A method and device for in-situ self-sensing of friction of a magnetically sensitive rubber polymer

Abstract

The application discloses a kind of magnetic sensitive rubber polymer friction in-situ self-perception method and device, it is related to rubber friction sensing detection field, including magnetic sensitive rubber polymer friction self-perception principle and self-perception array design technology, three-dimensional force detection principle.The device includes loading drive module, electromagnetic control module, acquisition control module.The application has the ability of self-perception interface contact friction and the characteristics of magnetic field self-regulation friction, through the flexible array sensor in the inside of magnetic sensitive rubber, the normal stress and shear stress in the inside of magnetic sensitive rubber and the accurate position of stress point can be detected in real time, then beam-spring model is established to deduce stress-friction force relationship, the size and direction of magnetic sensitive rubber surface friction are calculated, so as to realize magnetic sensitive rubber interface friction in-situ self-perception.The method and device are effectively combined with computer system, can directly measure and regulate friction without the aid of external sensor, simple structure, in the rubber friction field has broad prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of rubber friction sensing detection, and relates to a friction self-sensing and self-regulating method and device based on a magnetic rubber polymer. BACKGROUND

[0002] In a modern industrial system, friction exists universally in mechanical equipment systems and nature, causing extremely high energy loss and inestimable loss to the national economy. With the continuous development and progress of automation technology and robot technology, magnetic control friction has become an important way for intelligent wear reduction and wear resistance of friction pairs. Traditional friction pairs are in a passive mechanical contact state during work, and it is difficult to realize online in-situ self-measurement of friction performance based on interface mechanics. The friction pairs are difficult to regulate and measure the friction performance and friction state during contact friction, which will inevitably cause friction and wear. Light wear will increase the material loss of the friction pair and energy consumption, and heavy wear will damage mechanical equipment and cause casualties.

[0003] Magnetic rubber is a new type of intelligent material with micrometer-sized magnetizable particles filled in a rubber-based matrix. The magnetic rubber can change its properties under the regulation of a magnetic field, thereby changing the friction performance. Although the magnetic rubber can realize magnetic control friction as a friction pair material, it cannot self-sense the internal stress, friction performance and friction force of the friction pair material, and needs to rely on other sensors to measure the above-mentioned performance. The external sensor not only increases the weight of the device, but also greatly increases the feedback delay. The current magnetic sensitive device research does not consider self-sensing measurement, cannot self-sense the piezoresistive / shear resistive performance of the magnetic sensitive device, and cannot combine the electrical characteristics and magnetic control friction characteristics.

[0004] At present, the real-time state, friction performance and friction force of the friction pair cannot be measured in-situ when the magnetic sensitive device is used as a friction pair, and only external sensors can be used. This has the problems of bloated measurement device and heavy weight, which restricts the application of the magnetic sensitive device. SUMMARY

[0005] Therefore, the purpose of the application is to provide a magnetic rubber polymer friction in-situ self-sensing method and device, and to combine the internal stress and magnetic control friction characteristics of the magnetic rubber. The surface friction force is calculated by measuring the internal stress change of the magnetic rubber and establishing a model, so as to realize in-situ measurement of the size and direction of the friction force of the friction pair.

[0006] To achieve the above purpose, the technical scheme adopted by the application comprises:

[0007] A magnetic sensitive rubber polymer comprises a magnetic sensitive rubber polymer matrix, a plurality of arrayed array sensor units and a flexible conductive film network; the array sensor unit comprises a lead electrode, an outer sensor unit sensitive layer, an inner sensor unit sensitive layer and a vertical sensor unit sensitive layer, the outer sensor unit sensitive layer and the inner sensor unit sensitive layer are annular structures, the vertical sensor unit sensitive layer, the inner sensor unit sensitive layer and the outer sensor unit sensitive layer are sequentially arranged from inside to outside, the lead electrode is connected to the outer sensor unit sensitive layer and the inner sensor unit sensitive layer and is connected to the electrode on the flexible conductive film network; the array sensor unit and the flexible conductive film network are inside the magnetic sensitive rubber polymer matrix, the array sensor unit is arrayed according to the electrode sequence of the flexible conductive film network at the bottom, and data transmission of each array sensor unit is ensured.

