Torque sensor module

Abstract

The present invention provides a torque sensor module that can simultaneously increase sensitivity and rigidity as a torque sensor module to be mounted on a robot arm or the like for sensing z-axis torque (Tz). The torque sensor module of the present invention includes a body in which a first sensitivity adjustment hole, a strain measurement hole, a second sensitivity adjustment hole, and a rigidity adjustment hole are repeatedly formed along the circumferential direction between a central hole and an outer circumferential surface; and a pair of strain gauges attached one to each side wall surface of the strain measurement hole, wherein the centers of the first sensitivity adjustment hole, the second sensitivity adjustment hole, and the rigidity adjustment hole are located at the same first distance from the center of the body, and the strain measurement hole is trapezoidal in shape with the central side having a longer length than the outer circumferential side, and at least a portion of the area of ​​the trapezoidal shape can be arranged so as to be crossed by an arc of the first distance.

Description

Technical Field

[0001] The present invention relates to a torque sensor module, and more particularly, to a torque sensor module that can structurally enhance sensitivity and rigidity compared to the prior art.

Background Art

[0002] In the case of industrial robots, generally, a torque sensor in a form that can be mounted on a robot wrist or the like is used to measure the force applied by a mechanism mounted on the robot arm to the work object. The method of mounting a torque sensor on a robot joint for measurement has complex dynamic analysis and errors may accumulate, and it has been studied more in the field of intelligent service robots in recent years than in industrial robots.

[0003] When a robot arm or other part collides with an external object or person, it is impossible to detect such a collision, and there is a problem that it is difficult to ensure safety through active countermeasures. Since most current intelligent robots are not well-known and need to perform operations in an unmanaged environment, the safety of the robot and people should be given even higher priority than industrial robots and the robot should operate accordingly. For example, despite the influence of crosstalk such as the force (Bending Force) when a person pushes or collides, in the robot arm, there are cases where it is necessary to precisely control by sensing the rotational force on the xy plane in the rectangular coordinate system, that is, the z-axis torque (Tz).

[0004] As related prior art documents, Patent Application No. 10-2009-0115343 (Nov. 26, 2009), etc. can be referred to. However, existing torque sensor modules mounted on robot arms or the like for sensing such z-axis torque (Tz) have a trade-off relationship between sensitivity and rigidity. Such conventional torque sensor modules have a problem that it is difficult to optimize rigidity and sensitivity by attaching a strain gauge to a spoke 300, which is a connecting part that supports such rigidity, and there are limitations in performance. [Prior art documents] [Patent Documents]

[0005] Korean Patent Application No. 10-2009-0115343 [Overview of the project] [Problems that the invention aims to solve]

[0006] Therefore, the present invention was derived to solve the above-mentioned problems, and the object of the present invention is to provide a torque sensor module that can simultaneously increase sensitivity and rigidity as a torque sensor module to be attached to a robot arm or the like for sensing z-axis torque (Tz).

[0007] Other objects of the present invention will become more clear based on the preferred embodiments described below. [Means for solving the problem]

[0008] First, to summarize the features of the present invention, a torque sensor module according to one aspect of the present invention for achieving the above objectives includes: a body having a first sensitivity adjustment hole, a strain measurement hole, a second sensitivity adjustment hole, and a stiffness adjustment hole repeatedly formed between a central hole and an outer circumferential surface along the circumferential direction; and a pair of strain gauges attached one to each side wall surface of the strain measurement hole, wherein the centers of the first sensitivity adjustment hole, the second sensitivity adjustment hole, and the stiffness adjustment hole are located at the same first distance from the center of the body, and the strain measurement hole is trapezoidal in shape with the central side having a longer length than the outer circumferential side, and at least a portion of the area of ​​the trapezoidal shape can be arranged so as to be traversed by an arc of the first distance.

[0009] The first sensitivity adjustment hole and the second sensitivity adjustment hole may have the same shape.

[0010] Alternatively, the stiffness adjustment holes may be multiple in number, and the multiple stiffness adjustment holes may have the same shape as the first sensitivity adjustment hole and the second sensitivity adjustment hole.

