KR102183179B1 - Multi-axis force-torque sensor using straingauges - Google Patents

Abstract

The present invention relates to a strain-gauge type multiaxial force-torque sensor. The strain-gauge type multiaxial force-torque sensor includes: an upper cover; a cylindrical lower cover; an elastic body forming multiple points for sensing a surface strain rate by including an upper plate fastened with a lower part of the upper cover, a lower plate mounted inside the lower cover and having a larger diameter than the upper plate, and a plurality of beams connecting the upper and lower plates; and a circuit board part mounted between the lower cover and the elastic body and processing the surface strain rate of the elastic body measured through a strain gauge into an analogue signal and a digital signal. Each of the plurality of beams includes: a horizontal member connected with the lower plate; and a vertical member extended vertically from the center of the horizontal member and having an end bent to be connected to the upper plate. A groove is formed inside the vertical member so as to increase the surface strain rate. Therefore, the present invention can expand use in industrial fields by lowering sensor prices through an elastic body structure, which is easy to machine and increases a surface strain rate, can enable convenient use, and can perform real time force control by measuring force components in three directions and torque components in three directions at the same time.

Description

Strain gauge type multi-axis force torque sensor {MULTI-AXIS FORCE-TORQUE SENSOR USING STRAINGAUGES}

The present invention relates to a strain gauge type multi-axis force torque sensor, and more particularly, by attaching a strain gauge to an elastic body connected by a plurality of beams between the upper and lower plates to sense the surface strain, the processing of the elastic body is easy and multi-point It relates to a strain gauge type multi-axis force torque sensor that can effectively detect force in

In order to use the robot manipulator for precision assembly, machining such as grinding, polishing, deburring, or automation such as meat and fish processing, the position of the robot manipulator, as well as the force and torque acting on the end devices are measured and feedback control. It is necessary to do. That is, in order to automate complex and delicate tasks, it is necessary to be able to simultaneously perform position control and force control, and there is an increasing need to detect the force acting between the robot and the external work piece.

Since these forces and torques act in arbitrary directions in the three-dimensional space, when using the conventional force sensor and torque sensor with a linear degree of freedom, several sensors must be used simultaneously, but this is not desirable due to space limitations. Therefore, a 6-axis force torque sensor is needed that can measure the force in three directions and the torque in three directions at the same time.

The method of measuring force in robot work includes measuring by installing a torque sensor on the joint of the robot according to the measuring position, measuring by installing a force torque sensor on the wrist or hand of the robot manipulator, and measuring the force on the assembly table of the work piece. There is a method of measuring by installing a torque sensor.

Among them, it is known that it is generally most advantageous to measure the force and torque acting on the robot wrist, and for this purpose, a number of six-axis force torque sensors that can be mounted on the robot wrist have been studied.

The elastic element used in the 6-axis force torque sensor using a strain gauge must have sufficient elastic deformation to effectively measure the applied force and torque, but it is small in order not to significantly change the position and direction of the robot end device. It is desirable that elastic deformation occurs only in the part. In addition, it must be structurally designed to prevent damage to the sensor from overload or impact that may act on the sensor.

The six-axis force torque sensor designed by Scheinmman in the mid-1970s attaches 16 semiconductor strain gauges, one per each side of four orthogonal deflection bars, and each of them is composed of a bridge, so that its output voltage is It is designed to be proportional to the force component in the direction perpendicular to the plane of the strain gauges. By appropriately arithmetically adding or subtracting these outputs, the force and torque components in three directions can be measured. This method has the advantage of being relatively easy to manufacture, but the accuracy is low by about 5%, and the measurement speed is low because the force or torque must be calculated using an arithmetic method rather than measuring directly.

Yabaki devised an orthogonal elastomer structure consisting of eight parallel leaf springs, but in this structure, six Wheatstone bridges are composed of 24 strain gauges, and force and torque components are directly derived from the output of the bridge without arithmetic calculations. Can be measured. The error of this load cell is about 2% for the force component and 3 to 5% for the torque component.

