A system and method for measuring thermophysical parameters based on heat flux

Abstract

A system and method for measuring thermal properties based on heat flux are disclosed. The system includes a heat flux sensor, a temperature sensor, and a heater. One side of the heat flux sensor contacts the surface of the object being measured, and the heater is positioned on the other side. The heater covers the heat flux sensor on the heat transfer surface of the object being measured. The heat generated by the heater is conducted to the object being measured through the heat flux sensor. The heat flux sensor measures the heat flux density through the boundary of the object being measured. The temperature sensor is positioned on the surface of the object being measured, equivalent to the side of the heat flux sensor that contacts the object, and measures the temperature at the boundary of the object being measured. The measured heat flux density and temperature are used to determine the thermal properties of the object being measured. This invention has advantages such as high accuracy, miniaturization, and good stability, and can accurately and quickly measure the thermal conductivity and thermal diffusivity of different objects.

Description

Technical Field

[0001] This invention relates to the measurement of thermal parameters, and in particular to a system and method for measuring thermal properties based on heat flux. Background Technology

[0002] With the continuous development of technologies such as intelligent sensing, tactile reproduction, and virtual reality, rapid and accurate object recognition has become crucial for enhancing the interaction capabilities of robots and automatic control systems with the outside world. It is also a hot topic in tactile feedback research and is receiving increasing attention. Among these, thermal sensing is an important direction in tactile feedback. Thermal sensors simulate the temperature changes perceived by human skin when in contact with an object, which can be used to identify materials with different thermal conductivity. Currently, various thermal sensing methods exist, such as the constant voltage method, the constant temperature difference method, and the peak heat flux method. These methods measure the characteristic data of temperature and heat after the sensor contacts the object and transmit this data to the terminal for comparison to distinguish different materials, achieving good results. However, these methods can only qualitatively distinguish materials. In fields such as tactile reproduction, richer and more multi-dimensional tactile signals are needed. Besides identifying the type of object, it is also necessary to obtain the object's thermal information. Currently, quantitative methods for measuring the thermal properties of materials often require large instruments or the fabrication of specific structures, lacking flexibility. Therefore, new methods are needed to address this problem.

[0003] It should be noted that the information disclosed in the background section above is only for understanding the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0004] The main objective of this invention is to overcome the deficiencies of the aforementioned background technology and provide a system and method for measuring thermophysical parameters based on heat flux.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A thermal property parameter measurement system based on heat flux includes a heat flux sensor, a temperature sensor, and a heater. One side of the heat flux sensor is in contact with the surface of the object being measured, and the heater is disposed on the other side of the heat flux sensor. The heat transfer surface of the heater covers the heat flux sensor of the object being measured. The heat generated by the heater is conducted to the object being measured through the heat flux sensor. The heat flux sensor is used to measure the heat flux density through the boundary of the object being measured. The temperature sensor is disposed on the surface of the object being measured in a manner equivalent to placing it on the side of the heat flux sensor that is in contact with the object being measured. The temperature sensor is used to measure the temperature of the boundary of the object being measured. The measured heat flux density and temperature are used to determine the thermal property parameters of the object being measured.

[0007] Furthermore:

[0008] The heat flux sensor is a flexible heat flux sensor, and its sensing element is a thermopile.

[0009] The heater covers a larger area than the heat flux sensor covers the object being measured. The temperature sensor is located on the surface of the object being measured, which is within the area covered by the heater but outside the area covered by the heat flux sensor. A thermal resistance layer is provided between the temperature sensor and the heater.

[0010] The heat flux sensor is encapsulated in polyimide, and the thermal resistance layer is a polyimide layer.

[0011] The thermal resistance layer has the same thickness as the heat flux sensor and the same area as the heater. The thermal resistance layer has a hollow structure in the middle for mounting and embedding the heat flux sensor.

[0012] The temperature sensor is a thin-wire thermocouple.

[0013] The heater has a heat insulation structure on the side facing away from the heat flux sensor.

[0014] Based on the measured heat flux density and temperature, the thermal properties of the object under test are determined by constructing a discrete transient heat conduction model, specifically including:

[0015] Treating the object under test as a semi-infinite object, and discretizing it into N unit points perpendicular to the surface, the boundary equation for heat transfer is:

[0016]

[0017] Where T represents temperature, i represents the number of iterations, k is the thermal conductivity of the object being measured, ρ and c are the density and heat capacity of the object being measured, respectively, Δx is the spacing between discretized unit points, Δτ is the time interval between iterations, and q is the heat flux density flowing into the object.

