Tactile Sensor

A tactile sensor has an electrostatic capacitance-type sensor portion having a layered structure in which a first electrode layer, an elastic layer, and a second electrode layer are layered. The first electrode layer has plural first electrodes, and the second electrode layer is configured by one or plural second electrodes in a single layer. Two or more of the plural first electrodes are partially-overlapping electrodes that partially overlap with the second electrode as viewed in a normal direction of a contacting surface of the sensor portion. A number of one or plural openings formed in one of the second electrodes, or a number of one or plural island portions formed by one or plural second electrodes, is less than a number of the plural first electrodes.

TECHNICAL FIELD

The technique disclosed in the present application relates to a tactile sensor.

BACKGROUND ART

The following techniques, for example, are known as tactile sensors that can sense the pressure distribution and shearing forces of a contacting surface that contacts an object.

Namely, the tactile sensor disclosed in Patent Document 1 has a supporting substrate, a first insulating body, a second insulating body, plural electrodes, plural first strip-shaped electrodes, and plural second strip-shaped electrodes. The supporting substrate, the second insulating body and the first insulating body are layered so as to be lined-up in that order from the side opposite the side at which pressure is inputted to the tactile sensor.

The plural electrodes are provided so as to be spread all over the entirety between the second insulating body and the supporting substrate. The plural first strip-shaped electrodes are provided so as to extend in a first direction at the side of the first insulating body, which side is at the opposite side of the second insulating body. Due to the plural first strip-shaped electrodes extending between, of the plural electrodes, the electrodes that are adjacent to one another in a direction intersecting the first direction, the first strip-shaped electrodes overlap only portions of these adjacent electrodes respectively as viewed in plan view.

The plural second strip-shaped electrodes are provided between the first insulating body and the second insulating body, so as to extend in a second direction that intersects the first direction. Due to the plural second strip-shaped electrodes extending between, of the plural electrodes, the electrodes that are adjacent to one another in a direction intersecting the second direction, the second strip-shaped electrodes overlap only portions of these adjacent electrodes respectively as viewed in plan view.

The tactile sensor is connected to an electrostatic capacitance measuring circuit. The electrostatic capacitance measuring circuit can detect the electrostatic capacitances that are generated between the electrodes and the first strip-shaped electrodes that overlap those electrodes as viewed in plan view. Further, the electrostatic capacitance measuring circuit can detect the electrostatic capacitances that are generated between the electrodes and the second strip-shaped electrodes that overlap those electrodes as viewed in plan view.

The tactile sensor disclosed in Patent Document 2 has a first substrate, a second substrate, and a dielectric. The first substrate has plural first electrodes. The second substrate has plural second electrodes that correspond respectively to the plural first electrodes. The dielectric is provided between the first substrate and the second substrate.

A second electrode that corresponds to any one first electrode among the plural first electrodes is disposed so as to be offset in one direction within the second substrate with respect to the any one first electrode. Another second electrode, which corresponds to another first electrode that is adjacent to the any one first electrode, is disposed so as to be offset in another direction within the second substrate with respect to the another first electrode.

The plural first electrodes correspond one-to-one to the plural second electrodes. The plural first electrodes are disposed so as to be apart from one another, and the plural second electrodes are disposed so as to be apart from one another.

PRIOR ART DOCUMENTS

Patent Documents

SUMMARY OF INVENTION

Technical Problem

In the tactile sensor disclosed in Patent Document 1, facing electrodes that face the plural electrodes are two-layer structures of the plural first strip-shaped electrodes and the plural second strip-shaped electrodes. Therefore, the structure of the tactile sensor is complex, and the processes of manufacturing the tactile sensor also are complex.

In the tactile sensor disclosed in Patent Document 2, the plural first electrodes correspond one-to-one to the plural second electrodes. Further, in order to detect shearing forces, the plural first electrodes are disposed so as to be apart from one another, and the plural second electrodes as well are disposed so as to be apart from one another. Accordingly, the intervals between the plural first electrodes are large, and the intervals between the plural second electrodes are large. Therefore, the numbers of the plural first electrodes and the plural second electrodes cannot be increased, and the resolution of the pressure distribution decreases.

Accordingly, there is room for improvement in order to be able to detect shearing forces and ensure the resolution of the pressure distribution, even by a simple structure and simple manufacturing processes.

An object of one aspect of the technique disclosed in the present application is to obtain a tactile sensor that can detect shearing forces and ensure the resolution of the pressure distribution, even by a simple structure and simple manufacturing processes.

Solution to Problem

In order to achieve the above-described object, in accordance with one aspect of the technique disclosed in the present application, there is provided a tactile sensor comprising an electrostatic capacitance-type sensor portion having a contacting surface that contacts an object, and having a layered structure in which an elastic layer, and a first electrode layer and a second electrode layer positioned at respective sides of the elastic layer with the elastic layer sandwiched therebetween, are layered in a normal direction of the contacting surface, wherein the first electrode layer has a plurality of first electrodes, the second electrode layer is configured by one or a plurality of second electrodes in a single layer, two or more of the plurality of first electrodes are partially-overlapping electrodes that partially overlap with the second electrode as viewed in the normal direction, and a number of one or a plurality of openings formed in one of the second electrodes, or a number of one or a plurality of island portions formed by one or a plurality of the second electrodes, is less than a number of the plurality of first electrodes.

