Ultra-small multi-axis force torque sensor

Abstract

A micro-sized multi-axis force-torque sensor is disclosed. A micro-sized multi-axis force-torque sensor according to one embodiment of the present invention may include: a fixed portion connected to a fixed portion of a measurement portion and having a MEMS package mounted thereon; an input portion connected to a movable portion of the measurement portion, fastened on the fixed portion, and deformed by an external force transmitted through the movable portion; and a MEMS package that receives translational and rotational motions caused by the deformation of the input portion and detects a multi-axis force-torque.

Description

Technology Field

[0001] The present invention relates to a force-torque sensor, and more specifically, to an ultra-compact multi-axis force-torque sensor. Background Technology

[0003] In industrial articulated robots or actuators, torque sensors that measure only torque, and force-torque sensors that measure both force and torque, may be used. In addition, torque sensors and force-torque sensors are used in various other industrial fields.

[0004] Among these force-torque sensors, multi-axis sensors, that is, sensors that measure forces in multiple directions and torque (rotational moment) generated by forces in multiple directions, may be provided. For example, there is a 6-axis sensor capable of measuring forces in the x, y, and z-axis directions and rotational moments about the x, y, and z axes.

[0005] A force-torque sensor corresponding to such a 6-axis sensor comprises a fixed part, a movable part capable of moving when force is applied, an elastic deformation part between the fixed part and the movable part, and a strain gauge attached to the elastic deformation part. Therefore, when force is applied to the movable part of the force sensor, the elastic deformation part undergoes elastic deformation, and the strain gauge measures the amount of deformation of the elastic deformation part to measure the applied force.

[0006] In the case of such conventional force-torque sensors, the elastic deformation part has a cross shape, and the attachment of a strain gauge is required, which limits miniaturization.

[0007] The matters described in the technical background section of this invention are for the purpose of understanding the background of the invention and cannot be concluded as prior art already known to a person with ordinary knowledge in the field to which this technology belongs. Prior art literature

[0009] Korean Patent Publication No. 10-2023-0128746 (Published Sep 5, 2023) - Force Sensor The problem to be solved

[0010] The present invention aims to provide a micro-sized multi-axis force-torque sensor capable of measuring force in the x-axis, y-axis, and z-axis directions and torque based on the x-axis, y-axis, and z-axis while having a small size by using MEMS instead of the strain gauge of a conventional sensor.

[0011] Other objects of the present invention will become more apparent through the preferred embodiments described below. means of solving the problem

[0013] According to one aspect of the present invention, a micro-sized multi-axis force-torque sensor is provided, comprising: a fixed portion connected to a fixed portion of a measurement portion and having a MEMS package mounted thereon; an input portion connected to a movable portion of the measurement portion, fastened to the fixed portion, and deformed by an external force transmitted through the movable portion; and a MEMS package that receives translational motion and rotational motion caused by the deformation of the input portion and detects a multi-axis force-torque.

[0014] The above input section may include a cylindrical input section body having a vertical hollow formed inside and a plurality of side holes formed in a horizontal radial direction around the circumference.

[0015] The sensitivity and intensity regarding the degree of deformation of the input end body can be adjusted in accordance with at least one of the size and quantity of the side holes.

[0016] The above input body may be an elastic body.

[0017] The above MEMS package may include: a MEMS connecting rod in which the upper end of the rod body is inserted and secured into the hollow; a MEMS in which the lower end of the rod body of the MEMS connecting rod is connected to a moving driver and which detects multi-axis force torque from a position change of the moving driver relative to a fixed driver; a MEMS PCB on which the MEMS is mounted and which has an electrical connection established with the MEMS to process a sensing signal; and a MEMS cover that seals the MEMS.

[0018] The above MEMS may include a moving driver that performs three-axis translational motion and three-axis rotational motion by an external force; and a fixed driver positioned to be fixed adjacent to the moving driver.

[0019] The above-mentioned moving driver is positioned in the center, and the above-mentioned fixed driver is positioned around the above-mentioned child driver, and the above-mentioned fixed driver includes at least one pair of fixed comb members for each side of the above-mentioned moving driver, and a plurality of moving electrodes are provided on the outer side of the body of the above-mentioned moving driver, and a plurality of fixed electrodes adjacent to the moving electrodes are provided on one side of the fixed comb member, and the plurality of moving electrodes and the plurality of fixed electrodes can be arranged in an intersecting manner so as to face each other.

