An electromagnetic adsorption force calculation method, device, equipment and medium for a wall-climbing robot

Abstract

The present invention discloses a method, device, equipment and medium for calculating the electromagnetic adsorption force of a wall-climbing robot, which relates to the technical field of wall-climbing robots and includes the following steps: establishing an equivalent magnetic circuit model of electromagnetic adsorption between the reinforcing bars on the inner wall of the wellbore and the internal electromagnets of the wall-climbing robot, establishing the relationship between the total magnetic resistance, current, number of turns of the winding coil and magnetic flux according to the equivalent magnetic circuit model of electromagnetic adsorption, and obtaining a first expression; introducing inductance into the equivalent magnetic circuit model of electromagnetic adsorption, establishing the relationship between winding voltage, current, magnetic flux, magnetic resistance and time change rate, and obtaining a second expression; based on the electromagnetic force calculation method of magnetic field energy, calculating the electromagnetic adsorption force of the wall-climbing robot according to the first expression and the second expression. The present invention considers the reasons affecting the calculation results and generating calculation errors, obtains the calculation formula for the electromagnetic adsorption force of the wall-climbing robot applied to the composite shaft wall structure, and the calculation results are accurate and can be directly applied and transformed.

Description

Technical Field

[0001] The present invention relates to the technical field of wall-climbing robots, and in particular to a method, device, equipment and medium for calculating the electromagnetic adsorption force of a wall-climbing robot. Background Art

[0002] During the construction and service period of a shaft, as the depth of the shaft increases, the probability and harm of safety accidents also continuously increase, and the difficulty and cost of accident handling also continuously increase. During the shaft construction period, various supporting systems and equipment are not yet complete, which makes the safety information monitored by monitoring equipment scattered at different positions in a relatively independent and closed state, and it is difficult to quickly and uniformly obtain complete and detailed data, and it is impossible to carry out effective early intervention and disaster warning. During the shaft service period, the special building structure of the shaft is not suitable for manual safety inspection, and it is also difficult to directly install and maintain the monitoring equipment and monitoring methods commonly used underground. This makes it impossible to accurately and real-time collect various safety information for this long-distance monitoring section of the vertical shaft, and it is also impossible to timely detect and eliminate potential hazards for dangerous situations that occur on the shaft wall. Therefore, to achieve the safety and efficiency of shaft construction and the daily safety inspection during the shaft service period, the key lies in improving the intelligence and unmanned operation of shaft safety monitoring and information collection. There is an urgent need to study shaft intelligent safety monitoring technologies and equipment to replace the current mainly manual inspection methods.

[0003] In recent years, mine intelligent inspection robots combined with coal mine safety monitoring and robot technology have been widely used in the field of underground safety detection. However, there are still few representative scientific research results and formed products in the application of intelligent robots in the important scenario of vertical shafts. The main reason is that it is difficult to break through the technical limitations of the robot carrier by the shaft building structure, and the wall-climbing robot using the negative pressure adsorption method itself cannot fully adapt to the relatively rough surface conditions of the shaft wall, and there will be a large power loss during the generation of the negative pressure adsorption force. Therefore, a more suitable adsorption technology for the shaft site conditions is needed as a supplement to the negative pressure adsorption to ensure the safety and stability of the wall-climbing robot, that is, the electromagnetic adsorption method is adopted.

[0004] Currently, wall-climbing robots using the electromagnetic adsorption method are generally applied to planar magnetic conductor mechanisms. Whether using the permanent magnet adsorption method or the electromagnetic adsorption method, the adsorption force calculation formula is relatively simple, and there is a lack of in-depth research on the calculation of the electromagnetic adsorption force of non-planar magnetic conductors, which is not suitable for the complex environment of the shaft. Summary of the Invention

[0005] The present invention provides a method, device, equipment and medium for calculating the electromagnetic adsorption force of a wall-climbing robot, which solves the problem that the wall-climbing robot using the electromagnetic adsorption method is generally applied to a planar magnetic conductor mechanism, and its adsorption force calculation formula is relatively simple. There is a lack of in-depth research on the calculation of the electromagnetic adsorption force of non-planar magnetic conductors, and it is not suitable for the complex environment of the wellbore.

[0006] The present invention provides a method for calculating the electromagnetic adsorption force of a wall-climbing robot, which is used for the inspection of the wellbore. The method includes the following steps:

[0007] Establish an equivalent magnetic circuit model of electromagnetic adsorption between the steel bars on the inner wall of the wellbore and the electromagnets inside the wall-climbing robot. According to the equivalent magnetic circuit model of electromagnetic adsorption, establish the relationship between the total magnetic resistance, current, number of turns of the winding coil and magnetic flux of the magnetic circuit, and obtain the first expression;

[0008] Introduce inductance into the equivalent magnetic circuit model of electromagnetic adsorption, and establish the relationship between winding voltage, current, magnetic flux, magnetic resistance and time change rate to obtain the second expression;

[0009] Based on the electromagnetic force calculation method of magnetic field energy, obtain the electromagnetic adsorption force of the wall-climbing robot according to the first expression and the second expression.

[0010] Preferably, establishing the equivalent magnetic circuit model of electromagnetic adsorption between the steel bars on the inner wall of the wellbore and the electromagnets inside the wall-climbing robot includes the following steps:

[0011] Apply an electromagnet outside the steel bar to obtain a magnetic circuit system;

[0012] Divide the overall magnetic circuit nodes according to the structural characteristics of the components in the magnetic circuit system to obtain multiple magnetic circuit units;

[0013] Use the magnetic resistance of each magnetic circuit unit to represent the magnetomotive force source of the magnetic circuit node, and establish an equivalent magnetic circuit model of electromagnetic adsorption.

[0014] Preferably, the first expression is as follows:

[0015] F = NI = (R t + 2R ud + R uw + 2R g )Φ = R z Φ

[0016] In the formula, F is the total magnetomotive force source, N is the number of turns of the winding coil, I is the system current, R t is the magnetic resistance of the steel bar material, R ud is the magnetic resistance at both ends of the electromagnet, R uw is the magnetic resistance of the bottom iron core of the electromagnet, R g is the magnetic resistance of the concrete gap, Ф is the magnetic flux, R zis the total magnetic resistance.

[0017] Preferably, an inductor is introduced into the electromagnetic adsorption equivalent magnetic circuit model to establish the relationship between the winding voltage, current, magnetic flux, magnetic resistance, and time change rate, including the following steps:

[0018] An inductor is introduced into the electromagnetic adsorption equivalent magnetic circuit model to obtain the relationship between the magnetic flux linkage and current of the winding;

[0019] According to the above relationship and Faraday's law, a second expression is obtained;

[0020] The second expression is as follows:

[0021]

[0022] In the formula, U is the system voltage, R r is the winding resistance, λ is the winding magnetic flux linkage, and t is the time variable.

