A SCM intelligent self-sensing joint hinge and method for micro-robots

Abstract

The present invention discloses an SCM intelligent self-sensing joint hinge and method for a micro robot, belonging to the technical field of micro robots. The present invention designs an SCM hinge embedded with a piezoresistive film sensor, which is processed on a polyimide film in the middle of the SCM hinge and is composed of a microstructure etching pattern, a metal electrode and a carbon nanotube film. The sensor uses a microstructure to make the surface of the polyimide film anisotropic, thereby increasing its deformation when the hinge is bent. At the same time, the carbon nanotube film coated on the microstructure will produce stronger cracks, amplifying the impedance changes detected by the metal electrode, and improving the accuracy of bending angle perception. The present invention will not affect the structure of the SCM hinge itself, and has the advantages of a simple preparation process and easy batch production, providing a new, efficient and accurate solution for micro robot joint angle sensing.

Description

Technical Field

[0001] The present invention belongs to the technical field of microrobots, and in particular relates to an SCM intelligent self-sensing joint hinge and method for a microrobot. Background Art

[0002] In the current research on closed-loop control of robot posture, robots usually rely on sensors installed at key joints to sense joint posture and achieve precise control of the overall robot posture. Although these sensors can provide accurate joint posture information, their size and weight limit their direct application in micro robot joints.

[0003] Therefore, although current micro-robots can achieve fairly high transmission accuracy thanks to sophisticated mechanical design and advanced manufacturing processes, the lack of an efficient closed-loop feedback system for joint angles will lead to significant motion deviations when faced with different loads or unstable power inputs. In actual control, they are difficult to be directly applied to various automation tasks like large-size robots.

[0004] At present, there are three main technical solutions for solving the joint angle perception of micro robots:

[0005] The first method is to press a section of snake-shaped constantan sheet into the SCM hinge, which senses the change in angle through the change in resistance of the metal layer during stretching or compression. However, constantan needs to ensure a sufficient bending radius when bending. Therefore, this solution needs to destroy the integrity of the SCM hinge in the process of integrating the sensor into the SCM hinge to leave enough deformation area for the sensor to avoid excessive stress and potential fracture of the material. The sensor is fixed at the left hinge and can slide freely in and out of the hollow layer reserved for the right hinge. In the area where constantan needs to bend, the wall teeth originally used to fix the hinge direction are deleted to allow constantan to deform. This may lead to the destruction of the overall stiffness of the micro-mechanism. At the same time, the fatigue characteristics of constantan sheets also doom this sensor to be unable to achieve long-term angle detection, and it is prone to fracture after a certain bending cycle.

[0006] The second solution is to glue strain gauges at the hinges, but this cannot be integrated with the SCM process and has the same bending radius and life issues as Constantan.

[0007] The third method is to print a micro-serpentine circuit on the central axis of the polyimide film of the SCM process. However, this solution is prone to breakage at a large bending angle and has poor sensing linearity. At the same time, this solution does not actually deploy the sensor on a micro-mechanism, but chooses to conduct related experiments in a scaled-up version of millidelta with a similar process. The performance of this solution in a micro-robot is unknown.

[0008] Therefore, how to achieve accurate and reliable angle self-perception without affecting the structural performance of the SCM hinge itself is a technical problem that needs to be solved urgently. Summary of the invention

[0009] The purpose of the present invention is to solve the above-mentioned technical problems in the prior art and to provide a SCM intelligent self-sensing joint hinge and method for a micro robot.

[0010] The specific technical solutions adopted by the present invention are as follows:

[0011] In a first aspect, the present invention provides a SCM intelligent self-sensing joint hinge for a micro robot, which includes a first carbon fiber board, a first bonding layer, a flexible circuit board, a second bonding layer, a second carbon fiber board, a wire and a transfer base;

[0012] The flexible circuit board uses a polyimide film as a substrate, and uses a single-side surface or a double-side surface of the substrate as an etching surface. Each etching surface is formed by laser etching into a microstructure etching pattern that is symmetrical with the hinge axis as the center line, and a series of metal electrodes are arranged around the edge of the microstructure etching pattern. Each metal electrode is connected to a transfer base for connecting an external circuit through a wire. The microstructure etching pattern on each etching surface and all metal electrodes are completely covered by a carbon nanotube film to form a piezoresistive thin film sensor.

[0013] The first carbon fiber board, the first adhesive layer, the flexible circuit board, the second adhesive layer and the second carbon fiber board are bonded in sequence to form a multi-layer composite joint hinge, and the first carbon fiber board and the second carbon fiber board are respectively disconnected at the hinge axis position, and each carbon fiber board is staggered and interlocked on both sides of the disconnection position through edge serrations, thereby limiting the translational freedom while maintaining the rotational freedom around the hinge axis.

[0014] As a preferred embodiment of the above-mentioned first aspect, the flexible circuit board is in the shape of an elongated strip as a whole, and is divided into two connecting rod parts by the hinge shaft, and the flexible circuit board has a convex part at the hinge shaft position, and the wires connected to all the metal electrodes on one of the connecting rod parts bypass the hinge shaft, and are routed through the convex part to converge on the other connecting rod part, and then are uniformly connected to the adapter base.

