JP7119566B2 - Pressure sensor, pressure sensor module, and robot hand - Google Patents

Description

The present invention relates to pressure sensors using carbon nanotubes.

BACKGROUND ART Conventionally, a pressure sensor is known that uses the properties of carbon nanotubes to measure pressure applied to (a layer containing) carbon nanotubes. For example, in Patent Document 1, an insulating polyvinyl chloride film is attached to a brass test piece, and a carbon nanotube film is attached to it, and on the opposite side of the brass test piece to which the carbon nanotube film is attached A pressure sensor is described that measures pressure from the dimensional change of a carbon nanotube film under pressure using a metal strain gauge attached.

Further, in Patent Document 2, a housing member housing a sensor element body in which a carbon nanotube having a heat-resistant coating film formed thereon is arranged vertically between electrodes, and a carbon nanotube in an opening of the housing member. A pressure sensor is described that has a diaphragm, which is a pressure receiving part that covers the tip, and measures the pressure by detecting a change in resistance value when the carbon nanotube is distorted via the diaphragm when a load is applied. .

Further, Patent Document 3 discloses a thin film layer containing carbon nanotubes and an electrical insulating material, and a first electrode and a second electrode in contact with the thin film layer. A pressure sensitive element is described in which the amount of current increases.

On the other hand, in recent years, the utilization of industrial robots is progressing, and in particular, the development and utilization of collaborative robots that can work alongside humans are being promoted. A hand portion of the collaborative robot is provided with a chucking unit for gripping a work, and generally, a so-called air chuck system is often adopted for this chucking unit.

In the general air chuck type, it is necessary to design a unique chucking unit according to the size, shape, and material of the target work. However, there is a problem that the working robot's original degree of freedom is hindered.

In addition, since the chucking unit of the air chuck type cannot grasp the fluctuation of the gripping load, the collaborative robot has a limited degree of freedom of movement, such as sliding and dropping the workpiece gripped by the collaborative robot. (For example, it is not possible to change the grip of the work while it is being gripped).

In this regard, by arranging a pressure sensor on the manipulator of the robot hand, the gripping load can be constantly measured, and fluctuations in the gripping load can be detected. Controlling the gripping force of the manipulator according to the state would solve the above problems.

However, existing pressure sensors are not suitable for the above applications. For example, in the method of measuring pressure from the dimensional change of the carbon nanotube film due to the load, as in the technique described in Patent Document 1, it is not possible to detect the pressure difference at every several millimeters, which is used for grasping by a robot hand. .

In addition, when the pressure sensor described in Patent Document 2 is used for grasping the gripping state of a workpiece by a robot hand, the bending state of the diaphragm may vary depending on the contact position between the workpiece to be gripped and the diaphragm. It becomes difficult to grasp the grasping load.

Further, as described in Patent Document 3, in a pressure-sensitive element having a thin film layer made of a resin containing carbon nanotubes, the state of contact between the carbon nanotubes inside the thin film layer changes during use as a pressure sensor. So-called hysteresis occurs in responsiveness. For this reason, when used in a gripping system of a robot hand, gripping of a workpiece is hindered.

Japanese translation of PCT publication No. 2006-521212 JP 2015-45544 A Japanese Unexamined Patent Application Publication No. 2013-134208

In view of the circumstances as described above, it is an object of the present invention to provide a pressure sensor capable of accurately measuring pressure fluctuations. Another object of the present invention is to provide a robot hand with a high degree of freedom of motion that can be applied to various workpieces by providing a pressure sensor capable of detecting variations in the gripping load of the target workpiece. .

In order to solve the above problems, a pressure sensor according to the present invention includes a first conductive film made of carbon nanotubes, and a second conductive film made of carbon nanotubes and arranged opposite to the first conductive film. and a resistance detection means for detecting electrical resistance when the first conductive film and the second conductive film are in contact with each other, and based on the resistance value detected by the resistance detection means, A pressure applied to the conductive film is measured.

