Digital twinning-based brake shoe temperature change rapid calculation method and system

Abstract

The invention discloses a digital twinning-based brake shoe temperature change rapid calculation method and system. The method comprises the steps of obtaining real-time brake shoe side surface temperature data and historical brake shoe side surface temperature data; inputting the historical brake shoe side surface temperature data into a constructed discretized brake shoe heat conduction model; calculating the influence of the temperature on the contact surface on the temperature of the side surface through heat conduction by using a discretized brake shoe heat conduction model; simulation is carried out according to side surface temperature data in historical data, the contact surface temperature is obtained through calculation, and a temperature mapping matrix K is calculated; when the minimization objective function E (K) is solved, the corresponding optimal temperature mapping matrix K is obtained. And the obtained optimal temperature mapping matrix K is used for reverse solution, and the contact surface temperature of the brake shoe in the digital twin corresponding to the brake shoe side surface temperature data collected in real time is calculated. A digital twinning technology is adopted, a temperature change result is derived by measuring a small amount of data through an indirect sensor, and mapping of the temperature state of the traction machine brake shoe is achieved by using a discretized brake shoe heat conduction model.

Description

Technical Field

[0001] The present invention relates to the technical field of elevator digital twins, and in particular to a method and system for quickly calculating the temperature change of a brake shoe based on digital twins. Background Art

[0002] With the rapid development of my country's economic construction and the rapid construction of high-rise buildings, elevators have become an indispensable facility in people's daily production and life. Digital twin technology integrates multi-physics, multi-disciplines, and multi-scales, and has the characteristics of hyper-realism, real-time synchronization, full elements, and uniqueness. It can realize the interactive integration of the physical world and the information world, thereby reflecting the full life cycle process of the corresponding physical equipment. Therefore, by effectively integrating digital twins with key elevator components, the reliability, accuracy, and safety of elevators can be improved during their full life cycle operation; the current technical difficulties in installing sensors on brake shoes are high installation costs and the inability to fully cover local areas. Digital twin technology provides the ability to map the virtual and real aspects of brakes, but how to efficiently use limited measurement data to derive global results is the current technical bottleneck.

[0003] This paper conducts specific research on the brake shoe, a key component of the elevator. At present, the health monitoring of the brake shoe relies on offline experimental data or highly complex finite element simulation, which makes it difficult to achieve real-time calculation and global temperature change field calculation. Therefore, it is necessary to propose a fast temperature change calculation method, which can derive the global temperature change results by measuring a small amount of data with indirect sensors, thereby constructing a fast temperature change calculation model to achieve the mapping relationship of the health status of the traction machine brake shoe. Summary of the invention

[0004] Therefore, the purpose of the present invention is to provide a fast calculation method for the temperature change of brake shoes based on digital twins. The digital twin technology is adopted to derive the temperature change results by measuring a small amount of data through indirect sensors, and a discretized brake shoe heat conduction model is constructed to realize the mapping of the temperature state of the traction machine brake shoe.

[0005] In order to achieve the above object, a method for quickly calculating the temperature change of a brake shoe based on digital twin of the present invention comprises the following steps: Obtain real-time brake shoe side temperature data and historical brake shoe side temperature data; Inputting the historical brake shoe side temperature data into the constructed discretized brake shoe heat conduction model; using the discretized brake shoe heat conduction model, calculating how the temperature on the contact surface affects the temperature on the side through heat conduction; Simulate the side temperature data in the historical data, calculate the contact surface temperature, and calculate the temperature mapping matrix ; Solve to minimize the objective function When the corresponding optimal temperature mapping matrix .

[0006] The optimal temperature mapping matrix obtained Reverse solution is performed to calculate the contact surface temperature of the brake shoe in the digital twin corresponding to the real-time collected brake shoe side temperature data.