[0015] As a preferred embodiment of the first aspect, the carbon nanotube film is formed by coating a homogeneous conductive slurry of carbon nanotubes, carbon black and a resin binder on the surface of a substrate where microstructure etching patterns and metal electrodes are located and then curing the slurry. The thickness of the carbon nanotube film is in micrometer order.

[0016] As a preferred embodiment of the first aspect, the outer contour of the microstructure etching pattern is circular, and all metal electrodes are evenly distributed on the circular outer contour, and are paired in pairs to form electrode pairs for measuring resistance.

[0017] As a preferred embodiment of the first aspect, the outer contour of the microstructure etching pattern is circular, and staggered and parallel unetched rectangular strips are retained inside the circular outer contour area, and the remaining areas are formed into serpentine continuous grooves by laser ablation.

[0018] As a preferred embodiment of the first aspect, the long side direction of the unetched rectangular strip is perpendicular to the hinge axis.

[0019] As a preference of the first aspect above, the bonding material of the first bonding layer and the second bonding layer is adhesive, glue or hot-pressed adhesive tape.

[0020] In a second aspect, the present invention provides a method for manufacturing a SCM intelligent self-sensing joint hinge for a micro robot as described in any one of the solutions of the first aspect above, comprising:

[0021] S1. Locate the hinge axis on the surface of the polyimide film substrate of the flexible circuit board, and then use laser ablation technology to process a symmetrical microstructure etching pattern on the surface of the substrate with the hinge axis as the central symmetry line, and process a series of metal electrodes along the outer contour of the microstructure etching pattern, each of which is connected to a transfer base for connecting an external circuit through a wire;

[0022] S2, adding a homogeneous conductive slurry formed by fully mixing carbon nanotubes, carbon black and a resin binder into a container, and gradually transferring the homogeneous conductive slurry to the surface of the polyimide film substrate, so that the homogeneous conductive slurry completely covers the microstructure etching pattern and the metal electrode by a self-leveling film-forming method, and then solidifies to form a carbon nanotube film with uniform thickness;

[0023] S3. Stack the first carbon fiber board, the first adhesive layer, the flexible circuit board processed with a carbon nanotube film, a microstructure etching pattern and a metal electrode, the second adhesive layer and the second carbon fiber board in sequence, keep the serrated edge areas of the first carbon fiber board and the second carbon fiber board coincident with the hinge shaft position located on the flexible circuit board, and then hot-press and fix the stacked composite structure to form a multi-layer composite joint hinge.

[0024] As a preferred embodiment of the above-mentioned second aspect, the carbon nanotubes are functionally modified carbon nanotube materials, and the functional modification method is to uniformly disperse a mixed suspension of carbon nanotubes and carbon nanotube dispersants and then spray-dry; the carbon black is a functionally modified carbon black material, and the functional modification method is to disperse a mixed suspension of carbon black and carbon black dispersants through sand milling and then spray-dry.

[0025] As a preferred embodiment of the second aspect above, the preparation method of the homogeneous conductive slurry is: adding dipropylene glycol methyl ether to a cyclohexane solution of hydrogenated SBS powder, and then adding the functionalized carbon nanotube material, the functionalized carbon black material and the polyamide wax under stirring, and then transferring to a ball mill for ball milling to finally obtain a homogeneous conductive slurry.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] In response to the problems existing in the current micro self-sensing hinge, the present invention designs a piezoresistive film sensor that can be integrated into the SCM hinge. The sensor processes a microstructure etching pattern, a metal electrode and a carbon nanotube film on the polyimide film in the middle of the traditional SCM hinge, and uses the microstructure to maintain the surface of the polyimide film to form an anisotropic state, so that the polyimide film will produce a larger deformation amount with the bending of the hinge, and the carbon nanotube film coated and cured on the microstructure etching pattern will also produce cracks with correspondingly greater strength, thereby amplifying the impedance change that can be detected by the metal electrode and more accurately sensing the bending angle of the hinge. The carbon nanotube film prepared by this scheme is only a few microns thick, which will not have any effect on the SCM structure itself, and at the same time avoids the need to reserve deformation grooves in the SCM hinge. Since no additional components are required during the preparation process, this scheme facilitates the mass production of compact bending sensors, providing an efficient and accurate new solution for micro-robot joint angle sensing. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The decomposition structure diagram of the SCM intelligent self-sensing joint hinge for micro-robots;

[0029] Figure 2 The final morphology of the SCM intelligent self-sensing joint hinge for micro-robots;

[0030] Figure 3 Schematic diagram of the surface structure of the flexible circuit board in the SCM intelligent self-sensing joint hinge;

[0031] Figure 4 Schematic diagram of processing carbon nanotube film on flexible circuit board;

[0032] Figure 5 A schematic diagram for processing conductors and metal electrodes on a flexible circuit board;

[0033] Figure 6 A schematic diagram of processing microstructure etching patterns on a flexible circuit board;

[0034] Figure 7 Schematic diagram of processing carbon nanotube film on microstructure etched pattern;

[0035] Figure 8 Schematic diagram of the visual target in the bending state of the self-sensing joint hinge;

[0036] Fig. 9 It is the fitting result between the resistance value and the true value of the bending angle during the cyclic bending process in the embodiment of the present invention.

