A tactile sensor, a robotic finger

Abstract

The utility model relates to a kind of tactile sensor, machine finger, including response deformation body, CDC, control module and force support component, response deformation body and force support component and enclose the inner cavity of sensor;Response deformation body top area is flexible body, and the bottom of flexible body is raised downward, wherein, flexible body is prepared to form upper electrode with conductive material and top surface is integrally coated outer insulating layer by the secondary forming process of conductive material and insulating material, or flexible body is made of insulating material and protruding surface is coated with conductive material to form upper electrode;Upper electrode is curved surface elastic electrode, and upper electrode has at least one lower electrode below, and the bottom surface of upper electrode and / or lower electrode top surface is provided with inner insulating layer;Protrusion and electrode are located in inner cavity, and response deformation body and / or force support component are provided with gas passage for communicating inner cavity with outside;CDC is respectively coupled each electrode, and control module is coupled with CDC.

Description

Technical Field

[0001] This utility model relates to robotic arms, and more particularly to a tactile sensor and a robotic finger. Background Technology

[0002] Tactile sensors have important applications in fields such as robotics, intelligent prosthetics, and human-computer interaction. Their core performance lies in the accurate perception of external forces.

[0003] Our prior patent CN209820667U proposes a high-sensitivity capacitive touch sensor solution. The sensor unit employs a flexible, multi-functional layer structure, with an upper curved elastic electrode and a lower electrode that are insulated from each other. Three-dimensional force sensing is achieved by utilizing the capacitance change caused by the deformation of the upper electrode. This design combines the advantages of high sensitivity, fast response speed, and simplified structure, making it particularly suitable for applications requiring three-dimensional force feedback.

[0004] In the above scheme, the multifunctional layer and the upper curved elastic electrode can be integrated into a deformable body. When converting this sensor into a structural product (such as a tactile bionic robotic finger), it was found that because the sensor needs to be placed inside the structural cavity and surrounded by a shell for mechanical protection, the flexible deformable body part that interacts with the outside world is exposed to sense force. At the same time, the deformable body surface is insulated. The necessary design of mechanical protection and insulation protection causes the deformable body's deformation resilience to decline.

[0005] (1) When the surface of the deformable body is insulated, the reliability of the bonding between the conductive material and the insulating material is insufficient. During the dynamic stress process, interface peeling or relative slippage is likely to occur, resulting in distortion of force transmission.

[0006] (2) The tactile sensor adopts a closed structure. When the flexible three-dimensional curved surface structure of the deformable body is deformed under pressure, the change in internal air pressure hinders its rapid deformation and subsequent rebound, and may even lead to hysteresis, reducing detection accuracy and dynamic response capability.

[0007] Therefore, it is urgent to design an assembly scheme for this flexible three-dimensional curved surface sensing structure, which should ensure a tight bond between the conductive layer and the insulating layer, while optimizing the air pressure regulation mechanism. The two should work together to achieve a balance between the deformation performance of the deformable body and the protective design. Utility Model Content

[0008] To address the shortcomings of existing technologies, this invention provides a tactile sensor.

[0009] The tactile sensor of this invention includes a deformable sensing element, a capacitance-to-digital conversion circuit, a control module, and a rigid force-bearing support component. The deformable sensing element and the force-bearing support component enclose the inner cavity of the sensor. The top region of the deformable sensing element is a flexible body with a downward-facing protrusion. The flexible body is made of conductive material to form an upper electrode, and its top surface is integrally covered with an outer insulating layer through a secondary molding process of conductive and insulating materials. Alternatively, the flexible body is made of insulating material, and the protruding surface is coated with conductive material to form the upper electrode. The upper electrode is a curved elastic electrode, and at least one lower electrode is located below the upper electrode. An inner insulating layer is provided on the bottom surface of the upper electrode and / or the top surface of the lower electrode. The projection of the upper electrode relative to the lower electrode at least partially covers each lower electrode. The flexible body deforms under user pressure, causing the upper electrode to change its indirect contact area with the lower electrode. The protrusion and electrode are located in the inner cavity. The deformable sensing element and / or the force-bearing support component are provided with a gas channel for connecting the inner cavity with the outside. The capacitance-to-digital conversion circuit is coupled to each electrode, and the control module is coupled to the capacitance-to-digital conversion circuit.