With the configuration as described above, the pressure is measured from the measured resistance value based on the relationship between the load (F) and the resistance (R) to the pressure sensor (hereinafter also referred to as FR characteristics). Specifically, for example, the pressure may be obtained by calculating "pressure=load/contact area". As described above, a plurality of conductive films made of carbon nanotubes are used, and the resistance is detected by the contact of the conductive films. can have a change width of several kΩ, and a change in the resistance value having relative linearity with respect to the load can be obtained.

When detecting the resistance, it is of course possible to measure the current value flowing through the contact portion of the conductive film and divide the applied voltage by the measured current value. Moreover, since the load can be measured naturally in the above configuration, the pressure sensor may be a load sensor.

In addition, carbon nanotubes can be selected from various lengths ranging from several μm to several hundreds of μm. Can be set according to characteristics.

As described above, it is possible to obtain a pressure sensor that has an arbitrary FR characteristic and can accurately measure variations in applied pressure.

Further, each of the conductive films may be provided on a flexible plate-shaped base material. Further, the substrate may be made of resin. With such a configuration, the shape or pattern of the conductive film on the substrate can be formed in any number and shape according to the application.

Further, the hardness of the base material to which pressure is applied may be 20 or more and 85 or less Shore A hardness measured according to JIS-Z2246. If the hardness value of the base material is too high, it becomes difficult to obtain a minute load response as a pressure sensor. erroneous detection of the contact state may occur. For this reason, it is desirable that at least the substrate on the side to which pressure is applied has a hardness within the above range.

Further, the pressure sensor may further include a support for supporting each of the substrates so that the surfaces on which the first conductive film and the second conductive film are formed face each other. good. By using a support of arbitrary shape, the degree of freedom of the shape of the pressure sensor can be increased.

Further, each base material may be supported so that a predetermined space is formed between the first conductive film and the second conductive film. With such a configuration, the carbon nanotube conductive films do not come into contact with each other in a no-load state, so it is possible to accurately detect the resistance at the beginning of the application of the load.

A dielectric may be provided in the predetermined space, and the first conductive film and the second conductive film may be brought into contact with each other through the dielectric. For example, by interposing an electrolytic solution, dielectric gel, dielectric sheet, etc. between the carbon nanotube conductive films, it is possible to adjust the resistance sensitivity, and the FR characteristics can be improved in the low to high load range. It becomes possible to improve the linearity. Also, by assisting the restorability between the carbon nanotube conductive films, the hysteresis of the pressure sensor can be reduced.

Moreover, the length of the carbon nanotube may be 10 μm or more and 1000 μm or less. The length of the individual carbon nanotubes forming the carbon nanotube conductive film is either too long or too short from the viewpoint of the contact resistance of the carbon nanotubes in the conductive film and the orientation of the carbon nanotubes in the conductive pattern in a specific direction. not desirable. Based on FR characteristics, the carbon nanotubes preferably have a length within the above ranges, more preferably from 100 μm to 500 μm, to control the resistance produced.

Further, each conductive film may have a conductivity of 10 S/cm or more and 1000 S/cm or less. If the conductivity is less than 10 S/cm, the low conductivity makes it difficult to obtain the desired FR characteristics. On the other hand, if it exceeds 1000 S/cm, the resistance change due to the contact of the carbon nanotube conductive film becomes too large, making it difficult to obtain the desired FR characteristics.

Further, each of the pressure sensors may be arranged in the manipulator section of the robot hand and measure the pressure when the robot hand grips the object. In view of the characteristics of the pressure sensor according to the present invention, it is suitable to apply it to such uses.

In order to solve the above problems, a plurality of the above pressure sensors may be arranged to form a pressure sensor module. By using such a pressure sensor module, it is possible to arbitrarily set the range of locations where the pressure is applied and the variation thereof is measured.

Further, in order to solve the above problems, a robot hand may be configured in which the pressure sensor or the pressure sensor module is provided in the manipulator section.

The means described above can be freely combined and implemented as long as there is no technical contradiction.