[0023] Preferably, before obtaining the electromagnetic adsorption force of the wall-climbing robot according to the first expression and the second expression, an edge magnetic flux needs to be introduced into the electromagnetic adsorption equivalent magnetic circuit model to correct the gap magnetic resistance of the concrete in the first expression, and a third expression is obtained, including the following steps:

[0024] The gap magnetic resistance is divided into outer corner edge magnetic resistance, inner corner edge magnetic resistance, front edge magnetic resistance, and rear edge magnetic resistance;

[0025] According to the magnetic voltage drop formula, the magnetic field strength of the outer corner edge magnetic flux is obtained, and the outer corner edge magnetic flux expression is obtained according to the magnetic flux definition;

[0026] The magnetic field strength of the outer corner edge magnetic flux and the outer corner node area are substituted into the outer corner edge magnetic flux expression to obtain the outer corner edge magnetic resistance;

[0027] Based on the outer corner edge magnetic resistance and the length values of each node of the inner corner, front edge, and rear edge, the inner corner edge magnetic resistance, front edge magnetic resistance, and rear edge magnetic resistance are obtained;

[0028] The gap magnetic resistance is added to the outer corner edge magnetic resistance, inner corner edge magnetic resistance, front edge magnetic resistance, and rear edge magnetic resistance to obtain a new gap magnetic resistance;

[0029] The third expression is as follows:

[0030] R gz = 2(R g + R bw + R bn + 2R bq )

[0031] In the formula, R gc is the new gap magnetic resistance, Rbw is the external corner edge magnetoresistance, R bn is the internal corner edge magnetoresistance, R bq is the front edge magnetoresistance.

[0032] Preferably, for the electromagnetic force calculation method based on magnetic field energy, the electromagnetic adsorption force of the wall-climbing robot is obtained according to the first expression and the second expression, including the following steps:

[0033] According to the second expression, it is obtained that the system electromotive force is equal to the change rate of the winding magnetic flux with respect to time. Multiply the change rate of the winding magnetic flux with respect to time by the system current and integrate to obtain the electrical energy expression;

[0034] Integrate the electromagnetic adsorption force after introducing the distance variable to obtain the mechanical energy expression;

[0035] Add the electrical energy expression and the mechanical energy expression to obtain the magnetic energy expression;

[0036] Differentiate the magnetic energy expression to obtain the first expression of the magnetic energy differential;

[0037] In a single-resistance branch, it is expressed according to the magnetomotive force source and the energy storage expressions of the magnetic flux for all branches;

[0038] Based on the first expression, obtain the magnetomotive force source of the branch related to the mechanical displacement, and combine the energy storage expressions of all branches to obtain the total energy storage expression of the branch related to the mechanical displacement;

[0039] Differentiate and transform the total energy storage expression of the branch related to the mechanical displacement to obtain the second expression of the magnetic energy differential;

[0040] According to Kirchhoff's law, simplify the first expression and the second expression of the magnetic energy differential, and substitute the third expression to obtain the expression of the electromagnetic adsorption force.

[0041] Preferably, the expression of the electromagnetic adsorption force is as follows:

[0042]

[0043] In the formula, F j is the electromagnetic adsorption force, x is the variable distance of the gap, b is the branch, R b is the branch magnetoresistance, Ф b is the branch magnetic flux, F b is the branch magnetomotive force source, B j is the set of branch magnetic fluxes related to the mechanical displacement.

[0044] An electromagnetic adsorption force calculation device for a wall-climbing robot, comprising:

[0045] A building module is used to establish an equivalent magnetic circuit model of electromagnetic adsorption between the reinforcing bars on the inner wall of the shaft and the internal electromagnets of the wall-climbing robot. Based on the equivalent magnetic circuit model of electromagnetic adsorption, the relationship between the total magnetic resistance of the magnetic circuit, current, number of turns of the winding coil, and magnetic flux is established to obtain a first expression.

[0046] An introduction module is used to introduce inductance into the equivalent magnetic circuit model of electromagnetic adsorption, establish the relationship between winding voltage, current, magnetic flux, magnetic resistance, and the rate of change with time, and obtain a second expression.

[0047] A calculation module is used to calculate the electromagnetic adsorption force of the wall-climbing robot based on the electromagnetic force calculation method of magnetic field energy, according to the first expression and the second expression. A computer device includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it implements the above-mentioned method for calculating the electromagnetic adsorption force of the wall-climbing robot.

[0048] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, it implements the above-mentioned method for calculating the electromagnetic adsorption force of the wall-climbing robot.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0050] The present invention constructs an equivalent magnetic circuit model of electromagnetic adsorption between the reinforcing bars on the inner wall of the shaft and the internal electromagnets of the wall-climbing robot based on the actual scenario, and based on the equivalent magnetic circuit model of electromagnetic adsorption, the relationship between the total magnetic resistance of the magnetic circuit, current, number of turns of the winding coil, and magnetic flux is established to obtain a first expression; further, inductance is introduced into the equivalent magnetic circuit model of electromagnetic adsorption to establish the relationship between winding voltage, current, magnetic flux, magnetic resistance, and the rate of change with time, and obtain a second expression. Finally, based on the electromagnetic force calculation method of magnetic field energy, the electromagnetic adsorption force of the wall-climbing robot is calculated according to the first expression and the second expression. The present invention considers the reasons affecting the calculation results and generating calculation errors, obtains a calculation formula for the electromagnetic adsorption force of the wall-climbing robot applied to the composite shaft wall structure, the calculation result is accurate, the overall calculation amount is not large, and it can be directly applied for transformation. Description of the Drawings

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0052] Figure 1 It is the normal magnetization curve diagram of the reinforcing bar material of the present invention;

[0053] Figure 2 Synthetic magnetization curve of the steel bar material of the present invention;

[0054] Figure 3 Schematic diagram of the magnetic field in the steel bar of the present invention;

[0055] Figure 4 Effect diagram of the steel bar electromagnet of the present invention;

[0056] Figure 5 Schematic diagram of the node division of the present invention;

[0057] Figure 6 Schematic diagram of the equivalent magnetic circuit of the present invention;

[0058] Figure 7 Schematic diagram of the magnetic flux-current change curve of the present invention;

[0059] Figure 8 Schematic diagram of the tangential component of the magnetic field at the junction of the protective layer and the core cylinder surface of the present invention;

[0060] Figure 9 Schematic diagram of the normal component of the magnetic field at the junction of the protective layer and the core cylinder surface of the present invention;

[0061] Figure 10 Schematic diagram of the gap edge magnetic flux path of the present invention;

[0062] Among them, (a): front schematic diagram, (b): side schematic diagram;

[0063] Figure 11 Front schematic diagram of the edge magnetic flux of the present invention;

[0064] Figure 12 Side schematic diagram of the edge magnetic flux of the present invention;

[0065] Figure 13 Schematic diagram of the geometric structure of the electromagnet coil of the present invention;

[0066] Figure 14 Flow chart of a method for calculating the electromagnetic adsorption force of a wall-climbing robot of the present invention. Detailed implementation manners

[0067] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0068] Refer to Figure 14, the present invention provides a method for calculating the electromagnetic adsorption force of a wall-climbing robot, which includes the following steps:

[0069] The first step: Establish an equivalent magnetic circuit model of electromagnetic adsorption between the steel bars on the inner wall of the shaft and the electromagnets inside the wall-climbing robot.

