Friction in-situ self-sensing method and device for magnetic-sensitive rubber polymer

Abstract

The invention discloses a friction in-situ self-sensing method and a friction in-situ self-sensing device for a magnetic-sensitive rubber polymer, relates to the field of rubber friction sensing detection, and comprises a magnetic-sensitive rubber polymer friction self-sensing principle, a self-sensing array design technology and a three-dimensional force detection principle. The device comprises a loading driving module, an electromagnetic regulation and control module and an acquisition control module. The device has the capability of autonomously sensing interface contact friction and the characteristic of autonomously regulating and controlling friction by a magnetic field, normal stress and shear stress in the magnetic-sensitive rubber and the accurate position of a stress point can be detected in real time through the flexible array sensor in the magnetic-sensitive rubber, and then a beam-spring model is established to deduce a stress-friction force relationship; and calculating the magnitude and direction of the surface friction force of the magnetic-sensitive rubber so as to realize in-situ self-sensing of the interface friction of the magnetic-sensitive rubber. The method and the device are effectively combined with a computer system, friction force can be directly measured and regulated without the help of an external sensor, the structure is simple, and the method and the device have wide prospects in the field of rubber friction.

Description

Technical Field

[0001] The invention belongs to the field of rubber friction sensing detection, and relates to a friction self-sensing and self-regulating method and device based on magnetically sensitive rubber polymer. Background Art

[0002] In the modern industrial system, friction is ubiquitous in mechanical equipment systems and nature, causing extremely high energy losses and inestimable losses to the national economy. With the continuous development and progress of automation technology and robotics technology, magnetically controlled friction has become an important way to reduce wear and resist wear in friction pairs. Traditional friction pairs are in a passive mechanical contact state during operation, and it is difficult to achieve friction performance regulation based on online in-situ autonomous measurement of interface mechanics. It is difficult for friction pairs to regulate and measure the friction performance and friction state during the contact friction process, which will inevitably cause friction and wear. At the least, it will increase the material loss and energy consumption of the friction pair, and at worst, it will damage mechanical equipment and cause casualties.

[0003] Magnetic sensitive rubber is a new type of intelligent material with rubber as the main body and can be filled with micron-sized magnetizable particles. Magnetic sensitive rubber can change its own properties under the control of a magnetic field, thereby achieving a change in friction performance. Although magnetic sensitive rubber can be used as a friction pair material to achieve magnetically controlled friction of the friction pair, it cannot self-sense the internal stress, friction performance, friction force, etc. of the friction pair material, and requires additional sensors to measure the above performance. External sensors not only increase the load of the device, but also greatly increase the feedback delay. Current research on magnetic sensitive devices does not consider self-sensing measurement, and cannot self-sensingly measure the piezoresistance / shear resistance performance of magnetic sensitive devices, and cannot combine electrical properties with magnetically controlled friction properties.

[0004] At present, when magnetic sensitive devices are used as friction pairs, the real-time status, friction performance and friction force of the friction pairs cannot be measured in situ. They can only be measured with the help of external sensors, and the measurement equipment is bloated and heavy, which restricts the application of magnetic sensitive devices. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a method and device for in-situ self-sensing friction of a magnetically sensitive rubber polymer, and to provide a method and device that can combine the internal stress of the magnetically sensitive rubber with the magnetically controlled friction characteristics, measure the changes in the internal stress of the magnetically sensitive rubber, and then derive and calculate its surface friction by establishing a model, thereby realizing in-situ measurement of the magnitude and direction of the friction force of the friction pair.

