JP2022149380A - Pressure sensor, pressure sensor system, and robot hand - Google Patents

Abstract

To provide a planar pressure sensor capable of detecting a pressure distribution in a one-dimensional direction on a pressure-receiving surface while suppressing loosening of a pressure-sensitive conductive sheet.SOLUTION: A pressure sensor 10 capable of detecting a distribution of force applied to a pressure-receiving surface 18 in a one-dimensional direction comprises a pressure-sensitive conductive layer 11 in which electric resistance changes according to an applied pressure, and a plurality of electrodes 14 arranged in parallel in the one-dimensional direction. The plurality of electrodes is provided only on one surface of the pressure-sensitive conductive layer.SELECTED DRAWING: Figure 1

Description

The present invention relates to a planar pressure sensor capable of detecting a one-dimensional distribution of force applied to a pressure receiving surface. The present invention also relates to a pressure sensor system and a robot hand having such a pressure sensor.

A planar pressure sensor capable of acquiring distribution pressure information is used to detect the position and orientation of a workpiece on a gripping surface when the workpiece is gripped by a robot hand. For example, Patent Literatures 1 and 2 describe a pressure sensor capable of measuring two-dimensional pressure distribution by sandwiching a pressure-sensitive conductive sheet between two sets of electrode rows arranged in a grid pattern. Patent Literature 2 describes that the pressure sensor is attached to a gripping surface of a robot hand for use.

Depending on the work performed by the robot hand, there may be cases where it is not necessary to detect a two-dimensional pressure distribution, and it is sufficient to detect a one-dimensional pressure distribution on the pressure receiving surface. For example, in Patent Document 3, in the operation of inserting a connector attached to the tip of a wire into an insertion hole using a robot hand, a pair of gripping surfaces holding a wire are made parallel to each other and slid in the length direction of the gripping surfaces. It is described to change the rotational orientation of the connector by rolling the wires. In such a linear object rolling operation, it is sufficient if the position of the linear object in the length direction of the gripping surface can be detected. The robot hand described in Patent Document 3 has a pressure sensor that can detect the pressure distribution in the length direction of the gripping surface on at least one of the gripping surfaces. have obtained. In Patent Document 3, as an example of a pressure sensor, a conductive The one with rubber sandwiched is described.

JP 2013-108754 A JP 2019-109213 A JP 2020-192666 A

The pressure sensor described in Patent Document 3, like the pressure sensors described in Patent Documents 1 and 2, has electrodes provided on both sides of the pressure-sensitive conductive sheet. However, when a robot hand holds and rolls the wire, shear stress concentrates on the joint surface between the pressure-sensitive conductive sheet and the electrode, which is the surface where different materials are joined together. Therefore, repeated use of the pressure sensor for a long period of time may damage the joint between the pressure-sensitive conductive sheet and the electrode, causing the pressure-sensitive conductive sheet to sag and cause measurement errors.

The present invention has been made in consideration of the above, and provides a planar pressure sensor capable of detecting pressure distribution in a one-dimensional direction on a pressure receiving surface and capable of suppressing sagging of a pressure-sensitive conductive sheet or the like. intended to provide

A pressure sensor of the present invention is a pressure sensor capable of detecting a one-dimensional distribution of a force applied to a pressure receiving surface, the pressure sensitive conductive layer having an electrical resistance that changes according to the applied pressure; and a plurality of electrodes arranged in parallel in a dimension direction, wherein the plurality of electrodes are provided only on one surface of the pressure-sensitive conductive layer.

Here, to detect the one-dimensional distribution of the force applied to the pressure-receiving surface, in addition to obtaining the distribution of the absolute value of the force, an index corresponding to the force on a one-to-one basis, for example, pressure-sensitive conductive This includes determining the rate of change of layer resistance, permittivity, piezovoltage, and piezoresistance distributions.

This configuration can reduce the number of contact surfaces with electrodes that cause sagging of the pressure-sensitive conductive layer.

Preferably, the pressure-sensitive conductive layer is made of a pressure-sensitive conductive rubber sheet. As a result, it is only necessary to cut the sheet-like material into desired shapes and sizes, so that pressure sensors can be manufactured at low cost even when manufacturing a wide variety of products in small quantities according to the application.

Preferably, the plurality of electrodes are formed on a resin film substrate. This facilitates manufacturing of the pressure sensor.

A pressure sensor system of the present invention includes any one of the above pressure sensors and a control section, the plurality of electrodes are connected to the control section, and the control section applies a predetermined voltage from the plurality of electrodes. A drive electrode to be connected to the ground is selected, and a ground electrode connected to the ground, which is an electrode other than the drive electrode, is selected, and the potential of the drive electrode with respect to the ground is measured. Here, the ground is a potential that serves as a reference for circuit operation.

