WO2021039600A1

WO2021039600A1 - Tactile sensor element, tactile sensor, triaxial tactile sensor, and tactile sensor element manufacturing method

Info

Publication number: WO2021039600A1
Application number: PCT/JP2020/031521
Authority: WO
Inventors: 和彦笹川
Original assignee: 国立大学法人弘前大学
Priority date: 2019-08-28
Filing date: 2020-08-20
Publication date: 2021-03-04
Also published as: JPWO2021039600A1; JP7466214B2

Abstract

Provided are a tactile sensor element, and the like, that make it possible to reduce tactile sensor thickness, measure with a high degree of accuracy by enhancing measurement stability under low stress, and manufacture with a high degree of consistency by reducing differences between individual units in production.　The cross-sectional structure of a tactile sensor element (10) comprises a lower electrode (12), a PEDOT:PSS stress reception layer (14) formed so as to extend over one end side (12r) of the lower electrode (12), and an upper electrode (16) formed on the stress reception layer (14). These components are laminated in close contact. The tactile sensor element (10) is manufactured using a lamination process. When sheer stress is applied in the horizontal direction to the upper electrode (16), a planar overlapping area S where the lower electrode (12) and upper electrode (16) overlap in the vertical direction via the stress reception layer (14) shrinks or grows according to the orientation of the sheer stress, and as a result, the electrical resistance value between the upper electrode (16) and lower electrode (12) increases or decreases. Thus, it is possible to measure the sheer stress applied to the tactile sensor element (10) on the basis of the relationship between the variation in the electrical resistance value and the sheer stress.

Description

Manufacturing method of tactile sensor element, tactile sensor, 3-axis tactile sensor and tactile sensor element

The present invention is a tactile sensor having a structure in which a pair of lower electrodes, a stress-sensitive layer formed straddling the pair of lower electrodes, and an upper electrode formed on the stress-sensitive layer are laminated. The present invention relates to a tactile sensor in which two tactile sensor elements are arranged to face each other on a plane, a three-axis tactile sensor in which two tactile sensors are arranged along two axes on a plane, and the like.

A conventional pressure-sensitive sensor is known to have a structure in which two electrodes are opposed to each other and a conductive layer or a resin layer is sandwiched between them. The pressure-sensitive sensor detects a physical quantity between electrodes (for example, an electric resistance value between electrodes) that changes when the conductive layer or resin layer is deformed by an applied force as pressure or shear stress.

In Patent Document 1, a conductor (consisting of a material in which silver particles are dispersed in a resin such as polyester) and a resistor are formed on the first substrate, and the conductor and the resistor are formed on the second substrate. Is formed, and a pressure sensitive device is disclosed in which both substrates are brought into contact with each other to face each other. When a load is applied to this pressure sensitive device, both substrates bend and the force that presses the two resistors increases, and the contact area of both resistors increases and the contact resistance decreases, so the output resistance value Decreases. The pressure sensitive device of Patent Document 1 can be said to be a resistance type pressure sensitive sensor.

Patent Document 2 discloses a tactile sensor having a configuration in which a pair of electrodes are attached to a magnetic rubber body. By changing the contact state between the tactile sensor and the object to be inspected, a force (shear stress, shear stress, etc.) from the object to be inspected is applied to the magnetic rubber body, and the amount of current between the pair of electrodes changes. This amount of current is detected to detect the object to be inspected.

In order to detect pressure and shear stress by the pressure sensor or tactile sensor disclosed in

Patent Document

1 or 2 described above, a force detection layer such as a conductor or a magnetic rubber body between opposing electrodes is in the direction of force. It is necessary to have enough room for deformation. That is, the larger the amount of deformation before and after the application of stress, the better the stress can be detected. Therefore, it is better that the detection layer is easily deformed. In order to make the same material easily deformable, it is necessary to increase the thickness of the detection layer. There is a problem that this hinders the realization of thinning of the pressure sensor or the tactile sensor.
In addition to the pressure-sensitive sensor described above, there is also an example in which a tactile sensor is formed by applying a conductive polymer to two electrodes and bonding them together. However, since both electrodes are not in contact (close contact), the reaction under low stress (when the horizontal deformation under shear stress is small, etc.) is unstable, and measurement is difficult. there were. Further, the sensor has a problem that individual differences in fabrication are large and it is difficult to suppress variations.

Japanese Patent No. 3664622 Japanese Unexamined Patent Publication No. 2013-232293

As described above, in the pressure-sensitive sensor or tactile sensor disclosed in

Patent Document

1 or 2, the thickness of the force detection layer of the conductor, magnetic rubber body, etc. is an important factor, and therefore the pressure-sensitive sensor or tactile sensor There was a problem that it hindered the realization of thinning.

In the tactile sensor in which a conductive polymer is applied to the above-mentioned two electrodes and they are bonded together, the reaction under low stress is unstable because the two electrodes are not in contact (adhesion), and the measurement can be performed. There was a problem that it was difficult. Further, the sensor has a problem that individual differences in fabrication are large and it is difficult to suppress variations.

Therefore, an object of the present invention has been made to solve the above problems, and to provide a tactile sensor element, a tactile sensor, a three-axis tactile sensor, and the like capable of reducing the thickness of a pressure sensor or a tactile sensor. There is.

A second object of the present invention is a tactile sensor element that improves measurement stability under low stress to enable highly sensitive measurement, reduces individual differences in fabrication, and enables production with suppressed variation. , A tactile sensor, a 3-axis tactile sensor, and the like.

In the tactile sensor element of the present invention, a pair of lower electrodes, a stress-sensitive layer formed straddling each one end side of the pair of lower electrodes, and an upper electrode formed on the stress-sensitive layer are respectively. It is a tactile sensor element having a structure in which the pair of lower electrodes are closely laminated, and has a region on a plane where the lower electrode and the upper electrode overlap in the vertical direction on each one end side of the pair of lower electrodes. When a contact pressure is applied to the tactile sensor element in the vertical direction, the stress-sensitive layer is compressed to reduce the electrical resistance between both electrodes (the upper electrode and the lower electrode), and the tactile sensor element is in the horizontal direction. When a shear stress is applied to the electrodes, the electrical resistance between the two electrodes increases in the direction in which the overlapping region decreases, and the electrical resistance between the two electrodes decreases in the direction in which the overlapping region increases. It is a feature.

The tactile sensor of the present invention is a tactile sensor in which two tactile sensor elements of the present invention are arranged on one axis (for example, x-axis) of the xy plane with the one end sides of the pair of lower electrodes facing each other. When a contact pressure is applied to the tactile sensor in the vertical direction and / or a shear stress is applied in the horizontal direction, the contact pressure and / or the shear stress is detected based on the change in the electric resistance of each tactile sensor element. It is characterized by that.

