A haptic sensor assembly structure, a robot finger

Abstract

The utility model relates to a kind of tactile sensor assembly structure, machine finger, including response deformation body, CDC, control module and hard stress support component;Response deformation body includes flexible body and hard skeleton, skeleton as insert, flexible body is formed by heat pressing or injection molding and is wrapped in the insert top to form soft and hard integration, the cavity of response deformation body is enclosed by both;Flexible body bottom is raised to form suspension type upper electrode towards cavity, upper electrode is curved surface elastic electrode, and upper electrode has at least one lower electrode below, upper electrode and lower electrode are insulated, flexible body is pressed by user and is deformed to drive upper electrode to change indirect contact area to lower electrode;Stress support component is rigidly combined as the substrate of sensor and skeleton, and protrusion and electrode are located in the enclosed space formed by stress support component, skeleton and flexible body;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 assembly structure and a robotic finger. Background Technology

[0002] As a key sensing component in fields such as robotics, intelligent prosthetics, wearable devices, and human-computer interaction, tactile sensors are fundamentally about the accurate detection of external pressure or contact force.

[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), there are assembly process challenges:

[0005] (1) Structural compatibility issues: The deformable body is a flexible three-dimensional curved surface structure, while the product shell is mostly a rigid component. The difference in mechanical properties between the two leads to sensitivity to assembly tolerance. If the assembly is too loose, it will easily lead to displacement deviation; if it is too tight, it will cause pre-tension stress, both of which will reduce product consistency.

[0006] (2) Performance reliability risk: Uneven assembly stress can easily cause fatigue damage to deformable parts, which will affect the durability of the sensor in the long term.

[0007] This problem has hindered the industrialization of this patented technology in high-precision application scenarios, and there is an urgent need to design an assembly scheme that takes into account product reliability for this flexible three-dimensional curved surface sensing structure. Utility Model Content

[0008] To address the shortcomings of existing technologies, this utility model provides a tactile sensor assembly structure.

[0009] The tactile sensor assembly structure of this utility model includes a deformable sensing body, a capacitance-to-digital conversion circuit, a control module, and a rigid force-bearing support component. The deformable sensing body includes a flexible body and a rigid skeleton. The skeleton serves as an insert in the insert molding process. The flexible body is wrapped around the top of the insert by hot pressing or injection molding to form a soft-hard integrated structure. The two together enclose the cavity of the deformable sensing body, and the skeleton serves as the structural support for the flexible body. The bottom of the flexible body protrudes towards the cavity to form a suspended upper electrode. The upper electrode is a curved elastic electrode. Below the upper electrode is at least one lower electrode. The bottom surface of the upper electrode and / or the top surface of the lower electrode are provided with an inner insulating layer. 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 the indirect contact area with the lower electrode. The force-bearing support component serves as the base of the sensor and is rigidly combined with the skeleton. The protrusion and the electrode are located in the enclosed space formed by the force-bearing support component, the skeleton, and the flexible body. 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 assembly structure of this utility model also includes the following auxiliary technical solutions:

[0011] This includes a circuit board located within an enclosed space, with the lower electrode arranged on the front side of the circuit board.

[0012] The circuit board is a PCB board, and the load-bearing support components, the PCB board and the frame are stacked in sequence and locked together by threaded fasteners through the first direction.

[0013] The frame or load-bearing support component has a transverse sliding groove, the front end of the PCB board is inserted into the sliding groove, and the rear end is locked by threaded fasteners.

[0014] The rear end of the load-bearing support member extends upward to be flush with the inductive deformation body, and the rear end of the skeleton is locked to the rear end of the load-bearing support member along the second direction by threaded fasteners, with the first direction and the second direction intersecting.

[0015] 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.

[0016] The capacitor-to-digital converter circuit and control module are located on the back of the circuit board.

[0017] In one case, 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 through a secondary molding process of conductive material and insulating material; or, the flexible body is made of insulating material and the raised surface is coated with conductive material to form the upper electrode.

[0018] The flexible body is made of silicone; and / or the skeleton is made of metal.

[0019] The upper electrode is a downward-convex hemispherical or semi-ellipsoidal structure; and / or, the lower electrode has at least three, each lower electrode being uniformly surrounded along the central axis of the convexity.

[0020] A robotic finger is also provided, comprising the aforementioned tactile sensor assembly structure.

[0021] This invention uses a two-stage structure of soft-hard transition and rigid anchoring to transfer the assembly stress of the flexible three-dimensional curved surface deformable body to the rigid base. The suspended internal precision sensor works in an environment free from stress interference, ensuring the consistency and reliability of product performance. Attached Figure Description

[0022] Figure 1 An exploded view of the overall tactile sensor assembly structure is shown.

