Tactile sensor and sensing system

Abstract

This tactile sensor comprises a pressure-sensitive section. The pressure-sensitive section includes magnetically responsive particles. The tactile sensor also comprises a measurement unit for measuring a response amount corresponding to a change in the density distribution of the magnetically responsive particles caused by external force applied to the pressure-sensitive section.

Description

Tactile sensors and sensing systems

[0001] The present invention relates to a tactile sensor and a sensing system.

[0002] In recent years, automation using robots has been promoted to improve productivity and alleviate labor shortages. In particular, attention has been focused on replacing manual labor with robotic work. As a result, there is a growing demand for tactile sensors that can detect the force applied by a robot to the object being worked on. Because tactile sensors come into physical contact with the object, there is a risk of failure due to deterioration. For this reason, ease of replacement is considered important for tactile sensors.

[0003] For example, WO2019 / 049888 discloses a tactile sensor that includes a non-magnetic flexible layer formed on a substrate, a magnetic flexible layer in which unmagnetized particles having a higher magnetic permeability than that of the non-magnetic flexible layer are dispersed and supported by the non-magnetic flexible layer, a coil formed on the substrate whose inductance changes based on the displacement of the particles due to an external force acting on the magnetic flexible layer, and an inductance measurement circuit that measures the change in inductance of the coil.

[0004] The tactile sensor of WO2019 / 049888 measures the amount of displacement, so there are limitations to the measurement sensitivity.

[0005] An object of the present invention is to improve the measurement sensitivity of a tactile sensor.

[0006] One aspect of the present invention is a tactile sensor comprising a pressure-sensitive unit that contains magnetically responsive particles, and a measuring unit that measures a response amount corresponding to a change in density distribution of the magnetically responsive particles caused by an external force applied to the pressure-sensitive unit.

[0007] 2B is a block diagram showing the configuration of a tactile sensor system of the present embodiment; FIG. 2C is a diagram showing the configuration of a tactile sensor of the present embodiment; FIG. 2D is a cross-sectional view of the tactile sensor of FIG. 2A taken along dashed line C1; FIG. 2E is an explanatory diagram of a measurement process of the present embodiment; FIG. 2F is a diagram showing an example of a screen displaying measurement results of the present embodiment; FIG. 2G is a diagram showing the configuration of a tactile sensor of modified example 1; FIG. 2H is a cross-sectional view of a pressure-sensitive part of modified example 2; FIG. 2I is a diagram showing an example of application example 4 of modified example 3; FIG. 2J is a diagram showing an example of application example 6 of modified example 3.

[0008] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings for explaining the embodiment, the same components are generally designated by the same reference numerals, and repeated description thereof will be omitted.

[0009] (1) Configuration of the tactile sensor system The configuration of the tactile sensor system will be described. Fig. 1 is a block diagram showing the configuration of the tactile sensor system of this embodiment. Fig. 2 is a configuration diagram of the tactile sensor of this embodiment. Fig. 3 is a cross-sectional view of the tactile sensor of Fig. 2A taken along the dashed dotted line C1. Fig. 2A is a perspective view of the tactile sensor 1. Fig. 2B is an XY plan view of the measurement unit 11.

[0010] As shown in FIG. 1 , the tactile sensor system includes a tactile sensor 1 and a display device 2 .

[0011] 1 to 3, the tactile sensor 1 includes a pressure-sensing unit 10, a measurement unit 11, a control unit 12, a power supply 13, and a cover 14. The pressure-sensing unit 10, the cover 14, the measurement unit 11, and the control unit 12 are stacked along the Z axis (FIG. 2A).

[0012] The pressure-sensitive unit 10 is configured to react in response to an external force applied from outside the tactile sensor 1. Specifically, the pressure-sensitive unit 10 includes a magnetic layer but does not include a non-magnetic layer. The magnetic layer includes magnetically responsive particles. The magnetically responsive particles are in a foamed state. The magnetic layer is a composite material mixture of a base material and a magnetically responsive material. The pressure-sensitive unit 10 is formed by dispersing the magnetically responsive material in the base material.

[0013] The base material is a predetermined flexible material. The base material may be, for example, at least one of the following: polyurethane foam; silicone elastomer.