Here, in the tactile sensor of the present invention, the tactile sensor is in contact with the electric resistance of the first tactile sensor element (first sensor resistance) and the electric resistance of the second tactile sensor element (second sensor resistance). A bridge circuit is constructed based on the first sensor resistance and the second sensor resistance (fixed resistance) when no pressure and shear stress are applied. The first sensor resistance and the fixed resistance are arranged, the second sensor resistance and the fixed resistance are arranged on the other opposite sides, and the input voltage is applied to the branch point between the first sensor resistance and the second sensor resistance. The amount of change in the resistance value of the first sensor resistance (first sensor resistance value) and the resistance value of the second sensor resistance (second sensor resistance value) depends on the contact pressure applied to the tactile sensor, the shear stress, and the ambient temperature. Given, the amount of change in the first sensor resistance value due to shear stress and the amount of change in the second sensor resistance value are equal in absolute value (referred to as "the amount of change in sensor resistance value due to shear stress") and are in contact with each other. The amount of change in the first sensor resistance value due to pressure and the amount of change in the second sensor resistance value (referred to as "amount of change in sensor resistance value due to contact pressure") can be equal.

Here, in the tactile sensor of the present invention, when a contact pressure and a shear stress are applied to the tactile sensor, the measured potential with respect to the grounding of the branch point in the one opposite side and the grounding of the branch point in the other opposite side Based on the principle that the potential difference from the measured potential is obtained by the amount of change in the sensor resistance value due to the shear stress, the input voltage, and the resistance value of the fixed resistance, the amount of change in the sensor resistance value due to the shear stress is calculated. It can be obtained by removing the contact pressure and the ambient temperature.

Here, in the tactile sensor of the present invention, when contact pressure and shear stress are applied to the tactile sensor, the measured potential with respect to the ground contact of the branch point in the one opposite side and the ground contact of the branch point in the other opposite side. Based on the principle that the sum potential with the measured potential is obtained by the amount of change in the sensor resistance value due to the contact pressure, the input voltage, and the resistance value of the fixed resistance, the amount of change in the sensor resistance value due to the contact pressure is calculated. It can be obtained by removing the shear stress and the ambient temperature.

The 3-axis tactile sensor of the present invention is a 3-axis tactile sensor in which two tactile sensors of the present invention are arranged along two axes on a plane, and a contact pressure is applied to the three-axis tactile sensor in a vertical direction. When shear stress is applied in the horizontal direction and / or in the horizontal direction, the contact pressure and / or shear stress is detected based on the change in the electric resistance value of each tactile sensor element.

The 3-axis tactile sensor of the present invention is a 3-axis tactile sensor in which two tactile sensors of the present invention are arranged along two axes (xy axes) on a plane, and the three-axis tactile sensor is located on the x-axis. An xy-axis bridge circuit is constructed by combining the x-axis bridge circuit composed of the arranged tactile sensors and the y-axis bridge circuit composed of the y-axis tactile sensors in parallel, and the sensor resistance of each sensor resistance of the x-axis bridge circuit is formed. It is characterized in that an input voltage is commonly applied to the branch point and the branch point of each sensor resistance of the y-axis bridge circuit.

The method for manufacturing a tactile sensor element of the present invention is formed by a lower electrode forming step of printing a pair of lower electrodes with a metal (preferably silver) ink on a predetermined base film and a lower electrode forming step. A metal (a metal () is placed on the stress-sensitive layer forming step of forming a stress-sensitive layer by applying a predetermined conductive polymer over the pair of lower electrodes and the stress-sensitive layer formed in the stress-sensitive layer forming step. It is characterized by comprising an upper electrode forming step of printing a preferably silver) ink to form an upper electrode.

The cross-sectional structure of the tactile sensor element of the present invention comprises a lower electrode, a stress-sensitive layer of a conductive polymer or the like (for example, PEDOT / PSS) formed straddling one end side of the lower electrode, and a stress-sensitive layer. It is composed of an upper electrode formed in. On one end side of the lower electrode, the lower electrode and the upper electrode have a vertically overlapping region (overlapping region) (via a stress-sensitive layer) on a plane. When a horizontal shear stress is applied to the upper electrode of the tactile sensor element, the overlapping region decreases or increases depending on the horizontal orientation, which increases or decreases the electric resistance value between the upper electrode and the lower electrode. To do. Therefore, the shear stress applied to the tactile sensor element can be measured based on the relationship between the change in the electric resistance value and the shear stress. When a contact pressure is applied to the tactile sensor element in the vertical direction, the stress-sensitive layer is compressed and the electrical resistance between the upper electrode and the lower electrode is reduced. Therefore, there is an effect that the contact pressure applied to the tactile sensor element can be measured based on the relationship between the change in the electric resistance value and the contact pressure.

Since the tactile sensor element is manufactured using a stacking process, it is possible to reduce the thickness of the tactile sensor by using the tactile sensor element, and it is possible to reduce individual differences in manufacturing and suppress variation. effective. The lower electrode and the stress-sensitive layer of the tactile sensor element, and the stress-sensitive layer and the upper electrode each have a structure in which they are closely laminated. Therefore, the tactile sensor element has an effect of improving measurement stability even under low stress and enabling highly sensitive measurement.

The tactile sensor was arranged symmetrically on a plane, left and right, with a pair of lower electrodes of the tactile sensor element and a pair of lower electrodes of another tactile sensor element facing each other. When a horizontal shear stress is applied to the upper electrode of the tactile sensor element, the overlapping region decreases or increases depending on the horizontal orientation, which increases or decreases the electric resistance value between the upper electrode and the lower electrode. To do. On the other hand, when the same shear stress is applied to the upper electrode of another tactile sensor element in the horizontal direction, the decrease or increase of the overlapping region is opposite to that of the previous tactile sensor element, and therefore, between the upper electrode and the lower electrode. The increase or decrease of the electric resistance value of is opposite to that of the tactile sensor element. Therefore, by subtracting the change of each electric resistance value of one set of tactile sensor elements, there is an effect that the left and right (X-axis direction) shear stress applied to the tactile sensor can be detected.

The tactile sensor can be configured with a bridge circuit. According to the shear stress detection principle used in the present invention, there is an effect that the amount of change in resistance value due to shear stress can be obtained by removing the contact pressure and the ambient temperature. According to the contact pressure detection principle used in the present invention, there is an effect that the amount of change in the resistance value due to the contact pressure can be obtained by removing the shear stress and the ambient temperature.

A 3-axis tactile sensor was manufactured by arranging two tactile sensors along two axes on the (XY) plane. When a contact pressure is applied vertically to the tactile sensor and / or a shear stress is applied in the horizontal direction, the contact pressure and / or the shear stress is detected based on the change in the electric resistance value of the tactile sensor element. Can be done.

In the 3-axis tactile sensor of the present invention, the stress-sensitive layer responsible for sensing and the upper electrode and the lower electrode are brought into close contact with each other by stacking, and a dedicated measurement principle is devised. As a result, the tactile sensor is made thinner because the thickness of the detection layer is thin while the stress detection layer has room to be sufficiently deformed in the direction of stress, and the measurement stability is improved even under low stress for highly sensitive measurement. There is an effect that it is possible to provide a 3-axis tactile sensor capable of providing a sensor.

