DE102020208813A1 - Method for determining a person's temperature, computer program, storage medium, measuring arrangement and black body radiator - Google Patents

Abstract

Method for determining the temperature of a person 2 in a monitoring area 3, the monitoring area 3 being detected by a thermal sensor 4 and sensor data being provided by the thermal sensor 4, the person 2 and a blackbody radiator 5 being arranged in the monitored area 3 detected by the sensor, wherein the sensor data comprises a first radiant power and a second radiant power, the first radiant power forming a thermal radiant power of a section of a person detected by the thermal sensor 4, the second radiant power forming a thermal radiant power of a black-body radiator section 9 detected by the thermal sensor 4, the temperature of the person 2 being based is determined on the first and second radiant power.

Description

State of the art

The invention relates to a method for determining the temperature of a person in a surveillance area.

Devices and methods for determining a surface temperature of a measurement area are known in the prior art. The same devices and/or methods are used, for example, to determine the surface temperature of electronics, test objects and/or people.

For example, the reference discloses DE 10 2014 226 342 A1 , which probably forms the closest prior art, a hand-held thermal imaging camera for non-contact measurement of a temperature of a measurement area located on a surface. The thermal imaging camera includes a detection surface with a large number of pixels for detecting thermal radiation emitted from the measurement area. The thermal imaging camera has optics for imaging thermal radiation emitted from the measurement area onto the detection surface while illuminating a plurality of pixels, and an evaluation device for receiving and evaluating detection signals from the detection device, with each pixel of the detection device being able to be connected to the evaluation device in terms of signals.

Disclosure of Invention

A method for determining the temperature of a person in a surveillance area with the features of claim 1 is proposed. Furthermore, a computer program with the features of claim 12, a measuring arrangement with the features of claim 13 and a blackbody radiator with the features of claim 14 are proposed. Preferred and/or advantageous embodiments of the invention result from the dependent claims, the description and the attached figures.

The invention relates to a method for determining the temperature of a person in a surveillance area. In particular, the method is designed for contact-free determination of the temperature. The method can be designed to determine a surface temperature of the person, for example skin temperature. Alternatively and/or additionally, the method is designed to determine a core temperature of the person. The temperature of the person, in particular the absolute temperature, can be determined independently of the distance by means of the method.

The monitored area is, for example, an indoor area. The monitoring area is particularly preferably designed as an entrance, as an airlock, as a door, as an entry or control point. For example, the monitored area can represent access to an airport section, for example a gate, in which case the person in the monitored area is to be checked for increased temperature, for example fever, in particular in order to minimize chains of infection. The monitoring area is set up in particular to provide for a security check, for example baggage, security or personal checks, in addition to determining the temperature. In particular, the method is set up and/or designed to use a measuring arrangement described below and/or black-body radiators for improved determination of the person's temperature. The method can, in particular, be computer-implemented, specifically also using a neural network.

The method provides for the monitoring area to be detected and/or monitored by a thermal sensor. For example, the thermal sensor is aimed at the monitored area. The thermal sensor, for example, detects objects, in particular people, who are arranged in the monitored area or pass through it, using sensors. The thermal sensor is designed to provide sensor data, the sensor data comprising the monitoring area detected by the thermal sensor, information and/or thermal radiation. The thermal sensor is preferably designed as a microbolometer. In particular, the thermal sensor can and/or is designed as an IR camera and/or thermal imaging camera. The thermal sensor includes, for example, a detection area, the detection area including pixels.

The thermal sensor is designed to capture and/or detect thermal radiation of the monitored area detected by the sensor and to make it available as sensor data. In particular, in addition to infrared radiation, for example medium and/or long infrared radiation, the thermal sensor additionally detect visible radiation and/or UV radiation. It is particularly preferred that the thermal sensor is designed to detect and/or record infrared radiation with a wavelength greater than 3 μm, in particular greater than 10 μm. Furthermore, the thermal sensor can be designed to record and/or detect thermal radiation up to a limit wavelength, for example 50 μm. The thermal sensor is preferably arranged and/or aligned in a fixed manner, for example mounted on a ceiling and/or a wall. In particular, the orientation and/or the perspective of the thermal sensor on the monitored area is fixed and/or constant. Alternatively, the detection area and/or the alignment of the thermal sensor can be aligned and/or adjustable, so that the thermal sensor or its detection area can be targeted, controlled and/or randomly aligned to different sections and/or monitoring areas. In particular, the thermal sensor, or its detection range and/or perspective, can be tracked, for example in order to recognize and/or evaluate a person more precisely.