[0018] For nodes 2 to N-1, the governing equations are:

[0019]

[0020] Where α is the thermal diffusivity of the object being measured;

[0021] The initial temperature of the object is T0, and the lower boundary conditions and initial conditions are as follows:

[0022]

[0023]

[0024] Based on the given (e.g., randomly given) thermal conductivity and thermal diffusivity of the object being measured, the theoretical temperature of the object's surface is calculated according to the measured heat flux density.

[0025] An evaluation function is constructed based on the error between the calculated theoretical temperature and the actual measured temperature. Through iterative solution and fitting calculation, the thermal conductivity and thermal diffusivity of the measured object are obtained from the parameters corresponding to the minimum error.

[0026] Using the root mean square error between the calculated theoretical temperature and the actual measured temperature as the evaluation function, the thermal conductivity and thermal diffusivity of the measured object are calculated by least squares fitting.

[0027] A method for measuring thermal property parameters based on heat flux, using the system described above to measure the thermal property parameters of an object.

[0028] The present invention has the following beneficial effects:

[0029] This invention proposes a system and method for measuring thermal properties based on heat flux, which offers advantages such as high accuracy, good stability, miniaturization, and rapid measurement. Different materials have different thermal conductivity, which can be measured by thermal conductivity and thermal diffusivity. Under a given heat flux density, the temperature change of an object is directly related to its thermal conductivity and thermal diffusivity. The measurement system of this invention can be directly attached to the surface of the object being measured. When the heater is powered, the heat flux sensor can measure the heat flux density flowing into the object in real time, while the thermocouple is in direct contact with the object's surface to measure the surface temperature change. Subsequently, based on the measured heat flux density and temperature, the theoretical temperature change can be calculated using a transient heat conduction model. The root mean square error between the measured temperature and the actual temperature is used as an evaluation function. By calculating the parameters corresponding to the minimum error through an optimization algorithm, the thermal conductivity and thermal diffusivity of the object being measured can be obtained.

[0030] The thermal sensing measurement system constructed in this invention has the advantages of high precision, miniaturization, good stability, and easy integration into intelligent robots and control systems. Its measurement results are calculated through the corresponding discrete transient heat conduction model, which can accurately and quickly measure the thermal conductivity and thermal diffusivity of different objects.

[0031] On the one hand, heat flux sensors can directly measure the heat flux density flowing into an object without requiring modeling of the sensor and substrate, greatly simplifying the physical model, reducing the number of variables, and thus improving the model's computational accuracy. On the other hand, the model's input is heat flux density, and it calculates thermal conductivity and thermal diffusivity based on changes in the object's boundary temperature. Within a certain range, the initial temperature of the object being measured has no impact on the system's measurement, meaning there is no need to consider the object's initial temperature, making it highly applicable.

[0032] In the preferred embodiment, the structural parameters of components such as the heat flux sensor, serpentine heater, and thin-film thermal resistance layer can be designed according to different application scenarios. The thermal insulation structure can use different types of materials or be directly applied to actuators such as robotic arms, making the system easy to integrate with automatic control systems. Furthermore, the sensor used in the system is a flexible structure composed of metal and polymer, and the entire structure is encapsulated in polymer, exhibiting high robustness. In summary, the thermal property parameter measurement system and method based on heat flux of this invention can be directly used in execution terminals for contact-based quantitative thermal sensing of target objects, offering advantages such as fast measurement speed, high accuracy, strong robustness, and small size. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the thermal property parameter measurement system based on heat flux according to an embodiment of the present invention;

[0034] Figure 2 This is a cross-sectional schematic diagram of the system in an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of a discrete transient heat conduction model for modeling the target object in an embodiment of the present invention;

[0036] Figure 4 This refers to the heat flux data of aluminum alloy thermal parameters measured by the system in this embodiment of the invention within 2 seconds;

[0037] Figure 5 These are the model calculation and fitting results of the system on aluminum alloy measurement data in this embodiment of the invention;

[0038] Figure 6 This is the heat flux data of tempered glass measured within 2 seconds by the system in this embodiment of the invention.

[0039] Figure 7 This is the model calculation and fitting result of the system on the measurement data of tempered glass in the embodiment of the present invention. Detailed Implementation

[0040] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope and application of the present invention.

[0041] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component. Furthermore, a connection can be used for fixing, coupling, or communication.