It is sectional drawing which shows the structure of the tactile sensor element 10 of this invention. It is a perspective view of the tactile sensor element 10 of this invention. It is a figure which shows the photograph and structure of PEDOT / PSS which is an example of a conductive polymer. It is a figure which shows the tactile sensor 20 which arranged two tactile sensor elements 10 (tactile sensor elements 10 and 10'), (XY) plane. It is a circuit diagram which configured the tactile sensor 20 shown in FIG. 4 by a bridge circuit 30. It is a figure which shows the three-axis tactile sensor 40 which arranged two tactile sensors 20 (

tactile sensor

20 and 20Y'), and arranged along two axes on the (XY) plane. FIG. 6 is a circuit diagram in which the 3-axis tactile sensor 40 shown in FIG. 6 is composed of a bridge circuit 50. It is a figure which photographed the 3-axis tactile sensor 40. It is a figure which shows typically the calibration device 60 of the 3-axis tactile sensor 40. It is a figure which shows the material tester used for the calibration test of a contact pressure. It is a partially enlarged view of the material testing machine shown in FIG. It is a graph which shows the result of the calibration experiment of contact pressure. It is a graph which shows the result of the calibration experiment when shear stress was applied under the contact pressure of 4 kPa (weight 64). It is a graph which shows the result of the calibration experiment when shear stress was applied under the contact pressure (weight 64) changed to 2kPa and 4kPa.

Hereinafter, examples will be described in detail with reference to the drawings.

FIG. 1 shows a cross-sectional structure of the tactile sensor element 10 of the present invention. In FIG. 1, reference numeral 12 is a lower electrode, and 14 is a stress-sensitive layer such as a conductive polymer formed straddling one end side 12r (right side in FIG. 1) of the lower electrode 12 (having electrical conductivity as described later). ), 16 is an upper electrode formed on the stress-sensitive layer 14. As shown in FIG. 1, the lower electrode 12 and the stress-sensitive layer 14, and the stress-sensitive layer 14 and the upper electrode 16 each have a structure in which they are closely laminated. In addition, on one end side 12r of the lower electrode 12, a region (overlapping region shown by a solid line S; on a plane) in which the lower electrode 12 and the upper electrode 16 vertically overlap (via the stress sensitive layer 14) on a plane. It has a substantially rectangular shape.). When a voltage is applied to the tactile sensor element 10, the current path changes from the current C1 in the lower electrode 12 to the current C2 passing through the stress-sensitive layer 14 as shown in FIG. 1, and the current C3 flowing through the upper electrode 16 (depth direction). ).

FIG. 2 shows a perspective view of the tactile sensor element 10. In FIG. 2, the parts having the same reference numerals as those in FIG. 1 indicate the same elements, and thus the description thereof will be omitted. As shown in FIG. 2, the lower electrode of the tactile sensor element 10 is composed of a pair of

lower electrodes

12a and 12b. This is provided for measuring the electric resistance value of the tactile sensor element 10 as described later. The stress-sensitive layer 14 is formed so as to straddle (bridge) the one end side 12ra of the pair of lower electrodes 12a and the one end side 12rb of the lower electrode 12b. However, in the one end side 12ra, similarly to the one end side 12r shown in FIG. 1, a region (shown in FIG. 1) in which the lower electrode 12a and the upper electrode 16 overlap in the vertical direction (via the stress sensitive layer 14) on a plane. It has the same overlapping region as the solid line S). Similarly, in the case of 12 rb on one end side, a region (overlapping region similar to the solid line S shown in FIG. 1) in which the lower electrode 12b and the upper electrode 16 vertically overlap (via the stress sensitive layer 14) is formed on a plane. Have. Therefore, as shown in FIG. 2, the current path becomes the current C2 passing through the stress-sensitive layer 14 from the current C1 in the lower electrode 12a, then the current C3 flowing through the upper electrode 16, and the current C4 flowing through the stress-sensitive layer 14. The current C5 flows through the lower electrode 12b.

With reference to FIGS. 1 and 2, when a shear stress Fr (from left to right in the figure) is applied horizontally to the upper electrode 16 of the tactile sensor element 10, the overlapping region S decreases and the upper electrode 16 and the lower electrode 12 The electrical resistance value between and increases. On the other hand, when a shear stress Fl (from right to left in the figure) is applied to the upper electrode 16 of the tactile sensor element 10 in the horizontal direction, the overlapping region S increases and the electric resistance value between the upper electrode 16 and the lower electrode 12 increases. Decrease. Therefore, the shear stress applied to the tactile sensor element 10 can be measured based on the relationship between the change in the electric resistance value and the shear stress.

The stress-sensitive layer 14 is a converter (such as a conductive polymer) for the contact pressure and shear stress applied to the tactile sensor element 10, and is polyethylenedioxythiophene (PEDOT) and polystyrene sulfonate (PSS) acid. Dispersion was used. Specifically, PEDOT / PSS manufactured by Orgacon (registered trademark) EL-P3040 and Agfa (registered trademark) -Material was used. FIG. 3 (A) shows a photograph of PEDOT / PSS, which is an example of a conductive polymer, and FIG. 3 (B) shows its structure. PEDOT / PSS has electrical conductivity because many electrons in the molecule move freely on the π orbit. Furthermore, it is known that when compressive stress is applied, it has the property of reducing electrical resistance. Therefore, when a contact pressure is applied to the tactile sensor element 10 in the vertical direction, the stress-sensitive layer 14 is compressed and the electrical resistance between the upper electrode 16 and the lower electrode 12 is reduced. Therefore, the contact pressure applied to the tactile sensor element 10 can be measured based on the relationship between the change in the electric resistance value and the contact pressure. The stress-sensitive layer 14 is not limited to PEDOT / PSS as long as it is a conductive polymer or the like. In the following, PEDOT / PSS will be described as an example.

Next, a method of manufacturing the tactile sensor element 10 will be described. The tactile sensor element 10 is manufactured by using a laminating step. The pair of

lower electrodes

12a and 12b were printed on a substrate (predetermined base film) with a metal ink (HARIMA Chemical Group, NPS-J) using an inkjet printer (CLUSTER TECHNOLOGY and Deskviewer) (lower). Electrode forming step). As the metal ink, for example, silver ink is suitable. In the following, silver ink will be taken as an example, but the metal ink is not limited to silver ink. As the substrate, a special film for silver ink (MITSUBISHI (registered trademark) PAPER MILLS LIMITED, NB-WF-3GF100) was used. The lower electrode 12 was printed on the special film and then appropriately annealed by an electric furnace. The electric conductivity of the silver ink is about ^{6.30 × 10 7 (S / m} ), much greater than the potential conductivity of PEDOT / PSS.

Subsequently, a conductive polymer (for example, PEDOT / PSS: a predetermined conductive polymer) is applied over the surfaces of the pair of

lower electrodes

12a and 12b formed in the lower electrode forming step by a screen printing method (for example, the above-mentioned PEDOT / PSS: a predetermined conductive polymer). By coating), the stress-sensitive layer 14 was formed (stress-sensitive layer forming step). It was coated with multiple layers to reduce the possibility of silver ink getting into PEDOT / PSS. When one layer of PEDOT / PSS was coated, it was appropriately annealed by an electric furnace. After coating all layers, they were appropriately annealed in an electric furnace.