[0006] In order to achieve the above object, the technical solution adopted by the present invention includes:

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

[0008] A method for preparing a magnetically 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 sensitive layer of the sensor unit, an inner sensitive layer of the sensor unit and a vertical sensitive layer of the sensor unit; the preparation method of the modified iron nanowire polymer material is to add an iron nanowire solution into a culture dish with a parallel magnetic field applied, immerse for a period of time, and then put it into a vacuum drying oven to dry, so as to obtain an iron nanowire sensitive material;

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

[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 a sensing unit outer sensitive layer, a sensing unit inner sensitive layer and a sensing unit vertical sensitive layer, and a conductive nanomaterial is used as an electrode lead-out of the sensing array sensing unit lead electrode;

[0012] Step (2): preparing an array sensor, preparing m*n array sensor units in step (1) and arranging them in a matrix, then leading out each electrode, placing a layer of flexible wire film network at the bottom of all array sensor units, the wire film network is arranged with an electrode interface corresponding to each sensor, and each electrode is led out to an external data acquisition card through the wire network for transmission to a host computer;

[0013] Step (3): Preparation of magnetically sensitive rubber polymer: PDMS-A component and soft magnetic particles are mixed in a certain mass ratio and stirred evenly in a clockwise direction, PDMS-B component is added and stirred sufficiently, and then placed in a vacuum drying oven for vacuum extraction of bubbles, and then taken out and poured into a mold of an array sensor prepared in advance for curing and forming, and the magnetically sensitive rubber and the array sensor are dried and heated to form an integral unit.

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

[0015] The loading drive module includes a sliding member I, a sliding member II, a sliding member III, a pillar, a sliding guide rail I, a sliding guide rail II and a non-magnetic conductive carrier block; four of the pillars are fixed on the base, and four sliding members I are respectively arranged on the four pillars. Sliding members I are respectively fixed at both ends of the sliding guide rail I to form two parallel sliding rails, and sliding members III are respectively arranged on the two sliding rails. The sliding members III are connected by the sliding guide rail II, and the sliding member II is arranged on the sliding guide rail II. The non-magnetic conductive carrier block is fixed below the sliding member II. The stepper motor drives the sliding member I to drive the non-magnetic conductive carrier block to move along the z-axis, the stepper motor drives the sliding member III to drive the non-magnetic conductive carrier block to move along the y-axis, and the stepper motor drives the sliding member II to drive the non-magnetic conductive carrier block to move along the x-axis;

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

[0017] The computer system is used to receive data from the signal acquisition module, control the loading drive module and the electromagnetic control module, and thus control the electric field, magnetic field, and force.

[0018] A method for in-situ self-sensing friction of a magnetically sensitive rubber polymer comprises the following steps:

[0019] Step 1: Given a target friction force that needs to be achieved on a magnetically sensitive rubber polymer surface, the normal and shear stresses and their time-varying information of the magnetically sensitive rubber polymer are set as state variables as pre-input data for the beam-spring model;

[0020] Step 2: The host computer control module drives the non-magnetic conductive carrier block to move at a constant speed in any direction with a certain load on the surface of the magnetic sensitive rubber polymer;

[0021] Step 3: The flexible array sensor inside the magnetically 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 host computer, and 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;

[0022] Step 4: After obtaining the position of the force point of the magnetically sensitive rubber polymer, the normal stress and shear stress are directly measured through the sensing unit at the point, and then input into the beam-spring model of the host computer to obtain the magnitude and direction of the friction force at the point;

[0023] Step 5: By comparing with the target friction force input by the system, the electromagnetic control device adaptively adjusts the size of the magnetic field passing through the magnetically sensitive rubber polymer, thereby changing the surface friction of the magnetically sensitive rubber until the measured friction force is equal to the target friction force, and outputs the coordinates of the force point, magnetic field strength, and friction force size and direction at this time.

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

[0025] 1. The in-situ self-sensing method and device for friction of magnetically sensitive rubber polymer disclosed in the present invention can control the electric field, magnetic field, force, etc. by loading the drive module and the electromagnetic control module through a computer host computer. The test device can be used to realize in-situ testing and experimental exploration of the magnetic controlled friction force condition of magnetically sensitive rubber under a single variable condition.