[0042] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0043] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0044] To achieve stable and portable measurement of thermal parameters, this invention considers both thermal sensors and thermal conduction models. On one hand, the thermal sensor or system needs to have a thin profile, a sufficiently large heating area, and accurate temperature measurement precision. Such sensors can be fabricated into flexible devices using micro-nano fabrication processes and attached to the surface of the object being measured. On the other hand, the construction of the thermal conduction model needs to consider the geometry of the sensor and the object, as well as the actual application scenario, to solve for the transient process of temperature change over time. While a thermal sensor combined with a thermal conduction model can obtain the thermal parameters of the measured material through algorithms, the sensor's structural design and the number of variables in the model both affect the accuracy of the measurement results. In the thermal sensing measurement system of this invention, the heat flux sensor measures the heat flow through the sensor, and its attachment to the object surface allows for direct measurement of the boundary heat flux density. Simultaneously, by introducing the measurement of the object's boundary temperature and constructing a discrete transient thermal conduction model, portable and accurate measurement of thermal properties can be achieved more effectively.

[0045] See Figure 1 and Figure 2This invention provides a thermal property parameter measurement system based on heat flux, including a heat flux sensor 2, a temperature sensor (such as a thin-wire thermocouple 3), and a heater (such as a serpentine heater 5). One side of the heat flux sensor 2 is in contact with the surface of the object under test 1, and the heater is disposed on the other side of the heat flux sensor 2. The heat transfer surface of the heater covers the heat flux sensor 2 of the object under test 1. The heat generated by the heater is conducted to the object under test 1 through the heat flux sensor 2. The heat flux sensor 2 is used to measure the heat flux density (also called heat flux) through the boundary of the object under test 1. The temperature sensor is disposed on the surface of the object under test 1 in a manner equivalent to placing it on the side of the heat flux sensor 2 that is in contact with the object under test 1. The temperature sensor is used to measure the temperature of the boundary of the object under test 1. The measured heat flux density and temperature can be used to determine the thermal property parameters of the object under test 1, including thermal conductivity and thermal diffusivity, which will be further explained below.

[0046] In a preferred embodiment, the heat flux sensor 2 is a flexible heat flux sensor, and its sensing element is a thermopile.

[0047] In a preferred embodiment, the area covered by the heater to the heat flux sensor 2 is larger than the area covered by the heat flux sensor 2 to the object 1 being measured. The temperature sensor is disposed on the surface of the object 1 being measured, which is within the coverage area of ​​the heater but outside the coverage area of ​​the heat flux sensor 2. Preferably, the temperature sensor can be a thin-wire thermocouple 3. A thermal resistance layer (such as a polyimide thermal resistance layer 4) is disposed between the temperature sensor 3 and the heater 5. The thermal resistance layer serves as the medium for the equivalent heat flux sensor (it can be a material with the same or similar properties as the heat flux sensor medium), thus effectively placing the temperature sensor 3 on the surface of the object 1 being measured on the side where the heat flux sensor 2 contacts the object 1. The temperature sensor can also be disposed between the surface of the heat flux sensor 2 and the object 1 being measured for boundary temperature detection, but this placement can easily affect the heat transfer between the heat flux sensor 2 and the object 1 being measured. The optimized design of this embodiment can achieve accurate detection of the object boundary temperature without affecting the accuracy of the heat flux sensor 2 in detecting the heat flux density at the object boundary. The design of this embodiment is equivalent to simultaneously measuring the heat flux density flowing into the object and the object boundary temperature in a vertical direction. It should be understood that the equivalent designation in this invention also includes placing the temperature sensor directly on the side where the heat flux sensor 2 contacts the object 1 being measured.

[0048] Preferably, the heat flux sensor 2 is a polyimide-encapsulated heat flux sensor, and the thermal resistance layer is a polyimide thermal resistance layer 4.

[0049] In a preferred embodiment, the thickness of the thermal resistance layer is the same as that of the heat flux sensor 2, and the area is the same as that of the heater. The middle of the thermal resistance layer has a hollow structure for mounting and embedding the heat flux sensor 2.

[0050] In a preferred embodiment, the heater is provided with a heat insulation structure (such as a polyurethane heat insulation layer 6) on the side facing away from the heat flux sensor.

[0051] Preferably, the heat flux sensor 2, the temperature sensor, the heater, and the periphery of the thermal insulation structure are all encapsulated by a polymer, such as PDMS encapsulation 7.

[0052] This invention also provides a method for measuring thermal property parameters based on heat flux. Using the aforementioned thermal property parameter measurement system, the thermal conductivity and thermal diffusivity of an object are measured by constructing a discrete transient heat conduction model.