[0010] The tactile sensor of this utility model also includes the following auxiliary technical solutions:

[0011] This includes a circuit board located in the inner cavity, with lower electrodes arranged on the front side of the circuit board, and the circuit board body having at least one vent hole.

[0012] The vent is positioned far enough from the central axis of the protrusion to prevent the vent from becoming blocked due to deformation of the protrusion under pressure.

[0013] The circuit board has exposed electrode pads on the front side, and the upper electrode is pressed onto the electrode pads by a flexible conductive buffer.

[0014] The system includes a first circuit board and a second circuit board, which are stacked and fixed to each other. They are connected by pads on their contact surfaces, and the lower electrode is arranged on the front side of the upper circuit board.

[0015] The capacitor-to-digital converter circuit and control module are located on the back of the circuit board.

[0016] The circuit board has exposed pads for external transmission; or the circuit board is connected to a connection terminal for external transmission via wires, and a winding post is provided in the inner cavity, with the wires at least partially wound around the winding post.

[0017] Wherein, the flexible body is silicone; and / or, the gas channel is a venting groove located at least partially on the inductive deformable body.

[0018] The flexible body has contact protrusions with its top facing upwards; and / or, the lower electrode has at least three, each of which is uniformly surrounded along the central axis of the protrusion.

[0019] A robotic finger is also provided, including the aforementioned tactile sensor.

[0020] The tactile sensor proposed in this invention ensures the stability of force transmission through a combination of conductive and insulating materials. At the same time, a gas channel is set in the inner cavity of the sensor to balance the internal and external air pressure, enabling the flexible body to rebound quickly after being compressed. This ensures product reliability while improving the deformation and resilience of the flexible body, thereby enhancing the sensor's sensitivity, durability, and dynamic response performance. Attached Figure Description

[0021] Figure 1 An exploded view of the overall tactile sensor is shown.

[0022] Figure 2a This diagram illustrates a structure in which conductive silicone is coated with insulating silicone through a secondary molding process. Figure 2b A schematic diagram of a structure for spraying conductive ink onto an insulating silicone surface is shown.

[0023] Figure 3 A structural diagram of a double-layer circuit board is shown.

[0024] Figure 4 A schematic diagram of the structure of the inductive deformable body forming the ventilation groove is shown.

[0025] Figure 5 A schematic diagram of the circuit board body with added vent holes is shown.

[0026] Figure 6a This diagram illustrates the structure of the circuit board's external force pads using springs / probes to transmit force externally. Figure 6b A schematic diagram of the structure for fixing the lead wire at the winding post is shown. Detailed Implementation

[0027] 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.

[0028] In addition to being used in mechanical fingers to achieve robotic touch, the tactile sensor of this invention can also be applied to products or systems such as touch switches, gripping rehabilitation training equipment, and wearable health monitoring devices to achieve functions such as force sensing or human-computer interaction.

[0029] The following explanation uses the application of a robotic finger as an example. As one exemplary implementation, see... Figure 1 The tactile sensor consists of three parts: a sensing deformable element 100, a circuit board 200, and a rigid force-bearing support component 300. The force-bearing support component 300 serves as the back cover of the product, and together with the sensing deformable element 100, it encloses the inner cavity space of the sensor. Electronic components such as the circuit board 200 are placed in the inner cavity to form mechanical protection.

