KR102041710B1 - MultiAxis Force Sensor And MultiAxis Force Sensing System - Google Patents

Abstract

The present invention is composed of a flexible material and the shape of the radial air chamber, by using the material characteristics and geometrical characteristics of the shape to distinguish the force composed of the multi-axial force component applied from the outside in each axial direction is measured Possible multi-axis external force sensor and a multi-axis external force detection system having the same.

Description

Multi-axis external force sensor and multi-axis external force detection system having same {MultiAxis Force Sensor And MultiAxis Force Sensing System}

The present invention relates to a multi-axis external force sensor and a multi-axis external force detection system having the same. More specifically, the present invention is composed of a flexible material and the shape of the radial air chamber, by using the material properties and geometrical characteristics of the shape of the force consisting of the multi-axis force component applied from the outside in each axial direction The present invention relates to a multi-axis external force sensor and a multi-axis external force detection system having the same.

Typical force sensors use strain gauge type load cells. The load cell is a variable resistance type sensor that detects the change in strain caused by external force. Such a load cell has an advantage of high precision, but an additional amplification circuit is required to measure the small voltage change due to strain, and such a load cell is often made of a hard material, and such a load cell is applied to the body. Alternatively, when used as a force sensor mounted to contact the body or skin to measure the force applied by the body, the user has a disadvantage of discomfort and injury due to its rigid material or structure. In particular, recently, a wearable lower limb auxiliary robot has been introduced. In the case of such a wearable lower limb auxiliary robot, sensors are mounted on a shoe or an insole by measuring foot pressure or ground reaction force to determine a walking cycle. Many times.

Meanwhile, various tactile and pressure sensors made of flexible materials have been introduced. It is a method of using resistance value change by external force or bending by embedding liquid metal having variable resistance in soft material. These soft pressure sensors are not suitable for the measurement of plantar pressure or ground reaction force for control information of a wearable robot due to the limitation of measuring only a small force range of about 1N.

The present invention is composed of a flexible material and the shape of the radial air chamber, by using the material characteristics and geometrical characteristics of the shape to distinguish the force composed of the multi-axial force component applied from the outside in each axial direction is measured It is an object of the present invention to provide a multi-axis external force sensor and a multi-axis external force detection system having the same.

In order to solve the above problems, the present invention is a housing of a flexible material; A plurality of mutually separated air chambers provided in the housing; A pressure sensor provided in each of the plurality of air chambers; And an external force distributing member disposed at a plurality of air chamber center positions of the upper surface of the housing to distribute the external force applied from the upper portion of the housing to a predetermined area.

In this case, a pressure sensor provided in each of the air chambers may be disposed at the center of the bottom surface of the air chamber.

In addition, each of the air chambers may be formed with an extension extending toward both adjacent air chambers.

Here, the plurality of air chambers are formed in a cylindrical shape, the extension portion of the air chamber may be formed extending in the direction of the adjacent air chamber at the inner end of each air chamber.

Each of the plurality of extension portions of the air chamber may be configured to form a separate circular arc of one circle in the z-axis cross-sectional direction of the housing.

In this case, the housing is formed in a cylindrical shape, the external force dispersion member may be installed in the center of the upper surface of the housing in the form of a disk.

In this case, the radius of the external force distribution member may be a size from the center of the upper surface of the housing to the extension of the air chamber.

In addition, the plurality of air chambers may be configured in a cylindrical shape.

Here, three air chambers are disposed at intervals of 120 degrees, and the first to third pressure sensors are disposed at the center of the bottom surface of each air chamber, and the first to third pressure sensors are located on the vertex of an equilateral triangle on the xy plane. Can be placed in.

And, when an external force having at least one axial component of the x-axis direction, the y-axis direction and the z-axis direction is applied to the external force dispersion member, the plurality of air chambers are respectively compressed or expanded and deformed, and each air chamber The pressure sensor installed therein may output a positive measurement value or a negative measurement value according to the compression or expansion of each air chamber.

In this case, the internal pressure of the air chamber may be set to be equal to the atmospheric pressure such that the first to third pressure sensors are in a state where no external force is applied to the external force applying member.

In addition, in order to solve the above problems, the present invention is a housing of a flexible material; A plurality of mutually separated air chambers provided in the housing; A pressure sensor provided in each of the plurality of air chambers; An external force dispersing member disposed at a plurality of center positions of the air chambers of the upper surface of the housing to distribute the external force applied from the upper portion of the housing to a predetermined area; And a controller configured to determine an x-axis direction, a y-axis direction, and a z-axis direction component of the external force through the pressure values measured by the pressure sensors by the external force applied to the external force dispersion member. Can be provided.

