Flexible sensor fusing proximity sense and touch sense sensing

Abstract

The invention relates to a flexible sensor fusing proximity sense and touch sense sensing, which comprises a bimodal sensing device, and the bimodal sensing device adopts a vertical stacking structure and comprises a sensing layer, a first insulating layer, a shielding layer, a second insulating layer and a proximity sense sensing layer which are arranged from top to bottom; the tactile sensing layer is made of metal or a conductive material; the first insulating layer and the second insulating layer are made of non-conductive flexible materials; the shielding layer is made of a metal net or a metal film; the proximity sense sensing layer is a piezoresistive touch sense sensing layer. According to the invention, a resistance touch technology and a capacitance proximity technology are combined, and dual-mode sensing, namely long-distance proximity obstacle avoidance and high-precision touch grabbing, is realized. The flexible design adapts to all parts of the robot, and adaptability is improved. The real-time data fusion capability is realized, and the perception information is optimized to support rapid decision making. The innovative technology combination guarantees high performance and controls cost, and wide application of the robot is promoted.

Description

Technical Field

[0001] This invention relates to the field of flexible sensing technology, and more specifically to a flexible sensor that integrates proximity and tactile sensing. Background Technology

[0002] With the development of robotics technology, intelligentization has become a trend, and sensor technology is the foundation for achieving this. Tactile and proximity sensors are widely used in robotic arms, but single sensor information is limited and easily affected by performance. Therefore, intelligent robots are typically equipped with multiple sensors to meet detection needs. Processing information from each sensor individually not only increases workload but also disrupts the connections between information, wasting resources. By fusing tactile and proximity signals, the local information from multiple sensors can be integrated, eliminating redundancy and contradictions, reducing uncertainty, and forming a more complete perception of the environment, thereby improving the accuracy of decision-making and reaction speed. Flexible sensors can conform to the robot's surface, and high-resolution tactile and high-detection-distance proximity sensors can fully acquire environmental information, helping the robot react promptly. Multi-sensor information fusion technology has become a key aspect of intelligent robot research.

[0003] Currently, many scholars have conducted research on multi-sensor fusion, especially tactile and proximity fusion. In 2013, Dirk Goger et al. proposed a tactile proximity sensor for use on robots. Both its tactile and proximity sensing are capacitive, and the Hammerstein-Wiener-Model is used for interpolation or calibration. [2] Similarly, in 2014, Stefan Escaida Navarro et al. proposed a capacitive proximity-tactile sensor that can be mounted on a robot gripper. [7] In 2016, Hosam Alagi et al. proposed a sensor that combines self-capacitive proximity sensing and mutual-capacitive tactile sensing modes, which can realize multi-modal fusion of tactile and proximity sensing, and the proximity sensing detection distance reaches 100 mm. These studies have promoted the development of proximity and tactile fusion applications, but there is still a lack in flexible applications, so it is difficult to deploy on complex surfaces.

[0004] Subsequently, in 2017, Il-Joo Cho et al. proposed a flexible integrated safety sensor for human-friendly robots, combining an ultrasonic proximity sensor and a piezoelectric tactile sensor, aiming to achieve long-distance proximity detection and fast tactile response to improve the safety of robot-human interaction. The detection distance reached 350 mm, and the functions of proximity and touch were inherited in a single flexible module. In 2020, Julián Castellanos-Ramos et al. proposed a multimodal tactile and proximity sensor based on off-the-shelf force resistors (FSR) and programmable system-on-a-chip (PSoC), which only utilizes the electrode structure of the force resistor to achieve proximity, with high space utilization. In 2024, Satoshi Tsuji proposed a freely customizable self-capacitive pure capacitor scheme to achieve proximity and touch [6]. These studies have proposed a variety of proximity and touch schemes, including applications of flexible sensing. However, they are limited by materials or detection distance. It is difficult to promote them on a large scale in existing robots.

[0005] However, the aforementioned existing technologies have some objective drawbacks.

[0006] 1. Limitations of rigid sensors: Due to their physical characteristics, traditional rigid sensors are difficult to fully conform to the complex shape of an object's surface, which may result in inaccurate measurement of capacitance or contact force at certain contact points.

[0007] 2. Durability and reliability: In complex and ever-changing working environments, traditional pure capacitive proximity tactile sensors may be damaged or fail due to vibration, impact or temperature changes, affecting the normal sensing of the sensor.

[0008] 3. Cost issues: High-precision and high-reliability sensors are often expensive, increasing manufacturing costs.