[0020] Other aspects, features, and advantages other than those described above will become apparent from the following drawings, claims, and detailed description of the invention. Effects of the invention

[0022] According to an embodiment of the present invention, by using MEMS instead of a strain gauge of a conventional sensor, it is possible to measure force in the x-axis, y-axis, and z-axis directions and torque based on the x-axis, y-axis, and z-axis while having a small size.

[0023] The effects obtainable from the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below. Brief explanation of the drawing

[0025] FIG. 1 is a perspective view of a micro-multi-axis force-torque sensor according to one embodiment of the present invention, FIG. 2 is an exploded perspective view of the ultra-small multi-axis torque sensor shown in FIG. 1. FIG. 3 is a cross-sectional view of the ultra-compact multi-axis torque sensor shown in FIG. 1, FIG. 4 is a perspective view and a cross-sectional view of the input end, FIG. 5 is a perspective view and a cross-sectional view of the fixed part, FIG. 6 is a perspective view and a cross-sectional view of a MEMS package in an assembled state and a disassembled state, FIG. 7 is a cross-sectional view of a MEMS package, Figure 8 is a structural diagram of a MEMS, FIG. 9 is a diagram showing the 6-axis force-torque sensing principle of MEMS. Figure 10 is an example diagram of the analysis of the x, y, and z axis forces at the input end. FIG. 11 is an example diagram of the analysis of x, y, and z axis torques at the input end. Specific details for implementing the invention

[0026] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the invention to specific embodiments, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0027] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0028] Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another.

[0029] The terms used herein are merely for describing specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “comprising” or “having” are intended to indicate the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0030] Furthermore, the components of the embodiments described with reference to each drawing are not limited to the respective embodiments and may be implemented to be included in other embodiments within the scope of maintaining the technical spirit of the present invention. It is also obvious that multiple embodiments may be re-implemented as a single embodiment that integrates multiple embodiments, even if a separate description is omitted.

[0031] Furthermore, in the description referring to the attached drawings, identical components are assigned the same or related reference numerals regardless of drawing symbols, and redundant descriptions thereof are omitted. In describing the present invention, if it is determined that a detailed description of related prior art could unnecessarily obscure the essence of the present invention, such detailed description is omitted.

[0033] FIG. 1 is a perspective view of a micro-multi-axis force-torque sensor according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of the micro-multi-axis torque sensor shown in FIG. 1, FIG. 3 is a cross-sectional view of the micro-multi-axis torque sensor shown in FIG. 1, FIG. 4 is a perspective view and cross-sectional view of an input end, FIG. 5 is a perspective view and cross-sectional view of a fixed part, FIG. 6 is a perspective view and cross-sectional view of a MEMS package in an assembled state and an exploded state, FIG. 7 is a cross-sectional view of a MEMS package, FIG. 8 is a structural diagram of a MEMS, FIG. 9 is a diagram showing the 6-axis force-torque sensing principle of a MEMS, FIG. 10 is an example diagram of the analysis of x, y, and z-axis forces of the input end, and FIG. 11 is an example diagram of the analysis of x, y, and z-axis torque of the input end.

[0034] A micro-multi-axis force-torque sensor according to one embodiment of the present invention is characterized by having a small size while being able to measure force in the x-axis, y-axis, and z-axis directions and torque based on the x-axis, y-axis, and z-axis by using MEMS instead of the strain gauge of a conventional sensor.

[0035] The ultra-compact multi-axis force-torque sensor (100) according to the present embodiment may include a fixed part (120) and an input part (110) that are connected to a measurement part, such as a robot joint, to measure force and torque. The measurement part is assumed to be a point where the fixed part and the movable part are connected by being engaged relatively.

[0036] The fixed part (120) is fastened to the fixed end of the measurement area and has a fixed body that is not deformed by external force.

[0037] The input terminal (110) is connected to the moving terminal of the measurement area and has a body whose shape is deformed when a force is applied from the outside (moving terminal).

[0038] A MEMS package (130) is installed interposed between the fixed part (120) and the input end (110), and the MEMS (131) of the MEMS package (130) can measure the deformation of the input end (110) and output values ​​related to multi-axis force and multi-axis torque.

[0039] The input section (110) may be a hollow cylindrical structure. The input section body (111) serves as the basic framework, and a hollow (112) is formed inside in the vertical direction (z-axis direction).

[0040] A plurality of side holes (114) are formed around the perimeter of the input body (111) in a direction toward the z-axis, that is, in a horizontal radial direction. The plurality of side holes (114) can be arranged at equal intervals. When there are N side holes (114), the angle between the side holes (114) can be 360˚ / N.

