Tactile sensor, electronic skin and robot

Abstract

The utility model relates to a touch sensor, an electronic skin and a robot. The touch sensor comprises a capacitance digital conversion circuit, a digital processing circuit and a sensing unit, each sensing unit comprises at least one flexible electrode, at least one protrusion is formed on the side, facing the first direction, of each flexible electrode, the outer surface of each protrusion is an elastic curved surface, each protrusion corresponds to at least one detection electrode, and the projection, facing the first direction, of each protrusion at least covers part of the area of the corresponding detection electrode. The flexible electrode and the detection electrode form a capacitance device for detecting pressure; a flexible insulating material is arranged between the bulge and the corresponding detection electrode as a filler of at least part of the gap to form mutual nesting of the bulge and the corresponding detection electrode, and the detection electrode is insulated from the flexible electrode; the capacitance-to-digital conversion circuit is respectively coupled with each detection electrode; and the digital processing circuit is used for logic processing and / or logic sequence control and is coupled with the capacitance digital conversion circuit.

Description

Technical Field

[0001] This utility model relates to the field of robotic tactile sensing, and more particularly to a tactile sensor, electronic skin, and robot. Background Technology

[0002] CN111896165A discloses a touch sensor structure in which the upper electrode protrudes downward to form a hemispherical elastic electrode, and the lower electrode measures one-dimensional normal force when there is one electrode and three-dimensional force when there are four electrodes. The CDC inputs excitation to the upper electrode and receives it from the lower electrode. The sensor achieves high-sensitivity mechanical sensing mainly by pressing the hemispherical protrusion on the lower electrode to form an order of magnitude change in the indirect contact area (with an insulating layer in between) from point to surface. However, the protrusion is not fixed to the lower electrode. After pressing, the elastic recovery of the protrusion may result in the center not returning to the correct position, causing a deviation between the center point of the protrusion and the geometric center of the lower electrode, which affects the detection reference. Utility Model Content

[0003] This invention addresses the shortcomings of existing technologies by providing a tactile sensor, electronic skin, and robot.

[0004] A tactile sensor is provided, comprising a capacitance-to-digital conversion circuit, a digital processing circuit, and a sensing unit. The sensing unit includes at least one flexible electrode, with at least one protrusion formed on the side of the flexible electrode facing a first direction. The outer surface of the protrusion is an elastic curved surface. Each protrusion corresponds to at least one detection electrode. The projection of the protrusion facing the first direction at least covers a portion of the area of ​​each corresponding detection electrode. The flexible electrode and the detection electrode form a capacitive device for detecting pressure. A flexible insulating material is provided between the protrusion and the corresponding detection electrode as a filler for at least part of the gaps, forming a nested arrangement between the protrusion and the corresponding detection electrode. The detection electrode is insulated from the flexible electrode. The indirect contact area of ​​the protrusion on each corresponding detection electrode is affected by the deformation of the flexible electrode under external force. The capacitance-to-digital conversion circuit is coupled to each detection electrode. The digital processing circuit, used for logic processing and / or logic sequence control, is coupled to the capacitance-to-digital conversion circuit.

[0005] Compared with the prior art, the structure of this utility model uses flexible insulating material to fill the protrusion and the detection electrode respectively, which can overcome the return center offset of the protrusion elastic recovery and improve the sensor range.

[0006] The tactile sensor of this utility model also includes the following auxiliary solutions:

[0007] Among them, the Shore hardness of flexible insulating materials is lower than that of flexible electrodes.

[0008] This includes a circuit board, with detection electrodes formed on the surface of the circuit board; the circuit board, flexible insulating material, and flexible electrodes are stacked or nested.

[0009] The circuit board is an FPC.

[0010] The circuit board has a first wear-resistant insulating layer on the side facing the first direction, and the first wear-resistant insulating layer is thick enough to isolate or reduce electric field penetration; and / or, the circuit board has an active shielding layer on the side facing the first direction.