The method provides for a person located in the monitored area and/or a person passing through the monitored area to be detected by the thermal sensor using sensors. For example, the method provides for the permanent, continuous and/or cyclical detection and/or provision of sensor data by detecting the monitored area, so that a person in the monitored area is also detected by the thermal sensor.

The method provides that a black body radiator, in particular an extended area black body radiator, is arranged in the monitoring area. The thermal sensor is oriented and/or arranged to detect the blackbody radiator in the surveillance area and provide the detection as sensor data. The blackbody radiator is preferably at least partially an optimal or near-optimal blackbody. In particular, the blackbody radiator is temperature-controlled, with the temperature of the blackbody radiator being controlled. The blackbody radiator is tempered to an adjustable and/or fixed temperature. The black body radiator or its temperature can be understood as a reference temperature and/or reference radiator.

The sensor data includes a first radiant power and a second radiant power. The first radiant power forms and/or describes a thermal radiant power that emanates from a section of a person. For example, the person section can represent a face and/or a face section of the person in the surveillance area. In particular, several parts of the person and/or thermal radiation power of parts of the person can be determined and/or detected. The first radiation power can be understood, for example, as a radiation power that emanates from a section in the monitored area where the person is located. The second radiant power forms, includes and/or describes a thermal radiant power of a blackbody radiator section detected by the thermal sensor. The blackbody radiator section is in particular a section of the blackbody radiator, this section corresponding in particular to an ideal and/or almost ideal (technically realizable) blackbody. For example, the black body radiator section has an absorption coefficient of epsilon approximately one. The second radiant power and/or the thermal radiant power of the blackbody radiator section describes, for example, a thermal radiant power that emanates from an area and/or section of the monitored area where the blackbody radiator is located. The second radiant power thus describes in particular a radiant power that does not emanate from the person, at least not explicitly.

The method provides that the temperature of the person, in particular maximum temperature, surface temperature and/or core temperature, is determined based on the first and the second radiation power. For example, the first radiant power and the second radiant power can be used to analytically determine the temperature. Alternatively and/or additionally, the temperature can be determined based on the first and the second radiant power using a characteristic curve and/or reference parameters.

The invention is based on the consideration that when determining a temperature, in particular of a person, a wide variety of environmental influences, scene-specific influences and/or surrounding objects have an influence on a precise temperature determination. For example, the environment also emits thermal radiation, which is detected by the thermal sensor and would thus, for example, falsify the determination of the person's temperature. On the other hand, thermal radiation from the object is attenuated as it transmits and/or passes through the path to the thermal sensor. In order to be able to take such errors, both weakening and amplification, into account, in addition to the pure detection of the human section, a black-body radiator or black-body radiator section is detected by means of the thermal sensor, with this being temperature-controlled and thus serving as a kind of reference and/or comparison can. In particular, the blackbody radiator section can be used to take into account physical, in particular thermodynamic, processes and/or scene-specific disturbances.

In particular, the method provides that the person's temperature is determined based on a thermodynamic model. In particular, the thermodynamic model provides for the consideration of weakening effects, for example due to convection, transmission and/or reflection. Furthermore, the thermodynamic model provides, for example, amplifying environmental effects, for example radiation from surrounding objects, portions reflected by the object and/or thermal radiation in the air. In particular, the thermodynamic model is based on the Stefan-Boltzmann law. For example, the thermodynamic model provides that a thermal radiation power that can be detected and/or detected by the thermal sensor includes a personal radiation component and an ambient radiation power component, with the ambient radiation power component being determined based on the second radiation power. In other words, the thermodynamic model provides, for example, that a radiant power detected by the thermal sensor, in particular by the microbolometer and/or the thermal imager, typically requires accurate calibration and/or scene-specific parameters, such as reflected thermal radiation from other objects in the environment and thermal radiation of the air must be taken into account. For example, the thermodynamic model takes into account that a radiant power P emitted by an object, e.g. the person or the blackbody radiator ^{, satisfies the relationship P = ∈σAT 4} , where ∈ is the emissivity of the body, σ is the Stefan-Boltzmann constant, A is the radiating area and T is the absolute temperature. By the use of a thermal sensor, for example microbolometer, the thermodynamic model can be described, for example in the form that the readout from one pixel temperature T and the measured thermal radiation power P _M satisfies the relation P _M = ∈ _cal σAT. ⁴ In particular, the thermodynamic model, which includes a measured thermal radiant power P _{M ,} takes into account several components, for example the radiant power P of the actual object, for example the person, a mean effective radiant power P _E , which includes radiant power emanating from surrounding objects and reflected on the object, as well as a radiant power P _A starting from the air between object. For example, the thermodynamic model can be written as P _M = τ[P + (1 - ∈)P _E ] + (1 - τ)P _A .

