Mechanical hand and bionic mechanical finger thereof

Abstract

A bionic mechanical finger, comprising a bionic finger sleeve (100), a tactile sensing unit (200), a capacitance-to-digital converter (CDC) circuit, a digital processing circuit, and an analog switch array. By means of the design of a sensor structure and an inner insulating layer and the combination with a CDC, the tactile sensitivity comparable to or even superior to that of a human hand is obtained; the design that an upper electrode (210) is grounded and self-capacitors are used as lower electrodes (221) can ensure the precision of pressure measurement, thereby lowering the dependence on chip resources; and in combination with a restriction rule of capacitor design, the mechanical finger achieves a good response in daily grabbing scenarios. Also provided is a mechanical hand comprising the bionic mechanical finger.

Description

A robotic hand and its bionic mechanical finger Technical Field

[0001] The present invention relates to the field of anthropomorphic robots, in particular to a robot hand of anthropomorphic robots and a bionic mechanical finger thereof. Background Art

[0002] Anthropomorphic robots are a current research and development hotspot. Anthropomorphic robotic fingers utilize bionic finger sleeves to create a humanoid-like appearance. These sleeves feature windows at the fingertips, revealing the sensing surface of the tactile sensor. For example, CN202210387048.7 features a fixed groove at the distal end of the robot's fingertips, housing a pressure sensor for mechanical sensing. CN201621199954.0 demonstrates a similar approach, with exposed tactile sensors on the fingertips of a finger-shaped base module for sensing grasped objects.

[0003] A core attribute of an anthropomorphic robotic finger is achieving tactile sensitivity comparable to that of a human hand. The flexible capacitive three-dimensional force vector tactile sensor disclosed in CN201920633712.5 achieves three-dimensional force magnitude and direction perception through a protrusion on the upper electrode and an electrode array disposed below. Simultaneously, in conjunction with a capacitance-to-digital conversion circuit (CDC), such as the ADI7142 or ADI7147, it employs a Δ-∑ modulation method (see US Patent Number: 5,134,401) to directly convert the measured capacitance value into a digital value by repeatedly charging and discharging the measured capacitance and comparing it with a reference capacitance. This method improves the capacitance measurement sensitivity to the 1ff level. During testing, a single protrusion was able to achieve a pressure resolution of 0.01g, surpassing the 0.019g pressure resolution of a human finger, effectively meeting the requirement for an anthropomorphic robotic finger to mimic the tactile sensitivity of a human hand.

[0004] For an anthropomorphic robotic finger to effectively sense force, multiple protrusions designed based on the finger structure are needed to provide support for different areas, preventing local collapse or slumping. The CDC design can only sample one capacitance value at a time. Considering the electrode layout and size of the robotic finger, each sample takes approximately 3 milliseconds. More capacitance samples increase the duration of a single detection cycle. The three-dimensional force vector tactile sensor structure requires a large number of coupled CDC channels. The sensing array formed by four electrodes needs to sample at least four capacitance values. The presence of multiple protrusions on the robotic finger poses problems with the overall tactile response speed of the robotic finger. Furthermore, due to the anthropomorphic design, the robotic finger is elongated, and the lack of internal space affects chip size selection. For an integrated design, electronic analog switches such as MOS tubes are integrated on the chip to reserve space for other components. This limits the size of the CDC selection, and chip resources are very limited / small.

[0005] Summary of the Invention

[0006] The present invention aims to achieve the tactile sensitivity of a robotic finger similar to that of a human hand under the premise of anthropomorphism, and at the same time, to fully utilize limited / small amounts of chip resources to solve the response speed problem of the robotic finger.

[0007] To this end, a bionic mechanical finger is provided, including a bionic finger sleeve, a tactile sensing unit, a capacitance-to-digital conversion circuit, a digital processing circuit, and an analog switch array; the bionic finger sleeve is hollow, and the tactile sensing unit, the capacitance-to-digital conversion circuit, the digital processing circuit, and the analog switch array are built into the hollow part of the bionic finger sleeve; the tactile sensing unit is provided with at least one flexible upper electrode, which is located at the fingertip and / or fingertip, and is exposed through a window of the bionic finger sleeve or attached to a corresponding flexible part of the bionic finger sleeve, and the upper electrode forms an anthropomorphic shape on the upper side and forms a There are protrusions, the outer surface of each protrusion is an elastic curved surface, all the upper electrodes together form at least one main protrusion and at least one auxiliary protrusion, the main protrusion is located below the arched part of the fingertips and / or fingertips, at least three lower electrodes are provided below the main protrusion, auxiliary protrusions are provided at other positions, one or two lower electrodes are provided below the auxiliary protrusions, an inner insulating layer with a thickness of between 10 nanometers and 1 millimeter is provided between each protrusion and the corresponding lower electrode, the downward projection of the protrusion covers at least part of the area of ​​each corresponding lower electrode, and the indirect contact area of ​​the protrusion on each corresponding lower electrode involved in the deformation change of the upper electrode due to external force; the upper electrode is configured to couple with the ground when the bionic mechanical finger contacts the touch object, and to form X mutual capacitances or self-capacitances before the bionic mechanical finger contacts the touch object, where X is zero, one or more; each lower electrode involved in pressure detection is coupled to the acquisition channel of the capacitance-to-digital conversion circuit through the analog switch array, and constructs a self-capacitance as a self-capacitance detection electrode when the bionic mechanical finger contacts the touch object, wherein the lower electrode of the main protrusion forms Y self-capacitances, Y ≥ 3, and the lower electrode of the auxiliary protrusion The electrodes form Z self-capacitors, Z ≥ 1; the number of each capacitor formed is configured to have a limiting relationship K1*X+K2*Y+K3*Z ≤ N, N is 0.05-0.02 seconds, where K1 is the sampling time of a single corresponding capacitor determined by the size of the upper electrode, K2 is the sampling time of a single self-capacitor determined by the size of the lower electrode of the main protrusion, and K3 is the sampling time of a single self-capacitor determined by the size of the lower electrode of the auxiliary protrusion; a digital processing circuit, used for logic processing and / or logic sequence control, is coupled to the capacitance-to-digital conversion circuit.