[0037] The reference numerals in the figure are: first carbon fiber board 1, first adhesive layer 2, flexible circuit board 3, second adhesive layer 4, second carbon fiber board 5, wire 6, adapter base 7, edge serration 8, metal electrode 9, protruding part 10, carbon nanotube film 11, microstructure etching pattern 12, visual target 13. DETAILED DESCRIPTION

[0038] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation mode of the present invention is described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. The technical features in each embodiment of the present invention can be combined accordingly without conflicting with each other.

[0039] In the description of the present invention, it is to be understood that when an element is considered to be "connected" to another element, it may be directly connected to the other element or indirectly connected, that is, there are intermediate elements. On the contrary, when an element is said to be "directly" connected to another element, there are no intermediate elements.

[0040] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for the purpose of distinguishing descriptions, and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features.

[0041] The SCM hinge is a hinge structure manufactured based on the SCM process. It is a carbon fiber-polyimide film-carbon fiber sandwich planar structure robot joint. The hinge structure can rotate around the axis of rotation and is an ideal choice for building micro robots. The core of the present invention is to design a piezoresistive film sensor that can be integrated into the SCM process. The sensor can be prepared on a large scale on a polyimide (PI) film. After integrating this piezoresistive film sensor into the traditional SCM hinge, the carbon nanotube film can be driven to crack through the microstructure prepared on the PI film, thereby accurately sensing the bending angle of the hinge. The carbon nanotube film prepared by this scheme is only a few microns thick, which will not have any effect on the SCM structure itself, and at the same time avoids the need to reserve deformation grooves in the SCM hinge. Moreover, since no additional components are required during the preparation process, this scheme facilitates the mass production of compact bending sensors, providing an efficient and accurate solution for micro robot joint angle sensing.

[0042] The specific implementation of the SCM intelligent self-sensing joint hinge for a micro robot of the present invention is described in detail below in conjunction with the accompanying drawings and embodiments.

[0043] In a preferred embodiment of the present invention, a SCM intelligent self-sensing joint hinge for a micro robot is provided, and the components of the SCM intelligent self-sensing joint hinge include a first carbon fiber board 1, a first adhesive layer 2, a flexible circuit board 3, a second adhesive layer 4, a second carbon fiber board 5, a wire 6 and a transfer base 7. The exploded structure diagram of the first carbon fiber board 1, the first adhesive layer 2, the flexible circuit board 3, the second adhesive layer 4, and the second carbon fiber board 5 is shown in FIG. Figure 1 As shown, the five-layer structure is stacked and compounded to form a multi-layer joint hinge in the form of SCM.

[0044] The core of the SCM intelligent self-sensing joint hinge to realize joint angle perception is the piezoresistive film sensor located on the flexible circuit board 3. The piezoresistive film sensor is composed of a microstructure etching pattern 12, a metal electrode 9, a wire 6 and a carbon nanotube film 11. For details, see Figure 2 As shown, the flexible circuit board 3 uses a polyimide film as a substrate, and the piezoresistive film sensor can be processed only on one side of the substrate, or on both sides. Therefore, in the embodiment of the present invention, during the processing of the flexible circuit board 3, it is necessary to first use one side or both sides of the polyimide film substrate as an etching surface, and each etching surface is formed by laser etching to form a microstructure etching pattern 12 that is symmetrical with the hinge axis as the center line, and a series of metal electrodes 9 are arranged around the edge of the microstructure etching pattern 12. Each metal electrode 9 is connected to a transfer base 7 for connecting an external circuit through a wire 6. See Figure 3As shown, after the microstructure etching pattern 12 and all the metal electrodes 9 are formed on each etching surface, a layer of carbon nanotube film 11 can be further formed on the microstructure etching pattern 12 and all the metal electrodes 9 by injecting a conductive paste containing carbon nanotubes. The range of the carbon nanotube film 11 needs to completely cover the microstructure etching pattern 12 and all the metal electrodes 9 surrounding the microstructure etching pattern 12. Thus, on each etching surface of the polyimide film substrate, the microstructure etching pattern 12, the metal electrode 9, the wire 6 and the carbon nanotube film 11 can constitute a piezoresistive thin film sensor.

[0045] The principle of the above-mentioned piezoresistive film sensor is that the microstructure etching pattern 12 made on the polyimide film substrate destroys the original uniformity of the film and forms an anisotropic surface morphology. Therefore, compared with the uniform film without microstructure processing, after the external force is applied to the sensor, the polyimide film processed with the microstructure etching pattern 12 will produce a larger deformation amount with the hinge bending, and the carbon nanotube film 11 coated and cured on the microstructure etching pattern 12 will also produce cracks with correspondingly greater strength. The resistance between each pair of metal electrodes 9 is directly related to the crack strength on the carbon nanotube film 11 between the two electrodes. Therefore, after processing the microstructure etching pattern 12, the sensor can sense a greater resistance change, and the external physical signal sensed will also be greater. Therefore, processing the microstructure etching pattern 12 in the hinge area where the polyimide film is deformed to destroy the isotropic state of the film can expand the angle sensing range of the sensor and improve its linearity.