It is particularly preferred that a core temperature T _{C of} the person is determined by means of the method. In particular, the core temperature is determined based on a difference between a person _{'s surface temperature T S} , surface temperature for short, and a core-surface temperature difference ΔT _C,S . In particular, the core-surface temperature difference is a scene-specific quantity. For example, the core-surface temperature difference can take into account wind chill effects, air humidity aspects, evaporative cooling and/or air flow effects. The core-surface temperature difference indicates, for example, how big a difference between surface temperature and core temperature is, in particular taking into account environmental parameters and/or scene-specific variables. For example, the method provides that a surface temperature of the part of the person, in particular the person, is determined, with the core-surface temperature difference being taken into account for determining the core temperature, for example being added or subtracted. For example, this can be taken into account by the thermodynamic model. In particular, the following applies to the core temperature T _C =T _S (x,y) − ΔT _C,S (x,y), where x, y describe a position on the person or the part of the person.

In a particularly preferred embodiment, the method provides for the core temperature to be determined based on a maximum person surface temperature T _S,max . In particular, it is provided that a minimum core-surface temperature difference ΔT _{C,S,min is} used and/or determined to determine the core temperature. This configuration is based on the consideration that temperature differences between the core and surface of a person depend on the position at which the surface temperature or skin temperature is determined. For example, certain parts of the body, such as the nose, are further from the core and/or cooler. Areas around the eye are usually warmer and especially closer to a body center. In order to determine the core temperature, it is therefore particularly advantageous to determine a maximum person surface temperature, in other words the warmest point on the body surface, with a minimum core-surface temperature difference being specifically to be calculated here. The core-surface temperature difference is in particular a scene-specific variable, for example dependent on the air humidity. In order to ensure a good and reliable temperature determination of the core temperature, it is therefore advantageous to use individual minimum core-surface temperature differences.

In particular, the method provides that face recognition is applied to the sensor data and/or based on the sensor data to determine the maximum surface temperature. This configuration is based on the consideration that the warmest area of the person and/or a person is usually found in the face. Other areas, for example arms, legs, upper body, are often covered by textiles and/or several layers of textiles, so that lower temperatures are measured here. By determining and/or recognizing the position of the face and/or the face of the person in the sensor data, the maximum surface temperature can be determined specifically in this area. In particular, this embodiment provides that obscuring and/or shielding by objects, such as glasses or a face mask, are taken into account when determining the maximum surface temperature and/or similar areas are excluded.

The method provides, for example, that an air radiation power is taken into account to determine the temperature of the person, in particular the surface temperature and/or the core temperature of the person, and/or the ambient radiation power component includes the air radiation power. In the latter case, the thermodynamic model includes and/or takes into account the air radiation power, for example. The air radiation power and/or an air temperature associated with the air radiation power is determined and/or determined in particular based on the radiation power of the black body, in particular the black body radiator section, with a black body section temperature being taken into account in particular. The blackbody portion temperature is, for example, an actually measured temperature of the blackbody radiator portion, for example, by contact temperature measurement. Alternatively and/or additionally, the blackbody portion temperature may be considered as a set and/or controlled temperature of the blackbody radiator. The air radiation power describes in particular an influence on a measured radiation power of the thermal sensor which emanates from the surrounding air or its temperature. This configuration is based on the consideration that by checking a blackbody section temperature and/or directly determining the blackbody section temperature and measuring the radiant power of the blackbody radiator section using the thermal sensor, the influence of the air radiant power on the temperature determination of the person can be determined and taken into account. For example, the radiant power of the blackbody radiator, in particular of the blackbody radiator section, is determined by means of the thermal sensor and the actual, for example measured or controlled, blackbody section temperature is compared with the measured temperature. In particular, this is based on the consideration that the blackbody radiator section absorbs radiation ideally and/or almost ideally or is not reflective (∈ ≈ 1), so that when using the thermodynamic model, for example, reflective radiation power components are neglected and/or not taken into account.

