Double-helix touch sensor and preparation method thereof

Abstract

The invention provides a double-helix tactile sensor and a preparation method thereof, the double-helix tactile sensor comprises a substrate film, an electrode layer and a covering layer, copper foil is arranged on the substrate film, the electrode layer is arranged on the substrate film, the electrode layer comprises shielding laid copper, a double-helix electrode and a plurality of contacts arranged on the double-helix electrode, the covering layer is arranged on the electrode layer, and the shielding laid copper is arranged on the covering layer. The plurality of elliptical holes in the covering layer correspond to the plurality of contacts on the electrode layer, and the substrate film, the electrode layer and the covering layer jointly form the double-helix tactile sensor. According to the invention, a double-helix electrode structure and a plurality of contacts arranged on the double-helix electrodes are arranged, the difference of output voltage peak values at two ends of the chip resistors on the two helix electrodes is compared, binary coding is introduced, so that the algorithm is simplified, and meanwhile, a human body coupling sensing mechanism using a power frequency electric field as an energy source is adopted, so that the sensing precision is improved. The method has the advantages of low detection limit, good durability, robustness, high expandability and fast coding capability.

Description

Technical Field

[0001] The present invention relates to the technical field of tactile sensors, and in particular to a double-helix tactile sensor and a preparation method thereof. Background Art

[0002] As a human-computer interaction interface, tactile sensors have irreplaceable advantages such as accurate interaction process and fast response speed. Limited by the sensor power supply method, tactile sensors are currently divided into two categories: tactile sensors powered by wires and battery-based tactile sensors. However, tactile sensors powered by wires have problems such as redundant cables and electromagnetic interference; traditional battery-based tactile sensors have inherent defects such as short service life, limited capacity, regular charging and replacement, and high environmental risks, and cannot meet the future sustainable and environmentally friendly energy needs; more importantly, the existing human-computer interaction interface for touch perception usually requires a large number of sensor elements and electrodes, which increases power consumption and has defects such as complex structure and poor scalability.

[0003] In summary, there is an urgent need to develop a battery-free and highly scalable tactile sensor as a human-computer interaction interface. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a double-helix tactile sensor and a preparation method thereof, which does not require battery or external power supply, and introduces binary coding through a double-helix electrode structure and a plurality of contact points arranged on the double-helix electrode, thereby simplifying the algorithm. At the same time, the tactile sensor achieves the advantages of low detection limit, good durability, robustness, high scalability and fast coding capability through a human body coupling sensing mechanism that adopts an industrial frequency electric field as an energy source.

[0005] The technical solution adopted by the present invention is a double-helix tactile sensor, which includes a base film, an electrode layer and a covering layer, wherein the base film is provided with a copper foil; the electrode layer is provided on the base film, and the electrode layer includes a shielding copper plating, a double-helix electrode and a plurality of contacts provided on the double-helix electrode; a shielding copper plating area and an electrode laying area are provided on the electrode layer, and the shielding copper plating is provided at the shielding copper plating area; the double-helix electrode is provided in the electrode laying area, and the intersection of the two diagonals of the base film is used as the electrode rotation center of the double-helix electrode, and the double-helix electrode includes a first electrode and a second electrode, and the first electrode and the second electrode both rotate around the electrode The invention relates to an Archimedean spiral electrode in the center, and the first electrode is located on the inner side of the second electrode, the first electrode and the second electrode are evenly distributed in a plurality of sliding directions around the rotation center of the electrodes, and a plurality of contacts are arranged in each sliding direction, and the first electrode and the second electrode of each circle have and only have one contact in the same sliding direction, and the terminal ends of the first electrode and the second electrode are both provided with chip resistors, and both ends of the chip resistors are provided with grounding terminals; the covering layer is the same size as the base film, a plurality of elliptical holes are arranged on the covering layer, the covering layer is arranged on the electrode layer, and the plurality of elliptical holes on the covering layer correspond to the plurality of contacts on the electrode layer.

[0006] Furthermore, since the peak value of the voltage signal across the patch resistor when the contact is touched is greater than the peak value of the voltage signal across the patch resistor when the contact is not touched, when the peak value of the voltage signal across the patch resistor of the first electrode is greater than the peak value of the voltage signal across the patch resistor of the second electrode, the first electrode generates a coding signal, otherwise the second electrode generates a coding signal; assuming that the coding signal generated when the contact on the first electrode is touched is 0, and the coding signal generated when the contact on the second electrode is touched is 1, when different directions are touched, different binary coding sequences can be generated in the corresponding directions and coding signals can be formed, thereby identifying the sliding direction.

[0007] Preferably, both the first electrode and the second electrode are Archimedean spiral electrodes, and the polar coordinate expression of the axis of the first electrode is:

[0008] ρ1=e+b·α2π

[0009] Wherein, e represents the starting radius of the first electrode axis; b represents the axis density of the first electrode, and α represents the rotation angle of the electrode;

[0010] The polar coordinate expression of the second electrode axis is:

[0011] ρ2=c+d·α2π

[0012] Wherein, c represents the starting radius of the axis of the second electrode; d represents the axis density of the second electrode.

[0013] Preferably, the base film and the covering layer are square, the square width is 116 mm, the width of the first electrode and the second electrode are both 1.5 mm, and the spacing between the first electrode and the shielding copper is 1 mm, the spacing between adjacent first and second electrodes is 0.5 mm, and the spacing between the inner spiral and the outer spiral in the double spiral electrode is 10 mm.