ADVANTAGE OF THE INVENTION According to this invention, the pressure sensor which can measure a fluctuation|variation of a pressure with sufficient accuracy can be provided. In addition, by providing a pressure sensor capable of detecting variations in the gripping load of a target work, it is possible to provide a robot hand with a high degree of freedom of motion that can be applied to various works.

FIG. 1 is a block diagram schematically showing a configuration example of a pressure sensor according to an application example. FIG. 2A is a schematic perspective view of a pressure sensor element according to an application. FIG. 2B is a cross-sectional view schematically showing a pressure sensor element according to an application example. FIG. 3 is a diagram illustrating a state in which the pressure sensor according to the application example receives a load. FIG. 4 is a graph showing the relationship between the load applied to the pressure sensor and the measured resistance value according to the application example. FIG. 5 is a diagram schematically showing a configuration example of a robot hand according to the embodiment. FIG. 6 is a diagram showing the arrangement of pressure sensors in the pressure sensor module according to the embodiment. FIG. 7 is a flow chart showing the flow of the gripping operation of the robot hand according to the embodiment. FIG. 8A is a first diagram showing an example of a conductive pattern shape according to a modification; FIG. 8B is a second diagram illustrating an example of a conductive pattern shape according to a modification; FIG. 8C is a third diagram illustrating an example of a conductive pattern shape according to a modification; FIG. 8D is a fourth diagram showing an example of a conductive pattern shape according to a modification; FIG. 9A is a first diagram showing an example of the shape of a base material according to a modification. FIG. 9B is a second diagram showing an example of the shape of the base material according to the modification. FIG. 10A is a first diagram according to a modification in which a conductive pattern is formed by a plurality of conductive films; FIG. 10B is a second diagram according to a modification in which a conductive pattern is formed by a plurality of conductive films; FIG. 10C is a third diagram according to a modification in which a conductive pattern is formed by a plurality of conductive films; FIG. 11A is a schematic diagram of a modification in which a conductive pattern is formed using a plurality of conductive films having different conductivities. FIG. 11B is a graph showing the relationship between the load received by the pressure sensor and the measured resistance value according to the modification. FIG. 12A is a first diagram showing a modification of the arrangement pattern of pressure sensor modules. FIG. 12B is a second diagram showing a modification of the arrangement pattern of the pressure sensor modules. FIG. 12C is a third diagram showing a modification of the arrangement pattern of the pressure sensor modules.

An example of an embodiment of the present invention will be described below with reference to the drawings.

<Application example>
(Configuration of application example)
The present invention can be applied, for example, as a pressure sensor as shown in FIG. FIG. 1 is a block diagram schematically showing a configuration example of a pressure sensor 9 according to this application example. The pressure sensor 9 has a pressure sensor element section 91 , a resistance meter 92 and a resistance-pressure conversion section 93 .

2A and 2B are diagrams schematically showing the pressure sensor element portion 91, FIG. 2A being a perspective view of the pressure sensor element portion 91, and FIG. 2B being a sectional view thereof. As shown in FIGS. 2A and 2B, the pressure sensor element portion 91 includes two substrates 912a and 912 provided with conductive films 911a and 911b.
2b is supported by supports 913a and 913b so that the surfaces provided with the conductive films face each other.

An electric wire (not shown) is connected to each of the conductive films 911a and 911b to form a terminal. In this specification, a terminal means a connection part of electric wiring. The other end of each wire is connected to an ohmmeter 92 . Accordingly, when the conductive films 911a and 911b are in contact with each other, current is generated and resistance can be detected.

The conductive films 911a and 911b are formed by entangling a large number of carbon nanotubes, and are sheets made of carbon nanotubes. Although the shape is not particularly limited, it may be, for example, a 5 mm square. Other polygonal or circular shapes may be used, or a grid-like shape may be used.

