Three-dimensional force sensor with high spatial resolution, electronic skin and robot

Abstract

The utility model relates to a three-dimensional force sensor with high spatial resolution, an electronic skin and a robot. The three-dimensional force sensor comprises a measuring branch, a processing module, a switch array and a sensing unit, the sensing unit is provided with a flexible body, a three-dimensional force detection assembly which generates light intensity, magnetic flux, resistance or capacitance changes when being stressed and deformed is arranged in an area included by the flexible body, and the three-dimensional force detection assembly serves as a minimum mechanical sensing unit; at least two measuring points are distributed on the flexible body of each sensing unit, and the measuring points are arranged to form a sensing array of the sensing unit and used for detecting the spatial position of a stress action point of the flexible body of the corresponding sensing unit; the measurement branch is coupled with the three-dimensional force detection assembly to obtain first-class detection data, and is respectively coupled with each measurement point through the switch array to obtain second-class detection data; and the processing module is coupled with the measurement branch, outputs a three-dimensional force signal according to the first type of detection data and outputs a spatial resolution signal according to the second type of detection data.

Description

Technical Field

[0001] This utility model relates to robot tactile perception, and more particularly to a three-dimensional force sensor with high spatial resolution, electronic skin, and robot. Background Technology

[0002] In real-world environments, the contact forces between objects and robots typically come from multiple directions, such as pressing and shearing. Machine tactile sensing requires three-dimensional force detection to fully reflect the interaction state.

[0003] Currently, three-dimensional force-sensitive units, or three-dimensional force detection components, used to realize tactile sensing on robot surfaces include capacitive, piezoresistive, photoelectric, electromagnetic, and multimodal types. Each three-dimensional force-sensitive unit is the smallest unit capable of independently measuring three-dimensional forces. To meet the high spatial resolution requirements of robot surface tactile sensing, current mainstream efforts focus on making the smallest unit smaller and smaller, forming a denser lattice by arranging multiple units, thereby improving the spatial resolution of the perception.

[0004] CN103743503B discloses a flexible three-dimensional force tactile sensor, in which multiple three-dimensional force-sensitive units are arranged to form a sensitive array. Each three-dimensional force-sensitive unit integrates a vertically arranged force-sensitive strain gauge and four sets of vertically arranged sensing capacitors, which are sensitive to vertical normal force and horizontal tangential force, respectively.

[0005] CN110082010A discloses a flexible tactile sensor array, in which each three-dimensional force-sensitive unit is realized by four piezoresistive protrusions, and the three-dimensional force-sensitive units are arranged to form an array.

[0006] CN117030070A discloses a flexible array tactile sensor, in which each three-dimensional force-sensitive unit is composed of an upper electrode and four lower electrodes to form an array of multiple sensing units.

[0007] CN216206640U discloses a composite flexible sensing array, in which a hemisphere and four pressure-sensitive elements underneath form a three-dimensional force-sensitive unit, and the three-dimensional force-sensitive units form an array.

[0008] Our previously proposed touch sensor (see CN209820667U) uses a flexible hemispherical protrusion as the upper electrode, which, together with four lower electrodes, forms the smallest three-dimensional force-sensitive unit. Each three-dimensional force-sensitive unit forms an array, employing the same concept.

[0009] While this approach has made significant progress with the miniaturization of three-dimensional force-sensitive units, the spatial resolution of tactile arrays (i.e., the smallest number of units per unit area capable of independently sensing three-dimensional forces) remains difficult to achieve at an ideal level due to technological limitations, multiple contradictions between physical principles and practical applications. Key factors include: when the size of the force-sensitive unit shrinks to the millimeter or even micrometer scale, the stiffness of the mechanical structure increases, leading to a weakening of the deformation signal of small forces and a decrease in the signal-to-noise ratio; after the miniaturization of the three-dimensional force-sensing unit, the enhanced mechanical coupling effect in adjacent directions causes unexpected deformation; and physical limitations in materials and manufacturing. Utility Model Content

[0010] To address the shortcomings of existing technologies, a three-dimensional force sensor is proposed.

[0011] As a solution, the three-dimensional force sensor provided by this utility model includes a measurement branch, a processing module, a switch array, and at least one sensing unit. Each sensing unit has a flexible body for contacting external objects. Within the area contained in the flexible body, a three-dimensional force detection component is disposed to generate changes in light intensity, magnetic flux, resistance, or capacitance due to force deformation. The three-dimensional force detection component serves as the smallest mechanical sensing unit in the sensor and is used to independently detect three-dimensional forces. Each sensing unit's flexible body has at least two measurement points distributed among them. These measurement points are arranged at different positions on the corresponding flexible body to form a sensing array of the sensing unit. Each measurement point in the sensing array is used to detect the spatial position of the force application point on the corresponding sensing unit's flexible body. The measurement branch couples the three-dimensional force detection component to obtain a first type of detection data, and the switch array couples each measurement point to obtain a second type of detection data. The processing module couples the measurement branch and is used to output a three-dimensional force signal based on the first type of detection data and a spatially resolved signal based on the second type of detection data.