[0008] The implementation of the present invention can achieve the following technical effects: with the help of the sensor structure, the design of the inner insulating layer and the cooperation of CDC, the tactile sensitivity comparable to or even exceeding that of human hands is achieved. The design of the upper electrode being grounded and the lower electrode adopting self-capacitance can ensure the accuracy of pressure detection, reduce dependence on chip resources, and cooperate with the restriction rules of capacitor design to achieve good response of mechanical fingers in daily grasping scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1a shows the structure of an exemplary biomimetic robotic finger window design;

[0010] Figure 1b shows the structure of an exemplary integrated bionic robotic finger;

[0011] FIG2 shows the composition of an exemplary tactile sensing unit;

[0012] FIG3 shows a schematic diagram of the structure of the flexible upper electrode and the housing assembly;

[0013] Figure 4 shows a schematic diagram of the control module structure;

[0014] Figure 5 shows a schematic diagram of the contact between the lower electrode plate and the flexible upper electrode;

[0015] FIG6 shows a schematic diagram of the inner insulating layer between the protrusion and the lower electrode;

[0016] Figure 7 shows a schematic diagram of the coupling of upper and lower electrode channels;

[0017] Figure 8 shows a schematic diagram of proximity detection using self-capacitance;

[0018] Figure 9a shows the coupling structure of the conductive bionic finger cuff and the control module;

[0019] Figure 9b shows the coupling structure between the conductive middle frame and the control module;

[0020] FIG10 is a schematic diagram showing the mutual capacitance formed by multiple electrodes;

[0021] Figure 11a shows the design of the thumb bump;

[0022] Figure 11b shows a schematic diagram of the raised design of the middle finger or index finger;

[0023] FIG11c shows a schematic diagram of the raised design of the ring finger; and

[0024] FIG11 d shows a schematic diagram of the raised design of the little finger. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0026] Figures 1a and 1b illustrate the appearance and structure of an exemplary biomimetic robotic finger. This biomimetic robotic finger is formed into a bionic shape that mimics a human finger using a biomimetic finger cuff 100. The biomimetic finger cuff 100 is hollow, housing a tactile sensing unit 200. The biomimetic finger cuff 100 is insulated from the tactile sensing unit 200.

[0027] Figure 2 illustrates the components of an exemplary tactile sensing unit 200. The tactile sensing unit 200 includes a flexible upper electrode 210, a control module 220, and a housing assembly 230. The upper electrode 210 is located on the fingertips and / or fingertips and can be exposed through a window in the bionic finger cuff 100, as shown in Figure 1a, or completely concealed within the cuff, as shown in Figure 1b, and adhered to the flexible thin wall of the bionic finger cuff 100 to maintain force conduction.

[0028] Figure 3 shows a schematic diagram of the flexible upper electrode and housing assembly. The flexible upper electrode serves as an inner conductive layer 211, with an outer insulating layer 212 disposed on the surface of the inner conductive layer 211. The housing assembly 230 includes a middle frame 231 and a rear cover 232. The middle frame 231 supports and secures the control module 220 and the flexible upper electrode 210.

[0029] FIG4 shows a schematic diagram of the control module structure. The control module 220 includes a lower electrode plate 221, a control circuit board 222, and a capacitance-to-digital conversion circuit (CDC), a digital processing circuit, and an analog switch array integrated in the control circuit board 222. The digital processing circuit can be a sequential controller that implements logical sequence control entirely through hardware, or the digital processing circuit can be a microprocessor such as a CPU, MCU, etc., which achieves logical processing and logical sequence control through a combination of software and hardware. The analog switch array can be formed into an on-off control array using, for example, MOS tubes to achieve high-speed electrical control. The lower electrode plate 221 and the control circuit board 222 can be combined into a control module circuit board.

