Continuous area flexible touch skin with irregular boundaries

Abstract

The invention relates to a continuous region flexible haptic skin with irregular boundaries. The sensing area of the flexible touch skin is continuous, signal detection positions are distributed on the boundary of the sensing area, detection of global touch information in any irregular-shaped sensing area can be achieved, and no detection blind area exists in the sensing area. The flexible touch skin is made of a high-elasticity pressure-sensitive flexible sensing material, an elastic structure serves as a substrate, a rigid structure serves as a support, the sensing skin with a touch sensing effect is formed, and the flexible touch sensing requirements of various rigid mechanical structures are met. According to the invention, global and non-blind area information detection of an irregular boundary continuous area is realized, detection electrodes can be arranged at the boundary of a sensing area in any shape, a tactile sensing function from a small amount of boundary electrode signals to global area information is realized, the defect that the universality of a simple-shape sensor is limited is overcome, and the detection accuracy is improved. And the problem of inter-unit detection blind areas caused by the utilization of isolated sensing units is avoided.

Description

Technical Field

[0001] The invention belongs to the field of sensing technology and is a flexible tactile skin with continuous areas and irregular boundaries. Background Art

[0002] Large-area flexible sensing skins are key to achieving full-body perception in service robots and ensuring safe human-robot interactions. Large-area sensing methods, which collect signals only from the boundaries of the sensing area, offer promising detection methods for continuous area sensing with minimal wiring complexity. However, most current continuous area sensing methods are limited to simple shapes such as squares and circles, severely limiting the widespread application of flexible sensors in complex human-robot interfaces.

[0003] In response to the above problems, some solutions have been proposed. For example, the authorized invention patent CN201610450943.3 addresses the need to measure the pressure distribution in irregular areas of the sole of the foot. By setting multiple isolated sensitive units at different positions in the sole area, the pressure distribution in the sole area is obtained through a mathematical model. This invention solves the problem of detecting the stress distribution of irregular shapes on the sole of the foot, but the use of isolated sensitive units and the physical gaps between the sensitive units lead to the problem of blind spots in the pressure distribution. Array sensing methods are widely used for large-area sensing, but the row and column signals of the array sensing method have crosstalk problems. For example, the authorized invention patent CN202411465309.8 addresses the signal crosstalk problem in the pressure sensing array and proposes an anti-crosstalk detection circuit that can improve the crosstalk phenomenon of the capacitive pressure sensing array. The array sensing method is mostly used for square sensing areas, which is difficult to cover irregular surfaces, seriously limiting its promotion and application in complex-shaped human-computer interaction interfaces. Against the background of the above technology, the present invention adopts a non-isolated, continuous regional sensing method, which uses field-distributed electrical signals to make up for the shortcomings of isolated sensing units and array sensing methods, and realizes the detection of continuous information in irregular sensing areas. Summary of the Invention

[0004] The purpose of the present invention is to address the shortcomings of the existing technology and propose a flexible tactile skin with continuous areas of irregular boundaries. It predicts the tactile information of the global area based on a small number of boundary electrode signals, realizes blind-spot information detection of continuous areas with irregular boundaries, improves the regional information sensing performance of the flexible tactile skin, and improves its adaptability in complex human-computer interaction scenarios.

[0005] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0006] A continuous area flexible tactile skin with irregular boundaries, comprising a flexible sensing area, boundary electrodes, and an elastic substrate, characterized in that:

[0007] The flexible sensing area is composed of a highly elastic pressure-sensitive conductive composite sensing material and has a continuous feature. The sensing area has no detection electrodes and no detection blind areas.

[0008] The conductive composite sensing material is composed of a piezoresistive or piezoresistive conductive particle-elastic matrix composite material. When an external load is applied, the resistance of the composite material in the deformed area increases, while the resistance in the undeformed area remains unchanged. The composite material includes:

[0009] Conductive particles are micro-nano-sized flake, strip, or spherical particles. They can form direct conductive pathways between particles, or indirect tunneling current pathways. Together, these conductive pathways and tunneling pathways enable continuous sensing without blind spots.

[0010] The elastic matrix, composed of a low mechanical modulus material, provides a uniformly dispersed medium for the conductive particles and limits the displacement of the conductive particles under touch pressure, thereby adjusting the number of electrical conduction paths in the sensing area under touch pressure and changing the local electrical parameters at the touch pressure position.

[0011] The boundary electrodes are distributed at the edges of the sensing area, forming conductive point-like connections with the sensing area. The number and position of the boundary electrodes are not limited, and the boundaries of any irregular sensing area of ​​any shape can be covered in a uniform or non-uniform layout. Any pair of boundary electrodes can serve as a pair of driving electrodes, connected to the positive and negative electrodes of a constant driving current, or as a pair of detection electrodes, collecting the potential difference between the electrodes. By establishing an irregular shape sensing model, a continuous touch pressure information distribution within the sensing area is obtained.