[0011] A second wear-resistant insulating layer is provided on the side of the flexible electrode away from the first direction.

[0012] In this circuit board, at least one third electrode is provided on the side facing the first direction. The third electrode serves as an electrode for detecting the approach of an object and is coupled to the capacitor-to-digital converter circuit.

[0013] This includes a switch array, where the capacitor-to-digital converter circuit is coupled to each flexible electrode through the switch array, and the switch array serves as a time-division multiplexing channel for the flexible electrodes coupled to the capacitor-to-digital converter circuit or ground.

[0014] The flexible electrode has at least two, and each flexible electrode forms a mutual capacitance for detecting the approach of an object; and / or, the flexible electrode has at least one, and the flexible electrode forms a self-capacitance for detecting the approach of an object.

[0015] Each protrusion is provided with one or more detection electrodes as self-capacitance electrodes.

[0016] Each protrusion is provided with at least two detection electrodes, and the detection electrodes corresponding to each protrusion form a planar mutual capacitance.

[0017] Each protrusion is provided with a first detection electrode and a second detection electrode; the protrusion has multiple forming dot arrays, the first detection electrodes in the same row of the dot array are coupled to each other, and the second detection electrodes in the same column of the dot array are coupled to each other; the digital processing circuit controls the capacitor digital conversion circuit to obtain the planar mutual capacitance between the first detection electrode and the second detection electrode at each point according to the row and column scanning method.

[0018] The outer surface of the protrusion forms a spherical curved surface; the first detection electrode and the second detection electrode rotate outward in a plane around the corresponding protrusion center to form an equidistant spiral.

[0019] Each protrusion is provided with one or more detection electrodes, and the flexible electrode serves as a common electrode. The common electrode and each detection electrode form a mutual capacitance.

[0020] The detection electrode and the flexible electrode are insulated by a filler.

[0021] The detection electrode surface is covered with an insulating layer made of wear-resistant material, and the detection electrode and the flexible electrode are insulated from each other through the insulating layer.

[0022] The insulation layer may be up to 2 millimeters thick, or up to 100 micrometers thick.

[0023] The flatness of the insulating layer is configured to be between 0 and 5 micrometers.

[0024] An electronic skin is also provided, including the aforementioned tactile sensor.

[0025] A robot is also provided, including the aforementioned tactile sensor. Attached Figure Description

[0026] Figure 1 An exemplary structure of a tactile sensor is given;

[0027] Figure 2 A schematic diagram of the internal cross-section of the tactile sensor is provided.

[0028] Figure 3 A schematic diagram of a planar mutual capacitance is given, showing the arrangement of double-helix electrodes corresponding to the protrusions.

[0029] Figure 4 A schematic diagram of a structure is given showing multiple detection electrodes arranged to form mutual capacitance between parallel plates corresponding to the protrusions; and

[0030] Figure 5 An exemplary structure of a tactile sensor with its structure reversed is given. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0032] Example 1

[0033] Figure 1 An exemplary structure of a tactile sensor is provided, including a sensing unit and a circuit board 100. A capacitance-to-digital converter (CDC) circuit and a digital processing circuit are disposed on the circuit board 100 and are coupled to each other. The digital processing circuit can be controlled by a processor for logic processing through software control, or by a state controller for logical sequence control through hardware logic control.

[0034] The sensing unit includes at least one flexible electrode 200, and at least one protrusion 201 is formed on the side of the flexible electrode 200 facing the first direction, which can be as follows: Figure 1 As shown, it can be set upwards, or as... Figure 5 As shown, facing downwards. See also... Figure 2The outer surface of the protrusion 201 is an elastic curved surface. Each protrusion 201 corresponds to at least one detection electrode 300. The projection of the protrusion 201 toward the first direction covers at least a portion of the area of ​​each corresponding detection electrode 300. The flexible electrode 200 and the detection electrode 300 form a capacitive device for detecting pressure.