Here, when an external force having at least one axial component of the x-axis direction, the y-axis direction and the z-axis direction is applied to the external force dispersing member, the plurality of air chambers are respectively compressed or expanded and deformed, and each air chamber The pressure sensor installed therein may output a positive measurement value or a negative measurement value according to the compression or expansion of the air chamber.

In addition, three air chambers are disposed at intervals of 120 degrees, and the first to third pressure sensors are installed at the center of the bottom surface of the air chamber, and the first to third pressure sensors are the second pressure sensor and the third pressure sensor. A base connecting the X axis is parallel to the X axis, and the first pressure sensor is disposed on a vertex of an equilateral triangle on an xy plane disposed above the base,

When the multi-axis external force applied to the external force dispersion member is applied, the x-axis, y-axis and z-axis components (F _x , F _y and F _z ) are measured values S1 _, S ₂ and the first to third pressure sensors. Can be calculated from S ₃₎ and the relationship

- under -

, (또는

)

, (or

)

Where α and β are correlation coefficients

According to the multi-axis external force detection sensor and the multi-axis external force detection system having the same according to the present invention, by using a flexible material for the detection sensor for detecting the multi-axis external force can be used in easy to contact the human body.

In addition, according to the multi-axis external force sensor and the multi-axis external force detection system having the same, according to the present invention, by placing a plurality of air chambers on the same plane to a flat sensor to detect the multi-axis external force in a flat form Since it can be mounted, it can be used for gait analysis or wearable robot control technology.

In addition, according to the multi-axis external force sensor and the multi-axis external force detection system having the same according to the present invention, by converting the pressure measured by using the pneumatic sensor provided in the air chamber provided in the housing of the flexible material converted to external force Simplify configuration and reduce costs.

1 is a plan view and a cross-sectional view of a multi-axis external force sensor according to the present invention.
2 and 3 show a plan view of a deformation state when an external force is applied to the multi-axis external force sensor according to the invention.
Figure 4 shows the pressure measurement value of each pressure sensor constituting the multi-axis external force sensor according to the present invention according to the magnitude of the external force and the measured value of the axial force by the three-axis load cell.
5 is a cross-sectional view of a deformation state when an external force is applied to the multi-axis external force sensor according to the present invention.
6 shows the pressure measurement of each pressure sensor of the multi-axis external force sensor of the present invention according to the magnitude of each axial external force.
Figure 7 shows the relationship between the external force and the external force measured by the multi-axis external force sensor according to the present invention.
8 is a comparison result of applying an external force within a range of 15N or less including a multiaxial component, and measuring an axial external force using the multiaxial external force sensor and the aforementioned three-axis load cell.

Hereinafter, preferred embodiments of the present invention will be described in detail. However, the invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosure may be made thorough and complete, and to fully convey the spirit of the present invention to those skilled in the art. Like numbers refer to like elements throughout. 1 is a plan view and a cross-sectional view of a multi-axis external force sensor 100 according to the present invention.

The multi-axis external force detection system according to the present invention measures the pressure of at least three points by using the multi-axis external force sensor 100 of the new structure to derive the magnitude of the axial force of the external force constituting the multi-axis component, the multi-axis external force detection The controller constituting the system uses a method of deriving the magnitude of the axial force of the external force constituting the multiaxial component. Hereinafter, the multi-axis external force sensor 100 will be described.

Multiaxial external force sensor 100 according to the present invention is a housing 10 of a flexible material; A plurality of air chambers 20 separated from each other provided in the housing 10; A pressure sensor 30 provided in each of the plurality of air chambers 20; And an external force dispersing member 40 disposed at a center position of the plurality of air chambers 20 of the upper surface of the housing 10 to distribute the external force applied from the upper portion of the housing 10 to a predetermined area. Can be.

In the embodiment shown in Figure 1, the housing 10 is formed of a flat cylindrical shape and the housing 10 may be made of a flexible material such as silicon or rubber.

A plurality of air chambers 20 may be provided in the housing 10. Each air chamber 20 may be configured to be partitioned with each other in the housing (10). Preferably, the air chamber 20 is provided with three or more.

As shown in FIG. 1 (a), the pressure sensors 30 are embedded in the plurality of air chambers 20 arranged in a radial manner with a flexible material. The three sensors are arranged at intervals of 120 degrees on the same circumference, and can use this geometric characteristic to measure multiaxial external forces as described below. The pressure sensor 30 may be a pneumatic sensor or the like.

As shown in FIG. 1 (b), the pressure sensor 30 provided in each air chamber 20 may be attached to a bottom surface of each air chamber 20.