[0008] A preparation method of a magnetic sensitive rubber polymer comprises the following steps:

[0009] Step (1): preparing a single array sensor unit, using a modified iron nanowire polymer material to prepare an outer sensor unit sensitive layer, an inner sensor unit sensitive layer and a vertical sensor unit sensitive layer; the preparation method of the modified iron nanowire polymer material is as follows: an iron nanowire solution is added into a culture dish with a parallel magnetic field, after being immersed for a period of time, it is placed into a vacuum drying box for drying, and an iron nanowire sensitive material is obtained;

[0010] Then the obtained iron nanowire sensitive material is immersed in a carbon nanotube solution, after being immersed for a period of time, it is placed into a vacuum drying box for drying, and an iron nanowire / carbon nanotube sensitive material is obtained;

[0011] Finally, polyethylene terephthalate is used as a substrate material, the obtained iron nanowire / carbon nanotube sensitive material is coated and heated and dried to form an outer sensor unit sensitive layer, an inner sensor unit sensitive layer and a vertical sensor unit sensitive layer, and conductive nanomaterial is used as an electrode lead-out of the array sensor unit lead electrode;

[0012] Step (2): preparing an array sensor, m*n array sensor units in step (1) are prepared and arranged in a matrix, then each electrode is led out, a layer of flexible wire film network is placed at the bottom of all array sensor units, the wire film network is provided with an electrode interface corresponding to each sensor, and each electrode is led out to an external data acquisition card through the wire network and transmitted to an upper computer;

[0013] Step (3): preparing a magnetic sensitive rubber polymer: PDMS-A component and soft magnetic particles are mixed in a certain mass ratio and stirred clockwise uniformly, PDMS-B component is added and fully stirred, then it is placed into a vacuum drying box for vacuum bubble removal treatment, taken out and poured into a mold in which the array sensor prepared in advance is placed for solidification and molding, and the magnetic sensitive rubber and the array sensor are integrally molded by drying and heating.

[0014] A magnetic sensitive rubber polymer friction in-situ self-sensing device, comprising the magnetic sensitive rubber polymer, a base, an electromagnetic control device, a loading driving module, a signal acquisition module and a computer system; the magnetic sensitive rubber polymer is placed on the groove of the base, and the electromagnetic control device is fixed at the bottom of the magnetic sensitive rubber groove of the base to provide a magnetic field for the system;

[0015] The loading driving module comprises a sliding piece I, a sliding piece II, a sliding piece III, a support, a sliding guide rail I, a sliding guide rail II and a non-magnetic load block. Four supports are fixed on the base, four sliding pieces I are arranged on the four supports respectively, the sliding guide rail I is fixed at both ends of the sliding piece I respectively to form two parallel sliding rails, the sliding pieces III are arranged on the two sliding rails respectively, the sliding guide rail II is connected between the sliding pieces III, the sliding piece II is arranged on the sliding guide rail II, and the non-magnetic load block is fixed below the sliding piece II. A stepping motor drives the sliding piece I to drive the non-magnetic load block to move along the z-axis, a stepping motor drives the sliding piece III to drive the non-magnetic load block to move along the y-axis, and a stepping motor drives the sliding piece II to drive the non-magnetic load block to move along the x-axis.

[0016] One end of the signal acquisition module is connected with the magnetic sensitive rubber polymer, the other end is connected with the computer system, and the resistance value of the array sensor unit in the magnetic sensitive rubber polymer is acquired;

[0017] The computer system is used for receiving the data of the signal acquisition module, controlling the loading driving module and the electromagnetic control module to control the electric field, the magnetic field and the force.

[0018] A magnetic sensitive rubber polymer friction in-situ self-sensing method, comprising the following steps:

[0019] Step one: a target friction force to be reached by a magnetic sensitive rubber polymer surface is given, the normal stress, shear stress and time-varying information of the magnetic sensitive rubber polymer are set as state variables as pre-input data of a beam-spring model;

[0020] Step two: a non-magnetic load block is driven by a host computer control module to move at a constant speed along an arbitrary direction on the surface of the magnetic sensitive rubber polymer with a certain load;

[0021] Step three: the flexible array sensor inside the magnetic sensitive rubber polymer senses the stress change and the resistance value changes, the resistance value signal is acquired by a signal acquisition module and transmitted to the host computer, then a resistance value transformation matrix is output, and the force point position of the load block is determined according to the resistance value change of the row and column transformation;

[0022] Step four: after the force point position of the magnetic sensitive rubber polymer is obtained, the normal stress and shear stress of the point are directly measured by the sensor unit of the point, and then input into the beam-spring model of the host computer to obtain the friction force size and direction of the point.

