A fingerpad tactile sensor capable of action recognition and three-dimensional force measurement and a sensing method thereof

Abstract

This invention discloses a fingertip tactile sensor and its sensing method capable of motion recognition and three-dimensional force measurement. The sensor comprises, from top to bottom, a stacked sensing electrode layer, a pressure-sensitive layer, and a grounding layer. The sensing electrode layer consists of four... x - y The device consists of four symmetrically distributed sensing electrodes arranged in pairs along a central axis. A common electrode forms the grounding layer, with its lower surface attached to the fingertips of the intelligent robotic arm. In the non-contact state, the four sensing electrodes are activated simultaneously or sequentially, forming three asymmetrical sensing units with the common electrode. This asymmetrical design effectively enables the recognition of robotic arm movements. In the contact state, the four sensing electrodes are activated sequentially, forming four sensing units with the common electrode. Three-dimensional pressure-shear force measurement is achieved by calculating the difference between two sensing units in the same measurement direction. This invention is used for non-contact movement recognition and three-dimensional force measurement after contact with an object during robotic arm operation, improving operational flexibility and accuracy.

Description

Technical Field

[0001] This invention belongs to the field of sensor technology, specifically relating to a fingertip tactile sensor and its sensing method that can realize motion recognition and three-dimensional force measurement. Background Technology

[0002] Currently, smart wearable electronic products have gradually evolved from early conceptual designs into a mature global industry, increasingly becoming a key growth driver in the global consumer technology and digital health sectors. As a disruptive technology, flexible electronic components are leading a profound transformation in smart wearable electronic products from traditional single-modal measurement to multi-functional and multi-modal applications, playing a crucial and irreplaceable role in human-computer interaction, healthcare, the Internet of Things, intelligent robotics, and other emerging fields. However, the following challenges also need to be overcome: 1) Action recognition in human-computer interaction requires comparing the differentiated responses of different sensing units to various hand gestures. However, traditional array-type flexible tactile units are often based on symmetrical structure design to achieve large-area distributed measurement. When the hand moves arbitrarily in the vertical or horizontal direction to make different hand gestures, the responses generated by the sensing units at different positions have only slight differences in timing and are easily affected by external signals. This is quite challenging for accurately recognizing various hand gestures. 2) Most tactile sensors are already able to accurately measure the magnitude of normal pressure, but in real human-computer interaction, contact is rarely an ideal vertical press. When an object slides, rolls, or has other actions that cause tangential friction with the skin, the direction and distribution of force change rapidly. The different stretching / compression states of the sensor unit lead to inconsistent sensitivity baselines, making calibration extremely difficult. The detection of three-dimensional pressure-shear force in different directions has always been another key focus for flexible sensors. Summary of the Invention

[0003] To address the aforementioned problems in existing technologies, this invention provides a fingertip tactile sensor and its sensing method capable of motion recognition and three-dimensional force measurement. This invention utilizes the controllable activation mode of an analog switch, enabling the sensing units within the sensor to form both asymmetrical and symmetrical distributions, which are respectively applied to motion recognition in non-contact states during robotic arm operation and to three-dimensional force measurement after contact with an object.

[0004] The technical solution adopted by this invention to solve its technical problem is: The first aspect of the present invention relates to a fingertip tactile sensor capable of motion recognition and three-dimensional force measurement, characterized in that it comprises a sensing electrode layer (1), a pressure-sensitive layer (2), and a grounding layer (3) stacked from top to bottom, wherein the lower surface of the sensing electrode layer (1) is in direct contact with the upper surface of the pressure-sensitive layer (2), the lower surface of the pressure-sensitive layer (2) is in direct contact with the upper surface of the grounding layer (3), and the lower surface of the grounding layer (3) is attached to the fingertip of the intelligent robotic hand; wherein: The sensing electrode layer (1) includes four along x - y The four sensing electrodes (4) are symmetrically distributed in pairs along the axis. The four sensing electrodes (4) are connected to the signal acquisition system through four analog switches. The signal acquisition system is connected to a microcomputer chip for control. The microcomputer chip controls the connection or disconnection of the four analog switches. The pressure-sensitive layer (2) is a porous ionized film with a pyramid array structure on the surface. The film material is a porous foam with a surface microstructure prepared based on polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP). The pressure-sensitive electrolyte material with a complete ion membrane covering the pore wall surface is obtained by immersion in an ionic liquid (EMImBF4). The grounding layer (3) includes a common electrode (7) whose area exactly covers the four sensing electrodes (4) on the sensing electrode layer (1).