[0012] The three-dimensional force sensor provided by this utility model also includes the following auxiliary solutions:

[0013] Each measurement point includes a first electrode and a second electrode stacked vertically, with the projection of the first electrode relative to the second electrode covering at least a portion of the area of ​​the second electrode. The measurement branch includes a capacitance-to-digital conversion circuit, which couples the first and second electrodes at each point via a switch array to acquire the mutual capacitance between the first and second electrodes at each point. The first and second electrodes serve as capacitance sensing electrodes. Alternatively, each measurement point may have a piezoelectric material and first and second electrodes disposed on the upper and lower surfaces of the piezoelectric material. The piezoelectric material at each measurement point may be integral or separate. The first and second electrodes serve as signal output electrodes for the corresponding piezoelectric material at each point. The measurement branch includes a piezoelectric measurement circuit, which couples the first and second electrodes at each point via a switch array to acquire the electrical signal between the first and second electrodes at each point. The piezoelectric measurement circuit includes a charge amplifier to amplify the electrical signal. Furthermore, the projection of the first electrode relative to the second electrode at least covers a portion of the area of ​​the second electrode; the measurement branch includes a capacitance-to-digital conversion circuit, which couples the first and second electrodes at each point via a switch array to acquire the mutual capacitance between the first and second electrodes at each point. The first and second electrodes serve as multiplexed electrodes for both capacitance sensing and piezoelectric material signal output. Further, each measurement point includes at least a first electrode, and the measurement branch includes a capacitance-to-digital conversion circuit, which couples the first electrode at each point via a switch array to acquire the self-capacitance of the first electrode and / or the mutual capacitance between the first electrodes at two points. The first electrode serves at least as a proximity detection electrode. Alternatively, each measurement point is provided with a piezoresistive material, and the piezoresistive material at each measurement point is provided with a corresponding first and second electrode, which are respectively disposed on the upper and lower surfaces of the piezoresistive material. The first and second electrodes serve as signal output electrodes for the piezoresistive material at the corresponding point; the measurement branch includes a piezoresistive measurement circuit, which couples the first and second electrodes at each point via a switch array to acquire the electrical signal between the first and second electrodes at each point when an object contacts it. Furthermore, each measurement point is provided with a piezoresistive material, and each measurement point's piezoresistive material is provided with a first electrode and a second electrode. The first electrode and the second electrode are coplanarly disposed on the piezoresistive material, and the first electrode and the second electrode serve as signal output electrodes of the piezoresistive material at the corresponding point. The measurement branch includes a piezoresistive measurement circuit, which couples the first electrode and the second electrode at each point through a switch array to acquire the electrical signal between the first electrode and the second electrode at each point when the object is in contact.Furthermore, the piezoresistive material between each measurement point or between the aggregated areas formed by several measurement points forms an insulating gap; the second electrode serves as the near-ground end of the measurement point, and a selector switch is connected in series between the second electrode and the ground; the measurement branch includes a capacitance-to-digital conversion circuit, which is coupled to the first electrode of each point through a switch array to obtain the self-capacitance of the first electrode and / or the mutual capacitance between two mutually insulated first electrodes when an object approaches, and the first electrode serves as the proximity detection electrode.

[0014] In this design, the first electrode at each measurement point is a point electrode, and these point electrodes are arranged in an array. The second electrode at each measurement point is integrally formed into a common electrode, with the point electrodes located above the common electrode. Furthermore, the three-dimensional force detection component is based on capacitive three-dimensional force detection; the second electrode serves as a combined electrode for both contact detection (common electrode) and shielding (shielding electrode) of the three-dimensional force detection component. Alternatively, both the first and second electrodes at each measurement point are point electrodes, arranged in an array within the same layer. Or, both the first and second electrodes are strip electrodes, with the first electrodes arranged at a certain spacing laterally and the second electrodes arranged at a certain spacing longitudinally, forming a staggered matrix in the vertical projection direction, with the staggered positions serving as measurement points.

[0015] The flexible body has a downward-protruding flexible structure on its inner side, and the surface of the flexible structure is curved. When the flexible body is subjected to external force, the curved surface of the flexible structure changes, resulting in changes in light intensity, magnetic flux, resistance or capacitance.

[0016] Furthermore, the three-dimensional force detection component includes a magnetic source for actively generating a magnetic field and at least three magnetic field measurement electronic components. The magnetic source is embedded in the flexible structure, and each magnetic field measurement electronic component is located below the flexible structure and distributed around its periphery. The magnetic field measurement electronic components are in direct or indirect contact with the curved surface of the flexible structure. The deformation of the flexible body under external force causes the curved surface of the flexible structure to change the direct or indirect contact area with the magnetic field measurement electronic components. The measurement branch includes an analog-to-digital conversion circuit, and the processing module is coupled to each magnetic field measurement electronic component via the analog-to-digital conversion circuit to output a three-dimensional force signal based on the magnetic flux of the magnetic field measurement electronic components changed by the deformation of the flexible structure. Alternatively, the flexible body may contain a light-sealed region, with the flexible body serving as a partial boundary of the light-sealed region. The three-dimensional force detection component includes a flexible structure protruding downwards from the inside of the flexible body, a light-emitting channel located within the light-sealed region below the flexible structure, and at least three photosensitive electronic elements located within the light-sealed region for receiving light reflected from the flexible structure. The flexible structure is made of opaque material, and the photosensitive electronic elements are distributed around the periphery of the flexible structure. The light-emitting channel is used to emit light directed towards the flexible structure through a light source. The flexible structure deforms under external pressure, changing the area of ​​obstruction of the light passing through the light-emitting channel. The measurement branch includes an analog-to-digital conversion circuit, and the processing module is coupled to each photosensitive electronic element via the analog-to-digital conversion circuit to output a three-dimensional force signal based on the change in reflected light caused by the deformation of the flexible structure. Alternatively, the three-dimensional force detection component includes an upper electrode disposed on a flexible structure and at least three lower electrodes located below the upper electrode; the upper electrode is a curved elastic electrode, an insulating layer is disposed between the upper electrode and the lower electrodes, and each lower electrode is distributed around the periphery of the flexible structure, with the downward projection of the upper electrode covering at least a portion of the area of ​​each lower electrode; the flexible multifunctional layer deforms under external force, causing the upper electrode to change the indirect contact area with the insulating layer; the measurement branch includes a capacitance-to-digital conversion circuit, which is coupled to the upper electrode and each lower electrode respectively, for obtaining the capacitance between the upper electrode and each lower electrode; the processing module is coupled to the capacitance-to-digital conversion circuit, for outputting a three-dimensional force signal based on the capacitance between the upper electrode and each lower electrode changed by the deformation of the flexible structure.