[0023] Step five: compared with the target friction force input by the system, the electromagnetic control device adaptively adjusts the magnetic field size through the magnetic sensitive rubber polymer, thereby changing the surface friction of the magnetic sensitive rubber, until the measured friction force is equal to the target friction force, and the force point coordinates, magnetic field strength and friction force size and direction at this time are output.

[0024] The advantages and beneficial effects of the present application are:

[0025] 1. The friction in-situ self-sensing method and device of the magnetic sensitive rubber polymer disclosed in the present application can control the electric field, magnetic field, force, etc. through the computer upper machine control loading drive module and electromagnetic control module, and can realize in-situ testing and experimental exploration of the magnetic control friction force condition of the magnetic sensitive rubber under single variable condition through the test device.

[0026] 2. The friction in-situ self-sensing method and device of the magnetic sensitive rubber polymer disclosed in the present application can measure the real-time state and friction performance of the friction pair in-situ through the resistance signal generated during the contact friction process of the magnetic sensitive rubber and the friction pair, and has the advantages of low energy consumption, self-sensing and self-regulation.

[0027] 3. The friction in-situ self-sensing method and device of the magnetic sensitive rubber polymer disclosed in the present application adopts a resistance strain type array sensor based on iron nanowires as a self-sensing component to detect the contact friction state of the magnetic sensitive rubber-non-magnetic load block in-situ in real time. After the contact friction state is detected in real time by the upper machine control unit, the electromagnetic device is adaptively adjusted to realize in-situ sensing and regulation of the contact friction force state. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to make the purpose, technical scheme and advantages of the present application clearer, the preferred detailed description of the present application will be made below in combination with the drawings, in which:

[0029] Figure 1 The figure is a structure schematic diagram of the magnetic sensitive rubber polymer and the flexible array sensor structure of the present application;

[0030] Figure 2 The figure is a schematic diagram of the overall structure of the test bench of the present application;

[0031] Figure 3 The figure is a cross-sectional view of the magnetic sensitive rubber polymer of the present application;

[0032] Figure 4 The figure is a single sensing unit side force deformation and bridge circuit diagram of the present application;

[0033] Figure 5 The figure is a schematic diagram of a friction state micro-contact model of the present application;

[0034] Figure 6The wiring diagram of the 4*4 array sensor of the present application;

[0035] Figure 7 The manufacturing flow chart of the magnetic sensitive rubber and flexible array sensor integrated molding of the present application;

[0036] Figure 8 The flow chart of the in-situ self-sensing regulation of the magnetic sensitive rubber polymer friction of the present application;

[0037] The figure mark: 1-magnetic sensitive rubber polymer matrix, 2-wire electrode, 3-array sensor unit, 4-sensor unit outer sensitive layer, 5-sensor unit inner sensitive layer, 6-sensor unit vertical sensitive layer, 7-base, 8-electromagnetic regulation device, 9-magnetic sensitive rubber polymer, 10-sliding piece I, 11-sliding piece II, 12-sliding piece III, 13-strut, 14-sliding guide rail I, 15-sliding guide rail II, 16-non-magnetic load block, 17-flexible conductive film network. DETAILED DESCRIPTION

[0038] The following describes the embodiments of the present application through specific, concrete examples, and those skilled in the art can easily understand other advantages and effects of the present application from the disclosure of the present specification. The present application can also be implemented or applied through other different specific embodiments, and the details in the present specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the drawings provided in the following examples only illustrate the basic concept of the present application in a schematic manner, and the following examples and features in the examples can be combined with each other without conflict.

[0039] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "front", "back", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the terms describing the positional relationship in the drawings are only used for illustrative purposes, and cannot be understood as a limitation on the present application, for those skilled in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0040] Example 1:

[0041] As Figure 1As shown, a magnetic sensitive rubber polymer includes a magnetic sensitive rubber polymer base 1, a plurality of arrayed array sensor units 3, and a flexible conductive film network 17; the array sensor units 3 include lead electrodes 2, an outer sensitive layer 4 of the sensor unit, an inner sensitive layer 5 of the sensor unit, and a vertical sensitive layer 6 of the sensor unit, the outer sensitive layer 4 and the inner sensitive layer 5 of the sensor unit are annular structures, the vertical sensitive layer 6, the inner sensitive layer 5, and the outer sensitive layer 4 of the sensor unit are sequentially arranged from inside to outside, the lead electrodes 2 connect the outer sensitive layer 4 and the inner sensitive layer 5 of the sensor unit and are connected with electrodes on the flexible conductive film network 17; the array sensor units 3 and the flexible conductive film network 17 are inside the magnetic sensitive rubber polymer base 1, the array sensor units 3 are arrayed according to the electrode sequence of the flexible conductive film network 17 at the bottom, and data transmission of each array sensor unit 3 is ensured.