[0053] Different materials have different thermal conductivity, which can be measured by thermal conductivity and thermal diffusivity. At a given heat flux density, the temperature change of an object is directly related to its thermal conductivity and thermal diffusivity. The measurement system of this invention can be directly attached to the surface of the object being measured. When the heater is powered, the heat flux sensor can measure the heat flux density flowing into the object in real time, while the thermocouple is in direct contact with the object's surface to measure the surface temperature change. Then, based on the measured heat flux density and temperature, the theoretical temperature change can be calculated using a transient heat conduction model. The root mean square error between the measured and actual temperatures is used as an evaluation function. By calculating the parameters corresponding to the minimum error using an optimization algorithm, the thermal conductivity and thermal diffusivity of the object being measured can be obtained.

[0054] The thermal sensing measurement system of this invention has the advantages of high accuracy, miniaturization, good stability, and easy integration into intelligent robots and control systems. It calculates the measurement results using a corresponding discrete transient heat conduction model, enabling accurate and rapid measurement of the thermal conductivity and thermal diffusivity of different objects. On one hand, the heat flux sensor can directly measure the heat flux density flowing into the object without modeling the sensor and substrate, greatly simplifying the physical model, reducing the number of variables, and thus improving the model's calculation accuracy. On the other hand, the model's input is heat flux density, and it calculates thermal conductivity and thermal diffusivity based on changes in the object's boundary temperature. Within a certain range, the initial temperature of the measured object has no effect on the system's measurement, meaning that the initial temperature of the object does not need to be considered, resulting in high applicability.

[0055] The following describes specific embodiments of the present invention.

[0056] In some embodiments, the thermal property parameter measurement system based on heat flux of the present invention includes a flexible heat flux sensor, a thin-wire thermocouple, a flexible thin-film thermal resistance structure, a serpentine heater, and a thermal insulation structure. The system combines a constructed discrete transient heat conduction model to measure thermal property parameters. The system is a contact type, attached to the surface of the object being measured during measurement, with the heat flux sensor and thin-wire thermocouple in contact with the boundary of the object. The heat flux sensor measures the heat flux density through the boundary, the thin-wire thermocouple measures the temperature of the boundary, and the output voltage is detected and converted by the measurement circuit. The serpentine heater consists of a serpentine metal electrode and a polymer encapsulation, heated by a power supply, and the acquisition circuit records the system's output heat flux density and temperature. The discrete transient heat conduction model, with heat flux density as input, iteratively calculates the thermal conductivity and thermal diffusivity of the object being measured through an optimization algorithm, achieving quantitative thermal sensing. This system can accurately measure the thermal property parameters of an object, requiring only short-term data acquisition during contact. It features fast measurement speed, high accuracy, small size, light weight, portability, and ease of use and integration.

[0057] In some embodiments, the sensing element of the heat flux sensor is a thermopile whose output voltage signal is proportional to the heat flux. During measurement, it is located between the object under test and the serpentine heater to measure the heat flux density at the boundary of the object under test.

[0058] In some embodiments, the thermocouple is a thin-wire thermocouple with a small diameter thermocouple sensing node and wire. It is installed below the thin-film thermal resistance structure and comes into direct contact with the surface of the object being measured during application. The temperature is detected by the measuring circuit, thereby sensing the boundary temperature of the object in real time.

[0059] In some embodiments, the flexible thin-film thermal resistance structure has the same or similar material thermal properties as the heat flux sensor, the same thickness as the heat flux sensor used, and the same area as the serpentine heater, with its center cut into a hollow structure for mounting and embedding the heat flux sensor.

[0060] In some embodiments, the serpentine heater is composed of a serpentine metal electrode and a polymer encapsulation, and is led out by leads. Different heating powers can be achieved by changing different applied voltages. The structural parameters such as the shape and line width of the serpentine electrode depend on the actual measurement requirements.

[0061] In some embodiments, the thermal insulation structure is made of a low thermal conductivity material, located on the upper layer of the serpentine heater, has a certain thickness, and its vertical projected area is larger than the area formed by the heat flux sensor and the temperature measuring point of the thin-wire thermocouple.

[0062] In some embodiments, the discrete transient heat conduction model adopts a discretization solution method, treating the material under test as a semi-infinite object. The input of the model is the heat flux density measured by the system, and the control variables are the thermal conductivity and thermal diffusivity of the object under test. The model can calculate the temperature change of the object under a given boundary heat flux density, and the measurement result is obtained by combining the measured temperature with the fitting optimization algorithm.

[0063] In some embodiments, the flexible heat flux sensor, the thin-wire thermocouple, the flexible thin-film thermal resistance structure, the serpentine heater, and the thermal insulation structure are integrally encapsulated by a polymer.