[0070] In the construction of deep shafts in China, the freezing method is generally adopted. In shaft construction using the freezing method, double-layer reinforced concrete composite shaft lining is generally used for permanent support. The support structure is divided into an outer shaft lining and an inner shaft lining. The outer shaft lining is close to the surrounding rock freezing wall and mainly bears the freezing pressure, playing a role of temporary support during shaft construction. The inner shaft lining is the main body of the permanent shaft lining, mainly bearing the net water pressure and playing a role of isolating groundwater during the service process of the shaft. After secondary lining, grouting is carried out on the interlayer between the inner and outer shaft linings to make the inner and outer shaft linings form a whole and jointly bear various stresses. In the permanent support structure of the double-layer reinforced concrete composite shaft lining, the most important thing is the selection of the steel bar grade and the calculation of the reinforcement ratio for the inner linings of the inner and outer shaft linings. If the selected steel bar grade is too low or the reinforcement is insufficient in the design, it will cause insufficient bearing capacity of the support structure, and safety accidents such as cracking, deformation, and water seepage will occur in the inner shaft lining under the action of lateral pressure. If high-grade steel bars are pursued and the density of the steel bar mesh is increased in the design, it will cause problems such as increased project cost and extended construction period. Moreover, the excessive use of steel bar materials will increase the thickness of the shaft lining, resulting in too large a temperature difference between the inner and outer shaft linings, causing temperature cracks in the shaft lining and affecting the impermeability and durability of the shaft lining.

[0071] China stipulates that the selection of steel bar models and the determination of steel bar spacing should be calculated according to the "Code for Design of Concrete Structures" (GB50010-2015). The strength design value of the shaft lining material is deduced based on parameters such as shaft depth, inner wall thickness, inner wall radius, standard value of net water pressure, and load partial coefficient, and then the strength design value and reinforcement ratio of the steel bars are calculated. It should be noted that the compressive strength of steel bars is much greater than that of concrete. It can be seen that the selection of steel bar models and the design of steel bar spacing are particularly important in the calculation of the bearing capacity of the composite shaft lining. As the adsorption object of the electromagnetic adsorption mechanism of the wall-climbing robot, the grid structure composed of the horizontal and vertical steel bars of the inner shaft lining is the key research point.

[0072] Regulations have been made on the minimum diameter and maximum and minimum spacing of steel bars for different shaft depths. In shafts deeper than 300m, the diameter of steel bars shall not be less than 20mm. In shallow depths, the diameter of steel bars used shall not be less than 16mm. In actual design, for the consideration of stress redundancy, steel bars with a diameter greater than 20mm are basically selected for shallow-layer steel bar ratios, and steel bars with a diameter of 25mm - 32mm are basically selected for deep-layer steel bar ratios. In terms of steel bar spacing, it is stipulated that the circumferential and longitudinal steel bar spacings shall not be greater than 300mm and shall not be less than 150mm. Therefore, in the structural design of the wall-climbing robot, it is necessary to design the structural dimensions of the coupling adsorption mechanism of the wall-climbing robot in a targeted manner.

[0073] A reinforced concrete structure is a stable mechanical structure composed of an inner steel bar mesh and an outer layer of concrete, which jointly bear various stresses applied to the structure. It is one of the most basic composite materials widely used in civil engineering. In the construction project of coal mine shafts, the reinforcing bars in the lining of the composite shaft wall generally use deformed bars with diameters of 20mm, 25mm, 28mm, and 32mm. The deformed bars are ribbed deformed bars, and the ribs can increase the bonding force between the steel bars and the concrete, thus increasing the overall bearing capacity of the structure. The magnetic permeability calculated by the formula is the absolute magnetic permeability of the magnetic medium, with the unit of henry per meter (H / m). In engineering practice and scientific research, to measure the magnetic conductivity of different magnetic media, the magnetic permeability of vacuum is defined as the reference magnetic permeability μ0, and its value is μ0 = 4π×10 -7 H / m. The ratio μ of the absolute magnetic permeability of other magnetic media to the magnetic permeability of vacuum r is defined as the relative magnetic permeability of the magnetic medium. The formula for relative magnetic permeability is:

[0074]

[0075] In the formula: μ is the absolute magnetic permeability, H / m; μ0 is the magnetic permeability of vacuum; μ r is the relative magnetic permeability.

[0076] For the experimental measurement of the magnetic permeability of engineering materials, the commonly used method is to process the material to be measured into a toroidal closed magnetic core with fixed dimensions, wind a wire coil outside it, measure the inductance of the coil after applying an excitation current, and calculate and determine it in combination with the inner and outer radii, thickness, and the number of turns of the winding of the closed magnetic ring. The normal magnetization curve of the steel bar material obtained by this method is shown in Figure 1 , according to the magnetic permeability formula μ = B / H, the value of μ is equal to the slope of the line from the origin to the corresponding point on the magnetization curve. In the process of continuously increasing the applied magnetic field H, the value of the magnetic induction intensity B first increases continuously with the increase of the magnetic field intensity H, and the slope of the corresponding point on the magnetization curve also increases continuously, and reaches the maximum value at a certain point. At this time, the maximum magnetic permeability μ m, at this time, the electromagnetic system reaches magnetic saturation. After that, the growth rate of B slows down. Eventually, the relationship between B and H becomes similar to the situation in a vacuum. The magnetic permeability curve also rapidly drops after reaching the peak, and the value of μ also continuously decreases as H increases. The magnetic permeability of the normal magnetization curve generated by this method shows a continuously changing non-linear trend, which is relatively accurate for determining the magnetic conductivity of steel bars. However, for the research purpose of the present invention, the safety monitoring wall-climbing robot using the electromagnetic adsorption method needs to adsorb the steel bars in the shaft wall through the concrete protective layer. There is an air gap in the magnetic circuit, and the shape of the steel bar is rod-shaped. After being magnetized by the external magnetic field, a demagnetizing field opposite to the direction of H will be generated inside, resulting in a large error between the value of B and the measured value by the normal method. Therefore, a ring-shaped closed magnetic core with an air gap should be used for re-measurement and calculation, and the magnetization characteristics of the magnetic core and the magnetization characteristics of the air gap should be synthesized and analyzed to obtain the synthetic magnetization curve of the steel bar material, as Figure 2 , the magnetic field strength of the magnetic ring with an air gap is H δ +H C , the magnetic field strength of the magnetic ring without an air gap is H δ , the magnetic ring with an air gap and the magnetic ring without an air gap have the same magnetic flux density. The magnetic field strength of the magnetic ring with an air gap is mainly stored in the air gap, and the energy stored in the magnetic core is very small. The air gap can generate a large magnetic resistance, which can offset the non-linear material characteristics of the steel bar, making the magnetization curve show a relatively good linear characteristic. Moreover, the demagnetization performance of the air gap can effectively eliminate the residual magnetic induction B of the magnetic core r , making the obtained effective magnetic permeability μ e more accurate relatively.

[0077] As another component of the reinforced concrete structure, concrete is mixed with cement, sand, aggregate, water and some additives. The most important component among them is cement. The electromagnetic characteristics of cement directly determine the magnetic conductivity of concrete materials. Portland cement is commonly used in modern engineering construction.

[0078] The inner layer steel bars of the shaft composite shaft wall have strong magnetic conductivity and are relatively stable. Although the concrete protective layer has weak magnetic conductivity, it belongs to the paramagnetic property and has no diamagnetism. As a magnetic medium, its relative magnetic permeability is greater than that of air. In the case of shaft wall water spray, although the relative magnetic permeability of water will change with the change of temperature, generally the change is not large, and it is also approximately equal to the relative magnetic permeability of air. Therefore, the moisture content of the concrete protective layer will not affect its magnetic conductivity.

