A dual-mode flexible sensing system for finger pressure and posture

Abstract

The present invention belongs to a finger pressure and posture dual-mode flexible sensing system, comprising a pressure sensing unit for detecting finger pressure and an inertial sensor electrically connected to the pressure sensing unit for detecting finger posture. The pressure sensing unit is combined with the inertial sensor to detect the pressure and posture information of the finger respectively, and the movement information of the finger is identified by the pressure and posture information, which has the advantage of high accuracy.

Description

Technical Field

[0001] The invention belongs to the field of measurement and testing, and in particular relates to a finger pressure and posture dual-mode flexible sensing system. Background Art

[0002] The human hand is one of the most complex and dexterous organs in the human body, and plays a vital role in our daily activities, such as completing daily actions such as writing, typing, and grasping objects. Hand kinematics analysis technology is widely used in the fields of sports rehabilitation, sports biomechanics, and human-computer interaction. Among them, hand kinematics mainly exhibits two characteristics: fingertip pressure and finger posture. When performing a grasping action, a complete hand movement not only involves the pressure of the fingertips, but also the movement posture of each finger. Therefore, dual-modal monitoring of fingertip pressure and finger movement posture is crucial for hand state assessment. In addition, when grasping objects of different shapes, sizes, or materials, different areas of the fingertips are often subjected to different forces, so an array pressure sensor is needed to characterize the force on the fingertips. In addition, since the movement of the hand joints has the characteristics of multiple degrees of freedom, the three-dimensional movement of the fingers can be detected by the posture sensor, which can more comprehensively characterize the movement of the hand.

[0003] At present, a large number of hand motion sensing devices are mainly aimed at single fingertip pressure measurement or single finger gesture measurement. Among them, the mainstream fingertip pressure measurement method usually uses a single-point pressure sensor for detection, but these measurement methods often cannot characterize the force conditions in different areas of the fingertip. For gesture measurement methods, currently only single-degree-of-freedom measurements of finger joints can be performed, and multiple degrees of freedom cannot be measured simultaneously. Summary of the invention

[0004] The present invention aims to overcome the deficiencies in the prior art and provide a finger pressure and posture dual-mode flexible sensing system.

[0005] The object of the present invention is achieved as follows: a finger pressure and posture dual-mode flexible sensing system includes a pressure sensing unit for detecting finger pressure and an inertial sensor electrically connected to the pressure sensing unit for detecting finger posture.

[0006] Preferably, the pressure sensing unit can be bent to fit the finger when electrically connected to the inertial sensor, and can be straightened when separated from the inertial sensor.

[0007] Preferably, two inertial sensors are provided, namely a first inertial sensor and a second inertial sensor. The first inertial sensor is attached to the middle phalanx of the finger, and the second inertial sensor is attached to the proximal phalanx of the finger. The first inertial sensor and the second inertial sensor are electrically connected and then output.

[0008] Preferably, the finger pressure and posture dual-modal flexible sensing system further includes a flexible circuit structure, and the first inertial sensor and the second inertial sensor are arranged on the flexible circuit structure.

[0009] Preferably, the pressure sensing unit includes a base layer, a wire layer, a sensing layer and a packaging layer. The wire layer is arranged on one side of the base layer to electrically connect the sensing layer to the first inertial sensor. The packaging layer covers the upper side of the sensing layer and the wire layer to encapsulate the sensing layer and the wire layer on the base layer.

[0010] Preferably, the wire layer includes wires and electrodes electrically connected to the wires, the electrodes include input electrodes and output electrodes, one end of a wire is electrically connected to the input electrode, and the other end thereof is electrically connected to a contact electrode of the first inertial sensor; one end of another wire is electrically connected to the output electrode, and the other end thereof is electrically connected to another contact electrode of the inertial sensor; the input electrode and the output electrode are electrically connected to the sensing layer.

[0011] Preferably, the base layer is a flexible film material or an elastic film material with extensibility.

[0012] Preferably, the base layer, the conductor layer, the packaging layer and the flexible circuit structure are all arranged in a serpentine manner.

[0013] Preferably, the encapsulation layer is a flexible material with elasticity or stretchability.

[0014] Preferably, the sensing layer is a piezoresistive, capacitive or piezoelectric force sensitive material.