[0007] Further preferably, the construction of the discretized brake shoe heat conduction model includes constructing a discrete contact model of the brake shoe according to the following steps: The contact area of ​​the brake shoe is defined as a two-dimensional rectangular area, and the mesh discretization size is ( , ), is the brake shoe length, is the brake shoe thickness; Discretize the contact surface of the brake shoe and divide it into points; then, the grid step size is , ; Further preferably, based on the brake shoe discrete contact model, a brake shoe heat conduction model is constructed according to the heat conduction characteristics of the brake shoe; definition For the grid The temperature of the point; starting from the contact surface, when the heat diffuses along the contact surface, the following two-dimensional heat conduction equation is satisfied: in: are the density, specific heat capacity and thermal conductivity of the material respectively; Heat generated by friction, depends on the friction force and relative sliding speed ; is the spatial diffusion term of the temperature on the contact surface; Will The partial differential equation is discretized to obtain the discrete equation for each grid point on the contact surface; The heat conduction model of the brake shoe is constructed according to the explicit finite difference method: .

[0008] Further preferably, When discretizing the partial differential equation, the following steps are taken: First, the time derivative of the brake shoe temperature is discretized: ;in: To indicate the At time steps, the grid points Temperature; is the time step.

[0009] Secondly, the spatial derivative of the brake shoe temperature is discretized and the spatial derivative is and Perform central difference: ; ; in: For the At time steps, the grid points and Temperature; Further preferably, the construction of the brake shoe heat conduction model according to the explicit finite difference method includes: The contact surface of the brake shoe is simplified into a two-dimensional rectangular area, and the brake shoe temperature is updated through the discretized heat conduction equation. The discrete forms of the time derivative and space derivative are substituted into the heat conduction equation based on the explicit finite difference method: For rectangular areas: The brake shoe contact surface temperature is defined as , the temperature distribution is ; Brake shoe side temperature is defined as , the temperature distribution is .

[0010] Further preferably, the simulation is performed based on the side temperature data in the historical data to calculate the contact surface temperature and calculate the temperature mapping matrix The process includes the following steps: S301, initializing the temperature field, setting the initial contact surface temperature and the side surface temperature; S302, using an explicit finite difference method to iteratively calculate how the temperature on the contact surface affects the temperature of the side surface through heat conduction; S303, establishing a mapping matrix according to the simulation results , ;in are the vectorized forms of the side and contact surface temperatures, respectively; for The matrix represents the contact surface temperature matrix, which represents the temperature values ​​of each grid point on the contact surface in all simulations: , each column is the contact surface temperature vector obtained from the i-th simulation; the side temperature matrix for , which represents the temperature values ​​of each grid point on the side in all simulations: , each column is the side temperature vector obtained from the i-th simulation.

[0011] S304, by minimizing the error objective function , find the optimal mapping matrix .

[0012] Further preferably, in S304, the error objective function is minimized. , find the optimal mapping matrix , using the following steps: Using the objective function Characterizes the error between the side temperature of the model and the actual side temperature; Will right Take the derivative and set it equal to 0, that is: After simplification, we get: .

[0013] The present invention also provides a brake shoe temperature change rapid calculation system based on digital twin, which performs brake shoe temperature change rapid calculation in the digital twin brake based on the above-mentioned brake shoe temperature change rapid calculation method based on digital twin; comprising: A data acquisition module, which acquires real-time brake shoe side temperature data and historical brake shoe side temperature data; A discretized brake shoe heat conduction model is used to input the historical brake shoe side temperature data; using the discretized brake shoe heat conduction model, calculate how the temperature on the contact surface affects the temperature of the side through heat conduction; The simulation module simulates the side temperature data in the historical data, calculates the contact surface temperature, and calculates the temperature mapping matrix ; Solve to minimize the objective function When the corresponding optimal temperature mapping matrix .

[0014] Contact surface temperature calculation module, using the optimal temperature mapping matrix Reverse solution is performed to calculate the contact surface temperature of the brake shoe in the digital twin corresponding to the real-time collected brake shoe side temperature data.

[0015] The present invention also provides an electronic device, comprising: a memory storing computer program instructions; A processor, when the computer program instructions are executed by the processor, implements the steps of the above-mentioned method for rapid calculation of brake shoe temperature change based on digital twin.