Each of the air chambers 20 may be basically cylindrical, but as shown in FIG. 1 (a), the air chambers 20 are formed in an arc shape toward the adjacent air chambers 20. The unit 21 may be provided.

In FIG. 1, each air chamber 20 is spaced apart in a triangular shape but extends in an arc shape inside each air chamber 20 so that axial components of the external force are well dispersed to the adjacent air chamber 20. The unit 21 can be configured. Each extension 21 may be configured to be disposed on the circumference of one circle. In this case, each of the extension parts 21 of the plurality of air chambers 20 may form a separate circular arc of one circle in the z-axis cross-sectional direction of the housing 10.

The embodiment shown in Figure 1 is configured in the form that the extension portion 21 is provided in the cylindrical air chamber 20, the shape can be changed in various ways.

In addition, in order to distribute the external force applied from the upper portion of the housing 10 to a predetermined area, the external force dispersing member 40 disposed at the center positions of the plurality of air chambers 20 of the upper surface of the housing 10 may be further provided. have.

The external force dispersion member 40 is to allow the external force applied from the outside to be dispersed in three directions, that is, each air chamber 20.

The external force distribution member 40 may be configured in the form of a plate and is not limited to the disc form as shown in FIG.

Since the housing 10 is made of a flexible material, in order to measure the axial external force by the external force to induce a pressure change inside the air chamber 20, even if the area to which the external force is applied, the respective air chamber 20 It should be possible to distribute

Therefore, the bottom surface of the external force dispersion member 40 may have a structure extending to the upper portion of each of the air chamber 20.

In the embodiment shown in FIG. 1, the external force dispersing member 40 does not extend to the circular regions of the three air chambers 20, but is configured to cover a portion of the extension 21 to the external force dispersing member 40. When an external force is applied to the upper portion, the force may be uniformly distributed to each air chamber 20 according to the direction of the external force.

2 and 3 illustrate a plan view of a deformation state when an external force is applied to the multi-axis external force sensor 100 according to the present invention.

Specifically, FIG. 2 (a) shows a plan view of the deformation state of the multi-axis external force sensor when the -y axial external force (-F _y ) is applied, and FIG. 2 (b) shows the external force (+ F _x ) on the + x axis direction. ) Is a plan view of the deformation state of the multi-axis external force sensor 100 when the () is applied, Figure 3 (a) is a multi-axis external force sensor when the + z-axis (down) direction external force (+ F _z ) is applied 3 (b) shows the deformation state of the multi-axis external force sensor 100 when the external force F is applied in the [-x-axis direction, + y-axis direction, and + z-axis direction]. A plan view is shown.

In each case, the housing 10 of the flexible material is deformed in the opposite direction of the external force by the external force applied thereto, and increases the pressure inside the air chamber 20 in the deforming direction so that the pressure sensor 30 detects the changed pressure. Can be configured.

In the case of the multi-axis external force sensor 100 according to the present invention, the internal pressure inside each of the three sealed air chambers 20 and the atmospheric pressure outside the housing 10 coincide with each other when no external force is applied. desirable.

Generally, in order to decompose the force in the form of a vector into the x-axis, y-axis, and z-axis, each of the axial sensors must be provided. We use the method of deriving the y- and z-axis forces.

For example, in the case of FIG. 2 (a) to which the -y axial external force (-F _y ) is applied, the external force almost causes an increase in the pressure of the pressure sensor 30 inside the first air chamber 20a, but FIG. In the case of 2 (b), 3 (a) and 3 (c), a pressure change of at least two or more pressure sensors 30 may be generated by an external force applied thereto.

Figure 4 shows the pressure measurement value of each pressure sensor 30 constituting the multi-axis external force sensor 100 according to the present invention according to the magnitude of the external force and the measured value of the axial force by the three-axis load cell.

Specifically, Figure 4 (a) is a first pressure provided in the first air chamber 20a to the third air chamber 20c provided in the multi-axis external force sensor 100 according to the present invention when an external force is applied The pressure measurement values by the sensors 30a to the third pressure sensor 30c are shown, and FIG. 4 (b) shows the external force applied to the multi-axis external force sensor 100 of the present invention in three axial directions (x, y, z) Results measured using a load cell (USL08-H6 from TechGihan) are shown.

In the test process, the axial shear force in the x-axis direction or the y-axis direction is mainly applied in the interval of 0 to 23 seconds, and considering the direction of the shear force and the reference direction of the pressure sensor 30, etc. The first pressure sensor 30a to the third pressure sensor 30c disposed in a triangle of the external force sensor 100 may confirm that a pressure change of the pressure sensor 30 is mainly affected.