Another pressure sensor system of the present invention includes any one of the pressure sensors described above and a control section, and among the plurality of electrodes, some electrodes are connected to the control section and other electrodes are connected to ground. The control unit selects drive electrodes to which a predetermined voltage is applied from the electrodes connected to the control unit, and measures the potential of the drive electrodes with respect to the ground.

A robot hand of the present invention is a robot hand capable of holding an object between a pair of gripping surfaces, and includes any one of the above pressure sensors on at least one of the gripping surfaces.

In the pressure sensor of the present invention, electrodes are provided only on one surface of the pressure-sensitive conductive layer. As a result, compared to conventional pressure sensors in which the pressure-sensitive conductive layer is sandwiched between two pairs of electrodes, it is possible to reduce the number of contact surfaces with the electrodes that cause sagging of the pressure-sensitive conductive layer, thereby improving durability and quality. stability is improved.

It is a figure which shows the cross-section of the pressure sensor of one Embodiment. It is a figure showing composition of a pressure sensor system of a 1st embodiment. It is a side view showing the structure of the robot hand of one embodiment. FIG. 4 is a process flow diagram when using the pressure sensor system of the first embodiment; FIG. 4 is a diagram for explaining a method of measuring a ground potential of an even-numbered electrode of the pressure sensor in the first embodiment; A: 2nd electrode measurement, B: 4th electrode measurement. FIG. 4 is a diagram for explaining a method of measuring a ground potential of an odd-numbered electrode of the pressure sensor in the first embodiment; A: 3rd electrode measurement, B: 5th electrode measurement. FIG. 5 is a diagram for explaining a method of obtaining the maximum position of the force applied to the pressure receiving surface from the measured resistance value; FIG. 10 is a diagram for explaining a method of measuring a ground potential of the third electrode of the pressure sensor in the modified example of the first embodiment; It is a figure which shows the structure of the pressure sensor system of 2nd Embodiment. It is a figure which shows the structure of the pressure sensor system of 3rd Embodiment.

A first embodiment of the present invention will be described in order of a pressure sensor, a pressure sensor system, and a robot hand based on FIGS. 1 to 8. FIG.

Referring to FIG. 1, a pressure sensor 10 of this embodiment includes a pressure-sensitive conductive layer made of a pressure-sensitive conductive rubber sheet 11 and a plurality of linear electrodes 14 provided in parallel on the pressure-sensitive conductive rubber sheet. and The electrode 14 is provided only on one side of the pressure-sensitive conductive rubber sheet, and is electrically connected to the pressure-sensitive conductive rubber sheet via a joint surface 17 . The surface of the pressure-sensitive conductive rubber sheet opposite to the electrodes serves as a pressure receiving surface 18 .

The pressure-sensitive conductive rubber sheet 11 is formed by adding conductive particles such as carbon to insulating rubber such as silicone rubber, and when compressed, the conductive particles come into contact with each other to reduce electrical resistance. Using this characteristic, the applied pressure and its distribution can be calculated by measuring changes in electrical resistance at various locations on the pressure-sensitive conductive rubber sheet. Various commercially available products can be used as the pressure-sensitive conductive rubber sheet.

The thickness of the pressure-sensitive conductive rubber sheet 11 is preferably 0.1 mm or more, more preferably 0.3 mm or more. This is because if the pressure-sensitive conductive rubber sheet is too thin, it is more likely to break during use. On the other hand, the thickness of the pressure-sensitive conductive rubber sheet is preferably 2 mm or less, more preferably 1 mm or less. This is because if the pressure-sensitive conductive rubber sheet is too thick, the rate of resistance change with respect to the amount of compression will be small, and the sensitivity of the sensor will be low.

By using a pressure-sensitive conductive rubber sheet as the pressure-sensitive conductive layer, it is only necessary to cut the sheet-like material into the desired shape and size according to the application, even when manufacturing a wide variety of products in small quantities according to the application. , the pressure sensor 10 can be manufactured at low cost.

The electrodes 14 are linear and arranged parallel to each other in the width direction of the electrodes (horizontal direction in FIG. 1). Each electrode is electrically connected to the pressure-sensitive conductive rubber sheet 11 . Preferably, the electrodes are formed on the resin film substrate 13 and form the electrode sheet 12 together with the resin film substrate. If an electrode sheet is used, the electrode sheet and the pressure-sensitive conductive rubber sheet can be laminated with the electrode facing the pressure-sensitive conductive rubber sheet 11, so that the pressure sensor 10 can be manufactured easily.

A known method can be used to form the electrodes 14 on the resin film substrate 13 . For example, on an insulating resin film such as polyimide, a conductive paste may be printed by screen printing or the like to form an electrode pattern. may be etched to form an electrode pattern.