[0011] Alternatively, the stiffness adjustment holes may be multiple in number, and the multiple stiffness adjustment holes may have different shapes from the first sensitivity adjustment hole and the second sensitivity adjustment hole.

[0012] The stiffness adjustment holes are numerous, and the numerous stiffness adjustment holes may include two or more different shapes.

[0013] The size of the rigidity adjustment hole may be the same as the size of the first sensitivity adjustment hole and the second sensitivity adjustment hole.

[0014] The size of the rigidity adjustment hole is preferably larger than the size of the first sensitivity adjustment hole and the second sensitivity adjustment hole.

[0015] The torque sensor module further includes a circuit board connected to signal lines from each strain gauge of a pair of strain gauges mounted at each of the plurality of strain measurement holes, the circuit board digitally processes the strain sensing signals from the signal lines to calculate a torque value for each of the strain measurement holes, and can use the torque values ​​to calculate a torque value for a predetermined single axis without the influence of cross torque. [Effects of the Invention]

[0016] The torque sensor module according to the present invention increases rigidity, reducing displacement due to external forces (crosstalk), enabling the measurement of the pure torque to be measured, and improves sensitivity, thereby enhancing the accuracy and resolution of the strain sensor operation. Conventional torque sensor modules have limitations in performance because the strain gauges are attached to the spoke portion that supports such rigidity, making it difficult to optimize rigidity and sensitivity.

[0017] Thus, by attaching the torque sensor module of the present invention, which possesses both sensitivity and rigidity, to a robot arm, it becomes possible to provide precise sensor information from strain gauges, thereby realizing high performance. For example, it can also assist in precisely controlling rotational force in the xy plane, i.e., z-axis torque (Tz), despite the effects of crosstalk, such as a force applied by a person (z-axis bending force). [Brief explanation of the drawing]

[0018] The accompanying drawings, included as part of the detailed description to aid in understanding the present invention, provide embodiments of the invention and illustrate the technical idea of ​​the invention together with the detailed description. [Figure 1] This is a schematic perspective view of a torque sensor module according to one embodiment of the present invention. [Figure 2] Figure 1 is a front view of the torque sensor module. [Figure 3] This is a front view of a torque sensor module according to another embodiment of the present invention. [Figure 4] This is a front view of a torque sensor module according to yet another embodiment of the present invention. [Figure 5] This is a front view of a torque sensor module according to yet another embodiment of the present invention. [Figure 6] This is an example of a torque calculation circuit using strain gauges according to the present invention. [Modes for carrying out the invention]

[0019] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. At this time, the same components in each drawing are denoted by the same reference numerals as much as possible. Note that detailed descriptions of functions and / or configurations that are already known are omitted. The content disclosed below focuses on the parts necessary for understanding the operations according to various embodiments, and descriptions of elements that may obscure the gist of the description are omitted. Further, some components in the drawings may be shown exaggeratedly, omitted, or schematically. The size of each component does not fully reflect the actual size, and thus, the content described herein is not limited by the relative sizes or intervals of the components depicted in each drawing.

[0020] In describing embodiments of the present invention, if it is determined that a specific description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof is omitted. And the terms described below are terms defined in consideration of the functions in the present invention, and these may vary depending on the intention or convention of the user, operator, etc. Therefore, the definition should be made based on the content throughout this specification. The terms used in the detailed description are merely for explaining the embodiments of the present invention and should never be limiting. Unless otherwise specified, singular expressions include the meaning of plural forms. In this specification, expressions such as "including" or "comprising" are for referring to specific characteristics, numbers, steps, operations, elements, some of them or combinations thereof, and should not be construed as excluding the existence or possibility of one or more other characteristics, numbers, steps, operations, elements, some of them or combinations thereof in addition to those described.

[0021] Furthermore, terms such as first, second, etc. can be used to describe various components, but the components are not limited by the terms, and the terms are used only for the purpose of distinguishing one component from another.

[0022] FIG. 1 is a schematic perspective view of a torque sensor module 100 according to an embodiment of the present invention.

[0023] Figure 2 is a front view of the torque sensor module 100 shown in Figure 1.