[0035] A flexible insulating material 400 is provided between the protrusion 201 and the corresponding detection electrode 300 as a filler for at least part of the gap, forming a nested structure between the protrusion 201 and the corresponding detection electrode 300. The detection electrode 300 is insulated from the flexible electrode 200. In one alternative, the detection electrode 300 and the flexible electrode 200 are insulated by the filler. In another alternative, and more preferably, the surface of the detection electrode 300 is covered with an insulating layer 301 made of a wear-resistant material. The insulating layer 301 is formed into an insulating film by spraying, and the surface flatness is controllable. The insulating film serves as a wear-resistant protection for the detection electrode 300, and the flatness can be easily achieved to between 0-5 micrometers through the process, ensuring the consistency of deformation among the protrusions. Furthermore, the thickness of the insulating layer 301 affects the sensor's sensitivity to pressure detection. In applications such as electronic skin placed on the sole of a mechanical foot to detect the distribution of foot pressure, the force varies greatly, and the thickness of the insulating layer 301 is at most 2 mm to meet the basic detection sensitivity requirements. In other applications, such as electronic skin placed on the fingertips of robots, in order to enable the sensor's force measurement resolution to reach a level far exceeding that of human fingertips, the thickness of the insulating layer 301 is set to be less than 100 micrometers.

[0036] The indirect contact area of ​​the protrusions 201 on each corresponding detection electrode 300 caused by the deformation of the flexible electrode 200 under external force; the capacitor-to-digital converter circuit is coupled to each detection electrode 300; the digital processing circuit, used for logic processing and / or logic sequence control, is coupled to the capacitor-to-digital converter circuit. By using flexible insulating material to fill and connect the protrusions 201 and the detection electrodes 300 respectively, the center offset of the protrusion's elastic recovery is overcome. In the case of no filling in the middle, to ensure the measurement range, the protrusion needs to be doped to make it slightly harder, obtaining the measurement range by sacrificing its resilience. When there is filling in the middle, the protrusion does not need to be doped and can maintain good elasticity. The combination of the protrusion and the filling achieves a higher measurement range.

[0037] The Shore hardness of the flexible insulating material 400 is less than that of the flexible electrode 200. The flexible electrode 200 is made of conductive silicone, and the flexible insulating material 400 is made of insulating ultra-flexible silicone. This ensures that the protrusion is easily deformed under stress, thus guaranteeing the sensitivity of the sensor.

[0038] The detection electrode 300 is formed on the surface of the circuit board 100 and is easily manufactured by PCB copper cladding process. At this time, the circuit board 100, flexible insulating material 400 and flexible electrode 200 can be stacked or nested, and the tactile sensor forms a thin skin, which is more in line with the image of skin. The circuit board 100 is preferably an FPC to form a flexible electronic skin (the detection electrodes are small and densely distributed).

[0039] As an improvement, a first wear-resistant insulating layer 101 is provided on the side of the circuit board 100 facing the first direction. The wear-resistant insulating layer provides isolation and protection. The first wear-resistant insulating layer is thick enough to isolate or reduce electric field penetration and reduce interference from the robot's own metal on the capacitive detection. And / or, an active shielding layer is provided on the side of the circuit board 100 facing the first direction to shield the robot's own metal from interference with the electrodes. Furthermore, a second wear-resistant insulating layer 202 is provided on the side of the flexible electrode 200 away from the first direction as protection for the outer skin.

[0040] As another improvement, a switch array is included. The capacitance-to-digital converter (CDC) circuit couples each flexible electrode 200 through the switch array, which serves as a time-division multiplexing channel for coupling the flexible electrodes 200 to the CDC circuit or ground. When force measurement is required, the flexible electrodes 200 are coupled to ground through the switch array, with the flexible electrodes 200 themselves acting as shielding electrodes to ensure accurate force measurement. When force measurement is not required, the switch array couples the flexible electrodes 200 to the DC-DC converter, with the flexible electrodes 200 acting as proximity sensing electrodes to detect object approach. Specifically, there are at least two flexible electrodes 200, with each pair of flexible electrodes 200 forming mutual capacitance for detecting object approach; and / or, there is at least one flexible electrode 200, which forms a self-capacitance for detecting object approach.

