Weakly-coupled six-dimensional force sensor with flexible hinges

Abstract

A weakly-coupled six-dimensional force sensor with flexible hinges. The weakly-coupled six-dimensional force sensor comprises a force-measuring joint (3), wherein flexible hinges (2) are provided on two sides of the force-measuring joint (3) in the same direction, enabling bending deformation in all directions. Designing the anisotropic flexible hinges (2) enables bending deformation in all directions, thereby overcoming the drawbacks of difficulty in tension-compression deformation and low sensitivity of cross-shaped flexible hinges; integrated machining can be achieved, and the structure is compact; due to the fact that a single-beam structure and a double-beam structure are respectively provided in X and Y directions and are asymmetrically designed, and in order to ensure consistent ranges in all directions, the parameters of beams are in a proportional relationship, thereby achieving equal-range high-sensitivity measurement; and the two flexible hinges (2) and the force-measuring joint (3) jointly form the shape of the Chinese character "工", and each beam has a relatively large size and a high bearing capacity, is simple to machine and has no stress concentration phenomena.

Description

Weak coupling flexible hinge six-dimensional force sensor TECHNICAL FIELD

[0001] The present application relates to the technical field of six-dimensional force sensors, in particular to a weak coupling flexible hinge six-dimensional force sensor. BACKGROUND

[0002] Force sensor (also known as mechanical sensor, force sensor, etc.), is a sensor that can convert the size and even direction of the detected force signal into relevant electrical signals for information feedback. Due to the particularity of space mechanics, force sensors can be divided into one-dimensional to six-dimensional, so the complete form is a six-dimensional force sensor. The six-dimensional force sensor (also known as six-dimensional force / torque sensor, six-axis force sensor, F / T sensor) can detect the information change of six-dimensional force signals in space, i.e. three-dimensional force and three-dimensional torque, and provide accurate feedback information for high-precision motion, which is a key component of force control and motion control, and is widely used in humanoid robots, operating robots and other fields.

[0003] The force sensor is generally mainly composed of a force sensing element (i.e. a force sensing element), a conversion element and a circuit part. The force sensing element (i.e. the force sensing element), also known as an elastic body, is commonly used spring, beam, bellows, diaphragm, etc., and the materials used are mainly aluminum alloy, alloy steel and stainless steel. The conversion element is commonly used strain gauge, and the material used is various metal foils or semiconductor materials. The circuit part includes enameled wire, pcb board, etc. The main structure of the six-dimensional force sensor is basically the same, and can also be roughly divided into a loading end and a fixed end.

[0004] The mainstream product adopts a redundant design of multiple flexible hinges in parallel, 24-32 channels to measure the force of 6 dimensions, and due to the strong coupling between each degree of freedom, the overall accuracy is generally one percent of the range, which is much smaller than the accuracy of one thousandth of the range of a single force sensor. In addition, there are too many redundancies, and the calculation is large, which is difficult to use in real-time applications.

[0005] The force sensor generally uses a sheet-type flexible hinge, and the deformation mainly includes bending, stretching and torsion. Among them, stretching is related to the cross-sectional area, and is the largest in rigidity among all deformations. In order to obtain sensitive stretching, the cross-sectional area needs to be small, resulting in low strength of the sensor, small range and small overload capacity.

[0006] Torsional deformation requires a 45° angle of the strain gauge, which is difficult to paste, and is mainly used for pure torsion testing. The six-dimensional force sensor is a combination of tension, bending and torsion, and also needs to be combined with other tension and bending sensors, which has a complex structure.

[0007] The prior art proposes an orthogonal flexible hinge scheme, which greatly reduces the coupling degree between the degrees of freedom, still needs seven groups of bending deformation to achieve, and has a complex structure. Therefore, the present application proposes a weak coupling flexible hinge six-dimensional force sensor.

[0008] SUMMARY

[0009] The application aims at the orthogonal flexible hinge pointed out in the background art, greatly reduces the coupling degree between the degrees of freedom, still needs seven groups of bending deformation to realize, and proposes a weak coupling flexible hinge six-dimensional force sensor.

[0010] The technical scheme of the application is a weak coupling flexible hinge six-dimensional force sensor, comprising a force measuring joint, and flexible hinges are arranged on the same side of the force measuring joint, so that bending deformation can be generated in each direction.

[0011] Preferably, the flexible hinge comprises an X-direction flexible hinge and a Y-direction flexible hinge, and the X-direction flexible hinge is perpendicular to the middle part of the Y-direction flexible hinge.

[0012] Preferably, the two groups of flexible hinges and the force measuring joint together form an I-shaped structure.

[0013] Preferably, two groups of strain gauges are mounted on the two groups of X-direction flexible hinges, and four groups of strain gauges are mounted on the two groups of Y-direction flexible hinges.

[0014] Preferably, the two sides of the two groups of flexible hinges are respectively connected with mounting blocks for fixing the sensor base.

[0015] Compared with the prior art, the application has the following beneficial technical effects:

[0016] The application designs anisotropic flexible hinges, bending deformation can be generated in each direction, and overcomes the disadvantages of difficulty in tensile and compressive deformation and low sensitivity of the cross-shaped flexible hinge; the flexible hinge can be integrally processed and has a compact structure.

[0017] Since the X and Y are single-beam and double-beam structures respectively, the design is asymmetric, in order to ensure that the ranges in each direction are consistent, the parameters of the beams are in proportional relationship, and equal-range high-sensitivity measurement is realized.