[0005] Furthermore, the four sensing electrodes (4) include along... x Two rectangular induction electrodes (5) are arranged in the direction and along the direction. y Two dome-shaped sensing electrodes (6) are arranged in the direction of the two rectangular sensing electrodes (5), including the first rectangular sensing electrode. S 2 and the second rectangular induction electrode S 3. The two dome-shaped sensing electrodes (6) include the first dome-shaped sensing electrode. S 1 and second dome-shaped sensing electrodes S 4; First dome-shaped induction electrode S 1. Connect analog switch T1, first rectangular sensing electrode S 2. Connect analog switch T2, second rectangular sensing electrode S 3. Connect analog switch T3, second dome-shaped sensing electrode S 4. Connect analog switch T4; analog switches T1, T2, T3, and T4 are all connected to the signal acquisition system.

[0006] Furthermore, the method for preparing the pressure-sensitive layer (2) includes the following steps: S1. Dissolve the polyvinylidene fluoride-hexafluoropropylene copolymer in acetone at a concentration of 50 mg / mL and stir at 800 rpm and 55°C for 2 h. During stirring, add deionized water dropwise to the mixed solution at a volume ratio of 95:5 (acetone:deionized water = 95:5). S2. The obtained uniform solution is poured into an alloy mold with an inverted pyramid array structure and dried and cured in an oven at 80 ℃ for 3 hours to completely evaporate the acetone and deionized water in the material, thereby obtaining a porous foam substrate with surface microstructure. S3. The porous foam substrate is completely immersed in the ionic liquid and soaked in a vacuum environment for 24 hours. After a complete ionic film is formed on the surface of the pore wall, the excess ionic liquid is squeezed out to finally obtain the desired porous pressure-sensitive electrolyte material.

[0007] The second aspect of the present invention relates to a sensing method for realizing motion recognition and three-dimensional force measurement, characterized in that the sensing method employs the fingertip tactile sensor as described in any one of claims 1 to 3, which enables motion recognition and three-dimensional force measurement; two rectangular sensing electrodes (5) and two dome-shaped sensing electrodes (6) are connected to a signal acquisition system via four analog switches and controlled by a microcomputer chip to be in a connected or disconnected state; specifically including: When the sensing electrode layer installed on the sensor does not directly contact the surface of the object being measured (8), the sensor operates in a non-contact state and will connect to the second rectangular electrode. S 3 and the second dome electrode S The two analog switches T3 and T4 of 4 are configured as a temporary analog switch group, which are simultaneously connected or disconnected during measurement, and connected to the first rectangular electrode. S 2 and the first dome electrode S The two analog switches T1 and T2 are activated sequentially in a (1-1-2) manner, and their actual configuration with the common electrode is " The three asymmetric sensing units, when the intelligent robotic arm gradually approaches the object being measured, some of the divergent electric field lines that originally started from the four sensing electrodes and terminated at the common electrode turn towards the object being measured and flow towards the ground. As the distance approaches, the proportion of the turning electric field lines continuously increases, causing the capacitance of the three asymmetric sensing units to gradually decrease, reaching a minimum value when the object being measured and the sensor surface come into contact. Since the size and position of the three asymmetric sensing units are different, when the intelligent robotic arm moves arbitrarily in the vertical or horizontal direction to make various different gestures such as up, down, left, right, approach, away, and combinations thereof, the output response of the three asymmetric sensing units will have significant differences in the timing of the minimum value and the signal amplitude. Effectively extracting the feature differences between the signals can realize the recognition of the robotic arm's operation actions. When the sensing electrode layer installed on the sensor directly contacts the surface of the object being measured (8), the sensor works in the contact state. The porous pressure-sensitive layer with a pyramid array microstructure on the surface is continuously compressed as the pressure increases, which increases the contact area between the sensing electrode layer and the pressure-sensitive layer and between the pressure-sensitive layer and the ground layer. In fact, the positive and negative ions inside the pressure-sensitive layer, which is an ionized thin film, gradually converge at the upper and lower contact surfaces and form a double-layer interface capacitance at the contact interface, thereby achieving a measurement effect of enhanced sensitivity.