[0079] The adsorption principle of the electromagnetic adsorption device of the wall-climbing robot for the inner layer steel bars of the shaft wall is based on Kirchhoff's law, following Kirchhoff's magnetic motive force law, magnetic flux law and magnetic circuit Ohm's law, Figure 3Take a section of steel bar as the electromagnetic material to analyze the relationship between the magnetic voltage drop and magnetic flux in the equivalent magnetic circuit. Let L be the length of the intercepted steel bar material, A be the cross-sectional area of the steel bar, Ф be the magnetic flux passing through the cross-section of the steel bar by the external magnetic field, and F be the magnetic voltage drop formed along the length of the steel bar.

[0080] Assume that the magnetic field intensity of the external magnetic field is uniform. According to the definition of magnetic voltage drop, the magnetic voltage drop within the closed path L is:

[0081]

[0082] Assume that the magnetic flux Ф passing through the cross-section A of the steel bar does not flow out during the process of passing through the steel bar material, and the magnetic flux direction is perpendicular to A. Then the magnetic flux passing through both ends of the steel bar material is:

[0083]

[0084] According to Ohm's law of magnetic circuit, Equation (1), Equation (2), and Equation (3), we can obtain:

[0085]

[0086] Where: R is the magnetic resistance of the tested steel bar, H; the expression is:

[0087]

[0088] Where: P is the magnetic conductance of the electromagnetic material, 1 / H; it is the reciprocal of the magnetic resistance.

[0089] According to the derived formula, the magnetic resistance and magnetic conductance of the electromagnetic material are related to its own length, cross-sectional area, and magnetic permeability. For electromagnetic materials with irregular shapes, the above expressions are also applicable.

[0090] Based on the steel bar ratio on the inner wall of the wellbore and the magnetic conductivity of reinforced concrete, establish an equivalent magnetic circuit model for electromagnetic adsorption, and establish the relationship between the total magnetic resistance, system current, number of turns of the winding coil, and magnetic flux.

[0091] Apply an electromagnet to the outside of the steel bar material in Figure 4 to form a closed magnetic circuit system, simulate the physical state in the real scenario, establish an equivalent magnetic circuit model (MEC), analyze the changes and correlations of various parameters and variables in the electromagnetic field. Assume that the steel bar model and the electromagnet are both in a static state, they are in the same plane, and there is no angular deviation, r d and r w are the depth and width of the cross-section of the wire winding of the electromagnet, u e , u s , u d and u lare the width of the end part, the height of the end part, the height of the yoke part, and the width of the side surface. The length of the steel bar material is equal to that of the electromagnet, and it is the width t of one slot part w and the sum of the widths u of the two end parts e . The steel bar has a cylindrical structure, and its side cross-section is a circle with a radius of r. Therefore, the diameter t of the steel bar material d = u l = 2r, and g is the height of the gap between the electromagnet and the steel bar material

[0092] According to the structural characteristics of each component in the magnetic circuit system, nodes are divided for the overall magnetic circuit to form different lumped magnetic circuit units. Using the method of first units and then the whole, according to the geometric shape of the electromagnetic material, the structural part with a regular shape is divided into a node area. The current direction of the wire winding in the electromagnetic system passes through the paper surface from the outside to the inside in the slot of the electromagnet and passes through the paper surface from the inside to the outside below the electromagnet. According to the right-hand rule, the magnetic flux direction in the whole magnetic circuit system is clockwise through each node. In Figure 5 , the positions and shapes of each node are marked. Assuming that N0 is the grounding point and the starting point of magnetic flux circulation, the magnetic flux flows from N0 to N1, makes a right-angle turn at N1 and then flows to N2. When the magnetic flux passes through N2, there is no turning behavior of the magnetic flux. At the N3 node, the magnetic flux also has a right-angle turn after passing through the first node module. The same is true for N4 and N5, only the magnetic flux directions are different. From this, it can be seen that the shape of the node is related to the behavior of the magnetic flux flowing through

[0093] Both the circuit and the magnetic circuit system are based on Kirchhoff's laws. In Figure 6 , the whole magnetic circuit is divided using the method of resistance circuits. The magnetic resistances of each magnetic circuit unit are used to represent the magnetic circuit nodes and the magnetomotive force sources. R t represents the magnetic resistance of the steel bar material, R ud represents the magnetic resistances of the two end parts of the electromagnet, R uw represents the magnetic resistance of the bottom iron core of the electromagnet. Due to the non-linear characteristics of ferromagnetic materials, the above magnetic resistances are all functions of the magnetic flux density and the magnetic field strength. The expressions of the magnetic resistances of each part can be expressed as:

[0094]

[0095] The length of the above lumped magnetic circuit units is based on the average distance between nodes. μ t is the absolute magnetic permeability of the steel bar, μ d is the absolute magnetic permeability of the iron core of the electromagnet. The magnetic conductivity of the concrete gap is equivalent to that of air. The magnetic permeability of air has linear characteristics and does not form a functional relationship with the magnetic flux and magnetic field strength flowing through it. The gap magnetic resistance is mainly affected by the gap height, the adsorption area, and the relative magnetic permeability of the material. Therefore, the expression of the magnetic resistance of the concrete protective layer gap is:

[0096]

[0097] Figure 6 The magnetomotive force source F of the middle magnetic circuit system is F = NI, where N is the number of turns of the winding coil and I is the current passing through the winding wire. The sum of the magnetic voltage drops along the closed loop is equal to the sum of the magnetomotive force sources of this loop. Therefore, during the process where the magnetic flux passes through N0―N1―N2―N3―N4―N5―N0 in sequence, the sum of the magnetic voltage drops of each section of magnetic resistance is equal to the sum of the magnetomotive force sources of the entire magnetic circuit system:

[0098] F = NI = (R t + 2R ud + R uw + 2R g )Φ = R z Φ (8)

[0099] In the formula: R z is the total magnetic resistance of the electromagnetic circuit, H; the magnetic flux Ф = NI / R z .

[0100] Step 2: Introduce inductance to the equivalent magnetic circuit model of electromagnetic adsorption, and establish the relationship between the system voltage, winding resistance, system current, total magnetic resistance, number of turns of the winding coil, magnetic flux, and the rate of change of winding magnetic chain with respect to time.

[0101] The winding plane wrapped around the iron core of the electromagnet is in the same direction as the iron core plane. The magnetic flux perpendicular to the cross-section of the iron core also perpendicularly passes through the winding plane during the flowing process. The magnetic flux passing through a single-turn coil is the same as the constant magnetic flux Ф, and the magnetic flux passing through an N-turn coil can be expressed by the magnetic chain λ = NФ.

[0102] Figure 7 shows the change process of the magnetic chain and internal current of a general single winding. Without considering the mutual inductance between multiple windings and ignoring the hysteresis effect. λ a and I a respectively represent the values of the winding magnetic chain and internal current at point a. The ratio of λ a to I a represents the absolute inductance L abs of the electromagnetic system at point a, and the expression is:

[0103]

[0104] Similarly at point a, the ratio of the increment of the magnetic chain and current in the adjacent region, that is, the slope of the curve in the figure at a, is the incremental inductance L inc of the electromagnetic system at point a, and the expression is:

[0105]

[0106] Inductance is an important physical quantity. Introducing inductance can establish the connection between the magnetic flux linkage of the winding and the internal current, and further establish the connection between voltage, current, magnetic flux, magnetic conductance, and the rate of change with time, combining electromagnetics and circuits into an integrated system for analysis. In the equivalent magnetic circuit, the curve of the change in magnetic flux linkage λ and current I is actually a straight line passing through the endpoints with a slope of L, showing an obvious linear change. In the linear change, the absolute inductance L abs and the incremental inductance L inc have the same numerical value.