[0042] As shown in Figure 1 , the outer sensitive layer 4 and the inner sensitive layer 5 of the sensor unit form a rectangular double-layer structure, which is composed of four double-layer trapezoidal sensitive units R2, R3, R4, and R5 connected end to end to form a rectangle, and surrounds the inner circular vertical sensitive layer 6 of the sensor unit, leaving a gap in the middle. During production, magnetic sensitive rubber isolation is filled between the inner and outer sides to ensure that the crosstalk between the two is very small. The inner circular sensitive unit R1 is sensitive to normal strain but not sensitive to tangential strain, and senses the normal stress in the vertical direction. The outer rectangular sensitive unit is sensitive to tangential strain but not sensitive to normal strain, and senses the shear stress in the horizontal direction. Due to these characteristics, the crosstalk between the normal stress and the tangential stress is very small.

[0043] When the magnetic sensitive rubber polymer is subjected to normal and shear stress, the magnetic sensitive rubber polymer will undergo stress changes such as extrusion and shear. The flexible array sensor units inside the rubber will change the resistance value due to the change in stress. The position of the force point on the surface of the polymer can be determined through the row and column resistance value change matrix, and the sensor resistance value signal of this position is transmitted to the upper computer. The upper computer calculates the friction force at this time according to the resistance value, and then controls the electromagnetic control device to change the magnetic field size, thereby controlling the friction force on the surface of the magnetic sensitive rubber.

[0044] When the outer double-layer rectangular sensitive unit of the single flexible array sensor unit is subjected to tangential strain, the inner layer is extruded and the outer layer is stretched. The resistance area on one side is stretched, and the resistance area on the other side is compressed as shown in Figure 4 , the resistance of one side of the sensitive unit increases, and the resistance of the other side decreases, and the resistance change amount is amplified to make it more accurate; when the inner sensor unit is subjected to normal stress, the resistance value of the inner circular sensitive unit sensitive to the vertical direction will change, and the change amount of the resistance value can be measured to calculate the normal stress.

[0045] The outer side part of the single flexible array sensing unit is measured by two groups of units along the x-axis and y-axis shear stress, respectively, wherein R2 and R4 jointly measure the shear stress along the x-axis, R3 and R5 jointly measure the shear stress along the y-axis, and finally the friction along the x-axis and y-axis is calculated by a model, respectively, and the vector composition of the friction can obtain the size and direction of the friction to be solved.

[0046] The magnetic sensitive rubber polymer matrix 1, array sensing unit 3 and flexible conductive film network 17 adopt a layered embedding method to pour the magnetic sensitive rubber solution around the array sensing unit 3 and flexible conductive film network 17 prepared in advance, and then dry and integrally form.

[0047] The flexible sensor is made of sensitive materials such as iron nanowires and carbon nanotubes in a certain ratio by pouring into the normal and tangential mold respectively in batches; the flexible array sensing unit is evenly distributed in the magnetic sensitive rubber, and the electrodes of the flexible conductive film network at the bottom are arrayed in order to ensure the data transmission of each sensor; the 4*4 electrode arrangement output of the flexible conductive film network is as shown in Figure 6 .

[0048] The magnetic sensitive rubber has m*n array sensors evenly distributed in the magnetic sensitive rubber, and a layer of flexible conductive film 17 with conductive circuit network is placed at the bottom of the entire array sensor to ensure the resistance value data transmission of the sensor, as shown in Figure 3 .

[0049] Example 2

[0050] As shown in Figure 7 , a preparation method of a magnetic sensitive rubber polymer comprises the following steps:

[0051] Step 1: preparing a single array sensing unit, using modified iron nanowire polymer material to prepare the outer sensitive layer, inner sensitive layer and vertical sensitive layer of the sensing unit; the preparation method of the modified iron nanowire polymer material is to immerse the iron nanowire solution in a culture dish with a parallel magnetic field, immerse for a period of time, and then dry in a vacuum drying box to obtain an iron nanowire sensitive material;

[0052] Then immerse the obtained iron nanowire sensitive material in a carbon nanotube solution, immerse for a period of time, and then dry in a vacuum drying box to obtain an iron nanowire / carbon nanotube sensitive material;