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

[0027] 3. The in-situ self-sensing method and device for friction of magnetic sensitive rubber polymer disclosed in the present invention adopts a resistive strain array sensor based on iron nanowires as a self-sensing component to perform online in-situ real-time detection of the contact friction state of magnetic sensitive rubber-non-magnetic carrier block. After the contact friction state is detected in real time by the host computer control unit, the electromagnetic device is adaptively adjusted to achieve in-situ sensing and regulation of the contact friction state. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0029] Figure 1 It is a schematic diagram of the structure of the magnetically sensitive rubber polymer and the flexible array sensor thereof of the present invention;

[0030] Figure 2 It is a schematic diagram of the overall structure of the test bench of the present invention;

[0031] Figure 3 is a cross-sectional view of the magnetically sensitive rubber polymer of the present invention;

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

[0033] Figure 5 It is a schematic diagram of the friction state micro-contact model of the present invention;

[0034] Figure 6This is the wiring diagram of the 4*4 array sensor of the present invention;

[0035] Figure 7 This is a flowchart of the integrated molding of the magnetic sensitive rubber and the flexible array sensor of the present invention;

[0036] Figure 8 This is a flow chart of the in-situ self-sensing control of friction of the magnetically sensitive rubber polymer of the present invention;

[0037] Figure numerals: 1-magnetically sensitive rubber polymer matrix, 2-lead electrode, 3-array sensing unit, 4-sensing unit outer sensitive layer, 5-sensing unit inner sensitive layer, 6-sensing unit vertical sensitive layer, 7-base, 8-electromagnetic control device, 9-magnetically sensitive rubber polymer, 10-sliding member I, 11-sliding member II, 12-sliding member III, 13-pillar, 14-sliding guide rail I, 15-sliding guide rail II, 16-non-magnetic carrier block, 17-flexible conductive film network. DETAILED DESCRIPTION

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

[0039] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0040] Embodiment 1:

[0041] like Figure 1As shown, a magnetically sensitive rubber polymer comprises a magnetically sensitive rubber polymer matrix 1, a plurality of arrayed array sensing units 3 and a flexible conductive film network 17; the array sensing unit 3 comprises a lead electrode 2, a sensing unit outer sensitive layer 4, a sensing unit inner sensitive layer 5 and a sensing unit vertical sensitive layer 6, the sensing unit outer sensitive layer 4 and the sensing unit inner sensitive layer 5 are annular structures, the sensing unit vertical sensitive layer 6, the sensing unit inner sensitive layer 5 and the sensing unit outer sensitive layer 4 are arranged in sequence from inside to outside, the lead electrode 2 connects the sensing unit outer sensitive layer 4 and the sensing unit inner sensitive layer 5 and is connected to the electrodes on the flexible conductive film network 17; the array sensing units 3 and the flexible conductive film network 17 are inside the magnetically sensitive rubber polymer matrix 1, the array sensing units 3 are arranged in an array according to the electrode sequence of the flexible conductive film network 17 at the bottom, so as to ensure data transmission of each array sensing unit 3.

[0042] like Figure 1 As shown, the outer sensitive layer 4 of the sensing unit and the inner sensitive layer 5 of the sensing 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, which surrounds the inner circular vertical sensitive layer 6 of the sensing unit, leaving a gap in the middle. During the manufacturing process, magnetic sensitive rubber 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 to tangential strain, and senses the normal stress in the vertical direction. The outer rectangular sensitive unit is sensitive to tangential strain but not to normal strain, and senses the shear stress in the horizontal direction. Due to these characteristics, the crosstalk between normal stress and tangential stress is very small.

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

[0044] When the outer double-layer rectangular sensitive unit of the single flexible array sensing unit is subjected to tangential strain, the inner layer is squeezed 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 FIG. Figure 4 As shown, the resistance of one side of the sensitive unit increases, while the resistance of the other side decreases, and the resistance change is amplified to make it more accurate; when the inner sensing 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 in its resistance value can be measured to calculate the normal stress.