[0014] Furthermore, when the contact point is not touched, the voltage signals across the chip resistors of the first electrode and the second electrode are:

[0015]

[0016] In the formula, R DS Represents the chip resistance on a single electrode. A, B, C, and D are represented by the following formulas, specifically:

[0017]

[0018] Where f represents the frequency of the coupled AC power supply, C sup1 Represents the coupling capacitance between the left end of the chip resistor of the first electrode and the power line, C sup2 Represents the coupling capacitance between the right end of the chip resistor of the second electrode and the power line, R iso Represents the resistance of the data acquisition device, V a Indicates the grid voltage, C iso Represents the ground capacitance of the data acquisition equipment;

[0019] When the contact is touched, the signal generated by the coupled electric field of the human body is transmitted to the electrode corresponding to the touched contact, and the patch resistor on the touched electrode provides a symmetrical signal with positive and negative amplitudes. At this time, the voltage output signal of the patch resistor on the touched electrode is:

[0020]

[0021] In the formula, E, F, G, and H are respectively expressed by the following formulas:

[0022]

[0023] In the formula, C b Represents the coupling capacitance between the human body and the earth, C p Represents the coupling capacitance between the power line and the human body in the surrounding environment, R h Represents the equivalent resistance of the human body, C h Represents the equivalent capacitance of the human body, R q Indicates the contact resistance between the human body and the contact point.

[0024] Furthermore, the number of sliding directions that can be detected by different electrodes on the electrode layer is expressed as:

[0025] N=m α / 2π

[0026] Wherein, m represents the number of electrodes provided on the electrode layer, and α represents the rotation angle of the electrode.

[0027] Preferably, the base film and the cover layer are both rectangular PI films of set sizes.

[0028] Preferably, the rotation angle of the Archimedean spiral electrode is 6π.

[0029] Another aspect of the present invention provides a method for preparing a double-helix tactile sensor, comprising the following steps:

[0030] S1, cutting the copper-plated PI film into a set shape and size;

[0031] S2, preparing shielding copper and double spiral electrodes on the copper-plated PI film to obtain an electrode layer;

[0032] S3, cutting a piece of PI film of the same size as the copper-plated PI film to obtain a covering layer;

[0033] S4, according to the contact points set in different sliding directions of the double spiral electrode and the position of the patch resistor, using laser cutting to process the touch holes and the patch resistor holes on the cover layer PI film;

[0034] S5, placing the cover layer PI film on the electrode layer, the touch holes corresponding to the contacts arranged on the double spiral electrodes, and pressing the copper-plated PI film and the cover layer PI film together by high temperature and high pressure, thereby forming a plurality of contacts;

[0035] S6, providing a gold plating layer at the corresponding chip resistor hole on the copper-plated PI film, and welding the chip resistor to the terminal ends of the first electrode and the second electrode in the double spiral electrode;

[0036] S7, the copper-plated PI film, the double-helix electrode and the covering layer PI film together constitute a tactile sensor with a double-helix structure, thereby completing the production of the double-helix tactile sensor.

[0037] Furthermore, in step S2, shielding copper and double-helix electrodes are prepared on the copper-plated PI film to obtain an electrode layer, and the specific steps include:

[0038] S21, fixing the copper-plated PI film on a pad, machining positioning holes on the copper-plated PI film, and cleaning the surface of the copper-plated PI film to remove the oxide layer on the surface of the copper-plated layer;

[0039] S22, adhering a photoresist film to the surface of the copper layer in the copper-plated PI film, and aligning a film with a double spiral electrode pattern with the positioning hole on which the photoresist film has been adhered;

[0040] S23, transferring the pattern on the film to the photoresist film by optical imaging, and irradiating the film with an exposure light source to make the shielding copper and double spiral electrode patterns on the film sensitive to light;

[0041] S24, using a developer to remove the photoresist film in the unexposed area, so that the shielding copper in the unexposed area on the surface of the copper-plated PI film is revealed;

[0042] S25, retaining the photoresist film pattern at the exposed area, corroding the copper layer exposed after development with an etching solution, and retaining the area covered by the photoresist film;

[0043] S26, using a stripping solution to remove the etched photoresist film to reveal the desired double spiral electrode and shielding copper pattern, at which time a double spiral electrode is formed on the surface of the copper layer in the copper-plated PI film;

[0044] S27, completing the preparation of the double spiral electrode.

[0045] The characteristics and beneficial effects of the present invention are:

[0046] 1. The double-helix tactile sensor and preparation method thereof provided by the present invention compares the difference in the output voltage peaks of the chip resistor of the first electrode and the chip resistor of the second electrode, adopts the encoding rules of the binary bits "0" and "1", sets the encoding signal generated when the touch point on the first electrode is touched to 0, and sets the encoding signal generated when the touch point on the second electrode is touched to 1. When different directions are touched, different binary encoding sequences can be generated in the corresponding directions to form encoding signals. Only two interfaces are used to identify the detection of sliding directions in multiple directions, and it has the advantages of a small number of interfaces, a simple reading algorithm and strong anti-interference ability.

[0047] 2. The double-helix tactile sensor and preparation method provided by the present invention increase the number of double-helix electrodes and the electrode rotation angle on the electrode layer, and set multiple contact arrangements on the double-helix electrodes, thereby increasing the number of detectable sliding directions on the electrode, and has excellent scalability and applicability.

