fixed surface. The stiffness of flexible beam 3 along its length (along the X-axis) is greater than its stiffness along its thickness (along the Y-axis). Therefore, the inner beam 6, parallel beam 4, dual-rigidity reinforced beam 5, and flexible beam 3 parallel to the Fx direction are all considered rigid. The inner beam 6, parallel beam 4, dual-rigidity reinforced beam 5, and flexible beam 3 perpendicular to the Fx direction are all considered flexible. The inner beam 6 perpendicular to the Fx direction is considered a cantilever beam. This creates a strain-sensitive area on inner beam 6, forming a strain bridge, allowing Fx to be measured. Similarly, the tangential force Fy can be measured.

[0041] Taking the measurement of axial force Fz as an example: axial force Fz is applied to the lower end face of inner ring 7, with the upper end face of outer ring 1 serving as a fixed surface. Axial force Fz is transmitted to parallel beam 4 via inner beam 6. The stiffness of flexible beam 3 and dual-rigidity reinforced beam 5 along the Z-axis is greater than their stiffness along the X- and Y-axes, while the stiffness of parallel beam 4 along the X- and Y-axes is greater than its stiffness along the Z-axis. Therefore, inner beam 6, dual-rigidity reinforced beam 5, and flexible beam 3 are considered rigid, while parallel beam 4 is considered flexible. Axial force Fz is transmitted to parallel beam 4 via the four evenly distributed inner beams 6 and flexible beam 3, forming a strain-sensitive area on parallel beam 4, thus forming a strain bridge, allowing Fz to be measured.

[0042] Taking the measurement of bending moment Mx as an example: bending moment Mx is applied to the lower end face of inner ring 7, with the upper end face of outer ring 1 serving as a fixed surface, and is transmitted to parallel beam 4 via inner beam 6. The stiffness of flexible beam 3 and dual-rigidity reinforced beam 5 along the Z-axis is greater than their stiffness along the X- and Y-axes, while the stiffness of parallel beam 4 along the X- and Y-axes is greater than its stiffness along the Z-axis. Therefore, inner beam 6, dual-rigidity reinforced beam 5, and flexible beam 3 are considered rigid, while parallel beam 4 is considered flexible. Bending moment Mx is transmitted to parallel beam 4 via the four evenly distributed inner beams 6 and flexible beam 3, forming a strain-sensitive area on parallel beam 4, thus forming a strain bridge, allowing Mx to be measured. Similarly, the tangential force My can be measured.

[0043] Taking the measurement of torque Mz as an example: Torque Mz is applied to the lower end face of inner ring 7. The upper end face of outer ring 1 is fixed. The stiffness of flexible beam 3 along its length and along the Z-axis is greater than its stiffness along its thickness. The torque Mz effectively acts as a pair of equal force couples. Assuming the directions of both forces of this couple are parallel to the X-axis, the inner beam 6, parallel beam 4, and flexible beam 3, whose lengths are parallel to the X-axis, are considered rigid. The flexible beam 3, whose lengths are parallel to the Y-axis, is considered flexible. In this case, the inner beam 6 parallel to the Y-axis is considered a cantilever beam. This creates a strain-sensitive area on inner beam 6, forming a strain bridge, which allows the measurement of Mz.

Claims

1. A full-plane six-dimensional force sensor elastic body, characterized by: The elastic body comprises an outer ring (1) and an inner ring (7), the outer ring (1) being sleeved on the outer side of the inner ring (7), the outer ring (1) and the inner ring (7) being connected via four beam body assemblies, the four beam body assemblies being equidistantly arranged between the outer ring (1) and the inner ring (7) along the circumferential direction, and one end of each beam body assembly being integrally formed with the outer ring (1), and the other end of each beam body assembly being integrally formed with the inner ring (7), and a strain measuring unit assembly being installed on each beam body assembly; The elastic body further comprises four dual-rigidity reinforcement beams (5), each dual-rigidity reinforcement beam (5) being located in the middle of two adjacent beam body components, and one end of each dual-rigidity reinforcement beam (5) being integrally formed with the outer ring (1), and the other end of each dual-rigidity reinforcement beam (5) being integrally formed with the inner ring (7); The double-rigidity reinforcement beam (5) comprises four reinforcement beam bodies, which are connected end to end in a diamond-shaped arrangement. Two oppositely arranged tips of the double-rigidity reinforcement beam (5) serve as connecting portions with the outer ring (1) and the inner ring (7), one of the tips being integrally formed with the outer ring (1), and the other tip being integrally formed with the inner ring (7). The beam assembly comprises an inner beam (6) and two parallel beams (4), one end of the inner beam (6) is integrally formed with the inner ring (7), the two parallel beams (4) are relatively arranged on both sides of the other end of the inner beam (6), and one end of each parallel beam (4) is integrally formed with the inner beam (6) through a flexible beam (3), the other end of each parallel beam (4) is integrally formed with the outer ring (1), each flexible beam (3) and its corresponding parallel beam (4) are located on the same center line, and each flexible beam (3) and its corresponding inner beam (6) are arranged perpendicularly.

2. The full-plane six-dimensional force sensor elastic body according to claim 1, characterized in that: The strain measurement unit assembly comprises a shear strain measurement unit (11) and two tension and compression strain measurement unit groups. The shear strain measurement unit (11) is installed on the top of the inner beam (6), and each tension and compression strain measurement unit group is correspondingly installed on the top of a parallel beam (4).

3. The full-plane six-dimensional force sensor elastic body according to claim 2, characterized in that: Each tension and compression strain measurement unit group includes two tension and compression strain measurement units (10), and the two tension and compression strain measurement units (10) are symmetrically installed at both ends of the top of the parallel beam (4) along the center line of the length direction of the parallel beam (4).

4. The full-plane six-dimensional force sensor elastic body according to claim 3, characterized in that: The shear strain measuring unit (11) located on the inner beam (6) and the tensile and compressive strain measuring unit (10) located on the parallel beam (4) are both located in the same plane.

5. The full-plane six-dimensional force sensor elastic body according to claim 4, characterized in that: Six inner ring through holes (8) are machined at equal intervals along the circumferential direction on the top of the inner ring (7), and two of the six inner ring through holes (8) are respectively arranged to correspond to two inner beams (6) arranged opposite to each other.

6. The full-plane six-dimensional force sensor elastic body according to claim 5, characterized in that: Eight outer ring through holes (2) are machined on the top of the outer ring (1) along the circumferential direction, and four of the eight outer ring through holes (2) are respectively located in correspondence with a double-rigidity reinforcement beam (5), and the other four of the eight outer ring through holes (2) are respectively located in correspondence with an inner beam (6).

7. The full-plane six-dimensional force sensor elastic body according to claim 6, characterized in that: The outer ring (1), the inner ring (7), the inner beam (6), the double-rigidity reinforced beam (5), the flexible beam (3) and the parallel beam (4) are all made of aluminum alloy, stainless steel or alloy steel.

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