[0045] The outer part of the single flexible array sensing unit is composed of two groups of units that measure the shear stress along the x-axis and the y-axis respectively, among which R2 and R4 jointly measure the shear stress along the x-axis, and R3 and R5 jointly measure the shear stress along the y-axis. Finally, the friction forces along the x-axis and the y-axis are calculated respectively through the model, and their vector synthesis can obtain the magnitude and direction of the friction force to be calculated.

[0046] The magnetically sensitive rubber polymer matrix 1, the array sensing unit 3 and the flexible conductive film network 17 are formed in one piece by layered embedding, wherein the magnetically sensitive rubber solution is poured around the pre-prepared array sensing unit 3 and the flexible conductive film network 17 and then dried.

[0047] Flexible sensors are made of sensitive materials such as iron nanowires and carbon nanotubes in a certain ratio and poured into normal and tangential molds in batches; the flexible array sensor unit consists of m*n sensors evenly distributed inside the magnetic sensitive rubber, arranged in an array according to the electrode sequence of the flexible conductive film network at the bottom to ensure data transmission of each sensor; the 4*4 electrode arrangement output of the flexible conductive film network is as follows Figure 6 shown.

[0048] There are m*n array sensors evenly distributed inside the magnetic sensitive rubber. A layer of flexible conductive film 17 with a conductive line network is placed at the bottom of the entire array sensor to ensure the transmission of the sensor resistance value data. Figure 3 shown.

[0049] Embodiment 2:

[0050] like Figure 7 As shown, a method for preparing a magnetically sensitive rubber polymer comprises the following steps:

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

[0052] Then the obtained iron nanowire sensitive material is immersed in the carbon nanotube solution, and after being immersed for a period of time, it is placed in a vacuum drying oven for drying to obtain the iron nanowire / carbon nanotube sensitive material;

[0053] 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 a sensing unit outer sensitive layer, a sensing unit inner sensitive layer and a sensing unit vertical sensitive layer, and a conductive nanomaterial is used as an electrode lead-out of the sensing array sensing unit lead electrode;

[0054] Step 2: Prepare an 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. The wire film network is provided with electrode interfaces corresponding to each sensor. Each electrode is led out to an external data acquisition card through the wire network and transmitted to a host computer.

[0055] Step 3: Prepare magnetic sensitive rubber polymer: Mix PDMS-A component and soft magnetic particles in a certain mass ratio and stir them clockwise, add PDMS-B component and stir them thoroughly, put them into a vacuum drying oven for vacuum extraction of bubbles, take them out and pour them into the mold of the array sensor prepared in advance for curing and forming, and the magnetic sensitive rubber and the array sensor are dried and heated to form an integrated whole. The mass ratio of PDMS A:PDMS B is 15:1, and the volume fraction of soft magnetic particles accounts for 10%.

[0056] The soft magnetic particles are one or more of carbonyl iron powder, carbonyl nickel powder and carbonyl cobalt powder, and 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 magnetically controlled friction performance and piezoresistive properties after modification, and can change its own resistance value according to the stress conditions.

[0059] Embodiment three:

[0060] like Figure 2 As shown, a friction in-situ self-sensing device of a magnetically sensitive rubber polymer comprises a magnetically sensitive rubber polymer 9, 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 system;

[0061] The loading drive module includes a stepper motor, a sliding member Ⅰ10, a sliding member Ⅱ11, a sliding member Ⅲ12, a pillar 13, a sliding guide rail Ⅰ14, a sliding guide rail Ⅱ15 and a non-magnetic conductive carrier block 16; the four pillars 13 are fixed on the base 7, the four sliding members Ⅰ10 are respectively arranged on the four pillars 13, the sliding members Ⅰ10 are respectively fixed at both ends of the sliding guide rail Ⅰ14 to form two parallel sliding rails, the sliding members Ⅲ12 are respectively arranged on the two sliding rails, the sliding members Ⅲ12 are connected by the sliding guide rail Ⅱ15, the sliding member Ⅱ11 is arranged on the sliding guide rail Ⅱ15, the non-magnetic conductive carrier block 16 is fixed below the sliding member Ⅱ11, the stepper motor drives the sliding member Ⅰ10 to drive the non-magnetic conductive carrier block 16 to move along the z-axis, the stepper motor drives the sliding member Ⅲ12 to drive the non-magnetic conductive carrier block 16 to move along the y-axis, and the stepper motor drives the sliding member Ⅱ11 to drive the non-magnetic conductive carrier block 16 to move along the x-axis.