[0015] The present invention has the following positive effects: combining a pressure sensing unit with an inertial sensor to respectively detect the pressure and posture information of a finger, and identifying the movement information of the finger from the pressure and posture information, which has the advantage of high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall assembly of the pressure sensing unit and the inertial sensor of the present invention;

[0017] Figure 2 It is a schematic structural diagram of the dispersed display of the pressure sensing unit of the present invention;

[0018] Figure 3 A schematic structural diagram of a conductor layer of a pressure sensing unit of the present invention;

[0019] Figure 4 A schematic diagram of the back side of the inertial sensor of the present invention;

[0020] Figure 5 The working principle diagram of the sensing layer of the present invention;

[0021] Figure 6 The working principle diagram of the inertial sensor of the present invention;

[0022] Figure 7 A schematic diagram of the deployment of the back of the hand of the present invention;

[0023] Figure 8 A schematic diagram of the deployment of the hand front of the present invention. DETAILED DESCRIPTION

[0024] Embodiment 1, as Figures 1 to 8 A finger pressure and posture dual-mode flexible sensing system is shown, comprising a pressure sensing unit 10 for detecting finger pressure and an inertial sensor electrically connected to the pressure sensing unit 10 for detecting finger posture. The pressure sensing unit 10 can be bent to fit the finger when electrically connected to the inertial sensor, and can be straightened when separated from the inertial sensor.

[0025] The pressure sensing unit 10 can be used to detect the pressure distribution when an object contacts the fingertips, and has overall ductility. After curling, it can adapt to different finger sizes and shapes, and can be attached to the fingertips of the thumb, index finger, middle finger, ring finger and little finger. It has a high measurement factor, excellent sensing resolution and good repeatability. The inertial sensor can be attached to the middle phalanx and proximal phalanx of the thumb, index finger, middle finger, ring finger and little finger respectively to detect the posture of each finger joint. The posture information includes joint angle, Euler angle, angular velocity, angular acceleration and gravity acceleration.

[0026] The pressure sensing unit 10 includes a base layer 101, a wire layer 102, a sensing layer 103 and a packaging layer 104. The wire layer 102 is arranged on one side of the base layer 101 to electrically connect the sensing layer 103 to the first inertial sensor 201. The packaging layer 104 covers the upper side of the sensing layer 103 and the wire layer 102 to package the sensing layer 103 and the wire layer 102 on the base layer 101. The base layer 101, the wire layer 102, the packaging layer 104 and the flexible circuit structure 30 are all arranged in a serpentine manner.

[0027] The inertial sensor is provided with two, namely a first inertial sensor 201 and a second inertial sensor 202. The first inertial sensor 201 is attached to the middle phalanx of the finger, and the second inertial sensor 202 is attached to the proximal phalanx of the finger. The first inertial sensor 201 and the second inertial sensor 202 are electrically connected and output. The inertial measurement unit can be a three-axis, six-axis or nine-axis measurement unit. Preferably, a nine-axis measurement unit is integrated on the front side of the flexible circuit structure 30.

[0028] The base layer 101 is a flexible film material or an elastic film material with ductility. One side of the base layer 101 fits the fingertip. When the pressure sensing unit 10 contacts an object, the resistance of the force-sensitive material in the sensing layer 103 changes, and the pressure value is determined according to the resistance change rate.

[0029] The wire layer 102 includes wires and electrodes electrically connected to the wires, and the electrodes include an input electrode 1022 and an output electrode 1021. One end of a wire is electrically connected to the input electrode 1022, and the other end thereof is electrically connected to a contact electrode 2011 of the first inertial sensor 201; one end of another wire is electrically connected to the output electrode 1021, and the other end thereof is electrically connected to another contact electrode 2011 of the first inertial sensor 201; the input electrode 1022 and the output electrode 1021 are electrically connected to the sensing layer 103.

[0030] The wire layer 102 can be filled with solid metal, liquid metal or ions with conductive properties, preferably metal gold is used as the conductive material, and is closely attached to the base layer 101. When bending and stretching, the wire layer 102 and the base layer 101 can be deformed together. The wire layer 102 is made by magnetron sputtering to attach gold material to the base layer 101, and is closely attached to the sensing layer 103 and the packaging layer 104.

[0031] The wire layer 102 further includes a contact electrode sheet 105 connected to the flexible circuit structure 30. The contact electrode sheet 105 is preferably a gold finger.

[0032] There are five electrodes, namely a middle electrode, an upper electrode, a lower electrode, a left electrode and a right electrode, and there are six wires, one end of five of which are electrically connected to the output electrodes 1021 of the middle electrode, the upper electrode, the lower electrode, the left electrode and the right electrode, respectively, and the other ends thereof are electrically connected to the five contact electrodes 2011 of the first inertial sensor 201, and one end of another wire is electrically connected to the input electrode 1022 of the middle electrode, the upper electrode, the lower electrode, the left electrode and the right electrode, and the other end thereof is electrically connected to another contact electrode 2011 of the first inertial sensor 201.