[0014] A magnetically responsive material is a base material mixed with magnetically responsive particles at a certain weight ratio. The magnetically responsive particles are fine particles of a magnetic material (e.g., iron) and a conductor (e.g., aluminum, copper, or carbon). The magnetically responsive particles have the property of changing a magnetic field. This property is determined by the type, diameter, and strength of the magnetic field to which the magnetically responsive particles are subjected.

[0015] Magnetically responsive materials have the property of affecting magnetic fields. When an external force is applied to a magnetically responsive material, the material is compressed due to the influence of the external force. When the magnetically responsive material is compressed, the density distribution of the magnetically responsive particles inside the magnetically responsive material changes. When the density distribution of the magnetically responsive particles changes, the magnetic field also changes.

[0016] The measuring unit 11 is configured to measure the magnitude of an external force (hereinafter referred to as "external force acting amount") at each position on the pressure-sensing unit 10 based on changes in the density distribution of the magnetically responsive material. Specifically, it has a measuring element 111 and a measuring circuit 112. The measuring element 111 has a coil 1111 and a capacitor 1112. The coil 1111 and the capacitor 1112 are connected in parallel to the measuring circuit 112. In other words, the coil 1111, the capacitor 1112, and the measuring circuit 112 form an LC parallel resonant circuit. The measuring circuit 112 passes an AC current through the coil 1111 and the capacitor 1112. As a result, the impedance becomes infinite at a certain frequency, causing a resonance phenomenon between the coil 1111 and the capacitor 1112. The measuring circuit 112 utilizes this resonance phenomenon to measure the change in inductance of the coil 1111 (hereinafter referred to as "inductance change amount" ΔL).

[0017] The control unit 12 is configured to calculate a physical quantity based on the response quantity (for example, the inductance change quantity ΔL) measured by the measurement unit 11. The physical quantity is the amount of external force acting on each position of the pressure-sensing unit 10. The physical quantity includes, for example, at least one of the following: Newton force [N]; pressure [Pa]; and pressing length [cm].

[0018] The control unit 12 is configured to generate a display signal for displaying the physical quantity calculated by the control unit 12 on the display device 2 and to transmit the display signal to the display device 2 .

[0019] The power supply 13 is configured to supply power to the measurement unit 11 and the control unit 12 .

[0020] The cover 14 is located between the pressure-sensing unit 10 and the measuring unit 11. The cover 14 is configured to prevent an external force applied to the pressure-sensing unit 10 from acting on the measuring unit 11. The material of the cover 14 includes, for example, at least one of the following: Acrylic resin PLA (Poly-Lactic Acid) resin ABS (Acrylonitrile Butadiene Styrene) resin Polyethylene resin Polyethylene terephthalate resin

[0021] The display device 2 is connected to the control unit 12 by wire or wirelessly. The display device 2 is configured to display an image (for example, an image showing a physical quantity calculated by the control unit 12) according to a display signal transmitted from the control unit 12. The display device 2 is, for example, at least one of the following: - A display (for example, a liquid crystal display or an organic EL (Electro-Luminescence) display) - A personal computer - A smartphone - A tablet

[0022] (2) Measurement Process The measurement process of this embodiment will be described. Fig. 4 is an explanatory diagram of the measurement process of this embodiment. Fig. 5 is a diagram showing an example of a screen displaying the measurement results of this embodiment.

[0023] 4, when an external force F is applied to the pressure-sensitive unit 10, the density distribution of the magnetically responsive material contained in the magnetic layer 101 changes (FIG. 4A). The change in the density distribution of the magnetically responsive material changes the magnetic field H (FIG. 4B). The change in the magnetic field H changes the response (resonance frequency) of the measuring element 111.

[0024] In this case, the inductance change ΔL of the coil 1111 is expressed by Equation 1. f...resonant frequency C...capacitance of the capacitor 1112 L ０ ...Inductance of the coil 1111 when not resonating (hereinafter referred to as "initial inductance")

[0025] The measurement circuit 112 measures the inductance change amount ΔL based on the resonant frequency of the resonance of the coil 1111 and the capacitor 1112 based on Equation 1. The control unit 12 calculates the amount of external force acting on the pressure-sensing unit 10 based on the inductance change amount ΔL measured by the measurement circuit 112. The control unit 12 generates a display signal for displaying an image showing the calculation result of the physical amount.