[0062] One end of the signal acquisition module is connected to the magnetically sensitive rubber polymer 9, and the other end is connected to the computer system. When the magnetically sensitive rubber polymer contacts the non-magnetic loading block and is squeezed or sheared, the resistance value of the array sensor unit in the magnetically sensitive rubber polymer will change according to the friction force and be transmitted to the data acquisition card.

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

[0064] The motor stepper motor is placed in the sliding part to ensure that the device is not disturbed by the magnetic field when running.

[0065] According to the information sent by the host computer, the electromagnetic control device adaptively adjusts the magnetic field to adjust the contact friction between the non-magnetic carrier block and the magnetically sensitive rubber friction pair. m*n sensor units are placed in the form of an array distribution inside the magnetically sensitive rubber polymer and formed as a whole, and the contact surface is divided into m*n rows and columns of contact areas according to the position of the sensor, and the friction parameters of the contact area corresponding to a single sensor are accurately measured.

[0066] The array sensor unit can measure the contact friction state between the magnetic sensitive rubber and the carrier in real time, and transmit the sensor signal through Figure 6 The flexible conductive film network shown is transmitted to a data acquisition card and input into a computer host control unit for processing. The flexible film conductive network electrodes are correspondingly connected to each array sensor unit and output signals through a bus.

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

[0068] The driving device drives the carrier block to have contact friction with the magnetic sensitive rubber, causing deformation inside the magnetic sensitive rubber. The piezoresistive sensor embedded in the magnetic sensitive rubber measures the normal stress and tangential stress generated by the normal strain and tangential strain caused by the contact friction. Then, a beam-spring model is established to establish the relationship between stress and friction force, and the real-time friction force is calculated by the host computer.

[0069] Embodiment 4:

[0070] like Figure 8 As shown, a method for in-situ self-sensing friction of a magnetically sensitive rubber polymer comprises the following steps:

[0071] Step 1: Given a target friction force that needs to be achieved on a magnetically sensitive rubber polymer surface, the normal and shear stresses and their time-varying information of the magnetically sensitive rubber polymer are set as state variables as pre-input data for the beam-spring model;

[0072] Step 2: The host computer control module drives the non-magnetic conductive carrier block to move at a constant speed in any direction with a certain load on the surface of the magnetic sensitive rubber polymer;

[0073] Step 3: The flexible array sensor inside the magnetically 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 host computer, and 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;

[0074] Step 4: After obtaining the position of the force point of the magnetically sensitive rubber polymer, the normal stress and shear stress are directly measured through the sensing unit at the point, and then input into the beam-spring model of the host computer to obtain the magnitude and direction of the friction force at the point;

[0075] Step 5: By comparing with the target friction force input by the system, the electromagnetic control device adaptively adjusts the size of the magnetic field passing through the magnetically sensitive rubber polymer, thereby changing the surface friction of the magnetically sensitive rubber until the measured friction force is equal to the target friction force, and outputs the coordinates of the force point, magnetic field strength, and friction force size and direction at this time.

[0076] Through a large number of experiments in the early stage and simulation analysis and theoretical deduction in the later stage, the relationship between friction force and resistance change under magnetic field environment conditions is decoupled. By measuring the resistance signal, the friction characteristics such as the real-time magnetically controlled friction force and real-time friction factor of the magnetically sensitive rubber and the non-magnetic carrier block can be measured in real time and calculated.