In addition, in the same section, it can be seen that the force measured by the load cell in the three axis directions (x, y, z) also has a similar trend and can be measured.

However, in the section exceeding 23 seconds, a complex external force with a complex force direction was applied, and the pressure and force linearity measured by the pressure sensor 30 and the multi-axis external force sensor 100 of the multi-axis external force sensor 100 were applied in the section. It can be seen that the correlation or pattern becomes difficult to find.

5 is a cross-sectional view of a deformation state when an external force is applied to the multi-axis external force sensor 100 according to the present invention.

Specifically, FIG. 5A illustrates a case where no external force is applied, FIG. 5B illustrates a case where an external force F _z is applied in the + z-axis direction, and FIG. 5C illustrates + x. The case where the axial external force F _x is applied is shown, and FIG. 5 (d) shows the case where the + x-axis and + z-axis direction external forces F _x are applied.

When the external force applied to the external force dispersion member 40 includes a component of the z-axis force, the volume of the air chamber 20 is reduced as shown in FIGS. When the external force including the component of the force in the x-axis direction or the y-axis direction is applied, causing an increase in pressure of the pressure sensor 30 provided in the air chamber 20, the multi-axis external force sensor 100 according to the present invention Since the pressure sensor 30 is arranged in an equilateral triangle, it is confirmed that the sum of the increase and decrease values of the pressure is constant due to the geometrical characteristics of the pressure sensor 30 array.

When an external force having at least one axial component of the x-axis direction, the y-axis direction, and the z-axis direction is applied to the multi-axis external force sensor 100 according to the present invention, each of the plurality of air chambers 20 is compressed or The expansion and deformation of the pressure sensor 30 installed in each air chamber 20 may output a positive measurement value or a negative measurement value according to the compression or expansion of the air chamber 20.

The linear relationship with the magnitude of the axial force of the external force including the multi-axial component through each pressure value measured by the plurality of pressure sensors 30 measured by the multi-axis external force sensor 100 according to the present invention Since it cannot be derived, the multi-axis external force sensing system according to the present invention derives the magnitude of the axial force of the external force including the multi-axis component by using each pressure value through the control unit. Explain the specific method.

FIG. 6 shows the pressure measurement of each pressure sensor 30 of the multi-axis external force sensor 100 of the present invention according to the magnitude of each axial external force.

Three air chambers 20 constituting the multi-axis external force sensor 100 according to the present invention are disposed at intervals of 120 degrees, and the first to third pressure sensors 30c are installed at the center of the bottom surface of the air chamber 20. The first to third pressure sensors 30c may have a bottom side connecting the second pressure sensor 30 and the third pressure sensor 30c to be parallel to the X axis, and the first pressure sensor 30a may be formed in the first to third pressure sensors 30c. It is disposed on the vertex of the equilateral triangle on the xy plane disposed on the base side.

The control unit of the multi-axis external force detection system according to the present invention calculates as follows by using the measured values of the multi-axis external force sensor 100 according to the present invention described above, the x-axis, y-axis and z-axis direction components of the multi-axis external force (F _x , F _y and F _z ) can be derived.

That is, the first pressure sensor 30a to the third pressure sensor 30c as the x-axis external force F _x , the y-axis external force F _y , and the z-axis external force F _z are applied. It can be seen that the relationship between the pressure measurement values P (30a), P (30b) and P (30c) measured at has a linear pattern as shown in FIG.

Therefore, when the multi-axis external force including the x-axis, y-axis and / or y-axis component is applied to the multi-axis external force sensor 100 according to the present invention, the x-axis, y-axis and z-axis direction component (F) of the multi-axis external force _x , F _y and F _z ) are measured values S _1, S ₂ and the first to third pressure sensors 30c. S ₃ ) and the following relationship can be seen.

Here, the pressure measurement values P (30a), P (30b) and P (30c) measured by the first pressure sensor (30a) to the third pressure sensor (30c) are represented by S _1, S ₂ and S _{3 ,} respectively. , α and β can be determined experimentally by correlation coefficient.

-Formula 1-

, (또는

)

, (or

)

In addition, the x-axis of the multi-axis external force pressure measurement values S _1, S ₂ and S ₃ of the first pressure sensor 30a to the third pressure sensor 30c measured by the multi-axis external force sensor 100 according to the present invention , y- and z-axis components (F _x , F _y, and The value of each row and column of the above transformation matrix for conversion to F _z ) may be calculated by the values of α and β determined experimentally, or the alignment of the air chamber 20 or the pressure sensor 30 or Since a deviation from the calculated value may be generated according to the volume of the air chamber 20 of the air chamber 20, the value of each row and column constituting the conversion matrix may be finely adjusted by using a measured value such as a load cell.