[0024] Referring to Figures 1 and 2, a torque sensor module 100 according to one embodiment of the present invention may include a circular body 110 having a predetermined thickness, a pair of strain gauges 121 and 122 mounted in each of the multiple strain measurement holes 112 of the body 110, and a circuit board 130 connected to signal lines from each of the strain gauges 121 and 122 of the multiple strain gauge pairs 120.

[0025] The circuit board 130 is manufactured in the form of a ring-shaped PCB (Printed Circuit Board) as illustrated in the drawing, and can be mounted on either side of the body 110. The circuit board 130 is manufactured so that no part of it gets caught in the portion that crosses the central hole 119 of the body 110, and can be mounted on a predetermined axis on a Cartesian coordinate system (e.g., xyz), i.e., on the arm of a robot or the like that is intended to sense and control z-axis torque (Tz), via the central hole 119 of the body 110. The circuit board 130 can be equipped with circuit components such as an amplifier for digitally processing the sensing signals from the signal lines of each strain gauge 121, 122 to calculate torque values, an AD (Analog to Digital) converter, and a calculation unit.

[0026] In the torque sensor module 100 of the present invention, the rigidity of the body 110 is increased to reduce displacement due to external force (crosstalk), enabling the measurement of the pure torque to be measured, and the sensitivity is increased to improve the accuracy and resolution of the strain sensor operation. Conventional torque sensor modules have limitations in performance because it is difficult to optimize rigidity and sensitivity in such modules due to the attachment of strain gauges to the spoke portion that supports the rigidity.

[0027] Thus, by attaching the torque sensor module 100 of the present invention, which possesses both sensitivity and rigidity, to a robot arm, it becomes possible to precisely provide sensor information from strain gauges 121 and 122, thereby realizing high performance. For example, it can also assist in precisely controlling rotational force in the xy plane, i.e., z-axis torque (Tz), despite the effects of crosstalk, such as a force applied by a person (z-axis bending force).

[0028] For this purpose, as shown in Figures 1 and 2, the body 110 includes a first sensitivity adjustment hole 111, a strain measurement hole 112, a second sensitivity adjustment hole 113, and a stiffness adjustment hole 114 along the circumferential direction between the central hole 119 and the outer circumferential surface, and the first sensitivity adjustment hole 111, strain measurement hole 112, second sensitivity adjustment hole 113, and stiffness adjustment hole 114 are formed in sequence two or more times.

[0029] The rigidity adjustment holes 114 are formed one or more times between the second sensitivity adjustment hole 113 and the first sensitivity adjustment hole 111, and can be formed in an appropriate number so as to appropriately reduce the overall weight while maintaining the rigidity of the sensor module 100.

[0030] A first sensitivity adjustment hole 111 and a second sensitivity adjustment hole 113 are formed on both sides of the strain measurement hole 112 in the circumferential direction, at positions separated by a predetermined distance from the strain measurement hole 112. Multiple stiffness adjustment holes 114 can be formed at positions spaced apart with a predetermined pitch in the circumferential direction. The holes at both ends of the stiffness adjustment holes 114 can also be formed to be separated by a predetermined distance from each of the first sensitivity adjustment holes 111 or the second sensitivity adjustment holes 113.

[0031] The strain measurement hole 112 is a hole for mounting strain gauges 121 and 122 for measuring the strain applied to the torque sensor module 100 at the position where the torque sensor module 100 is installed. As shown in the figure, a pair of strain gauges 120 are mounted one on each side wall of the strain measurement hole 112, that is, on both side walls in the circumferential direction, facing each other.

[0032] Preferably, the first sensitivity adjustment holes 111 and the second sensitivity adjustment holes 113, which are symmetrically formed one on each side of the strain measurement hole 112, are formed at predetermined distances from the strain measurement hole 112 in the circumferential direction, and are formed to an appropriate size so that the strain gauges 121 and 122 can generate a sensing signal that measures an appropriate deformation rate at that position.