[0016] The present invention also provides a computer-readable storage medium, which is used to store instructions. When the stored instructions are run on a computer, the computer executes the steps of the above-mentioned method for rapid calculation of brake shoe temperature change based on digital twins.

[0017] The digital twin-based brake shoe temperature change rapid calculation method and system disclosed in the present application derives the global temperature change results by measuring a small amount of data through indirect sensors, thereby constructing a rapid temperature change calculation model to achieve a mapping relationship of the health status of the traction machine brake shoe.

[0018] The present invention combines historical and real-time data, uses a discretized brake shoe heat conduction model and an optimization method that minimizes the objective function to achieve accurate inverse calculation of the contact surface temperature. Through the optimization of the temperature mapping matrix, the temperature changes under different working conditions can be quickly calculated, which significantly improves the accuracy and calculation efficiency of temperature prediction and avoids the high cost and low efficiency problems of traditional methods. The system can adapt to complex working condition changes and accurately reflect the temperature state of the brake shoe.

[0019] Secondly, the digital twin technology was used to establish a brake shoe model in a virtual environment. By collecting a small amount of data through sensors, the contact surface temperature was derived by combining the digital twin model and calculation method, which reduced the number of sensors, hardware costs and installation difficulties. By eliminating the need to arrange multiple sensors on the contact surface, the system not only simplifies maintenance work, but also greatly improves the reliability of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a flow chart of the method for quickly calculating the temperature change of brake shoes based on digital twins of the present invention. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below through the accompanying drawings and specific embodiments.

[0022] Because the contact surface of the brake shoe and the contact surface of the brake wheel are completely fitted, the brake shoe component cannot be directly equipped with sensors for monitoring. Considering that the friction between the brake shoe and the brake wheel during the braking process will generate heat, causing the local temperature of the brake shoe to rise. Therefore, this application uses an indirect stress inversion method based on machine vision to monitor the temperature distribution on the side of the brake shoe in real time.

[0023] like Figure 1 As shown, a method for quickly calculating brake shoe temperature change based on digital twins provided by an embodiment of one aspect of the present invention comprises the following steps: S1. Obtain real-time brake shoe side temperature data and historical brake shoe side temperature data; first monitor the brake shoe temperature field, install a high-resolution online thermal imaging camera on the side of the traction machine brake shoe, and the acquisition range is -20℃~650℃; based on the infrared imaging method, the brake shoe side temperature distribution is monitored in real time.

[0024] First, collect the temperature data values ​​of multiple key points on the side of the brake shoe , analyze the temperature change rate with braking time , thereby mapping the temperature data to the temperature change distribution of the contact surface.

[0025] S2, inputting the historical brake shoe side temperature data into the constructed discretized brake shoe heat conduction model; using the discretized brake shoe heat conduction model, calculating how the temperature on the contact surface affects the temperature of the side through heat conduction; When the discretized brake shoe heat conduction model is constructed, a brake shoe contact model is constructed based on the collected real-time dynamic data of the brake shoe and surrounding related components. The brake shoe contact model includes constructing a discrete contact model of the brake shoe according to the contact characteristics of the brake shoe, and constructing a brake shoe heat conduction model according to the heat conduction characteristics of the brake shoe. When constructing the discrete contact model of the brake shoe, the geometric characteristics of the brake shoe must be defined first: that is, the contact area of ​​the brake shoe is defined as a two-dimensional rectangular area (the contact surface is ), the grid discretization size is: is the brake shoe length (along the x direction); is the brake shoe thickness (along the y direction); Then the contact surface of the brake shoe is discretized and divided into points; then, the grid step size is , ; When establishing the heat conduction model of the brake shoe, first define For the grid The temperature of the point; On the contact surface between the brake shoe and the brake wheel, the friction between the two is the main heat source, and the heat diffuses along the contact surface, satisfying the two-dimensional heat conduction equation: in: is the spatial diffusion term of the temperature on the contact surface; Heat generated by friction, depends on the friction force and relative sliding speed ; are the density, specific heat capacity and thermal conductivity of the material respectively.