[0107] According to Faraday's law, the voltage applied across the two ends of the winding in an electromagnetic device is equal to the sum of the voltage drop caused by the resistance of the winding itself and the rate of change of the magnetic flux linkage of the winding with respect to time. Let the voltage across the two ends of the winding in the equivalent magnetic circuit model be U, and the winding resistance be R r , the system voltage is:

[0108]

[0109] According to the formula, in the unit equivalent magnetic circuit model, the system voltage is composed of the winding voltage and the magnetic circuit voltage. The voltage level is directly proportional to the flowing current, the winding resistance, and the number of turns of the coil, and inversely proportional to the total magnetic resistance of the electromagnetic circuit. When the fixed physical quantities of the system remain unchanged, the greater the change in the system current per unit time, the greater the impact on the system voltage. Therefore, in the design of electromagnetic adsorption devices, wire materials with lower resistance values should be selected, the number of turns of the winding should be appropriately reduced, and the structural dimensions of the electromagnet should be reasonably designed to achieve the purpose of reducing the system current and voltage and minimizing the system power consumption.

[0110] Step 3: Introduce the fringing flux into the equivalent magnetic circuit model of electromagnetic adsorption to obtain a new total magnetic resistance.

[0111] Although both magnetic circuits and electric circuits follow basic physical laws, the behaviors of magnetic flux and current in air are different, which is determined by their physical properties. Generally, the conductivity of conductors and air differs by many orders of magnitude, and some can reach dozens of orders of magnitude. Therefore, it is basically impossible for current to flow in air, and the situation of leakage current does not need to be considered. However, compared with air or other materials with a magnetic permeability similar to that of air, the magnetic permeability of ferromagnetic materials only differs by 3 - 4 orders of magnitude, and the magnetic field gap will form a relatively large vacuum cross-section. This allows the magnetic flux to not be limited to the specified magnetic path direction and cross-section, and will pass through the gap along a divergent path and then enter other magnetic conductors, forming fringing flux. Therefore, in the analysis of equivalent magnetic circuits with gaps, the influence of fringing flux on the magnetic circuit must be considered.

[0112] In Figure 6In the equivalent magnetic circuit model, the magnetic flux has to pass through two gaps of distance g when it reaches N3 from N2, penetrates the steel bar material, and then reaches N5 from N4. When the magnetic flux passes through the gap, it can be considered that the magnetic flux always passes through and enters the surface of the core column vertically. This is because the tangential component and normal component of the magnetic flux in the gap and the core column are different, and the normal component is much larger than the tangential component.

[0113] like Figure 8 In, H qu and H qj They represent the tangential components of the magnetic field intensity inside the core column and in the concrete cover, respectively. Assuming that the path height ε approaches 0, according to Ampere's law H qu l=H qj l, l is the diameter of the iron core. It can be seen that the tangential component of the magnetic field intensity inside the iron core is the same as the tangential component in the concrete cover. According to the magnetic permeability formula, the relationship between the magnetic induction intensities in the tangential direction is:

[0114]

[0115] The magnetic permeability of the concrete cover is replaced by the vacuum magnetic permeability, μ r is the relative magnetic permeability of the electromagnet core material. The electromagnet core is made of ferromagnetic material, and its relative magnetic permeability μ r The value is very large. It can be seen from formula (12) that the magnetic flux density in the concrete protective layer is much smaller than the magnetic flux density inside the iron core in the tangential direction, that is, there is basically no magnetic flux flowing in the protective layer in the direction parallel to the surface of the iron core column.

[0116] Figure 9 Middle, B fu and B fj They represent the normal components of the magnetic flux density inside the core column and in the concrete cover, respectively. Assuming that the height of the penetration surface ε approaches 0, it is guaranteed that there will be no magnetic flux leakage from the side. According to Gauss's law B fu A=B fj A, it can be seen that the normal component of the magnetic flux density in the concrete cover is the same as the normal component of the magnetic flux density inside the core column, and the component in the tangential direction can be ignored. Therefore, when the main magnetic flux passes through and enters the surface of the core column, only the magnetic flux perpendicular to the plane of the core column passes through the concrete cover.

[0117] In the analysis of the equivalent magnetic circuit model, the total magnetic resistance R of the entire magnetic circuit can be obtained by calculating the magnetic resistance of each magnetic circuit unit. z , but the magnetic circuit reluctance is not accurate because the gap reluctance R is calculated. gOnly the main magnetic flux in the vertical direction was considered at that time, thus the influence of the fringing flux on the gap magnetic resistance was not taken into account. In fact, when the magnetic flux passes through the gap from the core cylinder surface into the steel bar material, in addition to the main magnetic flux entering vertically, it will also enter along the non-straight path at the inner and outer corners and the front and back surfaces of the gap, causing the value of the gap magnetic resistance R g to change.

[0118] For example Figure 10 , when the gap distance is very small or the area through which the main magnetic flux passes is much larger than the gap distance, the influence of the fringing flux on the entire magnetic circuit can be ignored. However, the structural characteristics of the reinforced concrete composite shaft lining require that the outer surface of the outer-edge steel bars must be covered with a concrete protective layer, and there are also specific requirements for the minimum distance from the outer edge of the steel bars to the concrete surface. According to the provisions of the "Code for Design of Concrete Structures" (GB50010-2010), the net protective layer thickness of the stressed steel bars should reach 50 mm. In practical applications, due to the limitations of the steel bar model, steel bar spacing, the weight of the robot itself, and the design dimensions, the column surface area of a single electromagnet in the electromagnetic adsorption system of the intelligent wall-climbing robot cannot be large enough to ignore the gap thickness. Therefore, in the research and calculation of the present invention, the influence of the fringing flux at the gap edge on the total resistance of the entire electromagnetic system needs to be considered.

[0119] The path of the fringing flux at the gap edge of the electromagnetic system depends on the shape, size, position, and angle of the steel bar material and the electromagnet column surface. For example Figure 11 , since in practice, for the steel bars on the inner wall of the shaft, whether horizontally or vertically, both ends of the steel bars are connected to other steel bars by welding and there are no breakpoints in the middle. Therefore, in the calculation of the fringing flux at the gap edge of the magnetic circuit, the form in Figure 11 is adopted. The steel bar material extends horizontally at the left and right ends of the core column end. The fringing flux flowing out from the core column end enters the steel bar material along the inner and outer corner paths. On the side, as shown in Figure 12 , the fringing flux at the front edge of the core column end penetrates out of the paper surface and then penetrates into the paper surface to enter the front surface of the steel bar material. The direction of the fringing flux at the back edge of the core column end is the same as that at the front, and it enters from the back surface of the steel bar material. The front and back fringing flux paths are the same and the lengths are equal.

[0120] Similarly, it is assumed that the steel bar model and the electromagnet are both in a static state, they are in the same plane, there is no angular deviation, and the magnetic flux flows out and into the electromagnetic material in the vertical direction. t d is the diameter of the steel bar model, t d = 2r, w represents the length of each corresponding node, l represents the length of each fringing flux path, g is the gap height, and u l is the width of the core column side surface.