[0026] 5A , when an external force is applied to an area X1Y2 of the pressure-sensitive unit 10, the control unit 12 calculates the amount of external force acting on each position of the pressure-sensitive unit 10. The control unit 12 generates a display signal for displaying an image showing the calculation result, and transmits the display signal to the display device 2.

[0027] As shown in Fig. 5B, the display device 2 displays an image corresponding to the display signal. The image includes a simulated image of the pressure-sensitive unit 10. The simulated image is divided into multiple regions (four regions in Fig. 5B). The simulated image is displayed in a display mode (e.g., at least one of a color and a pattern) according to the calculation result of the control unit 12 (i.e., the amount of external force acting at each position on the pressure-sensitive unit 10).

[0028] (3) Summary of the Present Embodiment According to the present embodiment, the response amount corresponding to the change in density distribution of the magnetically responsive particles is measured, thereby improving the sensitivity of the tactile sensor 1.

[0029] According to this embodiment, the response amount (inductance change amount ΔL) may be measured using an LC parallel resonant circuit formed by the coil 1111 and the capacitor 1112. This allows the accuracy and speed of the tactile sensor 1 to be improved.

[0030] According to this embodiment, the magnetically responsive particles may be in a foamed state, which can further improve the sensitivity of the tactile sensor 1.

[0031] According to this embodiment, the pressure-sensitive section 10 does not need to include a non-magnetic layer, which can further improve the sensitivity of the tactile sensor 1.

[0032] According to this embodiment, a control unit 12 may be provided that calculates a physical quantity based on the response amount, thereby making it possible to obtain a desired physical quantity.

[0033] According to this embodiment, the physical quantity may be the amount of external force acting on each position of the pressure-sensitive section 10. This makes it possible to obtain the distribution of the amount of external force acting on the pressure-sensitive section 10.

[0034] According to this embodiment, a cover 14 may be provided between the pressure-sensing unit 10 and the measuring unit 11. This can prevent damage to the measuring unit 11 due to external forces.

[0035] (4) Modifications A modification of this embodiment will be described.

[0036] (4-1) Modification 1 Modification 1 of this embodiment will be described. Modification 1 of this embodiment is an example in which the measuring element is a magnet and a Hall element.

[0037] (4-1-1) Configuration of the Tactile Sensor System of Modification 1 The following describes the configuration of the tactile sensor system of Modification 1. FIG.

[0038] 6, the tactile sensor 1 includes a pressure-sensitive unit 10, a measurement unit 11, a control unit 12, a power supply 13, and a cover 14. The pressure-sensitive unit 10, the control unit 12, the power supply 13, and the cover 14 are the same as those in FIG.

[0039] The measuring unit 11 is configured to measure the amount of external force acting on each position of the pressure-sensing unit 10 based on a change in the density distribution of the magnetically responsive material. Specifically, the measuring unit 11 has a measuring element 111 and a measuring circuit 112. The measuring element 111 has a magnet 1113 and a Hall element 1114.

[0040] The Hall element 1114 is connected to the measurement circuit 112. The Hall element 1114 generates a voltage corresponding to the magnetic field generated by the magnet 1113.

[0041] The measurement circuit 112 measures the amount of change ΔB in the magnetic field (hereinafter referred to as the "magnetic field change amount") of the Hall element 1114. The magnetic field change amount ΔB is an example of a response amount.

[0042] (4-1-2) Measurement Process of Modified Example 1 The measurement process of modified example 1 will be described.

[0043] 4, when an external force F is applied to the pressure-sensing unit 10, the density distribution of the magnetically responsive material contained in the magnetic layer 101 changes (FIG. 4A). The change in the density distribution of the magnetically responsive material changes the magnetic field H (FIG. 4B). The change in the magnetic field H changes the response of the measuring element 111 (magnetic field B of the magnet 1113).