The upper electrode 16 was formed by printing on the stress-sensitive layer (PEDOT / PSS) formed in the stress-sensitive layer forming step by using an inkjet printer using silver ink (upper electrode forming step). The upper electrode 16 was formed while observing the flying state and the dripping state of the silver ink. In order to avoid sending silver ink into PEDOT / PSS, printing was performed while heating appropriately. After printing the upper electrode 16, it was appropriately annealed by an electric furnace. After printing the upper electrode 16 on the surface of PEDOT / PSS with silver ink, it was confirmed that the upper electrode 16 had a specified size and did not spread laterally. Finally, the surface of the tactile sensor element 10 was coated with a polyethylene film for electrical insulation and protection.

Based on the above, according to the first embodiment of the present invention, the cross-sectional structure of the tactile sensor element 10 of the present invention is the stress of the lower electrode 12 and the PEDOT / PSS formed across one end side 12r of the lower electrode 12. It is composed of a sensitive layer and an upper electrode 16 formed on the stress sensitive layer 14. When a horizontal shear stress Fr or Fl is applied to the upper electrode 16 of the tactile sensor element 10, the overlapping region S decreases or increases depending on the horizontal orientation, thereby between the upper electrode 16 and the lower electrode 12. The electrical resistance value of is increased or decreased. Therefore, the shear stress applied to the tactile sensor element 10 can be measured based on the relationship between the change in the electric resistance value and the shear stress. When a contact pressure is applied to the tactile sensor element 10 in the vertical direction, the stress-sensitive layer 14 is compressed and the electrical resistance between the upper electrode 16 and the lower electrode 12 is reduced. Therefore, the contact pressure applied to the tactile sensor element 10 can be measured based on the relationship between the change in the electric resistance value and the contact pressure.

As described above, since the tactile sensor element 10 is manufactured by using the stacking process, the tactile sensor element 10 can be used to reduce the thickness of the tactile sensor, and the individual differences in the manufacturing can be reduced to suppress the variation. It has the effect of enabling manufacturing. The lower electrode 12 and the stress-sensitive layer 14 of the tactile sensor element 10, and the stress-sensitive layer 14 and the upper electrode 16 each have a structure in which they are closely laminated. Therefore, the tactile sensor element 10 has an effect of improving measurement stability even under low stress and enabling highly sensitive measurement.

FIG. 4 shows a tactile sensor 20 in which two tactile sensor elements 10 (tactile sensor elements 10 and 10') described above are arranged on one axis (X axis) on an XY plane. In FIG. 4, the parts having the same reference numerals as those in FIG. 1 indicate the same elements, and thus the description thereof will be omitted. Although only the X-axis and the Z-axis are shown in FIG. 4 for convenience of explanation, the Y-axis is the same as the direction shown in FIG. 6 described later. Each element on the tactile sensor element 10'side is indicated by adding a dash (') to each corresponding element on the tactile sensor element 10'side. As shown in FIG. 4, the tactile sensor 20 includes a pair of

lower electrodes

12a and 12b of the tactile sensor element 10 on each end side 12ra and 12rb, and a pair of lower electrodes 12a'and 12b'of the tactile sensor element 10'. One end side 12ra'and 12rb' were placed to face each other and along one axis (X axis) on a plane. That is, the pair of

lower electrodes

12a, 12b, etc. of the tactile sensor elements 10 and the like are opposed to each other and arranged symmetrically to the left and right (on the X-axis). The electrical resistance value between the

lower electrode

12a and 12b _{R X1,} the electric resistance value between the lower electrode 12a 'and 12b' was _{R X2.} The tactile sensor element 10 _DG shown in FIG. 4 is a dummy gauge (for temperature compensation) whose electrical resistance value changes only by a change in ambient temperature. Each element on the tactile sensor element 10 _DG side is indicated by adding a symbol DG to each corresponding element on the tactile sensor element 10 side. _RDG is an electrical resistance value for temperature compensation.

As described above, when shear stress is applied to the tactile sensor element 10 in the horizontal direction (X-axis direction), the overlapping region S decreases or increases depending on the horizontal direction, and is between the upper electrode 16 and the lower electrode 12a and the like. The electrical resistance value of is increased or decreased. The same applies to the tactile sensor 20 shown in FIG. 4. When a shear stress Fr (from left to right in the figure) is applied to the upper electrode 16 of the tactile sensor element 10 in the horizontal direction, the overlapping region S decreases and the upper electrode _{The electrical resistance value RX1} between 16 and the lower electrode 12a increases. On the other hand, in the case of the tactile sensor element 10', when the same shear stress Fr is applied to the upper electrode 16'in the horizontal direction, the overlapping region S'increases and the electrical resistance value between the upper electrode 16' and the lower electrode 12a'etc. _RX2 decreases. Similarly, in the reverse direction, when a shear stress Fl (from right to left in the figure) is applied to the upper electrode 16 of the tactile sensor element 10 in the horizontal direction, the overlapping region S increases and is between the upper electrode 16 and the lower electrode 12a and the like. The electrical resistance value _{RX1 of} is decreased. On the other hand, in the case of the tactile sensor element 10', when the same shear stress Fl is applied to the upper electrode 16'in the horizontal direction, the overlapping region S'decreases and the electrical resistance value between the upper electrode 16' and the lower electrode 12a'etc. _RX2 increases. Therefore, by subtracting one set of the change of the change and R _X2 of each electric resistance value R _X1 of the tactile sensor element 10 and 10 ', right and left applied to the tactile sensor 20 (the X-axis direction) shear stress Fr , Fl can be detected.

As described above, when a contact pressure is applied to the tactile sensor element 10 in the vertical direction (Z-axis direction), the stress-sensitive layer 14 is compressed and the electrical resistance between the upper electrode 16 and the lower electrode 12a and the like is reduced. To do. Therefore, the contact pressure applied to the tactile sensor element 10 can be measured based on the relationship between the change in the electric resistance value and the contact pressure. Similarly, in the case of the tactile sensor 20 shown in FIG. 4, when a contact pressure is applied to the tactile sensor 20 in the vertical direction, the stress-sensitive layers 14 and 14'are compressed to have electrical resistance values _RX1 and _RX2 . Decreases. Therefore, the contact pressure applied to the tactile sensor 20 can be measured based on the relationship between the change in the electric resistance value and the contact pressure. From the above, when the contact pressure is applied to the tactile sensor 20 in the vertical direction and / or when the shear stresses Fr and Fl are applied in the horizontal direction, the electric resistance values _RX1 and R of the tactile sensor elements 10 and 10'are each. _{Contact pressure and / or shear stress Fr, Fl can be detected based on the change of X2} (“A and / or B” is an abbreviation for “A and B” and “A or B”. It is.).