[0048] 3. The double-helix tactile sensor and its preparation method provided by the present invention convert the industrial frequency electric field in the environment into a usable sensing energy source by means of human body coupling, introduce binary coding through the double-helix electrodes and the multiple contacts arranged thereon, and its energy generation does not rely on mechanical movement, and has the advantages of no need for external power supply and battery and simple structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic diagram of the structure of the tactile sensor of the present invention;

[0050] Figure 2 is a plan view schematic diagram of a tactile sensor having eight sliding directions according to the present invention;

[0051] Figure 3 It is a schematic diagram of the working principle of the tactile sensor of the present invention;

[0052] Figure 4 It is a schematic diagram of the body-coupled sensing mechanism of the present invention using the industrial frequency electric field as the energy source;

[0053] Figure 5 It is a schematic diagram of an equivalent circuit of a body-coupled sensing mechanism of the present invention using an industrial frequency electric field as an energy source;

[0054] Figure 6 is a schematic diagram of an output voltage signal of the tactile sensor when a finger passes over a single electrode of the present invention;

[0055] Figure 7 It is a schematic diagram of an equivalent circuit of the coupling effect between the power frequency electric field, the tactile sensor and the acquisition device when there is no contact in the present invention;

[0056] Figure 8 It is a schematic diagram of an equivalent circuit of the coupling effect between the power frequency electric field, the human body, the tactile sensor and the acquisition device during contact in the present invention;

[0057] Fig. 9 It is a schematic diagram of the generation of the coding signal "001" when a finger passes by the present invention;

[0058] Fig.10 is a schematic diagram of output voltage responses when different users slide on the first electrode and the second electrode of the tactile sensor for multiple times;

[0059] Fig.11 is a schematic diagram of the output voltage response of the tactile sensor when different contact forces are applied in the present invention;

[0060] Fig.12 It is a schematic diagram of the output voltage response of the tactile sensor with or without contact and the amplitude ratio with or without contact in different electric field environments of the present invention;

[0061] Fig.13 is a schematic diagram of an electrode structure of a tactile sensor having 16 sliding directions according to the present invention;

[0062] Fig.14 It is a schematic diagram of the electrode structure of the tactile sensor with 8 sliding directions and the corresponding coding signals of different sliding directions of the present invention;

[0063] Fig.15 It is a schematic diagram of coding signals of different sliding directions of a tactile sensor with 16 sliding directions according to the present invention;

[0064] Fig.16 This is a working principle diagram of the present invention controlling a single leg of a robot through a tactile sensor;

[0065] Fig.17 It is an operation demonstration of controlling the robot leg movement by means of a tactile sensor and a schematic diagram of the corresponding output signal of the present invention;

[0066] Fig.18 It is a schematic flow diagram of the preparation method of the present invention;

[0067] Fig.19 is a schematic diagram of the manufacturing process of the tactile sensor of the present invention;

[0068] Fig. 20 The present invention is a flow chart of preparing shielded copper plating and double spiral electrodes on a copper-plated PI film.

[0069] Main reference numerals:

[0070] Base film 1; electrode layer 2; shielding copper 21; contact 22; first electrode 23; second electrode 24; chip resistor 25; ground terminal 26; cover layer 3; elliptical hole 31. DETAILED DESCRIPTION

[0071] In order to fully describe the technical content, structural features, objectives and effects of the present invention, the following will be described in detail with reference to the accompanying drawings.

[0072] A double-helix tactile sensor of the present invention, such as Figure 1 and Figure 2As shown, it includes a base film 1, an electrode layer 2 and a covering layer 3, the base film 1 is a rectangular film cut to a set size, and a copper foil is provided on the base film 1; the electrode layer 2 is provided on the base film 1, and the electrode layer 2 includes a shielding copper plating 21, a double spiral electrode and a plurality of contacts 22 provided on the double spiral electrode, a shielding copper plating area and an electrode laying area are provided on the electrode layer 2, and the shielding copper plating 21 is provided in the shielding copper plating area, a double spiral electrode is provided in the electrode laying area, and the intersection of the two diagonals of the base film 1 is used as the electrode rotation center of the double spiral electrode, and the double spiral electrode includes a first electrode 23 and a second electrode 24, both of which are Archimedean spiral electrodes with a rotation angle of 6π around the electrode rotation center, and the first electrode 23 is located on the inner side of the second electrode 24. , the first electrode 23 and the second electrode 24 are evenly distributed in 8 sliding directions around the electrode rotation center, and 3 contacts 22 are arranged in each sliding direction, and each circle of the first electrode 23 and the second electrode 24 has and only has 1 contact 22 in the same sliding direction, and the combination order of each group of contacts on the first electrode and the second electrode in different directions cannot be the same, and the terminal ends of the first electrode 23 and the second electrode 24 are provided with chip resistors 25, and both ends of the chip resistors 25 are provided with grounding terminals 26; the covering layer 3 is a rectangular film cut to a set size, and the covering layer 3 has the same size as the base film 1, and a plurality of elliptical holes 31 are arranged on the covering layer 3, and the covering layer 3 is arranged on the electrode layer 2, and the plurality of elliptical holes 31 on the covering layer 3 correspond to the plurality of contacts 22 on the electrode layer 2.

[0073] In a preferred embodiment, both the base film 1 and the cover layer 3 are rectangular PI films of set sizes.

[0074] like Figure 2 As shown, the width w1 of the square tactile sensor is 116 mm, the electrode width w2 is 1.5 mm, the spacing g1 between the first electrode 23 and the shielding copper 21 is 1 mm, the spacing g2 between the adjacent first electrode 23 and the second electrode 24 is 0.5 mm, the spacing g3 between the inner spiral and the outer spiral of the double spiral electrode structure is 10 mm, and the polar coordinate expression of the axis of the first electrode 23 is:

[0075] ρ1=12.25+13.5·α2π (0<α<6π).