[0008] Furthermore, when the sensor is in contact mode, the analog switches connected to the four sensing electrodes are activated sequentially in a (1-1-1-1) configuration, forming a configuration with the common electrode as follows: The four symmetrical sensing units of the device undergo a uniform change in capacitance under normal pressure. The magnitude of the normal pressure can be measured by calculating the ratio of the sum of the relative changes in capacitance of the four symmetrical sensing units to the initial capacitance. x Under the action of directional shear force, the two rectangular sensing units in the middle produce opposite capacitance changes, while the dome-shaped sensing units on both sides produce consistent capacitance changes. y Under directional shear force, the dome-shaped sensing units on both sides produce opposite capacitance changes, while the two rectangular sensing units in the middle produce consistent capacitance changes. By calculating the ratio of the difference between the two sensing units in the same measurement direction to the initial capacitance, the capacitance can be determined. x - y Real-time measurement of directional shear force.

[0009] The technical concept of this invention is: This invention is attached to the fingertip of an intelligent robotic arm. During non-contact measurement, by controlling the activation sequence of four analog switches, three asymmetrical sensing units are formed inside the sensor. This asymmetrical design allows for more effective and accurate recognition of various movements, including upward, downward, leftward, rightward, closer, farther away, and combinations thereof. During contact measurement, the four analog switches are activated sequentially, forming four along... x - y By using symmetrically distributed sensing units along the axis, the normal pressure can be measured by calculating the ratio of the sum of the relative changes in capacitance of the four sensing units to the initial capacitance. Furthermore, by calculating the ratio of the difference between two sensing units in the same measurement direction to the initial capacitance, the normal pressure can be measured. x - y Real-time measurement of directional shear force.

[0010] Compared with the prior art, the beneficial effects of the present invention are reflected in: 1. This invention arranges four along... x - yThe structural design of the induction electrodes, which are symmetrically distributed in pairs along the axis, decouples the specific effects of pressure-shear force on different sensing units in the contact measurement stage, and realizes the measurement of three-dimensional pressure-shear force by using differential calculation.

[0011] 2. This invention adopts a controllable activation mode of analog switches and realizes an asymmetrical sensing unit design based on four symmetrical sensing electrodes. In the non-contact measurement stage, it enhances the response differences generated by different hand gestures and effectively realizes the accurate recognition of robotic arm operation actions. Attached Figure Description

[0012] Figure 1 This is an exploded view of the sensor structure of the present invention.

[0013] Figure 2 This is a schematic diagram of the distribution of sensing electrodes in the sensing electrode layer of the present invention.

[0014] Figure 3 This is a schematic diagram of the common electrode distribution of the grounding layer of the present invention.

[0015] Figure 4 This is a schematic diagram of the layout of three asymmetric sensing units used for gesture recognition.

[0016] Figure 5 This is a schematic diagram of the measurement principle of the sensor of this invention in a non-contact state.

[0017] Figure 6 This is a schematic diagram illustrating the measurement principle of the sensor of this invention under normal pressure.

[0018] Figure 7 This is the equivalent circuit diagram of the double-layer capacitance effect of the sensor of this invention under normal pressure.

[0019] Figure 8 This is a schematic diagram illustrating the measurement principle of the sensor of this invention under shear force.

[0020] In the diagram: 1. Induction electrode layer, 2. Varistor layer, 3. Grounding layer, 4. Induction electrode, 5. Rectangular electrode, 6. Dome electrode, 7. Common electrode, 8. Object under test. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0023] The present invention will now be described in detail with reference to the accompanying drawings and exemplary embodiments.