[0030] The top region of the inductive deformable body 100 is a flexible body 110. The top of the flexible body 110 faces upwards, forming contact protrusions to increase force sensitivity, while the bottom faces downwards, forming protrusions. The protrusions are preferably designed to gradually taper downwards, and are preferably hemispherical or semi-ellipsoidal in shape, providing superior deformation linearity. As an optional embodiment of the flexible body 110, see... Figure 2a The flexible body 110 is made of conductive material, with protrusions forming the upper electrode 400 on an elastic curved surface. The conductive material is preferably conductive silicone, which has a low elastic modulus, easily deforms under stress, and quickly returns to its original shape after being released. The outer insulating layer 130 is made of insulating silicone, integrally coated onto the top surface of the conductive silicone through a secondary molding process. During manufacturing, the conductive silicone portion is first formed by pressure molding or liquid silicone injection molding, followed by the insulating silicone portion, ultimately achieving an integrated combination of the upper electrode 400 and the outer insulating layer 130. Alternatively, as another optional embodiment of the flexible body 110, see [link to relevant documentation]. Figure 2b The flexible body 110 is directly shaped using insulating silicone, and the raised surface is coated with conductive ink 140 to form the upper electrode 400. This also avoids slippage caused by poor bonding between silicone particles, ensuring force transmission performance.

[0031] See Figure 3 The circuit board 200 has a lower electrode 500 arranged on its front side, located below the upper electrode 400. A single lower electrode 500 enables one-dimensional (normal) force measurement, while at least three electrodes evenly arranged around the central axis of the protrusion enable three-dimensional force detection. An inner insulating layer is provided on the bottom surface of the upper electrode 400 and / or the top surface of the lower electrode 500. The projection of the upper electrode 400 relative to the lower electrode 500 at least partially covers each lower electrode 500. The flexible body 110 deforms under user pressure, causing the upper electrode 400 to change its indirect contact area with the lower electrode 500. The circuit board 200 has a capacitor-to-digital converter (CDC) circuit and a control module on its back side. The CDC circuit couples to each electrode and is directly connected via PCB traces to reduce parasitic capacitance. The control module is coupled to the capacitor-to-digital converter circuit.

[0032] See Figure 4 The protrusions and electrodes are located in the inner cavity. The inductive deformable body 100 and / or the force-bearing support member 300 are provided with a gas channel 121 to connect the inner cavity with the outside. The gas channel 121 balances the internal and external air pressure, so that the flexible body 110 can quickly rebound after being compressed.

[0033] This invention achieves synergistic optimization in the deformation performance of the flexible body 110 through the combination design of conductive and insulating materials and the pressure balance design of the gas channel 121. The combination design of conductive and insulating materials avoids signal distortion caused by material peeling or slippage under stress, giving the flexible body 110 higher mechanical durability. The gas channel 121 reduces the internal resistance of the flexible body 110 during deformation by balancing the internal and external air pressure, making the deformation fit the external force and avoiding uneven local deformation or hysteresis effect caused by air pressure difference. At the same time, it eliminates the negative pressure adsorption phenomenon when the flexible body 110 rebounds. The two work together to improve the deformation and rebound performance of the flexible body 110, ensuring the detection accuracy and dynamic response capability of the sensor.

[0034] Further, see Figure 4 The gas channel 121 is a ventilation groove located at least partially on the inductive deformable body 100. The pressurized upper cavity quickly discharges air to avoid high pressure hindering deformation. After the pressure is released, air is quickly drawn in to eliminate the negative pressure adsorption effect, making the flexible body 110 rebound more quickly and enhancing dynamic response.

[0035] See Figure 5 As an improvement, the circuit board 200 body has at least one vent hole 210. The vent hole 210 is located at a position far enough from the central axis of the protrusion to avoid the vent hole being blocked due to the deformation of the protrusion under pressure. The design of the vent hole 210 can reduce the difficulty of manufacturing structural components, while ensuring the air flow between the upper and lower cavities and reducing the rebound time.

[0036] See Figure 3 The circuit board 200 has exposed electrode pads on its front side, and the upper electrode 400 is pressed onto the electrode pads by a flexible conductive buffer. The flexible conductive buffer is preferably conductive foam 220. The PCB electrode pads are exposed, and the conductive foam 220 is pressed into contact with the flexible body 110. The conductive foam 220 has a certain amount of deformation, which can ensure contact and reduce the impact of processing errors.