Advantageous Effects of Invention

In accordance with the tactile sensor relating to one aspect of the technique disclosed in the present application, shearing forces can be detected, and the resolution of the pressure distribution can be ensured, even by a simple structure and simple manufacturing processes.

DESCRIPTION OF EMBODIMENTS

An embodiment of the technique disclosed in the present application is described in detail hereinafter with reference to the appended drawings.

Example of Robot System100

First, an overview of an example of a robot system100is described.

FIG.1is a perspective view illustrating an example of a robot system100. The robot system100has a robot102and a controller104. The robot102is an articulated robot for example, and has a robot arm106and a robot hand108. The robot arm106has plural joint portions110. The robot hand108is provided at the distal end portion of the robot arm106. The robot hand108is connected to the distal end portion of the robot arm106via a wrist joint portion112.

A pair of grasping portions114are provided at the robot hand108. The pair of grasping portions114are disposed so as to face one another. The pair of grasping portions114approach and move away from one another in the direction in which they face one another, due to the driving of an unillustrated driving section. When the pair of grasping portions114move in directions of approaching one another in a state in which a workpiece W is disposed therebetween, the workpiece W is grasped by the pair of grasping portions114.

The controller104controls the robot102, and is electrically connected to the robot102. InFIG.1, as an example, the controller104is connected to the robot102by a wire, but the controller104may be wirelessly connected to the robot102.

Example of Tactile Sensing System1

An overview of an example of a tactile sensing system1is described next.

The tactile sensing system1is installed in the robot system100. The tactile sensing system1has a pair of tactile sensors10and an output section12. The pair of tactile sensors10are provided respectively at mutually facing surfaces114A of the pair of grasping portions114. The pair of tactile sensors10are provided at positions that contact the workpiece W in the state in which the workpiece W is grasped by the pair of grasping portions114, i.e., as an example, are provided at the portions, which face one another, of the distal end portions of the pair of grasping portions114.

The output section12is electrically connected to the pair of tactile sensors10. The output section12may be connected to the pair of tactile sensors10by wires, or may be wirelessly connected to the pair of tactile sensors10. As described in detail later, the output section12has the functions of carrying out various types of processings on the basis of data outputted from the pair of tactile sensors10, and outputting data that is based on the results of these processings to the controller104. The output section12is provided at the wrist joint portion112as an example.

FIG.2is a perspective view illustrating an example of the pair of tactile sensors10ofFIG.1. As an example, the pair of tactile sensors10have plane symmetry in the direction of facing one another. The X-axis direction corresponds to a first direction that is orthogonal to the direction in which the pair of tactile sensors10face one another. The Y-axis direction corresponds to a second direction that is orthogonal to the direction in which the pair of tactile sensors10face one another. The Z-axis direction corresponds to the direction in which the pair of tactile sensors10face one another. The X-axis direction is orthogonal to the Y-axis direction. As an example, the X-axis direction corresponds to the length direction of the tactile sensors10, and the Y-axis direction corresponds to the width direction of the tactile sensors10.

The tactile sensor10has a supporting plate14, a substrate16, and a sensor portion18. The supporting plate14is configured by a body that is separate from the above-described grasping portion114(seeFIG.1), and is fixed to the grasping portion114. The supporting plate14may be structured integrally with the grasping portion114. The substrate16is fixed to the supporting plate14, and the sensor portion18is provided on the substrate16. Details of the sensor portion18are described later.

First through fourth embodiments of the tactile sensing system1are described next.

First Embodiment

A first embodiment is described first.

FIG.3is a vertical sectional view of the tactile sensor10relating to the first embodiment. The tactile sensor10relating to the first embodiment has the sensor portion18and the substrate16.

The sensor portion18is an electrostatic capacitance-type sensor. More specifically, this sensor portion18is a self-capacitance-type sensor, and has a layered structure in which plural layers are layered. Namely, the sensor portion18has, as the plural layers, an insulating layer20, an elastic layer22, a first electrode layer24and a second electrode layer26. The first electrode layer24and the second electrode layer26are positioned at the respective sides of the elastic layer22so as to sandwich the elastic layer22therebetween.

The insulating layer20is positioned at the side of the second electrode layer26, which side is opposite the elastic layer22. The insulating layer20forms the surface layer portion of the sensor portion18. The obverse of the insulating layer20is formed as a contacting surface28that contacts the workpiece W (seeFIG.1). Note that the insulating layer20may be omitted. In a case in which the insulating layer20is omitted, the obverse of the second electrode layer26, or of a surface layer formed on the second electrode layer26, is the contacting surface28.

The elastic layer22is a dielectric. The elastic layer22is flexible and elastic. The elastic layer22is formed by a gel for example. The insulating layer20, the elastic layer22, the first electrode layer24and the second electrode layer26are layered in the Z-axis direction. The Z-axis direction corresponds to the normal direction of the contacting surface28. The insulating layer20, the elastic layer22, the first electrode layer24and the second electrode layer26are adhered to one another by an adhesive or the like for example. In order to increase the adhesive strength of the sensor portion18overall, it is preferable that the insulating layer20be a size that covers the entire surface of the second electrode layer26.

The first electrode layer24has plural first electrodes34. The plural first electrodes34are formed on a first surface16A that is at the sensor portion18side of the substrate16. Plural electrostatic capacitance detecting ICs (Integrated Circuits)44are packaged on a second surface16B, which is at the side opposite the sensor portion18, of the substrate16. The plural first electrodes34and the plural electrostatic capacitance detecting ICs44are connected by through-hole vias46that extend in the plate thickness direction of the substrate16.