[0041] Furthermore, as a first embodiment, each protrusion 201 is provided with one or more detection electrodes 300 as self-capacitance electrodes. During measurement, the digital processing circuit outputs excitation to each upper electrode and uses itself as the receiver.

[0042] Alternatively, as a second implementation scheme, considering that self-capacitance is a type of capacitance to ground, and the distance between the foot and the ground is too close, the influence of the ground on self-capacitance is very large. To improve the sensitivity and signal-to-noise ratio of pressure detection, see [reference needed]. Figure 3Each protrusion 201 is provided with at least two detection electrodes 310 and 320, and the detection electrodes 310 and 320 corresponding to each protrusion 201 form a planar mutual capacitance. The planar mutual capacitance overcomes detection interference caused by large areas of metal on the surface of the robotic arm or excessive proximity to the ground, and establishes a decreasing trend in mutual capacitance with pressure. Specifically, each protrusion 201 is provided with a first detection electrode 310 and a second detection electrode 320; the protrusion 201 has multiple dot arrays, with the first detection electrodes 310 in the same row of the dot array coupled to each other, and the second detection electrodes 320 in the same column of the dot array coupled to each other; the digital processing circuit controls the capacitor-to-digital conversion circuit to obtain the planar mutual capacitance between the first detection electrodes 310 and the second detection electrodes 320 at each point according to the row and column scanning method. By scanning the mutual capacitance in the rows and columns, a high-density multi-point force measurement is formed using a small number of channels. Most preferably, the outer surface of the protrusion forms a spherical curved surface; the first detection electrode 310 and the second detection electrode 320 rotate outwards in a plane around the center of the corresponding protrusion 201 to form an equidistant spiral. The spiral involute curve gradually expands outwards in a circular shape, and the corresponding convex surface is a spherical curved surface. When pressed, the indirect contact area of ​​the convex surface on the detection electrode gradually expands, which conforms to the gradual expansion of the gap between the first detection electrode 310 and the second detection electrode 320. The consistency between the two changes is good, and the regularity of force and capacitance changes is strong, which can effectively improve the resolution of force changes.

[0043] Alternatively, as a third implementation plan, see Figure 4 Each protrusion 201 is provided with one or more detection electrodes 300, and the flexible electrode 200 serves as a common electrode. The common electrode and each detection electrode 300 form mutual capacitance.

[0044] Example 2

[0045] Example 2 uses the same technology as Example 1, except that the flexible electrode and the detection electrode are reversed, that is, the first direction is downward. See [link to example]. Figure 5 At this time, the circuit board is located below. At least one third electrode 500 is additionally set on the bottom surface of the circuit board. The third electrode 500 serves as an electrode for detecting the approach of an object and is coupled to the capacitor-to-digital converter circuit.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit the scope of protection of this utility model. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the essence and scope of the technical solutions of this utility model.

Claims

1. A tactile sensor, characterized in that: Includes a capacitor-to-digital converter circuit, a digital processing circuit, and a sensing unit; The sensing unit includes at least one flexible electrode, and at least one protrusion is formed on the side of the flexible electrode facing the first direction. The outer surface of the protrusion is an elastic curved surface. Each protrusion corresponds to at least one detection electrode. The projection of the protrusion facing the first direction covers at least a portion of the area of ​​each corresponding detection electrode. The flexible electrode and the detection electrode form a capacitive device for detecting pressure. A flexible insulating material is provided between the protrusion and the corresponding detection electrode as a filler for at least part of the gap, forming a nested structure between the protrusion and the corresponding detection electrode. The detection electrode is insulated from the flexible electrode. The protrusion involved in the deformation of the flexible electrode by external force has an indirect contact area on each corresponding detection electrode. Each detection electrode is coupled to a capacitor-to-digital converter circuit. Digital processing circuits used for logic processing and / or logic sequence control, coupled capacitor-to-digital converter circuits.