[0030] Figure 5 shows a schematic diagram of the contact between the lower electrode plate and the flexible upper electrode. The inner conductive layer 211 can be configured as conductive silicone, and the surface insulating layer 212 is made of waterproof, wear-resistant, and anti-static material. It can be configured as insulating paint or insulating film, such as insulating silicone. The two are manufactured through an integrated injection molding process, so that there is no air gap between the two, no displacement occurs, and the conduction of force is guaranteed. The upward side of the inner conductive layer 211 forms an anthropomorphic shape, simulating the appearance of a human finger. A protrusion is formed on the downward side, and the outer surface of each protrusion is a downward convex elastic surface.

[0031] The number of upper electrodes can be one or more. The former solution is formed by laying insulating silicone on the outside of a whole piece of conductive silicone, and the latter solution can be formed by laying a whole piece of insulating silicone on the outside of multiple pieces of mutually insulated conductive silicone located in different areas. Regardless of whether there is one or more upper electrodes, all upper electrodes together form at least one main protrusion 2111 and at least one auxiliary protrusion 2112. The main protrusion 2111 is located below the arched part of the fingertips and / or fingertips. At least three lower electrodes 221 are provided below the main protrusion 2111. This area is most sensitive to force and cooperates with the main protrusion to achieve three-dimensional force detection. The auxiliary protrusion 2112 is provided at other locations as needed for mechanical testing and is reused as a support to prevent regional collapse of the conductive silicone 211. One or two lower electrodes 221 are provided below the auxiliary protrusion 2112 to cooperate with the auxiliary protrusion 2112 to achieve normal force or two-dimensional force detection. The downward projections of the protrusions 2111 and 2112 cover at least part of the area of ​​each corresponding lower electrode, and the indirect contact area of ​​the protrusion on each corresponding lower electrode involved in the deformation of the upper electrode due to external force. Indirect contact refers to the contact between the upper electrode and the lower electrode through the inner insulating layer. As shown in Figure 6, an inner insulating layer 222 with a thickness of between 10 nanometers and 1 mm is provided between each protrusion and the corresponding lower electrode. The inner insulating layer 222 is formed by a coating of insulating ink. If the thickness of the insulating ink is 10 microns, the dielectric constant of the insulating ink is 3. According to the capacitance formula C = ε r *ε0*A / d,ε0=8.854187817x 10 -12 F / m, ε0 is the dielectric constant of vacuum, ε r is the relative dielectric constant, 1mm 2 The contact area capacitance is 886*3=2.66pF. The actual capacitance is the series connection of the air capacitance and the insulating ink. When the distance is 10 microns, the capacitance becomes the series connection of 0.886pF and 2.66pF, which will drop to 0.66pF, a change equivalent to 2pF. According to the high-precision capacitance measurement of the above-mentioned sensing structure, the change can reach 4 million. If MEMS technology is used, the insulating coating can be made into 1um and 0.1mm. 2 Just change.

[0032] The upper electrode 210 is configured to couple to ground when the bionic robotic finger contacts the touch object, and to form X mutual capacitances or self-capacitances before the bionic robotic finger contacts the touch object, where X is zero, one, or more. It is important for the upper electrode 210 to couple to ground when the bionic robotic finger contacts the touch object. Coupling to ground provides a shield. For capacitance, the effects of the ambient electric field and the robot's own metal components on detection need to be considered. Ground shielding effectively prevents external electric field interference during force measurement and provides ground capacitance for the lower electrode when performing self-capacitance detection. The mutual capacitance or self-capacitance formed by the upper electrode 210 before the bionic robotic finger contacts the touch object is primarily used to form proximity sensing, detecting the proximity of external objects. Zero means turning off or canceling the proximity sensing function, and the upper electrode simply serves as a ground shield for pressure detection. In this alternative, the upper electrode can be directly connected to the ground wire on the circuit board. One allows for basic proximity sensing, while more, such as forming two or more mutual capacitances with different effective sensing electric field heights, can further sense the relative approaching speed of an object based on proximity sensing. As shown in FIG7 , for situations where proximity sensing is desired, a digital processing circuit can be provided to time-share couple the upper electrode to the acquisition channel or ground of the capacitance-to-digital conversion circuit through an analog switch array.