[0076] The polar coordinate expression of the second electrode axis is:

[0077] ρ2=14.25+13.5·α2π(0<α<6π)

[0078] Where α represents the rotation angle of the electrode.

[0079] The contact profile expression is:

[0080]

[0081] Wherein, x represents the independent variable, y represents the dependent variable, q1 represents the length of the minor semi-axis of the elliptical contact, and q2 represents the length of the minor semi-axis of the elliptical contact.

[0082] like Figure 3 As shown, electronic devices commonly used in daily life (computers, air conditioners, electric lights, etc.) and AC power transmission lines will generate power frequency electric fields. This low-frequency electric field will produce quasi-static induction effects in the air and human body. Since the human body has a very high relative dielectric constant and conductivity compared to air, in the same environment, the induced potential difference generated by this effect in the human body is much greater than the potential difference generated in the air. When the electric field directly acts on the tactile sensor, the induction effect in the air causes a small voltage signal to be generated at both ends of the tactile sensor patch resistor. When a human hand touches the contact of the tactile sensor, the human body transfers the induced potential difference generated by the electric field source to the electrode of the tactile sensor through quasi-static induction, and a large voltage signal is induced at both ends of the resistor connected to the electrode. Therefore, when a finger slides over the tactile sensor, multiple groups of output signals with different peak values ​​will be generated, thereby forming a coded signal. The coded signal is then processed by a computer to generate a control command, thereby realizing the control of the robot.

[0083] like Figure 4 As shown in the figure, in the power frequency electric field environment, the electric field energy collected under human coupling is significantly higher than that under air coupling. When the human body does not touch the tactile sensor, the electric field energy in the environment is transmitted through the path formed by the air, the tactile sensor and the ground (transmission path 2); when the human body touches the tactile sensor, the electric field energy in the environment mainly forms a new transmission path (transmission path 1) through the human body, the tactile sensor and the ground; when the human body is separated from the tactile sensor, the transmission path will return to its original state. Through this change in the transmission path, the tactile sensor can work.

[0084] like Figure 5 As shown in the figure, the process of the finger moving away from, approaching, and touching the tactile sensor can be equivalent to three different circuit loops (I), (II), and (III). The human body can be equivalent to a series of capacitors and resistors, the tactile sensor can be approximated as a high-resistance resistor, and the data acquisition device used for differential measurement can be equivalent to the following: Figure 5 The capacitor C p Indicates the coupling capacitance between 220V AC and the human body, C sup1 is the coupling capacitance between the left end of the patch resistor of the first electrode and the power line, C sup2 is the coupling capacitance between the right end of the patch resistor of the second electrode and the power line, capacitance C b Represents the coupling capacitance between the human body and the ground, Ciso These coupling capacitors allow weak displacement current to pass through. When the human body is away from the tactile sensor (stage I), the displacement current passes through the coupling capacitor C sup1 , C sup2 Flows into the tactile sensor, then passes through the data acquisition device and the coupling capacitor C iso When the human body approaches the touch sensor (phase II), the displacement current flows through the coupling capacitor C p It flows into the human body, then flows into the data acquisition device through the tactile sensor through the coupling capacitance generated between the air and the finger, and then flows into the data acquisition device through the coupling capacitor C iso Flows into the ground; when the human body touches the touch sensor (stage III), the displacement current flows through the coupling capacitor C p It flows into the human body, passes through the chip resistor 25 in the tactile sensor, and then flows into the data acquisition device, and then passes through the coupling capacitor C iso It is worth noting that when the human body does not touch the tactile sensor, one end of the tactile sensor's chip resistor is connected to the spiral electrode, and the other end is directly connected to the data acquisition device, resulting in the coupling capacitance C between the two ends of the tactile sensor and the power line. sup1 , C sup2 The difference in size is the main reason why a sinusoidal potential difference is generated across the resistor of the tactile sensor patch.

[0085] like Figure 6 As shown, the process of the finger sliding over the first electrode 23 can be divided into five stages. i) The first stage: When the finger is away from the first electrode 23, the induced potential difference in the human body will be offset by the potential generated in the shielding copper 21, and only the voltage signal with an average peak value of 0.065V is on the first electrode 23; ii) The second stage: When the finger approaches the first electrode 23, a capacitive effect is formed between the human body and the first electrode 23, and the charge is conducted to the first electrode 23 through electric field coupling, and the peak value of the voltage signal increases from 0.065V to 0.089V; iii) The third stage: When the finger contacts the first electrode 23, the charge is directly conducted from the human body to the first electrode 23, and the peak value of the voltage signal increases significantly and stabilizes at 0.23V; iv) The fourth stage: When the finger leaves the first electrode 23, the peak value of the generated voltage signal first decreases significantly to 0.072V; v) The fifth stage: The generated voltage signal gradually decreases and stabilizes at 0.054V.

[0086] like Figure 7 As shown in the figure, it is the equivalent circuit of the coupling between the power frequency electric field, the tactile sensor and the acquisition device when there is no contact, where the capacitor C p Represents the coupling capacitance between the power line and the human body in the surrounding environment, C b Represents the coupling capacitance between the human body and the ground, C isois the grounding capacitance of the data acquisition equipment, C sup1 is the coupling capacitance between the left end of the patch resistor of the first electrode and the power line, C sup2 is the coupling capacitance between the right end of the patch resistor of the second electrode and the power line, R DS is the chip resistance on a single electrode in the tactile sensor, R iso is the resistance of the data acquisition device, f is the frequency of the coupled AC power supply, V a is the grid voltage. I1, I2, I3, I4, I5, and I6 represent the current flowing through C sup1 , C sup2 , R DS , Left R iso , right side R iso , C iso of current.