[0077] The magnetically sensitive rubber polymer surface is divided into regions according to the distributed nodes of the flexible array sensor. When a node is subjected to external force, the sensor resistance around the node will change. The node region of the maximum force point can be determined through the resistance change matrix between rows and columns. Then, according to the node region, one or more matrix sensors around the node are matched, and the collected resistance signal is transmitted to the host computer. The host computer processes the stress change corresponding to the resistance value measured by the sensor to calculate the friction force. The resistance acquisition system of the matrix sensor will automatically match the matrix resistance value of 1*1, 2*2, 3*3... at the position for calculation according to the size of the force area of ​​the magnetically sensitive rubber surface.

[0078] The beam-spring model is based on the fact that the magnetically sensitive rubber surface always exists Figure 5 The various convex peaks shown are microscopically equivalent to a beam-spring model connected by a cantilever beam and a spring, and the following theoretical deduction is made for this model:

[0079] By performing mechanical analysis on the i-th microscopic beam-spring model along the x-axis, the following relationship can be obtained:

[0080]

[0081] is the friction force on the i-th beam-spring model in the x-axis direction at the microscopic level;

[0082] is the beam bending force in the x-axis direction on the i-th beam-spring model at the microscopic level;

[0083] is the elastic force in the x-axis direction on the i-th beam-spring model at the microscopic level.

[0084] Then the forces of all microscopic beams are synthesized to obtain the following formula:

[0085] F fx =F ex +F bx

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

[0087] Using the Euler-Bernoulli beam theory, the cantilever beam is subjected to a bending force f bx The deflection under action is:

[0088]

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

[0090] Then we calculate τ x With F bx Relationship:

[0091] in

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

[0093] Use empirical method to get F ex With σ z The relationship between: The coefficient k x and m x It is obtained through a large number of experimental calibrations in the early stage. x 、m x are the experimental coefficients, determined by repeated test calibration, σ z is the stress in the z-axis direction, i.e., the normal stress. When the sensor is at the critical point where it is about to start sliding, F ex In the saturated state, we express Then it is known We get is the critical normal stress, and finally we have:

[0094] (where τ x With σ z Directly measured by the sensor)

[0095] It represents the saturated beam bending force at critical sliding. After the friction force along the x-axis is obtained, the friction force along the y-axis can be obtained by the same method as above. Finally, the magnitude and direction of the total friction force can be obtained by vector synthesis:

[0096]

[0097] F fy is the total friction force on the contact area in the y-axis direction.

[0098] The working principle of the present invention is as follows: the present invention makes full use of the property that the magnetic sensitive rubber can change its surface morphology and thus change its surface friction under the control of the magnetic field, and innovatively embeds the array sensing unit inside the magnetic sensitive rubber polymer to realize the integration of sensing and control. That is, under the action of the external magnetic field, the friction control process of the magnetic sensitive rubber polymer is as follows: initially, a target friction force to be achieved is pre-set, and 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 drive device. During the movement, the array sensing unit senses the stress change information inside the magnetic sensitive rubber polymer at this time and transmits it to the host computer. The host computer derives the magnitude and direction of the friction force at this time through the pre-established stress-friction model, and then the host computer controls the electromagnetic device to change the magnetic field strength passing through the magnetic sensitive rubber, and changes the friction force on the surface of the magnetic sensitive rubber. The array sensing unit continuously senses the friction force until the pre-set friction force is reached, and outputs the coordinates of the force point, the magnetic field strength, and the magnitude and direction of the friction force at this time.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A magnetically sensitive rubber polymer, characterized in that: The invention comprises a magnetically sensitive rubber polymer matrix (1), a plurality of arrayed array sensing units (3) and a flexible conductive film network (17); the array sensing unit (3) comprises a lead electrode (2), a sensing unit outer sensitive layer (4), a sensing unit inner sensitive layer (5) and a sensing unit vertical sensitive layer (6); the sensing unit outer sensitive layer (4) and the sensing unit inner sensitive layer (5) are annular structures; the sensing unit vertical sensitive layer (6), the sensing unit inner sensitive layer (5) and the sensing unit outer sensitive layer (4) are arranged in sequence from the inside to the outside; the lead electrode (2) connects the sensing unit outer sensitive layer (4) and the sensing unit inner sensitive layer (5) and is connected to the electrode on the flexible conductive film network (17); the array sensing unit (3) and the flexible conductive film network (17) are inside the magnetically sensitive rubber polymer matrix (1); the array sensing unit (3) is arranged in an array according to the electrode sequence of the flexible conductive film network (17) at the bottom to ensure data transmission of each array sensing unit (3).