[0121] N a and N bIt is an outer corner node of the edge flux. As can be seen from the figure, the length of the outer corner edge flux path is the gap length plus one-fourth of the arc length, that is, l = g + πr / 2. According to the magnetic voltage drop formula, the magnetic field strength of the outer corner edge flux is obtained as follows:

[0122]

[0123] According to the definition of magnetic flux, the outer corner edge flux is:

[0124]

[0125] S A is the area of node N a , dS = u l r. It should be noted that the value of the radius r is a variable, and the outer corner edge flux path changes with the change of r. The value range of the variable r is between [0, w]. Substituting dS into Equation (14), the outer corner edge flux function can be obtained as follows:

[0126]

[0127] From Equation (4), the outer corner edge magnetic resistance can be obtained as follows:

[0128]

[0129] Corresponding Figure 7 , it is determined that the value of the node length w should be the smaller value between the diameter of the steel bar model and the end length of the electromagnet, that is, w = min(t d , u s + u d ). Substituting it into the above formula:

[0130]

[0131] Observation Figure 11 It can be found that the edge flux paths of the inner and outer corners are the same and the lengths are equal. However, for the inner corner, the value of the node length w needs to consider the depth and width of the electromagnet slot. w cannot exceed the depth u s of the slot, nor can it exceed half of the slot width t w / 2. Otherwise, nodes N c and N d will overlap with the nodes at the inner corners of the other end iron core column. Therefore, in the plane, the calculation formulas for the inner and outer corners of the electromagnet iron core column are the same, but the value of the node length w is different. The inner corner node length should take the smaller value between the slot depth and the slot width / 2, that is, w = min(u s , t w / 2). Without considering the edge flux intersecting with the winding, the inner corner edge magnetic resistance is obtained as follows:

[0132]

[0133] The front and rear edge fluxes of the air gap are calculated below. According to Figure 12 it can be seen that the length of the front edge flux path is the sum of the air gap length and half of the arc length, i.e., l = g + πr. The value of the node length w is the same as that of the outer corner node length. The calculated formula for the front edge reluctance is:

[0134]

[0135] According to Figure 12 and the above calculation results, it can be seen that the front and rear edge flux paths of the air gap are the same, with equal lengths and the same calculation formula. The lengths of nodes N f and N e have the same value. Therefore, the rear edge reluctance is numerically equal to the front edge reluctance, i.e., R bq = R bh .

[0136] In the equivalent magnetic circuit model (MEC), the total reluctance expression of the air gap reluctance after adding each edge reluctance is:

[0137] R gz = 2(R g + R bw + R bn + 2R bq ) (20)

[0138] In the previous equivalent magnetic circuit analysis, for the convenience of deriving the formula, the influence of the winding resistance on the system power consumption was temporarily ignored. According to Equation (11), the voltage applied across the winding is the sum of the voltage drop caused by the resistance of the winding itself and the rate of change of the winding magnetic flux with respect to time. That is, the winding voltage plus the equivalent magnetic circuit voltage equals the total voltage of the electromagnetic adsorption system. As a relatively independent circuit unit, the winding resistance can be excluded from the equivalent magnetic circuit. However, for the entire electromagnetic adsorption system, the winding resistance has a direct impact on the total voltage and total power of the system, and thus also affects the branch flux and electromagnetic adsorption force of the equivalent magnetic circuit.

[0139] As Figure 13 , the left side is the side view of the coil, and the electromagnet yoke core passes through the middle of the coil. The right side is the cross-sectional view of the coil, where one circular element represents one turn of the coil. The dimensions marked in the figure are the same as those in Figure 7 the effect diagram of the reinforced concrete electromagnet. From the electrical conductor resistance expression:

[0140]

[0141] In the formula: L is the conductor length, in m; A is the conductor cross-sectional area, in m2; σ is the conductor conductivity; in S / m.

[0142] The conductivity of the conductor is related to the coil material and the operating temperature. The conductivity of a specific material can be obtained from literature. In Equation (21), the cross-sectional area of the conductor is relatively easy to calculate, but the conductor length is relatively difficult to calculate. To find the resistance of the winding, the conductor coil filling factor K is introduced. t , K t is equal to the ratio of the conductor volume V z to the coil volume V x . The conductor volume is equal to the product of the conductor length and the conductor cross-sectional area, and the coil volume is equal to the volume of the space occupied by the entire coil. Through the equivalent relationship transmitted by the coefficient K t , the winding resistance can be transformed into a function of the coil volume V x that is relatively easy to solve:

[0143]

[0144] The coil volume is equal to:

[0145] V x = r w [(2u l + 2u d )r d + πr d 2 (23)

[0146] The filling factor K t can also be expressed as the ratio of the total cross-sectional area of the wire A z = N a and the cross-sectional area of the coil Ax = r w r d , obtaining another expression for K t :

[0147]

[0148] Substituting Equation (23) and Equation (24) into Equation (22), the expression for the resistance of the winding coil is obtained as:

[0149]

[0150] Step 4: Electromagnetic force calculation method based on magnetic field energy. Obtain the electromagnetic adsorption force of the wall-climbing robot according to the first expression and the second expression.

[0151] The research on the electromagnetic adsorption system of the intelligent wall-climbing robot mainly aims to find a calculation method for the electromagnetic adsorption force. Based on the equivalent magnetic circuit analysis, an electromagnetic force calculation method based on magnetic field energy is adopted to derive the energy storage expressions of each part in the electromagnetic system, which can make the calculation of the electromagnetic adsorption force relatively simple. The magnetic energy W f, a part is used to supply the electrical energy W required for the operation of the equivalent magnetic circuit d , a part is converted into the mechanical energy W required for the electromagnetic adsorption force j , assuming that there are no other losses in the coupled field of electrical energy storage and mechanical energy storage, the magnetic energy expression can be written as:

[0152] W f = W d + W j (26)

[0153] According to the analyzed results and Equation (11), it can be known that the electromotive force e of the electrical system is equal to the rate of change of the winding magnetic flux with respect to time. Then, within the time from t0 to t1, the electrical system energy W input into the coupled field through the winding coil d can be expressed as:

[0154]

[0155] where: λ0 and λ1 represent the values of the magnetic flux at times t0 and t1 respectively.

[0156] In the calculation of the mechanical system energy storage, use F j to represent the electromagnetic adsorption force. For the convenience of calculation, introduce the distance variable x to represent the displacement. The mechanical energy required for the electromagnetic force can be expressed as the integral of the force F j with respect to the distance x:

[0157]

[0158] where: x0 and x1 represent the displacements at times t0 and t1 respectively.

[0159] The mechanical energy used to generate the adsorption force is a consumption work for the electromagnetic system and needs to be deducted from the input work of the electrical system. Therefore, when substituting into the total energy storage formula of the equivalent magnetic circuit coupled field, a negative sign should be added before the mechanical system energy storage. Substitute Equation (27) and Equation (28) into Equation (26) to get:

[0160]

[0161] Take the total derivative of Equation (29). According to the basic principle of calculus, it can be obtained:

[0162] dW f = Idλ - F j dx (30)

[0163] In the equivalent magnetic circuit, the resistance of a lumped magnetic circuit unit represents a branch. The resistances of each branch are different, and the magnetic flux densities passing through each branch are also different. If the coil is considered as a whole, then the single-turn coils that make up the coil can be regarded as being able to be allocated to different branches for the calculation of the branch magnetic flux. The magnetic flux of the equivalent magnetic circuit can be expressed as:

[0164] λ = N λ Φ B (31)

[0165] N λ = [N λ,1 , N λ,2 , N λ,3 , ··· N λ,Nb and Ф B = [Ф b,1 , Ф b,2 , Ф b,3 ··· Ф b,Nb represent the flux linkage vector and the magnetic flux density vector of the equivalent magnetic circuit respectively. The number of vector members is determined by the number of branches. Substituting Equation (31) into Equation (30) gives the first expression for the differential of magnetic energy:

[0166] dW f = IN λ dΦ B - F j dx (32)

[0167] Now consider another possible expression for the differential of magnetic energy. Assume that in a single-resistor branch, the branch voltage applied across the resistor is v b , and the current flowing into the resistor is i b . Then, the magnetic energy W f,b flowing into this branch between times t0 and t1 is:

[0168]

[0169] For the sake of convenient derivation, assume that the number of turns of the coil assigned to this branch is 1 turn. According to the magnetomotive force source and the flux linkage theorem, the magnetomotive force source of the branch is numerically equal to the current flowing into the branch, and the branch voltage across the resistor is equal to the rate of change of the branch magnetic flux with time. The above equation can be transformed into:

[0170]

[0171] where: Ф b,0 and Ф b,1 represent the branch magnetic fluxes at times t0 and t1 respectively.