[0037] Furthermore, the circuit board 200 has two parts, including a first circuit board 230 and a second circuit board 240. The first circuit board 230 and the second circuit board 240 are stacked and fixed to each other. They are connected by solder pads on the contact surface. The lower electrode 500 is arranged on the front side of the upper circuit board 240. For irregular curved surfaces, the risk of breakage due to excessively thin and long induction bumps is avoided by welding the double-layer board.

[0038] See Figure 6a The circuit board 200 has exposed solder pads 250 for external transmission. External transmission is achieved using spring clips / probes, making module disassembly easier and eliminating the need for wire disconnection; alternatively, the circuit board 200 can be connected to connection terminals for external transmission via wires, see [link to relevant documentation]. Figure 6bThe inner cavity is equipped with a winding post 260. At least part of the wire is wrapped around the winding post and glued to fix it, so as to fix the wire and prevent it from bending and breaking.

[0039] 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: It includes a sensing deformation body, a capacitance-to-digital conversion circuit, a control module, and a rigid force-bearing support component. The sensing deformation body and the force-bearing support component enclose the inner cavity of the sensor. The top region of the inductive deformable body is a flexible body with the bottom of the flexible body protruding downwards. The flexible body is made of conductive material to form the upper electrode and the top surface is integrally covered with an outer insulating layer by a secondary molding process of conductive material and insulating material. Alternatively, the flexible body is made of insulating material and the protruding surface is coated with conductive material to form the upper electrode. The upper electrode is a curved elastic electrode, and there is at least one lower electrode below the upper electrode. An inner insulating layer is provided on the bottom surface of the upper electrode and / or the top surface of the lower electrode. The projection of the upper electrode relative to the lower electrode at least partially covers each lower electrode. The flexible body is deformed by the user's pressure, which causes the upper electrode to change the indirect contact area with the lower electrode. The protrusion and electrode are located in the inner cavity, and the inductive deformation body and / or force-supporting component are provided with a gas channel for connecting the inner cavity with the outside. The capacitor-to-digital converter circuit is coupled to each electrode, and the control module is coupled to the capacitor-to-digital converter circuit.

2. The tactile sensor according to claim 1, characterized in that: It includes a circuit board located in the inner cavity, with the lower electrode arranged on the front of the circuit board, and the circuit board body has at least one vent hole.

3. The tactile sensor according to claim 2, characterized in that: The vent is positioned far enough from the central axis of the protrusion to prevent the vent from becoming blocked due to deformation of the protrusion under pressure.

4. The tactile sensor according to claim 2, characterized in that: The circuit board has exposed electrode pads on the front side, and the upper electrode is pressed onto the electrode pads by a flexible conductive buffer.

5. The tactile sensor according to claim 2, characterized in that: It includes a first circuit board and a second circuit board, which are stacked and fixed to each other. They are connected by pads on the contact surfaces, and the lower electrode is arranged on the front side of the upper circuit board.

6. The tactile sensor according to claim 2, characterized in that: The capacitor-to-digital converter circuit and control module are located on the back of the circuit board.

7. The tactile sensor according to claim 2, characterized in that: The circuit board has exposed pads for external transmission; or The circuit board is connected to a connection terminal for external transmission via wires. A winding post is provided in the inner cavity, and the wires are at least partially wound around the winding post.

8. The tactile sensor according to claim 1, characterized in that: The flexible body is made of silicone. And / or, the gas passage is a venting groove located at least partially on the inductive deformable body.

9. The tactile sensor according to claim 1, characterized in that: The flexible body forms contact protrusions with its top facing upwards; And / or, the lower electrode has at least three, each lower electrode being uniformly surrounded along the central axis of the protrusion.

10. A robotic finger, characterized in that: Including the tactile sensor as described in any one of claims 1-9.

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