FIG.4is a plan view of the substrate16ofFIG.3. The plural first electrodes34that are formed on the first surface16A of the substrate16are arrayed in the form of a matrix along the X-Y plane. Namely, the plural first electrodes34are arrayed with the X-axis direction being the length direction and the Y-axis direction being the width direction. The X-Y plane is the plane that is parallel to the aforementioned contacting surface28(seeFIG.2).

The plural first electrodes34are independent of one another. The plural first electrodes34have the same shape. As an example, the plural first electrodes34are formed in square shapes as viewed in plan view. Viewing in plan view corresponds to viewing in the Z-axis direction. As an example, the plural first electrodes34are arrayed such that there are six thereof in the X-axis direction and six thereof in the Y-axis direction. Namely, the number of the plural first electrodes34is 36. These plural first electrodes34are arrayed at uniform intervals in the X-axis direction and the Y-axis direction, respectively.

FIG.5is a plan view of the second electrode layer26ofFIG.3. The second electrode layer26is configured by plural second electrodes36in a single layer. The plural second electrodes36are formed of a conductive rubber for example. The plural second electrodes36are respectively formed in the shapes of flat plates. The plural second electrodes36may be connected to the ground of the substrate16, or may be floating with respect to ground.

The plural second electrodes36form plural islands that are independent of one another. The plural second electrodes36are arrayed in the form of a matrix along the X-Y plane. Namely, the plural second electrodes36are arrayed with the X-axis direction being the length direction and the Y-axis direction being the width direction.

The plural second electrodes36are the same shape. As an example, the plural second electrodes36are respectively formed in square shapes as viewed in plan view. The number of the plural second electrodes36is less than the number of the above-described, plural first electrodes34(seeFIG.4). As an example, the plural second electrodes36are arrayed such that there are three thereof in the X-axis direction and three thereof in the Y-axis direction. Namely, the number of the plural second electrodes36is nine. These plural second electrodes36are arrayed at uniform intervals in the X-axis direction and the Y-axis direction, respectively.

FIG.6is a plan view illustrating a state in which the plural second electrodes36and the elastic layer22and the substrate16ofFIG.3are superposed. The plural second electrodes36are disposed so as to be superposed with all of the plural first electrodes34as viewed in plan view. As viewed in plan view, the plural second electrodes36are respectively formed so as to partially overlap with the respective, four first electrodes34that are adjacent in the X-axis direction and the Y-axis direction, among the plural first electrodes34. As viewed in plan view, the respective second electrodes36are positioned at the central portions of the four first electrodes34, and partially overlap with these four first electrodes34.

In this way, in the first embodiment, all of the plural first electrodes34partially overlap with the plural second electrodes36. In this first embodiment, all of the plural first electrodes34correspond to an example of the “plurality of partially-overlapping electrodes that partially overlap with the plurality of second electrodes”, and the plural signals that are outputted from the plural first electrodes34correspond to an example of the “plurality of partially-overlapping electrode signals”.

In the first embodiment, all of the plural first electrodes34correspond to an example of the “plurality of partially-overlapping electrodes that partially overlap with the second electrode”, and the plural signals that are outputted from the plural first electrodes34correspond to an example of the “plurality of partially-overlapping electrode signals”.

Electrostatic capacitance C[F] between the first electrode34and the second electrode36is determined by the following formula.

ε is the dielectric constant [Fm-1] of the elastic layer22, A is the surface area [m2] over which the first electrode34and the second electrode36overlap one another as viewed in plan view, and d is the distance [m] between the first electrode34and the second electrode36along the Z-axis direction.

At this sensor portion18, when pressure is applied to the contacting surface28, and the distance d between each first electrode34and the second electrode36changes, the electrostatic capacitance C changes in accordance with this change in the distance d. Further, at the sensor portion18, when shearing force is applied to the contacting surface28, and the surface area A over which each first electrode34and the second electrode36overlap one another changes, the electrostatic capacitance C changes in accordance with this change in the surface area A.

Note that, although described in detail hereinafter, the pressure that is applied to the contacting surface28corresponds to the force that is applied to the contacting surface28along the Z-axis direction. Further, the shearing force that is applied to the contacting surface28corresponds to the force that is applied to the contacting surface28along a direction orthogonal to the Z-axis direction. Directions orthogonal to the Z-axis direction include the X-axis direction, the Y-axis direction, and directions that combine the X-axis direction and the Y-axis direction.

The plural first electrodes34are driven by the electrostatic capacitance detecting ICs44(seeFIG.3andFIG.7) that are described later, and respectively output signals corresponding to the electrostatic capacitances C between the first electrodes34and the second electrodes36. Namely, the sensor portion18outputs plural signals that respectively correspond to the plural first electrodes34. These plural signals are analog signals.

FIG.7is a bottom view of the substrate16ofFIG.3. The plural electrostatic capacitance detecting ICs44are arrayed in the form of a matrix along the X-Y plane. Namely, the plural electrostatic capacitance detecting ICs44are arrayed with the X-axis direction being the length direction and the Y-axis direction being the width direction. The plural electrostatic capacitance detecting ICs44have the same structure. As an example, the plural electrostatic capacitance detecting ICs44are arrayed such that there are three thereof in the X-axis direction and three thereof in the Y-axis direction. Namely, the number of the plural electrostatic capacitance detecting ICs44is nine.

