KR20160084031A - Method for measuring 6-axis force using a hydraulic touch sensor - Google Patents

Abstract

A six-axis force measuring method using a fluid-type tactile sensor including a fluid tactile sensor including a fluid inside the touch pad, the touch pad being deformed when the fluid touches the object, and the measuring unit photographing the deformed shape of the touch pad, Information about the shape of the touch pad, and information about the pressure acting on the touch pad. The touch pad is divided into a minute surface area. The force balance equations are applied to each of the divided minute surfaces to calculate the left and right force acting on each fine surface, respectively. The forces in the X, Y, and Z axes at the respective minute facets are calculated from the forces in the left and right and upward and downward directions acting on the respective minute facets. The forces in the X, Y, and Z axes at the respective minute facets are summed to calculate the forces in the X, Y, and Z axes acting on the entire touch pad.

Description

METHOD FOR MEASURING 6-AXIS FORCE USING A HYDRAULIC TOUCH SENSOR [0002]

The present invention relates to a six-axis force measuring method, and more particularly, to a six-axis force measuring method using a fluid tactile sensor for measuring a six-axis force applied to the touch pad using a fluid tactile sensor including a touch pad .

In order to precisely control a robot or a manipulator, it is necessary to measure an external force acting between a workpiece and a robot or a manipulator. Generally, an end effector or end effector of a robot or a manipulator has a three- A measurement sensor capable of measuring a six-axis force including a moment is provided, and the external force is measured.

Korean Patent Application No. 10-2011-0036967 discloses a technology for measuring the six-axis force of the end of such a robot or a manipulator. In Korean Patent Application No. 10-2011-0036967, an arithmetic processing unit for performing a calculation of a six- And the like.

In addition, in the case of most conventional six-axis force measurement, a strain gauge or the like is included to provide a measurement sensor for directly measuring force and moment, and as described in Korean Patent Application No. 10-2011-0036967, It is common in measurement technology to include measurement sensors for directly measuring force / moment.

However, recently, in the development of robots for gripping objects, there has been an increasing technical demand for manufacturing grip parts of robots using soft flexible materials such as human fingers. Accordingly, while grasping objects with a flexible material, There is a growing need for a six-axis force measurement technique.

Nevertheless, there is a technical limitation in applying the measuring technique of the six-axis force using the conventional measuring sensor to the manufacture of the grip portion of the flexible material. Thus, while manufacturing the grip portion of the flexible material, a separate measuring sensor is omitted, It is required to develop a technique capable of measuring the temperature of the liquid.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a six-axis force measuring method capable of precisely measuring six-axis force using a fluid tactile sensor and omitting a separate measuring sensor.

In the 6-axis force measuring method using the fluid tactile sensor according to one embodiment for realizing the object of the present invention, information about the shape of the touch pad photographed by the measuring unit, information about the pressure acting on the touch pad . The touch pad is divided into a minute surface area. The force balance equations are applied to each of the divided minute surfaces to calculate the left and right force acting on each fine surface, respectively. The forces in the X, Y, and Z axes at the respective minute facets are calculated from the forces in the left and right and upward and downward directions acting on the respective minute facets. The forces in the X, Y, and Z axes at the respective minute facets are summed to calculate the forces in the X, Y, and Z axes acting on the entire touch pad.

In one embodiment, in the step of calculating the left and right vertical force acting on each fine face,

식 (2)

Equation (2)

(F _l : leftward force acting on fine face, F _r : rightward force acting on fine face, F _u : upward force acting on fine face, F _d : downward force acting on fine face, p : Pressure acting on fine cotton, S: area of fine cotton)

The force equilibrium equation of the above equation (2) can be applied.

In one embodiment, the force equilibrium equation of equation (2)

식 (6)

Equation (6)

식 (7)

Equation (7)

식 (8)

Equation (8)

( _x , _y) is an angle formed by the tangential direction of the minute surface in the XY plane and the X axis, and θ _z is an angle formed by the tangential direction of the fine surface in the XZ plane and the X axis, S _x : Area in the X-axis direction of the fine cotton, S _y : area in the Y-axis direction of the fine cotton, S _z : area in the Z-axis direction of the fine cotton)

(6) to (8) as the components in the X, Y, and Z-axis directions at the respective minute facets.

