Flexible Tactile Sensor for Medical Rehabilitation Robots

Abstract

The flexible tactile sensor for medical rehabilitation robots belongs to the field of tactile perception of medical robots. It solves the problems of hysteresis in dynamic measurement data acquisition and low measurement accuracy of piezoresistive flexible tactile sensors under the conditions of meeting dynamic and static measurements. In the present invention, piezoelectric and piezoresistive sensitive units are alternately arranged to form a large-range array sensing area. During specific application, the corresponding two piezoelectric sensitive units or the corresponding piezoresistive sensitive units that form an interlock can be gated by relying on the upper piezoelectric gating layer and the lower piezoelectric gating layer to complete the output of tactile signals; the piezoelectric sensitive units and the piezoresistive sensitive units are arranged to be composed of a closely arranged hemispherical array. The present invention is mainly applied to robots in medical rehabilitation scenarios.

Description

Technical Field

[0001] The present invention belongs to the field of tactile perception of medical robots. Background Art

[0002] Robotics consists of the following five key enabling technologies: mechanism, sensing, control, artificial intelligence, and human-machine interaction technology. Sensor technology is the prerequisite for robot control, interaction, and intelligence, and is the basis for robots to perceive the environment and complete tasks.

[0003] Touch is an important form of perception for organisms to obtain external information. It is an important form of perception for robots to obtain environmental information, second only to vision. Moreover, the tactile modality has more advantages in local precise perception. It is a necessary medium for robots to directly interact with the external environment. Especially in the application scenarios of medical robots, higher requirements are put forward for tactile information and the safety of the human-machine contact process.

[0004] The amount of information that a tactile sensor can perceive is very large. It not only reflects the interaction between the robot and the environment, but also reflects various physical properties of the contacted target, such as position, shape, stiffness, softness, texture, thermal conductivity, viscosity, etc. In the research of machine intelligent perception, there are more studies on visual perception. Machine tactile perception technology is easier to obtain the attribute information of objects, can process data information more efficiently, make up for the deficiencies of audio-visual interaction information, and ensure human-machine safety at the same time.

[0005] Flexible tactile sensors are easy to fit irregular surfaces such as the skin, and have better wearing comfort than rigid sensors. They play an important role in the fields of human-machine interaction, medical devices, wearable devices, health monitoring, etc. Therefore, the research on flexible tactile sensors has important significance.

[0006] Traditional flexible tactile sensors adopt piezoelectric or piezoresistive principles. The piezoelectric type cannot meet the measurement requirements of non-dynamic forces and can only be applied in dynamic measurement scenarios with low measurement accuracy; although the piezoresistive type can achieve measurements in both dynamic and static scenarios, there are problems such as data acquisition hysteresis during dynamic measurement affecting subsequent data applications, high power consumption, and low measurement accuracy. Therefore, how to solve the problems of eliminating dynamic measurement data acquisition hysteresis and improving measurement accuracy under the conditions that piezoresistive flexible tactile sensors meet dynamic and static measurements needs to be urgently solved. Summary of the Invention

[0007] The purpose of the present invention is to solve the problems of dynamic measurement data acquisition hysteresis and low measurement accuracy of piezoresistive flexible tactile sensors under the conditions of meeting dynamic and static measurements. The present invention provides a flexible tactile sensor for medical rehabilitation robots.

[0008] A flexible tactile sensor for a medical rehabilitation robot, comprising an upper piezoelectric gating layer, an upper force-sensitive layer, a lower force-sensitive layer, and a lower piezoelectric gating layer arranged in sequence from top to bottom;

[0009] The upper force-sensitive layer and the lower force-sensitive layer are relatively arranged and in contact with each other, and a conductive material is sprayed on their contact surfaces; both the upper force-sensitive layer and the lower force-sensitive layer are composed of an array formed by alternating N columns of piezoelectric sensitive units and N columns of piezoresistive sensitive units, and the N columns of piezoelectric sensitive units of the upper force-sensitive layer are relatively arranged with the N columns of piezoelectric sensitive units of the lower force-sensitive layer, and the N columns of piezoresistive sensitive units of the upper force-sensitive layer are relatively arranged with the N columns of piezoresistive sensitive units of the lower force-sensitive layer; N is an integer;

