Weak coupling flexible hinge six-dimensional force sensor

Abstract

The utility model relates to the technical field of six-dimensional force sensors, in particular to a weak coupling flexible hinge six-dimensional force sensor. According to the technical scheme, the weak coupling flexible hinge six-dimensional force sensor comprises a force measuring connector, and flexible hinges are arranged on the two sides of the force measuring connector in the same direction, so that bending deformation can be generated in all directions. The anisotropic flexible hinge is designed, bending deformation can be generated in all directions, and the defects that a cross-shaped flexible hinge is difficult in tension and compression deformation and low in sensitivity are overcome; integrated machining can be achieved, and the structure is compact; as XY is of a single-beam structure and a double-beam structure respectively and is asymmetrically designed, in order to ensure that ranges in all directions are consistent, parameters of the beams are in proportional relation, and equal-range high-sensitivity measurement is realized; and the two groups of flexible hinges and the force measuring joints jointly form an I shape, and each beam is large in size, high in bearing capacity, simple to process and free of stress concentration.

Description

Technical Field

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

[0002] Force sensors (also called mechanical sensors, force sensors, etc.) are sensors that can convert the size and even direction of detected force signals into relevant electrical signals for information feedback. Due to the particularity of spatial mechanics, force sensors can be divided into one to six dimensions, so their complete form is a six-dimensional force sensor. Six-dimensional force sensors (also called six-dimensional force / torque sensors, six-axis force sensors, F / T sensors) can simultaneously detect the information changes of six-dimensional force signals in space, namely three-dimensional force and three-dimensional torque, and provide accurate feedback information for high-precision movements. They are key components for force control and motion control and are widely used in humanoid robots, operating robots and other fields.

[0003] Force sensors are generally composed of force-sensitive elements (i.e. force-sensing elements), conversion elements, and circuit parts. Force-sensitive elements (i.e. force-sensing elements), also known as elastic bodies, are commonly made of springs, beams, bellows, diaphragms, etc., and the materials used are mostly aluminum alloys, alloy steels, and stainless steel. Conversion elements are commonly made of strain gauges, and the materials used are various metal foils or semiconductor materials. The circuit part includes enameled wires, PCB boards, etc. The main structure of the six-dimensional force sensor is generally the same, and can also be roughly divided into the loading end and the fixed end.

[0004] Mainstream products use a redundant design with multiple flexible hinges in parallel, with 24-32 channels to measure the force in six dimensions. Due to the strong coupling between the degrees of freedom, the overall accuracy is generally 1% of the range, which is much less than the accuracy of 1 / 1000 of the range of a single force sensor. In addition, there is too much redundancy and a large amount of calculation, making it difficult to use in situations where real-time requirements are high.

[0005] Among force sensors, sheet-type flexible hinges are commonly used, and deformations mainly include bending, stretching and torsion. Among them, stretching is related to the cross section and has the greatest stiffness among all deformations. In order to obtain sensitive stretching, the cross-sectional area needs to be very small, resulting in low sensor strength, small range, and small overload capacity.

[0006] Torsion deformation requires strain gauges to be attached at a 45° angle, which is difficult and is mainly used for pure torsion testing. The six-dimensional force sensor is a combination of tension, bending and twisting, and must be coordinated with other tension and bending sensors, so the structure is complex.

[0007] Prior art has proposed an orthogonal flexible hinge solution, which greatly reduces the coupling degree between degrees of freedom, but still requires seven sets of bending deformations to achieve, and the structure is complex. To this end, the present application proposes a weakly coupled flexible hinge six-dimensional force sensor. Summary of the invention

[0008] The purpose of this application is to propose a weakly coupled flexible hinge six-dimensional force sensor in response to the problem that the orthogonal flexible hinge pointed out in the background technology greatly reduces the coupling degree between the degrees of freedom, but still requires seven sets of bending deformations to be realized and has a complex structure.

[0009] The technical solution of the present application: a weakly coupled flexible hinge six-dimensional force sensor, comprising a force measuring joint, wherein flexible hinges are arranged on both sides of the force measuring joint in the same direction so that bending deformation can occur in all directions.

[0010] 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 of the Y-direction flexible hinge.

[0011] Preferably, the two groups of flexible hinges and the force measuring joint together form an I-shape.

[0012] Preferably, two groups of strain gauges are installed on the two groups of X-direction flexible hinges, and four groups of strain gauges are installed on the two groups of Y-direction flexible hinges.

[0013] Preferably, both sides of the two groups of flexible hinges are respectively commonly connected with mounting blocks for fixing the sensor base.