[0172] The above equation only represents the energy storage of one branch. Then, the energy storage of the entire equivalent magnetic circuit can be expressed as:

[0173]

[0174] Among the energy storages of all branches, some are independent of mechanical displacement, and some are related to mechanical displacement. In the branch magnetic flux vector Ф BIn this, the magnetic fluxes of these two branch paths are separated and defined as magnetic flux vectors Ф d and Ф j . In the branch paths related to mechanical displacement, such as the branch paths where the magnetic flux path passes through the gap, the branch magnetic resistance is a function of the displacement quantity x, rather than the magnetic flux Ф b ∈Ф j . According to Equation (8), the magnetomotive force sources of these branch paths are:

[0175] F b =R b(x) Φ b (36)

[0176] Substituting Equation (36) and the vector Ф j into Equation (35) can obtain the expression for the total energy storage of the branch paths related to mechanical displacement:

[0177]

[0178] Taking the derivative of the above equation, we can get:

[0179]

[0180] The total energy storage of the branch paths independent of mechanical displacement does not involve the displacement variable x, so dx can be not considered in the calculation, and we can get:

[0181]

[0182] Combining Equation (38) and Equation (39) to obtain the second expression for the differential of magnetic energy:

[0183]

[0184] So far, two expressions for the differential of magnetic energy have been obtained, then there is:

[0185]

[0186] Equation (41) is an equation about the branch magnetic flux and the displacement variable. According to Kirchhoff's law, the sum of the magnetic fluxes flowing into the node is zero. Let all dФ b in the equation be zero, and simplifying the formula can obtain the expression for the electromagnetic adsorption force:

[0187]

[0188] In the equivalent magnetic circuit, only the magnetic flux path of the gap magnetic resistance passes through the gap, indicating that the energy storage of this branch path is related to mechanical displacement and has nothing to do with the magnetic flux passing through it. Substituting the parameters of this branch path into Equation (42), the expression for the electromagnetic adsorption force of the equivalent magnetic circuit is:

[0189]

[0190] The magnetic resistance calculation formula for the total magnetic resistance of the gap considering the fringe flux has been derived in the previous analysis. According to Equation (20), we have:

[0191]

[0192] Then, according to the derived formulas in Equations (7), (17) to (19), we have:

[0193]

[0194] According to the model parameters set in the previous section, substitute the parameter values into the electromagnetic adsorption force formula for numerical simulation calculation. It should be noted that although the calculation of the branch magnetic resistance in the formula only targets the total magnetic resistance of the protective layer gap considering the fringe flux, the branch magnetic resistances of other branches in the equivalent magnetic circuit that do not participate in mechanical displacement will participate in the calculation of the magnetomotive force source of the entire closed loop, thereby affecting the total magnetic flux of the equivalent magnetic circuit and the distribution of branch magnetic fluxes. Therefore, in the numerical simulation calculation, the magnetic resistance values of this part cannot be ignored to prevent calculation errors.

[0195] Continuously increase the current in the winding coil. With the total magnetic resistance value of the equivalent magnetic circuit remaining unchanged, the total magnetic flux of the closed loop continuously increases, and the magnetic flux vector of the mechanical displacement branch also continuously increases. In the figure, the electromagnetic adsorption force of the system shows a relatively smooth linear curve distribution with the passing current, and the magnitude is between 0 and 150 N. For a single electromagnet, it can meet the system requirements. The magnetic flux of each branch of the protective layer gap is a function of the magnetic induction intensity and the magnetic flux passing area. Assuming that the magnetic induction intensity and the gap magnetic resistance value are constant, the electromagnetic adsorption force will be affected by the effective mapping area between the electromagnet and the steel bar model. According to the parameter setting of the equivalent magnetic circuit, the effective mapping area is between 0 and 0.00125 m 2 Between them, in the figure, as the effective adsorption area increases, the electromagnetic adsorption force of the system also shows a linear upward trend. From the above analysis, the main factors affecting the magnitude of the electromagnetic adsorption force of the system are the magnitude of the current passing through the winding coil under the working state and the effective mapping area between the end face of the electromagnet and the steel bar model.

[0196] Based on the same inventive concept, the present invention also provides a device for calculating the electromagnetic adsorption force of a wall-climbing robot, including an establishment module, an introduction module, and a calculation module.

[0197] The establishment module is used to establish an electromagnetic adsorption equivalent magnetic circuit model between the steel bars on the inner wall of the shaft and the electromagnets inside the wall-climbing robot, establish the relationship between the total magnetic resistance of the magnetic circuit, the current, the number of turns of the winding coil, and the magnetic flux according to the electromagnetic adsorption equivalent magnetic circuit model, and obtain a first expression.

[0198] The introduction module is used to introduce inductance into the electromagnetic adsorption equivalent magnetic circuit model, establish the relationship between winding voltage, current, magnetic flux, magnetic resistance and the rate of change with time, and obtain the second expression.

[0199] The calculation module is used to calculate the electromagnetic adsorption force of the wall-climbing robot according to the first expression and the second expression based on the electromagnetic force calculation method of magnetic field energy.

[0200] The present invention also provides a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the above-mentioned method for calculating the electromagnetic adsorption force of the wall-climbing robot is implemented.

[0201] The present invention also provides a computer-readable storage medium, storing a computer program, which when executed by a processor, implements the above-mentioned method for calculating the electromagnetic adsorption force of the wall-climbing robot.