[0010] All the piezoelectric sensitive units and piezoresistive sensitive units on the upper force-sensitive layer are arranged on the gating nodes distributed in an array on the upper piezoelectric gating layer; all the piezoelectric sensitive units and piezoresistive sensitive units on the lower force-sensitive layer are arranged on the gating nodes distributed in an array on the upper piezoelectric gating layer;

[0011] Both the piezoelectric sensitive units and the piezoresistive sensitive units are composed of a closely arranged hemispherical array, and the hemispheres on the relatively arranged piezoelectric sensitive units and the hemispheres on the relatively arranged piezoresistive sensitive units are staggered from each other, so that when the hemispherical arrays on the relatively arranged piezoelectric sensitive units and the hemispherical arrays on the relatively arranged piezoresistive sensitive units are squeezed, they all form an interlock.

[0012] Preferably, the flexible tactile sensor for a medical rehabilitation robot further comprises two symmetrically arranged flexible base layers;

[0013] The two flexible base layers are respectively pasted on the upper surface of the upper piezoelectric gating layer and the lower surface of the lower piezoelectric gating layer.

[0014] Preferably, the flexible base layer is made of a non-conductive material, PET material.

[0015] Preferably, the upper piezoelectric gating layer is composed of a first gating circuit formed by spraying conductive silver paste on a non-conductive substrate;

[0016] The gating nodes in the first gating circuit are arranged in an array on the non-conductive substrate, and each column of gating nodes is connected in series and led out as a signal terminal of the upper piezoelectric gating layer.

[0017] Preferably, the lower piezoelectric gating layer is composed of a second gating circuit formed by spraying conductive silver paste on a non-conductive substrate;

[0018] The gating nodes in the second gating circuit are arranged in an array on a non-conductive substrate. The gating nodes with odd serial numbers in each row of gating nodes are connected together and led out as one signal terminal of the lower piezoelectric gating layer, and the gating nodes with even serial numbers are connected together and led out as the other signal terminal of the lower piezoelectric gating layer.

[0019] Preferably, the conductive material sprayed on the hemispherical surfaces of the hemispherical arrays of the piezoelectric sensing units and the piezoresistive sensing units is graphene.

[0020] Preferably, the piezoelectric sensing units are made of PVDF material, and the piezoresistive sensing units are made of PDMS material.

[0021] Preferably, the piezoelectric sensing units are formed by photolithography on the surface of a layer of PVDF material to form a closely arranged hemispherical array.

[0022] Preferably, the piezoresistive sensing units are formed by photolithography on the surface of a PDMS material to form a closely arranged hemispherical array.

[0023] Preferably, the number of gating nodes on the upper piezoelectric gating layer and the lower piezoelectric gating layer is the sum of the numbers of all piezoelectric sensing units and all piezoresistive sensing units on the upper force sensing layer or the lower force sensing layer.

[0024] Principle analysis: In the present invention, piezoelectric and piezoresistive sensing units are alternately arranged to form a large-range array sensing area. In specific applications, the upper piezoelectric gating layer and the lower piezoelectric gating layer can be relied on to gate the corresponding two piezoelectric sensing units or the corresponding piezoresistive sensing units that form an interlock, complete the output of tactile signals, and subsequently rely on the signal processing module to complete the three-dimensional reconstruction of tactile information.

[0025] The beneficial effects brought by the present invention are:

[0026] In the present invention, the piezoelectric sensing units and the piezoresistive sensing units are arranged to be composed of closely arranged hemispherical arrays, and the hemispheres on the relatively arranged piezoelectric sensing units and the hemispheres on the relatively arranged piezoresistive sensing units are all staggered from each other, so that when the hemispherical arrays on the relatively arranged piezoelectric sensing units and the hemispherical arrays on the relatively arranged piezoresistive sensing units are squeezed against each other, they all form an interlock, increasing the mutual contact area between the hemispheres on the upper and lower relatively arranged piezoelectric sensing units or piezoresistive sensing units, and improving the measurement accuracy. The present invention can realize both dynamic and static measurements, and can ensure the measurement accuracy during both dynamic and static measurements. During dynamic measurement, the relatively arranged piezoelectric sensing units that form an interlock through gating are selected for measurement, overcoming the problem of data acquisition hysteresis.