[0087] The loop formed by I1, I3, I5, and I6 flowing through the circuit structure can be obtained based on Ohm's law:

[0088]

[0089] The loop formed by I1, I4, and I6 flowing through the circuit structure can be obtained based on Ohm's law:

[0090]

[0091] The loop formed by I2, I5, and I6 flowing through the circuit structure can be obtained based on Ohm's law:

[0092]

[0093] At points a, b, and c, Kirchhoff's current law gives:

[0094] I1-I3-I4=0(4)

[0095] I2+I3-I5=0(5)

[0096] I4+I5-I6=0(6).

[0097] The matrix equation is obtained from formulas (1) to (6):

[0098]

[0099] The voltage signal V across the chip resistor 25 of the first electrode 23 and the second electrode 24 is obtained. DS for:

[0100]

[0101] In the formula, R DSThe chip resistance on a single electrode in the tactile sensor, A, B, C, D are respectively expressed by the following formulas, specifically:

[0102]

[0103] It can be seen that when the human body does not touch the tactile sensor, the first end of the resistor of the tactile sensor is connected to the spiral electrode, and the second end is directly connected to the acquisition device, resulting in the coupling capacitance C between the two ends of the tactile sensor and the power line. sup1 , C sup2 The difference in size is the main reason why a small sinusoidal potential difference is generated across the resistance of the tactile sensor.

[0104] like Figure 8 As shown in the figure, it is an equivalent circuit of the coupling effect between the power frequency electric field, human body, tactile sensor and acquisition equipment during contact. When the tactile sensor is not touched, the signal generated by the coupled electric field of the human body is not transmitted to the sensing element. When the contact point is touched, the signal generated by the coupled electric field of the human body is transmitted to the electrode corresponding to the touched contact point, and the patch resistor on the touched electrode provides a symmetrical signal with positive and negative amplitudes. p Represents the coupling capacitance between the power line and the human body in the surrounding environment, C b Represents the coupling capacitance between the human body and the ground, C iso is the grounding capacitance of the data acquisition equipment, C h is the equivalent capacitance of the human body, R h is the equivalent resistance of the human body, R q is the contact resistance between the human body and the touch sensor contact, R DS is the chip resistance on a single electrode of the component, R iso is the resistance of the data acquisition device, f is the frequency of the coupled AC power supply, V a is the grid voltage. 1' ,I 2' ,I 3' ,I 4' ,I 5' ,I 6' Respectively represent the flow through C p , C b , R q , R DS , Left R iso , Ciso current.

[0105] By I 1' ,I 2' The flow through the loop formed by the circuit structure gives the equation:

[0106]

[0107] By I 1' ,I3' ,I 4' ,I 6' The flow through the loop formed by the circuit structure gives the equation:

[0108]

[0109] By I 1' ,I 3' ,I 5' ,I 6' The flow through the loop formed by the circuit structure gives the equation:

[0110]

[0111] At points a, b, and c, Kirchhoff's current law gives:

[0112] I1'-I2'-I3'=0(12)

[0113] I3'-I4'-I5'=0(13)

[0114] I4'+I5'-I6'=0(14).

[0115] The matrix equation is obtained from formulas (9) to (14):

[0116]

[0117] The voltage output signal V of the chip resistor on the touched electrode is obtained DS for:

[0118]

[0119] In the formula, E, F, G, and H are respectively expressed by the following formulas:

[0120]

[0121] It can be seen that the coupling capacitance C between the power line and the human body in the surrounding environment p , the coupling capacitance between the human body and the ground C b And the series resistance R used by a single electrode on the component DS Will affect the voltage output signal V DS Compared with formula (16), formula (8) shows that the coupling capacitance C between the power line and the human body in the same environment is p Much larger than the coupling capacitance C between the two ends of the touch sensor and the power line sup1 , C sup2 , the output voltage V of the tactile sensor obtained by formula (16) DS is greater than the voltage obtained by formula (8).

[0122] According to formulas (8) and (16), when there is only a tactile sensor in the electric field, the induction effect in the air generates a voltage signal with a small peak value at both ends of the resistor of the tactile sensor. When a human hand touches the electrode of the tactile sensor, the human body transfers the induced potential difference generated by the electric field source to the electrode of the tactile sensor through quasi-static induction, and a voltage signal with a large peak value is induced at both ends of the resistor connected to the electrode. Therefore, when a finger slides over different electrodes of the tactile sensor, output signals with different peak values ​​will be generated on the corresponding electrodes. When the contact point located at the first electrode 23 is touched, a voltage signal with a large peak value will be induced at both ends of the patch resistor 25 connected to the first electrode 23, that is, the coding signal generated by the first electrode 23; when the contact point located at the second electrode 24 is touched, a voltage signal with a large peak value will be induced at both ends of the patch resistor 25 connected to the second electrode 24, that is, the coding signal generated by the second electrode 24. The coding signal generated by the first electrode 23 is set to "0", and the coding signal generated by the second electrode 24 is set to "1". By opening the electrodes in different directions differently, when the finger slides in different directions, the tactile sensor generates different coding sequences, thereby forming a coding signal, and then identifying the direction of the finger sliding.