[0046] In addition, the above-mentioned flexible circuit board 3 also needs to be processed based on the SCM process to form a planarized SCM joint hinge. The specific method is to sequentially bond the first carbon fiber board 1, the first adhesive layer 2, the flexible circuit board 3, the second adhesive layer 4 and the second carbon fiber board 5 to form a multi-layer composite joint hinge, wherein the first adhesive layer 2 is used to bond the first carbon fiber board 1 and the flexible circuit board 3, and the second adhesive layer 4 is used to bond the flexible circuit board 3 and the second carbon fiber board 5. Moreover, in order to ensure that the rotational actuation function of the hinge can be realized normally, the first carbon fiber board 1 needs to be disconnected at the hinge shaft position, and edge serrations 8 need to be processed on both sides of the disconnection position, and then the two parts of the carbon fiber board disconnected at the hinge shaft position need to be kept in an interlaced state through the edge serrations 8, so as to limit the two parts of the carbon fiber board from having no translational freedom while maintaining the first carbon fiber board 1 as a whole having rotational freedom around the hinge shaft. Similarly, the second carbon fiber board 5 also needs to be disconnected at the hinge axis position, and edge serrations 8 are formed on both sides of the disconnected position. The two carbon fiber boards disconnected at the hinge axis position need to be kept in an interlaced state through the edge serrations 8, so as to limit the two carbon fiber boards from having no translational freedom while maintaining the second carbon fiber board 5 as a whole having rotational freedom around the hinge axis. The SCM intelligent self-sensing joint hinge finally formed by processing is as follows: Figure 4 The edge serrations 8 in this embodiment are in the form of wall teeth.

[0047] It should be noted that, no matter the first carbon fiber board 1 or the second carbon fiber board 5, its translational freedom is limited by the staggered interlocking state of the edge serrations 8 and the flexible circuit board 3. That is, for each carbon fiber board, the two parts of the carbon fiber board disconnected along the hinge axis are both bonded and fixed to the flexible circuit board 3, so they cannot be separated from each other in the direction perpendicular to the hinge axis. At the same time, because the two parts are kept in a staggered interlocking state by the edge serrations 8, they cannot translate relative to each other in the direction parallel to the hinge axis.

[0048] In addition, in the embodiment of the present invention, the flexible circuit board 3 is in the shape of a long strip as a whole, and the specific shape can be designed according to the actual hinge shape. The long strip flexible circuit board 3 is divided into two connecting rod parts by the hinge shaft. Figure 5As shown, the wires 6 connected to all the metal electrodes 9 located on one of the connecting rod parts need to bypass the hinge shaft, and converge to the other connecting rod part through the convex part 10, and then be uniformly connected to the adapter base 7. This approach can ensure that the wire 6 will not directly pass through the hinge shaft, avoid the disconnection of the wire 6 during the reciprocating movement of the hinge, and improve the life of the hinge. At the same time, in theory, the processing of the microstructure etching pattern 12, the wire 6 and the metal electrode 9 can be replaced according to actual needs. It is possible to process the microstructure etching pattern 12 first and then the metal electrode 9 and the wire 6, or to process the metal electrode 9 and the wire 6 first and then the microstructure etching pattern 12. Therefore, when the latter processing sequence is selected, after the metal electrode 9 and the wire 6 are processed first, since the wire 6 will not directly pass through the hinge shaft but will be routed through the convex part 10, the wire 6 will not be damaged during the laser ablation process.

[0049] It should be noted that the adapter base 7 in the present invention can be any component that can be connected to an external signal acquisition device or circuit. In the embodiment of the present invention, the adapter base 7 in the form of a gold finger can be used in accordance with the practice of traditional SCM hinges.

[0050] It should be noted that the carbon nanotube film 11 can theoretically be any carbon nanotube film with high conductivity and cracks during deformation, and its formula can be adjusted according to actual needs. In the embodiment of the present invention, carbon nanotubes, carbon black and resin binder are mixed to form a homogeneous conductive paste. After the homogeneous conductive paste is prepared, the homogeneous conductive paste is applied to the surface of the substrate where the microstructure etching pattern 12 and the metal electrode 9 are located, and then the whole is heated and cured at a temperature that does not damage the performance of the substrate to form a layer of carbon nanotube film 11. The thickness of the carbon nanotube film 11 should be uniform, and the specific thickness can be optimized and adjusted according to actual conditions, and is generally preferably in the micrometer level.

[0051] It should be noted that the form of the microstructure etching pattern 12 in the present invention is theoretically not limited, as long as it can destroy the isotropic state of the film and amplify the deformation of the polyimide film caused by the bending of the hinge.

[0052] In an embodiment of the present invention, an optimized microstructure etching pattern 12 is designed. The outer contour of the microstructure etching pattern 12 is circular, and all metal electrodes 9 are evenly distributed on the circular outer contour, so that they can be paired in pairs to form electrode pairs for measuring the resistance between electrodes. Designing the microstructure etching pattern 12 to be approximately circular can ensure that all metal electrodes 9 can be distributed more evenly, so that the detected resistance value can be better used for modeling and predicting the joint angle of the hinge.

[0053] See also Figure 6As shown, in the embodiment of the present invention, the etching pattern form inside the circular outer contour is also optimized. Inside the circular outer contour area of ​​the microstructure etching pattern 12, a series of staggered and parallel unetched rectangular strips are retained, and the remaining areas are formed into continuous grooves with serpentine bends by laser ablation. Figure 6 The white area in the middle is the unetched area, and the black area is the groove formed by laser ablation. These grooves are continuous. Except for the position close to the circular outer contour, the rest of the groove parts are straight strips. All straight strip grooves are also parallel and equidistant. Two adjacent straight strip grooves are connected by an approximate arc segment, so that all the grooves continuously form a serpentine bending pattern.