The carbon nanotubes forming the conductive films 911a and 911b may be metallic carbon nanotubes, and may be either single-walled carbon nanotubes or multi-walled carbon nanotubes. Also, the method for producing carbon nanotubes is not particularly limited, and can be produced by, for example, the CVD method, the super-growth CVD method, the laser ablation method, the DIPS method, the HiPCO method, the Combat method, the arc method, and the like. Also, the length of one carbon nanotube can be, for example, between 10 μm and 1000 μm, preferably between 100 μm and 500 μm.

The thickness of the conductive films 911a and 911b can be, for example, 3 μm to 100 μm. If the thickness is less than 3 μm, the conductivity of the conductive film is lowered, making it difficult to obtain desired FR characteristics. Moreover, if the thickness exceeds 100 μm, the rigidity of the conductive film increases, and the responsiveness to a low load tends to be impaired.

Also, the conductivity of the conductive films 911a and 911b can be, for example, 10 S/cm to 1000 S/cm. If the conductivity is less than 10 S/cm, the low conductivity makes it difficult to obtain the desired FR characteristics. On the other hand, if it exceeds 1000 S/cm, the resistance change due to the contact of the carbon nanotube conductive film becomes too large, making it difficult to obtain the desired FR characteristics.

Each conductive film is formed by, for example, applying a carbon nanotube dispersion (for example, an aqueous solution containing 1 wt% of carbon nanotubes) directly on the substrate or on another flat place, using a known method such as bar coating or spin coating. It can be prepared by coating with a method and drying it. At this time, areas where the carbon nanotube conductive film is not provided may be masked. Incidentally, the electrical conductivity may be adjusted by applying a magnetic field of several T to magnetically orient the carbon nanotubes during the production of the conductive film. Orientation in this way can reduce variations in FR characteristics between individuals, and can also reduce the hysteresis of the pressure sensor itself. Further, for the same purpose, the viscosity of the carbon nanotube dispersion used for forming the conductive film is increased, and the high-viscosity carbon nanotube dispersion is applied to cause orientation (so-called shear orientation) by shearing. good too.

The base materials 912a and 912b can be formed in, for example, a rectangular shape, but may be formed in other polygonal or circular shapes. Further, the substrates 912a and 912b having the same shape may be arranged opposite to each other, but substrates having different materials and shapes may be arranged opposite to each other. An appropriate combination can be selected according to the material and shape of the location where the pressure sensor 9 is used (installed), and if it is used in a robot hand, suitability for a grasped object.

Further, the material of the base materials 912a and 912b can be made of resin, for example, and may be urethane rubber, fluororubber, silicone rubber, nitrile rubber, thermoplastic elastomer, or the like. It is desirable that at least the substrate on the side to which the pressure is applied has a Shore A hardness of 20 or more and 85 or less. If the hardness value of the base material is too high, it becomes difficult to obtain a minute load response as a pressure sensor. erroneous detection of the contact state may occur.

Also, the thickness of the substrates 912a and 912b can be 0.3 mm to 5.0 mm. If it is less than 0.3 mm, the rigidity of the base material will be insufficient and the restoring force will be reduced, so that variations in FR characteristics and an increase in hysteresis are likely to occur. On the other hand, if it exceeds 5.0 mm, the FR characteristic tends to deteriorate in response to a low load.

The supports 913a and 913b are members that support the substrates 912a and 912b such that spaces are created between the conductive films 911a and 911b. The material can be selected from, for example, urethane rubber, fluororubber, silicone rubber, nitrile rubber, thermoplastic elastomer, and the like. The Shore A hardness of the support can be set between 20 and 85, preferably at least equal to or higher than the hardness of the substrate on the side to which pressure is applied. The supports 913a and 913b are deformed by the load similarly to the base materials 912a and 912b. It is preferable to design

(Pressure measurement method)
Next, pressure measurement by the pressure sensor 9 according to this application example will be described. FIG. 3 is a diagram showing a state in which the pressure sensor element portion 91 receives a load, and FIG. 4 is a graph showing FR characteristics. As shown in FIG. 3, when a load is applied to the pressure sensor element portion 91, the base material 912a bends and the conductive film 911a contacts the conductive film 911b. At this time, if a voltage is applied to the conductive films 911a and 911b from a power source (not shown) through electric wires, current flows due to the contact of the conductive films, and resistance is generated.