In one embodiment, the component in the X-axis direction in the micro face of the formula (6)

식 (9)

Equation (9)

식 (10)

Equation (10)

Equation (9) can be used if the minute surface area corresponds to the first and second quadrants in the XY plane, and Equation (10) can be used if it corresponds to the third and fourth quadrants.

In one embodiment, the component in the Y-axis direction in the micro face of the formula (7)

식 (11)

Equation (11)

식 (12)

Equation (12)

Equation (11) can be used if the minute surface is in the first and fourth quadrants in the XY plane, and Equation (12) can be used if it is in the second and third quadrants.

In one embodiment, the component in the Z-axis direction at the micro face of the equation (8)

식 (13)

Equation (13)

식 (14)

Equation (14)

The above equations (13) and (14) can be used.

In one embodiment, a moment balance equation is applied to each of the divided minute surfaces so as to calculate respective moments in the left and right and upward and downward directions acting on the respective fine surface areas, Calculating a moment in the X, Y, and Z-axis directions at each fine surface from the moment in the up-and-down direction, and summing moments in the X, Y, and Z- And calculating a moment in the X, Y, and Z axial directions.

According to the embodiments of the present invention, since the six-axis force acting on the touch pad can be calculated when the touch pad is in contact with the object through the touch pad including the fluid, if the conventional electronic / mechanical sensor for calculating the six- It is also possible to calculate the axial force. Thus, in a situation such as grasping a product using a robot, the grip portion of the robot can be replaced by a touch pad including a fluid, thereby realizing a mechanism similar to that of an actual human being grasping a product, It is possible to control to apply the optimum force and moment.

In particular, after calculating the force or moment acting on the minute surface by the force or moment equilibrium equation after dividing the touch pad into a minute surface area, a six-axis force acting on the entire touch pad is calculated. Conventionally, The six-axis force acting on the touch pad can be calculated without performing displacement measurement of the side end portion through marking such as an edge marker on the portion.

That is, without measuring tension or force information acting on the end portion of the touch pad, only the information about the pressure applied to the entire touch pad, the shape and area of the touch pad, The six-axis force applied to the rotor can be calculated.

1 is a perspective view illustrating a fluid tactile sensor used in a six-axis force measuring method according to an embodiment of the present invention.
2 is a flowchart illustrating a six-axis force measuring method according to an embodiment of the present invention.
FIG. 3 is a schematic diagram showing a state where an object is in contact with a touch pad of the fluid tactile sensor of FIG. 1. FIG.
Fig. 4 is a schematic diagram showing a state in which the touch pad is divided into minute facets in Fig. 2. Fig.
FIG. 5 is a schematic diagram for deriving the equilibrium equation at each fine surface in FIG.
Fig. 6 is a schematic diagram showing forces acting on the respective fine surface areas in Fig. 2 on the XY plane.
Fig. 7 is a schematic diagram showing forces acting on the respective minute surface areas of Fig. 2 on the XZ plane.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing. The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms.

The terms are used only for the purpose of distinguishing one component from another. The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise.

In the present application, the term "comprises" or "comprising ", etc. is intended to specify that there is a stated feature, figure, step, operation, component, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view illustrating a fluid tactile sensor used in a six-axis force measuring method according to an embodiment of the present invention.

Referring to FIG. 1, the fluid tactile sensor 10 used in the six-axis force measuring method according to the present embodiment includes a body 100, a touch pad 110, a measuring unit 130, an image processing unit 140, And a calculation unit 150. [

The body part 100 forms a storage space 1 therein and the measurement part 130 is located in the storage space 1. [

The touch pad unit 110 includes a plate portion 111 and a touch pad 112 and is fixed to a lower portion of the body portion 100. The plate portion 111 separates the storage space 1 of the body portion 100 from the touch pad 112 and a fluid is sealed inside the touch pad 112.

Since the touch pad 112 is formed of a material having a predetermined elastic force and the fluid is sealed inside the touch pad 112, the shape of the touch pad 112 is deformed when the object 1 contacts the outer surface.

Particularly, since the interior of the touch pad 112 is filled with fluid, the touch pad 112 is pressed in the outward direction by the fluid. Accordingly, when the object 1 contacts the outer surface and the fluid receives a pressure larger than the pressure externally applied, the shape of the touch pad 112 is deformed.