[0123] It should be pointed out here that although multiple factors may affect the peak value of the output voltage, the encoding mechanism proposed in the present application depends only on the relative change of the output voltage peak values ​​in the two electrodes, that is, when the voltage signal changes, the electrode generating the encoding signal is determined by comparing the output voltage peak values ​​in the first electrode and the second electrode, rather than the absolute amplitude, thereby realizing the recognition of the encoding information of the tactile sensor.

[0124] like Fig. 9 As shown, when the user touches the contact point located on the first electrode 23, the contact point on the first electrode 23 generates a coded signal 0, and when the user touches the contact point located on the second electrode 24, the contact point on the second electrode 24 generates a coded signal 1. When the user slides in different directions on the tactile sensor, the tactile sensor can generate different binary coding sequences in the corresponding directions, thereby forming a coded signal, and the foot-type robot can then identify the sliding direction of the user.

[0125] like Fig. 9The figure shows a schematic diagram of the generation of the coding signal "001" when a finger passes through. The present invention takes the process of generating the coding signal "001" as an example. When the finger slides from the middle area over the contact points in different directions, the finger will contact the contact points and generate a voltage signal. When the finger slides over the two electrodes for the first time, since the covering layer of the first electrode 23 has a window, and the covering layer of the second electrode 24 has no window, the finger contacts the first electrode 23, and a voltage signal with a larger peak value is generated on the first electrode 23, and the finger does not contact the second electrode 24, and a voltage signal with a smaller peak value is generated on the second electrode 23, thereby forming a coding signal "0"; similarly, when the finger slides over the two electrodes for the second time, the finger contacts the first electrode 23, and a voltage signal with a larger peak value is generated on the first electrode 23, and the finger does not contact the second electrode 24, and a voltage signal with a smaller peak value is generated on the second electrode 24, thereby forming a second coding signal "0"; when the finger slides over the two electrodes for the third time, the finger contacts the second electrode 24, and a voltage signal with a larger peak value is generated on the second electrode 24, and the finger does not contact the first electrode 23, and a voltage signal with a smaller peak value is generated on the first electrode 23, thereby forming a coding signal "1"; finally, when the finger slides over the two spiral electrodes of the tactile sensor, a binary code "001" is formed.

[0126] like Fig.10 As shown in FIG. 1 , the output voltage response of different users when sliding on the first electrode and the second electrode of the tactile sensor multiple times. Under the same environment, five volunteers slid on the tactile sensor 24 times in the same way. The voltage signals V1 and V2 generated on the first electrode and the second electrode are as follows: Figure 7 The experimental results show that although there are certain differences in the signals generated by different people when sliding, this does not affect the normal use of the tactile sensor, indicating that it has good robustness.

[0127] like Fig.11 The figure shows the output voltage response of the tactile sensor when different contact forces are applied. When the area of ​​the contact point is 10mm×10mm, the output voltage of the tactile sensor does not change significantly when the contact point is pressed with different forces. Even when the contact force is as low as 0.02N, the tactile sensor can still work normally, showing an ultra-low detection limit.

[0128] like Fig.12As shown in the figure, the output voltage response of the tactile sensor with and without contact and the amplitude ratio with and without contact in different electric field environments. In order to simulate the electric field environment in daily life, the test uses a mobile phone charger as the electric field source to compare the output voltage response at different distances. The output voltage amplitude ratio with and without contact is used to evaluate the signal's recognizability. The larger the amplitude ratio, the lower the difficulty of identifying the voltage output signal. As can be seen from the figure, as the distance from the electric field source increases, the amplitude ratio of the voltage output signal during contact and the output voltage signal without contact gradually decreases. When the distance increases from 0.3m to 2m, the output voltage peak of the tactile sensor drops from 0.185V to 0.0109V, and the amplitude ratio drops from 9.59 to 1.23. This is because when the human body and the tactile sensor are far away from the electric field source, the coupling capacitance C between them and the power line p The output voltage will decrease gradually. The results show that the tactile sensor can still work normally even in a weak electric field environment.

[0129] like Fig.13 As shown in the figure, the expression for the number of sliding directions that can be detected by different electrodes on the electrode layer is:

[0130] N=m α / 2π

[0131] Wherein, m represents the number of electrodes provided on the electrode layer, and α represents the rotation angle of the electrode.

[0132] When two electrodes with a rotation angle of 6π are used, the number of detectable sliding directions is 8, i.e., 2 3 When two electrodes with a rotation angle of 8π are used, the number of detectable sliding directions is 16, i.e., 2 4 Increasing the number of electrodes and the rotation angle can significantly increase the number of directions that the tactile sensor can detect. Therefore, the resolution of the finger sliding direction detection of the tactile sensor can be flexibly adjusted as needed, with excellent scalability.

[0133] like Fig.14 As shown, the electrode structure of the tactile sensor with 8 sliding directions and the corresponding coding signals of different sliding directions, the tactile sensor with 8 sliding directions can realize 3-bit binary coding:

[0134] "000", "001", "010", "011", "100", "101", "110" and "111". The tactile sensor successfully implemented 3-bit binary encoding through multiple sets of output signals with different peak values.

[0135] like Fig.15 As shown, the coded signals of different sliding directions of the tactile sensor with 16 sliding directions are realized by arranging four different contact points in each sliding direction, thereby realizing 4-bit binary coding of the 16 sliding directions.

