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CN-122016097-A - Flexible three-dimensional capacitive force sensor and preparation and resolving method thereof

CN122016097ACN 122016097 ACN122016097 ACN 122016097ACN-122016097-A

Abstract

The invention discloses a flexible three-dimensional capacitive force sensor and a preparation and resolving method thereof, comprising a flexible base, a force bearing column integrally formed with the flexible base, five capacitive sensing units arranged around the force bearing column and a flexible boss top cover arranged above the flexible base; the top capacitance sensing units are used for detecting normal force, the four side wall capacitance sensing units are used for detecting shearing force in two orthogonal directions in pairs, and preliminary decoupling of the normal force and the shearing force on a structural layer is realized through spatial distribution of the top and side wall sensing units and design of a load transmission path between the boss top cover and the bearing cylinder. The invention also provides a capacitance signal acquisition module in a matched manner, and realizes real-time calculation of normal force and shearing force in two orthogonal directions by carrying out feature extraction and neural network mapping on five paths of capacitance signals, thereby compensating the nonlinear and miniaturized structural residual coupling of the flexible material.

Inventors

  • SONG AIGUO
  • YANG YUNBO

Assignees

  • 东南大学

Dates

Publication Date
20260512
Application Date
20260331

Claims (10)

  1. 1. The flexible three-dimensional capacitive force sensor is characterized by comprising a flexible base, a force bearing column body integrally formed with the flexible base, five capacitive sensing units and a flexible boss top cover arranged above the flexible base; The five capacitance sensing units are respectively positioned on the top of the bearing column body and four side walls of the bearing column body, wherein the top capacitance sensing unit is used for representing normal force response, one pair of side wall capacitance sensing units at opposite positions is used for representing X-direction shear force response, and the other pair of side wall capacitance sensing units at opposite positions is used for representing Y-direction shear force response; the flexible boss top cover is internally provided with a boss structure for bearing external load, and is in an internal cavity type structure when being sealed with the bearing column body and four side walls of the bearing column body; When external shear load acts on the flexible boss top cover, relative lateral displacement is generated between the flexible boss top cover and the force-bearing column body, so that differential response is generated by the side wall capacitance sensing units corresponding to the side wall direction, and the detection of normal force and X, Y shearing force in the orthogonal direction is realized.
  2. 2. The flexible three-dimensional capacitive force sensor of claim 1, wherein the capacitive sensing element comprises a flexible electrode, a flexible dielectric layer and a flexible electrode from top to bottom, wherein the flexible electrode is prepared by a flexible printed circuit board, and the flexible dielectric layer is formed by a polydimethylsiloxane flexible dielectric film.
  3. 3. The flexible three-dimensional capacitive force sensor of claim 1, wherein the five capacitive sensing units are connected to five surfaces of the force-bearing cylinder, and wherein the lower surface of the flexible boss top cover is connected to the upper surface of the base and completely covers the cross section of the top end of the force-bearing cylinder.
  4. 4. The flexible three-dimensional capacitive force sensor of claim 1, wherein the flexible base has a planar dimension of 10mm ×10mm, the force-bearing column has a square shape with a side length of 6 mm, the boss structure in the flexible boss top cover has a planar dimension of 6 mm ×6 mm, and the outer contour dimension of the lower portion of the flexible boss top cover is 10mm ×10 mm.
  5. 5. A method of manufacturing a flexible three-dimensional capacitive force sensor according to any of claims 1 to 4, comprising the steps of: S1, preparing an integrally formed flexible base-bearing column structure and a flexible boss top cover, wherein the flexible base-bearing column structure and the flexible boss top cover are obtained by pouring a polydimethylsiloxane material into a mold, curing and demolding; S2, preparing five capacitance sensing units, wherein each capacitance sensing unit is composed of an upper flexible electrode, a lower flexible electrode and a flexible dielectric layer arranged between the upper flexible electrode and the lower flexible electrode; S3, fixing one capacitance sensing unit on the top of the bearing cylinder, and fixing the other four capacitance sensing units on the four side walls of the bearing cylinder respectively; S4, aligning and packaging the flexible boss top cover and the flexible base, so that the cavity structure of the flexible boss top cover covers the bearing column body and the side wall capacitance sensing unit, and a flexible three-dimensional capacitance type force sensor is obtained.
  6. 6. A three-dimensional force detection system comprising a flexible three-dimensional capacitive force sensor according to any one of claims 1 to 4, a capacitive signal acquisition module and a processing unit; the capacitance signal acquisition module is connected with the five capacitance sensing units, and is used for independently reading capacitance signals of the five capacitance sensing units and transmitting measurement results to the processing unit; The processing unit is used for calculating and obtaining normal force and X, Y shear force components in two orthogonal directions according to the measurement results of the five capacitance sensing units.
  7. 7. The three-dimensional force detection system of claim 6, wherein the five capacitive sensing units are respectively composed of two electrodes and lead out ten electrode signal wires, the ten electrode signal wires are respectively used as two ends of the five capacitive sensing units to be input, and are connected to five groups of measuring ends corresponding to the capacitive signal acquisition module to complete capacitive signal reading.
  8. 8. A three-dimensional force resolving method of a flexible three-dimensional capacitive force sensor using the flexible three-dimensional capacitive force sensor according to claim 1, comprising the steps of: S1, collecting real-time measurement values of five capacitance sensing units, and performing zero calibration to obtain corresponding capacitance variation delta C 0 、ΔC 1 、ΔC 2 、ΔC 3 and delta C 4 , wherein the top normal load of delta C 0 Corresponding to , the X-direction shearing information corresponding to delta C 1 and delta C 3 , and the Y-direction shearing information corresponding to delta C 2 and delta C 4 ; S2, carrying out characteristic construction on the capacitance variation according to the spatial distribution relation of the top capacitance sensing unit and the four side wall capacitance sensing units to obtain characteristic vectors used for representing normal response, shearing differential response, side wall coupling compensation and the proportion relation between the center and the periphery; And S3, inputting the feature vector into a pre-trained neural network model to obtain a normal force and a solution result of two shearing force components in the orthogonal direction.
  9. 9. The method for resolving three-dimensional force of flexible three-dimensional capacitive force sensor according to claim 8, wherein the feature vectors used for characterizing normal response, shear differential response, sidewall coupling compensation and center-to-perimeter response proportional relation in step S2 are specifically: ; ; ; ; ; ; Wherein, x 1 is used for representing normal response, x 2 and x 3 are used for representing shear differential response, x 4 and x 5 are used for representing sidewall coupling compensation information, and x 6 is used for reflecting the center and peripheral response proportional relationship.
  10. 10. The method of three-dimensional force calculation for a flexible three-dimensional capacitive force sensor according to claim 9, wherein the neural network model in the step S3 is a multi-layer feedforward neural network structure, wherein the network hiding layers are three layers, the number of neurons of the full-connection layers is 64, 128 and 64 respectively, each hiding layer adopts a ReLU nonlinear activation function, and the output layer adopts a linear output mode for completing continuous value regression prediction of three-dimensional force components.