[0053] Finally, using polyethylene terephthalate as a substrate material, the obtained iron nanowire / carbon nanotube sensitive material is coated and heated and dried to form the outer sensitive layer, inner sensitive layer and vertical sensitive layer of the sensing unit, and conductive nanomaterial is used as the electrode lead electrode of the array sensing unit;

[0054] Step 2: Prepare the array sensor, prepare m*n array sensor units in step 1 and arrange them in a matrix, then lead out each electrode, place a layer of flexible wire film network at the bottom of all array sensor units, and arrange electrode interfaces corresponding to each sensor on the wire film network, and each electrode is led out to the external data acquisition card through the wire network and transmitted to the upper computer;

[0055] Step 3: Prepare the magnetic sensitive rubber polymer: mix PDMS-A component and soft magnetic particles in a certain mass ratio and stir clockwise until uniform, add PDMS-B component and stir thoroughly, then put it into a vacuum drying box for vacuum bubble removal treatment, take it out and pour it into the mold of the array sensor prepared in advance for solidification and molding, and the magnetic sensitive rubber and the array sensor are integrally formed by drying and heating. The mass ratio of PDMS A:PDMS B is 15:1, and the volume fraction of soft magnetic particles is 10%.

[0056] The soft magnetic particles are multiple or one of carbonyl iron powder, carbonyl nickel powder and carbonyl cobalt powder, which are used to enhance the magnetic control friction performance. In this embodiment, carbonyl iron powder is used.

[0057] The conductive nanomaterial is one or more of conductive silver wire, conductive copper wire and conductive carbon wire.

[0058] The iron nanowire polymer material has excellent magnetic control friction performance and piezoresistive characteristics after modification, and can change its resistance value according to the stress condition.

[0059] Example three:

[0060] As shown in Figure 2 A friction in-situ self-sensing device of a magnetic sensitive rubber polymer, comprising a magnetic sensitive rubber polymer 9, a base 7, an electromagnetic control device 8, a loading driving module, a signal acquisition module and a computer system; the magnetic sensitive rubber polymer 9 is placed on the groove of the base 7, and the electromagnetic control device 8 is fixed at the bottom of the magnetic sensitive rubber groove of the base 7 to provide a magnetic field for the system.

[0061] The loading drive module includes a stepping motor, sliding member I 10, sliding member II 11, sliding member III 12, a support 13, sliding guide rail I 14, sliding guide rail II 15 and a non-magnetic load block 16; four supports 13 are fixed on the base 7, four sliding members I 10 are arranged on the four supports 13 respectively, the sliding guide rail I 14 is fixed at both ends of the sliding member I 10 respectively, forming two parallel sliding rails, the sliding member III 12 is arranged on the two sliding rails respectively, the sliding member III 12 is connected through the sliding guide rail II 15, the sliding member II 11 is arranged on the sliding guide rail II 15, the non-magnetic load block 16 is fixed below the sliding member II 11, the stepping motor drives the sliding member I 10 to drive the non-magnetic load block 16 to move along the z-axis, the stepping motor drives the sliding member III 12 to drive the non-magnetic load block 16 to move along the y-axis, and the stepping motor drives the sliding member II 11 to drive the non-magnetic load block 16 to move along the x-axis.

[0062] The signal acquisition module is connected with the magnetic sensitive rubber polymer 9 at one end and connected with the computer system at the other end. When the magnetic sensitive rubber polymer is in contact with the non-magnetic load block and is extruded or sheared, the resistance value of the array sensor unit in the magnetic sensitive rubber polymer changes according to the friction force condition and is transmitted to the data acquisition card.

[0063] The non-magnetic load block 16 is located directly above the magnetic sensitive rubber polymer 9 to be measured and includes a load block and a connecting rod, both of which are made of a non-magnetic material, and the transmission mode is gear belt transmission.

[0064] The motor stepping motor is placed in the sliding member to ensure that the device is not disturbed by the magnetic field during operation.

[0065] According to the information sent by the upper computer, the electromagnetic control device adjusts the magnetic field to adjust the contact friction force between the non-magnetic load block and the magnetic sensitive rubber friction pair. The m*n sensor units are arranged in an array distribution form in the magnetic sensitive rubber polymer and are integrally formed, and the contact surface is divided into m*n row and column contact areas according to the positions of the sensors, and the friction force parameters of the contact area corresponding to each sensor are accurately measured.