[0041] On the upper surface (113) of the input body (111), an upper surface hole (1131) may be formed in a vertical direction (z-axis direction) at the center including a vertical central axis. An assembly hole (1132) for connection with the moving end of the measurement part may be formed around the perimeter of the upper surface (113). One or more assembly holes (1132) may be formed.

[0042] The input end body (111) may be an elastic body. That is, the shape of the input end body (111) may be deformed by an external force, particularly a force transmitted from the moving end of the measurement part.

[0043] The degree to which the shape of the input end body (111) is deformed corresponds to the sensitivity of the force torque sensor (100) according to the present embodiment. In addition to the material of the input end body (111), the size of the upper surface hole (1131) formed in the input end body (111), the size and / or quantity of the side hole (114), the diameter of the hollow (112), etc., may be parameters that control the sensitivity and strength of the sensor.

[0044] A first fastening groove (115) and a first fastening piece (116) may be alternately formed at the bottom of the input body (111). The first fastening groove (115) and the first fastening piece (116) function as fastening parts for fastening with the fixing part (120).

[0045] The fixed part (120) is positioned at the bottom in the drawing and includes a cylindrical body as a basic frame. A second fastening piece (123) corresponding to a first fastening groove (115) and a second fastening groove (122) corresponding to a first fastening piece (116) may be formed on the perimeter of the fixed part body (121), particularly on the upper surface. That is, the second fastening piece (123) is inserted and fastened into the first fastening groove (115), and the first fastening piece (116) is inserted and fastened into the second fastening groove (122), so that the input end (110) can be fastened on the fixed part (120).

[0046] A PCB holder (124) having a lower height than the second fastening piece (123) may be formed on one side of the upper surface of the fixed part (120). The PCB holder (124) is a space in which a MEMS PCB (133) of the MEMS package (130) described later is mounted, and a cable (140) connected to the MEMS PCB (133) to transmit a measurement signal to the outside is mounted.

[0047] A MEMS package mounting portion (125) may be provided at the inner center of the fixed portion (120). The aforementioned second fastening groove (122), second fastening piece (123), and PCB holder (124) are arranged around the perimeter of the MEMS package mounting portion (125). The MEMS package mounting portion (125) may have a concave groove shape with a lower height compared to the second fastening groove (122). A MEMS package (130), which will be described later, is mounted on the MEMS package mounting portion (125) and is fixed so that its position does not become twisted.

[0048] The MEMS package (130) is a structure in which the MEMS (131) is packaged, is interposed between the fixed part (120) and the input end (110), senses deformation of the input end (110), and outputs it as a signal.

[0049] The MEMS package (130) may include a MEMS connecting rod (132) whose upper end is connected to an input terminal (110) to transmit deformation of the input terminal (110), a MEMS (131) (particularly a moving driver) to which the lower end of the MEMS connecting rod (132) is connected, a MEMS PCB (133) that processes signals for 3-axis movement and 3-axis rotation of the MEMS (131), and a MEMS cover (134) that packages the MEMS (131) and the MEMS PCB (133).

[0050] The MEMS connecting rod (132) has a rod body that is long in the vertical direction. A coupling head (1321) is formed at the top of the rod body and is inserted and coupled into the upper surface hole (1131) of the input terminal (110). Both the rod body and the coupling head (1321) have a cylindrical shape, and the diameter of the coupling head (1321) may be smaller than the diameter of the rod body. A coupling projection (1322) is installed protruding from the bottom of the rod body, and the coupling projection (1322) can be connected to the MEMS (131), particularly the MEMS moving driver.

[0051] The MEMS (131) is placed on the MEMS PCB (133). A MEMS cover (134) is spaced apart from the top of the MEMS (131) and a portion of the top of the MEMS PCB (133). By the MEMS cover (134), the MEMS (131) and a portion of the MEMS PCB (133) are isolated from the external environment, thereby preventing the entry of foreign substances.

[0052] A through hole is formed in the center of the MEMS cover (134) through which a MEMS connecting rod (132) is installed. The lower part of the MEMS connecting rod (132) passes through the through hole, and the connecting projection (1322) at the bottom can be connected to the MEMS (131).

[0053] A connector (150) is connected to the lower part of the MEMS PCB (133), and a cable (140) is connected to the connector (150) to output a sensing signal regarding multi-axis force and multi-axis torque to the outside of the sensor.

[0054] When a 6-axis force torque is applied to the upper surface (113) of the body of the input terminal (110), the input terminal (110) is deformed. The deformation of the input terminal (110) is transmitted to the MEMS connecting rod (132) connected to the input terminal (110). Then, the moving driver of the MEMS (131) connected to the lower end of the MEMS connecting rod (132) is able to detect the 6-axis force torque.