[0026] Will The partial differential equation is discretized to obtain the discrete equation for each grid point on the contact surface; The specific discretization process is as follows: First, the time derivative of the brake shoe temperature is discretized: in: To indicate the At time steps, the grid points Temperature; is the time step.

[0027] 2. Secondly, the spatial derivative of the brake shoe temperature is discretized and the spatial derivative is and Perform central difference: ; .

[0028] in: When it is the nth time step, the grid point and Temperature; The discrete heat conduction equation is formulated according to the explicit finite difference method: The heat diffusion term describes the heat transfer of the brake shoe along the The diffusion in the direction is determined by the temperature of the surrounding grid points and the thermal conductivity of the material 𝑘; the heat source term describes the phenomenon of local temperature increase caused by contact friction or other heat sources of the brake shoe.

[0029] The contact surface of the brake shoe is simplified into a two-dimensional rectangular area. The update of the brake shoe temperature is realized by discretizing the heat conduction equation. The discrete forms of the time derivative and the space derivative are substituted into the heat conduction equation based on the explicit finite difference method:

[0030] For rectangular areas: The brake shoe contact surface temperature is defined as , the temperature distribution is ; Brake shoe side temperature is defined as , the temperature distribution is .

[0031] S3. Simulate the side temperature data in the historical data, calculate the contact surface temperature, and calculate the temperature mapping matrix ; Mapping relationship of brake shoe: Since the conduction of heat in the brake shoe is a diffusion process, the heat on the contact surface will be transferred to the side along the material. Using the discretized heat conduction equation, the mapping matrix can be generated by simulating the temperature change of the contact surface. , expressing the influence of contact surface temperature to side surface temperature: Mapping Matrix is a The matrix of is the number of side mesh points, is the number of contact surface grid points; the matrix Each row of corresponds to the temperature of the side surface grid point, and each column corresponds to the influence of the temperature of the contact surface grid point on the side surface temperature.

[0032] By recursively extrapolating the heat conduction equation to the grid points, the process of heat conduction from the contact surface to the side surface can be described to gradually update the temperature field of the entire area.

[0033] To infer the side surface temperature from the contact surface temperature obtained through multiple simulations, it is necessary to calculate the effect of the contact surface temperature on the side surface temperature through numerical simulation or analytical methods. This can be done through the following steps: The first step is to initialize the temperature field and set the initial contact surface temperature and side surface temperature; The second step is to calculate the heat conduction. The explicit finite difference method is used to iteratively calculate the temperature on the contact surface and how it affects the temperature on the side surface through heat conduction.

[0034] The third step is to build a mapping relationship: establish a mapping matrix based on the simulation results , ; in are the vectorized forms of the side and contact surface temperatures, respectively.

[0035] Set N simulations, each simulation solution has a contact surface temperature field and a side surface temperature field. Specifically: Contact surface temperature matrix is a The matrix represents the temperature values ​​of each grid point on the contact surface in all simulations: , each column is the contact surface temperature vector obtained from the i-th simulation.

[0036] Side Temperature Matrix is a , which represents the temperature values ​​of each grid point on the side in all simulations: , each column is the side temperature vector obtained from the i-th simulation.

[0037] S4. Solve the minimization objective function When the corresponding optimal temperature mapping matrix .

[0038] According to the relationship between the contact surface temperature and the side surface temperature, solve the mapping matrix , , by minimizing the error objective function , find the optimal mapping matrix.

[0039] Objective Function It measures the error between the model's side temperature and the actual side temperature. It can be expressed as: ; To simplify the solution, all simulation results are combined into a matrix form: for ; for The matrix of .

[0040] For this purpose, the objective function can be written as: ,in represents the Frobenius norm (the square root of the sum of the squares of the elements of the matrix), that is:

[0041] Minimize the objective function to minimize ,right Take the derivative and set it to zero:

[0042] After simplification, we get: .