[0066] The array sensor unit can measure the contact friction state of the magnetic sensitive rubber and the load block in real time, and transmit the sensing signal to the data acquisition card through a flexible conductive film network as shown in Figure 6 The flexible film conductive network electrode is connected with each array sensor unit and outputs a signal through a bus.

[0067] The electromagnetic control module 8 is fixed at the bottom of the magnetic sensitive rubber groove of the base 7, and provides a magnetic field for the system. The driving device and the electromagnetic control device are mainly used to realize the friction force condition between the magnetic sensitive rubber and the non-magnetic load block under different magnetic fields.

[0068] The driving device drives the contact friction between the carrier block and the magnetic sensitive rubber, so that the deformation occurs inside the magnetic sensitive rubber. The normal stress and the tangential stress generated by the normal strain and the tangential strain caused by the contact friction are measured by the piezoresistive sensor embedded in the magnetic sensitive rubber. Then, the relationship between the stress and the friction force is established by the beam-spring model, and the real-time friction force is calculated by the upper computer.

[0069] Embodiment four:

[0070] As Figure 8 shown, a magnetic sensitive rubber polymer friction in-situ self-sensing method includes the following steps:

[0071] Step one: given a magnetic sensitive rubber polymer surface needs to achieve the target friction, the normal stress, shear stress and its time-varying information of the magnetic sensitive rubber polymer are set as state variables, which are used as the pre-input data of the beam-spring model;

[0072] Step two: the upper computer control module drives the non-magnetic carrier block to move at a constant speed along any direction on the surface of the magnetic sensitive rubber polymer with a certain load;

[0073] Step three: the flexible array sensor inside the magnetic sensitive rubber polymer senses the stress change and its resistance value changes. The resistance value signal is collected by the signal acquisition module and transmitted to the upper computer, and then a resistance value transformation matrix is output. The force point position of the carrier block is determined according to the resistance value change of row and column transformation;

[0074] Step four: after obtaining the force point position of the magnetic sensitive rubber polymer, the normal stress and shear stress of the point are measured directly through the sensing unit of the point, and then input into the beam-spring model of the upper computer to obtain the friction force size and direction of the point;

[0075] Step five: compared with the target friction force input by the system, the electromagnetic control device adjusts the magnetic field size through the magnetic sensitive rubber polymer, and then changes the surface friction of the magnetic sensitive rubber, until the measured friction force is equal to the target friction force, and the force point coordinates, magnetic field intensity and friction force size and direction at this time are output.

[0076] Through a large number of experiments in the early stage and simulation analysis and theoretical derivation in the later stage, the relationship between friction force and resistance value change in the magnetic field environment is decoupled. Through the measurement of resistance signal, the real-time magnetic control friction force of magnetic sensitive rubber and non-magnetic carrier block, real-time friction factor and other friction characteristics can be measured and calculated in-situ.

[0077] The magnetic sensitive rubber polymer surface is divided into areas according to the distributed nodes of the flexible array sensor. When a node is subjected to an external force, the resistance of the sensors around the node changes. The node area of the maximum force point can be determined through the resistance change matrix between the rows and columns. Then, according to the node area, one or more matrix sensors around the node are matched, and the resistance signal collected is transmitted to the upper computer. The upper computer processes the stress change corresponding to the resistance value measured by the sensor to calculate the friction force. The resistance collection system of the matrix sensor can automatically match the 1*1, 2*2, 3*3… matrix resistance values at the position according to the force area of the magnetic sensitive rubber surface to calculate.

[0078] The beam-spring model is equivalent to a beam-spring model connected by a cantilever beam and a spring according to the various peaks such as Figure 5 as shown in the microstructure, and the model is theoretically derived as follows:

[0079] The mechanical analysis of the i-th micro beam-spring model along the x-axis direction can obtain the following relationship:

[0080]

[0081] is the friction force received by the i-th micro beam-spring model in the x-axis direction;

[0082] is the beam bending force received by the i-th micro beam-spring model in the x-axis direction;

[0083] is the elastic force received by the i-th micro beam-spring model in the x-axis direction.

[0084] Then, the forces of all micro beams are combined to obtain the following formula:

[0085] F fx = F ex +F bx

[0086] F fx is the total friction force received by the contact area in the x-axis direction, F ex is the total beam bending force received by the contact area in the x-axis direction, F bx is the total elastic force received by the contact area in the x-axis direction.