Hatamura devised a 6-axis force torque sensor using a parallel plate to measure force components and a radial plate to measure torque. The error of this sensor is about 2% in the case of the force component and 3% in the case of the torque component.

Korean Patent Registration No. 10-0199691 (1999.03.05) is a six-component load cell capable of simultaneously measuring a force component in three directions and a moment component in three directions, the upper and lower parts forming a connection part and a protruding jaw in an orthogonal direction A sensing unit consisting of a cross-shaped beam divided into a ring and a horizontal and vertical beam, forming a through hole of a binocular structure and four holes in the upper and lower left and right sides of the beam, and to which a plurality of strain gauges are attached; Consists of an open path corresponding to the protruding jaws of the upper and lower rings of the sensing unit, and an upper and lower case having a plurality of assembly holes, and an outer case having a lead-out hole for drawing input and output lines to one side of the lower gate It relates to a 6-component load cell, characterized in that the.

Korean Patent Publication No. 10-2011-0098070 (2011.09.01) relates to a six-axis force-moment sensor, an outer ring formed in a ring shape, an inner block disposed inside the outer ring, and one end A frame including four horizontal beams connected to the outer ring, the other end connected to the inner block, and spaced apart from each other at a 90 degree angle and arranged in a cross shape; A plurality of strain gauges coupled to the frame; And a control unit that calculates an external force applied to the frame based on the data output from the strain gauge, so that the external force can be accurately measured by minimizing a mutual interference error between horizontal beams.

However, the conventional strain gauge type 6-axis force torque sensor is too expensive to be widely used in industrial fields. In addition, in the case of the 6-axis force torque sensor of the wireless communication method, it is inconvenient to use due to the large number of accessories, and it is difficult to control real-time force due to a long measurement time.

Korean Patent Registration No. 10-0199691 (1999.03.05) Korean Patent Publication No. 10-2011-0098070 (2011.09.01)

According to an embodiment of the present invention, a strain gauge is attached to an elastic body connected by a plurality of beams between the upper and lower plates to sense the surface strain, thereby making it easy to process the elastic body and effectively sensing force at multiple points. We want to provide a multi-axis force torque sensor.

According to an embodiment of the present invention, the upper plate of the elastic body is formed relatively smaller than the lower plate, and by connecting them with a plurality of beams of a T-shaped vertical member and a horizontal member, the machinability can be excellent, and the vertical member of the plurality of beams It is intended to provide a strain gauge type multi-axis force torque sensor capable of increasing the surface strain by forming a circular or elliptical groove inside.

An embodiment of the present invention is to provide a strain gauge type multi-axis force torque sensor capable of transmitting and receiving via wireless communication with a controller by embedding a battery in a sensor and installing an antenna outside the sensor.

Among the embodiments, the strain gauge type multi-axis force torque sensor includes an upper cover, a cylindrical lower cover, an upper plate fastened to a lower portion of the upper cover, and a lower plate having a diameter larger than that of the upper plate. An elastic body including a plurality of beams connecting between the upper plate and the lower plate to form multiple points for detecting the surface strain, and the surface strain of the elastic body mounted between the lower cover and the elastic body and measured through a strain gauge are analogue And a circuit board for digital signal processing, wherein each of the plurality of beams includes a horizontal member connected to the lower plate and a vertical member extending vertically from the center of the horizontal member and bent at an end thereof to be connected to the upper plate, It characterized in that the groove is formed inside the vertical member to increase the strain rate.

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The elastic body connects the upper plate and the lower plate with 3 or 4 beams, and detects the surface strain at a point where the surface strain is high in the T-shaped portion formed by the horizontal member and the vertical member of the beam. Strain gauges can be distributed and attached.

In the elastic body, one of the upper plate and the lower plate is formed in a circular plate shape to be connected in surface contact with one of the upper cover and the lower cover, and the other one of the upper plate and the lower plate is formed in a ring shape. It can be connected by making edge contact with the other of the lower covers.