To each of the electrostatic capacitance detecting ICs44is connected the four first electrodes34that overlap that electrostatic capacitance detecting IC as viewed in plan view. Each of the electrostatic capacitance detecting ICs44is driven by the four first electrodes34, and is a structure that can output data corresponding to the signals outputted from those four first electrodes34.

(Method of Manufacturing Tactile Sensor10)

FIG.8is a drawing explaining an example of a method of manufacturing the tactile sensor10ofFIG.3. The tactile sensor10is manufactured by the following procedures for example. Namely, the plural electrostatic capacitance detecting ICs44are packaged on the second surface16B of the substrate16at which the plural first electrodes34are formed on the first surface16A by a pattern. The plural through-hole vias46are formed in the substrate16, and the plural electrostatic capacitance detecting ICs44are connected to the plural first electrodes34via the plural through-hole vias46.

Next, the elastic layer22is layered on the first electrode layer24that has the plural first electrodes34. Further, the second electrode layer26that is configured by the plural second electrodes36(seeFIG.5) is layered on the elastic layer22, and moreover, the insulating layer20is layered on this second electrode layer26. The insulating layer20, the elastic layer22, the first electrode layer24and the second electrode layer26are adhered to one another by an adhesive or the like for example. The tactile sensor10is manufactured by the above-described procedures.

Note that, as illustrated inFIG.5, punching processing, cutting processing, cast molding, metal press molding, and the like are examples of processing methods that form plural openings38in the second electrodes36.

FIG.9is a plan view explaining an example of displacement Δx and displacement Δy at the tactile sensor10ofFIG.3. Note that, inFIG.9, electrostatic capacitances C00~ C55between the respective, plural first electrodes34and the second electrodes36are illustrated so as to correspond to the plural first electrodes34, respectively.

FIG.10is a drawing explaining examples of displacement Δx and displacement Δz at the tactile sensor10ofFIG.3. InFIG.10, (A) illustrates a case in which there is no normal load Fz′, (B) illustrates a case in which there is the normal load Fz′, (C) illustrates a case in which there is shearing force Fx, and (D) illustrates a case in which there is the normal load Fz′ and there is the shearing force Fx, respectively.

FIG.11is a drawing explaining examples of displacement Δy and displacement Δz at the tactile sensor10ofFIG.3. InFIG.11, (A) illustrates a case in which there is no normal load Fz′, (B) illustrates a case in which there is the normal load Fz′, (C) illustrates a case in which there is shearing force Fy, and (D) illustrates a case in which there is the normal load Fz′ and there is the shearing force Fy, respectively.

As illustrated inFIG.9andFIG.10, displacement Δx corresponds to the distance that the second electrode36moves along the X-axis direction accompanying application of the shearing force Fx. Similarly, as illustrated inFIG.9andFIG.11, displacement Δy corresponds to the distance that the second electrode36moves along the Y-axis direction accompanying application of the shearing force Fy.

As illustrated inFIG.10andFIG.11, distance Z0corresponds to the distance along the Z-axis direction between the first electrode34and the second electrode36at the time when the normal load Fz′ is not applied. Displacement Δz corresponds to the distance that the second electrode36moves along the Z-axis direction toward the first electrode34side accompanying application of the normal load Fz′.

Examples of calculating the displacements Δx, Δy, Δz are described hereinafter by using the first electrodes34, which are adjacent to one another and partially overlap with one of the second electrodes36, as an example.

As illustrated inFIG.10(A)andFIG.11(A), when the normal load Fz′ is not applied, Δx, Δy, Δz = 0, and Formula 1 is established for the first electrodes34that are adjacent to one another and partially overlap with the second electrode36.

C00_0, C01_0are the electrostatic capacitances between the adjacent first electrodes34and the second electrode36when normal load Fz′ is not applied, and K1, K2 are constants.

A formula similar to Formula 1 is established also for the electrostatic capacitances between the other adjacent first electrodes34and the second electrode36.

As illustrated inFIG.10(B)andFIG.11(B), when only the normal load Fz′ is applied, Δx, Δy = 0, and Δz ≠ 0, and Formula 2 is established for the first electrodes34that are adjacent to one another and partially overlap with the second electrode36.

C00_z, C01_zare the electrostatic capacitances between the adjacent first electrodes34and the second electrode36when only the normal load Fz′ is applied.

The following are determined from Formula 2.

From Formula 1, the displacement Δz of the second electrode36with respect to one first electrode34is determined as follows.

Similarly, the displacement Δz of the second electrode36with respect to the other first electrode34is determined as follows.

The displacement Δz of the second electrode36with respect to the other first electrodes34is determined in the same way as described above.

As illustrated inFIG.10(C), when only the shearing force Fx is applied, Δy, Δz = 0, and Δx ≠ 0, and Formula 3 is established for the first electrodes34that are adjacent to one another and partially overlap with the second electrode36.

C00_x, C01_xare the electrostatic capacitances between the first electrodes34that are adjacent to one another in the x direction and the second electrode36when only the shearing force Fx is applied, and Kp is a constant.

The following are determined from Formula 3.

From Formula 1, because K1 = Z0×C00_0, the displacement Δx of the second electrode36with respect to one first electrode34is determined as follows.

Similarly, the displacement Δx of the second electrode36with respect to the other first electrode34is determined as follows.

The displacement Δx of the second electrode36with respect to the other first electrodes34is determined in the same way as described above.

As shown inFIG.11(C), when only the shearing force Fy is applied, the displacement Δy of the second electrode36with respect to the first electrode34is determined by calculation that is similar to when only the shearing force Fx is applied.