[0033] Referring further to Figure 7 , each lower electrode involved in pressure detection is coupled to the acquisition channel of the capacitance-to-digital conversion circuit via an analog switch array. When the bionic robotic finger contacts a touch object, it serves as a self-capacitance detection electrode, forming a self-capacitance. The advantage of using self-capacitance detection for the lower electrodes is that it reduces the number of analog switches used by at least twice as compared to mutual capacitance. Analog switches are essentially integrated on the chip, thus reducing chip resource requirements and facilitating the design of anthropomorphic robotic fingers. In the self-capacitance detection scheme, the lower electrodes of the main protrusions form Y self-capacitors, where Y ≥ 3, and the lower electrodes of the auxiliary protrusions form Z self-capacitors, where Z ≥ 1. To address the issue of loudness speed, the number of capacitors formed must be configured to meet the constraint of K1*X+K2*Y+K3*Z≤N, where N is 0.05-0.02 seconds. K1 is the sampling time of a single corresponding capacitor determined by the size of the upper electrode, K2 is the sampling time of a single self-capacitor determined by the size of the lower electrode of the main protrusion, and K3 is the sampling time of a single self-capacitor determined by the size of the lower electrode of the auxiliary protrusion. The above relationship establishes design rules for the number and size of electrodes in an anthropomorphic robotic finger. This rule ensures a good response for everyday grasping scenarios. The lower limit of N (30Hz frequency) determines the response required to meet basic scenario requirements. The upper limit is not necessarily better; exceeding 0.02s (100Hz frequency) negatively impacts pressure detection performance.

[0034] Figure 7 illustrates the structural design of a capacitance-to-digital conversion circuit coupled to electrodes via an analog switch array. In situations where proximity detection is required, based on the structure of Figure 7, as an optional software implementation, the proximity detection capacitor and the self-capacitance of each lower electrode can be sampled sequentially and time-shared within each detection cycle. The machine continuously cycles through detection cycles, sampling each capacitor time-shared within each detection cycle. The digital processing circuit can be implemented using a sequence controller, with the raw data transmitted via external interface 300 for external processing. Alternatively, the digital processing circuit can be implemented using a microprocessor for local processing, with the processing results transmitted via external interface 300. If the digital processing circuit is equipped with a microprocessor, as a further improved option, the microprocessor can be configured to control the analog switch array to couple the upper electrode to the capacitance-to-digital conversion circuit to form proximity detection before the bionic mechanical finger contacts the touch object, and to control the analog switch array to couple the upper electrode to ground to form a shield after the bionic mechanical finger contacts the touch object. In other words, by directly dividing the upper electrode into two states, before and after contact, the boundary helps save computing power resources. Furthermore, the processor's built-in algorithm analyzes the pressure changes in the self-capacitance of each lower electrode, reducing computing power requirements. Furthermore, a spike neural network (SNN) is used to analyze the capacitance obtained by sampling the upper electrode for proximity detection. Due to the small number of proximity detection capacitors and their complex characteristics, the SNN analysis method significantly improves accuracy. The combination of these two analysis methods achieves a good balance in all aspects.

[0035] Figure 8 shows a schematic diagram of proximity detection using self-capacitance. During the coupling period between the upper electrode and the capacitance-to-digital conversion circuit, the capacitance-to-digital conversion circuit is configured to obtain at least the self-capacitance of the upper electrode. Self-capacitance offers the advantage of a longer sensing distance compared to mutual capacitance in proximity detection. Mutual capacitance is less sensitive to the environment and allows the formation of electric fields of varying heights to further analyze approach speed. Both have their strengths and weaknesses, and can be selected in combination depending on the application, or both can be used together to sense proximity.

[0036] There are many different approaches to mutual capacitance proximity sensing. As examples, three examples are provided below to illustrate the approach.

[0037] As an optional exemplary embodiment, referring to Figures 1a, 1b, 3, and 9a, the bionic finger cuff 100 has a conductive function and can be used to shield the signal and eliminate external interference. The outward surface of the bionic finger cuff 100 needs to be insulated, including but not limited to insulating paint or insulating film, and the upper electrode is insulated from the bionic finger cuff 100. The middle frame 231 is made of insulating material to isolate the control module 220 from the bionic finger cuff 100, thereby isolating the bionic finger cuff 100 from most areas of the control module 220. The middle frame 223 is provided on the circuit board to support the upper electrode. The lower electrode is provided on the top surface of the circuit board. The raised curved surface passes through the middle frame 223 and indirectly contacts the lower electrode through the inner insulating layer. A window is left in the middle frame 231, near the tail, where the force is small and it is not easily affected by deformation. The control module 220 leaves a bionic finger cuff connection module 223 at a designated position, including but not limited to the use of an elastic probe, so that the corresponding interface 224 of the control circuit board 222 is connected to the bionic finger cuff 100. The microprocessor on the control circuit board 222 controls the coupling or disconnection of the bionic finger cuff 100 with the ground through the analog switch array, and / or the capacitance-to-digital conversion circuit couples the bionic finger cuff through the analog switch array, which can control the bionic finger cuff 100 as a ground signal, shielding other interference and improving test accuracy. The bionic finger cuff 100 can also be set as an electrode, which can be used as a self-capacitor and / or form a mutual capacitance with the upper electrode for use as a proximity sensor. Furthermore, during the coupling period between the upper electrode and the capacitance-to-digital conversion circuit, the capacitance-to-digital conversion circuit is configured to at least obtain the mutual capacitance between the upper electrode and the bionic finger cuff as a mutual capacitance proximity sensing scheme. After the bionic mechanical finger contacts the touch object, the microprocessor controls the bionic finger cuff and the upper electrode to be coupled to ground via the analog switch array, both of which form a shield that surrounds the lower electrode. Referring to Figures 1a and 3, the bionic finger cuff 100 is provided with a window, and the outer surface of the upper electrode is covered with an outer insulating layer 212 and exposed through the window through the outer insulating layer 212; alternatively, referring to Figure 1b, the portion of the bionic finger cuff 100 covering the upper electrode is insulated from the rest of the bionic finger cuff, and the rest of the bionic finger cuff has conductive properties for time-sharing coupling to the acquisition channel or ground of the capacitance-to-digital conversion circuit.