[0054] In addition to the pattern shape, in the embodiment of the present invention, the direction of the microstructure etching pattern 12 is also optimized. Figure 6 As shown, in the final microstructure etching pattern 12, the long side direction of the unetched rectangular strip is perpendicular to the hinge axis of the joint hinge. Compared with the unetched rectangular strip being parallel to the hinge axis and the unetched rectangular strip being obliquely intersecting with the hinge axis, the microstructure etching pattern 12 is in a posture where the unetched rectangular strip is perpendicular to the hinge axis, which can significantly increase the range and improve the linearity between the inter-electrode resistance and the actual rotation angle.

[0055] It should be noted that the first bonding layer 2 and the second bonding layer 4 in the present invention are mainly used to bond the first carbon fiber board 1, the flexible circuit board 3, and the second carbon fiber board 5, and also play an insulating role to prevent the carbon nanotube film from short-circuiting. Therefore, in theory, the bonding material can be any material that can achieve the bonding function, such as viscose, glue or hot pressing tape. In an embodiment of the present invention, the entire SCM intelligent self-sensing joint hinge can be realized by a hot pressing process after the 5-layer structure is superimposed, so the first bonding layer 2 and the second bonding layer 4 can be made of hot pressing tape.

[0056] It should be noted that in the above-mentioned piezoresistive thin film sensor of the present invention, all the metal electrodes 9 surrounding the microstructure etching pattern 12 are the core elements for detecting the resistance. Theoretically, any two of the metal electrodes 9 can be paired to detect the corresponding resistance value between them. The specific number of metal electrodes 9 can be optimized as needed. Figure 5In the illustrated embodiment, four metal electrodes 9 are arranged around the microstructure etching pattern 12, but this is merely an exemplary approach in the embodiment of the present invention, and more metal electrodes 9 may also be used. Since any two metal electrodes 9 in the piezoresistive film sensor can output a resistance detection value, how to use the multiple resistance detection values ​​output by the piezoresistive film sensor to estimate the rotation angle of the joint hinge requires the use of a corresponding detection algorithm to achieve this. In an embodiment of the present invention, a rotation angle estimation model can be constructed using a linear model, a nonlinear model, a machine learning algorithm, and a neural network. The model input is a plurality of resistance detection values ​​output by the piezoresistive film sensor, and the output is the rotation angle of the joint hinge. However, it should be noted that the rotation angle estimation model is not a component of the SCM intelligent self-sensing joint hinge, but is a back-end module that further processes the sensor data in the SCM intelligent self-sensing joint hinge.

[0057] In addition, in an embodiment of the present invention, a method for manufacturing the above-mentioned SCM intelligent self-sensing joint hinge for a micro robot is also provided, which comprises:

[0058] S1, locating the hinge axis position on the surface of the polyimide film substrate of the flexible circuit board 3, and then processing a symmetrical microstructure etching pattern 12 on the surface of the substrate by laser ablation technology with the hinge axis as the central symmetry line, and processing a series of metal electrodes 9 along the outer contour of the microstructure etching pattern 12, each metal electrode 9 is connected to the adapter base 7 for connecting to an external circuit through a wire 6;

[0059] S2, adding a homogeneous conductive slurry formed by fully mixing carbon nanotubes, carbon black and a resin binder into a container, and gradually transferring the homogeneous conductive slurry to the surface of the polyimide film substrate, so that the homogeneous conductive slurry completely covers the microstructure etching pattern 12 and the metal electrode 9 by a self-leveling film-forming method, and then heating and curing to form a carbon nanotube film 11 with uniform thickness;

[0060] S3. Stack the first carbon fiber board 1, the first adhesive layer 2, the flexible circuit board 3 processed with a carbon nanotube film 11, a microstructure etching pattern 12 and a metal electrode 9, the second adhesive layer 4, and the second carbon fiber board 5 in sequence, keep the edge serrations 8 of the first carbon fiber board 1 and the second carbon fiber board 5 interlaced with the hinge axis located on the flexible circuit board 3, and then hot-press the stacked composite structure to form a multi-layer composite joint hinge.

[0061] It should be noted that the above-mentioned carbon nanotubes, carbon black and resin binder can be commercially available materials, as long as they can form a carbon nanotube film 11 that meets the requirements. In an embodiment of the present invention, the carbon nanotubes preferably use functionally modified carbon nanotube materials, and the functional modification method is to homogenously disperse the mixed suspension of carbon nanotubes and carbon nanotube dispersants and then spray dry them. Carbon black preferably uses functionally modified carbon black materials, and the functional modification method is to disperse the mixed suspension of carbon black and carbon black dispersants through sand milling and then spray dry them. Therefore, the preparation method of the above-mentioned homogeneous conductive slurry is preferably as follows: dipropylene glycol methyl ether is added to the cyclohexane solution of hydrogenated SBS powder, and then the functionally modified carbon nanotube material, the functionally modified carbon black material and polyamide wax are added under stirring, and then transferred to a ball mill for ball milling, and finally a homogeneous conductive slurry is obtained.

