N-spoke torque sensor and design method

Abstract

This invention provides an N-spoke torque sensor and design method that minimizes the clearance between the inner and outer rings and features a structure with numerous thin support bases arranged in a row, making it highly resistant to crosstalk. [Solution] A torque sensor having an inner ring 110 and an outer ring 120 fastened to a first movable end and a second movable end, respectively, may be an N-poke torque sensor 100 characterized in that it includes a body 130 including an inner ring connecting portion; an outer ring connecting portion; and a body intermediate portion interposed between the inner ring connecting portion and the outer ring connecting portion, the body intermediate portion includes N sensor poles arranged at equal intervals along the circumference crossing the body intermediate portion, and to which strain gauges 140 that sense deformation due to torque between the first movable end and the second movable end are attached, and a plurality of sensitivity adjustment holes 150 and a plurality of sensor pole forming holes 160 are formed along the circumference for each of the N sensor poles, and a support base connecting the inner ring connecting portion and the outer ring connecting portion is formed between the plurality of sensitivity adjustment holes.

Description

Technical Field

[0001] The present invention relates to an N-port torque sensor and a design method, and more particularly, to an N-port torque sensor having a structure that minimizes free space and a design method.

Background Art

[0002] The structures of general torque sensors are shown in FIGS. 1 and 2.

[0003] The torque sensor 10 includes an inner ring 11 and an outer ring 13, and includes a plurality of sensor pokes 12 that connect the inner ring 1 and the outer ring 13.

[0004] Linear type strain gauges 20 are attached to both side surfaces of the sensor poke 12. In the strain gauge 20, the deformation of the sensor poke 12 is sensed to detect torque.

[0005] As shown in the figure, when there are four sensor pokes 12, a total of eight strain gauges 20 are required, one on each side surface of the sensor poke 12.

[0006] In the case of a four-poke or three-poke torque sensor that connects the inner ring 11 and the outer ring 13, the thickness and width of the sensor poke 12 are related to rigidity. That is, increasing the thickness and width can increase the rigidity. However, in this case, the sensitivity decreases, and the rigidity and sensitivity are in a trade-off relationship.

[0007] In addition, between the inner ring 11 and the outer ring 13, the rest excluding the sensor poke 12 exists as free space 5 and is vulnerable to crosstalk. Although the torque is zero, when crosstalk occurs, a torque value is expressed, and the accuracy of the torque sensor decreases.

[0008] The matters described in the technical section that forms the background of this invention are for the purpose of understanding the background of the invention and cannot be definitively considered to be prior art already known to a person with ordinary skill in the art to which this art belongs. [Prior art documents] [Patent Documents]

[0009] Republic of Korea Published Patent No. 10-2011-0058521 (Published June 1, 2011): Single-axis torque sensor with trapezoidal spokes [Overview of the project] [Problems that the invention aims to solve]

[0010] The present invention was derived to solve the above-mentioned problems, and its objective is to provide an N-spoke torque sensor and design method that have a structure in which the space between the inner and outer rings is minimized and a large number of thin support bases are arranged, making it robust against crosstalk.

[0011] Another object of the present invention is to provide an N-spoke torque sensor and design method that have fewer processing parts compared to existing structures, improve productivity, have high rigidity, and can be made lighter and smaller by reducing the thickness compared to existing structures.

[0012] Further objects of the present invention will become clearer based on the preferred embodiments described below. [Means for solving the problem]

[0013] To achieve the above objective, according to one aspect of the present invention, an N-poke torque sensor is provided having an inner ring and an outer ring fastened to a first movable end and a second movable end, respectively, the torque sensor having an inner ring connecting portion adjacent to the inner ring; an outer ring connecting portion adjacent to the outer ring; and a body intermediate portion interposed between the inner ring connecting portion and the outer ring connecting portion, wherein the body intermediate portion includes N sensor poles arranged at equal intervals along a circumference crossing the body intermediate portion, and to which strain gauges that sense deformation due to torque between the first movable end and the second movable end are attached, and a plurality of sensitivity adjustment holes and a plurality of sensor pole forming holes are formed along the circumference for each of the N sensor poles, and a support base connecting the inner ring connecting portion and the outer ring connecting portion is formed between the plurality of sensitivity adjustment holes.

[0014] The sensor poke forming holes number 2N, and may consist of pairs of two sensor poke forming holes arranged adjacent to each other on both the left and right sides of any given sensor poke.