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Among the embodiments, the strain gauge type multiaxial force torque sensor may be fixedly installed on a corresponding cover through a signal processing circuit board in one of the space between the upper cover and the elastic body or between the lower cover and the elastic body. have.

The signal processing circuit board may include a Wheatstone bridge circuit connected to the plurality of strain gauges, an amplifying circuit, a zero adjustment circuit, a microcontroller, and a communication terminal.

Among the embodiments, the strain gauge type multi-axis force torque sensor has a wireless antenna or USB connection port formed on one side of the lower cover, and a communication terminal installed on the signal processing circuit board through the wireless antenna or USB connection port It can be connected to enable wireless communication or USB communication.

Among the embodiments, the strain gauge type multi-axial force torque sensor may install a battery in a space between the elastic body and the signal processing circuit board.

Among the embodiments, the strain gauge type multi-axis force torque sensor includes a cap-shaped upper cover, a cylindrical lower cover having a wireless antenna or USB connection port formed on one side thereof, a plate-shaped upper plate fixedly coupled to the upper cover, and the lower part. A ring-shaped lower plate fixedly coupled to the cover and having a diameter larger than the diameter of the upper plate, and formed of four beams connecting the upper plate and the lower plate, wherein each of the four beams is a horizontal member connected to the lower plate and the horizontal member An elastic body having a vertical member extending vertically from the center of the upper plate and connected to the upper plate, and having a circular or elliptical groove formed inside the vertical member, and each attached to the four beams to detect surface strain It includes a strain gauge, fixedly installed on the lower cover through a signal processing circuit board in the space between the lower cover and the elastic body, and applied to the x, y, and z axes by signal processing of the detection signal of the strain gauge. The force component and/or the torque component may be measured, and the measurement result may be transmitted through wireless communication or USB communication through the wireless antenna or the USB connection port.

The disclosed technology can have the following effects. However, since it does not mean that a specific embodiment should include all of the following effects or only the following effects, it should not be understood that the scope of the rights of the disclosed technology is limited thereby.

The multiaxial force torque sensor of the strain gauge method according to an embodiment of the present invention attaches a strain gauge to an elastic body connecting the upper and lower plates with three or four beams, so that the force component and/or torque at multiple points having a high surface strain Ingredients can be detected.

The strain gauge type multi-axis force torque sensor according to an embodiment of the present invention detects force by digging a circular or elliptical groove inside the vertical member among a plurality of beams composed of a T-shaped vertical member and a horizontal member to increase the surface strain. It can be effectively done, and the sizes of the upper and lower plates connected by a plurality of beams are different, and one of the upper and lower plates is filled in the middle to connect the cover plate, and the other side is empty to connect the cover plate through the rim. Can be easily machined.

The strain gauge type multi-axis force torque sensor according to an embodiment of the present invention can transmit/receive via wireless communication with a controller by embedding a battery in the sensor and installing an antenna outside the sensor.

Therefore, the multi-axis force torque sensor of the strain gauge method according to an embodiment of the present invention can reduce the cost of the sensor through a structure design that can be easily manufactured at low cost, thereby expanding its use in industrial sites.

1A and 1B are perspective and partially cut-away perspective views illustrating a strain gauge type multi-axis force torque sensor according to an embodiment of the present invention.
2A to 2C are perspective views, partially cut-away perspective views, and a bottom perspective view showing the elastic body in FIG. 1.
3 is a view showing a state in which a strain gauge is attached to horizontal and vertical members of the beam in the elastic body of FIG. 2.
4 is a graph measuring the surface strain according to the thickness of the horizontal member of the beam in the elastic body of FIG. 2.
FIG. 5 is a graph illustrating a measurement of surface strain according to the thickness of a vertical member of a beam in the elastic body of FIG. 2.
6 is a diagram showing a configuration of a signal processing circuit mounted on the circuit board of FIG. 1.
7 is a graph showing force measurement results for a step-shaped static load (Fz) in the z-axis direction in the strain gauge type multi-axis force torque sensor according to an embodiment of the present invention.
8A to 8C are comparative graphs showing force measurement results for dynamic loads in the three (x, y, z) directions in the present invention and the conventional force torque sensor.
9 is a graph showing linearity and hysteresis of a strain gauge multi-axis force torque sensor according to an embodiment of the present invention.
10A to 10C are photographs showing a model actually manufactured of a strain gauge type multi-axis force torque sensor according to an embodiment of the present invention.