[0027] The present invention mainly designs a flexible tactile sensor for a robot in a medical rehabilitation scenario, which can be used at the end of the robot or on a physician. For the specific application in cooperation with medical work, the flexible tactile sensor is made into a suitable shape and size and has a certain flexibility, facilitating the high sensitivity and high precision of the entire flexible tactile sensor during operation, and having strong adaptability to both dynamic and static scenarios; the overall structural design of the flexible tactile sensor of the present invention is simple and efficient, and has a wide range of application scenarios.

[0028] Compared with the prior art, the present invention:

[0029] 1. A flexible tactile sensor for medical rehabilitation of the present invention refines the microstructure of the sensitive element, adopts an interlocking structure of mutually hemispherical shapes, and further realizes the perception of three-dimensional forces while improving the measurement accuracy;

[0030] 2. The present invention uses an array-type sensing arrangement. Compared with traditional sensing methods, it further realizes more precise force perception and further realizes tactile perception including slip sensation, etc.;

[0031] 3. The present invention uses a combination of piezoelectric materials and piezoresistive materials. By arranging them alternately, it makes up for the shortcomings of traditional piezoelectric sensors in measuring non-dynamic forces and the defects of traditional piezoresistive sensors such as hysteresis and insufficient dynamic performance, and realizes the complementary advantages of the two;

[0032] 4. The overall structure of the present invention is simple, and common materials on the market are used, making the entire device have stable performance, simple structure, high reliability, and easy maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is an assembly drawing of the flexible tactile sensor for a medical rehabilitation robot described in the present invention;

[0034] Figure 2 is a relative position relationship diagram of the hemispherical arrays on the piezoelectric sensitive units 5 arranged oppositely on the upper force sensitive layer 2 and the lower force sensitive layer 3; wherein, Figure 2 a is a three-dimensional structure diagram of the piezoelectric sensitive units 5 arranged oppositely, Figure 2 b is Figure 2 the front view of a;

[0035] Figure 3 is a relative position relationship diagram of the hemispherical arrays on the piezoresistive sensitive units 6 arranged oppositely on the upper force sensitive layer 2 and the lower force sensitive layer 3; wherein, Figure 3 a is a three-dimensional structure diagram of the piezoresistive sensitive units 6 arranged oppositely, Figure 3 b is Figure 3 the front view of a;

[0036] Figure 4 It is a schematic structural diagram of the upper piezoelectric gating layer 1;

[0037] Figure 5 It is a schematic structural diagram of the piezoelectric sensing unit 5 and the piezoresistive sensing unit 6 pasted on the upper piezoelectric gating layer 1;

[0038] Figure 6 It is a schematic structural diagram of the lower piezoelectric gating layer 4;

[0039] Figure 7 It is a schematic structural diagram of the piezoelectric sensing unit 5 and the piezoresistive sensing unit 6 pasted on the lower piezoelectric gating layer 4;

[0040] Figure 8 It is a schematic diagram of the tactile perception of the tactile sensor of the present invention during the puncture process; wherein, Figure 8 a is a schematic structural diagram of the tactile sensor of the present invention attached to the clamping arm; Figure 8 b is a schematic diagram of the state of the clamping arm with the tactile sensor when clamping the puncture needle;

[0041] Figure 9 It is a schematic diagram of the tactile perception of the tactile sensor of the present invention during the massage process;

[0042] Figure 10 It is a schematic diagram of the charge change after the piezoelectric sensing units 5 that are interlocked and oppositely arranged are stressed;

[0043] Figure 11 It is a schematic diagram of the resistance change after the piezoresistive sensing units 6 that are interlocked and oppositely arranged are stressed. Detailed implementation manners