[0014] Compared with the prior art, this application has the following beneficial technical effects:

[0015] The present application designs an anisotropic flexible hinge, which can produce bending deformation in all directions, overcoming the drawbacks of the cross flexible hinge that is difficult to deform by tension and compression and has low sensitivity; it can be processed in an integrated manner and has a compact structure;

[0016] Since XY is a single beam and double beam structure with asymmetric design, in order to ensure the same range in each direction, the parameters of the beams are proportional to achieve equal range and high sensitivity measurement;

[0017] The two groups of flexible hinges and force measuring joints in the present application together form an I-shape, and each beam has a large size, a strong bearing capacity, simple processing, and no stress concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a stereogram of a weakly coupled flexible hinge six-dimensional force sensor;

[0019] Figure 2 It is a structural schematic diagram of the flexible hinge in this application.

[0020] Figure numerals: 1, mounting block; 2, flexible hinge; 21, Y-axis flexible hinge; 22, X-axis flexible hinge; 3, force measuring joint; 4, strain gauge. DETAILED DESCRIPTION

[0021] The technical solution of the present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0022] The components of the embodiments of the present application generally described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed, but merely represents the selected embodiments of the present application.

[0023] Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of this application.

[0024] 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 positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention 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 operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0025] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0026] Example

[0027] like Figure 1-2 As shown, a weakly coupled flexible hinge six-dimensional force sensor proposed in the present application includes a force measuring joint 3, a rigid block is embedded inside the force measuring joint 3, and flexible hinges 2 are fixedly connected to both sides of the force measuring joint 3 in the same direction. The flexible hinge 2 includes a Y-direction flexible hinge 21 and an X-direction flexible hinge 22, and the X-direction flexible hinge 22 is perpendicular to the middle of the Y-direction flexible hinge 21. The two groups of flexible hinges 2 and the force measuring joint 3 together form an I-shaped shape, so that bending deformation can occur in all directions, overcoming the drawbacks of the cross flexible hinge's difficulty in tensile and compressive deformation and low sensitivity. The two sides of the two groups of flexible hinges 2 are respectively connected to a mounting block 1, and the mounting block 1 is an arc-shaped structure for fixing the sensor base.

[0028] Among them, strain gauges 4 are installed on the upper and lower surfaces and the front and rear surfaces of the two groups of Y-direction flexible hinges 21, and one group of strain gauges 4 is installed on the upper and lower surfaces and the left and right surfaces of the two groups of X-direction flexible hinges 22. There are six groups of strain gauges in total, and each group of two directions constitutes a full-bridge strain gauge. Four groups are installed 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 installed on the upper and lower surfaces of the two groups of X-direction flexible hinges 22, and one group is installed on the left and right surfaces of the two groups of X-direction flexible hinges 22; the six groups of strain gauges just correspond to the six-dimensional sensor, without redundant degrees of freedom.

[0029] In the present application, an X-direction deformation beam and a 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 the consistency of the range in each direction, the parameters of the beam are proportional to achieve equal range high sensitivity measurement.

[0030] Specifically, according to the bending inertia I being proportional to wt^3 / L^3, w is the width, t is the thickness, and L is the length, in this application, X and Y are respectively in the form of a single beam and two beams in parallel. In order to ensure the same range, the above parameters satisfy the bending stiffness of a single beam and the sum of the two beams. For example, when the cross-section w*t is the same, the length of the two beams needs to be a single beam. Since X and Y are one beam and two beams respectively, the setting of anisotropic beams makes each beam larger in size, with strong bearing capacity, simple processing, and no stress concentration. It can also be evenly distributed in three or more numbers to form a six-dimensional sensor in a redundant manner.

[0031] The above-mentioned specific embodiments are merely preferred embodiments of the present application. Based on the technical solutions of the present application and the relevant inspirations of the above-mentioned embodiments, those skilled in the art may make various alternative improvements and combinations to the above-mentioned specific embodiments. The above-mentioned specific embodiments are merely explanations of the present application, and they are not limitations of the present application.

Claims

1. A weakly coupled flexible hinge six-dimensional force sensor, characterized in that: It includes 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; 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; the two sides of the two groups of flexible hinges are respectively connected with mounting blocks for fixing the sensor base.

2. A weakly coupled flexible hinge six-dimensional force sensor according to claim 1, characterized in that: The two groups of flexible hinges and the force measuring joint together form an I-shape.

3. A weakly coupled flexible hinge six-dimensional force sensor according to claim 2, characterized in that: Two groups of strain gauges are installed on the two groups of X-direction flexible hinges, and four groups of strain gauges are installed on the two groups of Y-direction flexible hinges.

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