[0055] In one example, the ultra-small multi-axis force torque sensor (100), which is completed by assembling the fixed part (120) and the input part (110), may be an ultra-small structure with a sensor outer diameter of 10 mm or less.

[0056] The MEMS (131) may have a rectangular plate shape with a size of 3 mm x 3 mm. The MEMS (131) is divided into a moving driver and a fixed end, and can detect 6-axis force torque by interpreting the difference in signals caused by the position change of the moving driver relative to the fixed end.

[0057] The MEMS PCB (133) may have a thickness (t) of 0.6, and the connector (150) may be composed of 21 pins. And the cable (140) may be an FPC (flexible printed circuit) cable.

[0058] According to the present embodiment, the conventional method of detecting 6-axis force torque using a strain gauge can be miniaturized and the manufacturing cost reduced by using MEMS.

[0059] Referring to FIG. 7, the structure of the MEMS package (130) is illustrated in detail. After the MEMS (131) is mounted on the PCB (133), it is circuit-connected to a signal processing IC (1331) via wire bonding (1333). The signal processing IC (1331) is connected to an external electrode (1332) via wires, and can process the signal detected by the MEMS (131) and output it through the external electrode (1332). Then, the lower end of the MEMS connecting rod (132) is connected to the moving driver of the MEMS (131), and the MEMS (131) can be sealed with a MEMS cover (134) to form a package.

[0060] When connecting the fixed part (120) and the input terminal (110), they can be connected using bonding or the like. This is because screw connection is difficult due to the ultra-small size. When the lower part of the MEMS package (130) is also seated on the fixed part (120), it can be connected through a bonding method. In addition, when connecting the upper part of the MEMS connecting rod (132) to the input terminal (110), it can be connected to the input terminal body (111) through a bonding method.

[0061] Referring to FIGS. 8 and 9, the structure of the MEMS (131) and the principle of detecting 6-axis force torque are illustrated.

[0062] The MEMS (131) may be an inertial sensor capable of measuring three-axis translational motion and three-axis rotational motion. The MEMS (131) may include a moving driver (210) that performs three-axis translational motion and three-axis rotational motion by an external force, and a fixed driver (220) that is positioned to be fixed adjacent to the moving driver (210).

[0063] The fixed driver (220) may have at least one pair of fixed comb members for each side of the movable driver (210) (e.g., four sides in the case of a square). Additionally, it may further include a ground electrode (230) disposed around the movable driver (210) and the fixed driver (220). The ground electrode (230) may be connected to the movable driver (210).

[0064] The moving driver (210) and the fixed driver (220) can be fabricated using a monolithic substrate. The MEMS (131) can be fabricated by arranging the structures of the moving driver (210), the fixed driver (220), and the ground electrode (230) all planarly on a single layer.

[0065] A movable driver (210) may be positioned in the center, and a fixed driver (220) may be positioned around the movable driver (210). The fixed driver (220) may include a plurality of pairs of fixed comb members (221, 222).

[0066] A pair of fixed comb members (221, 222) may be disposed on one side of the moving driver (210). The pair of fixed comb members (221, 222) may include a first fixed comb member (221) and a second fixed comb member (222).

[0067] The moving driver (210) may include, for example, a rectangular body, and a plurality of moving electrodes (211) may be provided on the outer side of the body. And a plurality of fixed electrodes (2211, 2221) adjacent to the moving electrodes (211) may be provided on one side of each fixed comb member (221, 222). The plurality of moving electrodes (211) and the plurality of fixed electrodes (2211, 2221) may be arranged in an alternating manner so as to face each other.

[0068] A MEMS connecting rod (132) is connected to the moving driver (210), so that a 6-axis force torque is transmitted according to the deformation of the input terminal (110) due to an external force, thereby enabling 3-axis translational motion and 3-axis rotational motion.

[0069] The 6-axis force torque can be detected by detecting the signal difference according to the mutual positional relationship between the moving electrode (211) and the fixed electrode (2211, 2221) according to this 6-axis movement.

[0070] For example, when the moving driver (210) moves along the x-axis, the moving electrode (211) arranged perpendicular to the x-axis moves closer to one of the left and right fixed electrodes (2211, 2221) and further away from the other (see (a)).

[0071] When the moving driver (210) moves along the y-axis, the moving electrode (211) arranged perpendicular to the y-axis moves closer to one of the left and right fixed electrodes (2211, 2221) and further away from the other (see (b)).