[0064] The sensitive unit of the heat flux sensor consists of thermocouples connected in series to form a thermopile, which is mainly encapsulated in polyimide. It can measure the heat flux density passing through the sensor and its output is a voltage signal, which has high response speed and accuracy.

[0065] In some embodiments, the heat flux sensor has a thickness of 0.05 mm to 0.5 mm and an area of ​​5 mm × 5 mm to 20 mm × 20 mm, and is a flexible thin film structure.

[0066] In some embodiments, the flexible thin-film thermal resistance structure has the same thickness as the heat flux sensor and an area of ​​5mm×5mm to 60mm×60mm, depending on the area of ​​the heat flux sensor and the application scenario. It is made of polyimide or a material with thermal parameters similar to those of the heat flux sensor, and a hollow structure is created by laser or cutting processes for embedding and installing the heat flux sensor.

[0067] In some embodiments, the thin-wire thermocouple is used to measure the surface temperature of a target object, with the sensor measuring point diameter being 0.2 mm to 0.4 mm and the wire diameter being 0.025 mm to 0.075 mm.

[0068] In some embodiments, the serpentine heater is composed of a metal electrode and a polymer encapsulation, and is a flexible thin film structure with the same area as the flexible thin film thermal resistance structure, a thickness of 0.05 mm to 0.5 mm, and a metal electrode linewidth of 0.05 mm to 2 mm, depending on the structure of the heat flux sensor and the application scenario.

[0069] In some embodiments, the thermal insulation structure is made of polyurethane (PU), foam or other materials with low thermal conductivity, has the same area as the serpentine heater, and has a thickness of 10 mm to 60 mm.

[0070] In some embodiments, the first layer of the thermophysical parameter measurement system comprises a flexible heat flux sensor and a flexible thin-film thermal resistance structure (thermal resistance layer), wherein the heat flux sensor is embedded in the hollow structure of the thermal resistance layer, a thin-wire thermocouple is embedded beneath the thermal resistance layer, and a small amount of thermally conductive silicone grease is applied; the second layer is a serpentine heater, closely attached above the first layer; and the third layer is a thermal insulation structure (thermal insulation layer), closely attached above the serpentine heater. The entire system can be used directly for measurement, or it can be encapsulated by molding with a polymer (e.g., polydimethylsiloxane) for overall measurement.

[0071] like Figure 1 As shown, the thermal property parameter measurement system based on heat flux includes a heat flux sensor 2, a thin-wire thermocouple 3, a polyimide thermal resistance layer 4, a serpentine heater 5, and a polyurethane insulation layer 6. The heat flux sensor is installed in a medium-sized hollow structure in the polyimide thermal resistance layer 4, located between the object being measured and the serpentine heaters 1 and 5.

[0072] like Figure 1 As shown, the heat flux sensor 2 has a thermopile as its sensing unit. The output electrical signal is proportional to the heat flux density flowing through the sensor and is connected to an external circuit through lead wires from the electrodes.

[0073] like Figure 1 As shown, the projected area of ​​the polyimide thermal resistance layer 4 in the vertical direction is the same as that of the serpentine heater 5. A hollow structure is cut out according to the size of the heat flux sensor, and the thin wire thermocouple 3 is installed below the polyimide thermal resistance layer and is in direct contact with the surface of the object being measured.

[0074] like Figure 1 As shown, the thermal property parameter measurement system based on heat flux measures the thermal properties by contacting the object under test 1. The system can be directly attached to the object under test, or it can be encapsulated by injecting polymer PDMS or PU before measurement.

[0075] Figure 2 for Figure 1 The cross-sectional view of the system shown includes the object under test (1), heat flux sensor (2), thin-wire thermocouple (3), polyimide thermal resistance layer (4), serpentine heater (5), polyurethane insulation layer (6), PDMS encapsulation (7), and 8, which are schematic diagrams of heat flux density. In the application, power is supplied to the serpentine heater (5), and heat propagates into the object under test (1). The heat flux sensor (2) measures the heat flux density flowing into the boundary of the target object, and the thin-wire thermocouple (3) measures the temperature of the boundary of the object under test. The heat flux and temperature values ​​over a short period of time are substituted into the model for calculation and algorithm fitting.

[0076] like Figure 3As shown, the object under test is modeled by dividing it into N units perpendicular to the surface of the object, with a unit spacing of Δx. The time interval for each iteration of the discrete transient heat conduction model is Δτ. The surface temperature change of the object under test can be calculated by measuring the boundary heat flux density and the given thermal parameters.