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

3. A magnetically sensitive rubber polymer according to claim 1 or 2, characterized in that: The magnetically sensitive rubber polymer matrix (1), the array sensing unit (3) and the flexible conductive film network (17) are formed in one piece by layering and embedding the magnetically sensitive rubber solution around the pre-prepared array sensing unit (3) and the flexible conductive film network (17) and then drying.

4. A friction in-situ self-sensing device for magnetically sensitive rubber polymers, characterized in that: The invention comprises the magnetically sensitive rubber polymer (9) as claimed in any one of claims 1 to 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 system; The loading drive module comprises a sliding member I (10), a sliding member II (11), a sliding member III (12), a pillar (13), a sliding guide rail I (14), a sliding guide rail II (15) and a non-magnetic carrier block (16); four of the pillars (13) are fixed on a base (7), four sliding members I (10) are respectively arranged on the four pillars (13), sliding members I (10) are respectively fixed at both ends of the sliding guide rail I (14) to form two parallel sliding rails, and sliding members III are respectively arranged on the two sliding rails. (12), the sliding members III (12) are connected by a sliding guide rail II (15), a sliding member II (11) is arranged on the sliding guide rail II (15), a non-magnetic conductive carrier block (16) is fixed below the sliding member II (11), a stepper motor drives the sliding member I (10) to drive the non-magnetic conductive carrier block (16) to move along the z-axis, the stepper motor drives the sliding member III (12) to drive the non-magnetic conductive carrier block (16) to move along the y-axis, and the stepper motor drives the sliding member II (11) to drive the non-magnetic conductive carrier block (16) to move along the x-axis; One end of the signal acquisition module is connected to the magnetically sensitive rubber polymer (9), and the other end is connected to the computer system to collect the resistance value of the array sensor unit in the magnetically sensitive rubber polymer.

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

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

7. A method for in-situ self-sensing friction of magnetically sensitive rubber polymers based on the device according to any one of claims 4 to 6, characterized in that: The following steps are involved: Step 1: Given a target friction force that needs to be achieved on a magnetically sensitive rubber polymer surface, the normal and shear stresses and their time-varying information of the magnetically sensitive rubber polymer are set as state variables as pre-input data for the beam-spring model; Step 2: The host computer control module drives the non-magnetic conductive carrier to move at a constant speed in any direction with a certain load on the surface of the magnetically sensitive rubber polymer; Step 3: The flexible array sensor inside the magnetically 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 host computer, and 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 position of the force point of the magnetically sensitive rubber polymer, the normal stress and shear stress are directly measured through the sensing unit at the point, and then input into the beam-spring model of the host computer to obtain the magnitude and direction of the friction force at the point; Step 5: By comparing with the target friction force input by the system, the electromagnetic control device adaptively adjusts the size of the magnetic field passing through the magnetically sensitive rubber polymer, thereby changing the surface friction of the magnetically sensitive rubber until the measured friction force is equal to the target friction force, and outputs the coordinates of the force point, magnetic field strength, and friction force size and direction at this time.

8. The friction in-situ self-sensing method of magnetic sensitive rubber polymer according to claim 7, characterized in that: The beam-spring model is F fx is the total friction force on the contact area in the x-axis direction, F ex is the total beam bending force in the contact area in the x-axis direction, F bx is the total elastic force on the contact area in the x-axis direction; represents the saturated beam bending force at critical slip; After obtaining the friction force along the x-axis, the friction force along the y-axis can be obtained by the same method as above. The magnitude and direction of the total friction force can be obtained by vector synthesis: Ffy is the total friction force on the contact area in the y-axis direction.

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