The pressure-sensitive conductive rubber sheet 11 and the electrode 14 are laminated via the joint surface 17 . When the electrode sheet 12 is used, the electrode 14 may simply be placed on the pressure-sensitive conductive rubber sheet, but preferably an anisotropic conductive adhesive is used to bond them together. This is because the pressure-sensitive conductive rubber sheet is less likely to sag when a shearing stress acts on the bonding surface, and the electrical connection between the pressure-sensitive conductive rubber sheet and the electrode can be easily maintained.

Note that FIG. 1 is not drawn to scale. The thickness of the resin film substrate 13 is typically 10-150 μm. The thickness of the electrode 14 is typically 10-150 μm. The width and pitch of the electrodes can be designed according to the required resolution, but in applications where wires such as electric wires are gripped by a robot hand, the width of the electrodes should be about 0.05 to 3 mm and the pitch should be about 0.1 to 6 mm. often.

Referring to FIG. 2, lead wires 16 are led out from each electrode 14 . Although the direction in which the lead wires are led out is not particularly limited, in FIG. A lead wire 16B is led out to the left side of the sensor. Hereinafter, the odd-numbered electrodes 14A are referred to as "odd-numbered electrodes", and the even-numbered electrodes 14B are referred to as "even-numbered electrodes".

When the electrodes 14 are formed on the resin film substrate 13, the electrodes 14 and the lead wires 16 can be formed on one resin film substrate 13 at the same time. In that case, it is preferable to cover the patterned portion of the lead wire 16 with an insulating coat.

A pressure sensor system 20 of this embodiment has a pressure sensor 10 and a controller 21 . The controller 21 has a controller body 22 and an electrode selection circuit 23 . The electrode selection circuit 23 is composed of a first selection section 24 and a second selection section 26 .

The odd electrodes 14A are connected to the first selection portion 24 via lead wires 16A. The first selection unit selects one of the odd-numbered electrodes according to an instruction from the control unit main body 22, and applies a predetermined voltage V _D , for example, 5 V, through a fixed resistor _RD to make it a drive electrode. Alternatively, one or all of the odd-numbered electrodes are collectively selected and grounded to form a ground electrode. In this specification, an electrode to which a predetermined voltage is applied is called a drive electrode, and an electrode connected to the ground is called a ground electrode. The first selection unit can be configured by appropriately combining commercially available components such as a selector that selects one output from many inputs and an analog switch that switches connections.

The even electrodes 14B are connected to the second selection section 26 via lead wires 16B. The second selection unit selects one of the even-numbered electrodes in response to an instruction from the control unit main body 22, and applies a predetermined voltage V _D , for example, 5 V through a fixed resistor _RD to make it a drive electrode. Alternatively, one or all of the even-numbered electrodes are collectively selected and grounded to form a ground electrode. The second selection section can be configured similarly to the first selection section 24 .

The control unit main body 22 instructs the first selection unit 24 and the second selection unit 26 to select the drive electrode and the ground electrode, and scans the drive electrode to determine the electrical characteristics corresponding to the force applied to the pressure receiving surface 18. By measuring, the distribution of the force applied to the pressure receiving surface in the direction in which the electrodes are arranged is obtained. Specifically, the controller body measures the ground potential of the selected drive electrode. Also, the control unit main body performs various calculations. A microcomputer or the like for controlling connection of peripheral devices can be used for the main body of the control unit. The details of the functions of the control unit 21 will be described later.

With reference to FIG. 3, the robot hand 30 of this embodiment has a base 31, a first finger 32 and a second finger 34. As shown in FIG. The robot hand 30 is often used with the base 31 attached to the tip of the arm of an articulated robot. The first finger has a first gripping surface 33 on the surface facing the second finger, and the second finger has a second gripping surface 35 on the surface facing the first finger. By narrowing the distance between the first finger and the second finger, the workpiece can be held between the first gripping surface and the second gripping surface.

The first gripping surface 33 is provided with the pressure sensor 10 . The pressure sensor is attached with adhesive or tape so that the pressure receiving surface 18 faces the second gripping surface, that is, the side that contacts the workpiece, and the linear electrodes are aligned in the lengthwise direction of the first gripping surface (horizontal direction in FIG. 3). It is fixed to the first gripping surface by fixing, attachment by a holding jig, or the like. Although not shown in FIG. 3, lead wires 16 are led out from the pressure sensor to both sides (front and back in FIG. 3) of the first finger portion 32, and the lead wires run along the side surface or the bottom surface of the first finger portion. It extends toward the base portion 31 and is connected to the control portion 21 . Note that the pressure sensor 10 may be provided on both the first gripping surface 33 and the second gripping surface 35 .