In particular, it is provided that an average reflected radiation power is taken into account to determine the temperature of the person, for example surface temperature and/or core temperature. For example, the ambient radiation power component includes the average reflected radiation power. For this purpose, for example, a temperature of a reflecting reflector section is determined by means of the thermal sensor. Specifically, a portion of the blackbody radiator in which the reflective reflector portion is disposed is detected by the thermal sensor. For example, a reflective foil, surface and/or element is arranged on the blackbody radiator for this purpose. For example, the reflector portion is formed as a portion of the blackbody radiator covered with gold foil or silver foil. The sensor data includes the reflector radiant power. The reflector radiant power is, in particular, a thermal radiant power detected by the thermal sensor, starting from the reflector section. For example, it is provided that the mean reflected radiant power and/or the associated mean reflection temperature, in particular measured reflection temperature, is determined based on the measured reflector radiant power and the associated actual temperature, for example the blackbody section temperature. This configuration is based on the consideration that by detecting a reflector section using the thermal sensor, ∈≈0 can be used, so that the thermodynamic model and/or the formulas to be used physically can be greatly simplified.

It is optionally provided that for determining the temperature of the person, for example surface temperature and/or core temperature, a transmittance τ of the air and/or a calibration emissivity ∈ _{cal of} the thermal sensor is taken into account, for example taken into account by the thermodynamic model. In particular, the transmittance τ=τ(d) depends on a distance d between the thermal sensor and the object or person. The transmittance and/or the calibration emissivity can be determined, for example, for the measuring arrangement for carrying out the method, by means of one or more series of measurements. Furthermore, the transmittance and/or the calibration emissivity can be determined, extracted and/or provided based on a characteristic. The characteristic curve and/or the series of measurements includes and/or is based on thermal radiation powers of the blackbody radiator section at different blackbody section temperatures and/or different distances between thermal sensor and blackbody radiator. For example, here at and/or were here at, thermal radiation power of the blackbody section is determined and/or measured by means of the thermal sensor, with the temperature, for example the set temperature, of the blackbody radiator section and/or the distance between the thermal sensor and the blackbody radiator section being varied.

In particular, it is provided that the core-surface temperature difference is interpreted as a sum of a constant core-surface temperature difference and a scene-dependent core-surface temperature difference offset. For example, the constant core-surface temperature difference can describe an average human value, which is taken from the literature, for example, and/or is based on one or more series of measurements. In particular, the constant component can be designed to be location-dependent, for example dependent on a part of the body, e.g. nose, eyes, forehead-specifically. The scene-dependent core-surface temperature difference offset is dependent in particular on air humidity, air flow, ambient temperature and/or other ambient parameters. The scene-dependent core-surface temperature difference offset can be taken from a stored characteristic curve and/or reference table, alternatively the scene-dependent offset can and/or is determined by one or more measurements for the scene.

It is particularly preferred that the scene-dependent core-surface temperature difference offset is determined based on the sensor-based monitoring of a shielding section of the black-body radiator. For this purpose, the black-body radiator has, for example, a shield as a shielding section, the shield covering, for example, a section of the surface of the black-body radiator. Preferably, the physical, chemical and/or thermodynamic parameters of the shield is and/or are similar to those of a person, in particular skin and/or facial portion. For example, the shield has a similar degree of emission and/or absorption. The shielding section is in particular temperature-controlled at at least one point, for example temperature-controlled to the black-body section temperature on the side facing away from the thermal sensor. The shield portion is detected by the thermal sensor, and the sensor data includes this as a shield radiation performance. The scene-dependent core-surface temperature difference offset is determined based on shield radiation power. This configuration is based on the consideration that by introducing a shield on the blackbody radiator, which behaves in a manner similar to the surface of a person in terms of radiation, the scene-dependent core-surface temperature difference offset can be estimated and/or determined.

