A high-precision sliding information sensing tactile patch and sensing method

Abstract

The application provides a high-precision sliding information sensing sliding tactile sensor patch, a sliding information sensing method and a preparation method. The sliding tactile sensor patch adopts a ladder-shaped electrode design, which comprises fixedly and spacedly arranged rectangular electrodes; the widths of the rectangular electrodes are consistent, and the lengths are arranged in an arithmetic progression; the signal output by the signal detection end of the ladder-shaped electrode is a periodic oscillation signal, the oscillation frequency represents the sliding speed of a sliding object, the oscillation number of the oscillation signal represents the sliding displacement of the sliding object, and the positive and negative of the low-frequency signal of the oscillation signal represents the sliding direction of the sliding object. It can be seen that the ladder-shaped electrode can encode and retain the sliding speed, sliding direction and sliding displacement information generated in the sliding process, and the sliding information can be decoupled and restored in subsequent processing; compared with the limitation that the traditional sliding tactile sensor can only detect whether sliding occurs, the sliding information detected by the sensor has higher dimensions, which is helpful for the intelligent gripper to accurately judge the gripping state.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, specifically to a tactile sensor patch for monitoring the sliding and pressure information generated by an object during grasping in a biomimetic intelligent gripper, its preparation method, and the sliding information sensing method. Background Technology

[0002] With the rapid development of robotics and the demand for virtual interaction, people's requirements for the accuracy of tactile perception and natural interactive experience are increasing. Traditional tactile sensing methods, such as pressure sensing, vibration feedback, and contact separation detection, are no longer sufficient to meet the high-resolution perception requirements for complex sliding behaviors, fine material identification, and dynamic interaction processes. Against this backdrop, flexible tactile sensors—also known as electronic skin—have become an important carrier for mimicking the functions of biological skin due to their thinness, high flexibility, high sensitivity, and ability to closely conform to complex curved surfaces, showing broad prospects in fields such as human-computer interaction, dexterous robot operation, and wearable health monitoring.

[0003] Currently, research on flexible tactile sensors mainly focuses on capturing static or quasi-static mechanical signals, such as improving the sensing performance of normal pressure through microstructure design and new material composites. However, during dynamic sliding, it is often difficult to synchronously and accurately decouple multi-dimensional motion information such as sliding speed, direction, and displacement, limiting its application depth in fine manipulation and simulated interaction.

[0004] In intelligent grasping scenarios, especially during the process of intelligent robotic arms grasping and moving objects, objects are prone to slipping. In such cases, traditional rigid slip sensors are often bulky and are typically manufactured to the same specifications as the robotic gripper, resulting in poor versatility. Flexible slip sensors, which can be flexibly attached to various object surfaces, can only detect whether slippage occurs. They struggle to synchronously and accurately decouple multi-dimensional motion information such as slippage speed, direction, and displacement, failing to provide a reference for adjusting the movement and grasping parameters of the intelligent gripper and limiting their application depth in precision control and realistic interaction. Summary of the Invention

[0005] In view of this, the present invention provides a high-precision sliding information sensing patch for tactile sensing, which can be flexibly attached to the surface of various objects, and can accurately detect the sliding speed, sliding direction and displacement of objects on the sensor surface during sliding. It has a simple structure and is feasible.

[0006] To solve the above-mentioned technical problems, the present invention is implemented as follows.

[0007] A high-precision sliding information sensing patch for tactile sensing includes a triboelectric nanogenerator (TENG) sliding sensor assembly.

[0008] The TENG sliding sensor assembly includes an electronegative thin film, a stepped electrode, and a first substrate stacked from top to bottom; The stepped electrode includes a comb structure consisting of rectangular electrodes arranged at intervals and connecting bridges connecting each rectangular electrode at one end; the rectangular electrodes have a uniform width, fixed intervals, and lengths arranged in an arithmetic sequence. A stepped electrode leads out to a signal detection terminal for connecting to a signal detection device; The signal output by the stepped electrode signal detection terminal is a periodic oscillation signal. The oscillation frequency of the oscillation signal expresses the sliding speed of the sliding object, the number of oscillations of the oscillation signal expresses the sliding displacement of the sliding object, and the positive or negative sign of the low-frequency signal of the oscillation signal expresses the sliding direction of the sliding object.