[0015] The strain gauge can be attached to the upper or lower surface of the sensor pole.

[0016] The sensor poke has a shape corresponding to the lateral relationship between the pair of sensor poke forming holes, and the shape may be rectangular, trapezoidal, or inverted trapezoidal, depending on whether the lateral relationship is parallel, progressively closer, or progressively further apart.

[0017] The sensitivity adjustment hole can be machined into a circular shape having a predetermined diameter.

[0018] The centers of the sensitivity adjustment holes can be arranged on the circumference.

[0019] The centers of the multiple sensitivity adjustment holes, which are positioned between adjacent sensor poles, can be arranged alternately in a zigzag pattern on the inside and outside of the circumference.

[0020] When the radius of the middle part of the body is R, the width of the sensor spoke is W, the size of the sensor spoke forming hole is Ws, and the size of the sensitivity adjustment hole is Wh, the number of the sensitivity adjustment holes may be a natural number smaller than (2πR / N - W - 2Ws) / Wh.

[0021] Other aspects, features, and advantages other than those described above will become clear from the following drawings, claims, and detailed description of the invention.

Effects of the Invention

[0022] According to an embodiment of the present invention, the free space between the inner ring and the outer ring is minimized, and it has a structure in which a large number of thin support bases are arranged, and has a strong effect against crosstalk.

[0023] In addition, there are fewer processing parts for comparison with the existing structure, so productivity is improved, the rigidity is strong, the thickness of the existing structure can be reduced, and weight reduction and miniaturization are possible.

[0024] In addition, the number of strain gauges can be reduced, and there is also an effect that it can be easily and accurately attached by attaching it to the upper surface or the lower surface.

[0025] The effects obtained by the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those having ordinary knowledge in the technical field to which the present invention belongs from the following description.

Brief Description of the Drawings

[0026] [Figure 1] It is a plan view of a conventional torque sensor. [Figure 2] It is a perspective view of a conventional torque sensor. [Figure 3] It is a plan view of an N-port torque sensor according to an embodiment of the present invention. [Figure 4] It is a perspective view of an N-port torque sensor according to an embodiment of the present invention. [Figure 5] It is an exemplary view of the shapes and arrangements of various sensitivity adjustment holes of the N-port torque sensor. [Figure 6] This is an illustrative diagram of sensor pork shapes corresponding to various sensor pork forming hole shapes of the N-pork torque sensor. [Figure 7] This is a flowchart illustrating a design method for an N-pork torque sensor according to one embodiment of the present invention. [Modes for carrying out the invention]

[0027] Since the present invention can be modified in various ways and may have multiple embodiments, we will attempt to illustrate and explain specific embodiments in the drawings. However, this should not be understood as limiting the present invention to specific embodiments, but rather as including any modifications, equivalents, or substitutions that fall within the spirit and technical scope of the present invention.

[0028] When one component is described as being “linked” or “connected” to another component, it should be understood that it is either directly linked to or connected to the other component, but that other components may exist in between. On the other hand, when one component is described as being “directly linked” or “directly connected” to another component, it should be understood that no other components exist in between.

[0029] Terms such as "First," "Second," etc., may be used to describe various components, but the components shall not be limited by these terms. These terms are used solely for the purpose of distinguishing one component from another.

[0030] The terms used in this application are used solely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless they are clearly different in context. In this application, terms such as “includes” or “having” should be understood as merely indicating the existence of features, figures, stages, operations, components, parts, or combinations thereof described in the specification, and not as preemptively excluding the existence or possibility of adding one or more other features, figures, stages, operations, components, parts, or combinations thereof.

[0031] Furthermore, the components of the embodiments described with reference to each drawing are not limited to those embodiments, but may be embodied in other embodiments to the extent that the technical idea of ​​the present invention is maintained, and it goes without saying that even if separate descriptions are omitted, multiple embodiments may be re-embodied as a single integrated embodiment.

[0032] Furthermore, when explaining with reference to the attached drawings, regardless of the reference numerals used in the drawings, identical components will be given the same or related reference numerals, and redundant explanations will be omitted. When explaining the present invention, if it is determined that a specific explanation of related prior art would unnecessarily obscure the gist of the present invention, such detailed explanation will be omitted.