[0077] In the preferred embodiment, the structural parameters of components such as the heat flux sensor, serpentine heater, and thin-film thermal resistance layer can be designed according to different application scenarios. The thermal insulation structure can be constructed using different types of materials or directly through actuators such as robotic arms, making the system easy to integrate with automatic control systems. Furthermore, the sensor used in the system has a flexible structure composed of metal and polymer, and the entire structure is encapsulated in polymer, exhibiting high robustness.

[0078] During operation, as a contact measurement system, the system is in close contact with the surface of the object being measured. While powering the serpentine heater, the circuit collects the output heat flux and temperature signals, which are then calculated using the following discrete transient heat conduction model.

[0079] The parameters of a discrete transient heat conduction model based on heat flux can be solved iteratively, as follows:

[0080] Treating the object under test as a semi-infinite object, and considering only heat transfer perpendicular to the object's surface in a short time, the object is discretized into N unit points. According to the law of conservation of energy, the boundary equation is:

[0081]

[0082] Where T represents temperature, i represents the iteration number, k is the thermal conductivity of the object being measured, ρ and c are the density and heat capacity of the object being measured, respectively, Δx is the discretized unit spacing, Δτ is the iteration time interval, and q is the heat flux density flowing into the object. For nodes 2 to N-1, the governing equations are:

[0083]

[0084] Where α is the thermal diffusivity of the object being measured. Since the object is assumed to be a semi-infinite object with a constant temperature at infinity, and the initial temperature of the object is T0, the lower boundary conditions and initial conditions of the system are as follows:

[0085]

[0086]

[0087] Given a set of thermophysical parameters of the material being tested, the surface temperature of the object can be calculated by measuring the heat flow rate through the system. Using the root mean square error between the theoretically calculated temperature and the actual measured temperature as the evaluation function, thermal conductivity and thermal diffusivity are calculated through a search algorithm (such as the least squares method).

[0088] Example 1

[0089] Aluminum alloy was selected as the measured material, with dimensions of 80mm × 80mm × 20mm. The system includes a 0.4mm thick heat flux sensor with an area of ​​10mm × 10mm, a serpentine heater with an area of ​​55mm × 60mm, a 0.4mm thick polyimide thermal resistance layer, a 30mm thick polyurethane insulation layer with an area of ​​50mm × 50mm, and a 0.05mm diameter T-type thermocouple. The measurement system was tightly fitted to the aluminum alloy surface. A digital multimeter was used to collect the output voltages of the heat flux sensor and the T-type thermocouple. An 18V voltage was applied to the serpentine heater, and the heat flux and temperature data were recorded within 2 seconds.

[0090] The thermal properties of the object under test are calculated using a discrete transient heat conduction model, in which Δτ is set to 1×10⁻⁶. -6 s, Δx is 4×10 -5 m, with heat flux as input and thermal conductivity and thermal diffusivity as variables, uses the root mean square error between the calculated theoretical surface temperature of the object and the actual temperature measured by the T-type thermocouple as the fitness value. The optimal result is calculated using the particle swarm optimization algorithm, thereby obtaining the thermal conductivity and thermal diffusivity of the object under test.

[0091] As an example, the particle swarm optimization algorithm used is an intelligent search algorithm, and its iterative update formula is:

[0092] v id =ω*v id +c1r1(p id -x id )+c2r2(p gd -x id )

[0093] x id =x id +v id

[0094] Here, the dimension of the particle is the input variable of the model, x. id p represents the current position of the i-th particle. id It is the historical best position of the i-th particle, p gd It represents the position of the globally optimal particle in the particle swarm, ω represents the inertia weight, c1 and c2 are learning factors, r1 and r2 are random numbers, and v idω is the current particle velocity, and ω is a scaling factor. The particle swarm iterates and evolves based on global and individual optima to obtain the particle with the optimal fitness.

[0095] The measured heat flux results are as follows Figure 4 The thermal conductivity of the tested object was calculated to be 124.7 W / (m·K), and the thermal diffusivity was 5.64 × 10⁻⁶. -5 m 2 / s, the fitting calculation result is as follows Figure 5 The corresponding aluminum alloy sample has a standard reference thermal conductivity of 120.4 W / (m·K) and a reference thermal diffusivity of 5.20 × 10⁻⁶. -5 m 2 / s, with relative errors of 3.57% and 8.46%, respectively.

[0096] Example 2

[0097] Tempered glass was selected as the measured material, measuring 80mm × 80mm × 20mm. The system included a 0.4mm thick heat flux sensor with an area of ​​10mm × 10mm, a serpentine heater with an area of ​​55mm × 60mm, a 0.4mm thick polyimide thermal resistance layer, a 30mm thick polyurethane insulation layer with an area of ​​50mm × 50mm, and a 0.05mm diameter T-type thermocouple. The measurement system was tightly fitted to the aluminum alloy surface. A digital multimeter was used to collect the output voltages of the heat flux sensor and the T-type thermocouple. A 22V voltage was applied to the serpentine heater, and the heat flux and temperature data were recorded within 2 seconds.