[0017] An electronic skin is also provided, including the aforementioned three-dimensional force sensor.

[0018] A robot is also provided, including the aforementioned electronic skin.

[0019] The sensor structure of this utility model, as the smallest unit, enables independent measurement of three-dimensional force. By means of multiple points distributed on its flexible body, an array of sensing force positions is formed, which compensates for the spatial resolution of the normal direction. The sensing array takes into account both the sensitivity of three-dimensional force detection and a high level of spatial resolution. Attached Figure Description

[0020] Figure 1 A schematic diagram of a capacitor array is given, showing the upper and lower electrodes arranged in rows and columns to form a matrix.

[0021] Figure 2 A schematic diagram of a piezoelectric array with point electrodes for the upper and lower electrodes is provided.

[0022] Figure 3a A schematic diagram of the electric field of the first electrode as a self-capacitance is given; Figure 3b A schematic diagram of the planar mutual capacitance electric field between the first electrode at two points is given.

[0023] Figure 4a A schematic diagram of the upper and lower electrodes of the piezoresistive array is given; Figure 4b A schematic diagram of the left and right electrodes on the top surface of the piezoresistive array is given;

[0024] Figure 5 Provide a circuit connection diagram for the piezoresistive array;

[0025] Figure 6 A schematic diagram of the upper point electrode and the lower common electrode is given;

[0026] Figure 7a Provide a stereoscopic view of the Hall effect 3D sensor; Figure 7b A schematic diagram of the internal structure of a Hall effect 3D sensor is provided. Figure 7c A schematic diagram of the convex curved surface of a Hall effect 3D sensor is given;

[0027] Figure 8a Provide a stereoscopic view of the photoelectric three-dimensional sensor; Figure 8b A schematic diagram of the convex curved surface of a photoelectric three-dimensional sensor is given; Figure 8c An internal cross-sectional view of a photoelectric three-dimensional sensor is given;

[0028] Figure 9a An exploded view of the structure of a capacitive three-dimensional sensor is given. Figure 9b A stereoscopic view of a capacitive three-dimensional sensor is provided. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0030] See Figure 7a , Figure 7b , Figure 8aAs shown in Figure 9, the three-dimensional force sensor includes a measurement branch, a processing module, a switch array, and at least one sensing unit. Each sensing unit has a flexible body 100 for contacting external objects. Within the area of ​​the flexible body 100, a three-dimensional force detection component is disposed, which generates changes in light intensity, magnetic flux, resistance, or capacitance due to force deformation. The three-dimensional force detection component serves as the smallest mechanical sensing unit in the sensor, independently detecting three-dimensional forces. At least two measurement points 200 are distributed on the flexible body 100 of each sensing unit. These measurement points 200 are arranged at different positions on the corresponding flexible body 100 to form a sensing array 300 for the sensing unit. Each measurement point 200 in the sensing array 300 is used to detect the spatial position of the force application point on the corresponding sensing unit's flexible body 100. The measurement branch couples the three-dimensional force detection component to obtain a first type of detection data, and the switch array couples each measurement point 200 to obtain a second type of detection data. The processing module couples the measurement branch and outputs a three-dimensional force signal based on the first type of detection data and a spatially resolved signal based on the second type of detection data.

[0031] For machine surface tactile sensing, pursuing high spatial resolution in the normal direction is crucial, such as allowing mechanical fingers to respond to the force points of sharp objects or needle pricks. However, pursuing high spatial resolution in the tangential direction is not very meaningful. Even the human hand, which has evolved biologically, does not require excessively high spatial recognition of friction or shear effects. Unnecessarily pursuing high spatial resolution in all three directions only leads to a more complex sensor array structure and makes it difficult to overcome the spatial resolution challenges of already sufficiently miniaturized three-dimensional force-sensitive unit arrays. Therefore, in the sensor structure of this invention, the three-dimensional force detection component, as the smallest unit, achieves independent measurement of three-dimensional forces. By utilizing multi-point measurements distributed on its flexible body 100 to form an array sensing the force location, it compensates for the spatial resolution in the normal direction. The sensing array 300 balances the sensitivity of three-dimensional force detection with a high level of spatial resolution.