Hereinafter, the principle of detecting shear stress and contact pressure used in the present invention will be described in detail. FIG. 5 is a circuit diagram in which the tactile sensor 20 shown in FIG. 4 is composed of a bridge circuit 30. In FIG. 5, the parts having the same reference numerals as those in FIG. 4 indicate the same elements, and thus the description thereof will be omitted. As shown in FIG. 5, the tactile sensor 20 includes the electric resistance _RX1 (first sensor resistance) of the tactile sensor element 10 (first tactile sensor element) and the tactile sensor element 10'(second tactile sensor element). the electrical resistance _{R X2} (second sensor resistance) of), the contact pressure and shear stress is a bridge circuit 30 based on the electrical resistance _{R X1} and _R X2 (= R. fixed resistor) when no load. The bridge circuit 30 also includes a series circuit of a fixed resistance R and the electrical resistance _{R DG} dummy gage _{10 DG.} Each resistance value is a resistance value when the bridge circuit 30 is in an equilibrium state. As shown in FIG. 5, the electric resistance R _X1 and the fixed resistor R is disposed on one of opposite sides of the bridge circuit 30, are arranged electrical resistance R _X2 and the fixed resistor R is other opposite sides, the electric resistance R _X1 The input voltage E is applied between the branch point r connecting the electric resistance R _X2 and the electric resistance R _{DG and the ground.} e _1x is the measured potential between the branch point a and the ground, e _2x is the measured potential between the branch point b and the ground, and e ₃ is the measured potential between the branch point g and the ground. If when the contact pressure in the direction perpendicular to the tactile sensor 20 is applied and horizontal shear stresses Fr, Fl is applied, the change e _x of the voltage due to shear stress is given by Equation 1 below.

Here, when the formula 1 is expanded by Taylor, it becomes the formula 2.

Variation [Delta] R _X1 of the electric resistance _{R X1,} variation [Delta] R _X2 of the electrical resistance _{R X2,} the amount of change due to the contact pressure applied to the tactile sensor _{_{20 (ΔR X1CP, ΔR X2CP)}} , the amount of change due to the shear stress (ΔR _X1SS, ΔR _X2SS ) and the amount of change due to ambient temperature (ΔR _{X1 TMP} , ΔR _{X2 TMP} ). The amount of change in the electrical resistance R _DG is given by the amount of change due to the ambient temperature (ΔR _DGTMP). That is, it is given as in Equation 3.

ΔR _X1 = ΔR _X1CP + ΔR _X1SS + ΔR _X1TMP
ΔR _X2 = ΔR _X2CP + ΔR _X2SS + ΔR _X2TMP
ΔR _DG = ΔR _RGTMP (3)

Ignoring the second term of Equation 2 and substituting Equation 3, it becomes Equation 4.

here,
Amount of change due to contact pressure ΔR _X1CP = ΔR _X2CP = ΔR _CP (<0),
The amount of change due to shear stress ΔR _X1SS = −ΔR _X2SS , and the absolute values of both are ΔR _SS ,
Weight change due to ambient temperature _{_{_{ΔR X1TMP = ΔR X2TMP = ΔR TMP}}} (5)
Then, Equation 4 becomes Equation 6.

Based on the above, the shear stress detection principle used in the present invention is as follows. That is, when the contact pressure and shear stress to the tactile sensor 20 is applied, the measured potential e _1x to ground branch point a in one opposite side (electric抵値R _X1 and fixed抵値R are arranged side) , the potential e _x of the difference between the measured potential e _2x to ground branch point b in the other opposite sides (electric抵値R _X2 and fixed抵値R are arranged side) includes a change amount [Delta] R _SS by shear stress The principle is that it is obtained by the input voltage E and the fixed shear value R. Potential e _x is the difference in the actual value, the input voltage E and the fixed resistor R for a constant value, based on the equation 6, to remove the amount of change [Delta] R _SS the contact pressure and the ambient temperature of the resistance value due to the shear stress Can be obtained.

Next, when a contact pressure is applied to the tactile sensor 20 in the vertical direction and when shear stresses Fr and Fl are applied in the horizontal direction, the change in voltage due to the contact pressure of the tactile sensor element 10 e _Z1 is expressed by the following equation 7 Given in.

Here, when the formula 7 is expanded by Taylor and the quadratic term is taken, it becomes the formula 8.

Ignoring the second term of Equation 8 and considering the relationship between Equation 3 and Equation 5, it becomes Equation 9.

_{Similarly, the voltage change eZ2} due to the contact pressure of the tactile sensor element 10'is given by the following equation 10.

From Equation 9 and 10, the change e _Z voltage by contact pressure of the tactile sensor element 10 and 10 'is given by the following equation 11.

Here, considering the relationship of the formula 5, the formula 11 becomes the formula 12.

When the change in the electric resistance value due to the ambient temperature is small and can be ignored (e _1x , e _2x >> e ₃ ), Equation 11 may be expressed as Equation 13.

From the above, the contact pressure detection principle used in the present invention is as follows. That is, when contact pressure and shear stress are applied to the tactile sensor 20, the _{measured potential e 1x} and the dummy gauge with respect to the grounding of the branch point a _{in one opposite side (the side on which the electric resistance RX1 and the fixed resistance R are arranged)} The difference e _{Z1 from the} _{measured potential e 3} with respect to the grounding of the branch point g in the opposite side (the side where the electric resistance R _DG and the fixed resistance R are arranged) including the other opposite side (the electric resistance R _X2 and the fixed resistance R) potential e _Z of the sum of the difference e _Z2 between the measured potential e _2x the measured potential e ₃ to ground branching point g in opposite sides including a dummy gauge for grounding the branch point b of the deployed side) in the contact The principle is that the amount of change due to pressure ΔR _CP , the input voltage E, and the fixed resistance R are obtained. Since the potential e _Z is the sum of the measured values and the input voltage E and the fixed resistance R are constant values, the amount of change in the resistance value due to the contact pressure ΔR _CP is used as the shear stress and the ambient temperature based on the equation 12 or 13. It can be obtained by removing it. When the change in the electric resistance value due to the ambient temperature is small and can be ignored, the potential e _Z may be obtained by the sum of the measured potential e _1x and the measured potential e _2x _{, ignoring the measured potential e 3 on the dummy gauge side.} ..

Based on the above, according to the second embodiment of the present invention, the tactile sensor 20 faces the pair of

lower electrodes

12a and 12b of the tactile sensor element 10 and the pair of lower electrodes 12a'and 12b'of the tactile sensor element 10'. They were arranged symmetrically on the plane. When a shear stress Fr or Fl is applied to the upper electrode 16 of the tactile sensor element 10 in the horizontal direction, the overlapping region S decreases or increases according to the horizontal orientation, whereby the upper electrode 16 and the lower electrode 12a and the like are formed. The electrical resistance value _RX1 between them increases or decreases. On the other hand, when the same shear stress Fr or Fl is applied to the upper electrode 16'of the tactile sensor element 10'in the horizontal direction, the decrease or increase of the overlapping region S'is opposite to that of the tactile sensor element 10, and therefore, the upper electrode _{The increase or decrease of the electric resistance value RX2} between 16'and the lower electrode 12a'etc. is opposite to that of the tactile sensor element 10. Therefore, by subtracting one set of the change of the change and R _X2 of each electric resistance value R _X1 of the tactile sensor element 10 and 10 ', right and left applied to the tactile sensor 20 (the X-axis direction) shear stress Fr , Fl can be detected. Since the tactile sensor element 10 constituting the tactile sensor 20 is manufactured by using a stacking process, it is possible to reduce the thickness of the tactile sensor by using the tactile sensor 20, and to reduce individual differences in manufacturing and suppress variations. It has the effect of enabling manufacturing. The lower electrode 12a and the like of the tactile sensor element 10 constituting the tactile sensor 20, the stress-sensitive layer 14, and the stress-sensitive layer 14 and the upper electrode 16 each have a structure in which they are closely laminated. Therefore, the tactile sensor 20 has the effect of improving measurement stability even under low stress and enabling highly sensitive measurement.