[0044] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0045] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0046] In order to solve the problems of hysteresis in dynamic measurement data acquisition and low measurement accuracy of piezoresistive flexible tactile sensors under the conditions of meeting dynamic and static measurements, the present invention starts from two aspects. First, aiming at the problem of hysteresis in dynamic measurement data acquisition of piezoresistive flexible tactile sensors, it is made to use the piezoelectric sensitive unit 5 for measurement through a gating method. For the problem of low measurement accuracy, the structures of the piezoelectric sensitive unit 5 and the piezoresistive sensitive unit 6 themselves and the states when the upper and lower relative sensitive units are in contact are improved, so that the upper and lower sensitive units form an interlock to increase the contact area and improve the measurement accuracy. Specifically as follows:

[0047] Referring to Figures 1 to 7 To illustrate this embodiment, the flexible tactile sensor for a medical rehabilitation robot described in this embodiment includes an upper piezoelectric gating layer 1, an upper force sensitive layer 2, a lower force sensitive layer 3, and a lower piezoelectric gating layer 4 arranged in sequence from top to bottom;

[0048] The upper force sensitive layer 2 and the lower force sensitive layer 3 are arranged opposite to each other and in contact, and a conductive material is sprayed on their contact surfaces; both the upper force sensitive layer 2 and the lower force sensitive layer 3 are composed of an array in which N columns of piezoelectric sensitive units 5 and N columns of piezoresistive sensitive units 6 are alternately arranged, and the N columns of piezoelectric sensitive units 5 in the upper force sensitive layer 2 are arranged opposite to the N columns of piezoelectric sensitive units 5 in the lower force sensitive layer 3, and the N columns of piezoresistive sensitive units 6 in the upper force sensitive layer 2 are arranged opposite to the N columns of piezoresistive sensitive units 6 in the lower force sensitive layer 3; N is an integer; all the piezoelectric sensitive units 5 and piezoresistive sensitive units 6 on the upper force sensitive layer 2 are arranged on the gating nodes with an array distribution on the upper piezoelectric gating layer 1; all the piezoelectric sensitive units 5 and piezoresistive sensitive units 6 on the lower force sensitive layer 3 are arranged on the gating nodes with an array distribution on the upper piezoelectric gating layer 1;

[0049] Both the piezoelectric sensitive unit 5 and the piezoresistive sensitive unit 6 are composed of a closely arranged hemispherical array, and the hemispheres on the relatively arranged piezoelectric sensitive units 5 and the hemispheres on the relatively arranged piezoresistive sensitive units 6 are all staggered from each other, so that when the hemispherical arrays on the relatively arranged piezoelectric sensitive units 5 and the hemispherical arrays on the relatively arranged piezoresistive sensitive units 6 are squeezed against each other, they all form an interlock.

[0050] During application, the number of piezoelectric sensitive units 5 in each column of piezoelectric sensitive units 5 is the same as the number of piezoresistive sensitive units 6 in each column of piezoresistive sensitive units 6. A conductive material is sprayed on the contact surface of the upper force sensitive layer 2 and the lower force sensitive layer 3, that is, a conductive material is sprayed on the upper and lower hemispherical arrays. Specifically, the conductive material is graphene, and the conductive material sprayed on the hemispherical surfaces of the hemispherical arrays of the piezoelectric sensitive unit and the piezoresistive sensitive unit is graphene, which increases the conductive effect.

[0051] Referring toFigure 1 The flexible tactile sensor for a medical rehabilitation robot further includes two symmetrically arranged flexible base layers 7; the two flexible base layers 7 are respectively pasted on the upper surface of the upper piezoelectric gating layer 1 and the lower surface of the lower piezoelectric gating layer 4. The purpose of setting the two flexible base layers 7 is to flexibly protect the whole formed by the upper piezoelectric gating layer 1, the upper force-sensitive layer 2, the lower force-sensitive layer 3 and the lower piezoelectric gating layer 4. Further, the flexible base layer 7 is made of a non-conductive material, PET material.

[0052] Moreover, the present invention designs a flexible tactile sensor for a robot in a medical rehabilitation scenario, which can be used at the end of the robot or on a physician. For the convenience of medical work, in specific applications, the flexible tactile sensor is made into a suitable shape and size and has a certain flexibility, so as to be highly sensitive and accurate during the operation of the whole flexible tactile sensor, and has strong adaptability to both dynamic and static scenarios; the structural design of the whole flexible tactile sensor of the present invention is simple and efficient, and has a wide range of application scenarios.