[0023] 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.

[0024] Figure 3 A structural diagram of the circuit board is shown.

[0025] Figure 4 A schematic diagram of a sandwich composite rigid body is shown, illustrating the structure formed by screws passing through and locking together.

[0026] Figure 5 A schematic diagram of the structure showing the inductive deformable body and the PCB slide groove being fixedly locked by threads is shown.

[0027] Figure 6 A schematic diagram of the structure for locking screws in the cross direction is shown. Detailed Implementation

[0028] 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.

[0029] In addition to being used in mechanical fingers to realize robotic touch, the tactile sensor assembly structure of this utility model can also be applied to products or systems such as touch switches, grasping rehabilitation training equipment, and wearable health monitoring equipment to realize functions such as force sensing or human-computer interaction.

[0030] The following explanation uses the application of a robotic finger as an example. As one exemplary implementation, see... Figure 1 The tactile sensor assembly structure consists of three parts: a sensing deformable body 100, a circuit board 200, and a rigid force-bearing support component 300.

[0031] The inductive deformable body 100 includes a flexible body 110 and a rigid skeleton 120. The skeleton 120 serves as an insert in the insert molding process. Due to volume constraints, it is preferably made of metal to withstand high pressure and high temperature. The flexible body 110 is wrapped around the top of the insert by hot pressing or injection molding to form a rigid-soft integrated structure. Together, they enclose the cavity of the inductive deformable body 100. The skeleton 120 serves as the structural support for the flexible body 110. The top of the flexible body 110 forms contact protrusions facing upwards to increase stress sensitivity, and the bottom protrudes towards the cavity, preferably in a hemispherical or semi-ellipsoidal shape, providing superior deformation linearity. As an alternative embodiment of the flexible body 110, see... Figure 2a The flexible body 110 is made of a conductive material, with protrusions forming a suspended, elastic curved surface upper electrode 400. 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 and is integrally coated onto the top surface of the conductive silicone through a secondary molding process. Alternatively, as another optional embodiment of the flexible body 110, see [see...]. Figure 2b The flexible body 110 is directly shaped using insulating silicone, and conductive ink is applied to the raised surface by spraying to form the suspended elastic curved surface upper electrode 400.

[0032] 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 is coupled to each electrode and the control module. The CDC, control module, and electrodes are integrated on the same circuit board 200 to reduce parasitic capacitance.

[0033] See Figure 1 The force-bearing support component 300 serves as the base of the sensor, i.e. the back cover of the product, and is rigidly connected to the frame 120. The protrusions and electrodes are located in the enclosed space formed by the force-bearing support component 300, the frame 120 and the flexible body 110 to achieve mechanical protection.

[0034] This invention bypasses the challenges of assembling the flexible body 110 by redesigning the sensor's structure to address reliability issues. During manufacturing, the skeleton is CNC-machined / mold-made. The flexible body 110 (soft) is directly wrapped and solidified onto the pre-fabricated rigid skeleton 120 (hard) in a liquid or molten state, forming an integral structure with intermolecular bonding. The three-dimensional curved surface shape of the flexible body 110 is precisely guaranteed by the mold cavity, and its relative position to the skeleton 120 is permanently fixed during the manufacturing stage, eliminating displacement deviations caused by assembly tolerances and ensuring uniform stress distribution across the entire interface between the soft and hard materials. Furthermore, the skeleton 120 acts as a reinforcing rib, providing a robust and non-deformable internal reference for the entire sensor deformable body 100. All subsequent assemblies are based on this rigid skeleton 120, rather than directly locating the easily deformable flexible surface, ensuring the stability and accuracy of the assembly reference. It also absorbs some structural stress, significantly improving fatigue resistance and long-term durability. In the rigid connection with the back cover assembly, the frame 120 serves as a rigid transition between the flexible body 110 and the back cover. Through rigid connection methods such as screw fastening, high-strength adhesive bonding, or snap fasteners, it ensures that the frame forms a solid overall platform to absorb and bear assembly stress, avoiding any impact on the flexible body 110. The suspended upper electrode 400 and lower electrode 500 are sealed in a protected safe area, and the internal precision sensors operate in a stress-free environment, ensuring the reliability of product performance.