Since the description of the present invention is merely an embodiment for structural or functional description, the scope of the present invention should not be construed as being limited by the embodiments described in the text. That is, since the embodiments can be variously changed and have various forms, the scope of the present invention should be understood to include equivalents capable of realizing the technical idea. In addition, since the object or effect presented in the present invention does not mean that a specific embodiment should include all of them or only those effects, the scope of the present invention should not be understood as being limited thereto.

Meanwhile, the meaning of terms described in the present application should be understood as follows.

Terms such as "first" and "second" are used to distinguish one component from other components, and the scope of rights is not limited by these terms. For example, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component.

Singular expressions are to be understood as including plural expressions unless the context clearly indicates otherwise, and terms such as “comprise” or “have” refer to implemented features, numbers, steps, actions, components, parts, or It is to be understood that it is intended to designate that a combination exists and does not preclude the presence or addition of one or more other features or numbers, steps, actions, components, parts, or combinations thereof.

All terms used herein have the same meaning as commonly understood by one of ordinary skill in the field to which the present invention belongs, unless otherwise defined. Terms defined in commonly used dictionaries should be construed as having meanings in the context of related technologies, and cannot be construed as having an ideal or excessive formal meaning unless explicitly defined in the present application.

1A-1B are a perspective view and a partially cut-away perspective view illustrating a strain gauge type multi-axis force torque sensor according to an embodiment of the present invention.

1A and 1B, the multi-axial force torque sensor 100 includes an upper cover 110, an elastic body 130, a circuit board portion 150, and a lower cover 170.

The upper cover 110 has a cap shape, and may be connected through an elastic body 130 and a screw 113 disposed at the bottom by providing screw connection holes 111 at regular intervals along the rim of the upper surface. In one embodiment, six screw connection holes 111 may be disposed at equal intervals in the upper cover 110, and the number of screw connection holes 111 is not limited thereto, and the upper cover 110 and the elastic body 130 ) It can be provided in an appropriate number that can be fixed and fastened between.

The elastic body 130 may be installed between the upper cover 110 and the lower cover 170. In one embodiment, the upper part of the elastic body 130 may be fastened to the upper cover 110 and the lower part may be fastened to the lower cover 170. Here, a gap is formed between the upper cover 110 and the lower cover 170 fastened to the elastic body 130, so that when an overload acts on the elastic body 130, the upper cover 1100 contacts the lower cover 170 and no longer By preventing deformation from occurring, damage to the elastic body 130 can be prevented.

The circuit board part 150 is fixedly installed in the space between the lower cover 170 and the elastic body 130, and the PCB mounting base 151 is installed at the inner lower end of the lower cover 170, and the circuit board on the PCB mounting base 151 153 may be installed, and a battery 155 may be installed on the circuit board 153. Here, analog and digital signal processing circuits may be formed on the circuit board 153. The battery 155 may provide operation power to the signal processing circuit formed on the circuit board 153.

The lower cover 170 has a cylindrical shape, and a circuit board portion 150 and an elastic body 130 may be installed therein. In one embodiment, the lower cover 170 includes a charging indicator 171 indicating the state of charge of the battery 155 by LED lighting on one side and a battery charging port 173 for charging the battery 155. In addition, a wireless antenna 175 may be installed. The lower cover 170 may include a status indicator 177 indicating the state of the multi-axis force torque sensor 100 by LED lighting on the other side.