The tactile sensor 20 can be configured by the bridge circuit 30. The principle of detecting shear stress used in the present invention is as follows. That is, when the contact pressure and shear stress to the tactile sensor 20 is applied, the measured potential e _1x to ground the branching point a of the bridge circuit 30, the difference in potential e _x between the measured potential e _2x to ground branch point b Is the principle obtained by the amount of change ΔR _SS due to shear stress, the input voltage E, and the fixed resistance R. Potential e _x is the difference in the actual value, the input voltage E and the fixed resistor R for a constant value, based on the equation 6, to remove the amount of change [Delta] R _SS the contact pressure and the ambient temperature of the resistance value due to the shear stress It has the effect of being able to obtain it. The contact pressure detection principle used in the present invention is as follows. That is, when contact pressure and shear stress are applied to the tactile sensor 20, the difference e _Z1 _{between the measured potential e 1x} _{with respect to the grounding of the branch point a of the bridge circuit 30 and the measured potential e 3} with respect to the grounding of the branch point g, and branching. _{The difference between the measured potential e 2x} with respect to the grounding of the point b and the _{measured potential e 3} with respect to the grounding of the branch point g e _{The potential e Z} of the sum of _Z2 _{is the amount of change ΔR CP} due to the contact pressure, the input voltage E, and the fixed resistance R. Is the principle obtained by. Since the potential e _Z is the sum of the measured values and the input voltage E and the fixed resistance R are constant values, the amount of change in the resistance value due to the contact pressure ΔR _CP is used as the shear stress and the ambient temperature based on the equation 12 or 13. It has the effect that it can be obtained by removing it. When the change in the electric resistance value due to the ambient temperature is small and can be ignored, the potential e _Z may be obtained by the sum of the measured potential e _1x and the measured potential e _2x _{, ignoring the measured potential e 3 on the dummy gauge side.} ..

FIG. 6 shows two tactile sensors 20 (

tactile sensors

20 and 20Y) described above, and a three-axis tactile sensor 40 arranged along each axis on the XY plane. In FIG. 6, the parts having the same reference numerals as those in FIG. 4 indicate the same elements, and thus the description thereof will be omitted. Each element on the tactile sensor 20Y side is indicated by adding Y to each corresponding element on the tactile sensor 20 side. As shown in FIG. 6, in the 3-axis tactile sensor 40, the tactile sensor 20 is arranged along the X-axis direction, and the tactile sensor 20Y is arranged along the Y-axis direction. The electrical resistance value _{R Y1} between the lower electrode 12aY and 12bY tactile sensor element 10Y constituting the tactile sensor 20Y, the electric resistance value between the lower electrode 12a'Y and 12b'Y tactile sensor element 10Y ' It was set to _RY2 . When shear stress is applied to the tactile sensor 20Y in the horizontal direction (in this case, the Y-axis direction), the electricity of the pair of tactile sensor elements 10Y and 10Y'is the same as in the case of the tactile sensor 20 described in the second embodiment. by subtracting the change in the change in resistance R _Y1 and R _Y2, it is possible to detect the Y-axis direction of the shear stress applied to the tactile sensor 20Y. When a contact pressure is applied to the tactile sensor 20Y in the vertical direction (Z-axis direction), the stress-sensitive layers 14Y and 14Y'are compressed and the electrical resistance R is as in the case of the tactile sensor 20 described in the second embodiment. The values of _Y1 and _{RY2 decrease.} Therefore, the contact pressure applied to the tactile sensor 20Y can be measured based on the relationship between the change in the electric resistance value and the contact pressure. As described above, since the 3-axis tactile sensor 40 includes not only the measurement of the shear stress in the XY-axis direction but also the measurement of the contact pressure in the Z-axis direction, the 3-axis tactile sensor 40 is used. The portion M surrounded by the alternate long and short dash line shown in FIG. 6 is the stress measurement region, which is about 3.6 × 3.6 mm ² . However, the size of the stress measurement region M is not limited to this. From the above, when contact pressure is applied to the tactile sensor 20Y in the vertical direction and / or when shear stress is applied in the horizontal direction, each tactile sensor element 10Y is the same as in the case of the tactile sensor 20 described in the second embodiment. based on the change in the value of electrical resistance _R _{Y1, R Y2} of 10Y ', the contact pressure and / or shear stress it can be detected.

The shear stress and contact pressure detection principles described in the second embodiment can be similarly applied to the three-axis tactile sensor 40 of the third embodiment. FIG. 7 is a circuit diagram in which the 3-axis tactile sensor 40 shown in FIG. 6 is composed of a bridge circuit 50. In FIG. 7, the parts having the same reference numerals as those in FIG. 5 indicate the same elements, and thus the description thereof will be omitted. As shown in FIG. 7, in the 3-axis tactile sensor 40, the x-axis bridge circuit formed by the tactile sensor 20 arranged on the x-axis and the y-axis bridge circuit formed by the tactile sensor 20Y arranged on the y-axis are arranged in parallel. It constitutes a combined xy-axis bridge circuit. An input voltage E is applied between the branch point r connecting the electrical resistances _RX1 , _RX2 , _RY1 , _RY2, and _{RDG and the ground.} An input voltage E is commonly applied to _{the branch points of the resistors R X1} and _RX2 of the x-axis bridge circuit and the branch points of the resistors _RY1 and _{RY2 of the y-axis bridge circuit.} e _1Y is the measured potential between the branch point c and the ground, and e _2Y is the measured potential between the branch point d and the ground.

When the shear stress when the direction perpendicular to the contact pressure is applied and horizontally tactile sensor 20Y is applied, the change e _Y voltage by shear stress is given similarly to Equation 6. Equation 14 below summarizes _{the changes in voltage e X} and e _Y due to shear stress in the 3-axis tactile sensor 40. However, in order to distinguish the X and Y directions, the amount of change in resistance value due to shear stress ΔR _SS was set to ΔR _SSX and ΔR _SSY .

When the shear stress when the direction perpendicular to the contact pressure is applied and horizontally tactile sensor 20Y is applied, the change e _Z voltage by contact pressure is given as for formula 12. Equation 15 below summarizes the changes in voltage due to contact pressure in the 3-axis tactile sensor 40. However, to distinguish X, the Y-direction, a change in the voltage due to contact pressure at the

tactile sensor

20,20Y and _{e ZX} and _{e ZY,} and the change amount [Delta] R _CP in resistance due to the contact pressure [Delta] R _CPX, and [Delta] R _CPY.

The average (e _XY ) of e _ZX and e _ZY of Equation 15 is as shown in Equation 16.

Here, _{when it can be regarded as ΔR CPX} = ΔR _CPY = ΔR _CP , the equation 16 becomes the equation 17.

When the change in the electric resistance value due to the ambient temperature is small and can be ignored (e _1x , e _2x , e _1Y , e _2x >> e ₃ ), the equation 18 may be used.

FIG. 8 is a photograph of the 3-axis tactile sensor 40, and the stress measurement region M described above is shown.