[0009] Preferably, the stepped electrode is composed of a pair of identical comb structures arranged tooth-to-tooth to form a centrally symmetrical structure; one of the two comb structures leads out a signal detection terminal and is connected to the positive terminal of the detection device, and the other leads out a signal reference terminal and is connected to the negative terminal of the detection device.

[0010] Preferably, in the stepped electrodes, the rectangular electrodes have a width of 2 mm, a spacing of 1 mm, and an electrode length ranging from 18 mm to 1 mm, arranged in an arithmetic progression with a difference of 1 mm.

[0011] Preferably, the electronegative material used in the electronegative film is fluorinated ethylene propylene copolymer (FEP), polytetrafluoroethylene (PTFE), or silicone rubber.

[0012] Preferably, the tactile sensor patch further includes a piezoresistive pressure sensor assembly, which consists of a second substrate, interdigitated electrodes, a piezoresistive sheet, an adhesive material, and a flexible buffer layer connected in sequence; the second substrate is interconnected with the first substrate.

[0013] Preferably, the second substrate and the first substrate are the same substrate, and stepped electrodes and interdigitated electrodes are respectively fabricated on the positive and negative sides.

[0014] Preferably, the interdigitated electrodes are spaced 1 mm apart; the adhesive material is fluorinated ethylene propylene copolymer (FEP); and the flexible buffer layer material is Ecoflex silicone rubber.

[0015] Preferably, the substrate material is polyimide (PI).

[0016] The present invention also provides a sliding information sensing method, which uses the above-mentioned high-precision sliding information sensing tactile sensor patch, the method comprising: Perform a Fourier transform on the oscillation signal output from the stepped electrode signal detection terminal to extract the frequency f corresponding to the highest frequency peak in the spectrum signal; Multiplying the frequency f by the period of the rectangular electrode arrangement yields the sliding speed of the sliding object. Based on the peaks and / or troughs, count the number of oscillations of the oscillation signal, multiply it by the period of the rectangular electrode arrangement, and obtain the sliding displacement; The oscillation signal is low-pass filtered, and the low-frequency signal obtained is integrated to determine its sign, which corresponds to the sign of the sliding direction.

[0017] The present invention further provides a method for preparing the above-mentioned high-precision sliding information sensing patch, comprising: Step 1: Stepped electrodes and interdigitated electrodes are fabricated on both sides of the common substrate of the TENG sliding sensor assembly and the piezoresistive pressure sensor assembly using a template copper plating process; Step 2: Attach the electronegative thin film to the prepared stepped electrode side; Step 3: Laser cut the varistor sheet to the designed size, use adhesive material to attach it to the prepared interdigitated electrode side, then apply the material of the flexible buffer layer to the pressure sensing side of the varistor sheet, cure it at the specified temperature, remove the excess part of the flexible buffer layer material, and obtain the tactile sensing patch.

[0018] Beneficial effects: (1) The present invention adopts a stepped electrode structure design, which can encode and retain the sliding speed, sliding direction and sliding displacement information generated during the sliding process, and decouple and restore the sliding information in subsequent processing; compared with the limitation of traditional tactile sensors that can only detect whether sliding occurs, the sliding information detected by this sensor has a higher dimension, which helps the intelligent gripper to accurately judge the gripping state and provides a guarantee for the safety of the robot hand when grasping the object.

[0019] (2) The present invention has a simple structure. The device prepared based on this structure is lightweight and compact. It can be attached to any rigid or flexible machine gripper to accurately sense the sliding information during the gripping process and can be applied in most application scenarios.