In one embodiment, the multi-axial force torque sensor 100 detects the surface strain by attaching a strain gauge to the elastic body 130 and processes the sensing signal through a signal processing circuit formed on the circuit board 153 to act on force and / Or it is possible to measure the torque and transmit and receive the measurement result through wireless communication with a controller (not shown) through the wireless antenna 175.

In one embodiment, the multi-axis force torque sensor 100 may be configured to perform USB communication instead of wireless communication by forming a USB connection port on one side of the lower cover 170 instead of the wireless antenna 175.

2A to 2C are perspective views, partially cut-away perspective views, and a bottom perspective view showing the elastic body in FIG. 1.

In one embodiment, the elastic body 130 is designed with a new structure for effective strain detection and workability. Here, the material of the elastic body 130 may be formed of an aluminum alloy, but is not limited thereto, and may be selected based on elasticity, yield strength, final strength, linearity, mass and workability.

2A to 2C, the elastic body 130 includes an upper plate 210, a lower plate 220, a plurality of beams 230 connecting the upper plate 210 and the lower plate 220, and a plurality of beams 230. It may include a strain gauge 240 attached to each of the multiple points.

In one embodiment, the elastic body 130 has different sizes of the upper plate 210 and the lower plate 220, and as shown in Fig. 2c, one of the upper plate 210 and the lower plate 220 fills the center and the other Silver can be processed into a hollow shape. Here, the upper plate 210 and the lower plate 220 may connect the upper cover 110 and the lower cover 170, respectively.

In one embodiment, the upper plate 210 is formed in a disk shape, and a screw hole 211 is formed on the disk to be attached in surface contact with the upper cover 110 through a screw. The lower plate 220 is formed in a ring shape, and a screw hole 221 is formed on the ring to be attached in direct contact with the lower cover 170. Here, the upper plate 210 may have a relatively small diameter compared to the lower plate 220.

The plurality of beams 230 may be configured of four and disposed between the upper plate 210 and the lower plate 220 to face each other. Here, the plurality of beams 230 is formed as four, but is not limited thereto and may be formed as three. In one embodiment, the plurality of beams 230 connects the upper plate 210 and the lower plate 220 through the first to fourth beams 230a, 230b, 230c, and 230d, so that the surface strain for various forces and moments ( surface strain) can be effectively detected. As shown in FIG. 2C, the plurality of beams 230 may form a T-shaped component through a horizontal member Th and a vertical member Tv extending vertically from the center of the horizontal member Th. Here, the horizontal member Th may be connected between the lower plate 220, and the vertical member Tv may be connected to the upper plate 210 by bending an end portion toward the upper plate 210. At this time, the vertical member Tv may increase the surface strain rate by forming a circular or elliptical groove 231 inside.

The detection point of the surface strain refers to the point of the largest surface strain in the plurality of beams 230. The force acting in the x- or y-axis direction causes a greater deformation of the vertical member Tv of the plurality of beams 230, and the force acting in the z direction causes a greater deformation of the horizontal member Th. In order to obtain a high surface strain value and reduce the overall height of the elastic body 130, the vertical member Tv may include a groove 231 for increasing the stress concentration of the surface of the vertical member Tv at the top.

The strain gauge 240 is distributedly attached to each of the horizontal members Th and the vertical members Tv of the plurality of beams 230 and is configured to detect force and torque by detecting surface strain at multiple points.

3 is a view showing a state in which a strain gauge is attached to horizontal and vertical members of the beam in the elastic body of FIG. 2.

Referring to FIG. 3, all candidate detection points may be designated for each of the plurality of beams 230. Here, the subscript i of Sij represents the beam number (1-4), and the subscript j represents the strain gauge position (1-8). For example, S ₄₁ denotes a detection point of the fourth beam 230d at position 1. In Sij, when the subscript j is 2, 4, 6, the bottom surface point of the horizontal member (Th) of the i-beam is specified.