[0053] When the sensitive unit on the upper piezoelectric gating layer 1 and the piezoelectric sensitive unit 5 on the lower piezoelectric gating layer 4 are assembled, the hemispherical sides are relatively fitted together and form an interlocking structure. For details, see Figure 2 such that when the flexible tactile sensor is subjected to a normal force or a tangential force, the contact area of the interlocking structure changes, which in turn causes charge transfer in the sensitive material. See Figure 10 This provides an original signal for further realizing the measurement of three-dimensional forces in a dynamic situation, and it has the characteristics of high dynamic response and high-precision measurement of dynamic forces. At the same time, when the sensitive unit on the upper piezoelectric gating layer 1 and the piezoresistive sensitive unit 6 on the lower piezoelectric gating layer 4 are assembled, the hemispherical sides are relatively fitted together and form an interlocking structure. For details, see Figure 5 such that when the flexible tactile sensor is subjected to a normal force or a tangential force, the contact area of the interlocking structure changes, which in turn causes a change in the resistance value of the sensitive material. See Figure 11 This provides an original signal for further realizing the measurement of three-dimensional forces in a dynamic situation, and it can measure non-dynamic forces with high precision.

[0054] See Figure 4 The upper piezoelectric gating layer 1 is composed of a first gating circuit formed by spraying conductive silver paste on a non-conductive substrate; each gating node in the first gating circuit is arranged in an array on the non-conductive substrate, and each column of gating nodes is connected in series and then led out as a signal terminal of the upper piezoelectric gating layer 1.

[0055] See Figure 6, the lower piezoelectric gating layer 4 is composed of a second gating circuit formed by spraying conductive silver paste on a non-conductive substrate; each gating node in the second gating circuit is arranged in an array on the non-conductive substrate, and the gating nodes with odd serial numbers in the left-to-right direction in each row of gating nodes are connected simultaneously and led out as one signal terminal of the lower piezoelectric gating layer 4, and the gating nodes with even serial numbers are connected simultaneously and led out as the other signal terminal of the lower piezoelectric gating layer 4.

[0056] Furthermore, the piezoelectric sensing unit 5 is made of PVDF material, and the piezoresistive sensing unit 6 is made of PDMS material. The piezoelectric gating circuit composed of PVDF material and the piezoresistive gating circuit composed of PDMS material are independent of each other, so that force-sensitive materials based on different principles can output expected signals through the circuit.

[0057] See Figure 2 , the piezoelectric sensing unit 5 is made by photolithography on the surface of a layer of PVDF material to form a closely arranged hemispherical array.

[0058] See Figure 3 , the piezoresistive sensing unit 6 is made by photolithography on the surface of the PDMS material to form a closely arranged hemispherical array.

[0059] Furthermore, the number of gating nodes on the upper piezoelectric gating layer 1 and the lower piezoelectric gating layer 4 is the sum of the numbers of all piezoelectric sensing units 5 and all piezoresistive sensing units 6 on the upper force-sensitive layer 2 or the lower force-sensitive layer 3.

[0060] As Figure 8 shown, the present invention can be made into a size and shape suitable for a human finger and pasted on a finger or finger-like mechanism for puncture.

[0061] During the puncture process, one side of the flexible tactile sensor contacts the puncture needle and receives normal force and tangential force, and the other side is fixed to the finger. In this process, the normal force and the tangential force are sequentially transmitted through the flexible base layer made of flexible non-conductive material PET, the piezoelectric gating layer, and then conducted to the piezoelectric sensing unit 5 made of force-sensitive piezoelectric PVDF material with a lithographed spherical microstructure and a single-sided coating of conductive graphene and the piezoresistive sensing unit 6 made of force-sensitive piezoresistive PDMS material. Therefore, the force-sensitive piezoelectric PVDF material (i.e., the relatively arranged piezoelectric sensing units 5), and the force-sensitive piezoresistive PDMS material (i.e., the relatively arranged piezoresistive sensing units 6) respectively generate relative movement and extrusion;