[0038] As another optional exemplary embodiment, referring to Figures 1a, 1b, 3, and 9b, the bionic finger sleeve 100 is made of an insulating material, and the middle frame 231 is made of a metal material. It is provided on the circuit board and is used to support and fix the control module 220 and the upper electrode 210. The middle frame 231 is located around the upper electrode, and the surface in contact with the upper electrode is insulated to form a middle frame insulation layer 233, including but not limited to spraying insulating paint or coating, so as to insulate and isolate the upper electrode from the middle frame 231. The control module 220 includes a middle frame connection flexible body 223 and an external interface 224. The middle frame connection flexible body 223 can be configured as a conductive cloth and is arranged at a specified position between the control circuit board 222 and the middle frame 231 to ensure stable connection and conduction between the control circuit board 222 and the middle frame 231 while locking the control circuit board 222 and the middle frame 231. The middle frame 231 is connected to the control circuit board 222 through the middle frame connection flexible body 223, wherein the microprocessor controls the coupling or disconnection of the middle frame 231 with the ground through the analog switch array, and / or the capacitance digital conversion circuit couples the middle frame 231 through the analog switch array, so that the middle frame 231 can be used as a ground signal, shielding other interference and improving the test accuracy. At the same time, the middle frame 231 can also be set as an electrode, which can be used as a self-capacitor and / or form a mutual capacitance with the upper electrode to detect proximity. Further, the bottom of the middle frame is fixed to the circuit board, and the upper electrode, the middle frame, and the circuit board form an enclosed space to achieve the improvement of the firmness of the sensing structure; during the coupling period between the upper electrode and the capacitance digital conversion circuit, the capacitance digital conversion circuit is configured to at least obtain the mutual capacitance between the upper electrode and the middle frame as a mutual capacitance proximity detection. After the bionic mechanical finger contacts the touch object, the microprocessor controls the middle frame and the upper electrode to be coupled to the ground together through the analog switch array, and together with the upper electrode, covers the internal lower electrode to form a shield.

[0039] As another optional exemplary solution, Figure 10 shows a schematic diagram of a plurality of electrodes forming mutual capacitance. In the case of multiple top electrodes, the top electrodes are insulated from each other, and each top electrode is time-sharedly coupled to a capture channel or ground of a capacitance-to-digital conversion circuit via an analog switch array. Furthermore, during the coupling period between the top electrodes and the capacitance-to-digital conversion circuit, the capacitance-to-digital conversion circuit is configured to at least obtain the mutual capacitance between each top electrode. After the bionic mechanical finger contacts the touch object, the microprocessor controls the coupling of each top electrode to ground via the analog switch array.

[0040] Taking into account the bionic characteristics, usage frequency and main forces of the five fingers of the human body when grasping, targeted protrusion position distribution design is implemented for the thumb, middle finger, index finger, ring finger and little finger.

[0041] Figure 11a illustrates the design of the thumb protrusion. When the bionic finger sleeve is mounted on the thumb of a robotic hand, the tactile sensing unit is equipped with a first upper electrode based on the bionic structure of the thumb. The first upper electrode is located in the fingertip area. Below the first upper electrode are a first primary protrusion 21111 and a first auxiliary protrusion 21121. The first primary protrusion 21111, located below the arch of the fingertip, serves as the first sensing unit for detecting three-dimensional force on the fingertip. The first auxiliary protrusion 21121, located at the front of the fingertip, serves as the second sensing unit for detecting force on the front of the fingertip. Because thumbs are relatively short, protrusions on the fingertip can generally meet the need for force sensing. The first primary protrusion 21111 is located on the arch of the fingertip to sense three-dimensional force. Considering the action of poking with the fingertip, the first auxiliary protrusion 21121 is located at the front of the fingertip to achieve head sensing and simultaneously support the upper electrode with the primary protrusion.