[0018] In the application, the two groups of flexible hinges and the force measuring joint together form an I-shaped structure, the size of each beam is large, the bearing capacity is strong, the processing is simple, and there is no stress concentration phenomenon. BRIEF DESCRIPTION OF DRAWINGS

[0019] Fig. 1 is a perspective view of a weak coupling flexible hinge six-dimensional force sensor;

[0020] Fig. 2 is a structural schematic view of the flexible hinge in the application.

[0021] Fig. 1 is a perspective view of a weak coupling flexible hinge six-dimensional force sensor; DETAILED DESCRIPTION

[0022] The technical solutions of the present application will be further described in detail below in combination with the drawings and specific embodiments.

[0023] The components of the embodiments of the present application generally described and shown in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but merely represents selected embodiments of the present application.

[0024] Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present application.

[0025] In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "two ends", "one end", "the other end" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0026] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0027] Embodiments

[0028] As shown in FIGS. 1-2, the weak coupling flexible hinge six-dimensional force sensor provided by the present application comprises a force measuring joint 3, a rigid block is embedded in the inside of the force measuring joint 3, and flexible hinges 2 are fixedly connected to the same side of the force measuring joint 3, the flexible hinges 2 comprise Y-direction flexible hinges 21 and X-direction flexible hinges 22, the X-direction flexible hinges 22 are perpendicular to the middle part of the Y-direction flexible hinges 21, and the two groups of flexible hinges 2 and the force measuring joint 3 together form an I-shaped type, so that bending deformation can be generated in each direction, overcoming the disadvantages of low sensitivity and difficulty in tensile and compressive deformation of the cross flexible hinge. The two sides of the two groups of flexible hinges 2 are respectively connected with mounting blocks 1, the mounting blocks 1 are arc-shaped structures, and are used for fixing the sensor base.

[0029] The upper and lower surfaces and the front and rear surfaces of the two groups of Y-direction flexible hinges 21 are respectively provided with strain gauges 4, and the upper and lower surfaces and the left and right surfaces of the two groups of X-direction flexible hinges 22 are respectively provided with a group of strain gauges 4. There are six groups of strain gauges, each group of two directions forms a full-bridge strain gauge, four groups are arranged on the upper and lower surfaces and the front and rear surfaces of the two groups of Y-direction flexible hinges 21, one group is arranged on the upper and lower surfaces of the two groups of X-direction flexible hinges 22, and one group is arranged on the left and right surfaces of the two groups of X-direction flexible hinges 22; the six groups of strain gauges correspond to the six-dimensional sensor, and there is no redundant degree of freedom.

[0030] In the present application, the X-direction deformation beam and the Y-direction deformation beam are provided, the X-direction deformation beam is composed of two groups of X-direction flexible hinges 22, and the force measuring joint 3 is embedded in the middle of the X-direction deformation beam, and the Y-direction deformation beam is composed of two groups of Y-direction flexible hinges 21. Since the X and Y directions are single-beam and double-beam structures respectively, the single-beam corresponds to the force measuring joint 3, and the double-beam corresponds to the outer edge of the two flexible hinges 2, in order to ensure that the range of each direction is consistent, the parameters of the beam are in proportional relationship, and equal-range high-sensitivity measurement is realized.

[0031] Specifically, according to the bending inertia moment I proportional to wt^3 / L^3, w is the width, t is the thickness, and L is the length, in the present application, X and Y adopt single-beam and double-beam parallel forms respectively, in order to ensure that the range is consistent, the bending stiffness of the single-beam satisfies the sum of the bending stiffness of the two beams. For example, when the cross section w*t is the same, the length of the two beams needs to be twice that of the single beam , and the bending stiffness obtained is consistent. Since X and Y are one beam and two beams respectively, the anisotropic beam is provided, the size of each beam is large, the bearing capacity is strong, the processing is simple, there is no stress concentration phenomenon, and the six-dimensional sensor can be composed of three or more evenly distributed redundant modes.

[0032] The above specific embodiments are only preferred embodiments of the present application, based on the technical solutions of the present application and the related inspirations of the above embodiments, those skilled in the art can make various alternative improvements and combinations on the above specific embodiments; the above specific embodiments are only an explanation of the present application, and it is not a limitation of the present application.

Claims

1. A weakly coupled flexible hinge six-dimensional force sensor, characterized in that: The force measuring joint comprises a force measuring joint, and flexible hinges are arranged on both sides of the force measuring joint in the same direction, so that bending deformation can be generated in all directions.

2. A weakly coupled flexible hinge six-axis force sensor according to claim 1, characterized in that: The flexible hinge includes an X-direction flexible hinge and a Y-direction flexible hinge, and the X-direction flexible hinge is perpendicular to the middle of the Y-direction flexible hinge.

3. A weakly coupled flexible hinge six-dimensional force sensor according to claim 2, characterized in that: The two groups of flexible hinges and the force measuring joint together form an I-shape.

4. A weakly coupled flexible hinge six-dimensional force sensor according to claim 3, characterized in that: Two sets of strain gauges are installed on the two sets of X-direction flexible hinges, and four sets of strain gauges are installed on the two sets of Y-direction flexible hinges.

5. The weakly coupled flexible hinge six-dimensional force sensor according to claim 1, characterized in that: Both sides of the two groups of flexible hinges are respectively connected with mounting blocks for fixing the sensor base.

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