From the above, according to the third embodiment of the present invention, two tactile sensors 20 (

tactile sensors

20 and 20Y) of the second embodiment are manufactured, and a three-axis tactile sensor 40 arranged along each axis on the XY plane is produced. did. When a contact pressure is applied to the tactile sensor 20Y in the vertical direction and / or a shear stress is applied in the horizontal direction, the tactile sensor elements 10Y and 10Y'are the same as in the case of the tactile sensor 20 described in the second embodiment. The contact pressure and / or shear stress can be detected based on the change in the values of the electric resistances _RY1 and _RY2. The shear stress and contact pressure detection principles described in the second embodiment can be similarly applied to the three-axis tactile sensor 40 of the third embodiment. The 3-axis tactile sensor 40 is an xy-axis bridge circuit in which an x-axis bridge circuit composed of the tactile sensor 20 arranged on the x-axis and a y-axis bridge circuit composed of the tactile sensor 20Y arranged on the y-axis are combined in parallel. It is configured. When the shear stress when the direction perpendicular to the contact pressure is applied and horizontally tactile sensor 20Y is applied, the change e _Y voltage by shear stress is given similarly to Equation 6 in Example 2. _{Therefore, the voltage changes e X} and e _Y due to the shear stress in the 3-axis tactile sensor 40 can be collectively expressed by the equation 14. When the shear stress when the direction perpendicular to the contact pressure is applied and horizontally tactile sensor 20Y is applied, the change e _Z voltage by contact pressure is given as for formula 12 in Example 2. Therefore, the change in voltage due to the contact pressure in the 3-axis tactile sensor 40 can be collectively expressed by Equation 15.

Since the manufacturing of each tactile sensor element 10 and the like constituting the 3-axis tactile sensor 40 uses a stacking process, it is possible to reduce the thickness of the tactile sensor by using the 3-axis tactile sensor 40, and there are individual differences in manufacturing. It has the effect of making it possible to manufacture products with less variation. The lower electrode 12a and the like of each tactile sensor element 10 and the like constituting the three-axis tactile sensor 40 and the stress-sensitive layer 14 and the like, and the stress-sensitive layer 14 and the like and the upper electrode 16 and the like have a structure in which they are laminated in close contact with each other. There is. Therefore, the 3-axis tactile sensor 40 has the effect of improving measurement stability and enabling highly sensitive measurement even under low stress. In other words, in the 3-axis tactile sensor 40 of the present invention, the stress-sensitive layer 14 or the like responsible for sensing is brought into close contact with the upper electrode 16 or the like and the lower electrode 12a or the like by stacking, and the above-mentioned dedicated measurement principle is devised. As a result, the tactile sensor is made thinner because the thickness of the detection layer is thin while the stress detection layer has room to be sufficiently deformed in the direction of stress, and the measurement stability is improved even under low stress for highly sensitive measurement. There is an effect that the 3-axis tactile sensor 40 capable of providing the three-axis tactile sensor 40 can be provided.

Calibration device.
FIG. 9A schematically shows the calibration device 60 of the 3-axis tactile sensor 40. 9 (B) and 9 (C) are photographs of the calibration device 60. As shown in FIG. 9A, the 3-axis tactile sensor 40 is placed on the base 61, and the acrylic plate 63 is placed ^{on the 3-axis tactile sensor 40 via a punch (rubber, 7 × 7 mm 2) 62.} A weight 64 for applying contact pressure is placed on the acrylic plate 63. A piezo actuator (MZ-1300ZL, manufactured by Mestec Co., Ltd., maximum displacement 1.3 mm) 72 that generates a horizontal displacement for shear stress is used, and a load cell (USM-5N, manufactured by Unipulse Corporation, USM-5N) 71 is used as a piezo actuator 72. It was set at the tip, and the load cell 71 and the acrylic plate 63 were connected by a wire 70. Although not shown in FIG. 9, a piezo driver (manufactured by Mestec Co., Ltd., M-2691) is connected to the piezo actuator 72, and a DC constant voltage source (manufactured by Matsusada Precision Co., Ltd., P4K-80L) is connected to the piezo actuator 72. ing. The voltage applied to the piezo actuator 72 was a step drive (rectangular wave) type of 0 to 5 V. With the above configuration, the shear stress on the 3-axis tactile sensor 40 is applied by pulling the punch 62 in the horizontal direction by the wire 70 (via the acrylic plate 63) with the piezo actuator 72, and the contact pressure applies the weight 64 to the acrylic plate. Applied by placing at 63. FIG. 9B shows a state in which the 3-axis tactile sensor 40 is mounted on the base 61. The calibrator 60 is provided with rails 65 (two slots), which can adjust the position of the piezo actuator 72 and the position of the base 61. FIG. 9C shows a state in which the punch 62, the acrylic plate 63, and the weight 64 are further placed on the 3-axis tactile sensor 40 in the state of FIG. 9B.

Calibration test.
FIG. 10 shows a material testing machine used for the contact pressure calibration test. As the material testing machine, Autograph (registered trademark) AGS-J 5kN manufactured by Shimadzu Corporation (registered trademark) was used. FIG. 11 shows a partially enlarged view of the material testing machine shown in FIG. As shown in FIG. 11, a sponge rubber punch 80 (7 × 7 mm ² ) was placed on the 3-axis tactile sensor 40. The input voltage to the bridge circuit 50 was E = 5V, and the contact pressure was changed from 0 to 5 kPa. Under these conditions, the above-mentioned potentials e _1x , e _2x , e _1Y , e _2Y , e _{3 and the} like were actually measured. The results will be described later (Fig. 12). The calibration device 60 shown in FIG. 9 was used for the shear stress calibration test. The input voltage to the bridge circuit 50 was set to E = 5V, and the shear stress was changed from -8 to +8 kPa. At the same time, a contact pressure of 4 kPa was applied through the punch 62 by the weight 64. The results will be described later (FIGS. 13 to 14).

Experimental result.
FIG. 12 graphically shows the result of the contact pressure calibration experiment. In FIG. 12, the horizontal axis is the contact pressure (kPa), and the vertical axis is the output voltage (V) (for example, the above-mentioned potentials e _1x , e _2x , e _XY, etc.). As shown in FIG. 12, the output voltage increases with increasing contact pressure. Therefore, it was found that equations 15 and 16 and the like were correct. Note that ΔR _CP is basically a negative value.

FIG. 13 is a graph showing the results of a calibration experiment when shear stress is applied under a contact pressure of 4 kPa (weight 64). 13 (A) and 13 (B) are measurement results for the X-axis and the Y-axis, respectively. In FIGS. 13A and 13B, the horizontal axis is the shear stress (kPa) and the vertical axis is the output voltage (V) (for example, the potentials e _1x , e _1Y , e _X , e _Y, etc. described above). In FIG. 13 (A), the result of the first experiment is shown by a light circle (orange in the original drawing), the result of the second experiment is shown by a dark circle (red in the original drawing), and in FIG. 13 (B), the result of the first experiment is shown. The experimental results are indicated by dark 〇 (green), and the results of the second experiment are indicated by light 〇 (light blue). As shown in FIGS. 13A and 13B, the initial voltage of the 3-axis tactile sensor 40 is shifted to 0V. In both the X-axis and the Y-axis, the output voltage increases with the increase in shear stress, and the change (that is, slope) of the output voltage with respect to the increase in shear stress is almost the same for both the first and second times. ing. Therefore, the shear stress can be determined from the output voltage by using this slope. Therefore, it was found that Equation 14 was correct.