[0032] 1.1 Capacitive sensing array 300

[0033] See Figure 1As an implementation of the sensing array 300 on the flexible body 100, a first optional embodiment involves setting a first electrode 210 and a second electrode 220 stacked vertically at the measurement point 200. The first electrode 210 and the second electrode 220 are separated and supported by a dielectric thin film 410, and the projection of the first electrode 210 relative to the second electrode 220 at least covers a portion of the area of ​​the second electrode 220. The measurement branch includes a capacitance-to-digital converter (CDC) circuit, which uses a Δ-Σ modulation method to convert the measured capacitance value into a digital value by repeatedly charging and discharging the measured capacitance and comparing it with the measured capacitance, thereby improving the capacitance measurement sensitivity to the 1ff level. The capacitance-to-digital converter circuit couples the first electrode 210 and the second electrode 220 at each point through a switch array to obtain the parallel plate mutual capacitance between the first electrode 210 and the second electrode 220 at each point. The first electrode 210 and the second electrode 220 serve as capacitance sensing electrodes. When the measurement point 200 is subjected to force, changes in the distance between the first electrode 210 and the second electrode 220 directly cause changes in capacitance, resulting in good linear response and insensitivity to temperature and humidity.

[0034] 1.2 Piezoelectric sensing array 300

[0035] See Figure 2 As a second optional implementation of the sensing array 300, each measurement point 200 is provided with a piezoelectric material and a first electrode 210 and a second electrode 220 respectively disposed on the upper and lower surfaces of the piezoelectric material. The piezoelectric material between each measurement point 200 is integrally formed into a piezoelectric thin film 420, which facilitates engineering manufacturing. The first electrode 210 and the second electrode 220 serve as signal output electrodes of the piezoelectric material at the corresponding point. The measurement branch includes a piezoelectric measurement circuit, which is coupled to the first electrode 210 and the second electrode 220 at each point through a switch array to acquire the electrical signal between the first electrode 210 and the second electrode 220 at each point. The piezoelectric measurement circuit includes a charge amplifier to amplify the electrical signal. The piezoelectric material is sensitive to vibration, has a fast response speed, a thickness of 7-110 micrometers, and can be divided into 1mm segments. 2 Piezoelectric materials offer significant advantages for achieving higher spatial resolution, but are susceptible to temperature interference and are not well-suited for detecting static forces. They possess high insulation strength and a relative permittivity of 10. -15Suitable for use as a dielectric, the signal output electrodes can be reused to form a capacitive sensor. Capacitors have good detection of static forces, forming a complementary relationship. Specifically, in the piezoelectric method, the projection of the first electrode 210 relative to the second electrode 220 at each measurement point 200 is set to at least cover a portion of the area of ​​the second electrode 220. The capacitance digital conversion circuit of the measurement branch is coupled to the first electrode 210 and the second electrode 220 at each point through a switch array to obtain the parallel plate mutual capacitance between the first electrode 210 and the second electrode 220 at each point. The first electrode 210 and the second electrode 220 serve as reused electrodes for both the capacitive sensing electrode and the signal output electrode of the piezoelectric material. During dynamic pressure application, the spatial position of the force point is sensed based on the change in the piezoelectric signal. When the system is statically stable, the system switches to parallel plate capacitance for force sensing.

[0036] When spatial position is detected using the above-mentioned capacitive sensing array 300, piezoelectric sensing array 300 or other methods, each measurement point 200 has at least a first electrode 210, which serves as at least a proximity detection electrode. The capacitance-to-digital conversion circuit is coupled to the first electrode 210 of each point through a switch array to obtain the self-capacitance of the first electrode 210 and / or the mutual capacitance of the first electrodes 210 between two points. Figure 3a A schematic diagram of the electric field of the first electrode as a self-capacitance is given; Figure 3b A schematic diagram of the planar mutual capacitance electric field of the first electrode between two points is given. When the three-dimensional force detection component does not detect pressure, the first electrode 210 is set to non-contact capacitive sensing. Multiple first electrodes 210 can be combined into one self-capacitive electrode or two mutual capacitance electrodes to increase the electrode area for capacitive proximity detection, thus achieving non-contact object detection. When using mutual capacitance, different objects have different dielectric constants, which produce different capacitance changes when entering the planar mutual capacitance electric field, further enabling material identification. When an object is detected approaching, the first electrode 210 switches to capacitive contact detection. Each measurement point 200 collects the self-capacitance of the first electrode 210 at its location or the mutual capacitance of the first electrode 210 between two points. Object contact causes a sudden change in the self-capacitance of the first electrode 210 and / or the mutual capacitance of the first electrode 210 between two points, realizing contact position measurement and sensing the point of force application.

[0037] Piezoelectric materials such as PVDF exhibit strong pyroelectric and dielectric effects, enabling them to sense temperature changes. Based on the aforementioned piezoelectric array in the sensing array 300, upon detecting object contact, the piezoelectric signals from adjacent non-pressurized points or the mutual capacitance signals of the parallel plates are acquired. If there is a temperature difference between the contacting object and the sensor, the piezoelectric materials at adjacent non-pressurized points generate charge due to radiation and conduction effects, or their dielectric constant changes with temperature. The object temperature is inferred from the charge changes or mutual capacitance changes at adjacent non-pressurized points. Further, the piezoelectric signal at the pressurized point can be acquired to determine the pressure at that point. The pressure at the pressurized point is then corrected based on the inferred object temperature, such as by using a mapping relationship to determine a correction coefficient based on stability. Alternatively, in a simpler case, given the piezoelectric signals from the pressurized point and adjacent non-pressurized points, the difference between the piezoelectric signals from the pressurized point and the adjacent non-pressurized points can be used to characterize the normal pressure. The normal force measured based on the piezoelectric material can be used as a verification of the normal force of the three-dimensional force detection component.