As illustrated inFIG.10(D), when the normal load Fz′ and only the shearing force Fx are applied, Δy = 0, and Δx, Δz ≠ 0, and Formula 4 is established for the first electrodes34that are adjacent to one another and partially overlap with the second electrode36.

C00_zx, C01_zxare the electrostatic capacitances between the first electrodes34and the second electrode36when the normal load Fz′ and only the shearing force Fx are applied.

From Formula 4, the displacements Δz, Δx of the second electrode36with respect to the first electrode34are determined as follows.

The displacements Δz, Δx of the second electrode36with respect to the other first electrode34are determined in the same way as described above.

As illustrated inFIG.11(D), when the normal load Fz′ and only the shearing force Fy are applied, the displacements Δz, Δy of the second electrode36with respect to the first electrodes34that are adjacent to one another are determined by calculation that is similar to when the normal load Fz′ and only the shearing force Fx are applied.

(When Normal Load Fz′ and Shearing Forces Fx, Fy are Applied: Δx, Δy, Δz ≠ 0) When the normal load Fz′ and the shearing forces Fx, Fy are applied, the displacements Δx, Δy, Δz of the second electrode36with respect to the first electrode34can be determined as follows. In the range of the four first electrodes34that partially overlap with the one second electrode36, it is often the case that the values of the displacement Δz at the respective first electrodes34approximate one another, and therefore, it is assumed that the value of the displacement Δz can be used in common therefor. In this case, the magnitude of the signal (the electrostatic capacitance value) corresponding to each first electrode34is proportional to the surface area of overlapping of the first electrode34with the second electrode36. Accordingly, the ratio of electrostatic capacitance values C00, C01, C10, C11is equal to the ratio of overlapping surface areas S00, S01, S10, S11. Namely, Formula 5 is established.

Given that the square root of the overlapping surface area in the unloaded state is a, the overlapping surface areas S00, S01, S10, S11are expressed by Formula 6.

From Formula 6, the sum of the four overlapping surface areas is 4a2and is a constant. Accordingly, the overlapping surface areas S00, S01, S10, S11become known values from Formula 5 and the sum 4a2of the four overlapping surface areas. Due to the above, the unknown displacements Δx, Δy can be calculated from the simultaneous equations of Formula 6.

If the displacements Δx, Δy are calculated, by using these as known values, the displacement Δz that is assumed to be a common value may be corrected to the individual displacements Δz at the respective first electrodes34. This correction can be carried out by, for example, acquiring in advance and utilizing correlations between the displacements Δx, Δy and the four displacements Δz in an environment in which true values of the four displacements Δz can be measured by another means. The acquisition of the correlations may be carried out by machine learning.

In a case in which it is known that the four electrostatic capacitance values corresponding to the respective first electrodes34are approximately equal, i.e., that the displacements Δx and the displacements Δy are near zero, the displacements Δz at the four first electrodes34may be calculated individually by the above method that was described for the case in which Δx, Δy = 0 and Δz ≠ 0. The case in which Δx, Δy = 0 and Δz ≠ 0 is a case in which, for example, the workpiece W that is in a state of being placed on a stand is grasped, and the weight of the workpiece W is not being applied to the contacting surface28. When, from this state, the workpiece W is lifted-up from the stand, mainly the displacements Δx, Δy change while the displacement Δz hardly changes at all. Therefore, the displacement Δz is treated as a known value, and the displacements Δx, Δy can be determined more accurately.

In the present specification, “calculating the respective pressure values of the plurality of pressure detecting positions” includes, in a case of assuming that the displacement Δz is common at plural pressure detecting positions such as the four first electrodes34, treating the pressure value, which is based on the common displacement Δz that is calculated, as the pressure value at the respective pressure detecting positions. Further, “calculating an aggregate pressure value by carrying out calculation of a representative value of the respective pressure values of the plurality of pressure detecting positions” includes, in a case of assuming that the displacement Δz is common at plural pressure detecting positions such as the four first electrodes34, calculating the aggregate pressure value by using the pressure value, which is based on the common displacement Δz that is calculated, as a representative value.

As described above, on the basis of the plural signals that respectively correspond to the plural first electrodes34that include at least one partially-overlapping electrode that is the first electrode34that partially overlaps the second electrode36, the output section12calculates the respective shearing force Fx, Fy values so as to eliminate the effects of pressure on the plural signals.

Operation and effects of the first embodiment are described next.

At the tactile sensor10(seeFIG.3throughFIG.7), the second electrode layer26is configured by the plural second electrodes36in a single layer. Accordingly, the structure and the manufacturing processes of the tactile sensor10can be simplified.

Further, pressure can be detected at the respective positions of the plural first electrodes34by detecting the electrostatic capacitances that change in accordance with the distance between the first electrodes34and the second electrodes36. Moreover, the respective second electrodes36partially overlap with the respective four first electrodes34that are adjacent in the X-axis direction and the Y-axis direction. Therefore, also the shearing forces at the positions of the respective second electrodes36can be detected by detecting the electrostatic capacitances that change in accordance with the overlapping surface areas of these four first electrodes34and the second electrode36.

Moreover, due to the number of the plural second electrodes36being less than the number of the plural first electrodes34, the plural first electrodes34correspond to the one second electrode36. Therefore, the intervals between the plural first electrodes34can be narrowed as compared with a case in which, for example, the plural first electrodes34and the plural second electrodes36are in a one-to-one correspondence. Due thereto, because the number of the plural first electrodes34can be ensured, the resolution of the pressure distribution can be ensured.