[0033] Figure 3 is a plan view of an N-pork torque sensor according to one embodiment of the present invention, Figure 4 is a perspective view of an N-pork torque sensor according to one embodiment of the present invention, Figure 5 is an illustrative diagram of various sensitivity adjustment hole shapes and arrangements of the N-pork torque sensor, and Figure 6 is a diagram of sensor pork shapes corresponding to various sensor pork forming hole shapes of the N-pork torque sensor.

[0034] An N-poke torque sensor 100 according to one embodiment of the present invention has N sensor pokes, and is characterized by minimizing the empty space between the sensor pokes to increase stiffness and reduce displacement due to crosstalk.

[0035] In the following explanation, we will assume that N is 4, as shown in Figures 3 and 4. This is for the convenience of understanding and explaining the invention, and it goes without saying that in the N-poke torque sensor according to the present invention, N may be 3 or a natural number of 5 or more.

[0036] The N-Poke torque sensor 100 includes an inner ring 110 and an outer ring 120. The inner ring 110 can be fastened to a first moving end of equipment (e.g., a robot joint) whose torque is to be measured, and the outer ring 120 can be fastened to a second moving end of the equipment whose torque is to be measured. In other words, the N-Poke torque sensor 100 is mounted between the first moving end and the second moving end. This connection allows the N-Poke torque sensor 100 to measure relative rotational information between the first moving end and the second moving end.

[0037] A body 130 having a predetermined thickness is interposed between the inner ring 110 and the outer ring 120. The body 130 has a shape in which the inner ring 110 is positioned on the inside and the outer ring 120 is positioned on the outside, with a hole having a second diameter (outer diameter of the inner ring 110) formed in the center of a disc having a first diameter (inner diameter of the outer ring 120).

[0038] The body 130 may include an inner ring connecting portion 131 adjacent to the inner ring 110, an outer ring connecting portion 132 adjacent to the outer ring 120, and an intermediate body portion 133 interposed between the inner ring connecting portion 131 and the outer ring connecting portion 132.

[0039] The N-spoke torque sensor 100 has N sensor pokes 134. The N sensor pokes 134 can be arranged at equal intervals along a circumference that crosses the middle section 133 of the body. Strain gauges 140 can be attached to the sensor pokes 134.

[0040] In the existing structure, numerous holes can be formed along the circumference in the spaces between the N sensor poles 134 that were previously empty spaces. That is, numerous holes can be formed in the intermediate body portion 133. The holes formed in the intermediate body portion 133 may include sensitivity adjustment holes 150 and sensor pole formation holes 160.

[0041] A thin support base 135 can be formed between adjacent sensitivity adjustment holes 150, connecting the inner ring connecting portion 131 and the outer ring connecting portion 132. The width of the support base 135 can be determined by the spacing between adjacent sensitivity adjustment holes 150. The support base 135 has a small width in the circumferential direction but sufficient thickness in the vertical direction, providing sufficient strength to the body 130.

[0042] Numerous holes are formed in the middle section 133 of the body. However, in the existing torque sensor structure shown in Figure 1, the empty space can be minimized by arranging numerous thin support bases 135 in a certain area of ​​the space that was previously empty. Minimizing the empty space increases rigidity, reduces displacement due to crosstalk, and creates a structure that is resistant to crosstalk.

[0043] The rigidity of the Body 130 allows for a reduction in the thickness of existing structural comparison sensors. With the same rigidity as a baseline, weight reduction and miniaturization are possible.

[0044] The sensitivity adjustment hole 150 can have a circular shape. A circular shape can be easily manufactured by simple drilling during machining. Therefore, a sensitivity adjustment hole 150 with a circular shape can reduce machining time and improve machining accuracy compared to other shapes. In addition, the reduction in man-hours can reduce costs and improve productivity.

[0045] Alternatively, the sensitivity adjustment holes 150 can have various shapes such as a square, a square with rounded vertices, an ellipse, a long hole, etc. The shape of such sensitivity adjustment holes 150 can be changed according to the number of support bases 135 connecting the inner ring 110 and the outer ring 120 during the design process.

[0046] By adjusting at least one of the attributes of the interval, size, and position of the sensitivity adjustment holes 150, the rigidity and sensitivity of the body 130, particularly the middle part 133 of the body, can be adjusted.