Then, the resistance is measured by the ohmmeter 92, and the measured resistance value is converted into a pressure value by the resistance-pressure conversion unit 93, based on the load applied to the pressure sensor element unit 91. Pressure is measured. The conversion process to a pressure value may be, for example, a calculation process of "pressure=load/contact area".

Here, when the load on the pressure sensor element portion 91 increases, the conductive film 911a contacts the conductive film 911b more strongly, so the contact area between the conductive films 911a and 911b increases and the conductive film 911a is formed. The number of contact points between the carbon nanotubes and the carbon nanotubes forming the conductive film 911b increases, and the measured resistance value changes (see FIG. 4). Since the resistance value that varies according to the load is measured in this way, it is possible to accurately measure the variation of the load and, in turn, the pressure.

Note that the process of converting the obtained resistance value into the pressure value by the resistance-pressure conversion unit 93 may be performed based on the load obtained from the FR characteristic obtained in advance by a test or the like. To obtain the load from the FR characteristics obtained in advance, for example, a resistance-load calibration curve, a resistance-load conversion table, or the like can be used.

The pressure value obtained by the resistance-pressure conversion unit 93 may be output by output means (not shown). The output means may be, for example, a device that displays pressure values, or communication means that transmits values to other equipment or devices. Also, a combination of a plurality of output methods may be used.

According to this application example, the hysteresis of the pressure sensor can be greatly reduced compared to a pressure-sensitive conductive element in which general conductive particles are dispersed in resin or rubber. When the pressure-sensitive conductive element as described above is subjected to repeated load responses, the dispersed state of the conductive particles changes and the resistance response to the load fluctuates (generally, the hysteresis is ±30% to ±50%). % change). This level of hysteresis causes a reduction in the sensitivity of the FR characteristic, making it difficult to restore the FR characteristic only by correcting the zero point. On the other hand, according to the pressure sensor of this application example, the hysteresis caused by the change in the dispersion state as described above does not occur, and the FR characteristic can be easily restored by performing the zero point correction as necessary. be able to.

<Example>
Another example of the mode for carrying out the present invention will be further described below. However, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are not intended to limit the scope of the present invention.

(Constitution)
FIG. 5 is a diagram schematically showing a configuration example of the robot hand 1 according to this embodiment. As shown in FIG. 5, the robot hand 1 according to this embodiment is a so-called collaborative robot, and has a manipulator section 11, an arm section 12, and a control section 13 as main components.

A pressure sensor module (not shown) in which a plurality of pressure sensors are arranged is arranged on the side of the manipulator part 11 that grips the workpiece W. As shown in FIG. FIG. 6 shows an example of the arrangement of pressure sensors in the pressure sensor module. In this embodiment, the pressure sensor module has 15 pressure sensors arranged in a 3×5 matrix.

The configuration of each pressure sensor of the pressure sensor module is the same as the configuration of the pressure sensor 9 described in the above application example, so detailed description of the configuration will be omitted. A pressure value measured by the pressure sensor is input to the control unit 13 .

Each pressure sensor is produced, for example, by the following method. First, a carbon nanotube dispersion is applied to a base material by a known technique such as bar coating or spin coating so as to form a 5 mm square, and dried at room temperature, for example. At this time, areas where the carbon nanotube conductive film is not provided may be masked. Below, the part in which the conductive film is formed in a base material is also described as a conductive pattern. The content of carbon nanotubes in the conductive pattern after drying is set to 95 wt % or more. If it is less than 95 wt %, the electrical conductivity tends to be impaired, and the desired FR characteristics may not be obtained.