In particular, it is provided that the core temperature of the person is based on the set temperature of the blackbody section, also called blackbody section temperature, the measured and/or set temperature of the reflector section and the shielding section, the first radiant power, the second radiant power, the reflector radiant power and the shielding radiant power . This embodiment is based on the consideration that a thermodynamic model can be used through these quantities and/or parameters that ensures a safe, good and reliable determination of the person's core temperature, with all significant environmental influences being taken into account in particular.

A further object of the invention is a computer program. In particular, the computer program can be executed on a computer. The computer program is designed, when executed, to determine the temperature of a person, for example absolute temperature, surface temperature and/or core temperature. In particular, the method as previously described is executed and/or processed by the computer program for the purpose of determination.

A further object of the invention is a machine-readable storage medium, the computer program being stored on the machine-readable storage medium.

A further object of the invention is a measuring arrangement for determining the temperature of the person, in particular the surface temperature and/or core temperature. The measuring arrangement includes the thermal sensor, in particular the microbolometer, the black body radiator and an evaluation unit tion. In particular, the evaluation device is designed and/or set up to execute the computer program and/or the method as previously described. The thermal sensor is arranged and/or designed to detect the black-body radiator and the person in the monitoring area using sensors. The thermal sensor is designed to provide the evaluation device with the sensor data. Furthermore, the controlled and/or set temperature of the black-body radiator, the black-body radiator section, the reflector section and/or the shielding section is made available to the evaluation device.

A further subject matter of the invention is a blackbody radiator. The blackbody radiator has a blackbody radiator section and a reflector section and/or shielding section. The shielding section is in particular formed as a covering of the blackbody section and/or blackbody. The shielding section preferably has a degree of emission and/or degree of absorption similar to that of human skin. The reflector section is, for example, a section with no and/or very low thermal absorption. For example, the reflector portion is a portion of the blackbody radiator covered with gold foil, silver foil, or reflective foil.

• 1 ein Ausführungsbeispiel einer Messanordnung;
• 2a, b, c Komponenten eines Schwarzkörperstrahlers;
• 3a, b Schwarzkörperstrahler aus 2.

Further advantages, configurations and effects result from the accompanying figures and their description. show:

• 1 an embodiment of a measuring arrangement;
• 2a, b , c components of a blackbody radiator;
• 3a, b Black body radiator off 2 .

1 shows a measuring arrangement 1 for determining a temperature of a person 2 in a monitoring area 3. The monitoring area 3 is designed as a section of a building, for example an airport. The monitored area 3 is detected by a thermal sensor 4, the thermal sensor 4 being designed as a thermal imaging camera, in particular a microbolometer. The monitoring area 3 detected by the thermal sensor 4 comprises a black body radiator 5 and the person 2, with at least a torso and/or face section being detected from the person. For example, an entrance and/or lock 6 is recorded as the monitoring area 3 . The lock 6 is used, for example, for person checks, in particular passport, face and/or security checks of the person 2. In particular, the lock is designed to correctly orient the person 2 when passing, so that the thermal sensor can detect the face section of the person 2. The thermal sensor 4 detects the thermal radiation power emitted by the person 2 and the black body radiator 5 and makes this available as sensor data. The distance between thermal sensor 4 and person 2 and/or black body radiator 5 is approximately 3 to 5 meters. For example, the sensor data is provided to an evaluation device, which provides the personal temperature, surface temperature and/or core temperature based on the sensor data. Security and/or control personnel 8 can thus, for example, subject persons with an elevated temperature to a further check or deny access.

2a, b , c show examples of components of the blackbody radiator 5. 2a FIG. 1 shows a basic black-body module 8 which comprises a black-body radiator section 9 and a housing section 10 . The blackbody radiator section 9 is a flat, in particular central section which has an absorptivity of approximately 1 and forms a blackbody radiator. In particular, the black-body radiator section 9 can be described by the black-body law and the Stefan-Boltzmann law. The blackbody radiator section 9 is tempered to a blackbody section temperature.