[0033] The five electrodes in contact with the graphene aerogel are designed into two semicircular structures, the purpose of which is that: during the foaming process of the aerogel, it will show a hemispherical uniform expansion, and the two semicircular electrode designs can just fit the hemispherical aerogel completely, reducing the system noise caused by the poor contact between the electrode and the graphene aerogel. Among the five electrodes, one of the semicircular electrodes of each electrode is connected together as the input electrode 1022 of the excitation voltage of the graphene aerogel, and the other semicircular electrode is used as the output electrode 1021 of the graphene aerogel sensing signal. The excitation voltage input electrode 1022 and the output electrode 1021 of the sensing signal are both connected to six gold fingers. The role of the gold finger is to be able to connect to the contact electrode 2011 on the back of the first inertial sensor 201, and lead the sensing signal of the graphene aerogel to the signal processing unit 40 through the circuit of the inertial sensor.

[0034] The sensing layer 103 is a piezoresistive, capacitive or piezoelectric force-sensitive material. Preferably, resistive graphene aerogel is used as the force-sensitive material, and the five electrodes of the wire layer 102 are bonded by conductive silver glue. A plurality of sensing layers 103 can be provided. Through the liquid graphene aerogel glue dripping technology, five sensing units are formed on the upper electrode, middle electrode, lower electrode, left electrode and right electrode of the wire layer 102. The dried graphene aerogel has force-sensitive properties and can characterize the force conditions of the upper, middle, lower, left and right areas of the fingertips.

[0035] The packaging layer 104 is a flexible material with elasticity or stretchability. The packaging layer 104 encapsulates and wraps the base layer 101, the wire layer 102, and the sensing layer 103 as a whole, and can achieve the purpose of overall extensibility and bendability.

[0036] Preferably, the base layer 101 and the encapsulation layer 104 are both made of polydimethylsiloxane (PDMS) film materials with ductility.

[0037] like Figure 5 As shown, the sensing layer adopts a multi-channel voltage-dividing circuit structure. The five sensing layers U, L, R, C, and D are respectively connected in series with five voltage-dividing resistors R0, R1, R2, R3, and R4 to form a separate sensing path, and each sensing path is independently powered. The signal lines S0 to S4 of the sensing path are connected to the digital-to-analog conversion circuit for signal acquisition. The voltage signal of each sensing unit is expressed as follows:

[0038]

[0039] Among them, U signal is the output signal of the sensing layer, U in is the input excitation voltage, R xis the resistance of the sensing layer, R d is the resistance value of the voltage divider resistor. When the sensing layer is pressurized, R x The resistance will change and the output voltage will change accordingly. Therefore, the pressure sensing layer can be used to characterize the force conditions of the fingertip pressure.

[0040] like Figure 6 As shown, each inertial sensor has three mutually orthogonal self-coordinates P, which will form an angle with the absolute coordinate system P' during the rotation process, usually expressed in Euler angles. The yaw angle is formed between the inertial sensor's own coordinate Py and the absolute coordinate P'y', the roll angle is between Px and P'z', and the pitch angle is between Py and P'z'. Each inertial sensor can output a set of quaternions, and its quaternion representation method is as follows:

[0041] Q=q0+q1·i+q2·j+q3·k

[0042] Among them: q0, q1, q2, q3 represent the real part of the quaternion, i, j, q represent the imaginary part of the quaternion.

[0043] In order to describe the attitude of each inertial sensor, the quaternion usually needs to be converted into Euler angles. The conversion relationship is shown in the following formula:

[0044]

[0045] Where: α, β, γ represent the pitch angle, roll angle and yaw angle respectively.

[0046] The finger pressure and posture dual-mode flexible sensing system also includes a flexible circuit structure 30, on which the first inertial sensor 201 and the second inertial sensor 202 are arranged. The first inertial sensor 201 and the second inertial sensor 202 are connected to the flexible circuit structure 30 by means of electronic component patches. The flexible circuit structure 30 can adopt a meandering structure or a redundant structure, preferably a redundant structure, so that such a circuit structure will not affect the bending of human fingers. The back side also includes a contact electrode 2011 connected to the wire layer 102.