[0062] During the process of changing the contact area of the PVDF material, the charges on both sides of the mutually contacting array piezoelectric PVDF materials change accordingly, and the signals generated during the dynamic process are transmitted to the external signal processing circuit through the upper piezoelectric gating layer 1 and the lower piezoelectric gating layer 4, completing the redrawing of the three-dimensional force signal and even further completing the redrawing of the entire dynamic process;

[0063] After the contact area of the PDMS material changes accordingly, the overall resistance of the mutually contacting array piezoresistive PDMS materials changes, and the signals generated during the dynamic process are transmitted to the external signal processing circuit through the array gating upper piezoelectric gating layer 1 and the lower piezoelectric gating layer 4, completing the redrawing of the three-dimensional force signal and even further completing the redrawing of the entire dynamic process;

[0064] The two together complete the reproduction of the high-precision three-dimensional force signals in the dynamic and non-dynamic processes, thus recording the tactile change information during the puncture process or enabling the robot to collect the tactile sense in real time during the puncture process, and further realizing the closed-loop control during the robot puncture process.

[0065] Such as Figure 9 shown, the present invention can be made into an arc suitable for the palm and pasted on the palm or palm-like mechanism for massage.

[0066] During the massage process, one side of the flexible tactile sensor contacts the object to be massaged, thus receiving the normal force and tangential force, and the other side is fixed to the palm. During this process, the normal force and tangential force are sequentially conducted through the flexible base layer made of the flexible non-conductive material PET, the piezoelectric gating layer, and then transmitted to the piezoelectric sensitive unit 5 made of the force-sensitive piezoelectric PVDF material with a lithographed spherical microstructure and a single-sided coating of conductive graphene and the piezoresistive sensitive unit 6 made of the force-sensitive piezoresistive PDMS material. Therefore, the force-sensitive piezoelectric PVDF material (i.e., the relatively arranged piezoelectric sensitive unit 5) and the force-sensitive piezoresistive PDMS material (i.e., the relatively arranged piezoresistive sensitive unit 6) respectively generate relative movement and extrusion;

[0067] During the process of changing the contact area of the PVDF material, the charges on both sides of the mutually contacting array piezoelectric PVDF materials change accordingly, and the signals generated during the dynamic process are transmitted to the external signal processing circuit through the upper piezoelectric gating layer 1 and the lower piezoelectric gating layer 4, completing the redrawing of the three-dimensional force signal and even further completing the redrawing of the entire dynamic process;

[0068] After the contact area of the PDMS material changes accordingly, the overall resistance of the mutually contacting array piezoresistive PDMS material changes accordingly, and the signals generated during the dynamic process are transmitted to the external signal processing circuit through the array gating upper piezoelectric gating layer 1 and the lower piezoelectric gating layer 4, completing the redrawing of the three-dimensional force signal and even further completing the redrawing of the entire dynamic process;

[0069] The two together complete the reproduction of the high-precision three-dimensional force signals in the dynamic and non-dynamic processes, thereby recording the tactile change information during the massage process or enabling the robot to achieve real-time acquisition of touch during the massage process, and further realizing the closed-loop control during the robot massage process.

[0070] Although the present invention has been described herein with reference to particular embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Accordingly, it should be understood that many modifications can be made to the exemplary embodiments and that other arrangements can be designed, provided that they do not depart from the spirit and scope of the invention as defined by the appended claims. It should be understood that the different dependent claims and the features described herein can be combined in a manner different from that described in the original claims. It should also be understood that the features described in connection with a single embodiment can be used in other described embodiments.