[0009] 4. Performance issues: Currently, it is difficult for proximity tactile sensors to achieve both high tactile resolution and high proximity sensing sensitivity. Summary of the Invention

[0010] The purpose of this invention is to provide a flexible sensor that integrates proximity sensing and tactile sensing.

[0011] To achieve the above objectives, the present invention provides the following technical solution:

[0012] A flexible sensor integrating proximity and tactile sensing includes a dual-modal sensing device. The dual-modal sensing device adopts a vertically stacked structure and includes, from top to bottom, a sensing layer, a first insulating layer, a shielding layer, a second insulating layer, and a proximity sensing layer. The first and second insulating layers are made of non-conductive flexible materials. The proximity sensing layer is a piezoresistive tactile sensing layer.

[0013] Preferably, the tactile sensing layer is made of metal or a conductive material.

[0014] Preferably, the shielding layer is made of a metal mesh or a metal film.

[0015] Beneficial effects

[0016] 1. Dual-modal perception: By combining resistive tactile perception and capacitive proximity perception technologies, the sensing device provided by this patent can combine tactile and proximity perception on specific complex surfaces. It can have a longer sensing distance to achieve obstacle avoidance based on proximity perception, or improve the grasping strategy through proximity perception pre-sensing to achieve more accurate grasping; it also has high-resolution tactile perception to achieve tactile grasping strategies.

[0017] 2. Flexibility and adaptability: The use of flexible sensors allows the device to better adapt to shape changes in various parts of the robot; ensuring that it can be installed on most surfaces. This flexibility greatly improves the robot's adaptability and operational performance in different scenarios.

[0018] 3. Real-time data processing: The device of this patent has powerful data processing capabilities, which can fuse and optimize data from different sensors in real time, thereby providing more accurate and timely perception information and supporting the robot's rapid decision-making and response.

[0019] 4. Cost-effectiveness: Through innovative combination of sensing technologies and data processing methods, this patent achieves high-performance perception while also considering cost-effectiveness; this allows the device to improve robot performance while maintaining reasonable manufacturing costs, which helps promote the application of robots in a wider range of fields.

[0020] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the interlayer structure of the main body of the present invention;

[0022] Figure 2 This is a schematic diagram of the self-capacitance proximity sensing capacitor of the present invention;

[0023] Figure 3 Fig. 5 shows a schematic diagram of the capacitor of this invention;

[0024] Figure 4 Fig. 5 shows a schematic diagram of the capacitor of this invention;

[0025] Figure 5 This is a schematic diagram of the sensor capacitance of the present invention;

[0026] Figure 6 This is a simplified schematic diagram of the sensor capacitance of the present invention;

[0027] Figure 7 This invention incorporates capacitance diagrams at different distances using common numerical values.

[0028] Figure 8 This is a capacitance diagram aligned to the origin according to the present invention. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of the present invention, it should be noted that unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art will understand the specific meaning of the above terms in this invention according to the specific circumstances. Furthermore, the technical features involved in the different embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0030] like Figure 1As shown, a flexible sensor integrating proximity and tactile sensing includes a dual-modal sensing device. The dual-modal sensing device adopts a vertically stacked structure, comprising, from bottom to top, a tactile sensing layer, a first insulating layer, a shielding layer, a second insulating layer, and a proximity sensing layer. The tactile sensing layer is made of metal or conductive material and is electrically connected to an LC circuit, providing proximity sensing results based on the capacitance between the measured object and ground. The first and second insulating layers are made of non-conductive flexible material, used to isolate DC current between the tactile sensing layer and the shielding layer, and also to prevent direct conduction between the shielding layer and the proximity sensing layer. The shielding layer achieves equipotentiality between the proximity electrodes and the shielding layer through a circuit, eliminating parasitic capacitance between them and the proximity sensing layer, while also isolating interference from the scanning current of the tactile layer. The bottom layer is a piezoresistive tactile sensing layer, which is formed by printing microstructured piezoresistive material on a layer of PET material and then connecting it to an FPC electrode. To accommodate multi-pixel requirements, a row-column cross wiring method is used, activating sensor units column by column and reading signals in a time-division multiplexing manner.

[0031] Preferably, the tactile sensing layer is made of metal or a conductive material.

[0032] Preferably, the shielding layer is made of a metal mesh or a metal film, and is made of a material with good electrical conductivity.

[0033] Working principle:

[0034] 1. Proximity principle

[0035] like Figure 2

[0036] In self-capacitance proximity sensing, each electrode inherently forms a capacitance with respect to ground. This capacitance is determined by the electrode's structure, the dielectric properties of the surrounding medium, and the spatial distance between the electrode and ground. When no object is nearby, the capacitance between the electrode and ground remains at a baseline. However, when a detected object (such as a finger) approaches, the parasitic capacitance between the electrode and ground increases. This capacitance can be detected by incorporating a sensing module, such as an LC module, into the circuit. This increase in parasitic capacitance is the basis for the higher sensitivity achieved when self-capacitance is combined with tactile sensing.