[0044] The change ΔB in the magnetic field B in this case is expressed by Equation 2: ΔB = b(V) - b(V ０ ) ... (Equation 2) b()... A function of the magnetic field with voltage as a variable V... The voltage of the Hall element 1114 when an external force F is applied to the pressure-sensing unit 10 V ０ ...Voltage of the Hall element 1114 when no external force F is applied to the pressure-sensitive section 10

[0045] The measurement circuit 112 measures the magnetic field change amount ΔB based on Equation 2. The control unit 12 calculates the amount of external force acting on the pressure-sensing unit 10 by the external force F at each position on the pressure-sensing unit 10 based on the magnetic field change amount ΔB measured by the measurement circuit 112. The control unit 12 generates a display signal for displaying an image showing the calculation result of the physical amount.

[0046] (4-1-3) Summary of Modification 1 According to Modification 1, the response amount (magnetic field change amount ΔB) may be measured using the magnet 1113 and the Hall element 1114. This makes it possible to measure the action vector of the external force in addition to the amount of the external force.

[0047] (4-2) Modification 2 Modification 2 of this embodiment will be described. Modification 2 of this embodiment is an example in which the pressure-sensitive section 10 is divided into at least two regions.

[0048] (4-2-1) Configuration of Pressure Sensing Unit of Modification 2 The configuration of the pressure sensing unit 10 of Modification 2 of this embodiment will be described.

[0049] As shown in Figure 7, the pressure-sensitive section 10 includes a high-density region 10a and a low-density region 10b.

[0050] The high density region 10a contains magnetically responsive particles at a higher density than the low density region 10b. That is, the pressure-sensitive part 10 has at least two magnetic layers containing magnetically responsive particles with different densities.

[0051] (4-2-2) Summary of Modification 2 According to Modification 2, the high-density region 10a and the low-density region 10b have different responsiveness to external forces. This makes it possible to realize a tactile sensor 1 in which the sensitivity differs depending on the region of the pressure-sensitive section 10.

[0052] (4-3) Modification 3 Modification 3 of this embodiment will be described. Modification 3 of this embodiment is an example of the use of the tactile sensor 1.

[0053] (4-3-1) Application Example 1 The following describes application example 1. Application example 1 is an example in which the tactile sensor 1 is placed on a car seat.

[0054] Specifically, the tactile sensors 1 are placed on the vehicle seat (e.g., the seat surface and backrest). The tactile sensors 1 placed on the seat surface detect body movement in a direction perpendicular to the seat surface (e.g., movement of the seat occupant's waist). The tactile sensors 1 placed on the backrest detect body movement in the direction of travel of the vehicle. The control unit 12 adds up the body movement in the vertical direction and the body movement in the direction of travel to calculate the body movement of the entire body as the amount of external force acting.

[0055] According to the first application example, the accuracy of detecting the body movement of the seat occupant can be improved.

[0056] In Application Example 1, an acceleration sensor may also be used. The acceleration sensor measures vibrations of the vehicle. The control unit 12 may calculate the body movement, pulse, and heart rate of the vehicle based on the vertical body movement measured by the tactile sensor 1 and the vibrations measured by the acceleration sensor.

[0057] (4-3-2) Application Example 2 The following describes application example 2. Application example 2 is an example in which the tactile sensor 1 is disposed on the end effector of a robot that grasps an object.

[0058] In the second application example, the "target object" is an object to be grasped by the robot.

[0059] Specifically, the tactile sensor 1 is placed in the chuck of the robot's end effector. In this case, the pressure-sensing unit 10 is molded to match the shape of the target object. There may be multiple measuring elements 111. When the chuck is closed, the tactile sensor 1 comes into contact with the target object, and the object is grasped by the robot, the control unit 12 calculates the pressure generated when the robot and the target object come into contact as the amount of external force acting. The control unit 12 is connected to the robot's controller.

[0060] According to the second application example, the pressure-sensitive unit 10 is flexible and can conform to the shape of the target object, allowing the robot to firmly grasp the target object without damaging it.

[0061] (4-3-3) Application Example 3 A description will now be given of application example 3. Application example 3 is an example in which the tactile sensor 1 is disposed in factory automation (hereinafter referred to as "FA") equipment.

[0062] In the third application example, the FA device includes, for example, a collaborative robot. The "target object" is an object that is handled by the FA device.