[0202] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0203] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims

1. A method for calculating the electromagnetic adsorption force of a wall - climbing robot, characterized in that, The wall - climbing robot is used for inspection of the wellbore. The method includes the following steps: Establish an equivalent magnetic circuit model of electromagnetic adsorption between the steel bars on the inner wall of the wellbore and the internal electromagnets of the wall - climbing robot. According to the equivalent magnetic circuit model of electromagnetic adsorption, establish the relationship between the total magnetic resistance of the magnetic circuit, current, the number of turns of the winding coil, and magnetic flux to obtain the first expression; Introduce inductance into the equivalent magnetic circuit model of electromagnetic adsorption, and establish the relationship between winding voltage, current, magnetic flux, magnetic resistance, and the rate of change with time to obtain the second expression; Based on the calculation method of electromagnetic force using magnetic field energy, obtain the electromagnetic adsorption force of the wall - climbing robot according to the first expression and the second expression; The above - mentioned calculation method of electromagnetic force using magnetic field energy, obtaining the electromagnetic adsorption force of the wall - climbing robot according to the first expression and the second expression, includes the following steps: According to the second expression, obtain that the system electromotive force is equal to the rate of change of winding magnetic flux with time. Multiply the rate of change of winding magnetic flux with time by the system current and perform integration to obtain the electrical energy expression; Integrate after introducing the distance variable to the electromagnetic adsorption force to obtain the mechanical energy expression; Add the electrical energy expression and the mechanical energy expression to obtain the magnetic energy expression; Take the derivative of the magnetic energy expression to obtain the first expression of magnetic energy differential; In a single - resistor branch, represent the magnetomotive force source and magnetic flux according to the energy storage expressions of all branches; Based on the first expression, obtain the magnetomotive force source of the branch related to mechanical displacement, and combine the energy storage expressions of all branches to obtain the total energy storage expression of the branch related to mechanical displacement; Take the derivative and transformation of the total energy storage expression of the branch related to mechanical displacement to obtain the second expression of magnetic energy differential; According to Kirchhoff's law, simplify the first expression and the second expression of magnetic energy differential, and substitute the third expression to obtain the expression of electromagnetic adsorption force.

2. The electromagnetic adsorption force calculation method of a wall-climbing robot according to claim 1, characterized in that, Establish an equivalent magnetic circuit model of electromagnetic adsorption between the steel bars on the inner wall of the wellbore and the internal electromagnets of the wall - climbing robot, including the following steps: Apply an electromagnet outside the steel bar to obtain a magnetic circuit system; Divide the overall magnetic circuit nodes according to the structural characteristics of the components in the magnetic circuit system to obtain multiple magnetic circuit units; Use the magnetic resistance of each magnetic circuit unit to represent the magnetomotive force source of the magnetic circuit node, and establish an equivalent magnetic circuit model of electromagnetic adsorption.

3. The electromagnetic adsorption force calculation method of a wall-climbing robot according to claim 2, characterized in that The first expression is as follows: ； In the formula, F is the total magnetomotive force source, N is the number of turns of the winding coil, I is the system current, R t is the magnetic resistance of the steel bar material, R ud is the magnetic resistance at both ends of the electromagnet, R uw is the magnetic resistance of the iron core at the bottom of the electromagnet, R g is the magnetic resistance of the gap in the concrete, Ф is the magnetic flux, R z is the total magnetic resistance.

4. The electromagnetic adsorption force calculation method of a wall - climbing robot according to claim 3, characterized in that, Introduce inductance into the equivalent magnetic circuit model of electromagnetic adsorption, and establish the relationship between winding voltage, current, magnetic flux, magnetic resistance, and the rate of change with time, including the following steps: Introduce inductance into the equivalent magnetic circuit model of electromagnetic adsorption to obtain the relationship between the magnetic flux and current of the winding; According to the above - mentioned relationship and Faraday's law, obtain the second expression; The second expression is as follows: ； In the formula, U is the system voltage, R r is the winding resistance, λ is the winding magnetic flux linkage, t is the time variable.

5. The electromagnetic adsorption force calculation method of a wall-climbing robot according to claim 4, characterized in that, Before obtaining the electromagnetic adsorption force of the wall - climbing robot according to the first expression and the second expression, it is also necessary to introduce fringe magnetic flux into the equivalent magnetic circuit model of electromagnetic adsorption, and correct the gap magnetic resistance of the concrete in the first expression to obtain the third expression, including the following steps: Divide the gap magnetic resistance into outer - corner fringe magnetic resistance, inner - corner fringe magnetic resistance, front - edge magnetic resistance, and rear - edge magnetic resistance; Obtain the magnetic field intensity of the outer - corner fringe magnetic flux according to the magnetic potential drop formula, and obtain the outer - corner fringe magnetic flux expression according to the magnetic flux definition; Substitute the magnetic field intensity of the outer corner edge magnetic flux and the area of the outer corner node into the outer corner edge magnetic flux expression to obtain the outer corner edge magnetic resistance; Based on the outer corner edge magnetic resistance and the length values of the nodes of the inner corner, front edge, and rear edge, obtain the inner corner edge magnetic resistance, front edge magnetic resistance, and rear edge magnetic resistance; Add the gap magnetic resistance to the outer corner edge magnetic resistance, inner corner edge magnetic resistance, front edge magnetic resistance, and rear edge magnetic resistance to obtain a new gap magnetic resistance; The third expression is as follows: ； Wherein, R gz is the new gap reluctance, R bw is the outer corner edge reluctance, R bn is the inner corner edge reluctance, R bq is the front edge reluctance.

6. The electromagnetic adsorption force calculation method of a wall - climbing robot according to claim 5, characterized in that, The expression of the electromagnetic adsorption force is as follows: ； In the formula, F j is the electromagnetic adsorption force, x is the variable gap distance, b is the branch, R b is the branch magnetic resistance, Ф b is the branch magnetic flux, F b is the branch magnetomotive force source, B j is the set of branch magnetic fluxes related to mechanical displacement.

7. An electromagnetic adsorption force calculation device for a wall-climbing robot, characterized in that, including: A building module, configured to establish an electromagnetic adsorption equivalent magnetic circuit model between the reinforcement bars on the inner wall of the wellbore and the internal electromagnets of the wall-climbing robot, establish the relationship between the total magnetic resistance, current, number of turns of the winding coil, and magnetic flux of the magnetic circuit according to the electromagnetic adsorption equivalent magnetic circuit model, and obtain the first expression; An introduction module, configured to introduce inductance into the electromagnetic adsorption equivalent magnetic circuit model, establish the relationship between the winding voltage, current, magnetic flux, magnetic resistance, and time change rate, and obtain the second expression; A calculation module, configured to calculate the electromagnetic adsorption force of the wall-climbing robot based on the electromagnetic force calculation method of magnetic field energy according to the first expression and the second expression; The electromagnetic force calculation method based on magnetic field energy, obtaining the electromagnetic adsorption force of the wall-climbing robot according to the first expression and the second expression, includes the following steps: According to the second expression, obtain that the system electromotive force is equal to the change rate of the winding magnetic chain with respect to time, multiply the change rate of the winding magnetic chain with respect to time by the system current and perform integration to obtain the electrical energy expression; Integrate the electromagnetic adsorption force after introducing the distance variable to obtain the mechanical energy expression; Add the electrical energy expression and the mechanical energy expression to obtain the magnetic energy expression; Derive the magnetic energy expression to obtain the first expression of the magnetic energy differential; In a single-resistance branch, represent it according to the magnetomotive force source and the energy storage expressions of all branches of the magnetic chain; Based on the first expression, obtain the magnetomotive force source of the branch related to the mechanical displacement, and combine the energy storage expressions of all branches to obtain the total energy storage expression of the branch related to the mechanical displacement; Derive and transform the total energy storage expression of the branch related to the mechanical displacement to obtain the second expression of the magnetic energy differential; According to Kirchhoff's law, simplify the first expression and the second expression of the magnetic energy differential, and substitute the third expression to obtain the expression of the electromagnetic adsorption force.

8. A computer device, characterized in that, It includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it implements the electromagnetic adsorption force calculation method of the wall-climbing robot according to any one of claims 1-6 above.

9. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, and when the computer program is executed by the processor, it implements the electromagnetic adsorption force calculation method of the wall-climbing robot according to any one of claims 1-6 above.

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