[0042] Figure 11b shows a schematic diagram of the protrusion design of the middle finger or index finger. When the bionic finger sleeve is used to be placed on the middle finger or index finger of a manipulator, the tactile sensing unit is provided with a first upper electrode and a second upper electrode according to the bionic structure of the middle finger or index finger. The first upper electrode is located in the fingertip area of ​​the middle finger or index finger, and the second upper electrode is located in the fingertip area of ​​the middle finger or index finger. The first upper electrode and the second upper electrode serve as mutual capacitance electrodes for detecting proximity. A first main protrusion 21111 and a first auxiliary protrusion 21121 are provided below the first upper electrode. The first main protrusion is located below the arched part of the fingertip as the first sensing unit for detecting the three-dimensional force of the fingertip. The first auxiliary protrusion is located at the front end of the fingertip as the second sensing unit for detecting the force at the front end of the fingertip. A second main protrusion 21112 is provided below the second upper electrode. The second main protrusion 211112 is located below the arched part of the fingertip as the third sensing unit for detecting the three-dimensional force of the fingertip. The middle finger or index finger is relatively slender and is used frequently in daily life. As the main force sensing design of the finger, the arch of the fingertip and fingertip forms two three-dimensional force sensing and head force sensing, achieving the main force identification of grasping. At the same time, mutual capacitance completes material identification based on the different dielectrics of the objects.

[0043] Figure 11c illustrates the design of the protrusion for the ring finger. When the bionic finger sleeve is attached to the ring finger of a robotic hand, the tactile sensing unit includes a first upper electrode and a second upper electrode. The first upper electrode is located at the tip of the ring finger, and the second upper electrode is located at the front of the fingertip. These electrodes serve as mutual capacitance electrodes for proximity sensing. Below the first upper electrode are a first primary protrusion 21111 and a first auxiliary protrusion 21121. The first primary protrusion 21111, located below the arch of the fingertip, serves as the first sensing unit for detecting three-dimensional force on the fingertip. The first auxiliary protrusion 21121, located at the front of the fingertip, serves as the second sensing unit for detecting force on the front of the fingertip. Below the second upper electrode are a second auxiliary protrusion 21122, which serves as the third sensing unit for detecting normal force on the fingertip. The ring finger serves as an auxiliary gripper. Three-dimensional force detection of the fingertip arch and head force sensing are implemented, complementing normal force detection on the fingertip. Mutual capacitance also enables material identification based on dielectric differences.

[0044] Figure 11d shows a schematic diagram of the pinky finger protrusion design. When the bionic finger sleeve is attached to the pinky finger of a robotic hand, the tactile sensing unit is equipped with a first upper electrode, located at the tip and front of the pinky finger. Below the first upper electrode are a first primary protrusion 21111, a first auxiliary protrusion 21121, and a second auxiliary protrusion 21122. The first primary protrusion 21111, located below the arch of the fingertip, serves as the first sensing unit for detecting three-dimensional force on the fingertip. The first auxiliary protrusion 21121, located at the front of the fingertip, serves as the second sensing unit for detecting force on the front of the fingertip. The second auxiliary protrusion 21122, located below the front of the fingertip, serves as the third sensing unit for detecting normal force on the fingertip. The pinky finger is longer than the thumb and shorter than the middle, index, or ring fingers, contributing less to grasping and thus eliminating the need for material recognition. The provision of three-dimensional force detection on the fingertip arch and head force sensing, combined with normal force detection on the fingertip, satisfies the force sensing task for this type of finger.

[0045] Furthermore, the elastic surface is spherical, and when pressed, the indirect contact area changes by an order of magnitude from point contact to surface contact, ensuring high pressure detection sensitivity. The radius of the main protrusion is larger than the auxiliary protrusion, which plays the primary role in force detection. The radius of the main protrusion ranges from 0.3 to 5mm. Based on the spherical surface, the size of the protrusion affects the detection range and sensitivity. When the protrusion is less than 0.3mm, the hemisphere is flattened when pressed, and the detection range is too small. When the protrusion is greater than 5mm, the finger contact force causes too much deformation of the hemisphere, resulting in a decrease in sensitivity.