[0038] 1.3 Piezoresistive Sensing Array 300

[0039] See Figure 4a , Figure 4b As a third optional implementation of the sensing array 300, each measurement point 200 is provided with a piezoresistive material 430, and the layer containing each piezoresistive material 430 is called a piezoresistive layer 440. A first electrode 210 and a second electrode 220 are correspondingly disposed on the piezoresistive material 430 at each measurement point 200. For the piezoresistive material 430, the first electrode 210 can be disposed on the top surface and the second electrode 220 on the bottom surface, such as... Figure 4a Alternatively, the first electrode 210 and the second electrode 220 can also be coplanarly disposed on the piezoresistive material 430, such as... Figure 4b The first electrode 210 and the second electrode 220 serve as signal output electrodes for the corresponding points of the piezoresistive material 430. The measurement branch includes a piezoresistive measurement circuit, which couples the first electrode 210 and the second electrode 220 at each point via a switch array. This circuit acquires the electrical signal between the first electrode 210 and the second electrode 220 at each point when an object comes into contact with it. The piezoresistive material 430 can sense the contact pressure and position of the object, exhibiting high spatial resolution.

[0040] Furthermore, the piezoresistive material 430 forms insulating gaps between each measurement point 200 or between the aggregated areas formed by several measurement points 200. The capacitance-to-digital conversion circuit is coupled to the first electrode 210 of each point through a switch array. This is used to acquire the self-capacitance of the first electrode 210 and / or the mutual capacitance between two mutually insulated first electrodes 210 when an object approaches. The first electrode 210 serves as a proximity detection electrode. Similarly, when the three-dimensional force detection component does not detect pressure, it acts as a non-contact capacitance sensor. When an object approaches, the first electrode 210 is converted to a contact position measurement. Since the piezoresistive detection principle requires grounding, the second electrode 220 serves as the near-ground terminal of the measurement point 200. It is connected in series with the ground as a selector switch. It is grounded during piezoresistive acquisition and disconnected during capacitance acquisition to prevent the capacitance from being grounded through the piezoresistive field.

[0041] Figure 5 A possible circuit topology is shown, where S1-S4 are analog switches, R1 and R2 are piezoresistive materials, and Ir is a constant current source for piezoresistive material measurement. When used for force measurement of piezoresistive materials, S4 is open, and S1, S2, and S3 are closed. The ADC-S1-R-S3-GND loop is formed. Ir inputs current to the first electrode, and the piezoresistive change is converted to voltage by the MCU's ADC. When used for proximity and contact measurement of capacitance detection, S1, S2, and S3 are open, and S4 is closed. Due to the high input impedance of capacitance detection, the piezoresistive material is approximately short-circuited. The second electrode 30 is connected to the first electrode 20 via the piezoresistive material 10 to form a capacitor electrode. A single electrode can be used for self-capacitance detection or for mutual capacitance detection with adjacent piezoresistive electrodes. Because the piezoresistive material is approximately short-circuited... Figure 5 The CDC can be connected to the first electrode 20 and / or the second electrode 30 via a switch. In the example, it is connected to the second electrode 30 for easy drawing and routing.

[0042] When the piezoresistive material 430 is a pressure- and temperature-sensitive polymer material, similar to the temperature measurement method of piezoelectric materials, temperature measurement and pressure verification can be achieved based on the piezoresistive signals of the pressure point and adjacent non-pressure points.

[0043] 1.4 Electrode Arrangement

[0044] See Figure 2 , Figure 4a , Figure 4b In the intermediate layer material of the sensing array 300, as the first optional arrangement of electrodes, whether it is a capacitor array, a piezoelectric array, or a piezoresistive array, the first electrode 210 and the second electrode 220 of each measurement point 200 are point electrodes. The point electrodes in the same layer are arranged into an array to achieve multi-point triggering, while meeting the requirements of higher spatial resolution and lower crosstalk.

[0045] See Figure 1As a second alternative arrangement of electrodes, it is suitable for non-piezoelectric arrays such as capacitors or piezoresistors with upper and lower electrodes. The first electrode 210 and the second electrode 220 are both strip electrodes. Each first electrode 210 is arranged at a certain interval in the horizontal direction, and each second electrode 220 is arranged at a certain interval in the vertical direction, thereby forming a row and column staggered dot matrix in the vertical projection direction. The staggered positions serve as measurement points 200, which can reduce the number of leads and simplify wiring.

[0046] See Figure 6 As a third alternative electrode arrangement, suitable for capacitive or piezoelectric arrays, the first electrode 210 of each measurement point 200 is a point electrode, and these point electrodes are arranged in an array. The second electrode 220 of each measurement point 200 is integrally formed into a common electrode, with the point electrodes located above the common electrode. In the case where the three-dimensional force detection component is based on capacitive three-dimensional force detection, the second electrode 220 serves as a combined electrode for both contact detection (common electrode) and the shielding electrode of the three-dimensional force detection component. During measurement, the second electrode 220 is grounded for shielding or uses CDC input excitation to achieve equipotential shielding.

[0047] 1.5 Three-dimensional force sensing realization structure

[0048] In the sensor structure of this utility model, three-dimensional force detection is implemented based on the deformation of a flexible curved surface. The inner side of the flexible body 100 has a downwardly protruding flexible structure 110. The surface of the flexible structure 110 is curved. When the flexible body 100 is driven by external force, the curved surface of the flexible structure 110 changes, resulting in changes in light intensity, magnetic flux, resistance or capacitance, which can achieve higher three-dimensional force detection sensitivity.