[0063] Specifically, the tactile sensor 1 is placed in the housing of the FA equipment. In this case, the pressure-sensitive unit 10 is shaped to match the shape of the target object. There may be multiple measuring elements 111. When the tactile sensor 1 comes into contact with the target object, the tactile sensor 1 detects contact between the FA equipment and the target object from the deformation of the pressure-sensitive unit 10. The control unit 12 is connected to a controller of the FA equipment.

[0064] According to the third application example, it is possible to expand the area in which contact between the FA device and the target object can be detected, and also to improve the response speed to the contact.

[0065] (4-3-4) Application Example 4 Application example 4 will be described. Application example 4 is an example in which the tactile sensor 1 is arranged on a game controller. FIG. 8 is a diagram showing an example of application example 4 of modification example 3.

[0066] Specifically, the tactile sensor 1 is placed in a game device (for example, a game controller or game console). In this case, the pressure-sensitive unit 10 is molded to fit the shape of the housing of the game device. There may be multiple measuring elements 111. A cover 14 may be placed on top of the pressure-sensitive unit 10. The control unit 12 calculates an analog value corresponding to the amount of user operation (for example, pressing a button on a game controller), or generates an ON signal or OFF signal corresponding to the amount of user operation.

[0067] As shown in FIG. 8 , the tactile sensor 1 includes a pair of pressure-sensitive units 10 , a measuring unit 11 , a control unit 12 , and a pair of covers 14 .

[0068] Covers 14 are disposed on both sides of the measurement unit 11. The covers 14 are disposed between the pressure-sensing unit 10 and the measurement unit 11.

[0069] The control unit 12 is disposed between the measurement unit 11 and the cover 14. The location of the control unit 12 is not limited to the example shown in FIG.

[0070] According to the fourth application example, the durability of the game device can be improved. In particular, according to the example of Fig. 8, the accuracy of detecting whether the user is gripping the game controller can be improved. This allows the user's gripping of the game controller to be included in the game instructions.

[0071] (4-3-5) Application Example 5 The following describes application example 5. Application example 5 is an example in which the tactile sensor 1 is placed on furniture (for example, a bed, a cushion, a chair, or flooring).

[0072] Specifically, the tactile sensor 1 is placed on furniture (for example, a bed mattress). In this case, the pressure-sensitive units 10 are molded to fit the shape of the furniture. There may be multiple measuring elements 111. When a user puts their weight on the furniture, the pressure-sensitive units 10 deform in response to the weight, and the tactile sensor 1 detects that the user has put their weight on the furniture.

[0073] In particular, if the control unit 12 is capable of connecting to the Internet, it may transmit the detection result (i.e., that the user has put their weight on the furniture) to a client device (e.g., a smartphone) connected to the Internet.

[0074] According to Application Example 5, it is possible to improve the accuracy of detecting when a user has put their weight on furniture. Furthermore, according to Application Example 5, since the tactile sensor 1 is placed inside the furniture, it is possible to improve the detection accuracy without impairing the aesthetic appearance of the furniture.

[0075] In particular, in use example 5, the control unit 12 transmits the detection results to the client device, so that the user of the client device can easily know whether the user of the furniture is safe or not, even if the user is away from the furniture user.

[0076] (4-3-6) Application Example 6 Application Example 6 will be described. Application Example 6 is an example in which the tactile sensor 1 is disposed on a pipe. FIG. 9 is a diagram showing an example of Application Example 6 of Modification Example 3.

[0077] Specifically, as shown in Fig. 9A, the tactile sensor 1 has an O-ring shape. As shown in Fig. 9B, the tactile sensor 1 is placed at the connection between pipes D1 and D2. At least one measuring element 111 is placed below the pressure-sensitive unit 10. Since the pressure-sensitive unit 10 deforms in response to pressure applied to the connection, the tactile sensor 1 measures the pressure applied to the connection between the pipes. The control unit 12 calculates an index value indicating the airtightness corresponding to the pressure as the amount of external force acting.

[0078] According to the application example 6, the state of the pipes D1 to D2 can be easily monitored.

[0079] (4-3-7) Application Example 7 The following describes application example 7. Application example 7 is an example in which the tactile sensor 1 is disposed on a lever for heavy machinery.