The measurement unit 130 photographs the deformed shape of the touch pad 112. For this purpose, a pair of cameras 131 and 132 are arranged to face the touch pad 112. [ In this case, the measuring unit 130 may include only one camera, or may photograph a deformed shape of the touch pad 112 in a stereo manner when the camera includes a pair of cameras.

In this way, the information about the deformed shape of the touch pad photographed by the measuring unit 130 is provided to the image processing unit 140, and the photographed data is processed to derive the deformed shape of the touch pad.

The calculation unit 150 includes an information input unit 151 and an operation unit 152. The information input unit 151 inputs information about the shape of the touch pad to the operation unit 152, And the like.

When the touch pad contacts the object 1 based on information about the shape of the touch pad provided from the information input unit 151 and information about the pressure applied to the touch pad, The six-axis force acting on the touch pad is measured.

Hereinafter, the six-axis force measuring method in the calculating section 152 will be described in detail.

2 is a flowchart illustrating a six-axis force measuring method according to an embodiment of the present invention. FIG. 3 is a schematic diagram showing a state where an object is in contact with a touch pad of the fluid tactile sensor of FIG. 1. FIG. Fig. 4 is a schematic diagram showing a state in which the touch pad is divided into minute facets in Fig. 2. Fig. FIG. 5 is a schematic diagram for deriving the equilibrium equation at each fine surface in FIG. Fig. 6 is a schematic diagram showing forces acting on the respective fine surface areas in Fig. 2 on the XY plane. Fig. 7 is a schematic diagram showing forces acting on the respective minute surface areas of Fig. 2 on the XZ plane.

2 and 3, the operation unit 152 receives the touch pad 112 from the information input unit 151 and displays the touch pad 112 in a deformed shape as the object 1 touches the touch pad 112 Information about the pressure p received by the touch pad 112 by the fluid S filled in the touch pad 112 and the shape S of the touch pad 112 before deformation of the touch pad 112, (Step S10).

3, the pressure applied to the bottom of the touch pad by the fluid 1 and the pressure applied to the bottom of the touch pad 112 by the object 1 are measured with respect to a horizontal base of the touch pad 112, Is defined as a force applied to the base of the touch pad 112. The force balance equation is expressed by the following equation (1).

식 (1)

Equation (1)

2 and 4, the touch pad 112 is divided into minute areas as shown in FIG. 4 (step S20). In this case, when the touch pad 112 is divided into m lines in the Z-axis direction, forces (F ₁ , F ₂ , F ₃ ,. ..., F _{m -2} , F _{m -1} , F _m ), it is possible to calculate the resultant force in the Z-axis direction acting on the touch pad 112.

An arbitrary minute surface area of the touch pad 112 thus divided is shown in Fig.

Next, referring to FIGS. 2 and 5, F _r , F _l , F _u , and F _d are calculated by applying a force equilibrium equation to each of the fine surfaces (step S30).

In this case, F _r , F _l , F _u , and F _d are forces in the right direction, force in the left direction, force in the upper direction, Direction, the area of the fine pattern area is represented by S, and the pressure acting on the fine pattern area is represented by P.

That is, when the force equilibrium equation of the following equation (1) is applied to the micro face, it is described as the following equation (2).

식 (2)

Equation (2)

Fig. 6 is a diagram showing a micro pattern on an arbitrary XY plane, and when a force equilibrium equation is described on an XY plane with respect to the arbitrary fine pattern, the equation (2) is expressed by the following equations (3) and Can be expressed.

In this case, (i, j) cell is a corresponding micro-scale to which the equilibrium equations are applied, and (i, j + 1) do. Accordingly, θ _{xy (i, j)} is the XY plane corresponding smile myeonso (i, j) of one end of the cell is defined as a tangential direction and the X axis and the _{angle, θ xy (i, j +} 1) are XY on the Is defined as the angle formed by the tangential direction of one end of the (i, j + 1) cell adjacent to the (i, j) cell on the plane and the X axis.

식 (3)

Equation (3)

식 (4)

Equation (4)

Fig. 7 is a diagram showing a micro-pattern on an arbitrary XZ plane. When a force equilibrium equation is described on an XZ plane with respect to the arbitrary fine pattern, the equation (2) can be expressed by the following equation (5) .