[0020] (3) In a preferred embodiment, two stepped electrodes arranged in a tooth-to-tooth configuration are used to form a centrally symmetrical structure, which changes the signal amplitude from the length of a single electrode to the area difference between the two electrodes, effectively improving the signal amplitude generated by the device within a limited area, improving the signal-to-noise ratio of the detection signal in extreme cases (when the slider slides to the end), and improving the accuracy of sensing sliding information.

[0021] (4) The present invention is based on the sliding direction, sliding displacement and sliding speed calculation method of the detection signal. The calculation is simple. Specifically, the signal will oscillate once every time the object slides over a physical combination of an electrode / gap on the surface of the device. Therefore, the speed can be calculated by the characteristic frequency f of the signal oscillation (v=f*L, where L is the length of the electrode / gap); the sliding displacement can be obtained by counting the peaks and valleys (D=N*L, where N is the number of peaks); the sliding direction information is hidden in the low frequency of the signal. By low-pass filtering and integrating the low frequency signal, its positive or negative sign can be obtained, which corresponds to the sliding direction.

[0022] (5) In a preferred embodiment, the tactile sensor patch of the present invention also integrates a piezoresistive pressure sensor assembly, which detects the sliding information and senses the magnitude of the pressure applied during the gripping of the object. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the tactile sensor patch in Embodiment 1 of the present invention.

[0024] Figure 2 This is a schematic diagram of the stepped electrode in Embodiment 1 of the present invention.

[0025] Figure 3 This is a schematic diagram of the stepped electrode in Embodiment 2 of the present invention.

[0026] Figure 4 This is a schematic diagram of the detection signal in Embodiment 2 of the present invention.

[0027] Figure 5 This is a schematic diagram of the tactile sensor patch in Embodiment 3 of the present invention.

[0028] Figure 6 This is a schematic diagram of the finger electrode in Embodiment 3 of the present invention. Detailed Implementation

[0029] This invention provides a high-precision sliding information sensing patch for tactile sensing. The basic idea is to design a triboelectric nanogenerator (TENG) sliding sensor assembly mainly composed of an electronegative thin film and a stepped electrode. When an object slides across the surface, the stepped electrode generates a periodic oscillation signal. The oscillation frequency of the signal expresses the sliding speed of the object, and the number of oscillations expresses the sliding displacement of the object. The positive or negative sign of the low-frequency signal of the oscillation indicates the sliding direction of the object, thereby realizing the detection of the sliding speed, sliding direction, and displacement magnitude of the object on the sensor surface during the sliding process.

[0030] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] Example 1 Figure 1 This is a structural diagram of a high-precision sliding information sensing patch according to Embodiment 1 of the present invention. As shown in the figure, the sliding tactile sensing patch includes an electronegative thin film 1, a stepped electrode 2, and a first substrate 3 stacked sequentially from top to bottom. This electronegative thin film + electrode structure is called a triboelectric nanogenerator (TENG) sliding sensor assembly.

[0032] like Figure 2 As shown, this embodiment designs a special stepped electrode 2 structure, which is a comb structure composed of rectangular electrodes arranged at intervals and connecting bridges connecting the rectangular electrodes at one end. The rectangular electrodes have a uniform width, fixed intervals, and lengths arranged in an arithmetic sequence. The stepped electrode 2 leads out a signal detection terminal for connecting to a signal detection device. No part of the entire device can move, but because each part is made of flexible material and the overall thickness of the device is very thin, the sensor still has good bending capability.

[0033] During measurement, the comb-like structure of the stepped electrode 2 is connected to the positive terminal of the oscilloscope, while the other end is either suspended or grounded. When an object slides on its surface, due to the principle of triboelectric charging, negative charges accumulate on the surface of the electronegative film. When the external object slides past the electrode, because the two electrodes have different lengths, charge transfer between the two electrodes will be detected on the oscilloscope. When the object slides to the gap between the electrodes, the charge on the electrode will transfer back, generating a reverse voltage signal on the oscilloscope. Based on this rule, when an object slides from one end of the device to the other, the frequency of the signal oscillation is the time interval between the object sliding past each electrode. Therefore, the sliding speed can be easily obtained from the frequency of the signal and the period of the stepped electrode. The sliding displacement is similar; the number of peaks / troughs generated indicates the number of times the device has traversed the electrode / gap. Finally, the sliding direction is determined by the arithmetic progression of the two electrode sections, as shown in the figure. The comb teeth decrease in length from long to short. When the object slides from left to right, although charge is dynamically gained and lost, the total charge increases overall. Therefore, after low-pass filtering the detection signal, the low-frequency signal displayed on the oscilloscope is negative (the excess charge needs to be replenished from the oscilloscope). Conversely, when the sliding direction is from right to left, the charge is lost overall, resulting in a positive low-frequency signal. Therefore, the sliding direction can be determined by the positive or negative sign of the signal.