In one embodiment, the elastic body 130 can attach eight strain gauges to each of the plurality of beams 230 by distributing it, and in the case of the four beams 230, up to 32 strain gauges can be attached, and thus multi-point By properly arranging and attaching the strain gauge 240 at the point where the surface strain rate is high, the number of strain gauges can be reduced and the cost of the sensor can be reduced, and processing becomes easy. It can increase productivity.

4 is a graph showing a change in surface strain according to the thickness of a horizontal member of a beam in the elastic body shown in FIG. 2.

In the graphs shown in (a) to (f) of FIG. 4, according to the force applied to the force torque sensor 100, the horizontal axis represents the thickness of the horizontal member Th of the beam 230, and the vertical axis represents the surface strain. (a) shows that the T-shaped portion of the beam 230 of the elastic body 130 is deformed according to the thickness of the horizontal member Th of the beam 230 when a force of 200N is applied in the x-axis direction. (b) shows that the T-shaped portion of the beam 230 of the elastic body 130 is deformed according to the thickness of the horizontal member Th of the beam 230 when a force of 200N is applied in the y-axis direction, (c) Represents that the T-shaped portion of the beam 230 of the elastic body 130 is deformed according to the thickness of the horizontal member Th of the beam 230 when a force of 200N is applied in the z-axis direction. (d) shows that the T-shaped portion of the beam 230 of the elastic body 130 is deformed according to the thickness of the horizontal member Th of the beam 230 when a torque of 10 Nm is applied to the x-axis. (e) shows that the T-shaped portion of the beam 230 of the elastic body 130 is deformed according to the thickness of the horizontal member Th of the beam 230 when a torque of 10 Nm is applied to the y-axis, (f) Represents that the T-shaped portion of the beam 230 of the elastic body 130 is deformed according to the thickness of the horizontal member Th of the beam 230 when a torque of 10 Nm is applied to the z-axis.

5 is a graph showing the change in surface strain according to the thickness of the vertical member of the beam in the elastic body of FIG. 2.

In the graphs shown in (a) to (f) of FIG. 5, according to the force applied to the force torque sensor 100, the horizontal axis represents the thickness of the vertical member Tv of the beam 230, and the vertical axis represents the surface strain. (a) shows that the T-shaped portion of the beam 230 of the elastic body 130 is deformed when a force of 200N is applied along the x-axis, and (b) is the elastic body 130 when a force of 200N is applied along the x-axis. It indicates that the T-shaped part of the beam 230 is deformed, and (c) is the surface strain detected by the strain gauge 240 attached to the beam 230 of the elastic body 130 when a force of 200N is applied along the z-axis. Represents. (d) shows that the T-shaped portion of the beam 230 of the elastic body 130 is deformed when a torque of 10 Nm is applied to the x-axis, and (e) is the elastic body 130 when a torque of 10 Nm is applied to the y-axis. ) Indicates that the T-shaped portion of the beam 230 is deformed, and (f) is S ₄₃ , S ₁₇ , S ₁₄ , S of the beam 230 of the elastic body 130 when a torque of 10 Nm is applied to the z-axis. ₁₃ , S ₄₁ , S ₄₅ represents the surface strain detected by the strain gauge 240 attached to the point.

The multiaxial force torque sensor 100 according to an embodiment has a high surface strain rate by appropriately adjusting the thickness of the horizontal and vertical members of the beam 230 constituting the elastic body 130, as shown in FIGS. 4 and 5 You can get the value. Here, the thickness of the horizontal member (Th) of the beam 230 may be 1.6 mm, and the thickness of the vertical member (Tv) may be 1.8 mm.

6 is a diagram showing a signal processing configuration formed on the circuit board shown in FIG. 1.

6, the circuit board 153 includes a Wheatstone bridge circuit 310, a first low pass filter 320, a first stage amplifier 330, a zero adjustment circuit 340, and a second low pass filter 350. ), a two-stage amplifier 360 and a microcontroller 370 may be included.