Next, how to use the pressure sensor 10, the pressure sensor system 20, and the robot hand 30 of this embodiment will be described.

First, the robot hand 30 grips a workpiece. A work is, for example, a linear object. Examples of linear objects include metal wires, electric wires, glass fibers, optical fibers, dried noodles, roots and stems of plants, fibers and tubes made of synthetic resin, and the like. Next, the distribution of force applied to the pressure receiving surface 18 of the pressure sensor 10 is detected along the flow of FIG.

(S1) First, the even-numbered electrodes 14B are used as drive electrodes to sequentially scan and measure.

2 and 5, a control signal S is transmitted from the control unit main body 22 to the first selection unit 24, and the first selection unit selects the first odd-numbered electrode E1, connects it to the ground, and uses it as the ground electrode. Connect to the controller body. A control signal S is transmitted from the control unit main body to the second selection unit 26, and the second selection unit selects the first even-numbered electrode E2, applies a predetermined voltage _VD through a fixed resistor _RD , and selects it as a drive electrode. Connect to the controller body. The pressure sensor 10 will be in the state of FIG. 5A. The odd electrodes E1 are ground electrodes and the even electrodes E2 are drive electrodes. By measuring the potential difference between the electrodes E2 and E1, the controller body measures the potential of the electrode E2 with respect to the electrode E1, that is, the potential of the electrode E2 with respect to the ground. The potential of the electrode E2 (the potential of the point Y in FIG. 2) changes in the range of 0 to _VD according to the resistance R12 of the pressure-sensitive conductive rubber sheet between the electrodes E2 and E1. A resistance R12 in the pressure-sensitive conductive rubber sheet corresponding to the ground resistance can be obtained.

Next, a control signal S is transmitted from the control unit main body 22 to the first selection unit 24, and the first selection unit selects the next odd-numbered electrode E3, connects it to the ground, and connects it to the control unit main body as a ground electrode. A control signal S is transmitted from the control unit main body 22 to the second selection unit 26, and the second selection unit selects the next even-numbered electrode E4, applies a predetermined voltage _VD via a fixed resistor _RD , and selects the drive electrode. and connect to the control unit main unit. The pressure sensor 10 will be in the state of FIG. 5B. The odd electrodes E3 are ground electrodes and the even electrodes E4 are drive electrodes. The controller body measures the ground potential of the electrode E4 in the same manner as described above, and this potential corresponds to the resistance R34 in the pressure-sensitive conductive rubber sheet.

Similarly, the first selector 24 sequentially selects the odd-numbered electrodes 14A as ground electrodes, the second selector 26 sequentially selects the even-numbered electrodes 14B as drive electrodes, and the controller main body 22 selects the potential of the drive electrodes with respect to the ground. measure.

(S2) As the next step, the odd-numbered electrodes 14A are used as drive electrodes to sequentially scan and measure.

2 and 6, a control signal S is transmitted from the control unit main body 22 to the second selection unit 26, and the second selection unit selects the even-numbered electrode E2, connects it to the ground, and uses it as the ground electrode in the control unit. Connect to the main unit. A control signal S is transmitted from the control unit main body to the first selection unit 24, and the first selection unit selects the odd electrode E3, applies a predetermined voltage _VD via a fixed resistor _RD , and selects the control unit as a drive electrode. Connect to the main unit. The pressure sensor 10 is in the state shown in FIG. 6A. The even electrodes E2 are ground electrodes and the odd electrodes E3 are drive electrodes. By measuring the potential difference between the electrodes E3 and E2, the controller body measures the potential of the electrode E3 with respect to the electrode E2, that is, the potential of the electrode E3 with respect to the ground. Yes.

Next, a control signal S is transmitted from the control unit main body 22 to the second selection unit 26, and the second selection unit selects the next even-numbered electrode E4, connects it to the ground, and connects it to the control unit main body as a ground electrode. A control signal S is transmitted from the control unit main body 22 to the first selection unit 24, and the first selection unit selects the next odd-numbered electrode E5 and applies a predetermined voltage _VD via a fixed resistor _RD to select the drive electrode. and connect to the control unit main unit. The pressure sensor 10 will be in the state of FIG. 6B. The even electrodes E4 are ground electrodes and the odd electrodes E5 are drive electrodes. The controller body measures the ground potential of the electrode E5 in the same manner as described above, and this potential corresponds to the resistance R45 in the pressure-sensitive conductive rubber sheet.

Similarly, the second selector 26 sequentially selects the even-numbered electrodes 14B as ground electrodes, the first selector 24 sequentially selects the odd-numbered electrodes 14A as drive electrodes, and the controller main body 22 selects the potential of the drive electrodes with respect to the ground. measure.