[0033] In addition, it is advantageous for measuring the deformation rate of the strain gauges 121 and 122 if the strain measurement hole 112 is formed in a trapezoidal shape, with the central side having a longer length than the outer peripheral side. The sensitivity of the strain gauges 121 and 122 may vary depending on their position, the distance from the first sensitivity adjustment hole 111 and the second sensitivity adjustment hole 113, and the size of the hole. Therefore, the distance from the first sensitivity adjustment hole 111 and the second sensitivity adjustment hole 113, and the size of the hole should be formed to an appropriate distance and size according to the purpose, and it is preferable that the inclination of the circumferential side walls of the trapezoid to which the strain gauges 121 and 122 are attached is also formed to have an appropriate symmetrical inclination. For example, it is preferable that the angle θ between the extension of the line segment connecting the center of the trapezoid and the center O of the torque sensor module 100 and the respective extensions of the side walls of the trapezoid is 50 degrees or less (θ is greater than 0).

[0034] Although the first sensitivity adjustment hole 111, the second sensitivity adjustment hole 113, and the rigidity adjustment hole 114 are shown as circular in example form, they are not limited to this and can be formed in a variety of shapes, such as circles, ellipses, trapezoids, triangles, squares, pentagons, and other polygons.

[0035] Multiple stiffness adjustment holes 114 can be formed at positions spaced apart so as to have a predetermined pitch in the circumferential direction. The number of stiffness adjustment holes 114 can be formed in an appropriate number between the second sensitivity adjustment hole 113 and the first sensitivity adjustment hole 111, with an appropriate size and spacing distance so as to maintain a predetermined level of stiffness. In a previous related prior art document, Japanese Patent Application No. 10-2009-0115343 (November 26, 2009), the structure could not guarantee stiffness and sensitivity because the gauge was attached to the spoke 300. However, the stiffness adjustment holes 114 of the present invention are not in the form of spokes, but are holes formed on a surface that extends to the outer circumferential surface of the body 110 itself. Therefore, the stiffness can be increased to maintain the shape of the torque sensor module 100 better than in the form of spokes.

[0036] Furthermore, as shown in Figures 1 and 2, it is preferable that the centers of the first sensitivity adjustment hole 111, the second sensitivity adjustment hole 113, and the rigidity adjustment hole 114 are positioned on the same first distance r1 from the center O of the body 110. This allows for the provision of deformation rate sensor information for deformation from any direction in a well-balanced manner.

[0037] The trapezoidal strain measurement holes 112 may be formed such that their centers lie on the same first distance r1 from the center O, i.e., on the same arc relative to the center O, as with the first sensitivity adjustment hole 111, the second sensitivity adjustment hole 113, and the stiffness adjustment hole 114. However, the strain measurement holes 112 may be arranged such that at least a portion of the area (the inner space of the hole), excluding the four sides of the trapezoidal shape, crosses the arc relative to the center O at the first distance r1.

[0038] Furthermore, the sensitivity of the strain gauges 121 and 122 can vary depending on where they are positioned on the side walls of the strain measurement hole 112. For example, if the trapezoidal strain measurement hole 112 is formed such that its center lies on the same first distance r1 from the center O, i.e., on the same arc relative to the center O, as is the case with the first sensitivity adjustment hole 111, the second sensitivity adjustment hole 113, and the stiffness adjustment hole 114, then the strain gauges 121 and 122 may have their bottom centers lies on the same first distance r1 from the center O. However, it is preferable that the strain gauges 121 and 122 are positioned such that the centers of their bottoms are located within the trapezoidal hole at a distance less than the first distance r1.

[0039] In Figures 1 and 2, the stiffness adjustment holes 114 can be formed in an appropriate number to appropriately reduce the overall weight while maintaining the stiffness of the torque sensor module 100. Furthermore, an appropriate number of holes 150 can be formed on an extra surface of the body 110 at another second distance r2 from the center O to further reduce the weight, and an appropriate number of holes 160 can be further formed on an extra surface of the body 110 at yet another third distance r3 from the center O. Such holes 111, 112, 113, 114, 150, and 160 can also be used to install cables for connection to the circuit board 130 and cables and components for connection to other accessories that make up the robot.

[0040] Figure 3 is a front view of a torque sensor module 200 according to another embodiment of the present invention.

[0041] Referring to Figure 3, in another embodiment of the present invention, the torque sensor module 200 can have the first sensitivity adjustment hole 111 and the second sensitivity adjustment hole 113 formed in the same shape (for example, circular), as shown in Figures 1 and 2, and the multiple rigidity adjustment holes 114 can also be formed in the same shape (for example, circular) as the first sensitivity adjustment hole 111 and the second sensitivity adjustment hole 113.