Claims

1. A flexible tactile sensor for a medical rehabilitation robot, characterized in that, it includes an upper piezoelectric gating layer (1), an upper force-sensitive layer (2), a lower force-sensitive layer (3), and a lower piezoelectric gating layer (4) arranged in sequence from top to bottom; The upper force-sensitive layer (2) and the lower force-sensitive layer (3) are arranged opposite to each other and in contact, and a conductive material is sprayed on their contact surfaces; both the upper force-sensitive layer (2) and the lower force-sensitive layer (3) are composed of an array formed by alternating arrangements between N columns of piezoelectric sensitive units (5) and N columns of piezoresistive sensitive units (6), and the N columns of piezoelectric sensitive units (5) of the upper force-sensitive layer (2) are arranged opposite to the N columns of piezoelectric sensitive units (5) of the lower force-sensitive layer (3), and the N columns of piezoresistive sensitive units (6) of the upper force-sensitive layer (2) are arranged opposite to the N columns of piezoresistive sensitive units (6) of the lower force-sensitive layer (3); N is an integer; All the piezoelectric sensitive units (5) and piezoresistive sensitive units (6) on the upper force-sensitive layer (2) are arranged on the gating nodes distributed in an array on the upper piezoelectric gating layer (1); all the piezoelectric sensitive units (5) and piezoresistive sensitive units (6) on the lower force-sensitive layer (3) are arranged on the gating nodes distributed in an array on the lower piezoelectric gating layer (4); Both the piezoelectric sensitive unit (5) and the piezoresistive sensitive unit (6) are composed of a closely arranged hemispherical array, and the hemispheres on the relatively arranged piezoelectric sensitive units (5) and the hemispheres on the relatively arranged piezoresistive sensitive units (6) are staggered from each other, so that when the hemispherical arrays on the relatively arranged piezoelectric sensitive units (5) and the hemispherical arrays on the relatively arranged piezoresistive sensitive units (6) are squeezed, they all form an interlock.

2. The flexible tactile sensor for a medical rehabilitation robot according to claim 1, characterized in that, it further includes two symmetrically arranged flexible base layers (7); The two flexible base layers (7) are respectively pasted on the upper surface of the upper piezoelectric gating layer (1) and the lower surface of the lower piezoelectric gating layer (4).

3. The flexible tactile sensor for a medical rehabilitation robot according to claim 2, characterized in that, The flexible base layer (7) is made of a non-conductive material PET material.

4. The flexible tactile sensor for a medical rehabilitation robot according to claim 1, characterized in that, The upper piezoelectric gating layer (1) is composed of a first gating circuit formed by spraying conductive silver paste on a non-conductive substrate; Each gating node in the first gating circuit is arranged in an array on the non-conductive substrate, and after being connected in series for each column of gating nodes, it is led out as a signal terminal of the upper piezoelectric gating layer (1).

5. The flexible tactile sensor for a medical rehabilitation robot according to claim 1, characterized in that, The lower piezoelectric gating layer (4) is composed of a second gating circuit formed by spraying conductive silver paste on a non-conductive substrate; The gating nodes in the second gating circuit are arranged in an array on a non-conductive substrate. The gating nodes with odd serial numbers in each row of gating nodes are connected simultaneously and led out as one signal terminal of the lower piezoelectric gating layer (4), and the gating nodes with even serial numbers are connected simultaneously and led out as the other signal terminal of the lower piezoelectric gating layer (4).

6. The flexible tactile sensor for a medical rehabilitation robot according to claim 1, characterized in that the conductive material sprayed on the hemispherical surfaces of the hemispherical arrays of the piezoelectric sensitive units (5) and the piezoresistive sensitive units (6) is graphene.

7. The flexible tactile sensor for a medical rehabilitation robot according to claim 1, characterized in that the piezoelectric sensitive unit (5) is made of PVDF material, and the piezoresistive sensitive unit (6) is made of PDMS material.

8. The flexible tactile sensor for a medical rehabilitation robot according to claim 1, characterized in that the piezoelectric sensitive unit (5) is formed by photolithography on the surface of a layer of PVDF material to form a closely arranged hemispherical array.

9. The flexible tactile sensor for a medical rehabilitation robot according to claim 1, characterized in that the piezoresistive sensitive unit (6) is formed by photolithography on the surface of a material made of PDMS to form a closely arranged hemispherical array.

10. The flexible tactile sensor for a medical rehabilitation robot according to claim 1, characterized in that the number of gating nodes on the upper piezoelectric gating layer (1) and the lower piezoelectric gating layer (4) is equal to the sum of the numbers of all the piezoelectric sensitive units (5) and all the piezoresistive sensitive units (6) on the upper force sensitive layer (2) or the lower force sensitive layer (3).

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