Next, a terminal is provided on the conductive pattern portion formed as described above. Specifically, a conductive paste, a conductive tape, or the like may be used to connect the carbon nanotube and the electric wire. Next, the base material provided with the conductive pattern and the terminals is sized into the predetermined shape of the pressure sensor. In this embodiment, for example, it is a 7 mm square. Then, a sheet composed of the sized conductive film and the base material is arranged so as to face each other and attached to a support. At this time, the space between the facing sheets is set to about 1 mm.

The manipulator part 11 is configured to be openable and closable by actuators (not shown) such as a plurality of servo motors, and grips a workpiece W to be gripped by changing from an open state to a closed state.

The arm portion 12 has, for example, a plurality of movable portions 121a to 121d, each movable portion being rotatable by an actuator (not shown). Thereby, the manipulator section 11 can be moved within a predetermined operating range.

The control unit 13 includes a CPU (processor), a main storage device (memory), an auxiliary storage device (hard disk, etc.), an input device (keyboard, mouse, controller, touch panel, etc.), an output device (liquid crystal display, speaker, etc.), and the like. It is an information processing device that It controls the entire robot hand by inputting/outputting various types of information, performing arithmetic processing, and controlling actuators. The control unit 13 may be configured by a general-purpose computer system.

The control unit 13 controls the manipulator unit 11 and the arm unit 12 according to a program stored in a storage device or by receiving an input from a user, and grips, moves, and releases the work W within the operating range. let it run.

(Gripping operation of the manipulator)
In order for the manipulator section 11 to properly perform the gripping operation according to the properties of the workpiece W, the manipulator section 11 must be properly closed. That is, it is necessary to appropriately control the force (hereinafter also referred to as gripping force) when the manipulator section 11 grips the workpiece W. FIG. For this reason, in the present embodiment, the gripping force is measured by a pressure sensor module installed in the manipulator section 11, and based on this, the actuator that opens and closes the manipulator section 11 is controlled, thereby appropriately gripping the workpiece W. Realize

The gripping force is measured by applying a DC voltage to each pressure sensor constituting the pressure sensor module and calculating the pressure based on the resistance value determined according to the load applied to each pressure sensor. In addition, load movement during gripping of the workpiece W can be detected from fluctuations in the resistance value of adjacent pressure sensors between the pressure sensors arranged in a matrix. That is, when the work W slips, the fact and the slip amount can be detected.

The voltage applied to each pressure sensor is not limited to direct current and may be alternating current. In addition, when the carbon nanotube conductive pattern is regarded as an LCR circuit and the resistance is measured in the AC resonance frequency band (for example, near 100 kHz), there is a tendency to obtain impedance (Z) ≒ resistance (R), so inductance (L ) and capacitance (C) components are minimized. Therefore, from the viewpoint of suppressing variations in measured values, it is desirable to measure the resistance value in the resonance frequency band when applying an AC voltage.

(Work gripping and pressure measurement flow)
Next, based on FIG. 7, the flow of gripping operation and pressure measurement when the robot hand 1 grips the workpiece W in this embodiment will be described. FIG. 7 is a flow chart showing the flow of the gripping operation of the robot hand. As shown in FIG. 7, the control unit 13 of the robot hand 1 grips the workpiece W with the manipulator unit 11 according to a predetermined program or user's input (step S101). Next, the resistance value of each pressure sensor of the pressure sensor module is obtained (step S102), and the gripping force and the amount of slippage of the workpiece W are calculated (step S103). The gripping force and the amount of slippage of the workpiece W are determined based on the measured pressure value and the FR characteristics measured in advance.

Subsequently, it is determined whether or not the workpiece W is properly gripped based on the gripping force and the amount of slippage of the workpiece W calculated in step S103 (step S104). Whether or not the gripping state is appropriate is determined based on a preset gripping force and slip amount control range. Specifically, it is preferable to set a threshold for each value. In addition, the manipulator unit 11 is photographed by a separate camera, and from the photographed image, the deformation of the gripped work W (that is, whether the gripping load is appropriate), the position of the work W (that is, the slippage of the work W). Presence/absence, amount of slippage) may be acquired, and composite determination may be made.