[0042] However, while Figures 1 and 2 illustrate that the diameter of the rigidity adjustment hole 114 is the same as the diameter of the first sensitivity adjustment hole 111 and the second sensitivity adjustment hole 113, the design is not limited to this. The diameter of the rigidity adjustment hole 114 may be smaller than the diameter of the first sensitivity adjustment hole 111 and the second sensitivity adjustment hole 113. Preferably, as shown in Figure 3, a diameter larger than the diameter of the first sensitivity adjustment hole 111 and the second sensitivity adjustment hole 113 is advantageous when considering the weight of the sensor module.

[0043] Figure 4 is a front view of a torque sensor module 300 according to yet another embodiment of the present invention.

[0044] Referring to Figure 4, in yet another embodiment of the present invention, the torque sensor module 300, as shown in Figures 1 and 2, can have the first sensitivity adjustment hole 111 and the second sensitivity adjustment hole 113 formed in the same shape (e.g., circular), and the multiple rigidity adjustment holes 114 can also be formed in the same shape (e.g., circular) as the first sensitivity adjustment hole 114 and the second sensitivity adjustment hole 113.

[0045] However, in this example, the (diameter) size of the first sensitivity adjustment hole 111 and the second sensitivity adjustment hole 113 are the same as in Figure 3, but the (diameter) size of the rigidity adjustment hole 114 is larger than in Figure 3. This reduces the number of rigidity adjustment holes 114, which may be advantageous in reducing the overall weight of the sensor module depending on the purpose.

[0046] Figure 5 is a front view of a torque sensor module 400 according to yet another embodiment of the present invention.

[0047] Referring to Figure 5, in yet another embodiment of the present invention, the torque sensor module 400 may have the first sensitivity adjustment hole 111 and the second sensitivity adjustment hole 113 formed in the same shape (for example, circular), and the multiple rigidity adjustment holes 114 may be formed in a different shape (for example, elliptical) from the first sensitivity adjustment hole 111 and the second sensitivity adjustment hole 113.

[0048] In this case as well, it is preferable that the (diameter) sizes of the first sensitivity adjustment hole 111 and the second sensitivity adjustment hole 113 are the same, and although it has been illustrated that the size of the rigidity adjustment hole 114 is larger than the (diameter) sizes of the first sensitivity adjustment hole 111 and the second sensitivity adjustment hole 113, it is not ruled out that in some cases, the size of the rigidity adjustment hole 114 may be the same as or smaller than the size of the first sensitivity adjustment hole 111 and the second sensitivity adjustment hole 113, from the viewpoint of the passage area of ​​the hole.

[0049] In addition to these embodiments, the multiple rigidity adjustment holes 114 may be formed to include two or more different shapes (combinations of circular, elliptical, trapezoidal, triangular, quadrilateral, and pentagonal polygons are possible), in which case the first sensitivity adjustment hole 111 and the second sensitivity adjustment hole 113 can also be made up of various shapes other than circular, such as elliptical, trapezoidal, triangular, quadrilateral, and pentagonal polygons.

[0050] Figure 6 shows an example of a torque calculation circuit using the strain gauge of the present invention.

[0051] Referring to Figure 6, the circuit board 130 is connected to the signal lines of each strain gauge 121, 122 and may include a torque calculation circuit that includes an amplifier (Amp), an analog-to-digital (ADC), and a calculation unit for calculating torque values, etc.

[0052] The amplifier (Amp) amplifies the output signal of the Wheatstone bridge, which is the sensing signal of the strain gauges 121 and 122 included in the Wheatstone bridge circuit. The AD converter (ADC) converts the amplified signal into a digital value. The calculation unit can calculate the torque value for the attachment position of the strain gauges 121 and 122 based on the digital value.

[0053] In this way, the circuit board 130 can digitally process the strain sensing signals from the signal lines of each strain gauge 121, 122 to calculate the torque value for each strain measurement hole 112. Furthermore, it can use the torque value to calculate the torque value (Tz) for a predetermined axis without the influence of crosstalk, and this can be used for controlling robots and the like. In a torque sensor module, when measuring the torque components necessary for control, forces and torque components from other axes will affect the output of the torque sensor module's torque value. This phenomenon in which undesirable forces and torque components affect the output of the torque sensor module's torque value is called crosstalk (mutual interference or external force).