[0047] The pressure sensing unit 10 and the inertial sensor constitute a dual-mode detection unit for a finger. There are five such dual-mode detection units. The pressure sensing unit 10 is attached to the fingertips of the thumb, index finger, middle finger, ring finger and little finger respectively. The inertial sensors are attached to the middle phalanx and proximal phalanx of the thumb, index finger, middle finger, ring finger and little finger respectively.

[0048] The second inertial sensor 202 is electrically connected to the signal processing unit 40, and the signal processing unit 40 is uniformly connected to the five groups of bimodal detection units for collecting, analyzing and transmitting bimodal signal data of the hand.

[0049] like Figure 7 and Figure 8 As shown, the pressure sensing unit 10 is combined with an inertial sensor to detect the pressure and posture information of the finger respectively, and the movement information of the finger is identified by the pressure and posture information, which has the advantage of high accuracy. It can be extended to other applications involving hand movement, including biological signal monitoring, human-machine interface, and bio-robots.

[0050] The above examples are only preferred examples of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A finger pressure and posture dual-mode flexible sensing system, characterized in that: It includes a pressure sensing unit for detecting finger pressure, and an inertial sensor electrically connected to the pressure sensing unit for detecting finger posture; The pressure sensing unit includes a base layer, a wire layer, a sensing layer and a packaging layer, wherein the wire layer is arranged on one side of the base layer to electrically connect the sensing layer to the first inertial sensor, and the packaging layer covers the upper side of the sensing layer and the wire layer to package the sensing layer and the wire layer on the base layer; The base layer, the conductor layer, the packaging layer and the flexible circuit structure are all arranged in a serpentine manner; The conductor layer is filled with solid metal, liquid metal or ions with conductive properties, and is closely attached to the base layer. When bending and stretching occur, the conductor layer and the base layer can be deformed together; The conductor layer is made by attaching gold material to the base layer through magnetron sputtering, and is closely attached to the sensing layer and the packaging layer; The wire layer includes wires and electrodes electrically connected to the wires, the electrodes include input electrodes and output electrodes, one end of a wire is electrically connected to the input electrode, and the other end thereof is electrically connected to a contact electrode of the first inertial sensor; one end of another wire is electrically connected to the output electrode, and the other end thereof is electrically connected to another contact electrode of the first inertial sensor; the input electrode and the output electrode are electrically connected to the sensing layer; the sensing layer uses resistive graphene aerogel as a force sensitive material; The conductor layer also includes a contact electrode sheet connected to the flexible circuit structure; the contact electrode sheet is a gold finger; There are five electrodes, namely a middle electrode, an upper electrode, a lower electrode, a left electrode and a right electrode, and six wires, wherein one end of five of the wires is electrically connected to the output electrodes of the middle electrode, the upper electrode, the lower electrode, the left electrode and the right electrode, respectively, and the other end thereof is electrically connected to the five contact electrodes of the first inertial sensor, and one end of another of the wires is electrically connected to the input electrodes of the middle electrode, the upper electrode, the lower electrode, the left electrode and the right electrode, and the other end thereof is electrically connected to another contact electrode of the first inertial sensor; The five electrodes in contact with the graphene aerogel form two semicircular structures. Among the five electrodes, one semicircular electrode of each electrode is connected together as an input electrode of the excitation voltage of the graphene aerogel, and the other semicircular electrode is used as an output electrode of the graphene aerogel sensing signal; the excitation voltage input electrode and the sensing signal output electrode are both connected to the six gold fingers.

2. The finger pressure and posture dual-mode flexible sensing system according to claim 1, characterized in that: The pressure sensing unit can be bent to fit the finger when electrically connected to the inertial sensor, and can be straightened when separated from the inertial sensor.

3. The finger pressure and posture dual-mode flexible sensing system according to claim 1, characterized in that: The inertial sensors are provided with two, namely a first inertial sensor and a second inertial sensor. The first inertial sensor is attached to the middle phalanx of the finger, and the second inertial sensor is attached to the proximal phalanx of the finger. The first inertial sensor and the second inertial sensor are electrically connected and then output.

4. The finger pressure and posture dual-mode flexible sensing system according to claim 1, characterized in that: The finger pressure and posture dual-mode flexible sensing system further includes a flexible circuit structure, and the first inertial sensor and the second inertial sensor are arranged on the flexible circuit structure.

5. The finger pressure and posture dual-mode flexible sensing system according to claim 4, characterized in that: The base layer is a flexible film material or an elastic film material with extensibility.

6. The finger pressure and posture dual-mode flexible sensing system according to claim 4, characterized in that: The packaging layer is a flexible material with elasticity or stretchability.

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