In this way, in accordance with the tactile sensor10relating to the first embodiment, shearing forces can be detected, and the resolution of the pressure distribution can be ensured, even by a simple structure and simple manufacturing processes.

Modified examples of the first embodiment are described next.

The tactile sensor10has the36first electrodes34, but the number of the plural first electrodes34may be any number.

The number of the plural second electrodes36may be any number, provided that it is less than the number of the plural first electrodes34.

The plural first electrodes34are preferably arrayed in the form of a matrix along the contacting surface28. However, the first electrodes may be disposed in a form other than a matrix form, provided that the desired pressure distribution is obtained within the contacting surface28.

Second Embodiment

A second embodiment is described next.

FIG.12is a vertical sectional view of the tactile sensor10relating to a second embodiment. In the tactile sensor10relating to the second embodiment, the structure of the second electrode layer26is changed as follows with respect to that of the tactile sensor10relating to the above-described first embodiment (seeFIG.3throughFIG.6).

FIG.13is a plan view of the second electrode layer26ofFIG.12. The second electrode layer26is configured by the one second electrode36that is a single layer. Namely, the second electrode36forms a single island portion. The second electrode36is formed of a conductive rubber for example. This second electrode36is formed in the shape of a flat plate. The second electrode36may be connected to the ground of the substrate16, or may be floating with respect to ground.

FIG.14is a plan view illustrating a state in which the second electrode36and the elastic layer22and the substrate16ofFIG.12are superposed. As example, the number of the plural first electrodes34is36, whereas the second electrode36forms one island portion. Therefore, in the second embodiment, the number of island portions formed by the second electrode36is less than the number of the plural first electrodes34.

As an example, the second electrode36is formed in the shape of a square that is smaller than the contacting surface28(seeFIG.12). This second electrode36is a size that overlaps all of the plural first electrodes34as viewed in plan view. Specifically, the second electrode36is a size such that the first electrodes34, which are lined-up along the outer peripheral portion of the second electrode36among the plural first electrodes34, and the outer peripheral portion of the second electrode36overlap as viewed in a plan view. Due thereto, the first electrodes34that are lined-up along the outer peripheral portion of the second electrode36partially overlap with the second electrode36as viewed in a plan view. Among the plural first electrodes34, the first electrodes34that are positioned at the inner side of the outer peripheral portion of the second electrode36entirely overlap the second electrode36.

In the second embodiment, among the plural first electrodes34, the first electrodes34that partially overlap with the second electrode36correspond to an example of the “plurality of partially-overlapping electrodes that partially overlap with the second electrode”, and the plural signals outputted from these first electrodes34that partially overlap with the second electrode36correspond to an example of the “plurality of partially-overlapping electrode signals”.

At the sensor portion18of the tactile sensor10illustrated inFIG.12, when pressure is applied to the contacting surface28, and the distance d between each first electrode34and the second electrode36changes, the electrostatic capacitance C changes in accordance with this change in the distance d. Further, at the sensor portion18, when shearing force is applied to the contacting surface28, and the surface area A over which the first electrode34(seeFIG.14), which partially overlaps the second electrode36, and the second electrode36overlap one another changes, the electrostatic capacitance C changes in accordance with this change in the surface area A.

The tactile sensor10of this structure is manufactured in the same way as the tactile sensor10relating to the above-described first embodiment (seeFIG.3throughFIG.6).

Further, in the second embodiment, the calculation of the displacements Δx, Δy, Δz is carried out on the basis of an approach similar to that of the case of the first embodiment.

Operation and effects of the second embodiment are described next.

In the tactile sensor10(seeFIG.12throughFIG.14), the second electrode layer26is configured by the one second electrode36that is a single layer. Accordingly, the structure and the manufacturing processes of the tactile sensor10can be simplified.

Further, pressure can be detected at the respective positions of the plural first electrodes34by detecting the electrostatic capacitances that change in accordance with the distances between the first electrodes34and the second electrode36. Moreover, some of the plural first electrodes34, i.e., the first electrodes34that are lined-up along the outer peripheral portion of the second electrode36, partially overlap with the second electrode36as viewed in a plan view. Therefore, also the shearing forces at the positions of the respective first electrodes34, which are lined-up along the outer peripheral portion of the second electrode36, can be detected by detecting the electrostatic capacitances that change in accordance with the overlapping surface areas of these first electrodes34and the second electrode36.

Moreover, due to the number of the second electrodes36being one and being less than the number of the plural first electrodes34, the plural first electrodes34correspond to the one second electrode36. Therefore, the intervals between the plural first electrodes34can be narrowed as compared with a case in which, for example, the plural first electrodes34and the plural second electrodes36are in a one-to-one correspondence. Due thereto, because the number of the plural first electrodes34can be ensured, the resolution of the pressure distribution can be ensured.

In this way, in accordance with the tactile sensor10relating to the second embodiment, shearing forces can be detected, and the resolution of the pressure distribution can be ensured, even by a simple structure and simple manufacturing processes.

Further, because the second electrode36is a single structure, as compared with a case in which the second electrode36is configured by plural members for example, the manufacturing efficiency can be improved, and the number of parts can be reduced.

Modified examples of the second embodiment are described next.

The tactile sensor10has the36first electrodes34, but the number of the plural first electrodes34may be any number.