[0047] The sensitivity adjustment holes 150 can be arranged such that their centers are at the same distance from the central axis of the torque sensor 100 (see Fig. 5(a)). That is, the centers of the sensitivity adjustment holes 150 can be arranged to be on the circumference of a predetermined radius R1 centered on the central axis of the torque sensor 100.

[0048] Alternatively, the sensitivity adjustment holes 150 can be arranged such that their centers are at a near or far distance from the central axis of the torque sensor 100 according to their positions (see Fig. 5(b)). That is, the centers of the sensitivity adjustment holes 150 can be arranged to be inside (150a) or outside (150b) the circumference of a predetermined radius R1 centered on the central axis of the torque sensor 100. In this case, by arranging them alternately in a zigzag pattern inside and outside the circumference, the overall center can be positioned close to the circumference to balance the entire body 130.

[0049] The sensitivity adjustment holes 150 can also have various sizes (see Fig. 5(c)). Some of the sensitivity adjustment holes 150 can have a first diameter (r1), and the rest can have a second diameter (r2 < r1). In this case, by alternately arranging the sensitivity adjustment holes 150c with the first diameter and the sensitivity adjustment holes 150d with the second diameter, the overall balance of the body 130 can be achieved.

[0050] To increase the sensitivity (displacement) to torque, the deformation site can be induced and designed to concentrate at a specific point.

[0051] A region where deformation is to be concentrated can be designated as a sensing region, and two sensor poke forming holes 160 can be arranged, one on the left and one on the right, with the sensing region at its center. The pair of sensor poke forming holes 160 are spaced apart for a certain distance, and between them, a sensor poke 134 can be formed, which corresponds to a sensing region with high sensitivity to torque, acting as a bridge connecting the inner ring connecting portion 131 and the outer ring connecting portion 132.

[0052] A strain gauge 140 is attached to the sensor pole 134, allowing it to sense the torque applied to the device. The strain gauge 140 can be attached to at least one of the top and bottom surfaces of the sensor pole 134. Compared to existing side mounting methods, top or bottom mounting methods are easier to perform, allow for precise mounting to the target position, and improve accuracy.

[0053] In conventional structures, strain gauges had to be attached to both sides of the sensor pole, requiring a number of strain gauges equal to twice the number of sensing areas. However, in this embodiment, it is sufficient to attach only one strain gauge to the sensing area, thus reducing the number of strain gauges required.

[0054] The sensor poke 134 can have various shapes depending on the shape of the sensor poke forming hole 160. The sensor poke 134 can have a shape that corresponds to the lateral relationship of the sensor poke forming hole 160.

[0055] In one example, if the two opposing sides of a pair of sensor poke forming holes 160 are parallel (parallel side-to-side relationship), the sensor poke 134 can have a rectangular shape connecting the inner ring connecting portion 131 and the outer ring connecting portion 132 (see Figure 3).

[0056] In another example, if the two opposing sides of a pair of sensor poke forming holes 160a move closer together towards the outside (the side-to-side relationship is progressively closer), the sensor poke 134a may have a trapezoidal shape, with the inner ring connecting portion 131 being wider and the outer ring connecting portion 132 being narrower.

[0057] In yet another example, if the two opposing sides of a pair of sensor poke forming holes 160b become further apart as they move outward (the side-to-side relationship is progressively separated), the sensor poke 134b can have an inverted trapezoidal shape, with the inner ring connecting portion 131 being narrower and the outer ring connecting portion 132 being wider.

[0058] While the strain gauge 140 attached to the torque sensor 100 of an existing structure is of the linear type, the strain gauge 140 attached to the torque sensor 100 according to this embodiment may be of the double shear type.

[0059] A strain gauge is a sensor made to measure the degree of deformation of an object by creating a fixed interval and length using special foil or wire. Its resistance is proportional to the change in resistance. The change in resistance is proportional to the length of the material, but inversely proportional to the cross-sectional area.

[0060] Figure 7 is a flowchart of the design method for an N-pork torque sensor according to one embodiment of the present invention.

[0061] First, determine the capacity of the N-spoke torque sensor (step S200).

[0062] The overall size of the sensor, the size of the inner and outer rings, and the coupling method can be selected according to the sensor capacity (step S210).

[0063] Since strain gauges come in various sizes, the appropriate strain gauge can be selected for use with the sensor (step S220). The strain gauge may also be of the double shear type.