Through the steps S1 and S2 described above, the ground potential is obtained for all the electrodes 14, and the resistance change of the pressure-sensitive conductive rubber sheet between adjacent electrodes can be obtained. Further, since the compressive strain and resistance change of the pressure-sensitive conductive rubber sheet 11 correspond one-to-one, the control unit main body 22 applies the measured ground resistance to the pressure-receiving surface 18 based on the characteristics of the pressure-sensitive conductive rubber sheet 11 . can be converted to the force applied to As a result, a one-dimensional distribution of the force applied to the pressure receiving surface 18 in the direction in which the electrodes are aligned can be obtained. If the absolute value of the force applied to the pressure-receiving surface is not necessary, the above conversion by the control unit body 22 is not performed, and the force applied to the pressure-receiving surface such as the potential of each electrode to the ground or the rate of change of the resistance to the ground is used. It is also possible to obtain only the distribution of the index corresponding to the force obtained one-to-one. Hereinafter, the distribution of the force applied to the pressure receiving surface 18 and the distribution of the index corresponding to the force on a one-to-one basis are collectively referred to as "pressure distribution on the pressure receiving surface".

(S3) Next, the peak position of the pressure distribution on the pressure receiving surface 18 is obtained. In an actual application, it may be desired to know the position where the force applied to the pressure receiving surface 18 is maximum. For example, in the wire rolling operation described in Patent Document 3, it is necessary to know the peak position of the pressure distribution on the pressure receiving surface in order to obtain the position of the wire. With reference to FIG. 7, the rate of decrease in resistance to ground for each electrode is plotted, and the peak position is obtained by interpolating the portion where the rate of decrease is large with a quadratic curve or parabola. In the example shown in FIG. 7, it can be seen that the peak position is slightly closer to electrode 4 than electrode 5 .

In addition, when the workpiece to be gripped by the robot hand 30 is thick, and when measurement values for all electrodes are not required, only the data of discrete electrodes at arbitrary intervals, such as every other electrode or every other electrode, is used. The peak position may be obtained by

By repeating the above steps S1 to S3 at high speed, the position of the workpiece gripped by the robot hand 30 can be continuously monitored.

According to the pressure sensor 10 of the present embodiment, by using a structure in which electrodes are joined to only one side of the pressure-sensitive conductive rubber sheet 11, it is possible to detect the distribution of the force applied to the pressure-receiving surface in the direction in which the electrodes are aligned. The present inventors attached the pressure sensor (electrode width 0.1 mm, electrode pitch 0.2 mm) to the gripping surface of the robot hand, gripped a metal rod with a diameter of 1 mm, and determined the gripping position of the metal rod by the above method. asked. At the same time, the robot hand was photographed with a camera, and the holding position of the metal rod was obtained from the image. When the results obtained by the two methods were compared, the relative error in the gripping position of the metal bar had a standard deviation of 0.06 mm, and sufficient measurement accuracy was obtained with the pressure sensor 10 of this embodiment.

Further, in the pressure sensor 10 of the present embodiment, since there is only one joint surface between the pressure-sensitive conductive rubber sheet 11 and the electrode 14, the pressure-sensitive conductive rubber sheet becomes slack even if the rolling operation is repeated by the robot hand. Hateful. In a durability test in which the metal bar was gripped by a robot hand and repeatedly rolled, the pressure sensor 10 of the present embodiment was superior to the conventional pressure sensor in which electrodes were provided on both sides of a pressure-sensitive conductive rubber sheet. It was confirmed that the product has excellent durability.

Further, in the pressure sensor 10 of the present embodiment, the ground potential of all the electrodes can be measured by switching which of the odd-numbered electrodes and the even-numbered electrodes is used as the ground potential. As a result, even if electrodes are provided only on one side of the pressure-sensitive conductive rubber sheet, the pressure distribution on the pressure-receiving surface can be obtained with the same resolution as the printing pitch of the electrodes. The above-described pressure sensor system prototyped by the present inventors can measure 64 electrodes in 30 ms, and continuously monitor the gripping position of the wire during the wire rolling operation by the robot hand. was made.

Some modifications of the method of using the pressure sensor system 20 of the present embodiment will be described below.

In the above description, both the selected drive electrode and the ground electrode are connected to the controller body 22, and the potential difference between the two is measured to measure the potential of the drive electrode relative to the ground. However, only the selected drive electrode may be connected to the control unit body, and the control unit body may measure the potential of the drive electrode with respect to the ground. However, even in that case, the first selection section 24 or the second selection section 26 must select the ground electrode and form a circuit from the drive electrode through the pressure-sensitive conductive rubber sheet to the ground.