Although there is the one second electrode36, the number of the second electrodes36may be any number provided that it is less than the number of the plural first electrodes34.

The plural first electrodes34are preferably arrayed in the form of a matrix along the contacting surface28. However, the first electrodes may be disposed in a form other than a matrix form, provided that the desired pressure distribution is obtained within the contacting surface28.

Third Embodiment

A third embodiment is described next.

FIG.15is a vertical sectional view of the tactile sensor10relating to a third embodiment. In the tactile sensor10relating to the third embodiment, the structure of the second electrode layer26is changed as follows with respect to that of the tactile sensor10relating to the above-described first embodiment (seeFIG.3throughFIG.6).

FIG.16is a plan view of the second electrode layer26ofFIG.15. The second electrode layer26is configured by the one second electrode36that is a single layer. The second electrode36is formed from a conductive rubber for example. This second electrode36is formed in the shape of a flat plate. As an example, the second electrode36is formed in a square shape as viewed in plan view. The second electrode36may be connected to the ground of the substrate16(seeFIG.3), or may be floating with respect to ground.

The plural openings38are formed in the second electrode36. The plural openings38pass-through in the plate thickness direction of the second electrode36, i.e., the Z-axis direction. The plural openings38are arrayed in the form of a matrix along the X-Y plane. Namely, the plural openings38are arrayed with the X-axis direction being the length direction and the Y-axis direction being the width direction.

The plural openings38are the same shape, and, as an example, the plural openings38are formed in square shapes as viewed in plan view. The number of the plural openings38is less than the number of the above-described, plural first electrodes34(seeFIG.4). As an example, the plural openings38are arrayed such that there are three thereof in the X-axis direction and three thereof in the Y-axis direction. Namely, the number of the plural openings38is nine. These plural openings38are arrayed at uniform intervals in the X-axis direction and the Y-axis direction, respectively.

FIG.17is a plan view illustrating a state in which the second electrode36and the elastic layer22and the substrate16ofFIG.15are superposed. The second electrode36is a size that overlaps all of the plural first electrodes34as viewed in plan view. Specifically, the second electrode36is a size that is such that all of the plural first electrodes34are contained at the inner side of the outer shape of the second electrode36as viewed in plan view.

The plural openings38are respectively formed so as to partially overlap with the respective four first electrodes34that are adjacent in the X-axis direction and the Y-axis direction, among the plural first electrodes34, as viewed in plan view. Specifically, as viewed in plan view, each of the openings38is positioned at the central portion of four of the first electrodes34, and partially overlaps these four first electrodes34.

In this way, in the third embodiment, all of the plural first electrodes34are contained at the inner side of the outer shape of the second electrode36as viewed in a plan view, and further, all of the plural first electrodes34partially overlap with the openings38. All of the plural first electrodes34partially overlapping the openings38corresponds to all of the plural first electrodes34partially overlapping the second electrode36.

In the third embodiment, all of the plural first electrodes34correspond to an example of “plurality of partially-overlapping electrodes that partially overlap with the second electrode”, and the plural signals that are outputted from the plural first electrodes34correspond to an example of the “plurality of partially-overlapping electrode signals”.

In the sensor portion18of the tactile sensor10illustrated inFIG.15, when pressure is applied to the contacting surface28, and the distance d between each first electrode34and the second electrode36changes, the electrostatic capacitance C changes in accordance with this change in the distance d. Further, at the sensor portion18, when shearing force is applied to the contacting surface28, and the surface area A over which each first electrode34and the second electrode36overlap one another changes, the electrostatic capacitance C changes in accordance with this change in the surface area A.

The tactile sensor10of this structure is manufactured in the same way as the tactile sensor10relating to the above-described first embodiment (seeFIG.3throughFIG.6).

Further, in the third embodiment, the calculation of the displacements Δx, Δy, Δz is carried out on the basis of an approach similar to that of the case of the first embodiment.

Operation and effects of the third embodiment are described next.

In the tactile sensor10(seeFIG.15throughFIG.17), the second electrode layer26is configured by the one second electrode36that is a single layer. Accordingly, the structure and the manufacturing processes of the tactile sensor10can be simplified.

Further, pressure can be detected at the respective positions of the plural first electrodes34by detecting the electrostatic capacitances that change in accordance with the distances between the first electrodes34and the openings38. Moreover, because each of the openings38partially overlaps the respective, four first electrodes34that are adjacent in the X-axis direction and the Y-axis direction, also the shearing forces at the positions of the respective openings38can be detected by detecting the electrostatic capacitances that change in accordance with the overlapping surface areas of these four first electrodes34and the plural openings38.

Moreover, due to the number of the openings38that are formed in the second electrode36being less than the number of the plural first electrodes34, the plural first electrodes34correspond to the one opening38. Therefore, the intervals between the plural first electrodes34can be narrowed as compared with a case in which, for example, the plural first electrodes34correspond one-to-one to the plural openings38. Due thereto, because the number of the plural first electrodes34can be ensured, the resolution of the pressure distribution can be ensured.

In this way, in accordance with the tactile sensor10relating to the third embodiment, shearing forces can be detected, and the resolution of the pressure distribution can be ensured, even by a simple structure and simple manufacturing processes.

Further, because the second electrode36is a single structure that has the plural openings38, as compared with a case in which the second electrode36is configured by plural members for example, the manufacturing efficiency can be improved, and the number of parts can be reduced.

The tactile sensor10has the36first electrodes34, but the number of the plural first electrodes34may be any number.