2. The tactile sensor according to claim 1, characterized in that: The Shore hardness of flexible insulating materials is less than that of flexible electrodes.

3. The tactile sensor according to claim 1, characterized in that: Includes a circuit board, with detection electrodes formed on the surface of the circuit board; Circuit boards, flexible insulating materials, and flexible electrodes are stacked or nested.

4. The tactile sensor according to claim 3, characterized in that: The circuit board is an FPC.

5. The tactile sensor according to claim 3, characterized in that: A first wear-resistant insulating layer is provided on the side of the circuit board facing the first direction, and the first wear-resistant insulating layer is thick enough to isolate or reduce electric field penetration. And / or, an active shielding layer is provided on the side of the circuit board facing the first direction.

6. The tactile sensor according to claim 5, characterized in that: A second wear-resistant insulating layer is provided on the side of the flexible electrode away from the first direction.

7. The tactile sensor according to claim 3, characterized in that: At least one third electrode is provided on the side of the circuit board facing the first direction. The third electrode serves as an electrode for detecting the approach of an object and is coupled to a capacitor-to-digital converter circuit.

8. The tactile sensor according to claim 1, characterized in that: It includes a switch array, in which the capacitor-to-digital converter circuit is coupled to each flexible electrode through the switch array, and the switch array serves as a time-division multiplexing channel for the flexible electrode to be coupled to the capacitor-to-digital converter circuit or ground.

9. The tactile sensor according to claim 8, characterized in that: The flexible electrode has at least two, and each flexible electrode forms a pair of mutual capacitances for detecting the proximity of objects. And / or, the flexible electrode has at least one, and the flexible electrode forms a self-capacitance for detecting the approach of an object.

10. The tactile sensor according to claim 8, characterized in that: Each protrusion is provided with one or more detection electrodes as self-capacitance electrodes.

11. The tactile sensor according to claim 8, characterized in that: Each protrusion is provided with at least two detection electrodes, and the detection electrodes corresponding to each protrusion form a planar mutual capacitance.

12. The tactile sensor according to claim 11, characterized in that: Each protrusion is equipped with a first detection electrode and a second detection electrode; The protrusion has multiple forming lattices, in which the first detection electrodes in the same row are coupled to each other, and the second detection electrodes in the same column are coupled to each other. The digital processing circuit controls the capacitor digital conversion circuit to obtain the planar mutual capacitance between the first detection electrode and the second detection electrode at each point according to the row and column scanning method.

13. The tactile sensor according to claim 12, characterized in that: The raised outer surface forms a spherical curved surface; The first and second detection electrodes rotate outwards in a plane around the corresponding protrusion center to form an equidistant spiral.

14. The tactile sensor according to claim 8, characterized in that: Each protrusion is provided with one or more detection electrodes, and the flexible electrode serves as a common electrode. The common electrode and each detection electrode form a mutual capacitance.

15. The tactile sensor according to claim 1, characterized in that: The detection electrode and the flexible electrode are insulated by a filler.

16. The tactile sensor according to claim 1, characterized in that: The surface of the detection electrode is covered with an insulating layer made of wear-resistant material, and the detection electrode and the flexible electrode are insulated from each other through the insulating layer.

17. The tactile sensor according to claim 16, characterized in that: The insulation layer is at most 2 millimeters thick, or at most 100 micrometers thick.

18. The tactile sensor according to claim 16, characterized in that: The flatness of the insulating layer is configured to be between 0 and 5 micrometers.

19. An electronic skin, characterized in that, Including the tactile sensor as described in any one of claims 1-18.

20. A robot, characterized in that, Including the tactile sensor as described in any one of claims 1-18.

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