[0064] The circumferential width of the sensor pole is selected (step S230). The circumferential width of the sensor pole can be determined in accordance with the width of the strain gauge. For example, it can be selected to be equal to or greater than the width of the strain gauge.

[0065] The size and number of sensitivity adjustment holes and sensor poke formation holes are determined according to the sensor capacity (step S240).

[0066] For example, in the case of an N-poke torque sensor, since the number of sensor pokes is N, the number of sensor poke-forming holes can be calculated as 2N.

[0067] Furthermore, if the radius of the middle section of the body is R and the width of the sensor poke is W, the circumferential distance between the sensor pokes is 2πR / NW. In this case, if the size (width) of the sensor poke forming hole is Ws, the circumferential distance between the sensor poke forming holes is 2πR / NW-2Ws.

[0068] If the size (width) of the sensitivity adjustment hole is Wh, the number of possible sensitivity adjustment holes will be a natural number less than (2πR / NW-2Ws) / Wh.

[0069] Sensor-shaping holes are placed on both sides of the sensor-shaping hole, and these holes are machined into polygons rather than circles. This is to concentrate the deformation on the strain gauge attached to the sensor-shaping hole.

[0070] Although the above has been described with reference to one embodiment of the present invention, a person with ordinary skill in the art will understand that the present invention can be modified and altered in various ways without departing from the spirit and scope of the invention as described in the following claims. [Explanation of Symbols]

[0071] 100: N-spoke torque sensor 110: Inside 120: Outer ring 130: Body 131: Inner ring connection 132: Outer ring connection 133: Mid-body section 134: Sensor Pork 140: Strain Gauge 150: Sensitivity adjustment hole 160: Sensor poke forming hole

Claims

1. A torque sensor having an inner ring and an outer ring fastened to a first movable end and a second movable end, respectively, The body includes an inner ring connecting portion adjacent to the inner ring; an outer ring connecting portion adjacent to the outer ring; and an intermediate body portion interposed between the inner ring connecting portion and the outer ring connecting portion. The intermediate portion of the body includes N sensor poles arranged at equal intervals along a circumference crossing the intermediate portion of the body, to which strain gauges that sense deformation due to torque between the first movable end and the second movable end are attached; a plurality of sensitivity adjustment holes and a plurality of sensor pole forming holes are formed along the circumference for each of the N sensor poles; and a support base connecting the inner ring connecting portion and the outer ring connecting portion is formed between the plurality of sensitivity adjustment holes, characterized in that the N-pok torque sensor is characterized in that the intermediate portion of the body includes N sensor poles arranged at equal intervals along a circumference crossing the intermediate portion of the body, to which strain gauges that sense deformation due to torque between the first movable end and the second movable end are attached; a plurality of sensitivity adjustment holes and a plurality of sensor pole forming holes are formed along the circumference; and a support base connecting the inner ring connecting portion and the outer ring connecting portion is formed between the plurality of sensitivity adjustment holes.

2. The number of sensor poke forming holes is 2N. The N-poke torque sensor according to claim 1, characterized in that a pair of two sensor poke forming holes are arranged adjacent to each other on both the left and right sides of any sensor poke.

3. The N-poke torque sensor according to claim 2, characterized in that the strain gauge is attached to the upper or lower surface of the sensor poke.

4. The N-poke torque sensor according to claim 2, characterized in that the sensor poke has a shape corresponding to the lateral relationship between a pair of sensor poke forming holes, and the shape is rectangular, trapezoidal, or inverted trapezoidal, corresponding to the cases where the lateral relationship is parallel, progressively closer, or progressively further apart.

5. The N-poke torque sensor according to claim 1, characterized in that the sensitivity adjustment hole is machined into a circular shape having a predetermined diameter.

6. The N-poke torque sensor according to claim 1, characterized in that the center of the sensitivity adjustment hole is located on the circumference.

7. The N-poke torque sensor according to claim 1, characterized in that the centers of the plurality of sensitivity adjustment holes, which are arranged between adjacent sensor pokes, are alternately arranged in a zigzag pattern on the inside and outside of the circumference.

8. If the radius of the intermediate part of the body is R, the width of the sensor poke is W, the size of the sensor poke forming hole is Ws, and the size of the sensitivity adjustment hole is Wh, The N-poke torque sensor according to claim 1, characterized in that the number of sensitivity adjustment holes is a natural number less than (2πR / N-W-2Ws) / Wh.

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