Description

Flexible three-dimensional capacitive force sensor and preparation and resolving method thereof Technical Field The invention belongs to the technical field of flexible electronics and multidimensional force sensing, and mainly relates to a flexible three-dimensional capacitive force sensor and a preparation and resolving method thereof, in particular to a miniaturized flexible sensing structure capable of detecting normal force and shearing force in two orthogonal directions simultaneously, and a signal acquisition and three-dimensional force resolving scheme matched with the structure. Background With the development of wearable equipment, flexible electronics, rehabilitation therapy, plantar monitoring, robot tactile perception and other technologies, the application requirements of the multidimensional force sensor in human motion monitoring, human-computer interaction and intelligent perception are continuously increased. In applications such as plantar stress monitoring, diabetic foot risk assessment, gait analysis, and robot end tactile feedback, the sensor is required to sense not only normal pressure, but also shear forces in two orthogonal directions synchronously so as to more comprehensively reflect the mechanical state of the contact interface. Existing multidimensional force sensors typically employ multiple single axis sensing element combinations, rigid structure layered stacks, or complex microstructure designs to achieve multi-directional force detection. The scheme often has the problems of large device volume, complex structure, unclear stress path, insufficient flexibility, strong coupling among channels, difficulty in integration in a small area and the like, and is difficult to adapt to space-limited scenes such as insoles, attached flexible devices or curved surface tactile surfaces of robots. In recent years, flexible capacitive sensors have received attention because of their simple structure, low power consumption, suitability for flexible integration, and the like. However, the existing flexible capacitive sensors mostly focus on normal pressure detection, and have limited synchronous detection capability for shearing force, especially biaxial shearing force. On the other hand, the flexible material has the characteristics of nonlinear deformation, local stress concentration, hysteresis and the like in the stress process, so that residual coupling is easy to generate between loads in different directions, and the multi-dimensional force decoupling precision and the measurement stability are difficult to be considered under the miniaturized condition by adopting the traditional linear calibration method. Therefore, it is necessary to provide a flexible three-dimensional force sensor which has a compact structure, good flexibility, is suitable for miniaturization and integration, can realize synchronous detection of normal force and shearing force in two orthogonal directions, and can perform high-precision decoupling by combining a data driving method, and an implementation scheme thereof. Disclosure of Invention The invention provides a flexible three-dimensional capacitive force sensor and a preparation and resolving method thereof, which aim at the problems that the prior multi-dimensional force sensor has large structure volume, insufficient flexibility, complex stress path, obvious channel coupling and difficulty in realizing synchronous detection of high-precision normal force and shearing force under the miniaturized condition, and comprises a flexible base, a bearing column integrally formed with the flexible base, five capacitance sensing units arranged around the bearing column and a flexible boss top cover arranged above the flexible base; the top capacitance sensing units are used for detecting normal force, the four side wall capacitance sensing units are used for detecting shearing force in two orthogonal directions in pairs, and preliminary decoupling of the normal force and the shearing force on a structural layer is realized through spatial distribution of the top and side wall sensing units and design of a load transmission path between the boss top cover and the bearing cylinder. The invention also provides a capacitance signal acquisition module in a matched manner, and realizes real-time calculation of normal force and shearing force in two orthogonal directions by carrying out feature extraction and neural network mapping on five paths of capacitance signals, thereby compensating the nonlinear and miniaturized structural residual coupling of the flexible material. The invention has the characteristics of compact structure, good flexibility, convenient integration, strong multidimensional force detection capability and the like, and is suitable for the scenes of plantar monitoring, wearable equipment, robot touch perception and the like. In order to achieve the aim, the technical scheme adopted by the invention is that the flexible three-dimensional capacitive