[0098] The thermal properties of the object under test are calculated using a discrete transient heat conduction model, in which Δτ is set to 1×10⁻⁶. -5 s, Δx is 4×10 -5 m, with heat flux as input and thermal conductivity and thermal diffusivity as variables, uses the root mean square error between the calculated theoretical surface temperature of the object and the actual temperature measured by the T-type thermocouple as the fitness value. The optimal result is calculated using the particle swarm optimization algorithm, thereby obtaining the thermal conductivity and thermal diffusivity of the object under test.

[0099] The measured heat flow results are as follows Figure 6 The thermal conductivity of the tested object was calculated to be 1.13 W / (m·K), and the thermal diffusivity was 5.66 × 10⁻⁶. -7 m 2 / s, the fitting calculation result is as follows Figure 7 The corresponding tempered glass sample has a standard reference thermal conductivity of 1.097 W / (m·K) and a reference thermal diffusivity of 5.52 × 10⁻⁶. -7 m 2 / s, with relative errors of 3.0% and 2.54%, respectively.

[0100] In summary, the thermal property parameter measurement system and method based on heat flux of this invention can be directly used in the execution terminal to perform contact quantitative thermal sensing of the target object. It has the advantages of fast measurement speed, high accuracy, strong robustness and small size.

[0101] The main advantages of this invention compared to traditional technologies are:

[0102] This invention addresses the shortcomings of current qualitative thermal measurement and recognition methods, providing more multi-dimensional information for intelligent tactile feedback. It solves the problem of quantitative measurement of object thermal parameters in portable thermal sensing modes. It also solves the problem of quantitative recognition of objects at different room temperatures, eliminating the need for precise initial temperature measurement and temperature compensation. Furthermore, it overcomes the errors caused by excessive complexity and numerous variables in previous models.

[0103] This invention enables accurate measurement of the thermal properties of objects made of different materials, requiring only a short period of data acquisition during contact. It boasts high measurement speed and accuracy, and the system is small, lightweight, portable, easy to use, and easily integrated. The system exhibits good measurement stability, and the proposed model, based on the boundary temperature and boundary heat flux density of the target object, represents a promising and valuable method for measuring thermal parameters.

[0104] This invention improves measurement accuracy and simplifies the heat transfer model based on a measurement scheme for heat flux and boundary temperature. It also enhances the stability of quantitative thermal perception and enables portable measurement of thermal parameters. This is of great significance for identification and perception, tactile reproduction, virtual reality, and other fields, laying the foundation for the development of large-scale commercial consumer electronics.

[0105] The solution of this invention exhibits good stability in various environments and is easy to integrate. Specific application scenarios are as follows:

[0106] 1. Robot object recognition and grasping: The robot can use this system in conjunction with other sensors to perceive the shape, material, color and other features of the object being measured, and obtain the thermal information of the object, so as to grasp and process the object more accurately.

[0107] 2. Tactile Reproduction and Virtual Reality: The invented measurement system has advantages such as miniaturization and portability, and can be used for tactile reproduction, such as simulating a realistic tactile experience in virtual reality. The system can detect the physical information of real-world objects and transmit this information to the virtual reality environment. Combined with technologies such as vibration feedback devices, it can achieve tactile reproduction.

[0108] 3. Remote Thermal Sensing Reproduction: The invented system can be used for remote thermal sensing reproduction, such as in telemedicine and remote detection. In these scenarios, sensors can sense the temperature, heat, and thermal parameters of an object and transmit this information to a remote user's device. Combined with actuators, this allows the user to experience the thermal sensation of a remote object.

[0109] 4. Industrial Automation: In industrial automation scenarios, this system can be used to sense objects on industrial equipment and production lines for tasks such as object classification, counting, and sorting. Furthermore, the system can also be used to detect parameters such as temperature and heat in industrial equipment for equipment condition monitoring and predictive maintenance.

[0110] 5. Smart Home, IoT, Consumer Electronics, etc.: In smart homes and IoT, this system can be used to sense the temperature and heat information of the surrounding environment, as well as the thermal parameters of objects in contact with it, and transmit this information to the smart home system for intelligent temperature control and energy management. In consumer electronics, the system has a thin-film structure and can be integrated into smart bracelets, combining thermal data of the human body for texture recognition and health monitoring.