[0012] The establishment of the irregular shape sensing model comprises the following steps:

[0013] Step 1: Determine a mathematical function expression of the boundary contour of the irregular sensing area, which may be a linear, hyperbolic, or trigonometric function, to form a closed function of the boundary contour of the sensing area;

[0014] Step 2: Divide the sensing area into a finite element grid. Determine the type of finite element unit based on the plane or curved surface characteristics of the actual sensing area. The size of the unit cell affects the accuracy of the large-area sensing model. The smaller the size, the higher the model accuracy.

[0015] Step 3: Determine the number and position coordinates of the boundary point electrodes. There is no limit to the number of boundary electrodes, and the position of the boundary electrodes is defined by the vertex coordinates of the cell. The process of collecting boundary signals is to input a driving current to a pair of boundary electrodes, detect the potential difference between all other electrode pairs, change the position of the driving electrode pair in a clockwise or counterclockwise order, and detect the potential difference between all other electrode pairs again. The signal detection process meets the requirement of full cyclic coverage.

[0016] The elastic substrate has flexible characteristics, is non-pressure-sensitive, and has no conductive properties, and plays the role of insulating the flexible sensing area and the rigid mechanical structure, thereby improving the detection quality of the boundary signal.

[0017] Preferably, the elastic substrate may be a fabric substrate, an open-type or closed-type foam substrate, or a superelastic silicone material.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The sensing area of ​​the present invention has an irregular shape, and the position distribution of the boundary electrodes can be arbitrarily adjusted. Although the physical shape of the sensor is diverse, the method for establishing a sensing model for irregular shapes is universal. It is only necessary to update the boundary contour function according to the actual shape of the sensing area, determine the position coordinates of the boundary electrodes, and establish a finite element network in a universal manner to obtain the loading information within the sensing area under different drive-acquisition modes. This has a wide adaptability.

[0020] 2. The present invention adopts conductive particle elastomer composite sensing material, which can obtain continuous and arbitrarily shaped tactile skin on various interfaces such as flat and non-flat surfaces through surface processing methods such as spraying, rolling, and printing, thereby improving the applicable scenarios of flexible tactile skin.

[0021] 3. The elastic substrate and rigid support structure of the present invention are necessary sensing structures for irregular flexible tactile skin to sense touch and pressure loading, providing a basis for existing rigid mechanical structures to achieve tactile perception, thereby reducing the cost of customizing flexible tactile skin for mature equipment such as rigid robots. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The flexible touch skin with a large continuous area and irregular boundaries according to the embodiment of the present invention

[0023] Figure 2 The sensing model and signal detection method of the irregular-shaped flexible touch skin according to the embodiment of the present invention are

[0024] Figure 3 Schematic diagram of tactile information reconstruction with irregular boundary shape according to an embodiment of the present invention

[0025] Numbers in the figure: 1 flexible sensing area; 2 boundary electrode; 3 elastic substrate; 4 rigid support; 5 elastic matrix; 6 conductive particles DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0027] Figure 1The present invention relates to a flexible tactile skin with a large continuous area and irregular boundaries. The applicable scenario of the flexible tactile skin is a human-machine interaction interface with an actual complex shape. This embodiment takes a human upper body model as an example to realize a tactile skin with a vest-shaped sensing area. The flexible sensing area (1) is composed of a pressure-sensitive conductive composite sensing material, including an elastic substrate (5) and conductive particles (6), which has both mechanical flexibility and pressure-sensitive properties, and realizes touch pressure signal perception in a continuous sensing area without blind spots. Several boundary electrodes (2) are arranged at the edge of the irregular sensing area, and each electrode forms a point-like electrical connection with the sensing area for inputting a driving current or collecting a boundary voltage signal. Below the sensing area is an elastic substrate (3), which provides a substrate for the pressure-sensitive composite sensing material, on the one hand improving the pressure sensitivity of the sensing film, and on the other hand improving the wearability of the tactile skin. The bottom layer is a rigid bracket (4), which provides mechanical support for the tactile skin. The flexible tactile structure composed of the sensing area, the elastic substrate, and the rigid bracket can cover a human-machine tactile interaction interface of any shape.

[0028] Figure 2 This is a sensing model and signal detection method for irregular-shaped flexible touch skin according to an embodiment of the present invention. According to the shape of the vest sensing area, the polygon ABCDEFGHIJK is used to approximate the boundary shape ( Figure 2 a), and divide the sensing area into a grid of triangular finite elements ( Figure 2 b) The number of grids affects the spatial resolution of regional sensing. The quality and convergence of the grid division are related to the boundary function of the sensing area. In order to reduce or eliminate the irregular grids (for example, triangular units with large side length ratios), the form of the boundary function can be adjusted to use linear functions, hyperbolic functions, or trigonometric functions. The number and location of boundary electrodes at the boundary of the irregular sensing area are selected, such as Figure 2 As shown in c, the selection method can be uniform distribution or non-uniform distribution. The position of the boundary electrode is defined according to the vertex coordinates of the triangular unit. The boundary signal of the irregular sensing area is processed in the adjacent drive-adjacent acquisition mode, as shown in Figure 2 As shown. A constant current source is used to inject a constant current into a pair of adjacent electrodes, and the potential difference of all other adjacent electrodes is measured at the same time; the position of the driving electrode pair is changed in a clockwise or counterclockwise order, and the potential difference of all other adjacent electrodes is measured; according to this method, two groups of boundary signals are collected before and after the sensing area is loaded, and the distribution of loading information in the sensing area is obtained. When 16 boundary electrodes are selected, the voltage data between 16 pairs of adjacent electrodes can be collected in each driving state; for all 16 driving states, a total of 256 boundary voltage data are collected. A group of boundary signals collected at the boundary electrodes of the vest-shaped sensing area is shown as follows. Figure 2 As shown in e.