Further, in the above description, the first selection unit 24 and the second selection unit 26 sequentially select the ground electrodes one by one from the odd electrodes 14A or the even electrodes 14B, but the selection method of the ground electrodes is not limited to this. Specifically, for example, when the first selection unit selects one drive electrode from the odd electrodes, the second selection unit selects all of the even electrodes and grounds them. may be used as the ground electrode. In this case, for example, when the electrode E3 is used as the drive electrode as in FIG. 6A, the pressure sensor 10 is in the state shown in FIG. The resistance to ground and the potential to ground of the drive electrode vary depending on the path from the drive electrode to the ground. In FIG. correspond to resistors connected in parallel. However, since the resistance value of the pressure-sensitive conductive rubber sheet 11 abruptly decreases after reaching a certain compressive strain, it is possible that the drive electrode E3 and ground electrodes E6, E8, . . . The effect of the resistance value between Then, while the even-numbered electrodes are collectively set as ground electrodes, the first selection unit sequentially selects the drive electrodes from the odd-numbered electrodes, and the potential of the drive electrodes relative to the ground can be measured. When the odd-numbered electrodes are collectively selected as the ground electrodes, the electrode located at the end, that is, the electrode E1, has a ground electrode only on one side, and the measurement conditions are different from when the other even-numbered electrodes are used as drive electrodes. It may be excluded from the data when obtaining the pressure distribution. The above is the same when the second selection section selects one drive electrode from the even-numbered electrodes and the first selection section collectively selects the ground electrodes from the odd-numbered electrodes.

Furthermore, for example, the first selection unit 24 selects one drive electrode from the odd electrodes, the second selection unit 26 collectively selects all the even electrodes as ground electrodes, and the first selection unit 24 selects Odd-numbered electrodes other than the drive electrodes may be grounded. This is the same when the second selection section selects one drive electrode from the even-numbered electrodes and the first selection section collectively selects the ground electrodes from the odd-numbered electrodes.

Further, in the above description, the step S1 in which the ground electrode is selected from the odd electrodes 14A and the drive electrode is selected from the even electrodes 14B and sequentially measured, and the ground electrode is selected from the even electrodes and the drive electrode is selected from the odd electrodes. and the step S2 of successively measuring were alternately repeated. However, only one of step S1 or step S2 may be repeated. This reduces the resolution of the pressure distribution obtained, but if the object to be detected is large relative to the distance between the electrodes, for example, if the workpiece to be gripped by the robot hand is thick, and the detection resolution can be reduced, the processing speed will be reduced. You get the benefit of going up.

Next, a second embodiment of the pressure sensor system of the present invention will be described with reference to FIG. This embodiment differs from the first embodiment in that the electrode selection circuit consists of one selection section.

Referring to FIG. 9, pressure sensor system 40 of the present embodiment has pressure sensor 10 and controller 41 . The pressure sensor 10 is the same as in the first embodiment. The controller 41 has a controller body 22 and an electrode selection circuit 43 . The electrode selection circuit 43 consists of one selection section 44 .

All the electrodes 14 of the pressure sensor 10 are connected to the selection section 44 via lead wires 16 . The selection unit 44 selects one electrode according to an instruction from the control unit main body 22 and applies a predetermined voltage V _D , for example, 5 V via a fixed resistor _RD to make it a drive electrode. At the same time, one electrode is selected from the electrodes other than the drive electrode, and is grounded by connecting it to the ground.

The control unit body 22 transmits a control signal S to the selection unit 44, and the selection unit 44 selects one drive electrode and one ground electrode and connects them to the control unit body. The drive electrode and the ground electrode are preferably selected adjacent electrodes. If the electrode next to the drive electrode is selected as the ground electrode, the pressure sensor 10 will be in the same state as in FIGS. The controller main body measures the potential of the drive electrode with respect to the ground by measuring the potential difference between the drive electrode and the ground electrode.

Then, the measurement of the drive electrode is repeated while sequentially changing the drive electrode and the ground electrode to be selected. All the electrodes 14 may be sequentially selected as the drive electrodes, or if the workpiece to be gripped by the robot hand 30 is thicker than the electrode spacing, several electrodes may be sequentially selected. For example, every other drive electrode may be selected, or every two or more electrodes may be selected.

Various modifications are possible in the method of using the pressure sensor system 40 of the present embodiment as in the first embodiment. For example, only the drive electrodes may be connected to the control unit body 22, and the control unit body may measure the potential of the drive electrodes with respect to the ground. Further, for example, the selection unit 44 may collectively select the electrodes other than the drive electrodes as the ground electrodes.

A third embodiment of the pressure sensor system of the present invention will now be described with reference to FIG. This embodiment differs from the first embodiment in that one of the odd-numbered electrodes and the even-numbered electrodes is collectively selected as the drive electrode, and the other is sequentially selected as the ground electrode.