[0049] See Figure 7a , Figure 7b Specifically, in one optional embodiment, as the realization of electromagnetic flexible surface deformation, the three-dimensional force detection component includes a magnetic source 710 for actively generating a magnetic field and at least three magnetic field measuring electronic elements 720. The magnetic source 710 is a permanent magnet embedded in the flexible structure 110. Each magnetic field measuring electronic element 720 is located below the flexible structure 110 and distributed around the periphery of the flexible structure 110, such as forming a Hall array using Hall elements. The magnetic field measuring electronic elements 720 are in direct or indirect contact with the curved surface of the flexible structure 110. The deformation of the flexible body 100 under external force causes the curved surface of the flexible structure 110 to change the direct or indirect contact area with the magnetic field measuring electronic elements 720. The measurement branch includes an analog-to-digital conversion circuit. The processing module is coupled to each magnetic field measuring electronic element 720 via the analog-to-digital conversion circuit to output a three-dimensional force signal based on the magnetic flux of the magnetic field measuring electronic elements 720 changed by the deformation of the flexible structure 110.

[0050] The flexible structure 110 is configured as a hemispherical pressure sensing structure with a permanent magnet embedded in the hemisphere and a Hall matrix below the hemisphere. When the upper part of the flexible hemispherical pressure sensing structure is subjected to pressure of different magnitudes and directions, the area and orientation of the part in contact with the Hall matrix below the hemisphere will change with the magnitude and direction of the force, causing the distance and orientation between the internal permanent magnet and the Hall sensor to change in the same direction, thus changing the magnetic flux of the Hall sensor matrix. By detecting the output of the Hall sensor, the magnitude and direction of the pressure can be decoupled. Due to the curved surface change and rolling contact, the sensitivity of force detection is higher, and the Hall sensor has a fast response speed and a high signal-to-noise ratio.

[0051] The aforementioned Hall-effect 3D detection component can be combined with a capacitor array, piezoelectric array, or piezoresistive array to form a composite sensor. The Hall-effect 3D detection component cannot achieve proximity detection and is insensitive to electric fields. However, by setting an array on it, the electrodes in the array are reused for proximity detection, and the electric field of the capacitor itself does not affect the 3D force measurement accuracy of the Hall-effect 3D detection component. The combination of force-sensitive materials, capacitors, and flexible hemispherical Hall sensors can compensate for the shortcomings of each individual component.

[0052] The flexible upper surface of the Hall effect 3D detection component is not limited to a plane; it can also include a convex curved surface, which is more in line with engineering practice. Figure 7c .

[0053] See Figure 8a In another optional embodiment, as the realization of photoelectric flexible surface deformation, the flexible body 100 includes a light-sealed region, with the flexible body 100 serving as a partial boundary of the light-sealed region. The three-dimensional force detection component includes a flexible structure 110 protruding downward from the inside of the flexible body 100, a light-emitting channel located within the light-sealed region below the flexible structure 110, and at least three photosensitive electronic elements 820 located within the light-sealed region for receiving light reflected from the flexible structure 110. The light-emitting channel is either a surface light source 810 as the light emitter or a transparent material such as glass, with the light source positioned underneath. The illustration uses a surface light source 810 as an example. The photosensitive electronic elements 820 are photodetectors. The flexible structure 110 is made of an opaque material, and the photosensitive electronic elements 820 are distributed around the periphery of the flexible structure 110. The light-emitting channel is used to emit light directed towards the flexible structure 110 through the light source. The flexible structure 110 deforms under external pressure, changing the area of ​​obstruction of the light passing through the light-emitting channel. The measurement branch includes an analog-to-digital converter circuit. The processing module is coupled to each photosensitive electronic element 820 via the analog-to-digital converter circuit to output a three-dimensional force signal based on the change in reflected light caused by the deformation of the flexible structure 110.

[0054] The 820 photosensitive electronic component employs a low-cost, small-volume photodetector. A hemispherical flexible reflector is positioned above the light-emitting / transmitting element, and at least three evenly distributed photodetectors are arranged around its perimeter. Light emitted / transmitted by the light-emitting / transmitting element is reflected by the reflective surface of the hemispherical flexible reflector to the photodetectors. When the hemispherical light-emitting element is subjected to forces of different magnitudes and directions, the contact area and direction between the hemispherical flexible reflector and the light-emitting / transmitting element change accordingly, altering the light-emitting area of ​​the light-emitting / transmitting element and thus changing the intensity of the light reflected to the photodetectors. The magnitude and direction of the pressure are determined by detecting the voltage / current of the photodetectors. Because the hemispherical flexible reflector is pressed down under external force, changing its blocking area on the channel, the light passing through the channel is altered. This results in a significant change in the intensity of the light projected onto the hemispherical flexible reflector within the light-sealed area. The output signal fluctuation range of the photoelectric receiver, based on the altered reflected light due to the deformation of the flexible structure 110, is greatly improved, achieving high detection sensitivity for the sensor. Simultaneously, the photoelectric sensor exhibits fast response speed, strong anti-interference capability, and high accuracy. Its drawback is that it cannot achieve high spatial resolution arrangement; combining it with the sensing array 300 can compensate for this deficiency. See [link / reference]. Figure 8b , Figure 8c The upper surface of the flexible body of the photoelectric three-dimensional detection component is not limited to a plane, but may also include a convex curved surface.