[0029] Figure 3 This is a schematic diagram of the reconstruction of tactile information with an irregular boundary shape according to an embodiment of the present invention. Based on the voltage signal collected from the boundary electrode of the irregular sensing area, the reconstructed images of different loading positions are obtained by open source electrical impedance imaging. By changing the position of the touch pressure loading, the vest-shaped tactile skin is pressed, including six positions from ① to ⑥, and the range of action is circular. The reconstructed image shows the area spreading outward from the pressing position as the center. The high and low reconstruction values ​​reflect the magnitude of the loading intensity, the shape of the reconstructed area reflects the distribution of the touch pressure loading, and the position of the reconstructed area reflects the position information of the touch pressure loading. Therefore, according to the reconstructed image, information such as the intensity, contact range, and contact position of the touch pressure loading can be obtained respectively. The vest-shaped tactile skin effectively realizes the loading state detection of irregular continuous sensing areas. By comparing the loading at different positions and the same conditions (same intensity, contact range), it is found that the reconstructed image of the irregular shaped sensing area shows position correlation. For example, the reconstructed image of the pressing position ⑤ is circular, spreading outward in a symmetrical form, and the color changes from dark to light evenly, which meets the loading conditions of the circular area. However, the reconstructed image at pressed position ① is elliptical, and the reconstructed values ​​spread out unevenly, resulting in shape distortion in the detection of circular loading. This indicates that sensing skin in irregular continuous areas requires quantitative analysis of sensing performance to accurately interpret contact pressure loading information.

[0030] It should be emphasized that the embodiments of the present invention are illustrative. Those skilled in the art will readily appreciate that the disclosed continuous-area flexible sensing skin with irregular boundaries can be applied to various other flexible sensors, or other sensors that detect external stimuli such as temperature, humidity, and pH. Therefore, the above embodiments are not intended to be limiting.

Claims

1. A continuous-area flexible tactile skin with irregular boundaries, comprising a flexible sensing area, boundary electrodes, and an elastic substrate, characterized in that: The flexible sensing area is composed of an elastic pressure-sensitive conductive composite sensing material, and the conductive composite sensing material comprises: Conductive particles are micro-nano-sized flake, strip, or spherical particles. The particles form direct contact conductive paths or indirect contact tunneling current paths. The conductive paths and tunneling paths together achieve a continuous sensing function without blind spots in the sensing area. The elastic matrix provides a uniformly dispersed medium for the conductive particles and limits the displacement of the conductive particles under the action of touch pressure, thereby adjusting the number of electrical conduction paths in the sensing area under the action of touch pressure and changing the local electrical parameters at the touch pressure position. The boundary electrodes are distributed at the edge of the sensing area, forming a conductive point connection with the sensing area, and can cover the boundaries of irregular sensing areas of any shape with a uniform or non-uniform layout; any pair of boundary electrodes serves as a pair of driving electrodes, respectively connected to the positive and negative poles of a constant driving current, or a pair of boundary electrodes serves as a pair of detection electrodes to collect the potential difference between the electrodes. By establishing an irregular shape sensing model, a continuous touch pressure information distribution within the sensing area is obtained.

2. The continuous area flexible tactile skin with irregular boundaries according to claim 1, characterized in that: The establishment of the irregular shape sensing model comprises the following steps: Step 1: Determine a mathematical function expression of the boundary contour of the irregular sensing area, which is a linear, hyperbolic or / and trigonometric function, to form a closed function of the boundary contour of the sensing area; Step 2: Divide the sensing area into finite element grids. Determine the type of finite element unit based on the plane or curved surface characteristics of the actual sensing area. The size of the unit cell affects the accuracy of the large-area sensing model. The smaller the size, the higher the model accuracy. Step 3: Determine the number and position coordinates of the boundary point electrodes; the position of the boundary electrodes is defined by the vertex coordinates of the cell; the boundary signal acquisition process is to input a driving current to a pair of boundary electrodes, detect the potential difference between all other electrode pairs, change the position of the driving electrode pair in a clockwise or counterclockwise order, and detect the potential difference between all other electrode pairs again.

3. The continuous area flexible tactile skin with irregular boundaries according to claim 1, characterized in that: The elastic substrate is a fabric substrate, or an open-type or closed-type foam substrate, or an elastic silicone material.

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