A humanoid dexterous finger fingertip tactile sensor

Abstract

This invention discloses a humanoid dexterous fingertip tactile sensor, belonging to the field of tactile sensor technology. It includes a fingertip shell, a flexible contact layer, a signal acquisition unit, an encapsulation layer, and three-dimensional force-sensitive units. The fingertip shell is connected to the flexible contact layer, forming a receiving cavity between them. The signal acquisition unit, the encapsulation layer, and multiple sets of three-dimensional force-sensitive units are disposed within the receiving cavity. The signal acquisition unit includes a mainboard, an FPCB board, and Hall sensors. The number of sets of three-dimensional force-sensitive units is the same as the number of Hall sensors. Each three-dimensional force-sensitive unit includes a carrier plate, a magnet, and an elastic column. The advantages of this invention are that, in the application scenario of humanoid dexterous fingertips, this humanoid dexterous fingertip tactile sensor combines the comprehensive advantages of high three-dimensional force sensitivity, real-time feedback, high spatial resolution, miniaturized integration, and suitability for mass production.

Description

Technical Field

[0001] This invention relates to the field of tactile sensor technology, specifically to a human-like dexterous fingertip tactile sensor. Background Technology

[0002] Tactile sensing is a crucial means for humanoid robots to perceive their external environment and acquire information at the end effector level. It is also a fundamental basis for robots to achieve precise movement, dexterous grasping, and human-robot interaction, and its performance largely determines the overall performance of the robot. Therefore, for robots to achieve human-like operation, they need to obtain real-time force perception and feedback through tactile sensors. Equipping robot actuators with advanced tactile sensors is of great significance for improving the robot's fine manipulation capabilities, dexterity, and perception abilities.

[0003] In the specific application scenario of human-like dexterous fingertips, existing tactile sensor technology still faces many challenges. Human fingertips have complex curvature and a rich distribution of tactile receptors. Robotic fingertip tactile sensors need to achieve three-dimensional force perception, high spatial resolution, and compliant contact characteristics similar to human skin within an extremely limited space. This places extremely high demands on the sensor's structural design, manufacturing process, and integration. On the other hand, fingertip manipulation involves multiple interaction modes such as grasping, pinching, and exploration. The sensor must simultaneously possess the ability to detect normal force, shear force, and torque to accurately identify contact states, slippage trends, and object surface textures. Currently, existing fingertip tactile sensors often struggle to simultaneously achieve multiple objectives, including multi-dimensional force detection, high spatial resolution, high sensitivity, real-time feedback, and small-size integration. Summary of the Invention

[0004] The technical problem to be solved by this invention is how to provide a tactile sensor that combines high sensitivity to three-dimensional force, real-time feedback, high spatial resolution, and miniaturized integration.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A humanoid dexterous fingertip tactile sensor includes a fingertip shell, a flexible contact layer, a signal acquisition unit, an encapsulation layer, and a three-dimensional force-sensitive unit. The fingertip shell is connected to the flexible contact layer, and a receiving cavity is formed between the fingertip shell and the flexible contact layer. The signal acquisition unit, the encapsulation layer, and multiple sets of three-dimensional force-sensitive units are disposed within the receiving cavity. The signal acquisition unit includes an acquisition motherboard, an FPCB board, and Hall sensors. The acquisition motherboard is fixed inside the fingertip shell. The FPCB board is bonded to the side of the acquisition motherboard near the flexible contact layer. Multiple Hall sensors are electrically connected to the FPCB board. The encapsulation layer is attached to the FPCB board. The number of three-dimensional force-sensitive units is the same as the number of Hall sensors. The three-dimensional force-sensitive unit includes a carrier plate, a magnet, and elastic pillars. Multiple carrier plates form a shape that mimics the shape of a human fingertip and are attached to a flexible contact layer. Each carrier plate has a magnet and multiple elastic pillars on the side away from the flexible contact layer. One magnet is positioned opposite one Hall sensor. The elastic pillars are arranged circumferentially around the magnet. The end of the elastic pillar away from the carrier plate is connected to the encapsulation layer.

[0007] This humanoid dexterous fingertip tactile sensor, in the application scenario of humanoid dexterous fingertips, has the comprehensive advantages of high three-dimensional force sensitivity, real-time feedback, high spatial resolution, miniaturized integration, and suitability for mass production.