Similarly, θ _{z (i, j)} is defined as an angle formed by the tangential direction of one end of the corresponding fine surface (i, j) cell on the XZ plane and the X axis _, Is defined as the angle formed by the tangential direction of one end of the (i, j + 1) cell adjacent to the (i, j) cell of the phase and the X axis.

식 (5)

Equation (5)

Expressions (6), (7), and (8) below are expressed more specifically as the X-axis, Y-axis, and Z- .

식 (6)

Equation (6)

식 (7)

Equation (7)

식 (8)

Equation (8)

In this case, S _x corresponds to the area in the X-axis direction of the corresponding micro face, S _y corresponds to the area in the Y-axis direction of the corresponding micro face, and S _z corresponds to the area in the Z axis direction of the corresponding micro face.

(9), and if the corresponding fine pattern is in the third and fourth quadrants in the XY plane, the equation (6) .

식 (9)

Equation (9)

식 (10)

Equation (10)

Equation (7) can be expressed as Equation (11) if the corresponding fine surface is in the first and fourth quadrants in the XY plane, and Equation (12) is obtained if the corresponding fine surface is in the second and third quadrants in the XY plane. Is modified.

식 (11)

Equation (11)

식 (12)

Equation (12)

Further, the component in the Z-axis direction at the corresponding fine surface of the equation (8) is corrected to the equation (13) in consideration of the directionality, and further, F _r , F _l , F _u , F _d Lt; / RTI >

식 (13)

Equation (13)

식 (14)

Equation (14)

As described above, F _r , F _l , F _u , and F _d in the corresponding small surface area (i, j) cell can be calculated using the above equations (9) to (14). That is, it is possible to calculate all of the forces in the four directions acting on the fine surface.

When the forces F _r , F _l , F _u , and F _d in the four directions acting on the fine surface are calculated, the forces F _r , F _l , F _u , and F _d F _x , F _y , and F _z obtained by converting the X, Y, and Z axes to the X, Y, and Z axis directions (step S40).

Thereafter, all the F _x , F _y , and F _z in the X axis, Y axis, and Z axis directions calculated in the respective fine face areas are summed (step S50) The force exerted on the elastic member 112 can be measured. Further, the direction and size of the force acting on the entire touch pad 112 can be calculated through the resultant force of the forces in the X-axis, Y-axis, and Z-axis directions.

As described above, in this embodiment, a marker such as an edge marker is used for the touch pad 112 to measure the displacement of the side surface of the touch pad 112, or information about the force acting on the side surface of the touch pad 112 By dividing the touch pad 112 into a plurality of minute areas on the basis of the information about the deformed shape of the touch pad 112 and the pressure applied to the touch pad 112 without inputting the touch, The force acting on the pad 112 can be calculated.

Meanwhile, the direction and the magnitude of the moment acting on the entire touch pad 112 can be calculated in the same manner as described above, and moments in the X-axis, Y-axis, and Z- The pressure of the touch pad 112 and the pressure applied to the touch pad 112 in the same manner as the method of measuring the force in the Z-axis direction, Can be calculated.

3, the fluid is generated by the pressure applied to the bottom of the touch pad by the object 1 with respect to the horizontal base of the touch pad 112 And a moment generated by a force applied to a corner portion of the touch pad 112 is defined as a moment applied to a base of the touch pad 112 and is expressed by a moment balance equation balance equation, the above equation (1) is transformed into the following equation (15).

식 (15)

Equation (15)

That is, the moment balance equation is applied to each of the minute surface areas divided by the minute surface area of the touch pad 112 to calculate moments in the X, Y, and Z axis directions at the corresponding minute surface areas, It is possible to measure the moments in the X, Y, and Z axial directions that act on the entire pad 112.

Thus, it is possible to measure the six-axis force acting on the touch pad 112 by measuring both the force and the moment in the X, Y, and Z axis directions.

When the six-axis force measurement using the touch pad is applied to a finger or the like of a robot holding an object, the finger portion of the robot is made of a fluid tactile sensor including a touch pad, To the finger portion of the robot so that an optimal six-axis force for accurately grasping an actual object can be applied to the finger portion of the robot.

Particularly, since the fluid tactile sensor does not require a sensor unit including a separate electronic / mechanical element, the fluid tactile sensor can be miniaturized and precisely applied. Therefore, the fluid tactile sensor can be applied to a medical robot or the like to provide an optimal force for gripping objects, As shown in FIG.