[0062] Therefore, the above manufacturing method can be integrated into the SCM manufacturing process of the self-sensing hinge without loss, so that the self-sensing hinge can be mass-produced. Through the present invention, a high-performance angle sensor can be integrated into the SCM process, providing a new high-precision joint posture sensing solution for micro robots.

[0063] The following is a specific example to demonstrate the manufacturing method of the SCM intelligent self-sensing joint hinge for a micro robot. At the same time, the prepared SCM intelligent self-sensing joint hinge is subjected to a performance test on an actual micro mechanism to verify the performance of the present invention.

[0064] Example

[0065] In this embodiment, the chemical reagents used in the manufacturing process are all commercially available products of analytical grade, among which: cyclohexane and dipropylene glycol methyl ether are from Shanghai MacLean Biochemical Technology Co., Ltd., carbon nanotube powder is from Shenzhen Nanoport Co., Ltd., carbon black powder is from Cabot, carbon nanotube dispersant and carbon black dispersant are from Jiangsu Zhaohuang New Energy Technology Co., Ltd., polyamide wax is from Nanjing Tianshi Wax Powder Co., Ltd., and hydrogenated SBS powder (SEBS) is from Sinopec Baling Petrochemical Branch.

[0066] In this embodiment, the manufacturing method of the SCM intelligent self-sensing joint hinge has the following steps:

[0067] 1. Functionalization of carbon materials

[0068] 12.5g of carbon nanotube dispersant was added to 937.5g of deionized water and stirred for 30min to obtain a dark brown solution. During the stirring process, 50g of carbon nanotubes were added to the dark brown solution and stirred vigorously for 30min to obtain a black suspension. The black suspension was then homogenized and dispersed in a homogenizer at 800bar for 30min to obtain a uniformly dispersed black solution. The black solution was then spray dried and a black powder was collected to obtain the functionally modified carbon nanotube material.

[0069] In addition, 50g of carbon black dispersant was added to 850g of deionized water and stirred for 30min to obtain a yellow solution. During the stirring process, 100g of carbon black was added to the yellow solution and stirred vigorously for 30min to obtain a black suspension. The black suspension was then dispersed by sand milling at 1500r / min for 30min to obtain a uniformly dispersed black solution. The black solution was then spray dried and collected to obtain a black powder, which was the functionally modified carbon black material.

[0070] 2. Preparation of resin solution

[0071] During the stirring process, 20 g of SEBS was dispersed into 400 ml of cyclohexane, dissolved by stirring in a water bath at 60° C. for 120 min, and then transferred to ultrasonic dispersion for 120 min to obtain a SEBS solution.

[0072] 3. Preparation of carbon film conductive slurry

[0073] 2g of dipropylene glycol methyl ether was added to 200g of the above SEBS solution, and then 5.5g of the functionalized carbon black material, 2g of the functionalized carbon nanotube material and 0.2g of polyamide wax were added under stirring, and then vigorously stirred for 20min. After stirring, the mixture was transferred to a ball mill and ball milled at 500r / min for 720min to obtain a homogeneous carbon film conductive slurry.

[0074] 4. Laser ablation of metal electrodes and microstructures

[0075] On the polyimide (PI) film produced by the SCM process, according to the design position of the hinge shaft, the preset position of the hinge shaft is located on the surface of the PI film, and the circular outer contour of the microstructure etching pattern 12 to be etched is determined. Then, four metal electrodes 9 are processed along the circular outer contour of the microstructure etching pattern 12 to be etched at equal central angles, with two on the left side of the hinge shaft and two on the right side of the hinge shaft, and arranged symmetrically. Figure 5As shown, the wires 6 connected to the two electrodes on the left side of the hinge shaft need to be routed through the convex part 10, and then gathered to the connecting rod part on the right side of the hinge shaft, and connected in parallel with the wires 6 connected to the two electrodes on the right side to the gold finger as the adapter base 7. The wires 6 are made of 75 micron thick FPC flexible circuit board wires. Then, laser ablation technology is used to create a microstructure etching pattern 12 on the PI film. The circular outer contour of the microstructure etching pattern 12 just connects with the four metal electrodes 9, as shown in FIG. Figure 6 As shown, the outer contour of the microstructure etching pattern 12 is circular, and there are staggered and parallel unetched rectangular strips inside the circular outer contour area. The rest of the area is formed into a continuous groove with a serpentine bend by laser ablation, and the long side direction of the unetched rectangular strip is perpendicular to the hinge axis. These microstructure etching patterns are located in the area where the film will deform, the purpose is to increase the deformation of the PI film when the hinge is bent, thereby expanding the angle sensing range of the sensor and improving its linearity. In this embodiment, the microstructure etching pattern 12 and the metal electrode 9 are finally processed only on one side of the PI film, and the resulting flexible circuit board 3 is as shown in FIG. Figure 3 shown.