The number of the second electrodes36may be any number provided that it is less than the number of the plural first electrodes34.

The plural first electrodes34are preferably arrayed in the form of a matrix along the contacting surface28. However, the first electrodes may be disposed in a form other than a matrix form, provided that the desired pressure distribution is obtained within the contacting surface28.

Fourth Embodiment

A fourth embodiment is described next.

FIG.18is a vertical sectional view of the tactile sensor10relating to a fourth embodiment. In the tactile sensor10relating to the fourth embodiment, the structure of the second electrode layer26is changed as follows with respect to that of the tactile sensor10relating to the above-described first embodiment (seeFIG.3throughFIG.6).

FIG.19is a plan view of the second electrode layer26ofFIG.18. The second electrode layer26is configured by the one second electrode36that is a single layer. The second electrode36is formed in the shape of a flat plate. The second electrode36may be connected to the ground of the substrate16, or may be floating with respect to ground. The second electrode36is formed of a conductive rubber for example.

One opening38is formed in the second electrode36. As an example, the opening is formed in the central portion of the second electrode36. The second electrode36is formed in a square shape as viewed in plan view, and the opening38also is formed in a square shape as viewed in plan view.

FIG.20is a plan view illustrating a state in which the second electrode36and the elastic layer22and the substrate16ofFIG.18are superposed. As an example, the number of the plural first electrodes34is36, whereas the one opening38is formed in the second electrode36. Therefore, in the fourth embodiment, the number of the openings38formed in the second electrode36is less than the number of the plural first electrodes34.

The second electrode36is a size that overlaps all of the plural first electrodes34as viewed in plan view. Specifically, the second electrode36is a size that is such that all of the plural first electrodes34are contained at the inner side of the outer shape of the second electrode36as viewed in plan view.

As an example, the opening38is formed in the shape of a square that is smaller than the minimum square that contains all of the central, four first electrodes34that are adjacent in the X-axis direction and the Y-axis direction, as viewed in plan view. The opening38is positioned at the central portion of the central, four first electrodes34as viewed in plan view, and partially overlaps these four first electrodes34. Due thereto, among the plural first electrodes34, the central, four first electrodes34partially overlap with the second electrode36as viewed in plan view. Among the plural first electrodes34, the first electrodes34that are other than the central, four first electrodes34completely overlap the second electrode36.

In the second embodiment, the central, four first electrodes34among the plural first electrodes34correspond to an example of the “plurality of partially-overlapping electrodes that partially overlap with the second electrode”, and the plural signals outputted from these central, four first electrodes correspond to an example of the “plurality of partially-overlapping electrode signals”.

The tactile sensor10of this structure is manufactured in the same way as the tactile sensor10relating to the above-described first embodiment (seeFIG.3throughFIG.6).

In the fourth embodiment, the calculation of the displacements Δx, Δy, Δz is carried out on the basis of an approach similar to that of the case of the first embodiment.

Operation and effects of the fourth embodiment are described next.

In the tactile sensor10(seeFIG.18throughFIG.20), the second electrode layer26is configured by the one second electrode36that is a single layer. Accordingly, the structure and the manufacturing processes of the tactile sensor10can be simplified.

Further, pressure can be detected at the respective positions of the plural first electrodes34by detecting the electrostatic capacitances that change in accordance with the distances between the first electrodes34and the second electrode36. Moreover, the central, four first electrodes34among the plural first electrodes34partially overlap with the opening38that is formed in the center of the second electrode36as viewed in plan view. Therefore, also the shearing forces at the position of the opening38can be detected by detecting the electrostatic capacitances that change in accordance with the overlapping surface areas of these four first electrodes34and the second electrode36.

Moreover, due to the number of the openings38that are formed in the second electrode36being one and being less than the number of the plural first electrodes34, the plural first electrodes34correspond to the one opening38. Therefore, the intervals between the plural first electrodes34can be narrowed as compared with a case in which, for example, the plural first electrodes34correspond one-to-one to the plural openings38. Due thereto, because the number of the plural first electrodes34can be ensured, the resolution of the pressure distribution can be ensured.

In this way, in accordance with the tactile sensor10relating to the fourth embodiment, shearing forces can be detected, and the resolution of the pressure distribution can be ensured, even by a simple structure and simple manufacturing processes.

Further, because the second electrode36is a single structure, as compared with a case in which the second electrode36is configured by plural members for example, the manufacturing efficiency can be improved, and the number of parts can be reduced.

Modified examples of the fourth embodiment are described next.

The tactile sensor10has the36first electrodes34, but the number of the plural first electrodes34may be any number.

Although the one opening38is formed in the second electrode36, the number of the openings38may be any number provided that the number of the openings38is less than the number of the plural first electrodes34.

The plural first electrodes34are preferably arrayed in the form of a matrix along the contacting surface28. However, the first electrodes may be disposed in a form other than a matrix form, provided that the desired pressure distribution is obtained within the contacting surface28.

Although first through fourth embodiments of the technique disclosed in the present application have been described above, the technique disclosed in the present application is not limited to the above, and can of course be implemented by being modified in various ways, other than the above, within a scope that does not depart from the gist thereof.

Note that the disclosure of Japanese Patent Application No. 2020-140395 is, in its entirety, incorporated by reference into the present specification.

All publications, patent applications, and technical standards mentioned in the present specification are incorporated by reference into the present specification to the same extent as if such individual publication, patent application, or technical standard was specifically and individually indicated to be incorporated by reference.