2 B 12 shows a shield 11 which is designed for attachment to the blackbody radiator 5, in particular the blackbody radiator section 9. FIG. The shielding 11 is flat and has an absorptivity and an emissivity for thermal radiation that is similar to human skin. The shielding 11 has recesses 12, the recesses 12 releasing the blackbody radiator section 9 when the shielding is in the fastened state. When mounted, the shield is back tempered by the tempering of the black body radiator section, either by heat flow due to direct contact or heat radiation through the optional air gap.

2c shows a reflector 13, the reflector 13 having an emissivity of about 1. The reflector is designed as a metallic frame, for example made of silver. The reflector 13 surrounds a central free area which, in a mounted state of the reflector on the black body radiator, in particular the shield 12, parts of the shield and the black body radiator section 9 releases.

3a FIG. 12 shows a plan view of a blackbody radiator 5 comprising the components from FIG 2a, b , c . The blackbody radiator 5 comprises the blackbody radiator section 9, a shielding section 14 and a reflector section 15. 3b shows a side view of the blackbody radiator 5, it being particularly evident that a small air gap can be arranged between the blackbody radiator section 9 and the shielding 11.

The sensor data are evaluated to determine the temperature of the person 2 , the sensor data including the sensor-based monitoring of the black-body radiator 5 and the person 2 . The method can be used to determine an absolute surface temperature of person 2, in particular independently of the distance between person 2 and thermal sensor 4. Furthermore, a scene-specific temperature difference between the core and the surface of the person can be determined using the method.

The core temperature, also core body temperature, of the person can be described by the relationship T _C = T _S (x,y) - ΔT _C,S (xy), where T _{C is} the core temperature, T _{S is} the surface temperature, ΔT _{C/S is} the temperature difference between of core temperature and skin and x,y are body surface coordinates.

The temperature difference between the core and the surface depends on the position of the surface section. Some portions, such as portions near the subject's eyes, have a temperature closer to the subject's core temperature than other portions, such as the nose. By focusing on higher temperature portions, such as eyes, the equation T _C = T _S,max - ΔT _C/S,min can be used, where T _{S,max is} the maximum skin temperature and ΔT _{C/S,min is} the minimum temperature difference between core temperature and skin.

The determination of absolute temperature values of the skin from the sensor data of the thermal sensor 4 is often difficult and requires an exact calibration of the thermal sensor 4 and the consideration of environmental parameters, for example reflected thermal radiation from surrounding objects and thermal radiation in the air. In order to determine the maximum skin temperature of person 2, face recognition can be carried out, for example, so that the maximum skin temperature is determined by measuring the face. Determining the minimum temperature difference between core and surface is usually non-trivial and requires knowledge of scene-specific thermodynamic coupling of environment and person. This coupling depends, for example, on the heat transport through convection, air pressure, humidity and other parameters.

The procedure is based on the Stefan-Boltzmann law P = εσAT ⁴ . where P is the radiant power of the object, ε the object emissivity, range [0,1], σ Stefan-Boltzmann constant, 5.670373 - 10 ^-8 Wm ^-2 K ^-4 , A the project surface and T the object temperature.

To determine the radiant power, the thermal sensor 4 is designed as a microbolometer with a number of pixels. The thermal sensor 4 is designed to detect radiation with a wavelength between 7 and 14 μm in the individual pixels in order to generate a thermal image of the monitored area, for example.

The relationship between the measured thermal radiation P _M and the pixel temperature read out can be described as P _M = ε _cal σAT _{M 4} where P _{M is} the measured power, ε _{cal is} the emissivity for calibration of thermal cameras and T _{M is} the temperature reading on the thermal camera.

The measured thermal radiant power includes three components, the radiant power emanating from the person, the average reflected radiant power from surrounding objects, and the radiant power of the surrounding air. This leads to the thermodynamic model P _M =
τ[P + (1 - ε)P _E ] + (1 - τ)P _A , where τ transmittance for transmission in air, τ ≈ 0.9 for 2m distance, P _{E is} the effective radiant power emitted by all other objects in the Environment is radiated and P _{A is the} radiant power that is radiated from the air.