[0046] Furthermore, the copper layer on the top surface of the circuit board forms each lower electrode. As an optional solution, the circuit board is set to have a thickness of at least 0.1 mm, and the influence of the robot's own metal on the lower electrode is isolated or attenuated by the thickness; or, if space does not allow, the circuit board is made of a thin plate, and an active shielding layer is provided on the bottom surface of the circuit board to isolate the influence of the robot's own metal through ground shielding or equipotential shielding; or, if space is sufficient, the circuit board is designed to be thick enough and to form an active shield.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A bionic mechanical finger, characterized in that: It includes a bionic finger sleeve, a tactile sensing unit, a capacitance-to-digital conversion circuit, a digital processing circuit, and an analog switch array; The bionic finger sleeve is hollow, and the tactile sensing unit, the capacitance digital conversion circuit, the digital processing circuit, and the analog switch array are built into the hollow part of the bionic finger sleeve; The tactile sensing unit is provided with at least one flexible upper electrode, which is located at the finger pulp and / or fingertip, exposed through the bionic finger sleeve window or attached to the corresponding flexible part of the bionic finger sleeve, the upper electrode forms an anthropomorphic shape on the upper side, and forms a protrusion on the lower side, the outer surface of each protrusion is an elastic curved surface, all the upper electrodes together form at least one main protrusion and at least one auxiliary protrusion, the main protrusion is located below the arched part of the finger pulp and / or fingertip, at least three lower electrodes are arranged below the main protrusion, the auxiliary protrusion is arranged at other positions, one or two lower electrodes are arranged below the auxiliary protrusion, an inner insulating layer with a thickness of 10 nanometers to 1 millimeter is arranged between each protrusion and the corresponding lower electrode, the downward projection of the protrusion at least covers a part of the area of ​​each corresponding lower electrode, and the indirect contact area of ​​the protrusion involved in the deformation change of the upper electrode due to external force on each corresponding lower electrode; The upper electrode is configured to couple with the ground when the bionic mechanical finger contacts the touch object, and to form X mutual capacitances or self capacitances before the bionic mechanical finger contacts the touch object, where X is zero, one or more; Each lower electrode involved in pressure detection is coupled to the acquisition channel of the capacitance digital conversion circuit through the analog switch array, and is used as a self-capacitance detection electrode to construct a self-capacitance when the bionic mechanical finger contacts the touch object, wherein the main raised lower electrodes constitute Y self-capacitances, Y≥3, and the auxiliary raised lower electrodes constitute Z self-capacitances, Z≥1; The number of each capacitor formed is configured to have a limiting relationship K1*X+K2*Y+K3*Z≤N, N is 0.05-0.02 seconds, where K1 is the sampling time of a single corresponding capacitor determined by the size of the upper electrode, K2 is the sampling time of a single self-capacitor determined by the size of the lower electrode of the main protrusion, and K3 is the sampling time of a self-single capacitor determined by the size of the lower electrode of the auxiliary protrusion; A digital processing circuit for logic processing and / or logic sequence control is coupled to the capacitance digital conversion circuit. combine.

2. The bionic mechanical finger according to claim 1, characterized in that: The digital processing circuit couples the upper electrode to the collection channel or ground of the capacitance digital conversion circuit in a time-sharing manner through the analog switch array.

3. The bionic mechanical finger according to claim 2, characterized in that: The digital processing circuit is a microprocessor; The microprocessor is configured to control the analog switch array to couple the upper electrode with the capacitance-to-digital conversion circuit to form proximity detection before the bionic mechanical finger contacts the touch object, and to control the analog switch array to couple the upper electrode with the ground to form shielding after the bionic mechanical finger contacts the touch object.

4. The bionic mechanical finger according to claim 2 or 3, characterized in that: According to the self-capacitance change characteristics of each lower electrode, the pressure situation is analyzed based on the built-in algorithm of the processor; Furthermore, the capacitance obtained by sampling the upper electrode as proximity detection is analyzed using an SNN pulse neural network.

5. The bionic mechanical finger according to claim 2, characterized in that: During the coupling of the upper electrode with the capacitance-to-digital conversion circuit, the capacitance-to-digital conversion circuit is configured to obtain at least the self-capacitance of the upper electrode.

6. The bionic mechanical finger according to claim 2, characterized in that: The bionic finger sleeve has the ability to conduct electricity, and the upper electrode is insulated from the bionic finger sleeve; The microprocessor controls the bionic finger cuff to couple or disconnect with the ground through the analog switch array, and / or the capacitance digital conversion circuit couples the bionic finger cuff through the analog switch array.

7. The bionic mechanical finger according to claim 6, characterized in that: During the coupling between the upper electrode and the capacitance-to-digital conversion circuit, the capacitance-to-digital conversion circuit is configured to at least obtain the mutual capacitance between the upper electrode and the bionic finger cuff; After the bionic mechanical finger contacts the touch object, the microprocessor controls the bionic finger sleeve and the upper electrode to be coupled to the ground through the analog switch array.

8. The bionic mechanical finger according to claim 6, characterized in that: The tactile sensing unit is provided with a middle frame, a circuit board fixed with a capacitance digital conversion circuit and an analog switch array; The middle frame is arranged on the circuit board to support the upper electrode, the lower electrode is arranged on the top surface of the circuit board, and the raised curved surface passes through the middle frame and indirectly contacts the lower electrode through the inner insulating layer.

9. The bionic mechanical finger according to claim 6, characterized in that: The bionic finger sleeve is provided with a window, and the outer surface of the upper electrode is covered with an outer insulating layer and is exposed through the window through the outer insulating layer; Alternatively, the portion of the bionic finger cuff covering the upper electrode is insulated from other portions of the bionic finger cuff, and the other portions have conductive properties to be time-sharingly coupled to a collection channel or ground of the capacitance-to-digital conversion circuit.

10. The bionic mechanical finger according to claim 2, characterized in that: The bionic finger sleeve is insulated, and the tactile sensing unit is provided with a circuit board and a conductive middle frame; The middle frame is arranged on the circuit board and used to support the upper electrode, and the middle frame is located around the upper electrode and is insulated from the upper electrode; The microprocessor controls the coupling or disconnection of the middle frame with the ground through the analog switch array, and / or the capacitance digital conversion circuit couples the middle frame through the analog switch array.