[0136] like Fig.16 As shown in the figure, the working principle diagram of controlling a single leg of a robot through a tactile sensor can be used as a control interface for the movement of the robot's legs. First, the dSPACE controller collects the voltage output signal generated by the finger sliding on the tactile sensor and converts it into a digital signal. Then, the digital signal is encoded by the computer and converted into various control instructions for the hydraulic drive unit of the robot joint. Finally, dSPACE is used to convert the control instructions into multiple analog signals corresponding to the extension and retraction of the joint hydraulic drive unit, ultimately realizing the movement control of the robot's legs.

[0137] like Fig.17 The figure shows the operation demonstration of controlling the movement of the robot's legs through the tactile sensor and the corresponding output signals. When the finger slides on the tactile sensor, eight coded signals are generated, namely "100", "110", "010", "000", "001", "101", "011", and "111", which correspond to the eight control instructions of the robot's legs, namely "downward movement", "rightward movement", "leftward movement", "upward movement", "upper left movement", "lower right movement", "lower left movement", and "upper right movement". When there is no contact, the output voltage generated by the two electrodes of the tactile sensor is in the original state, and the robot's legs are in a stationary state. When the finger slides over the electrodes, the tactile sensor generates a set of coded signals, thereby controlling the robot's legs to perform the corresponding actions.

[0138] A second aspect of the present invention provides a method for preparing a double-helix tactile sensor, such as Fig.18 As shown, it includes the following steps:

[0139] S1. Cut the copper-plated PI film into a set shape and size.

[0140] S2. Prepare shielding copper 21 and double spiral electrodes on the copper-plated PI film to obtain an electrode layer.

[0141] S3, cutting a piece of PI film of the same size as the copper-plated PI film to obtain a covering layer.

[0142] S4. According to the positions of the contact points 22 and the chip resistor 25 set in different sliding directions of the double spiral electrode, laser cutting is used to process the touch holes and the chip resistor holes on the cover layer PI film.

[0143] S5, the covering layer PI film 3 is arranged on the electrode layer 2, the touch holes correspond to the contacts arranged on the double spiral electrodes, and the copper-plated PI film and the covering layer PI film 3 are pressed together by high temperature and high pressure, thereby forming a plurality of contacts.

[0144] S6. A gold plating layer is provided at the corresponding chip resistor hole on the copper-plated PI film, and the chip resistor 25 is welded to the terminal ends of the first electrode and the second electrode in the double spiral electrode.

[0145] S7, the copper-plated PI film, the double-helix electrode and the covering layer PI film together constitute a tactile sensor with a double-helix structure, thereby completing the production of the double-helix tactile sensor.

[0146] like Fig.19 and Fig. 20 As shown, in step S2, shielding copper and double spiral electrodes are prepared on the copper-plated PI film to obtain an electrode layer. The specific steps are as follows:

[0147] S21. Fix the copper-plated PI film on the pad, process positioning holes on the copper-plated PI film, and clean the surface of the copper-plated PI film to remove the oxide layer on the surface of the copper-plated layer.

[0148] S22, adhering the photoresist film to the surface of the copper layer in the copper-plated PI film, and aligning the film provided with a double spiral electrode pattern to the positioning hole on which the photoresist film has been adhered.

[0149] S23, transferring the pattern on the film to the photoresist film by optical imaging, and irradiating the film with an exposure light source to make the shielding copper and double spiral electrode patterns on the film sensitive to light.

[0150] S24, using a developer to remove the photoresist film in the unexposed area, so that the shielding copper in the unexposed area on the surface of the copper-plated PI film is revealed.

[0151] S25, retaining the photoresist film pattern at the exposed area, corroding the copper layer exposed after development with an etching solution, and retaining the area covered by the photoresist film.

[0152] S26. Use a stripping solution to remove the etched photoresist film to reveal the desired double spiral electrode and shielding copper pattern. At this time, a double spiral electrode is formed on the surface of the copper layer in the copper-plated PI film.

[0153] S27, complete the preparation of the double spiral electrode.

[0154] The embodiments described above are only descriptions of the preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A double helix tactile sensor, characterized in that: It includes a base film, an electrode layer and a covering layer, wherein the base film is provided with a copper foil; The electrode layer is arranged on the base film, and the electrode layer includes shielding copper plating, a double spiral electrode and a plurality of contacts arranged on the double spiral electrode. The electrode layer is provided with a shielding copper plating area and an electrode laying area, and the shielding copper plating is arranged at the shielding copper plating area; the double spiral electrode is arranged in the electrode laying area, and the intersection of the two diagonals of the base film is used as the electrode rotation center of the double spiral electrode. The double spiral electrode includes a first electrode and a second electrode, and the first electrode and the second electrode are both Archimedean spiral electrodes around the electrode rotation center, and the first electrode is located on the inner side of the second electrode, the first electrode and the second electrode are evenly distributed with a plurality of sliding directions around the electrode rotation center, and a plurality of contacts are arranged in each sliding direction, and each circle of the first electrode and the second electrode has and only has one contact in the same sliding direction, and the terminal ends of the first electrode and the second electrode are both provided with chip resistors, and both ends of the chip resistor are provided with grounding terminals; The covering layer has the same size as the base film, is provided with a plurality of elliptical holes, is arranged on the electrode layer, and the plurality of elliptical holes on the covering layer correspond to the plurality of contacts on the electrode layer.