In addition, the multiaxial external force sensor 100 according to the present invention assumes that the air chamber 20 and the pressure sensor 30 are arranged in an equilateral triangle, so that the above conversion matrix is determined, the air chamber 20 and the pressure sensor ( In case of changing the arrangement of 30), the above transformation matrix can be changed.

7 illustrates a relationship between an external force and an external force measured through the multi-axis external force sensor 100 according to the present invention.

That is, the horizontal axis of FIG. 7 is the magnitude of the axial external force measured by the load cell, and the vertical axis is the pressure measured values S _1, S _2, and the first pressure sensor 30a to the third pressure sensor 30c. Using S ₃ , the magnitude of the axial external force calculated from the first equation above is shown.

The red reference line is a reference line when the magnitude of the external force measured by the load cell and the magnitude of the external force for each axis calculated through the first equation are the same, and the calculation result is measured by the first pressure sensor 30a to the third pressure sensor 30c. Using the pressure measurement values S _1, S _2, and S ₃ , the magnitude of the external force measured by the load cell and the magnitude of the external force measured by the load cell are generally coincident with each other, and thus, the first pressure sensors 30a to 3rd. The pressure measured values S _1, S _2, and S ₃ measured by the pressure sensor 30c can be calculated using the first equation above to determine the magnitude of the x-axis y-axis and z-axis force of the multi-axis external force including the multi-axis component. It can be confirmed.

8 is a comparison result of applying an external force within a range of 15N or less including a multiaxial component and measuring the axial external force using the multiaxial external force sensor 100 and the above-described three-axis load cell according to the present invention.

As a result of the comparison, when an external force including a multiaxial component is applied, the first equation is used for each axial external force measured using a three-axis load cell and the pressure value measured through the multiaxial external force sensor 100 of the present invention. The root mean square error (RMSE) of the axial external force, the y-axis external force, and the z-axis external force of the magnitudes of the axial external force derived from the test results was only 0.2N, 0.23N, and 0.5N.

Although the present specification has been described with reference to preferred embodiments of the invention, those skilled in the art may variously modify and change the invention without departing from the spirit and scope of the invention as set forth in the claims set forth below. It could be done. Therefore, it should be seen that all modifications included in the technical scope of the present invention are basically included in the scope of the claims of the present invention.

1000: multi-axis external force sensor
20: air chamber
30: pressure sensor
40: external force dispersion member

Claims (14)

Housing of flexible material;
Cylindrical first to third air chambers separated from each other and sealed in the housing and disposed at intervals of 120 degrees;
First to third pressure sensors respectively provided at centers of bottom surfaces of the air chambers;
An external force dispersing member disposed at a plurality of center positions of the air chambers of the upper surface of the housing to distribute the external force applied from the upper portion of the housing to a predetermined area; And,
And a controller configured to determine an x-axis direction, a y-axis direction, and a z-axis direction component of the external force through pressure values measured by the pressure sensors by the external force applied to the external force dispersion member.
Each said air chamber has an extension configured in the form of a separate arc towards the adjacent air chamber,
When the external force is applied to the upper portion of the external force dispersion member in order to distribute the force uniformly to each air chamber according to the direction of the external force, the external force dispersion member is configured in the form of a disc covering a size covering a portion of the extension,
The internal pressure of the air chamber is set equal to the atmospheric pressure so as to be the first to third pressure sensors in a state where no external force is applied to the external force dispersion member.
When an external force having an axial component of at least one of an x-axis direction, a y-axis direction and a z-axis direction is applied to the external force dispersing member, the plurality of air chambers are respectively compressed or expanded and installed in each air chamber. The pressure sensor is a multi-axis external force sensing system, characterized in that for outputting a positive or negative measurement value in accordance with the compression or expansion of the air chamber. The method of claim 1,
The first to third pressure sensors are disposed on a vertex of an equilateral triangle on an xy plane in which a bottom side connecting the second pressure sensor and the third pressure sensor is parallel to the X axis, and the first pressure sensor is disposed on the bottom side. ,
When the multi-axis external force applied to the external force dispersion member is applied, the x-axis, y-axis and z-axis components (F _x , F _y and F _z ) are measured values S _1, S ₂ and the first to third pressure sensors. S ₃ ) and the geometry of the multi-axis external force sensing system, characterized in that calculated from the following relationship.
- under -

, (or

)
* Where α and β are experimentally determined correlation coefficients The method of claim 1,
The housing is a multi-axis external force sensing system, characterized in that configured in the form of a cylinder. delete delete delete delete delete delete delete delete delete delete delete

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