[0024] Example 1

[0025] This invention provides a fingertip tactile sensor capable of motion recognition and three-dimensional force measurement, such as... Figure 1 As shown, the sensor comprises, from top to bottom, a stacked sensing electrode layer 1, a pressure-sensitive layer 2, and a grounding layer 3. The lower surface of the sensing electrode layer 1 is in direct contact with the upper surface of the pressure-sensitive layer 2, and the lower surface of the pressure-sensitive layer 2 is in direct contact with the upper surface of the grounding layer 3. The lower surface of the grounding layer 3 is attached to the fingertip of the intelligent robotic hand.

[0026] like Figure 2 As shown, the sensing electrode layer 1 consists of four along... x - y The system consists of 4 induction electrodes symmetrically distributed in pairs along the axis, wherein along the axis... x Two rectangular sensing electrodes 5 are arranged in the direction, namely the first rectangular sensing electrode. S 2 and the second rectangular induction electrode S 3, along y Two dome-shaped sensing electrodes 6 are arranged in the direction, namely the first dome-shaped sensing electrode. S 1 and second dome-shaped sensing electrodes S 4. The four sensing electrodes 4 are connected to the signal acquisition system via four analog switches, and are controlled by a microcomputer chip to be in an on / off state. The first dome-shaped sensing electrode... S 1. Connect analog switch T1, first rectangular sensing electrode S 2. Connect analog switch T2, second rectangular sensing electrode S 3. Connect analog switch T3, second dome-shaped sensing electrode S 4. Connect analog switch T4.

[0027] like Figure 1 and Figure 3 As shown, the grounding layer 3 consists of a common electrode 7, the area of ​​which exactly covers the four sensing electrodes 4 on the sensing electrode layer 1.

[0028] like Figure 1 As shown, the pressure-sensitive layer 2 is a porous ionized thin film with a pyramidal array structure on its surface. The film material is a porous foam with a surface microstructure prepared based on polyvinylidene fluoride-hexafluoropropylene copolymer. By immersing it in an ionic liquid, a pressure-sensitive electrolyte material with a complete ion membrane covering the pore wall surface is obtained.

[0029] Specifically, the preparation method of pressure-sensitive layer 2 includes the following steps: First, polyvinylidene fluoride-hexafluoropropylene copolymer was dissolved in acetone at a concentration of 50 mg / mL and stirred at 800 rpm and 55°C for 2 h. During stirring, deionized water was added dropwise to the mixed solution at a volume ratio of 95:5 (acetone:deionized water). The resulting solution was then poured into an alloy mold with an inverted pyramid array structure and dried and cured in an oven at 80°C for 3 h to completely evaporate the acetone and deionized water in the material, resulting in a porous foam substrate with a surface microstructure. This high-porosity foam was then completely immersed in an ionic liquid and soaked in a vacuum environment for 24 h. After a complete ion membrane was formed on the pore wall surface, the excess ionic liquid was squeezed out, finally obtaining the desired porous pressure-sensitive electrolyte material.

[0030] Example 2

[0031] This invention discloses a sensing method for realizing motion recognition and three-dimensional force measurement. The sensing method employs a fingertip tactile sensor capable of realizing motion recognition and three-dimensional force measurement. The sensing method and measurement principle include: (1) such as Figure 1 As shown, the sensor is installed on the fingertip of the intelligent robotic arm. When the sensing electrode layer 1 on which the sensor is installed does not directly contact the surface of the object being measured 8, the sensor operates in a non-contact state and can complete the task of gesture recognition. The two analog switches T3 and T4 connecting the second rectangular electrode 5 and the second dome electrode 6 are set as a temporary analog switch group, which is simultaneously connected or disconnected during measurement. They are activated in sequence with the two analog switches T1 and T2 connecting the first dome electrode 6 and the first rectangular electrode 5 in a (1-1-2) manner. The actual configuration with the common electrode 7 is as follows: The three asymmetric sensing units, such as Figure 4 As shown, its capacitor is specifically named ( C s1 , C s2 , C s3-4 ): (1) in, ε s0 The initial relative permittivity of the pressure-sensitive layer before deformation occurs. ε 0 is the vacuum permittivity. d s0 The initial thickness of the pressure-sensitive layer before deformation occurs. A 1, A 2, A 3-4 It is the effective area of ​​the capacitance of the three asymmetric sensing units.