Referring to FIG. 10, pressure sensor system 50 of the present embodiment has pressure sensor 10 and control unit 51 . The pressure sensor 10 is the same as in the first embodiment. The controller 51 has a controller body 22 and an electrode selection circuit 53 . The electrode selection circuit 53 is composed of a first selection section 54 and a second selection section 56 .

The odd electrodes 14A are connected to the first selection portion 54 via lead wires 16A. The first selection unit 54 collectively selects the odd-numbered electrodes according to an instruction from the control unit main body 22, and applies a predetermined voltage V _D , for example, 5 V through a fixed resistor _RD to make them drive electrodes. Alternatively, one of the odd-numbered electrodes is selected and grounded to be used as a ground electrode.

The even electrodes 14B are connected to the second selection portion 56 via lead wires 16B. The second selection unit 56 collectively selects the even-numbered electrodes according to an instruction from the control unit main body 22, and applies a predetermined voltage V _D , for example, 5 V through a fixed resistor _RD to make them drive electrodes. Alternatively, one of the even-numbered electrodes is selected and connected to the ground as a ground electrode.

The method of using the pressure sensor system 50 of this embodiment is as follows.

A control signal S is transmitted from the control unit main body 22 to the first selection unit 54, and the first selection unit collectively selects the odd-numbered electrodes, applies a predetermined voltage _VD through the fixed resistor _RD , and selects the drive electrodes. , and one of the drive electrodes is connected to the main body of the controller. A control signal S is transmitted from the control unit main body to the second selection unit 56, and the second selection unit selects the first even-numbered electrode, connects it to the ground, and connects it to the control unit main body as the ground electrode. The controller main body measures the potential of the drive electrode relative to the ground by measuring the potential difference between the connected drive electrode and the ground electrode.

A control signal S is transmitted from the control unit main body 22 to the second selection unit 56, and the second selection unit selects the next even-numbered electrode, connects it to the ground, and connects it to the control unit main body as the ground electrode. At this time, the first selection section 54 keeps all the odd-numbered electrodes as drive electrodes. The first selection unit may or may not change the drive electrodes connected to the control unit main body. It is preferable to change the drive electrode that connects to the body. The controller main body measures the potential of the drive electrode with respect to the ground by measuring the potential difference between the drive electrode and the ground electrode.

Similarly, while the second selection unit 56 sequentially selects the even-numbered electrodes 14B as the ground electrodes, the control unit body repeats measurement of the drive electrodes.

As a next step, the second selection unit 56 collectively selects the even electrodes 14B and applies a predetermined voltage _VD via the fixed resistor _RD to make them drive electrodes, and the first selection unit 54 selects the odd electrodes 14B. While sequentially selecting 14A as the ground electrode, the main body of the control unit repeats the measurement of the drive electrode. As a result, the potential of the drive electrodes relative to the ground can be obtained when all the electrodes 14 are grounded one by one. By repeating the above steps at high speed, the position of the workpiece gripped by the robot hand 30 can be continuously monitored.

Various modifications are also possible in the method of using the pressure sensor system 50 of the present embodiment, as in the first embodiment. For example, only the drive electrodes may be connected to the control unit body 22, and the control unit body may measure the potential of the drive electrodes with respect to the ground. Further, for example, in the above description, the step of collectively selecting the odd electrodes 14A as the drive electrodes and sequentially selecting the even electrodes 14B as the ground electrodes, and the step of collectively selecting the even electrodes as the drive electrodes and sequentially selecting the odd electrodes. Although the step of selecting the ground electrode is alternately repeated, only one of the two steps may be repeated. This reduces the resolution of the pressure distribution obtained, but if the object to be detected is large relative to the distance between the electrodes, for example, if the workpiece to be gripped by the robot hand is thick, and the detection resolution can be reduced, the processing speed will be reduced. You get the benefit of going up.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the technical scope of the invention.

For example, in the pressure sensor 10 of the above embodiment, the pressure-sensitive conductive rubber sheet 11 is used as the pressure-sensitive conductive layer. You may However, in that case, a printing machine is required, and a printing technique for obtaining a smooth pressure-receiving surface is required. Therefore, from the viewpoint of the cost for high-mix low-volume production and the ease of manufacturing the pressure sensor, it is better to use the pressure-sensitive conductive rubber sheet.

Further, for example, in the above embodiment, the number of selectors connected to a plurality of electrodes is one or two, but the number of selectors is not limited to this. When the number of selectors is increased, a large number of resistance values can be detected with one control signal sent from the control unit main body to each selector, so the pressure distribution of the entire pressure sensor can be detected more quickly.