The Wheatstone bridge circuit 310 is connected to the strain gauge 240 distributedly attached to the horizontal and vertical members of the four beams 230 of the elastic body 130 to detect the surface strain. For example, two strain gauges (S ₁ , S ₂ ) and two high-precision resistors (R _b1 , R _b2 ) were used to connect the Wheatstone bridge circuit 310 in the form of a half bridge. For example, when a force is applied to the elastic body 130 and deformed, the surface strain signal of the elastic body 130 is sensed through each strain gauge (S ₁ , S ₂ ) located at the deformation point, and then the Wheatstone bridge circuit 310 is It is output to the first low pass filter (LPF) 320 connected to the rear end through the output terminal.

In one embodiment, the Wheatstone bridge circuit 310 is a full bridge that can be configured using four strain gauges, and five half-bridges composed of two strain gauges and two resistors, and the surface strain from 14 strain gauges 240 By detecting the value, six force components (Fx, Fy, Fz, Mx, My, Mz) can be provided.

The signal output through the Wheatstone bridge circuit 310 is filtered while passing through the first low pass filter 320 and amplified to a predetermined size through the first stage amplifier 330. The output voltage V _u1out of the first stage amplifier 330 may be given by Equation 1 below.

[Equation 1]

가 될 수 있다.Here, V _U1ref is the reference voltage of the first stage amplifier 330 and is generated by the zero adjustment circuit 350,

Can be.

Accordingly, the output voltage V _u1out of the first stage amplifier 330 can be summarized by Equation 2 below.

[Equation 2]

The zero adjustment circuit 340 is a digital potentiometer to amplify the output signal of the Wheatstone bridge circuit 310 under no load and make the offset voltage of the filtered signal to "0 (zero)" And an operational amplifier.

The zero-adjusted signal is processed through the second low-pass filter 350 and the two-stage amplifier 360 in sequence and then transmitted to the microcontroller 370 to obtain force components in three directions and torque components in three directions. .

7 is a graph showing force measurement results for a step-shaped static load (Fz) in the z-axis direction in the strain gauge type multi-axis force torque sensor according to an embodiment of the present invention.

Referring to FIG. 7, when a force acting in the z-axis direction is given, the force torque sensor 100 according to an embodiment shows excellent performance in terms of a connection effect in the Mx component. Similar results were obtained when forces or moments were input from other directions.

8A to 8C are comparative graphs showing force measurement results for dynamic loads in the three (x, y, z) directions in the present invention and the conventional force torque sensor.

In FIGS. 8A to 8C, the performance of the present invention was verified by showing results similar to those of the prior art when looking at the force measurement results for the dynamic load in the three axes of x, y, and z. The maximum difference between the force measurement results between the present invention and the conventional force torque sensor was 1.8%, 2.0%, and 2.0%, respectively.

9 is a graph showing linearity and hysteresis of a strain gauge multi-axis force torque sensor according to an embodiment of the present invention.

In FIG. 9, a total load of 16 kgf was applied in the z-axis direction and then unloaded in stages, and a maximum linearity error of 1.6% was shown in the hysteresis test.

10A to 10C are photographs showing a model actually manufactured of a strain gauge type multi-axis force torque sensor according to an embodiment of the present invention.

10A is a photograph of a developed product of the strain gauge type multi-axis force torque sensor 100 according to an embodiment, and shows a state in which the antenna 175 is mounted on one side of the lower cover 170. In this case, wireless communication can be performed through the USB wireless communication unit.

10B is a multi-axis force torque sensor 100 shown in FIG. 10A by forming a USB connection port on one side of the lower cover 170 instead of the antenna 175 to perform wired communication through USB.

FIG. 10C is an internal picture of the multiaxial force torque sensor 100 shown in FIG. 10A, in which a circuit board (PCB) 153 is interposed in the space between the elastic body 130 and the lower cover 170, and on the circuit board 153 The microcontroller 370 may be mounted on, and the battery 155 may be installed therein.