[0087] Using the Euler-Bernoulli beam theory, the deflection of the cantilever beam under the bending force f bx is:

[0088]

[0089] δ x Let be the tip bending amount of the i-th beam along the x-axis, h be the distance from the center line of the sensor unit to the upper surface, and z be the z-axis coordinate value;

[0090] Then τ is calculated. x With F bx Relationship:

[0091] in

[0092] τ x Let G be the shear stress along the x-axis, and h be the shear modulus. r The value is a point between 0 and h;

[0093] F is obtained using empirical methods. ex With σ z The relationship between them: The coefficient k x and m x It was obtained through extensive preliminary experimental calibration. x m x These are the experimental coefficients, determined through repeated trials and calibration, σ z The stress along the z-axis—that is, the normal stress—is the stress when the sensor is at the critical point where it is about to begin sliding. ex When in a saturated state, we mean Then it is known We get Given the critical normal stress, we finally conclude that:

[0094] (where τ) x With σ z (obtained directly from the sensor)

[0095] This represents the bending force of the saturated beam at the critical slip point. After obtaining the frictional force along the x-axis, the frictional force along the y-axis can be obtained similarly using the same method. Finally, vector synthesis yields the magnitude and direction of the total frictional force.

[0096]

[0097] F fy This represents the total frictional force experienced by the contact area in the y-axis direction.

[0098] The working principle of the application is as follows: the application fully utilizes the characteristics of the magnetic sensitive rubber that can change the surface morphology and the surface friction under the regulation of the magnetic field, embeds the array sensing unit into the magnetic sensitive rubber polymer, and realizes the integration of sensing and control. Under the action of the external magnetic field, the friction regulation process of the magnetic sensitive rubber polymer is as follows: initially, a target friction force to be reached is set in advance, then a load moving at a uniform speed in any direction is applied to the surface of the magnetic sensitive rubber polymer through the loading driving device, the array sensing unit senses the stress change information in the magnetic sensitive rubber polymer at this time and transmits it to the upper computer, the upper computer deduces the friction force size and direction at this time through the pre-established stress-friction force model, then the upper computer controls the electromagnetic device to change the magnetic field strength through the magnetic sensitive rubber, changes the surface friction of the magnetic sensitive rubber, the array sensing unit continuously senses the friction force, until the pre-set friction force is reached, and the stress point coordinates, the magnetic field strength and the friction force size and direction at this time are output.

[0099] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the application and not to limit it, although the application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the application can be modified or replaced equivalently without departing from the purpose and scope of the technical solutions, and they should be covered in the scope of the claims of the application.

Claims

1. A magnetically sensitive rubber polymer, characterized in that: The system includes a magnetically sensitive rubber polymer matrix (1), several arrayed flexible array sensing units (3), and a flexible conductive thin film network (17). Each flexible array sensing unit (3) includes a lead electrode (2), an outer sensing layer (4), an inner sensing layer (5), and a vertical sensing layer (6). The outer sensing layer (4) and the inner sensing layer (5) are ring-shaped. The vertical sensing layer (6), the inner sensing layer (5), and the outer sensing layer (4) are arranged sequentially from the inside out. The lead electrode (2) connects to the outer sensing layer (6). 4) The sensing unit is connected to the sensitive layer (5) and the electrodes on the flexible conductive thin film network (17); the flexible array sensing unit (3) and the flexible conductive thin film network (17) are inside the magnetically sensitive rubber polymer matrix (1), and the flexible array sensing unit (3) is arranged in an array according to the electrode sequence of the bottom flexible conductive thin film network (17) to ensure data transmission of each flexible array sensing unit (3); the vertical sensitive layer (6) of the sensing unit is used to sense the normal stress in the vertical direction; the outer sensitive layer (4) and the inner sensitive layer (5) of the sensing unit are used to sense the shear stress in the horizontal direction; The flexible array sensing unit (3) changes its resistance value according to the change in stress.

2. The magnetically sensitive rubber polymer according to claim 1, characterized in that: The outer sensitive layer (4) and the inner sensitive layer (5) of the sensing unit form a rectangular double-layer structure. Four double-layer trapezoidal sensitive units are connected end to end to form a rectangle, which surrounds the inner circular vertical sensitive layer (6) of the sensing unit. The inner and outer sides are filled with magnetic rubber for isolation.