[0076] 5. Carbon nanotube film coating

[0077] The prepared carbon film conductive slurry is evenly coated on Figure 3 The specific method is as follows: use a pipette to transfer 15 microliters of carbon film conductive paste, and place the PI film on a flat metal plate with the microstructure etching pattern 12 facing upward, and the surface temperature of the metal plate is controlled below 10°C. Figure 7 As shown, the carbon film conductive slurry is dripped onto the center of the microstructure etched pattern 12, and allowed to self-level at low temperature (≤10°C) to form a film covering the microstructure etched pattern 12 and the four metal electrodes 9, and then transferred to an 80°C oven and heated and cured for 30 minutes to form a conductive carbon nanotube film 11. This step Figure 3 The flexible circuit board 3 shown is processed into Figure 4 The flexible circuit board 3 shown is the key to preparing the sensor, which can ensure the conductivity and sensitivity of the sensor.

[0078] 2.7 Assembly of the Self-Sensing Hinge

[0079] Finally, the prepared Figure 4 The flexible circuit board 3 shown is used as the middle layer, and the first carbon fiber board 1 (CF 500 microns) and the second carbon fiber board 5 (CF 500 microns) pre-processed according to the SCM process and provided with edge serrations 8 are used, and the hot pressing tape (model FR1500, DuPont) is used as the first bonding layer 2 and the second bonding layer 4. Figure 1In the order shown, the first carbon fiber board 1, the first adhesive layer 2, the flexible circuit board 3, the second adhesive layer 4, and the second carbon fiber board 5 are stacked from top to bottom in sequence; during the stacking process, the interlaced area of ​​the edge serrations 8 on the first carbon fiber board 1 and the second carbon fiber board 5 must coincide with the hinge axis position located on the flexible circuit board 3. Then, the stacked structure is hot-pressed according to the SCM process, so that the flexible circuit board 3 is bonded and fixed between the two layers of carbon fiber boards, completing the preparation of the self-sensing hinge, and the final external shape is as follows Figure 2 This design allows the hinge to accurately sense and feedback angle changes when it bends, achieving high-precision angle sensing.

[0080] It should be noted that, in order to facilitate testing, Figure 5 Two mounting holes are respectively opened on both sides of the hinge shaft in the layer structure to facilitate connection with an external driving mechanism.

[0081] In this embodiment, the performance of the prepared SCM intelligent self-sensing joint hinge (referred to as the hinge of this embodiment) is tested. The specific test method is: the gold finger of the processed self-sensing joint hinge is plugged into the detection circuit, and the detection circuit detects the resistance value between the two metal electrodes in the piezoresistive film sensor of the joint hinge during the bending process, and at the same time, the visual target 13 is set on the joint hinge to record the actual bending angle of the joint hinge. Figure 8 As shown, the visual target 13 can be set on the side of the hinge in the form of a straight mark. When the hinge is bent, the mark in the original straight form also bends. The corresponding rotation angle can be measured after shooting by an imaging device as the true value of the actual angle signal. In this embodiment, the detection data is recorded once every 30 bending cycles, and the sensor is bent 450 times in total. Finally, after the obtained detection data is matched, the detected resistance value is fitted with the actual bending angle of the recorded joint hinge. The experimental results show that the hinge of this embodiment is bent from -60° to +60° and then to -60°, and can maintain a high stability in 450 bending cycles. Fig. 9 The figure shows the fitting between the resistance value (in Ω) and the actual bending angle (in °) in 15 bending cycles. It can be seen that the resistance value output by the piezoresistive film sensor during the hinge bending process of the present invention can accurately reflect the actual bending angle, and the two have good linearity.

[0082] At the same time, several other comparative self-sensing hinges are also processed in this embodiment, and the difference between them and the hinge of this embodiment is only in the pattern and direction of the microstructure etching pattern 12. Figure 6 The microstructure etched pattern 12 shown is rotated 90° so that the unetched rectangular strip is parallel to the hinge axis; the second comparison self-sensing hinge will Figure 6The microstructure etched pattern 12 shown is rotated 45° so that the unetched rectangular strip intersects the hinge axis at an angle. Figure 6 The microstructure etching pattern 12 shown is changed to a circular etching groove arranged in concentric circles. The performance test results show that the linearity between the resistance value output by the sensor and the actual angle true value of the first comparison self-sensing hinge is extremely poor, and the two are exponential rather than linear; the angle range of the second comparison self-sensing hinge is only about 1 / 3 of the hinge of this embodiment, and the linearity between the resistance value output by the sensor and the actual angle true value also decreases significantly; the angle range and linearity of the third comparison self-sensing hinge are also obviously inferior to the hinge of this embodiment.

[0083] It can be seen that the SCM intelligent self-sensing joint hinge with a piezoresistive film sensor prepared by the present invention can realize the angle signal output of the hinge, and has the advantages of high linearity, long life, and wider sensing range. Moreover, the carbon nanotube film prepared on the polyimide film in this solution is only a few microns thick and will not affect the SCM structure itself. Therefore, this sensor can be perfectly integrated and embedded in the SCM hinge without destroying the structure of the SCM hinge itself.