wobei T die gesuchte Objekttemperatur, T_M die gemessene Temperatur ist und T_E und T_A unbekannt und szenenspezifisch sind.This thermodynamic model can be used to determine the absolute temperature of the person. This model can be simplified by eliminating the radiant power of the air. The connection is based on the Stefan Boltzmann law $e_{cal}{T}_M^4=\tau \left[e{T}^4+\left(1-e\right)T{E}^4\right]+\left(1-\tau \right)T_A^4,$

where T is the object _{temperature sought, T M is} the measured temperature, and T _E and T _{A are} unknown and scene-specific.

wobei T_M,BB die Temperatur des erweiterten Schwarzkörperstrahlers, τ_BB Transmittance der Luft für den Abstand d_BB, ε_BB Emissionsgrad der Schwarzkörpers (ε_BB = 1) und TBB Schwarzkörperabschnittstemperatur. $$\text{Wegen}{\epsilon }_{BB}=1\text{ergibt sicht}{T}_A^4=\frac{{\epsilon }_{cal}{T}_M{}_{,BB}^4-{\tau }_{BB}{T}_{BB}^4}{1-{\tau }_{BB}}.$$

In order to eliminate the temperature of the surrounding air from the equation, the black-body radiator section 9 is detected by sensors using the thermal sensor 4 . This gives the connection $e_{cal}{T}_M{}_{,BB}^4={\tau }_{BB}\left[e_{BB}{T}_{BB}^4+\left(1-e_{BB}\right)T_E^4\right]+\left(1-{\tau }_{BB}\right)T_A^4,$

where T _{M,BB is} the temperature of the extended blackbody radiator, τ _BB transmittance of the air for the distance d _BB , ε _BB emissivity of the blackbody (ε _BB = 1) and TBB blackbody section temperature. $$\text{Because}{e}_{BB}=1\text{results in <figure-callout id="4" label="view T A" filenames="DE102020208813A1\_0016.png" state="{{state}}">view</figure-callout>}{T}_A^{}{}_4^{}=\frac{e_{cal}{T}_M{}_{,\mathrm{<figure-callout\; id="4"\; label="B\; B"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">B</figure-callout>}B}^4-{\tau }_{BB}{\mathrm{<figure-callout\; id="4"\; label="T\; B\; B"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">T</figure-callout>}}_{BB}^{}}{1-{\tau }_{BB}}.$$

wobei T_M,R die mit dem Thermosensor gemessene Temperatur des Reflektors, τ_R Transmissionsgrad der Luft ist und ε_R Emissionsgrad des Reflektors (ε_R ≈ 0).The radiant power of the reflector section 14 is measured to eliminate the variable T _{E .} This size can be described as $e_{cal}{T}_M{}_{,R}^4={\tau }_R\left[e_R{T}_R^4+\left(1-e_R\right)T_E^4\right]+\left(1-{\tau }_R\right)T_A^4,$

where T _{M,R is} the temperature of the reflector measured with the thermal sensor, τ _{R is the} transmittance of the air and ε _{R is the} emissivity of the reflector (ε _R ≈ 0).

Dies impliziert, dass die mittlere Strahlungsleistung von reflektierter Strahlung der umgebenden Objekte am Objekt aus dem thermodynamischen Modell eliminiert werden kann, durch das Wissen der Temperatur des Schwarzkörperstrahlerabschnitts, sensortechnischen Erfassung des Schwarzkörperstrahlerabschnitts und des Reflektorabschnitts.By assuming ε _R = 0 and replacing by ${\text{<figure-callout id="4" label="T A" filenames="DE102020208813A1\_0016.png" state="{{state}}">T</figure-callout>}}_{\text{A}}{}^4\text{surrendered}{\mathrm{<figure-callout\; id="4"\; label="T\; E"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">T</figure-callout>}}_E^{}={\mathrm{<figure-callout\; id="4"\; label="T\; B\; B"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">T</figure-callout>}}_{BB}^{}+\frac{e_{cal}}{{\tau }_{BB}}\left(T_M{}_{,\mathrm{<figure-callout\; id="4"\; label="R"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">R</figure-callout>}}^4-T_M{}_{,BB}^4\right).$

This implies that the mean radiant power of reflected radiation of the surrounding objects at the object can be eliminated from the thermodynamic model by knowing the temperature of the blackbody radiator section, sensory detection of the blackbody radiator section and the reflector section.