[0043] in: is a The square matrix represents the covariance matrix of the contact surface temperature, and its inverse matrix Used to stabilize the solution of the mapping matrix .

[0044] S5. Optimal temperature mapping matrix Reverse solution is performed to calculate the contact surface temperature of the brake shoe in the digital twin corresponding to the real-time collected brake shoe side temperature data.

[0045] When the side temperature is measured, the contact surface temperature is inferred by the optimization method: that is, the measured value corresponds to the column vector, and the contact surface temperature is inferred. ; in: is a A square matrix, representing the covariance matrix of the mapping matrix; It is its inverse matrix that is used to stably reversely deduce the contact surface temperature; It is to combine the side temperature data with the relationship of the mapping matrix to obtain the optimal solution of the contact surface temperature.

[0046] The present invention also provides a brake shoe temperature change rapid calculation system based on digital twin, which performs brake shoe temperature change rapid calculation in the digital twin brake based on the above-mentioned brake shoe temperature change rapid calculation method based on digital twin; comprising: A data acquisition module, which acquires real-time brake shoe side temperature data and historical brake shoe side temperature data; A discretized brake shoe heat conduction model is used to input the historical brake shoe side temperature data; using the discretized brake shoe heat conduction model, calculate how the temperature on the contact surface affects the temperature of the side through heat conduction; The simulation module simulates the side temperature data in the historical data, calculates the contact surface temperature, and calculates the temperature mapping matrix ; Solve to minimize the objective function When the corresponding optimal temperature mapping matrix .

[0047] Contact surface temperature calculation module, using the optimal temperature mapping matrix Reverse solution is performed to calculate the contact surface temperature of the brake shoe in the digital twin corresponding to the real-time collected brake shoe side temperature data.

[0048] The present invention can be applied to an electronic device, comprising: a memory storing computer program instructions; A processor, when the computer program instructions are executed by the processor, implements the steps of the method for rapid calculation of brake shoe temperature change based on digital twin as described above.

[0049] The present invention also provides a computer-readable storage medium, which is used to store instructions. When the stored instructions are run on a computer, the computer executes the steps of the above-mentioned method for rapid calculation of brake shoe temperature change based on digital twins.

[0050] Obviously, the above embodiments are only examples for clear explanation, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from them are still within the protection scope of the invention.

Claims

1. A fast calculation method for brake shoe temperature change based on digital twin, characterized in that: The following steps are involved: Obtain real-time brake shoe side temperature data and historical brake shoe side temperature data; Inputting the historical brake shoe side temperature data into the constructed discretized brake shoe heat conduction model; using the discretized brake shoe heat conduction model, calculating how the temperature on the contact surface affects the temperature of the side through heat conduction; Simulate the side temperature data in the historical data, calculate the contact surface temperature, and calculate the temperature mapping matrix ; Solve to minimize the objective function When the corresponding optimal temperature mapping matrix ; The optimal temperature mapping matrix obtained Reverse solution is performed to calculate the contact surface temperature of the brake shoe in the digital twin corresponding to the real-time collected brake shoe side temperature data.

2. The method for rapid calculation of brake shoe temperature change based on digital twin according to claim 1 is characterized in that: The construction of the discretized brake shoe heat conduction model includes constructing a discrete contact model of the brake shoe according to the following steps: The contact area of ​​the brake shoe is defined as a two-dimensional rectangular area, and the mesh discretization size is ( , ), is the brake shoe length, is the brake shoe thickness; Discretize the contact surface of the brake shoe and divide it into points; then, the grid step size is , .

3. The method for rapid calculation of brake shoe temperature change based on digital twin according to claim 2 is characterized in that: Based on the brake shoe discrete contact model, a brake shoe heat conduction model is constructed according to the heat conduction characteristics of the brake shoe; definition For the grid The temperature of the point; starting from the contact surface, when the heat diffuses along the contact surface, the following two-dimensional heat conduction equation is satisfied: in: are the density, specific heat capacity and thermal conductivity of the material respectively; Heat generated by friction, depends on the friction force and relative sliding speed ; is the spatial diffusion term of the temperature on the contact surface; Will The partial differential equation is discretized to obtain the discrete equation for each grid point on the contact surface; The heat conduction model of the brake shoe is constructed according to the explicit finite difference method: .