[0008] Preferably, the outer dimensions of the fingertip shell are 35mm in length, 17mm in width, and 24mm in height.

[0009] Preferably, the flexible contact layer is integrally cast from PDMS material with a Shore hardness of 30A.

[0010] Preferably, the FPCB board is a polyimide substrate with a thickness of 0.1 mm.

[0011] Preferably, the support plate is formed by laser curing of photosensitive resin material.

[0012] Preferably, the encapsulation layer is provided with grooves corresponding to the position and number of elastic pillars.

[0013] Preferably, the magnetic poles of the magnet are perpendicular to the surface of the support plate.

[0014] Preferably, the magnet is an N35 neodymium iron boron cylindrical magnet with a diameter of 1.5 mm and a height of 1 mm.

[0015] Preferably, the elastic columns on each set of bearing plates are distributed in a rhomboid shape.

[0016] Preferably, the elastic column is a rubber column with a diameter of 1.7 mm and a height of 2.5 mm.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. By using an FPCB board as the core carrier of the signal acquisition unit and designing the three-dimensional force-sensitive unit array as a combination of a support plate, a magnet, and an elastic column, all sensing and signal processing elements are highly integrated into the limited space of the humanoid fingertip without changing the original shape and range of motion of the humanoid dexterous hand. The overall shape and size are precisely matched with the target humanoid dexterous fingertip, successfully overcoming the problem that traditional sensors are difficult to integrate in a small space.

[0018] 2. By correspondingly setting the magnet and Hall sensor, when the flexible contact layer is subjected to external force, the elastic column deforms, causing the support plate to shift and change its posture. This, in turn, causes the magnet to shift and change its posture along with the support plate, resulting in changes in the magnetic field detected by the Hall sensor, thus improving spatial resolution. Moreover, the STM32 chip on the FPCB board, as an MCU, can quickly acquire the magnetic field data output by the Hall sensor and output three-dimensional force and contact position data in real time through a decoupling algorithm. Its force detection sensitivity is high and its response time is fast, which can meet the high requirements of robots for precise force perception. Attached Figure Description

[0019] Figure 1 This is an exploded view of an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of an embodiment of the present invention. Detailed Implementation

[0020] To facilitate understanding of the technical solution of the present invention by those skilled in the art, the technical solution of the present invention will now be further described in conjunction with the accompanying drawings.

[0021] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0022] In this application, unless otherwise expressly specified and limited, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise expressly and specifically limited.

[0023] See Figure 1 and Figure 2 This embodiment discloses a humanoid dexterous fingertip tactile sensor, including a fingertip shell 1, a flexible contact layer 2, a signal acquisition unit 3, an encapsulation layer 4, and multiple sets of three-dimensional force-sensitive units 5. The fingertip shell 1 is connected to the flexible contact layer 2, and a receiving cavity is formed between the fingertip shell 1 and the flexible contact layer 2. The signal acquisition unit 3, the encapsulation layer 4, and the three-dimensional force-sensitive units 5 are disposed in the receiving cavity.

[0024] In this embodiment, the fingertip shell 1 is designed to mimic the fingertip of a human dexterous hand, and its external dimensions are 35mm in length, 17mm in width, and 24mm in height.

[0025] The flexible contact layer 2 is integrally cast from PDMS material with a Shore hardness of 30A using a mold. The PDMS material is polydimethylsiloxane, which ensures that the inner surface of the flexible contact layer 2 adheres to the three-dimensional force-sensitive unit 5. The surface of the flexible contact layer 2 can be set with fingerprint-like microstructure textures to enhance friction characteristics. The thickness distribution of the flexible contact layer 2 is optimized according to the curvature of the fingertip. The thickness is 1 mm in the force-concentrated area at the very tip of the fingertip, and gradually thins to 0.5 to 1 mm towards the sides and the root. The overall shape and size match the target humanoid dexterous fingertip, ensuring that the appearance and range of motion of the original dexterous hand are not changed after installation.