[0072] When the moving driver (210) moves along the z-axis, the height of the moving electrode (211) changes. In this case, the first fixed electrode (2211) of the first fixed comb member (221) and the second fixed electrode (2221) of the second fixed comb member (222) have different heights, so the change in the height of the moving electrode (211) can be detected (see (c)).

[0073] When the moving driver (210) rotates about the x-axis, the moving electrode (211) is tilted relative to the fixed electrode (2211, 2221) when viewed in the yz plane (see (d)).

[0074] When the moving driver (210) rotates around the y-axis, the moving electrode (211) becomes tilted relative to the fixed electrode (2211, 2221) when viewed in the xz plane (see (e)).

[0075] When the moving driver (210) rotates around the z-axis, the moving electrode (211) is tilted between the fixed electrodes (2211, 2221) when viewed in the xy plane (see (d)).

[0076] By detecting the position change (movement or tilting) of the movable electrode (211) relative to the fixed electrode (2211, 2221), it is possible to detect 6-axis force torque.

[0077] FIG. 10 illustrates an example of an analysis simulation for x, y, and z axis forces (Fx, Fy, Fz) according to deformation of the input end of a micro-sized multi-axis force-torque sensor according to the present embodiment.

[0078] Figure 11 illustrates an example of an analysis simulation for x, y, and z axis torques (Tx, Ty, Tz) according to deformation of the input end of a micro-sized multi-axis force-torque sensor according to the present embodiment.

[0079] Although the present invention has been described above with reference to embodiments thereof, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the spirit and scope of the invention as described in the following claims. Explanation of the symbols

[0080] 100: Ultra-compact multi-axis force-torque sensor 110: Input terminal 111: Input body 112: Communist China 113: Top surface 1131: Top surface hole 1132: Assembler 114: Side attack 115: 1st connection home 116: First Concluding Part 120: Fixed part 121: Fixed body 122: 2nd Signing Home 123: Second Conclusion 124: PCB stand 125: MEMS package mounting area 130: MEMS package 131: MEMS 132: MEMS connecting rod 1321: Connecting head 1322: Connecting protrusion 133: MEMS PCB 134: MEMS cover 140: Cable 150: Connector 210: Move driver 211: Moving electrode 220: Fixed driver 221: First fixed comb member 222: Second fixed comb member 2211: First fixed electrode 2221: Second fixed electrode 230: Ground electrode

Claims

Claim 1 A micro-sized multi-axis force-torque sensor comprising: a fixed portion connected to a fixed portion of a measurement portion and on which a MEMS package is seated; an input portion connected to a movable portion of the measurement portion, fastened on the fixed portion, and deformed by an external force transmitted through the movable portion; and a MEMS package that receives translational and rotational motions caused by the deformation of the input portion and detects multi-axis force-torque. Claim 2 A micro-multi-axis force-torque sensor according to claim 1, characterized in that the input end comprises a cylindrical input end body having a vertical hollow formed inside and a plurality of side holes formed in a horizontal radial direction around the circumference. Claim 3 A micro-multi-axis force-torque sensor according to claim 2, characterized in that the sensitivity and strength regarding the degree of deformation of the input end body are adjusted in correspondence with at least one of the size and quantity of the side holes. Claim 4 A micro-multi-axis force-torque sensor characterized in that, in paragraph 2, the input end body is an elastic body. Claim 5 In paragraph 2, the MEMS package comprises: a MEMS connecting rod in which the upper end of the rod body is inserted and secured into the hollow; a MEMS in which the lower end of the rod body of the MEMS connecting rod is connected to a moving driver and detects multi-axis force torque from a position change of the moving driver relative to a fixed driver; a MEMS PCB on which the MEMS is mounted and an electrical connection is established with the MEMS to process a sensing signal; and a MEMS cover that seals the MEMS. Claim 6 A micro-sized multi-axis force-torque sensor according to claim 5, wherein the MEMS comprises a moving driver that performs three-axis translational motion and three-axis rotational motion by an external force; and a fixed driver disposed to be fixed adjacent to the moving driver. Claim 7 A micro-multi-axis force-torque sensor according to claim 6, wherein the moving driver is positioned in the center and the fixed driver is positioned around the moving driver, the fixed driver includes at least one pair of fixed comb members for each side of the moving driver, a plurality of moving electrodes are provided on the outer side of the body of the moving driver, a plurality of fixed electrodes adjacent to the moving electrodes are provided on one side of the fixed comb member, and the plurality of moving electrodes and the plurality of fixed electrodes are arranged in an intersecting manner so as to face each other.

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