[0032] like Figure 5 As shown, when the intelligent robotic arm gradually approaches the object under test 8, some of the divergent electric field lines that originally started from the four sensing electrodes 4 and terminated at the common electrode 7 turned towards the object under test 8 and flowed towards the ground. These electric field lines that changed direction caused the sensing electrodes 4 and the object under test 8 to form three additional equivalent capacitances, specifically named ( C obj1 , C obj2 , C obj3-4 ): (2) In the formula, d obj The distance of the measured object 8 to the sensor.

[0033] Three asymmetric sensing units are connected in parallel with their corresponding equivalent capacitances, among which C s1 and C obj1 in parallel, C s2 and C obj2 in parallel, C s3-4 and C obj3-4 Parallel connection, in practice, results in the measured capacitance being expressed as ( C mea1 , C mea2 , C mea3-4 ): (3) As the distance decreases, the proportion of the electric field lines that change direction continuously increases, causing the capacitance of the three asymmetric sensing units to ( C s1 , C s2 , C s3-4 The three equivalent capacitances gradually decrease. C obj1 , C obj2 , C obj3-4 The increase in capacitance actually leads to an increase in the measured capacitance. C mea1 , C mea2 , C mea3-4The value decreases and reaches its minimum when the measured object 8 comes into contact with the sensor surface. Since the size and position of the three asymmetric sensing units are different, when the hand moves arbitrarily in the vertical or horizontal direction to make various different gestures such as up, down, left, right, closer, farther away and their combinations, the output response of the three asymmetric sensing units will have significant differences in the timing of the minimum value and the signal amplitude compared with the traditional non-contact sensor based on the symmetrical structure design. This can more effectively and accurately realize the accurate recognition of the robot's operation actions.

[0034] (2) For example Figure 6 and Figure 7 As shown, when the sensing electrode layer 1 installed on the sensor directly contacts the surface of the object being measured 8, the sensor operates in a contact state. The distance between the object being measured 8 and the sensing electrode 4 no longer changes. The change in the measured capacitance is mainly determined by the capacitance change of the sensing unit between the sensing electrode 4 and the common electrode 7. At this time, the porous pressure-sensitive layer 2, whose surface is a pyramid array microstructure, is continuously compressed as the pressure increases, which increases the contact area between the sensing electrode layer 1 and the pressure-sensitive layer 2, and between the pressure-sensitive layer 2 and the ground layer 3. In fact, the positive and negative ions inside the pressure-sensitive layer 2, which is an ionized thin film, gradually converge at the upper and lower contact surfaces and form a double-layer interface capacitance at the contact interface. C EDL-t , C EDL-b Specifically, it can be expressed as: (4) in, η A This is the ratio of the roughness of the pressure-sensitive layer 2 surface to that of an ideal smooth surface. Φ These are interfacial properties related to the electrolyte and electrode layer. l The thickness of the Helmholtz layer. ε Where is the dielectric constant. C i This refers to the ion concentration. Surface potential, T It is the ambient temperature. A The contact area between the electrode and the pressure-sensitive layer 2 is denoted as , where η A and Φ The product represents the capacitance per unit area. UAC .

[0035] Double-layer capacitor ( C EDL-t , C EDL-bThe capacitance density reaches the level of µF / cm², which is 3 to 5 orders of magnitude higher than that of the traditional capacitive sensor described by Equation (1). Therefore, Equation (1) is no longer applicable to calculate the capacitance between the sensing electrode 4 and the common electrode 7, and the resulting measurement results have a significantly enhanced sensitivity.