4. The method for rapid calculation of brake shoe temperature change based on digital twin according to claim 3 is characterized in that: In the When discretizing the partial differential equation, the following steps are taken: First, the time derivative of the brake shoe temperature is discretized: ;in: To indicate the At time steps, the grid points Temperature; is the time step; Secondly, the spatial derivative of the brake shoe temperature is discretized and the spatial derivative is and Perform central difference: ； ； in: , For the At time steps, the grid points and temperature.

5. The method for rapid calculation of brake shoe temperature change based on digital twin according to claim 3 is characterized in that: The heat conduction model of the brake shoe is constructed according to the explicit finite difference method, including: The contact surface of the brake shoe is simplified into a two-dimensional rectangular area, and the brake shoe temperature is updated through the discretized heat conduction equation. The discrete forms of the time derivative and space derivative are substituted into the heat conduction equation based on the explicit finite difference method: For rectangular areas: The brake shoe contact surface temperature is defined as , the temperature distribution is ; Brake shoe side temperature is defined as , the temperature distribution is .

6. The method for rapid calculation of brake shoe temperature change based on digital twin according to any one of claims 1 to 5, characterized in that: The simulation is performed based on the side temperature data in the historical data to calculate the contact surface temperature and calculate the temperature mapping matrix The following steps are included: S301, initializing the temperature field, setting the initial contact surface temperature and the side surface temperature; S302, using an explicit finite difference method to iteratively calculate how the temperature on the contact surface affects the temperature on the side surface through heat conduction; S303, establishing a mapping matrix according to the simulation results , ;in , are the vectorized forms of the side and contact surface temperatures, respectively; for The matrix represents the contact surface temperature matrix, which represents the temperature values ​​of each grid point on the contact surface in all simulations: , each column is the contact surface temperature vector obtained from the i-th simulation; the side temperature matrix for , which represents the temperature values ​​of each grid point on the side in all simulations: , each column is the side temperature vector obtained from the i-th simulation; S304, by minimizing the error objective function , find the optimal mapping matrix .

7. The method for rapid calculation of brake shoe temperature change based on digital twin according to claim 6 is characterized in that: In S304, the error objective function is minimized. , find the optimal mapping matrix , using the following steps: Using the objective function Characterizes the error between the side temperature of the model and the actual side temperature; Will right Take the derivative and set it equal to 0, that is: After simplification, we get: .

8. A brake shoe temperature change rapid calculation system based on digital twin, characterized in that: Based on the method for rapid calculation of brake shoe temperature change based on digital twin according to any one of claims 1 to 7 above, rapid calculation of brake shoe temperature change is performed in the digital twin brake; comprising: A data acquisition module, which acquires real-time brake shoe side temperature data and historical brake shoe side temperature data; A discretized brake shoe heat conduction model is used to input the historical brake shoe side temperature data; using the discretized brake shoe heat conduction model, calculate how the temperature on the contact surface affects the temperature of the side through heat conduction; The simulation module simulates the side temperature data in the historical data, calculates the contact surface temperature, and calculates the temperature mapping matrix ; Solve to minimize the objective function When the corresponding optimal temperature mapping matrix ; Contact surface temperature calculation module, using the optimal temperature mapping matrix Reverse solution is performed to calculate the contact surface temperature of the brake shoe in the digital twin corresponding to the real-time collected brake shoe side temperature data.

9. An electronic device, characterized in that: include: a memory storing computer program instructions; A processor, when the computer program instructions are executed by the processor, implements the steps of the method for quickly calculating the temperature change of brake shoes based on digital twins as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium is used to store instructions. When the stored instructions are executed on a computer, the computer executes the steps of the method for rapid calculation of brake shoe temperature change based on digital twin as claimed in any one of claims 1 to 6.

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