[0055] See Figure 9a , Figure 9bIn another alternative embodiment, as a means of realizing the deformation of the capacitive flexible surface, the three-dimensional force detection component includes an upper electrode disposed on the flexible structure 110, and at least three lower electrodes 920 located below the upper electrode. For structural simplification, the flexible structure 110 can be made of a conductive material as the upper electrode, and the lower electrodes 920 can be disposed on a circuit board 930, which is mounted on a support 940. The flexible structure 110 is supported by a rigid support 950. A sensing array 300 is also disposed on the flexible body 100 on which the flexible structure 110 is located, and the sensing array is protected by an insulating silicone 960. The flexible structure 110 adopts a convex hemisphere, making the upper electrode a curved elastic electrode. An insulating layer is set between the upper electrode and the lower electrode 920. Each lower electrode 920 is distributed around the periphery of the flexible structure 110. The downward projection of the upper electrode covers at least a portion of the area of ​​each lower electrode 920. The deformation of the flexible multifunctional layer under external force causes the upper electrode to change the indirect contact area with the insulating layer. The measurement branch includes a capacitance-to-digital conversion circuit, which is coupled to the upper electrode and each lower electrode 920 to obtain the capacitance between the upper electrode and each lower electrode 920. The processing module is coupled to the capacitance-to-digital conversion circuit to output a three-dimensional force signal based on the change in capacitance between the upper electrode and each lower electrode 920 caused by the deformation of the flexible structure 110. The deformation of the flexible curved surface based on the change in contact area also has the characteristic of high force detection sensitivity.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit the scope of protection of this utility model. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the essence and scope of the technical solutions of this utility model.

Claims

1. A three-dimensional force sensor with high spatial resolution, characterized in that: It includes a measurement branch, a processing module, a switch array, and at least one sensing unit; Each sensing unit has a flexible body for contacting external objects. The flexible body contains a three-dimensional force detection component that generates changes in light intensity, magnetic flux, resistance, or capacitance through force deformation. The three-dimensional force detection component serves as the smallest mechanical sensing unit in the sensor and is used to independently detect three-dimensional forces. Each sensing unit has at least two measurement points distributed on its flexible body. The measurement points are arranged at different positions on the corresponding flexible body to form a sensing array of the sensing unit. Each measurement point in the sensing array is used to detect the spatial position of the force application point of the corresponding sensing unit's flexible body. The measurement branch is coupled with a three-dimensional force detection component to obtain a first type of detection data, and each measurement point is coupled through a switch array to obtain a second type of detection data; The processing module is coupled to the measurement branch and is used to output a three-dimensional force signal based on the first type of detection data and a spatially resolved signal based on the second type of detection data.

2. The three-dimensional force sensor according to claim 1, characterized in that: Each measurement point includes a first electrode and a second electrode stacked one on top of the other, and the projection of the first electrode relative to the second electrode covers at least a portion of the area of ​​the second electrode. The measurement branch includes a capacitance-to-digital converter circuit. The capacitance-to-digital converter circuit couples the first electrode and the second electrode at each point through a switch array to obtain the mutual capacitance between the first electrode and the second electrode at each point. The first electrode and the second electrode serve as capacitance sensing electrodes.

3. The three-dimensional force sensor according to claim 1, characterized in that: Each measurement point is equipped with a piezoelectric material, a first electrode and a second electrode respectively set on the upper and lower surfaces of the piezoelectric material. The piezoelectric material between each measurement point is either integrated or separate. The first electrode and the second electrode serve as signal output electrodes of the piezoelectric material at the corresponding point. The measurement branch includes a piezoelectric measurement circuit. The piezoelectric measurement circuit couples the first electrode and the second electrode at each point through a switch array to acquire the electrical signal between the first electrode and the second electrode at each point. The piezoelectric measurement circuit includes a charge amplifier to amplify the electrical signal.

4. The three-dimensional force sensor according to claim 3, characterized in that: The projection of the first electrode relative to the second electrode at least covers a portion of the area of ​​the second electrode; The measurement branch includes a capacitance-to-digital conversion circuit. The capacitance-to-digital conversion circuit couples the first electrode and the second electrode at each point through a switch array to obtain the mutual capacitance between the first electrode and the second electrode at each point. The first electrode and the second electrode serve as multiplexed electrodes for the capacitance sensing electrode and the signal output electrode of the piezoelectric material.

5. The three-dimensional force sensor according to any one of claims 1-4, characterized in that: Each measurement point includes at least a first electrode, and the measurement branch includes a capacitance-to-digital converter circuit. The capacitance-to-digital converter circuit is coupled to the first electrode of each point through a switch array to obtain the self-capacitance of the first electrode and / or the mutual capacitance between the first electrodes of two points. The first electrode serves as at least a proximity detection electrode.

6. The three-dimensional force sensor according to claim 1, characterized in that: Each measurement point is equipped with a piezoresistive material, and each measurement point's piezoresistive material is equipped with a first electrode and a second electrode. The first electrode and the second electrode are respectively located on the upper and lower surfaces of the piezoresistive material, and the first electrode and the second electrode serve as the signal output electrodes of the piezoresistive material at the corresponding point. The measurement branch includes a piezoresistive measurement circuit, which couples the first electrode and the second electrode at each point through a switch array to acquire the electrical signal between the first electrode and the second electrode at each point when the object is in contact.