[0034] Based on the above analysis, the sliding information sensing method using this tactile sensor patch is achieved by decoupling the TENG signal, specifically as follows: Fourier transform is performed on the oscillation signal output from the signal detection terminal of the stepped electrode (2) to extract the frequency f corresponding to the highest frequency peak in the spectrum signal; Multiplying the frequency f by the period of the rectangular electrode arrangement yields the sliding speed of the sliding object. Based on the peaks and / or troughs, count the number of oscillations of the oscillation signal, multiply it by the period of the rectangular electrode arrangement, and obtain the sliding displacement; The oscillation signal is low-pass filtered (<10Hz), and the low-frequency signal obtained is integrated to obtain its sign, which corresponds to the sign of the sliding direction.

[0035] The electronegative film 1 is preferably made of fluorinated ethylene propylene copolymer (FEP), but in practice, polytetrafluoroethylene (PTFE) or silicone rubber can also be used. The first substrate 3 can be made of polyimide (PI).

[0036] In a preferred embodiment, the stepped electrode 2 has a rectangular electrode width of 2 mm, a spacing of 1 mm, and an electrode length ranging from 18 mm to 1 mm, arranged in an arithmetic progression with a difference of 1 mm.

[0037] Example 2 In Embodiment 1, a single comb structure is used, but the right comb tooth is shorter, resulting in less transferred charge and a smaller signal amplitude, which is easily masked by noise, leading to a poor signal-to-noise ratio. To improve the signal-to-noise ratio of the detected signal, Embodiment 2 of this invention provides a sliding tactile sensing patch with a centrally symmetrical comb structure.

[0038] like Figure 3 As shown, the stepped electrode 2 in this embodiment includes a pair of identical comb structures, arranged tooth-to-tooth to form a centrally symmetrical structure. During measurement, one of the two comb structures leads out a signal detection terminal, which is connected to the positive terminal of the detection device, and the other leads out a signal reference terminal, which is connected to the negative terminal of the detection device. Figure 4 The diagram shows the current change of the flexible tactile sensor patch under constant normal force for 20,000 cycles of compression and recovery, illustrating the stability of the sensor's pressure sensing.

[0039] Compared to Example 1, this example boasts a higher signal-to-noise ratio within the same size. The specific analysis is as follows: According to the TENG principle, the generated signal magnitude is proportional to the electrode size. In Example 1, the signal magnitude is proportional to the comb tooth length; to increase the signal amplitude, the overall device width must be increased by lengthening the comb teeth. However, in Example 2, by arranging an identical, centrally symmetrical reference terminal and connecting the reference terminal signal to the oscilloscope's reference ground, the signal magnitude becomes proportional to the length difference between the two comb teeth. This effectively avoids the problem of a small signal amplitude that is easily masked by noise when the slider reaches the end.

[0040] When using the tactile sensor patch of this embodiment, the method of extracting sliding speed, sliding direction and displacement from the detection signal is the same as in Embodiment 1, and will not be repeated here.