[0080] Specifically, the tactile sensor 1 is disposed on a heavy equipment lever for operating the heavy equipment. The heavy equipment is, for example, at least one of construction equipment and agricultural equipment. In this case, the pressure-sensing unit 10 is molded to fit the shape of the housing of the heavy equipment. There may be multiple measuring elements 111. A cover 14 may be disposed on top of the pressure-sensing unit 10. The control unit 12 calculates an analog value corresponding to the amount of user operation (e.g., gripping the heavy equipment lever), or generates an ON signal or OFF signal corresponding to the amount of user operation.

[0081] An example of the seventh application example is similar to that shown in FIG.

[0082] According to the seventh application example, the lever for heavy machinery can be made smaller.

[0083] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to the above-described embodiments. Furthermore, various improvements and modifications to the above-described embodiments are possible without departing from the spirit of the present invention. Furthermore, the above-described embodiments and Modification 1 can be combined.

[0084] 1: Tactile sensor 2: Display device 10: Pressure-sensitive section 10a: High-density area 10b: Low-density area 11: Measuring section 12: Control section 13: Power supply 14: Cover 101: Magnetic layer 111: Measuring element 112: Measuring circuit 1111: Coil 1112: Capacitor 1113: Magnet 1114: Hall element

Claims

1. A tactile sensor comprising a pressure-sensitive unit, the pressure-sensitive unit containing magnetically responsive particles, and a measuring unit that measures a response amount corresponding to a change in density distribution of the magnetically responsive particles caused by an external force applied to the pressure-sensitive unit.

2. The tactile sensor according to claim 1, wherein the measuring unit has a measuring element and a measuring circuit, the measuring element forms an LC parallel resonant circuit including a coil and a capacitor, and the measuring circuit measures, as the response quantity, the amount of change in inductance of the coil in response to pressure on the pressure-sensitive unit.

3. The tactile sensor according to claim 1, wherein the measurement unit has a measurement element and a measurement circuit, the measurement element being a magnet and a Hall element, and the measurement circuit measures the amount of change in the magnetic field of the Hall element as the response amount.

4. The tactile sensor according to any one of claims 1 to 3, wherein the magnetically responsive particles are in a foamed state.

5. A tactile sensor according to any one of claims 1 to 3, wherein the pressure-sensitive portion does not include a non-magnetic layer.

6. The tactile sensor according to any one of claims 1 to 3, further comprising a control unit that calculates a physical quantity based on the response quantity.

7. The tactile sensor according to claim 6, wherein the physical quantity is the amount of external force acting on the pressure-sensitive portion at each position.

8. The tactile sensor according to any one of claims 1 to 3, further comprising a cover portion disposed between the pressure-sensing portion and the measuring portion.

9. The tactile sensor according to any one of claims 1 to 3, wherein the pressure-sensitive section includes a high-density region and a low-density region.

10. A sensing system comprising a tactile sensor according to any one of claims 1 to 3, the tactile sensor being arranged on the seat surface and backrest of a vehicle seat, and measuring the body movements of an occupant in the seat.

11. The sensing system according to claim 10, further comprising an acceleration sensor that measures vibrations of the vehicle, and means for calculating the body movements, pulse, and heart rate of the occupant based on the body movements measured by the tactile sensor and the vibrations measured by the acceleration sensor.

12. A sensing system comprising a tactile sensor according to any one of claims 1 to 3, the tactile sensor being disposed on an end effector of a robot and measuring pressure generated when the robot grasps an object.

13. A sensing system comprising a tactile sensor according to any one of claims 1 to 3, wherein the tactile sensor is disposed in factory automation equipment and detects contact between the factory automation equipment and a target object.

14. A sensing system comprising a tactile sensor according to any one of claims 1 to 3, the tactile sensor being disposed in a game device and generating a signal in response to a user's operation.

15. A sensing system comprising a tactile sensor according to any one of claims 1 to 3, the tactile sensor being placed on furniture and detecting the weight of a user resting on the furniture.

16. A sensing system comprising a tactile sensor according to any one of claims 1 to 3, the tactile sensor being disposed at a pipe connection and measuring the pressure acting on the pipe connection.

17. A sensing system comprising a tactile sensor according to any one of claims 1 to 3, the tactile sensor being disposed on a lever for heavy machinery, and measuring the strength of the force with which a user grips the lever for heavy machinery.

Images