11. The bionic mechanical finger according to claim 10, characterized in that: The bottom of the middle frame is fixed to the circuit board, and the upper electrode, the middle frame and the circuit board form an enclosed space; During the coupling between the upper electrode and the capacitance-to-digital conversion circuit, the capacitance-to-digital conversion circuit is configured to obtain at least the mutual capacitance between the upper electrode and the middle frame; After the bionic mechanical finger contacts the touch object, the microprocessor controls the middle frame and the upper electrode to be coupled to the ground through the analog switch array.

12. The bionic mechanical finger according to claim 2 or 3, characterized in that: The upper electrodes have at least two electrodes which are insulated from each other; Each upper electrode is time-sharingly coupled to a collection channel or ground of a capacitance digital conversion circuit through an analog switch array.

13. The bionic mechanical finger according to claim 12, characterized in that: During the coupling between the upper electrode and the capacitance-to-digital conversion circuit, the capacitance-to-digital conversion circuit is configured to obtain at least Taking the mutual capacitance between each upper electrode; After the bionic mechanical finger contacts the touch object, the microprocessor controls each upper electrode to be coupled to the ground through the analog switch array.

14. The bionic mechanical finger according to claim 1, characterized in that: The bionic finger sleeve is used to be placed on the thumb of a manipulator. The tactile sensing unit is provided with a first upper electrode, which is located in the fingertip area of ​​the thumb or the ring finger. A first main protrusion and a first auxiliary protrusion are provided below the first upper electrode. The first main protrusion is located below the arched part of the fingertip as a first sensing unit for detecting the three-dimensional force of the fingertip, and the first auxiliary protrusion is located at the front end of the fingertip as a second sensing unit for detecting the force on the front end of the fingertip.

15. The bionic mechanical finger according to claim 1, characterized in that: The bionic finger sleeve is used to be placed on the middle finger or index finger of a manipulator, and the tactile sensing unit is provided with a first upper electrode and a second upper electrode. The first upper electrode is located in the fingertip area of ​​the middle finger or index finger, and the second upper electrode is located in the fingertip area of ​​the middle finger or index finger. The first upper electrode and the second upper electrode serve as mutual capacitance electrodes for detecting proximity. A first main protrusion and a first auxiliary protrusion are provided below the first upper electrode. The first main protrusion is located below the arched part of the fingertip as a first sensing unit for detecting three-dimensional force of the fingertip, and the first auxiliary protrusion is located at the front end of the fingertip as a second sensing unit for detecting force on the front end of the fingertip. A second main protrusion is provided below the second upper electrode, and the second main protrusion is located below the arched part of the fingertip as a third sensing unit for detecting three-dimensional force of the fingertip.

16. The bionic mechanical finger according to claim 1, characterized in that: The bionic finger sleeve is used to be placed on the ring finger of a manipulator. The tactile sensing unit is provided with a first upper electrode and a second upper electrode. The first upper electrode is located in the fingertip area of ​​the ring finger, and the second upper electrode is located in the front part of the finger pulp of the ring finger. The first upper electrode and the second upper electrode serve as mutual capacitance electrodes for detecting proximity. A first main protrusion and a first auxiliary protrusion are provided below the first upper electrode. The first main protrusion is located below the arched part of the fingertip as a first sensing unit for detecting the three-dimensional force of the fingertip. The first auxiliary protrusion is located at the front end of the fingertip as a second sensing unit for detecting the force on the front end of the fingertip. A second auxiliary protrusion is provided below the second upper electrode, and the second auxiliary protrusion serves as a third sensing unit for detecting the normal force of the finger pulp.

17. The bionic mechanical finger according to claim 1, characterized in that: The bionic finger sleeve is used to be placed on the little finger of a manipulator. The tactile sensing unit is provided with a first upper electrode, and the first upper electrode is located in the fingertip area and the front part of the finger pulp of the little finger. A first main protrusion, a first auxiliary protrusion, and a second auxiliary protrusion are provided below the first upper electrode. The first main protrusion is located below the arched part of the fingertip as a first sensing unit for detecting the three-dimensional force of the fingertip, the first auxiliary protrusion is located at the front end of the fingertip as a second sensing unit for detecting the force at the front end of the fingertip, and the second auxiliary protrusion is located below the front part of the finger pulp as a third sensing unit for detecting the normal force of the finger pulp.

18. The bionic mechanical finger according to claim 1, characterized in that: The outer surface of the protrusion is a spherical curved surface, and the radius of the main protrusion is larger than that of the auxiliary protrusion.

19. The bionic mechanical finger according to claim 18, characterized in that: The radius size of the main protrusion is between 0.3-5mm.

20. The bionic mechanical finger according to claim 1, characterized in that: It comprises a circuit board, wherein the copper layer on the top surface of the circuit board forms each of the lower electrodes; The circuit board has a thickness of at least 0.1 mm, and / or an active shielding layer is arranged on the bottom surface of the circuit board.

21. A robot arm, characterized in that: Comprising a bionic mechanical finger as described in any one of claims 1-20.

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