[0041] Example 3 Figure 5 This is a structural diagram of the tactile sensing patch for high-precision sliding information sensing in Embodiment 3. The tactile sensing patch includes a TENG sliding sensor assembly and a piezoresistive pressure sensor assembly. As shown in the figure, it specifically includes, from top to bottom, an electronegative thin film 1, a stepped electrode 2, a first substrate 3, a second substrate, an interdigitated electrode 4, a piezoresistive sheet 5, an adhesive material 6, and a flexible buffer layer 7, stacked sequentially. In this embodiment, the first substrate 3 and the second substrate share the same substrate, namely the first substrate 3, on which the stepped electrode 2 and the interdigitated electrode 4 are respectively fabricated on its positive and negative sides to avoid possible relative movement between the two parts.

[0042] Finger electrode 4, etc. Figure 6 As shown. The materials for the interdigitated electrode 4 and the stepped electrode 2 are preferably copper-plated.

[0043] The varistor sheet 5 is fixed by introducing through-grids through laser processing. The varistor sheet can be made of varistor film, so all parts are made of flexible materials and the overall thickness of the device is very thin, which makes the sensor still have good bending ability. Therefore, it is suitable for not only rigid objects, but also flexible objects.

[0044] The adhesive material 6 is used to fix the varistor sheet 5 onto the substrate, preferably fluorinated ethylene propylene copolymer (FEP). The flexible buffer layer 7 is used to dampen the pressure on the component, preferably Ecoflex silicone rubber.

[0045] In a preferred embodiment, the overall size of the device is 55mm*20mm, and the overall thickness is approximately 3mm. The interdigitated electrodes are spaced 1mm apart. The varistor sheet measures 45mm*12mm, with two 1mm*40mm holes in the center for fixing the varistor sheet.

[0046] In the pressure sensing section, interdigitated electrodes and a varistor are used. When pressure is applied to the device surface, the conductive paths in the varistor film increase, and the resistance decreases. The pressure sensing section and the sliding sensing section are led out through separate circuits, isolating interference between the signals on both sides at the device level.

[0047] Example 4 This embodiment provides a method for preparing the sensor of the present invention, comprising the following steps: Step 1: Stepped electrode 2 and interdigitated electrode 4 are fabricated on both sides of the common substrate of the TENG sliding sensor assembly and the piezoresistive pressure sensor assembly using a template copper plating process.

[0048] Step 2: Fabrication of the sliding sensing part: Attach the electronegative thin film 1 to the side of the prepared stepped electrode 2.

[0049] In this step, the FEP electronegative film is cut to the same size as the sensor using a laser cutter and then carefully attached to the prepared stepped electrode side.

[0050] Step 3: Preparation of pressure sensing part: Laser cut the piezoresistive sheet 5 to the size of the design parameters, use adhesive material 6 to stick it to the side of the prepared interdigitated electrode 4, then apply the material of the flexible buffer layer 7 to the pressure sensing side of the piezoresistive sheet that has been pasted, cure it at the specified temperature, remove the excess part of the flexible buffer layer material, and obtain the tactile sensing patch.

[0051] In this step, the Velostat varistor is laser-cut to the size specified in the design parameters. Then, it is attached to the prepared interdigitated electrode side using FEP tape. Next, the A and B components of Ecoflex 00-30 silicone rubber are mixed in a 1:1 ratio and applied to the pressure sensing side of the attached varistor. After curing at 50°C for 3 hours, the excess silicone rubber is carefully removed with a blade to obtain the final device.

[0052] In summary, the embodiments of this invention propose a tactile sensor patch with high-precision sliding information sensing capability. Employing a stepped electrode structure, it encodes and retains information on sliding speed, direction, and displacement generated during the sliding process, and decouples and reconstructs this sliding information in subsequent processing. Compared to traditional tactile sensors that can only detect whether sliding has occurred, this sensor detects sliding information with higher dimensions, which helps intelligent grippers accurately determine the gripping state. Furthermore, because this sensor is small and lightweight, it can be attached to any surface, thus enabling its application in most scenarios.