[0054] As shown in Figure 6, a Wheatstone bridge circuit is constructed that includes appropriate selections of resistors R, R, and G, and elements of strain gauges 121 and 122. The method for calculating the torque value from the sensing signals for the deformation rate of each strain gauge 121 and 122 is well known, so a detailed explanation is omitted here. For the calculation of the torque value, you can refer to relevant prior art such as Japanese Patent Application No. 10-2009-0115343 (November 26, 2009).

[0055] As described above, the torque sensor modules 100, 200, 300, and 400 according to the present invention increase rigidity, reducing displacement due to external forces (crosstalk), enabling the measurement of the pure torque to be measured, and improve the accuracy and resolution of strain sensor operation by increasing sensitivity. Conventional torque sensor modules have limitations in performance because it is difficult to optimize rigidity and sensitivity due to the strain gauge being attached to the spoke portion that supports such rigidity. Thus, by attaching the torque sensor modules 100, 200, 300, and 400 of the present invention, which have both sensitivity and rigidity, to a robot arm, it becomes possible to provide precise sensor information from the strain gauge, realizing high performance. For example, it can also assist in precisely controlling rotational force in the xy plane, i.e., z-axis torque (Tz), despite the influence of crosstalk such as a force pushed or struck by a person (z-axis bending force).

[0056] Although the present invention has been described above with specific details such as concrete components, limited embodiments, and drawings, these are provided only to aid in a more general understanding of the present invention. The present invention is not limited to the embodiments described above, and various modifications and variations are possible for those with prior art knowledge in the field to which the present invention belongs, as long as they do not deviate from the essential characteristics of the present invention. Therefore, the idea of ​​the present invention should not be limited to the embodiments described above, and all technical ideas having equivalent or equivalent variations to the claims described below should be interpreted as being included within the scope of the rights of the present invention.

Claims

1. A body having a central hole and an outer surface, with a first sensitivity adjustment hole, a strain measurement hole, a second sensitivity adjustment hole, and a rigidity adjustment hole repeatedly formed along the circumferential direction; The system includes a pair of strain gauges, one attached to each side wall of the strain measurement hole, The centers of the first sensitivity adjustment hole, the second sensitivity adjustment hole, and the rigidity adjustment hole are located at the same first distance from the center of the body. The strain measurement hole has a trapezoidal shape, with the central side having a longer length than the outer circumferential side, and at least a portion of the area of ​​the trapezoidal shape is arranged such that the arc of the first distance intersects it.

2. The torque sensor module according to claim 1, wherein the first sensitivity adjustment hole and the second sensitivity adjustment hole have the same shape.

3. The torque sensor module according to claim 1, wherein there are multiple stiffness adjustment holes, and the multiple stiffness adjustment holes have the same shape as the first sensitivity adjustment hole and the second sensitivity adjustment hole.

4. The torque sensor module according to claim 1, wherein there are a plurality of rigidity adjustment holes, and the plurality of rigidity adjustment holes have different shapes from the first sensitivity adjustment hole and the second sensitivity adjustment hole.

5. The torque sensor module according to claim 1, wherein the stiffness adjustment holes are a plurality of, and the plurality of stiffness adjustment holes include two or more different shapes.

6. The torque sensor module according to claim 1, wherein the size of the rigidity adjustment hole is the same as the size of the first sensitivity adjustment hole and the second sensitivity adjustment hole.

7. The torque sensor module according to claim 1, wherein the size of the rigidity adjustment hole is larger than the size of the first sensitivity adjustment hole and the second sensitivity adjustment hole.

8. The system further includes a circuit board connected to the signal lines from each strain gauge of a pair of strain gauges mounted at each of the multiple strain measurement holes, The torque sensor module according to claim 1, wherein the circuit board digitally processes the strain sensing signal from the signal line and calculates a torque value for each of the strain measurement holes.

9. The torque sensor module according to claim 8, which calculates a torque value for a predetermined single axis without being affected by cross torque using the aforementioned torque value.

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