[0026] The signal acquisition unit 3 includes an acquisition motherboard 31, an FPCB board 32, Hall sensors 33, and a multiplexer (not shown in the figure). The acquisition motherboard 31 is fixed inside the fingertip shell 1. The FPCB board 32 is bonded to the side of the acquisition motherboard 31 near the flexible contact layer 2. The FPCB board is a 0.1mm thick polyimide substrate, manufactured using conventional flexible circuit board technology. The FPCB board 32 is positioned towards the fingertip shell 1, and multiple Hall sensors 33 are electrically connected to the FPCB board 32. In this embodiment, five Hall sensors 33 are provided. Specifically, an STM32 chip is used as the MCU on the FPCB board 32. The STM32 controls the channel switching of the multiplexer via the I2C bus to achieve polling acquisition of the five Hall sensors. The sampling frequency is 1kHz. The decoupling algorithm built into the MCU achieves rapid mapping from the original magnetic field data to the three-dimensional force distribution through a neural network model. The decoupled force data is transmitted externally in slave mode via the SPI interface. The master control device can be a robot joint actuator or a host computer control system, and the data update rate can reach 100Hz.

[0027] The encapsulation layer 4 is attached to the FPCB board 32 to protect the Hall sensor 33 and other electronic components from mechanical damage and vibration-induced detachment and poor soldering. Specifically, the assembled Hall sensor 33 and circuit components of the FPCB board 32 are segmented and bonded to the acquisition main board 31. The acquisition main board 31 with the Hall sensor 33 and FPCB board 32 attached is placed in a mold and potted with two-component epoxy resin. The potting height is designed to completely cover the electronic components on the FPCB board 32 and form a flat surface with a thickness of approximately 1.0 mm. During the potting process, it is important to remove air bubbles, which can be achieved through vacuum degassing or slow stirring. After potting, it is placed in a 60°C oven for 2 hours to ensure that the epoxy resin is fully cured, forming a hard and insulating protective layer. The cured encapsulation layer 4 can effectively fix the FPCB board 32 and the components on it, preventing displacement or damage during finger movement and contact.

[0028] Furthermore, multiple grooves 401 are provided on the encapsulation layer 4.

[0029] The number of three-dimensional force-sensitive units 5 is the same as the number of Hall sensors 33, which is 5 groups. The three-dimensional force-sensitive unit 5 includes a carrier plate 51, a magnet 52, and elastic pillars 53. The 5 groups of carrier plates 51 form a shape that mimics the shape of a human fingertip and are attached to the inner wall of the flexible contact layer 2, ensuring that the front end and about 2 / 3 of the sides of the fingertip are covered. A gap of 0.5mm is left between adjacent carrier plates 51 to avoid mutual interference during deformation. On the side of each carrier plate 51 away from the flexible contact layer 2, a magnet 52 and four elastic pillars 53 are bonded. One magnet 52 is positioned opposite one Hall sensor 33. The four elastic pillars 53 are arranged circumferentially around the magnet 52. The end of each elastic pillar 53 away from the carrier plate 51 is bonded to the groove 401 on the encapsulation layer 4 with a fixing adhesive.

[0030] In this embodiment, the support plate 51 is formed by laser curing of photosensitive resin material. The magnet 52 is an N35 neodymium iron boron cylindrical magnet with a diameter of 1.5 mm and a height of 1 mm. The magnet 52 is fixed at the center of the support plate 51, corresponding one-to-one with the position of the Hall sensor 33, and the magnetic pole direction of the magnet 52 is perpendicular to the surface of the support plate 51. The elastic column is a rubber column with a diameter of 1.7 mm and a height of 2.5 mm. The elastic columns 53 on each set of support plates 51 are distributed in a rhomboid shape to ensure stability under force.

[0031] The sensing surface of the Hall sensor 33 is positioned towards the three-dimensional force-sensitive unit 5, and the distance between it and the surface of the magnet 52 is controlled at 1.5 mm. This distance is determined by the height of the elastic column 53 and the embedding depth of the magnet 52. When the fingertip comes into contact with an external object, the flexible contact layer 2 transmits force to the support plate 51, causing the elastic column 53 to bend and deform, which in turn causes the support plate 51 to shift and change its posture. Consequently, the magnet 52 follows the support plate 51 and shifts its posture. The displacement of the magnet 52 causes a change in the magnetic field distribution at its corresponding Hall sensor 33, and the Hall sensor 33 outputs a corresponding voltage signal. This signal has a definite mapping relationship with the displacement of the magnet 52 and the external force it experiences.

[0032] This embodiment uses an FPCB board 32 as the core carrier of the signal acquisition unit 3, and designs the three-dimensional force-sensitive unit 5 array as a combination of a support plate 51, a magnet 52, and an elastic column 53. This achieves the high integration of all sensing and signal processing elements within the limited space of the humanoid fingertip without changing the original shape and range of motion of the humanoid dexterous hand. The overall shape and size are precisely matched with the target humanoid dexterous fingertip, successfully overcoming the problem that traditional sensors are difficult to integrate in a small space.