[0053] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-precision sliding information sensing patch for tactile sensation, characterized in that, Including the TENG sliding sensor assembly, a triboelectric nanogenerator; The TENG sliding sensor assembly includes an electronegative thin film (1), a stepped electrode (2), and a first substrate (3) stacked from top to bottom. The stepped electrode (2) includes: a comb structure consisting of rectangular electrodes arranged at intervals and connecting bridges connecting each rectangular electrode at one end; the rectangular electrodes have the same width, fixed intervals, and are arranged in an arithmetic sequence in length. The stepped electrode (2) leads out a signal detection terminal for connecting to a signal detection device; The signal output from the step electrode (2) signal detection end is a periodic oscillation signal. The oscillation frequency of the oscillation signal expresses the sliding speed of the sliding object, the number of oscillations of the oscillation signal expresses the sliding displacement of the sliding object, and the positive and negative signs of the low-frequency signal of the oscillation signal express the sliding direction of the sliding object.

2. The tactile sensor patch as described in claim 1, characterized in that, The stepped electrode (2) consists of a pair of identical comb structures arranged in a tooth-to-tooth configuration to form a centrally symmetrical structure; one of the two comb structures leads out a signal detection terminal and connects to the positive terminal of the detection device, and the other leads out a signal reference terminal and connects to the negative terminal of the detection device.

3. The tactile sensor patch as described in claim 1 or 2, characterized in that, In the stepped electrode (2), the rectangular electrode has a width of 2 mm and a spacing of 1 mm. The electrode length ranges from 18 mm to 1 mm and is arranged in an arithmetic progression with a difference of 1 mm.

4. The tactile sensor patch as described in claim 1, characterized in that, The electronegative material used in the electronegative film (1) is fluorinated ethylene propylene copolymer (FEP), polytetrafluoroethylene (PTFE), or silicone rubber.

5. The tactile sensor patch as described in any one of claims 1-4, characterized in that, The tactile sensor patch further includes a piezoresistive pressure sensor assembly, which consists of a second substrate, interdigitated electrodes (4), a pressure-sensitive resistor sheet (5), an adhesive material (6), and a flexible buffer layer (7) connected in sequence; the second substrate is interconnected with the first substrate.

6. The tactile sensor patch as described in claim 5, characterized in that, The second substrate is the same as the first substrate, and a stepped electrode (2) and an interdigitated electrode (4) are respectively prepared on the positive and negative sides.

7. The tactile sensor patch as described in claim 6, characterized in that, The interdigitated electrodes (4) are spaced 1 mm apart; the adhesive material (6) is fluorinated ethylene propylene copolymer (FEP); the flexible buffer layer (7) is made of Ecoflex silicone rubber.

8. The tactile sensor patch as described in claim 5, characterized in that, The substrate material is polyimide (PI).

9. A sliding information sensing method, characterized in that, The method, employing a high-precision sliding information sensing patch as described in any one of claims 1-8, comprises: Fourier transform is performed on the oscillation signal output from the signal detection terminal of the stepped electrode (2) to extract the frequency f corresponding to the highest frequency peak in the spectrum signal; Multiplying the frequency f by the period of the rectangular electrode arrangement yields the sliding speed of the sliding object. Based on the peaks and / or troughs, count the number of oscillations of the oscillation signal, multiply it by the period of the rectangular electrode arrangement, and obtain the sliding displacement. The oscillation signal is low-pass filtered, and the low-frequency signal obtained is integrated to obtain its sign, which corresponds to the sign of the sliding direction.

10. A method for preparing a high-precision sliding information sensing patch according to any one of claims 5-8, characterized in that, include: Step 1: Stepped electrodes (2) and interdigitated electrodes (4) are prepared on both sides of the common substrate of the TENG sliding sensor assembly and the piezoresistive pressure sensor assembly using a template copper plating process. Step 2: Attach the electronegative thin film (1) to the side of the prepared stepped electrode (2); Step 3: Laser cut the varistor sheet (5) to the size of the design parameters, use adhesive material (6) to stick it to the prepared interdigitated electrode (4) side, then apply the material of the flexible buffer layer (7) to the pressure sensing side of the varistor sheet that has been pasted, cure it at the specified temperature, remove the excess part of the flexible buffer layer material, and obtain the tactile sensing patch.

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