3. The magnetically sensitive rubber polymer according to claim 1 or 2, characterized in that: The magnetic sensitive rubber polymer matrix (1), flexible array sensing unit (3) and flexible conductive thin film network (17) are integrally formed by injecting magnetic sensitive rubber solution around the pre-prepared flexible array sensing unit (3) and flexible conductive thin film network (17) in a layered embedding manner and then drying.

4. A friction in-situ self-sensing device for magnetically sensitive rubber polymers, characterized in that: The system includes the magnetically sensitive rubber polymer (9) as described in any one of claims 1-3, a base (7), an electromagnetic control device (8), a loading drive module, a signal acquisition module, and a computer system; the magnetically sensitive rubber polymer (9) is placed on the groove of the base (7), and the electromagnetic control device (8) is fixed to the bottom of the magnetically sensitive rubber groove of the base (7) to provide a magnetic field for the magnetically sensitive rubber polymer (9); The loading drive module includes slider I (10), slider II (11), slider III (12), support column (13), sliding guide rail I (14), sliding guide rail II (15), and non-magnetic carrier block (16); the four support columns (13) are fixed on the base (7), the four sliders I (10) are respectively set on the four support columns (13), and the sliders I (10) are fixed at both ends of the sliding guide rail I (14) to form two parallel slide rails, and sliders III are respectively set on the two slide rails. (12) The sliding parts Ⅲ (12) are connected by the sliding guide rail Ⅱ (15). The sliding guide rail Ⅱ (15) is provided with the sliding part Ⅱ (11). The non-magnetic block (16) is fixed below the sliding part Ⅱ (11). The stepper motor drives the sliding part Ⅰ (10) to move the non-magnetic block (16) along the z-axis. The stepper motor drives the sliding part Ⅲ (12) to move the non-magnetic block (16) along the y-axis. The stepper motor drives the sliding part Ⅱ (11) to move the non-magnetic block (16) along the x-axis. One end of the signal acquisition module is connected to the magnetic rubber polymer (9), and the other end is connected to the computer system to acquire the resistance value of the flexible array sensing unit in the magnetic rubber polymer.

5. The in-situ self-sensing device for friction of a magnetically sensitive rubber polymer according to claim 4, characterized in that: The stepper motor is placed in the sliding component to ensure that the device is not affected by magnetic field interference during operation.

6. The in-situ self-sensing device for friction of a magnetically sensitive rubber polymer according to claim 4, characterized in that: The non-magnetic carrier block (16) is located directly above the magnetically sensitive rubber polymer (9) to be tested and is made of non-magnetic material.

7. A method for in-situ self-sensing of friction in a magnetically sensitive rubber polymer based on the device described in any one of claims 4-6, characterized in that, Includes the following steps: Step 1: Given a target frictional force that the surface of a magnetically sensitive rubber polymer needs to achieve, set the normal and shear stresses and their time-varying information on the magnetically sensitive rubber polymer as state variables, and use them as pre-input data for the beam-spring model; Step 2: The computer system control module drives the non-magnetic carrier block to move at a constant speed in any direction on the surface of the magnetically sensitive rubber polymer with a certain load; Step 3: The flexible array sensing unit inside the magnetic rubber polymer senses the stress change and its resistance value changes. The resistance value signal is collected by the signal acquisition module and transmitted to the computer system. Then, a resistance value transformation matrix is ​​output. The position of the force point of the loading block is determined according to the resistance value change of the row and column transformation. Step 4: After obtaining the location of the stress point of the magnetically sensitive rubber polymer, directly measure the normal stress and shear stress through the sensing unit at that point, and then input them into the beam-spring model of the computer system to obtain the magnitude and direction of the friction force at that point. The beam-spring model is as follows: F fx F is the total frictional force experienced by the contact area in the x-axis direction. ex F is the total beam bending force experienced by the contact area in the x-axis direction. bx This represents the total elastic force experienced by the contact area in the x-axis direction. This represents the saturated beam bending force at the critical slip condition. After obtaining the frictional force along the x-axis, the frictional force along the y-axis can be obtained similarly using the same method. Finally, the vector summation yields the magnitude and direction of the total frictional force. F fy This represents the total frictional force experienced by the contact area in the y-axis direction. Step 5: Compare the measured friction force with the target friction force input by the computer system. The electromagnetic control device adaptively adjusts the magnitude of the magnetic field passing through the magnetic rubber polymer, thereby changing the surface friction force of the magnetic rubber until the measured friction force is equal to the target friction force. The coordinates of the force point, the magnetic field strength, and the magnitude and direction of the friction force are then output.

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