[0084] The above-described embodiments are only some preferred implementations of the present invention, but are not intended to limit the present invention. A person skilled in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. A SCM intelligent self-sensing joint hinge for a micro robot, characterized in that: It comprises a first carbon fiber board (1), a first adhesive layer (2), a flexible circuit board (3), a second adhesive layer (4), a second carbon fiber board (5), a wire (6) and a transfer base (7); The flexible circuit board (3) uses a polyimide film as a substrate, and uses a single-side surface or a double-side surface of the substrate as an etching surface. Each etching surface is formed by laser etching into a microstructure etching pattern (12) that is symmetrical with the hinge axis as the center line, and a series of metal electrodes (9) are arranged around the edge of the microstructure etching pattern (12). Each metal electrode (9) is connected to a transfer base (7) for connecting to an external circuit through a wire (6). The microstructure etching pattern (12) on each etching surface and all metal electrodes (9) are completely covered by a carbon nanotube film (11), forming a piezoresistive thin film sensor. The first carbon fiber board (1), the first adhesive layer (2), the flexible circuit board (3), the second adhesive layer (4) and the second carbon fiber board (5) are sequentially bonded to form a multi-layer composite joint hinge, and the first carbon fiber board (1) and the second carbon fiber board (5) are respectively disconnected at the hinge axis position, and each carbon fiber board is staggered and interlocked at both sides of the disconnection position through edge serrations (8), thereby limiting the translational freedom while maintaining the rotational freedom around the hinge axis.

2. The SCM intelligent self-sensing joint hinge for a micro robot as claimed in claim 1, characterized in that: The flexible circuit board (3) is in the shape of an elongated strip as a whole and is divided into two connecting rod parts with the hinge shaft as the boundary. The flexible circuit board (3) has a convex part (10) at the hinge shaft position. The wires (6) connected to all the metal electrodes (9) located on one of the connecting rod parts bypass the hinge shaft and are routed through the convex part (10) to converge on the other connecting rod part and are then uniformly connected to the adapter base (7).

3. The SCM intelligent self-sensing joint hinge for a micro robot as claimed in claim 1, characterized in that: The carbon nanotube film (11) is formed by coating a homogeneous conductive slurry formed by mixing carbon nanotubes, carbon black and a resin binder on the surface of a substrate where a microstructure etching pattern (12) and a metal electrode (9) are located and then curing the resulting film. The thickness of the carbon nanotube film (11) is in the micrometer order.

4. The SCM intelligent self-sensing joint hinge for a micro robot as claimed in claim 1, characterized in that: The outer contour of the microstructure etching pattern (12) is circular, and all metal electrodes (9) are evenly distributed on the circular outer contour and are paired in pairs to form electrode pairs for measuring resistance.

5. The SCM intelligent self-sensing joint hinge for a micro robot as claimed in claim 1, characterized in that: The outer contour of the microstructure etching pattern (12) is circular, and staggered and parallel unetched rectangular strips are retained inside the circular outer contour area, and the remaining areas are formed into serpentine continuous grooves through laser ablation.

6. The SCM intelligent self-sensing joint hinge for a micro robot as claimed in claim 5, characterized in that: The long side direction of the unetched rectangular strip is perpendicular to the hinge axis.

7. The SCM intelligent self-sensing joint hinge for a micro robot as claimed in claim 1, characterized in that: The bonding material of the first bonding layer (2) and the second bonding layer (4) is adhesive, glue or hot-pressed adhesive tape.

8. A method for manufacturing a SCM intelligent self-sensing joint hinge for a micro robot as claimed in any one of claims 1 to 7, characterized in that: include: S1, locating the hinge axis position on the surface of the polyimide film substrate of the flexible circuit board (3), then processing a symmetrical microstructure etching pattern (12) on the surface of the substrate with the hinge axis as the central symmetry line by laser ablation technology, and processing a series of metal electrodes (9) along the outer contour of the microstructure etching pattern (12), each metal electrode (9) is connected to a transfer base (7) for connecting to an external circuit through a wire (6); S2, adding a homogeneous conductive slurry formed by fully mixing carbon nanotubes, carbon black and a resin binder into a container, and gradually transferring the homogeneous conductive slurry to the surface of the polyimide film substrate, so that the homogeneous conductive slurry completely covers the microstructure etching pattern (12) and the metal electrode (9) by a self-leveling film-forming method, and then solidifies to form a carbon nanotube film (11) with uniform thickness; S3, stacking the first carbon fiber board (1), the first adhesive layer (2), the flexible circuit board (3) processed with a carbon nanotube film (11), a microstructure etching pattern (12) and a metal electrode (9), the second adhesive layer (4), and the second carbon fiber board (5) in sequence, keeping the staggered area of ​​the edge serrations (8) of the first carbon fiber board (1) and the second carbon fiber board (5) coincident with the hinge axis position located on the flexible circuit board (3), and then hot pressing the stacked composite structure to form a multi-layer composite joint hinge.

9. The manufacturing method according to claim 8, characterized in that: The carbon nanotubes are functionally modified carbon nanotube materials, and the functional modification method is to uniformly disperse a mixed suspension of carbon nanotubes and carbon nanotube dispersants and then spray-dry; the carbon black is a functionally modified carbon black material, and the functional modification method is to disperse a mixed suspension of carbon black and carbon black dispersants through sand milling and then spray-dry.

10. The manufacturing method according to claim 9, characterized in that: The preparation method of the homogeneous conductive slurry is as follows: dipropylene glycol methyl ether is added to a cyclohexane solution of hydrogenated SBS powder, and then a functionally modified carbon nanotube material, a functionally modified carbon black material and polyamide wax are added under stirring, and then the mixture is transferred to a ball mill for ball milling, so as to finally obtain a homogeneous conductive slurry.

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