2. The double helix tactile sensor according to claim 1, characterized in that: Since the peak value of the voltage signal across the patch resistor when the contact is touched is greater than the peak value of the voltage signal across the patch resistor when the contact is not touched, when the peak value of the voltage signal across the patch resistor of the first electrode is greater than the peak value of the voltage signal across the patch resistor of the second electrode, the first electrode generates a coding signal, otherwise the second electrode generates a coding signal; Assume that the coding signal generated when the contact point on the first electrode is touched is 0, and the coding signal generated when the contact point on the second electrode is touched is 1. When touched in different directions, different binary coding sequences can be generated in the corresponding directions to form coding signals, thereby identifying the sliding direction.

3. The double helix tactile sensor according to claim 1, characterized in that: The first electrode and the second electrode are both Archimedean spiral electrodes, and the polar coordinate expression of the axis of the first electrode is: ρ1=e+b·α / 2π Wherein, e represents the starting radius of the first electrode axis; b represents the axis density of the first electrode, and α represents the rotation angle of the electrode; The polar coordinate expression of the second electrode axis is: ρ2=c+d·α / 2π Wherein, c represents the starting radius of the axis of the second electrode; d represents the axis density of the second electrode.

4. The spiral tactile sensor according to claim 1, characterized in that: The base film and the covering layer are square, the width of the square is 116 mm, the width of the first electrode and the second electrode are both 1.5 mm, and the spacing between the first electrode and the shielding copper is 1 mm, the spacing between adjacent first and second electrodes is 0.5 mm, and the spacing between the inner spiral and the outer spiral in the double spiral electrode is 10 mm.

5. The spiral tactile sensor according to claim 1, characterized in that: When the contact point is not touched, the voltage signals across the chip resistors of the first electrode and the second electrode are: In the formula, R DS Represents the chip resistance on a single electrode. A, B, C, and D are represented by the following formulas, specifically: Where f represents the frequency of the coupled AC power supply, C sup1 Represents the coupling capacitance between the left end of the chip resistor of the first electrode and the power line, C sup2 Represents the coupling capacitance between the right end of the chip resistor of the second electrode and the power line, R iso Represents the resistance of the data acquisition device, V a Indicates the grid voltage, C iso Represents the ground capacitance of the data acquisition equipment; When the contact is touched, the signal generated by the coupled electric field of the human body is transmitted to the electrode corresponding to the touched contact, and the patch resistor on the touched electrode provides a symmetrical signal with positive and negative amplitudes. At this time, the voltage output signal of the patch resistor on the touched electrode is: In the formula, E, F, G, and H are respectively expressed by the following formulas: In the formula, C b Represents the coupling capacitance between the human body and the earth, C p Represents the coupling capacitance between the power line and the human body in the surrounding environment, R h Represents the equivalent resistance of the human body, C h Represents the equivalent capacitance of the human body, R q Indicates the contact resistance between the human body and the contact point.

6. The double helix tactile sensor according to claim 1, characterized in that: The expression for the number of sliding directions that can be detected by different electrodes on the electrode layer is: N=m α / 2π Wherein, m represents the number of electrodes provided on the electrode layer, and α represents the rotation angle of the electrode.

7. The double-helix tactile sensor according to claim 1, characterized in that: The base film and the cover layer are both rectangular PI films of set sizes.

8. The double helix tactile sensor according to claim 1, characterized in that: The rotation angle of the Archimedean spiral electrode is 6π.

9. A method for preparing a double-helix tactile sensor according to any one of claims 1 to 8, characterized in that: It includes the following steps: S1, cutting the copper-plated PI film into a set shape and size; S2, preparing shielding copper and double spiral electrodes on the copper-plated PI film to obtain an electrode layer; S3, cutting a piece of PI film of the same size as the copper-plated PI film to obtain a covering layer; S4, according to the contact points set in different sliding directions of the double spiral electrode and the position of the patch resistor, using laser cutting to process the touch holes and the patch resistor holes on the cover layer PI film; S5, placing the cover layer PI film on the electrode layer, the touch holes corresponding to the contacts arranged on the double spiral electrodes, and pressing the copper-plated PI film and the cover layer PI film together by high temperature and high pressure, thereby forming a plurality of contacts; S6, providing a gold plating layer at the corresponding chip resistor hole on the copper-plated PI film, and welding the chip resistor to the terminal ends of the first electrode and the second electrode in the double spiral electrode; S7, the copper-plated PI film, the double-helix electrode and the covering layer PI film together constitute a tactile sensor with a double-helix structure, thereby completing the production of the double-helix tactile sensor.

10. The preparation method according to claim 9, characterized in that: In step S2, shielding copper and double-helix electrodes are prepared on the copper-plated PI film to obtain an electrode layer, and the specific steps include: S21, fixing the copper-plated PI film on a pad, machining positioning holes on the copper-plated PI film, and cleaning the surface of the copper-plated PI film to remove the oxide layer on the surface of the copper-plated layer; S22, adhering a photoresist film to the surface of the copper layer in the copper-plated PI film, and aligning a film with a double spiral electrode pattern with the positioning hole on which the photoresist film has been adhered; S23, transferring the pattern on the film to the photoresist film by optical imaging, and irradiating the film with an exposure light source to make the shielding copper and double spiral electrode patterns on the film sensitive to light; S24, using a developer to remove the photoresist film in the unexposed area, so that the shielding copper in the unexposed area on the surface of the copper-plated PI film is revealed; S25, retaining the photoresist film pattern at the exposed area, corroding the copper layer exposed after development with an etching solution, and retaining the area covered by the photoresist film; S26, using a stripping solution to remove the etched photoresist film to reveal the desired double spiral electrode and shielding copper pattern, at which time a double spiral electrode is formed on the surface of the copper layer in the copper-plated PI film; S27, completing the preparation of the double spiral electrode.

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