[0035] According to the test report (test report number JC2502000026-A), the measurement method for life / durability is as follows: (1) Connect the finger to be tested to the test platform; (2) Use a clamp to press the test block flat onto the front of the finger (without impact), hold for 1 second, and apply a pressure of 20N; (3) Lift the test block for 1 second; (4) Repeat the above two steps for 2 million tests. Test requirements: The finger must have no structural damage, and the finger indicators (according to general test standards) must be normal after 24 hours of rest to meet the requirements. Laboratory environment: (25+5)℃, (45±5)%RH.

[0036] Test results:

[0037]

[0038] It is evident that finger tactile sensors with a two-stage structure of soft-hard transition and rigid anchoring exhibit high reliability and durability.

[0039] As a further improvement, see Figure 4The circuit board 200 is a PCB board. The load-bearing support component 300, the circuit board 200, and the frame 120 are stacked sequentially and locked together by threaded fasteners 310 such as screws along the first direction (vertical). The threaded fasteners 310 provide a rigid connection with precisely controllable preload, locking and pressing the three together to form a sandwich composite rigid body. This facilitates disassembly, achieves vertical positioning, and enhances the overall structural strength and durability. Furthermore, the frame 120 of the inductive deformable body 100 is fixed with adhesive in a pre-reserved groove between it and the circuit board 200, reducing the space required for the fixing structure.

[0040] See Figure 5 The frame 120 or the load-bearing support component 300 has a transverse sliding groove 320. The front end of the PCB board is inserted into the sliding groove 320, and the rear end is locked by a threaded fastener 310, which releases the front end space to create a sensing area, reduces the number of screws, and prevents warping.

[0041] See Figure 6 The rear end of the force-bearing support member 300 extends upward to be flush with the inductive deformable body 100. The rear end of the skeleton 120 is locked to the rear end of the locking force-bearing support member 300 in the second direction (horizontal direction) by a threaded fastener 310. The first direction and the second direction are intersected to reduce the gap caused by the processing difference at the tail end.

[0042] 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 210. The PCB electrode pads are exposed, and the conductive foam 210 is pressed into contact with the flexible body 110. The conductive foam 210 has a deformation range, which can ensure contact and reduce the impact of processing errors.

[0043] 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 assembly structure, characterized in that: It includes a deformable inductive body, a capacitor-to-digital converter circuit, a control module, and rigid load-bearing support components; The inductive deformable body includes a flexible body and a rigid skeleton. The skeleton serves as an insert in the insert molding process. The flexible body is wrapped around the top of the insert by hot pressing or injection molding to form a soft-hard integrated structure. The two together enclose the cavity of the inductive deformable body, and the skeleton serves as the structural support for the flexible body. The bottom of the flexible body protrudes towards the cavity to form a suspended upper electrode. The upper electrode is a curved elastic electrode. 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 force-bearing support component serves as the base of the sensor and is rigidly integrated with the frame. The protrusions and electrodes are located in the enclosed space formed by the force-bearing support component, the frame, and the flexible body. 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 assembly structure according to claim 1, characterized in that: It includes a circuit board located in an enclosed space, with the lower electrode arranged on the front side of the circuit board.

3. The tactile sensor assembly structure according to claim 2, characterized in that: The circuit board is a PCB board, and the load-bearing support component, the PCB board and the frame are stacked in sequence and locked together by threaded fasteners through the first direction.

4. The tactile sensor assembly structure according to claim 3, characterized in that: The frame or load-bearing support component has a transverse sliding groove, the front end of the PCB board is inserted into the sliding groove, and the rear end is locked by a threaded fastener.

5. The tactile sensor assembly structure according to claim 3, characterized in that: The rear end of the force-bearing support member extends upward to be flush with the inductive deformation body, and the rear end of the skeleton is locked to the rear end of the force-bearing support member along the second direction by threaded fasteners, with the first direction and the second direction intersecting.

6. The tactile sensor assembly structure 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.

7. The tactile sensor assembly structure 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.

8. The tactile sensor assembly structure according to claim 1, characterized in that: 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 through a secondary molding process of conductive material and insulating material. Alternatively, the flexible body may be made of an insulating material and the raised surface may be coated with a conductive material to form an upper electrode.

9. The tactile sensor assembly structure according to claim 1, characterized in that: The flexible body is made of silicone. And / or, the skeleton is made of metal.

10. The tactile sensor assembly structure according to claim 1, characterized in that: The upper electrode is a downward-convex hemispherical or semi-ellipsoidal structure. And / or, the lower electrode has at least three, each lower electrode being uniformly surrounded along the central axis of the protrusion.

11. A robotic finger, characterized in that: Includes the tactile sensor assembly structure as described in any one of claims 1-10.

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