FIG. 14 is a graph showing the results of a calibration experiment when shear stress is applied while the contact pressure (weight 64) is changed to 2 kPa and 4 kPa. In FIG. 14, the horizontal axis is the shear stress (kPa), and the vertical axis is the output voltage (V) (for example, the above-mentioned potentials e _1x , e _1Y , e _X , e _Y, etc.). In FIG. 14, the experimental result of the contact pressure of 2 kPa is shown in a dark color (blue in the original drawing), and the experimental result of 4 kPa is shown in a light color (orange in the original figure). As shown in FIG. 14, since a straight line having the same slope and intercept was obtained regardless of the contact pressure (weight 64), it was shown that the output voltage changes only by the shear stress. Therefore, it was shown that even when the contact pressure and the shear stress are applied in combination, only the shear stress can be measured independently. This proved the correctness of the measurement principle of the present invention described above. In addition, as shown in FIGS. 12-14, it was also shown that a stable output voltage can be obtained even under low stress.

As an example of utilization of the present invention, a stable output voltage can be obtained even under low stress, so that it can be applied as a biological contact interface. For example, it can be applied to the tip of a robot hand that comes into contact with a person, or as an input interface for an electronic device.

10, 10', 10 _DG , 10Y, 10Y' Tactile sensor elements, 12, 12a, 12b, 12a', 12b', 12aY, 12bY, 12a'Y, 12b'Y, 12a _DG , 12b _DG lower electrode, 12r, 12ra, 12rb, 12ra', 12rb'One end side of the lower electrode, 14, 14', 14 _DG , 14Y, 14Y'Stress sensitive layer, 16, 16', 16 _DG , 16Y, 16Y'Upper electrode, 20, 20Y Tactile Sensors, 30, 50 bridge circuits, 60 calibrators, 61 bases, 62 punches, 63 acrylic plates, 64 weights, 70 wires, 71 load cells, 72 piezo actuators.

Claims

A tactile sensor having a structure in which a pair of lower electrodes, a stress-sensitive layer formed straddling each one end side of the pair of lower electrodes, and an upper electrode formed on the stress-sensitive layer are laminated. The element has a region on each one end side of the pair of lower electrodes that vertically overlaps the lower electrode and the upper electrode on a plane.
When a contact pressure is applied to the tactile sensor element in the vertical direction, the stress-sensitive layer is compressed and the electrical resistance between both electrodes (the upper electrode and the lower electrode) is reduced.
When shear stress is applied to the tactile sensor element in the horizontal direction, the electrical resistance between the two electrodes increases in the direction in which the overlapping region decreases, and between the two electrodes in the direction in which the overlapping region increases. A tactile sensor element characterized by reduced electrical resistance.
A tactile sensor in which two tactile sensor elements according to claim 1 are arranged on one axis of a plane with one end side of each of the pair of lower electrodes facing each other, and a contact pressure is applied to the tactile sensor in a vertical direction. A tactile sensor characterized in that the contact pressure and / or the shear stress is detected based on the change in the electrical resistance of each tactile sensor element when the shear stress is applied and / or in the horizontal direction.
In the tactile sensor according to claim 2, the tactile sensor includes the electric resistance of the first tactile sensor element (first sensor resistance), the electric resistance of the second tactile sensor element (second sensor resistance), and the contact pressure. And a bridge circuit based on the first sensor resistance and the second sensor resistance (fixed resistance) when there is no shear stress load, and each resistance value is the resistance value when the bridge circuit is in equilibrium state, and the opposite side is the first. One sensor resistance and fixed resistance are arranged, the second sensor resistance and fixed resistance are arranged on the other opposite side, and an input voltage is applied to the branch point between the first sensor resistance and the second sensor resistance.
The amount of change in the resistance value of the first sensor resistance (first sensor resistance value) and the resistance value of the second sensor resistance (second sensor resistance value) depends on the contact pressure applied to the tactile sensor, the shear stress, and the ambient temperature. Given, the amount of change in the first sensor resistance value due to shear stress and the amount of change in the second sensor resistance value are equal in absolute value (referred to as "the amount of change in sensor resistance value due to shear stress") and are in contact with each other. A tactile sensor characterized in that the amount of change in the resistance value of the first sensor due to pressure and the amount of change in the resistance value of the second sensor (referred to as "amount of change in sensor resistance value due to contact pressure") are equal.
In the tactile sensor according to claim 3, when contact pressure and shear stress are applied to the tactile sensor, the measured potential for the ground contact of the branch point in one opposite side and the actual measurement for the ground contact of the branch point in the other opposite side. Based on the principle that the potential difference from the potential is obtained by the amount of change in the sensor resistance value due to the shear stress, the input voltage, and the resistance value of the fixed resistance, the amount of change in the sensor resistance value due to the shear stress is contacted. A tactile sensor characterized by removing pressure and ambient temperature.
In the tactile sensor according to claim 3 or 4, when contact pressure and shear stress are applied to the tactile sensor, the measured potential with respect to the grounding of the branch point in the one opposite side and the grounding of the branch point in the other opposite side. Based on the principle that the potential of the sum of the measured potential and the measured potential is obtained by the amount of change in the sensor resistance value due to the contact pressure, the input voltage, and the resistance value of the fixed resistance, the amount of change in the sensor resistance value due to the contact pressure. A tactile sensor characterized by removing shear stress and ambient temperature.
A three-axis tactile sensor in which two tactile sensors according to claim 2 are arranged along two axes on a plane, when a contact pressure is applied to the three-axis tactile sensor in the vertical direction and / or in the horizontal direction. A 3-axis tactile sensor characterized in that contact pressure and / or shear stress is detected based on a change in the electric resistance value of each tactile sensor element when a shear stress is applied to the sensor.
A three-axis tactile sensor in which the two tactile sensors according to any one of claims 3 to 5 are arranged along two axes (xy axes) on a plane.
The 3-axis tactile sensor constitutes an xy-axis bridge circuit in which an x-axis bridge circuit composed of a tactile sensor arranged on the x-axis and a y-axis bridge circuit composed of a tactile sensor arranged on the y-axis are combined in parallel. , A 3-axis tactile sensor characterized in that an input voltage is commonly applied to a branch point of each sensor resistance of an x-axis bridge circuit and a branch point of each sensor resistance of a y-axis bridge circuit.
The method for manufacturing a tactile sensor element according to claim 1.
A lower electrode forming step of printing a pair of lower electrodes with silver ink on a predetermined base film and forming the lower electrodes.
A stress-sensitive layer forming step of applying a predetermined conductive polymer over a pair of lower electrodes formed in the lower electrode forming step to form a stress-sensitive layer.
A method for manufacturing a tactile sensor element, which comprises a step of forming an upper electrode by printing a metal ink on the stress-sensitive layer formed in the step of forming the stress-sensitive layer.