[0036] Simultaneously, in order to achieve three-dimensional pressure-shear force measurement, the analog switch connected to the four sensing electrodes 4 is activated sequentially, forming a configuration with the common electrode 7 as " The four symmetrical sensing units, along x The direction forms two rectangular sensing units ( C x1 , C x2 ),along y The direction forms two dome-shaped sensing units ( C y1 , C y2 Its specific size is expressed as: (5) Under normal pressure, the capacitance of the four sensing units changes uniformly. The magnitude of the normal pressure can be measured by calculating the ratio of the sum of the relative changes in capacitance of the four sensing units to the initial capacitance. (6) in, P z For normal pressure, K z This is the correlation coefficient between the change in capacitance and the normal pressure. In actual measurement, the fitting curve should be obtained through calibration data.

[0037] x Under the action of directional shear force, the two rectangular sensing units in the middle ( C x1 , C x2 ) produces opposite capacitance changes, and the dome-shaped sensing units on both sides ( C y1 , C y2 This produces a consistent change in capacitance. y Under the action of directional shear force, the dome-shaped sensing units on both sides ( C y1 , C y2 The two rectangular sensing units in the middle produce opposite capacitance changes. C x1 , C x2This generates a consistent capacitance change. By calculating the ratio of the difference between the two sensing units in the same measurement direction to the initial capacitance, the signal can be controlled. x - y Real-time measurement of directional shear force: (7) (8) in, P x and P y It is a tangential shear force. K x and K y These are the correlation coefficients between the change in capacitance and the tangential shear force, respectively. In actual measurement, the fitting curve should also be obtained through calibration data.

[0038] Finally, it should be noted that the above embodiments and descriptions are only used to illustrate the technical solutions of the present invention and not to limit it. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the disclosure of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the protection scope of the claims of the present invention.

Claims

1. A fingertip tactile sensor capable of motion recognition and three-dimensional force measurement, characterized in that, The device comprises a sensing electrode layer (1), a pressure-sensitive layer (2), and a grounding layer (3) stacked from top to bottom. The lower surface of the sensing electrode layer (1) is in direct contact with the upper surface of the pressure-sensitive layer (2), and the lower surface of the pressure-sensitive layer (2) is in direct contact with the upper surface of the grounding layer (3). The lower surface of the grounding layer (3) is attached to the fingertip of the intelligent robotic hand. The sensing electrode layer (1) includes four along x - y The four sensing electrodes (4) are symmetrically distributed in pairs along the axis. The four sensing electrodes (4) are connected to the signal acquisition system through four analog switches. The signal acquisition system is connected to a microcomputer chip for control. The microcomputer chip controls the connection or disconnection of the four analog switches. The pressure-sensitive layer (2) is a porous ionized thin film with a pyramid array structure on the surface. The film material is a porous foam with a surface microstructure prepared based on polyvinylidene fluoride-hexafluoropropylene copolymer, and a pressure-sensitive electrolyte material with a complete ion membrane covering the pore wall surface is obtained by immersion in ionic liquid. The grounding layer (3) includes a common electrode (7) whose area exactly covers the four sensing electrodes (4) on the sensing electrode layer (1).

2. The fingertip tactile sensor capable of motion recognition and three-dimensional force measurement as described in claim 1, characterized in that, The four sensing electrodes (4) include along x Two rectangular induction electrodes (5) are arranged in the direction and along the direction. y Two dome-shaped sensing electrodes (6) are arranged in the direction of the two rectangular sensing electrodes (5), including the first rectangular sensing electrode. S 2 and the second rectangular induction electrode S 3. The two dome-shaped sensing electrodes (6) include the first dome-shaped sensing electrode. S 1 and second dome-shaped sensing electrodes S 4; First dome-shaped induction electrode S 1. Connect analog switch T1, first rectangular sensing electrode S 2. Connect analog switch T2, second rectangular sensing electrode S 3. Connect analog switch T3, second dome-shaped sensing electrode S 4. Connect analog switch T4; analog switches T1, T2, T3, and T4 are all connected to the signal acquisition system.