When it is determined in step S104 that the gripping state is not appropriate, the control unit 13 adjusts the output of the actuator associated with the gripping operation of the manipulator unit 11 (step S105). Then, the process returns to step S102 and the subsequent processes are repeated.

On the other hand, if it is determined in step S104 that the gripping state is appropriate, the gripping state is maintained as is, or the next operation is executed (step S106), and this routine is temporarily terminated. Note that this routine may be constantly repeated until an instruction to stop is given.

As described above, according to the robot hand 1 according to the present embodiment, it is possible to grip workpieces W of various shapes, and by detecting slippage during gripping, the workpiece W can be prevented from falling, It is possible to obtain a robot hand capable of performing complicated actions such as changing the grip of the work W.

<Modification 1>
It should be noted that it is also possible to use pressure sensors having configurations other than those of the above embodiments for each pressure sensor that constitutes the pressure sensor module. For example, in the above embodiment, both the conductive pattern and the substrate of the pressure sensor are rectangular, but other shapes are also possible. 8A to 8D are diagrams schematically showing examples of other shapes of conductive patterns provided on a rectangular base material. A hatched portion in the drawing indicates the shape of the conductive pattern. The conductive pattern may be polygonal in other shapes, as shown in FIG. 8A, or circular, as shown in FIG. 8B. Moreover, it may be in a lattice shape as shown in FIG. 8C, or may be in a comb shape as shown in FIG. 8D. Other shapes are also possible.

9A and 9B are diagrams schematically showing other shapes of substrates on which conductive patterns are formed. As in FIGS. 8A-8D, the conductive patterns are indicated by hatching. The substrate may be polygonal in other shapes, as shown in FIG. 9A, or circular, as shown in FIG. 9B.

Moreover, the shapes of the conductive pattern and the base material can be combined arbitrarily. For example, it is possible to form a circular conductive pattern on a regular octagonal base material. Each shape can be appropriately selected based on the shape adaptability when used as a pressure sensor module, the viewpoint of optimizing the FR response, and the like.

<Modification 2>
Further, in each of the above examples, the conductive pattern was formed by one conductive film on one substrate, but the conductive pattern on the substrate may be formed by a plurality of conductive films. good. 10A to 10C schematically show examples in which a plurality of conductive films form a conductive film. As shown in FIGS. 10A, 10B, and 10C, the number and shape of the conductive films to be used are not particularly limited, and any configuration is possible.

In order to improve the gripping pressure detection resolution, there is a method of reducing the size of the pressure sensor, which is a unit unit that constitutes the sensor module. The surface can be divided into a plurality of parts, and the detection resolution can be improved.

Moreover, when forming one conductive pattern with a plurality of conductive films, it is also possible to use conductive films having different conductivities. FIG. 11A is a schematic diagram of a conductive pattern formed using a first conductive film 21 and a second conductive film 22 having different conductivity. FIG. 11B is a graph showing the relationship between the pressure applied to the conductive pattern and the measured resistance. As shown in FIG. 11B, by observing the resistance value measured by the conductive film with different conductivity as a combined resistance, it is possible to arbitrarily adjust the linearity of the FR characteristics in the low load to high load range. can.

<Modification 3>
In each of the above examples, a hollow space (that is, an air layer) was formed between the opposing conductive patterns. may When using an electrolytic solution or a dielectric gel, for example, the support is formed into a hermetic structure. In this way, by interposing the dielectric between the conductive patterns, it is possible to arbitrarily adjust the resistance sensitivity of the conductive patterns, and it is possible to improve the linearity of the FR characteristics in the low load to high load range. can. Also, by assisting the resilience between the conductive patterns, the hysteresis of the pressure sensor can be reduced.

<Modification 4>
In the above embodiment, the pressure sensor module has pressure sensors arranged in a matrix of 3.times.5, but the pressure sensor module can also be configured with an arrangement pattern other than this. Moreover, each pressure sensor that constitutes the pressure sensor module is not limited to a rectangular shape, and an array pattern can be configured with pressure sensors of various shapes. Further, an arrangement pattern may be configured by combining pressure sensors with different shapes and different FR characteristics.