[0111] This invention has particular market value for industries such as robot grasping and recognition, automation, tactile reproduction, and virtual reality, with the following advantages:

[0112] 1) This system is miniaturized and attachable, making it easy to integrate into existing robot equipment. It provides an efficient, low-cost, and modular solution for improving intelligent robots and automated control equipment.

[0113] 2) This system can measure the thermal parameters of an object under contact, providing more dimensions of information for thermal perception, and greatly improving the accuracy of recognition and the ability to acquire object information and physical characteristics.

[0114] 3) The system of the present invention is based on a physical heat transfer model, which can simulate a real tactile experience in virtual reality and can also be used for remote tactile reproduction, greatly enhancing the user experience and strengthening the competitiveness of existing products.

[0115] The background section of this invention may include background information about the problems or environment in which the invention is being developed, and is not necessarily a description of prior art. Therefore, the content included in the background section does not constitute an admission of prior art by the applicant.

[0116] The above description provides a further detailed explanation of the present invention in conjunction with specific / preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the scope of protection of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. A method of measuring a thermophysical parameter based on heat flux, characterized in that, The application relates to a thermal physical parameter measurement system based on heat flux, which comprises a heat flux sensor, a temperature sensor and a heater, one side of the heat flux sensor is in contact with the surface of a measured object, the other side of the heat flux sensor is provided with the heater, the heater covers the heat flux sensor on the heat transfer surface of the measured object, the heat generated by the heater is conducted to the measured object through the heat flux sensor, the heat flux sensor is used for measuring the heat flow density through the boundary of the measured object, and the temperature sensor is arranged on the surface of the measured object in a manner equivalent to being arranged on the side of the heat flux sensor in contact with the measured object, and the temperature sensor is used for measuring the temperature of the boundary of the measured object. The measurement method comprises the following steps: according to the measured heat flow density and temperature, the thermal physical parameters of the measured object are determined by constructing a discrete transient heat conduction model, and the method specifically comprises the following steps: The measured object is regarded as a semi-infinite object, and the object is discretized into N unit points in the direction perpendicular to the surface, and the boundary equation for heat transfer is as follows: wherein T denotes the temperature, i denotes the iteration number, k is the thermal conductivity of the object under test, For the 2th to N-1th nodes, the control equation is as follows: and c are the density and the heat capacity of the object under test, respectively, Δ x is the discretized cell point spacing, and Δτ is the iteration time interval, q is the heat flux flowing into the object; According to the measured heat flow density, the theoretical temperature of the surface of the measured object is calculated based on the given thermal conductivity and thermal diffusivity of the measured object. wherein, α is the thermal diffusivity of the object under test; The initial temperature of the object is T 0, the lower boundary condition and the initial condition are: An evaluation function is constructed based on the error between the calculated theoretical temperature and the actually measured temperature, and the thermal conductivity and thermal diffusivity of the measured object are obtained from the parameters corresponding to the minimum error through iterative solution and fitting calculation. The heat flux sensor is a flexible heat flux sensor, and the sensitive unit of the heat flux sensor is a thermocouple.

2. The heat-flux-based thermophysical parameter measurement method of claim 1, wherein, The covering area of the heater on the heat flux sensor is larger than the covering area of the heat flux sensor on the measured object, the temperature sensor is arranged on the surface of the measured object which is in the covering area of the heater and out of the covering area of the heat flux sensor, and a thermal resistance layer is arranged between the temperature sensor and the heater.

3. The heat-flux-based thermophysical parameter measurement method of claim 1, wherein, The heat flux sensor is a polyimide package, and the thermal resistance layer is a polyimide layer.

4. The heat-flux-based thermophysical parameter measurement method of claim 3, wherein, The thickness of the thermal resistance layer is the same as that of the heat flux sensor, and the area of the thermal resistance layer is the same as that of the heater, the middle of the thermal resistance layer is a hollow structure and is used for mounting the heat flux sensor.

5. The heat-flux-based thermophysical parameter measurement method of claim 3, wherein, The temperature sensor is a thin-wire thermocouple.

6. The heat-flux-based thermophysical parameter measurement method of claim 3, wherein, The side of the heater away from the heat flux sensor is provided with a heat insulation structure.

7. The heat-flux-based thermophysical parameter measurement method according to any one of claims 1 to 6, characterized in that, The root mean square error between the calculated theoretical temperature and the actually measured temperature is taken as an evaluation function, and the thermal conductivity and thermal diffusivity of the measured object are obtained through least square fitting calculation.

8. The heat-flux-based thermophysical parameter measurement method according to any one of claims 1 to 6, characterized in that, ​

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