According to the present embodiment, since the six-axis force acting on the touch pad can be calculated when the touch pad is in contact with the object through the touch pad including the fluid, if the conventional electronic / mechanical sensor for calculating the six- It is also possible to calculate the axial force. Thus, in a situation such as grasping a product using a robot, the grip portion of the robot can be replaced by a touch pad including a fluid, thereby realizing a mechanism similar to that of an actual human being grasping a product, It is possible to control to apply the optimum force and moment.

In particular, after calculating the force or moment acting on the minute surface by the force or moment equilibrium equation after dividing the touch pad into a minute surface area, a six-axis force acting on the entire touch pad is calculated. Conventionally, The six-axis force acting on the touch pad can be calculated without performing displacement measurement of the side end portion through marking such as an edge marker on the portion.

That is, without measuring tension or force information acting on the end portion of the touch pad, only the information about the pressure applied to the entire touch pad, the shape and area of the touch pad, The six-axis force applied to the rotor can be calculated.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims. It can be understood that it is possible.

The six-axis force measuring method using the fluid tactile sensor according to the present invention has industrial applicability that can be used for robots that hold objects with a finger.

10: fluid tactile sensor 1: object
100: body part 110: touch pad part
111: plate portion 112: touch pad
130: measuring unit 140: image processing unit
150: Calculator 151: Information input unit
152:

Claims (7)

A six-axis force measuring method using a fluid tactile sensor including a touch pad deformed when an object is in contact with a fluid and a measuring unit for photographing a deformed shape of the touch pad,
Information about a shape of the touch pad photographed by the measuring unit, and information about a pressure applied to the touch pad;
Dividing the touch pad into minute facets;
A force balance equation is applied to each of the subdivided areas to thereby calculate left and right and upward and downward forces acting on the respective minute facets;
Calculating force in the X, Y, and Z axial directions at the respective fine surface areas from the lateral force and the vertical force acting on each of the fine surface areas; And
And calculating a force in the X, Y, and Z axis directions acting on the entirety of the touch pad by summing the forces in the X, Y, and Z axis directions at the respective fine surface areas. Way. 2. The method according to claim 1, wherein, in the step of calculating the forces acting in the left and right direction and the up and down direction acting on the respective minute facets,

Equation (2)
(F _l : leftward force acting on fine face, F _r : rightward force acting on fine face, F _u : upward force acting on fine face, F _d : downward force acting on fine face, p : Pressure acting on fine cotton, S: area of fine cotton)
Wherein the force equilibrium equation of the formula (2) is applied. 3. The method according to claim 2, wherein the force equilibrium equation of the equation (2)

Equation (6)

Equation (7)

Equation (8)
( _x , _y) is an angle formed by the tangential direction of the minute surface in the XY plane and the X axis, and θ _z is an angle formed by the tangential direction of the fine surface in the XZ plane and the X axis, S _x : Area in the X-axis direction of the fine cotton, S _y : area in the Y-axis direction of the fine cotton, S _z : area in the Z-axis direction of the fine cotton)
(6) to (8) as the components in the X, Y, and Z-axis directions at the respective minute surface areas, respectively. 4. The method according to claim 3, wherein the component in the X-axis direction in the micro face of the formula (6)

Equation (9)

Equation (10)
(10) is used if the minute surface area corresponds to the first and second quadrants in the XY plane, and the equation (10) is used in the third and fourth quadrants. The method according to claim 3, characterized in that the component in the Y-axis direction in the micro face of the formula (7)

Equation (11)

Equation (12)
(11) if the minute surface is in the first and fourth quadrants in the XY plane, and (12) is used in the second and third quadrants. 4. The method according to claim 3, wherein the component in the Z-axis direction in the micropattern of the formula (8)

Equation (13)

Equation (14)
A method for measuring a six-axis force using a fluid tactile sensor, wherein the equation (13) and the equation (14) are used. The method according to claim 1,
Calculating moments in left and right and upward and downward directions acting on the respective minute facets by applying a moment balance equation to each of the divided fine facets;
Calculating moments in the X, Y and Z axes at the respective fine surface areas from the moments in the left and right and up and down directions acting on the respective fine surface areas; And
And calculating a moment in the X, Y, and Z axial directions acting on the entire touch pad by summing the moments in the X, Y, and Z axial directions at the respective minute surface areas. How to measure.

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