3. A fingertip tactile sensor capable of motion recognition and three-dimensional force measurement as described in claim 1, characterized in that, The method for preparing the pressure-sensitive layer (2) includes the following steps: S1. First, dissolve the polyvinylidene fluoride-hexafluoropropylene copolymer in acetone at a concentration of 50 mg / mL, and stir at 800 rpm and 55°C for 2 h. During the stirring process, add deionized water dropwise to the mixed solution at a volume ratio of 95:5 (acetone:deionized water = 95:5). S2. The obtained uniform solution is poured into an alloy mold with an inverted pyramid array structure and dried and cured in an oven at 80 ℃ for 3 hours to completely evaporate the acetone and deionized water in the material, thereby obtaining a porous foam substrate with surface microstructure. S3. The porous foam substrate is completely immersed in the ionic liquid and soaked in a vacuum environment for 24 hours. After a complete ionic film is formed on the surface of the pore wall, the excess ionic liquid is squeezed out to finally obtain the desired porous pressure-sensitive electrolyte material.

4. A sensing method for realizing motion recognition and three-dimensional force measurement, characterized in that, The sensing method employs the fingertip tactile sensor described in any one of claims 1 to 3, which enables motion recognition and three-dimensional force measurement. Two rectangular sensing electrodes (5) and two dome-shaped sensing electrodes (6) are connected to the signal acquisition system via four analog switches and controlled by a microcomputer chip to be in a connected or disconnected state. Specifically, it includes: When the sensing electrode layer installed on the sensor does not directly contact the surface of the object being measured (8), the sensor operates in a non-contact state and will connect to the second rectangular electrode. S 3 and the second dome electrode S The two analog switches T3 and T4 of 4 are configured as a temporary analog switch group, which are simultaneously connected or disconnected during measurement, and connected to the first rectangular electrode. S 2 and the first dome electrode S The two analog switches T1 and T2 are activated sequentially in a (1-1-2) manner, and their actual configuration with the common electrode is as follows: The three asymmetric sensing units, when the intelligent robotic arm gradually approaches the object being measured, some of the divergent electric field lines that originally started from the four sensing electrodes and terminated at the common electrode turn towards the object being measured and flow towards the ground. As the distance approaches, the proportion of the turning electric field lines continuously increases, causing the capacitance of the three asymmetric sensing units to gradually decrease, reaching a minimum value when the object being measured and the sensor surface come into contact. Since the size and position of the three asymmetric sensing units are different, when the intelligent robotic arm moves arbitrarily in the vertical or horizontal direction to make various different gestures such as up, down, left, right, approach, away, and combinations thereof, the output response of the three asymmetric sensing units will have significant differences in the timing of the minimum value and the signal amplitude. Effectively extracting the feature differences between the signals can realize the recognition of the robotic arm's operation actions. When the sensing electrode layer installed on the sensor directly contacts the surface of the object being measured (8), the sensor works in the contact state. The porous pressure-sensitive layer with a pyramid array microstructure on the surface is continuously compressed as the pressure increases, which increases the contact area between the sensing electrode layer and the pressure-sensitive layer and between the pressure-sensitive layer and the ground layer. In fact, the positive and negative ions inside the pressure-sensitive layer, which is an ionized thin film, gradually converge at the upper and lower contact surfaces and form a double-layer interface capacitance at the contact interface, thereby achieving a measurement effect of enhanced sensitivity.

5. The sensing method for realizing motion recognition and three-dimensional force measurement as described in claim 4, characterized in that, When the sensor is in contact mode, the analog switches connected to the four sensing electrodes are activated sequentially in a (1-1-1-1) configuration, forming a configuration with the common electrode as follows: The four symmetrical sensing units of the device undergo a uniform change in capacitance under normal pressure. The magnitude of the normal pressure can be measured by calculating the ratio of the sum of the relative changes in capacitance of the four symmetrical sensing units to the initial capacitance. x Under the action of directional shear force, the two rectangular sensing units in the middle produce opposite capacitance changes, while the dome-shaped sensing units on both sides produce consistent capacitance changes. y Under directional shear force, the dome-shaped sensing units on both sides produce opposite capacitance changes, while the two rectangular sensing units in the middle produce consistent capacitance changes. By calculating the ratio of the difference between the two sensing units in the same measurement direction to the initial capacitance, the capacitance can be determined. x - y Real-time measurement of directional shear force.

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