Although the above has been described with reference to the preferred embodiments of the present application, those skilled in the art will variously modify the present invention within the scope not departing from the spirit and scope of the present invention described in the following claims. And it will be appreciated that it can be changed.

100: strain gauge type multi-axis force torque sensor
110: upper cover 130: elastic body
150: circuit board part 170: lower cover
210: upper plate 220: lower plate
230: a plurality of beams 231: groove
Th: horizontal member Tv: vertical member
240: strain gauge
310: Wheatstone bridge circuit 320,350: low pass filter
330,360: amplifier 340: zero adjustment circuit
370: microcontroller

Claims (10)

Upper cover;
A cylindrical lower cover;
Multi-points for detecting surface strain, including an upper plate fastened to a lower portion of the upper cover, a lower plate having a diameter larger than the upper plate and a plurality of beams connecting between the upper plate and the lower plate, mounted inside the lower cover. An elastic body to form; And
A circuit board part mounted between the lower cover and the elastic body and configured to process analog and digital signals on the surface strain of the elastic body measured through a strain gauge,
Each of the plurality of beams
A horizontal member connected to the lower plate and a vertical member extending vertically from the center of the horizontal member and bent at an end thereof to be connected to the upper plate, wherein a groove is formed inside the vertical member to increase a surface strain. Strain gauge type multi-axis force torque sensor.
The method of claim 1, wherein the elastic body
A plurality of strain gauges that connect the upper plate and the lower plate with three or four beams, and detect the surface strain at a point where the surface strain is high in the T-shaped portion formed through the horizontal member and the vertical member of the beam. Multi-axis force torque sensor of a strain gauge method, characterized in that distributed and attached.
delete The method of claim 1, wherein the elastic body
One of the upper plate and the lower plate is formed in a disk shape to be connected to one of the upper cover and the lower cover by making surface contact, and the other of the upper and lower plates is formed in a ring shape, so that one of the upper cover and the lower cover Multi-axis force torque sensor of the strain gauge method, characterized in that the edge contact and connected with the other.
delete The method of claim 2,
A strain gauge type multi-axial force torque sensor, characterized in that the signal processing circuit board is interposed in one of the space between the upper cover and the elastic body or the space between the lower cover and the elastic body, and fixed to a corresponding cover.
The method of claim 6, wherein the signal processing circuit board
A multi-axis force torque sensor of a strain gauge method, characterized in that a Wheatstone bridge circuit connected to the plurality of strain gauges, an amplifying circuit, a zero point adjustment circuit, a microcontroller, and a communication terminal are installed.
The method of claim 7,
A wireless antenna or USB connection port is formed on one side of the lower cover, and is connected to a communication terminal installed on the signal processing circuit board through the wireless antenna or USB connection port to enable wireless or USB communication. Strain gauge type multi-axis force torque sensor.
The method of claim 6,
A strain gauge type multi-axis force torque sensor, characterized in that a battery is installed in a space between the elastic body and the signal processing circuit board.
Cap-shaped upper cover;
A cylindrical lower cover having a wireless antenna or USB connection port formed on one side thereof;
It is formed of a plate-shaped upper plate fixedly coupled to the upper cover, a ring-shaped lower plate fixedly coupled to the lower cover and having a diameter larger than the diameter of the upper plate, and four beams connecting the upper plate and the lower plate, the four beams Each has a horizontal member connected to the lower plate and a vertical member extending vertically from the center of the horizontal member and bent at an end thereof to be connected to the upper plate, and an elastic body having a circular or elliptical groove formed inside the vertical member; And
A strain gauge attached to each of the four beams to detect surface strain,
The force component and/or torque applied to the x, y, z axes by signal processing a signal processing circuit board interposed on the lower cover and fixed to the lower cover in the space between the lower cover and the elastic body A strain gauge type multi-axis force torque sensor, characterized in that the component is measured and the measurement result is transmitted through wireless communication or USB communication through the wireless antenna or the USB connection port.

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