12A to 12C are schematic diagrams showing modifications of the arrangement pattern of the pressure sensor modules, in which each sensor constituting the arrangement pattern is schematically described by a figure. FIG. 12A shows a pressure sensor module in which pressure sensors that are circular in plan view (eg, 7 mm in diameter) are arranged in a circle. FIG. 12B shows a pressure sensor module in which hexagonal (5 mm square equivalent area) pressure sensors in a plan view are arranged in a so-called honeycomb structure. FIG. 12C shows a pressure sensor module in which pressure sensors of different shapes are combined and arranged.

If the target is limited to some extent with respect to the size, shape, material, load fluctuation and load movement detection of the work to be gripped, the arrangement pattern of the pressure sensors can be adjusted appropriately so as to optimize it. Optimal grasping control can be realized.

<Others>
The above description of the embodiments merely exemplifies the present invention, and the present invention is not limited to the above specific forms. Various modifications are possible within the scope of the technical idea of the present invention. For example, in each of the above examples, the pressure measurement was exemplified by calculating "pressure = load / contact area" based on the obtained load, but instead of the FR characteristic, in advance A pressure (P)-resistance (R) characteristic may be obtained in advance to directly obtain a pressure value. Further, in each of the above examples, the value output from the pressure sensor is the pressure value, but the load value may be output instead of the pressure value. That is, the pressure sensor can also be referred to as a load sensor in this paper.

Also, in the above embodiments, a robot hand having one arm and a manipulator was exemplified, but it is of course possible to apply the pressure sensor according to the present invention to a robot having a plurality of arms.

According to one aspect of the present invention, the pressure sensor (9) according to the present invention comprises a first conductive film (911a) made of carbon nanotubes, and a carbon nanotube, arranged to face the first conductive film. a second conductive film (911b), resistance detecting means (92) for detecting electrical resistance when the first and second conductive films are in contact with each other, and the first and second conductive films; and a wiring electrically connected to the resistance detection means, and measures the pressure applied to the conductive film based on the resistance value detected by the resistance detection means.

DESCRIPTION OF SYMBOLS 1... Robot hand 11... Manipulator part 12... Arm part 13... Control part 9... Pressure sensor 911a, 911b... Conductive film 912a, 912b... Base material 913a, 913b. .. Support body W .. Work

Claims (7)

a first conductive film made of carbon nanotubes, and a second conductive film made of carbon nanotubes and arranged to face the first conductive film;
resistance detection means for detecting an electric resistance when the first conductive film and the second conductive film are in contact with each other, and based on the resistance value detected by the resistance detection means, the conductive film A pressure sensor that measures the pressure applied to
Each of the conductive films is provided on a flexible plate-like base material,
A sealed electrolytic solution is interposed between the first conductive film and the second conductive film such that the surfaces on which the first conductive film and the second conductive film are formed face each other. further comprising a support that supports the base material so that a predetermined space is formed for
The resistance detection means detects a change in the electrical resistance according to a change in contact area between the surfaces of the first conductive film and the second conductive film.
A pressure sensor characterized by: The pressure sensor according to claim 1 , wherein the base material is made of resin. The pressure sensor according to claim 1 or 2, wherein the hardness of the base material to which the pressure is applied has a Shore A hardness of 20 or more and 85 or less. The pressure sensor according to any one of claims 1 to 3 , wherein the carbon nanotube has a length of 10 µm or more and 1000 µm or less. The pressure sensor according to any one of claims 1 to 4 , wherein each conductive film has a conductivity of 10 S/cm or more and 1000 S/cm or less. A pressure sensor module comprising a plurality of pressure sensors according to any one of claims 1 to 5 arranged. A robot hand comprising the pressure sensor according to any one of claims 1 to 5 or the pressure sensor module according to claim 6 in a manipulator section.

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