[0033] Furthermore, by correspondingly setting the magnet 52 with the Hall sensor 33, when the flexible contact layer 2 is subjected to external force, the elastic column 53 deforms, causing the support plate 51 to shift and change its posture. This, in turn, causes the magnet 52 to shift and change its posture along with the support plate 51, resulting in changes in the magnetic field detected by the Hall sensor 33, thus improving spatial resolution. Moreover, the STM32 chip on the FPCB board 32, acting as an MCU, can quickly acquire the magnetic field data output by the Hall sensor 33 and output three-dimensional force and contact position data in real time through a decoupling algorithm. Experimental verification shows that its force detection sensitivity can reach 0.15N, and the response time is less than 10ms, which can meet the high requirements of robots for precise force perception and solves the problems of insufficient sensitivity or lag in multi-dimensional force detection in existing solutions.

[0034] In summary, the humanoid dexterous fingertip tactile sensor in this embodiment combines the advantages of high three-dimensional force sensitivity, real-time feedback, high spatial resolution, miniaturized integration, and suitability for mass production in the application scenario of humanoid dexterous fingertips. This lays a key technical foundation for improving the fine manipulation ability, dexterity, and perception ability of humanoid robots.

[0035] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0036] The above embodiments are merely examples of implementation methods of the invention. The scope of protection of the present invention is not limited to the above embodiments. For those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A human-like dexterous finger fingertip tactile sensor, characterized by: It includes a fingertip shell, a flexible contact layer, a signal acquisition unit, an encapsulation layer, and a three-dimensional force sensing unit. The fingertip shell is connected to the flexible contact layer, and a receiving cavity is formed between the fingertip shell and the flexible contact layer. The signal acquisition unit, the encapsulation layer, and multiple sets of three-dimensional force sensing units are disposed within the receiving cavity. The signal acquisition unit includes an acquisition motherboard, an FPCB board, and Hall sensors. The acquisition motherboard is fixed inside the fingertip shell. The FPCB board is bonded to the side of the acquisition motherboard near the flexible contact layer. Multiple Hall sensors are electrically connected to the FPCB board. The encapsulation layer is attached to the FPCB board. The number of three-dimensional force-sensitive units is the same as the number of Hall sensors. The three-dimensional force-sensitive unit includes a carrier plate, a magnet, and elastic pillars. Multiple carrier plates form a shape that mimics the shape of a human fingertip and are attached to a flexible contact layer. Each carrier plate has a magnet and multiple elastic pillars on the side away from the flexible contact layer. One magnet is positioned opposite one Hall sensor. The elastic pillars are arranged circumferentially around the magnet. The end of the elastic pillar away from the carrier plate is connected to the encapsulation layer.

2. The human-like dexterous finger tactile sensor of claim 1, wherein: The fingertip shell measures 35mm in length, 17mm in width, and 24mm in height.

3. The humanoid dexterous fingertip tactile sensor according to claim 1, characterized in that: The flexible contact layer is integrally cast from PDMS material with a Shore hardness of 30A.

4. The humanoid dexterous fingertip tactile sensor according to claim 1, characterized in that: The FPCB board is a 0.1mm thick polyimide substrate.

5. The humanoid dexterous fingertip tactile sensor according to claim 1, characterized in that: The support plate is formed by laser curing of photosensitive resin material.

6. The humanoid dexterous fingertip tactile sensor according to claim 1, characterized in that: The encapsulation layer has grooves corresponding to the position and number of elastic pillars.

7. The humanoid dexterous fingertip tactile sensor according to claim 1, characterized in that: The magnetic poles of the magnet are perpendicular to the surface of the support plate.

8. The humanoid dexterous fingertip tactile sensor according to claim 1, characterized in that: The magnet is an N35 neodymium iron boron cylindrical magnet with a diameter of 1.5 mm and a height of 1 mm.

9. The humanoid dexterous fingertip tactile sensor according to claim 1, characterized in that: The elastic columns on each set of bearing plates are arranged in a diamond shape.

10. A humanoid dexterous fingertip tactile sensor according to claim 1, characterized in that: The elastic column is a rubber column with a diameter of 1.7 mm and a height of 2.5 mm.

Images