[0037] 2. Principles of tactile perception:

[0038] The perception is caused by the change in resistance due to the change in contact force, and then the tactile signal is obtained through the activation of the cross-wiring of rows and columns.

[0039] 3. The principle of enhanced proximity sensation caused by multimodal sensory overlay

[0040] As mentioned above, capacitive sensors detect target objects by relying on changes in the electric field between electrodes. If a conductive piezoresistive tactile pad (such as metal or conductive material) is present beneath the electrodes, parasitic capacitance will form. The specific effects manifest as static and dynamic interference. Static interference occurs because the piezoresistive tactile pad, acting as a conductor, may alter the initial electric field distribution of the capacitive sensor, causing a shift in the reference capacitance value (similar to fixed background noise). Dynamic interference occurs because when the piezoresistive pad deforms under force or the scanning current changes, its conductivity (such as resistivity) may fluctuate, further causing dynamic changes in parasitic capacitance. This change is superimposed on the target signal of the capacitive sensor, causing a change in the equivalent dielectric constant, and consequently, a change in the measurement range and sensitivity. The specific formula derivation is as follows:

[0041] Assume C1 is the capacitance between the palm or human body and the ground, C2 is the capacitance between the proximity sensor and the ground, C3 is the capacitance between the palm and the proximity sensor, C4 is the capacitance between the proximity sensor and the tactile sensor, C5 is the capacitance between the tactile sensor and the ground, and C6 is the capacitance between the palm and the tactile sensor.

[0042] like Figure 3 and Figure 4

[0043] The capacitance expression without a touch sensor is:

[0044]

[0045] Where C' can be simplified as follows Figure 5 The capacitance values ​​at terminals A and B can be equivalently represented using the triangular Y-transform of the capacitive reactance as follows: Figure 6 C15 and C0 are connected in series, and C' = C15*C0 / (C15+C0); where

[0046] C15= (C1*C5+ C1*C6+ C5*C6) / C6;

[0047] C16 = (C1*C5+ C1*C6+ C5*C6) / C5;

[0048] C56 =(C1*C5+ C1*C6+ C5*C6) / C1;

[0049]

[0050] remember

[0051]

[0052]

[0053] In common scenarios involving close proximity to the human body, the capacitance between the human body and ground is typically 100pF, i.e., C1=100 pF, C2=1pF, C4=20 pF, C5=1 pF, or similar values, such as... Figure 7 and Figure 8 ,in Figure 7 and Figure 8 The red curve represents the addition of a tactile layer, while the blue curve represents the absence of a tactile layer.

[0054] That is, the proximity sensitivity with a tactile sensor is greater than the proximity sensitivity without a tactile sensor.

[0055] This bimodal device has been experimentally used in obstacle avoidance and tactile command operation of robotic arms. The distance to obstacles can be obtained by the change of proximity readings, and different operation commands can be obtained by the changes of tactile pixels and their values.

[0056] In summary

[0057] This invention addresses the shortcomings of existing dual-modal sensing technologies of proximity and touch by combining piezoresistive tactile sensing and self-capacitive flexible sensing technologies. It provides a more efficient, accurate, and reliable dual-modal sensing device. Specifically, this invention employs a vertical stacking structure, increasing space utilization. By modifying material properties, attributes such as range and sensitivity can be adjusted. The effect of this structure is based on mathematical derivation, significantly amplifying the range and sensitivity of the proximity sensor using a tactile sensor. Furthermore, this stacking effectively preserves the flexible function, employing multiple shielding layers, insulating layers, electrode layers, and tactile layers to produce an amplified sensing effect.

[0058] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0059] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A flexible sensor that fuses proximity and tactile sensing, characterized in that, The application relates to a bimodal sensor device, which comprises a vertically-stacked structure, and comprises, from top to bottom, a sensing layer, a first insulating layer, a shielding layer, a second insulating layer and a proximity sensing layer; the first insulating layer and the second insulating layer are made of non-conductive flexible materials; and the proximity sensing layer is a piezoresistive touch sensing layer.

2. The flexible sensor fusing proximity sense and tactile sense according to claim 1, wherein, The touch sensing layer is made of metal or conductive material.

3. The flexible sensor that fuses proximity sense with tactile sense sensing of claim 1, wherein, The shielding layer is made of metal mesh or metal film.

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