7. The three-dimensional force sensor according to claim 1, characterized in that: Each measurement point is equipped with a piezoresistive material, and the piezoresistive material at each measurement point is equipped with a first electrode and a second electrode. The first electrode and the second electrode are coplanarly disposed on the piezoresistive material, and the first electrode and the second electrode serve as the signal output electrodes of the piezoresistive material at the corresponding point. The measurement branch includes a piezoresistive measurement circuit, which couples the first electrode and the second electrode at each point through a switch array to acquire the electrical signal between the first electrode and the second electrode at each point when the object is in contact.

8. The three-dimensional force sensor according to claim 6 or 7, characterized in that: Piezoresistive materials are used to form insulating gaps between individual measurement points or between aggregated areas formed by several measurement points; The second electrode serves as the near-ground end of the measurement point, and a selector switch is connected in series between the second electrode and the ground. The measurement branch includes a capacitance-to-digital conversion circuit, which is coupled to the first electrode at each point through a switch array. This circuit is used to acquire the self-capacitance of the first electrode and / or the mutual capacitance between two mutually insulated first electrodes when an object approaches. The first electrode serves as the proximity detection electrode.

9. The three-dimensional force sensor according to claim 2, 3 or 4, characterized in that: The first electrode at each measurement point is a point electrode, and the point electrodes are arranged in an array. The second electrode at each measurement point is integrated to form a common electrode, and the point electrodes are located above the common electrode.

10. The three-dimensional force sensor according to claim 9, characterized in that: The three-dimensional force detection component is based on capacitive three-dimensional force detection. The second electrode serves as a reused electrode for both the common electrode for contact detection and the shielding electrode for the three-dimensional force detection component.

11. The three-dimensional force sensor according to claim 2, 3, 4, 6 or 7, characterized in that: The first and second electrodes at each measurement point are point electrodes, and the point electrodes in the same layer are arranged in an array.

12. The three-dimensional force sensor according to claim 2 or 6, characterized in that: Both the first electrode and the second electrode are strip electrodes. The first electrodes are arranged at a certain interval along the horizontal direction, and the second electrodes are arranged at a certain interval along the vertical direction, thus forming a row-and-column staggered dot matrix in the vertical projection direction. The staggered positions are used as the measurement points.

13. The three-dimensional force sensor according to claim 1, 2, 3, 4, 6 or 7, characterized in that: The flexible body has a downwardly protruding flexible structure on its inner side, and the surface of the flexible structure is curved. The changes in light intensity, magnetic flux, resistance, or capacitance are caused by the deformation of the flexible structure of the flexible body under external force.

14. The three-dimensional force sensor according to claim 13, characterized in that: The three-dimensional force detection component includes a magnetic source for actively generating a magnetic field and at least three magnetic field measuring electronic components. The magnetic source is embedded in a flexible structure, and each magnetic field measuring electronic component is located below the flexible structure and distributed around the periphery of the flexible structure. The magnetic field measuring electronic components are in direct or indirect contact with the curved surface of the flexible structure. When the flexible body is deformed by external force, the curved surface of the flexible structure changes and the direct or indirect contact area with the magnetic field measuring electronic components changes. The measurement branch includes an analog-to-digital converter circuit. The processing module is coupled to each magnetic field measurement electronic component via the analog-to-digital converter circuit, and is used to output a three-dimensional force signal based on the magnetic flux of the magnetic field measurement electronic component changed by the deformation of the flexible structure.

15. The three-dimensional force sensor according to claim 13, characterized in that: The flexible body includes a light-sealed region, and the flexible body serves as a partial boundary of the light-sealed region. The three-dimensional force detection component includes the flexible structure protruding downward from the inside of the flexible body, a light-emitting channel located in the light-sealed region below the flexible structure, and at least three photosensitive electronic elements located in the light-sealed region for receiving light reflected from the flexible structure. The flexible structure is made of opaque material, and each photosensitive electronic element is distributed around the periphery of the flexible structure. The light emission channel is used to emit light that is directed toward the flexible structure through a light source. The flexible structure deforms under external pressure, changing the area of ​​blocking the light passing through the light emission channel. The measurement branch includes an analog-to-digital conversion circuit, and the processing module is coupled to each photosensitive electronic element via the analog-to-digital conversion circuit to output a three-dimensional force signal based on the change in reflected light caused by the deformation of the flexible structure.

16. The three-dimensional force sensor according to claim 13, characterized in that: The three-dimensional force detection component includes an upper electrode disposed on the flexible structure, and at least three lower electrodes located below the upper electrode. The upper electrode is a curved elastic electrode. An insulating layer is provided between the upper electrode and the lower electrode. Each lower electrode is distributed around the flexible structure. The downward projection of the upper electrode covers at least part of the area of ​​each lower electrode. The flexible multifunctional layer is deformed by external force, which causes the upper electrode to change the indirect contact area with the insulating layer. The measurement branch includes a capacitance-to-digital conversion circuit, which is coupled to the upper electrode and each lower electrode respectively, and is used to obtain the capacitance between the upper electrode and each lower electrode. The processing module is coupled with a capacitor-to-digital converter circuit, which is used to output a three-dimensional force signal based on the capacitance between the upper electrode and each lower electrode as the flexible structure deforms.

17. An electronic skin, characterized in that, Including a three-dimensional force sensor with high spatial resolution as described in any one of claims 1-16.

18. A robot, characterized in that, Including the electronic skin as described in claim 17.

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