10 pressure sensor 11 pressure-sensitive conductive rubber sheet (pressure-sensitive conductive layer)
REFERENCE SIGNS LIST 12 electrode sheet 13 resin film substrate 14 electrode 14A odd-numbered electrode 14B even-numbered electrode 16 lead wire 16A odd-numbered lead wire 16B even-numbered lead wire 17 joint surface 18 pressure receiving surface 20 pressure sensor system 21 control Part 22 Control Part Body 23 Electrode Selection Circuit 24 First Selection Part 26 Second Selection Part 30 Robot Hand 31 Base 32 First Finger 33 First Gripping Surface 34 Second Finger 35 Second Gripping Surface 40 Pressure Sensor System 41 Control Part 43 Electrode selection circuit 44 Selection part 50 Pressure sensor system 51 Control part 53 Electrode selection circuit 54 First selection part 56 Second selection part E1 to E6 Electrodes R12, R23, R34, R36, R45 Resistance _RD resistance S Control signal V _D drive voltage

Claims (14)

A pressure sensor capable of detecting a one-dimensional distribution of force applied to a pressure receiving surface,
a pressure-sensitive conductive layer whose electrical resistance changes in response to applied pressure;
and a plurality of electrodes arranged in parallel in the one-dimensional direction,
The plurality of electrodes are provided only on one surface of the pressure-sensitive conductive layer,
pressure sensor. The pressure-sensitive conductive layer is made of a pressure-sensitive conductive rubber sheet,
A pressure sensor according to claim 1 . wherein the plurality of electrodes are formed on a resin film substrate;
The pressure sensor according to claim 1 or 2. Having a pressure sensor and a control unit according to any one of claims 1 to 3,
The plurality of electrodes are connected to the control unit,
The control unit
selecting a driving electrode to which a predetermined voltage is applied from the plurality of electrodes;
Selecting a ground electrode connected to the ground, which is an electrode other than the drive electrode;
measuring the ground potential of the drive electrode;
pressure sensor system. The control unit
sequentially selecting the drive electrodes to which a predetermined voltage is applied from the plurality of electrodes;
sequentially or collectively selecting the ground electrodes other than the drive electrodes, which are connected to the ground;
measuring the ground potential of the drive electrode;
5. The pressure sensor system of claim 4. The control unit measures a potential difference between the drive electrode and one of the ground electrodes to measure the potential of the drive electrode relative to the ground.
6. A pressure sensor system according to claim 5. The control unit has a first selection unit to which odd-numbered electrodes among the plurality of electrodes are connected, and a second selection unit to which even-numbered electrodes are connected,
one of the first selection unit and the second selection unit sequentially selects the drive electrodes, and the other selects the ground electrodes sequentially or collectively;
7. A pressure sensor system according to claim 5 or 6. The control unit comprises a step in which the first selection unit sequentially selects the drive electrodes and the second selection unit selects the ground electrodes sequentially or collectively; and the first selection unit sequentially selects the ground electrodes. Alternatively, the step of selecting all at once and sequentially selecting the drive electrodes by the second selection unit is alternately performed.
The pressure sensor system according to claim 7. The control unit
sequentially selecting the ground electrode connected to the ground from the plurality of electrodes;
collectively selecting the drive electrodes, which are electrodes other than the ground electrode and to which a predetermined voltage is applied;
measuring the ground potential of the drive electrode;
5. The pressure sensor system of claim 4. The control unit measures a potential difference between one of the drive electrodes and the ground electrode to measure the potential of the drive electrode relative to the ground.
10. The pressure sensor system of Claim 9. The control unit has a first selection unit to which odd-numbered electrodes among the plurality of electrodes are connected, and a second selection unit to which even-numbered electrodes are connected,
One of the first selection unit and the second selection unit sequentially selects the ground electrodes, and the other selects the drive electrodes collectively.
A pressure sensor system according to claim 9 or 10. The control unit comprises a step in which the first selection unit sequentially selects the ground electrodes and the second selection unit collectively selects the drive electrodes, and the first selection unit collectively selects the drive electrodes. selecting and sequentially selecting the ground electrode by the second selection unit;
12. The pressure sensor system of claim 11. Having a pressure sensor and a control unit according to any one of claims 1 to 3,
Some electrodes among the plurality of electrodes are connected to the control unit, and other electrodes are connected to the ground,
The control unit
selecting a driving electrode to which a predetermined voltage is applied from the electrodes connected to the control unit;
measuring the ground potential of the drive electrode;
pressure sensor system. A robot hand capable of gripping an object with a pair of gripping surfaces,
At least one of the gripping surfaces is provided with the pressure sensor according to any one of claims 1 to 3,
robot hand.

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