Through these assumptions, the absolute temperature, surface temperature of the person two can be determined as $T=\sqrt[4]{\frac{e_{cal}}{\tau e}}{\mathrm{<figure-callout\; id="4"\; label="T\; M"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">T</figure-callout>}}_M^{}-\frac{1-e}{e}\left({\mathrm{<figure-callout\; id="4"\; label="T\; B\; B"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">T</figure-callout>}}_{BB}^{}+\frac{e_{cal}}{{\tau }_{BB}}\left(T_M{}_{,\mathrm{<figure-callout\; id="4"\; label="R"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">R</figure-callout>}}^4-T_M{}_{,BB}^4\right)\right)-\frac{1-\tau }{\tau e\left(1-{\tau }_{BB}\right)}\left(e_{cal}{T}_M{}_{,\mathrm{<figure-callout\; id="4"\; label="B\; B"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">B</figure-callout>}B}^4-{\tau }_{BB}{T}_{BB}^4\right).$

erhält man eine lineare Abhängigkeit der Form $T_{M,BB}^4=a{T}_{BB}^4+b,$

wobei $a=\frac{{\tau }_{BB}}{{\epsilon }_{cal}}$

und $b=\frac{1-{\tau }_{BB}}{{\epsilon }_{cal}}{T}_A^4.$

Durch die Verwendung von diskreten Werten für T_BB,i und d_BB,j ein zweidimensionales Array von Temperaturmessungen der Form $T_{M,BB,ij}^4=a_j{T}_{BB,i}^4+b_j.$

The quantity ε _cal and the transmission τ(d) can be determined by a plurality of measurements of the blackbody radiator section for different temperatures of the blackbody radiator section T _BB,i and different distances d _BB,j . By rearranging the equation for $e_{cal}{T}_{M,\mathrm{<figure-callout\; id="4"\; label="B\; B"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">B</figure-callout>}B}^4$

one obtains a linear dependence of the shape $T_{M,BB}^4=a{T}_{BB}^4+b,$

whereby $a=\frac{{\tau }_{BB}}{e_{cal}}$

and $b=\frac{1-{\tau }_{BB}}{e_{ca\mathrm{<figure-callout\; id="4"\; label="l\; T\; A"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">l</figure-callout>}}}{T}_A^{}{}_4^{}.$

By using discrete values for T _BB,i and d _{BB,j ,} a two-dimensional array of mold temperature measurements $T_{M,BB,i\mathrm{<figure-callout\; id="4"\; label="j"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">j</figure-callout>}}^4=a_j{T}_{BB,\mathrm{<figure-callout\; id="4"\; label="i"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">i</figure-callout>}}^4+b_j.$

The value a _j can be determined from the distances d _BB,j from a fit of the measurement pairs {(T _BB,i ⁴ _; T _M,BBij ⁴ )}. Using the smallest possible distance d, the current emissivity of the thermal sensor with τ = 1 can be determined as ∈ _cal = 1/a ₀ . The change in transmittance with distance die is available from a fit of the form τ _BB,j = a _j /a ₀ . Assuming an exponential behavior of the transmittance, this can be described as τ = e ^-βd , where β can be determined from the measurement pairs (d _BB , _i , In τ _BB,j ). For example, one obtains from the literature value $\tau \left(2m\right)=0.9\text{f}\ddot{\text{and}}\text{right}\beta =-\frac{\text{ln}0.9}{2m}.$

To determine the minimum temperature difference between core and surface ΔT _C,S,min , the relationship ΔT _C,S,min = ΔT _C,S,min,RT + ΔT _{C,S,SO is} assumed, where ΔT _C,S,SO describes the scene-specific temperature difference.

The first part of this equation, the constant room temperature fraction, can be taken from the literature or determined by laboratory experiments. The second part must be determined for the arrangement. This is done by detecting the shielding section using sensors. The shield section, or shield, is optionally separated from the blackbody section by a narrow air-filled gap. T _BB - _{BB .DELTA.T, Sh} = T _Sh applies to the temperature difference between black body portion and shielding. The approximation described above results in ΔT _BB,Sh = ΔT _BB,Sh,RT + ΔT _BB,Sh,SO . With a suitable choice of the shielding material, in particular the choice that the emissivity and/or the thermal conductivity are similar to human skin, as well as dimensioning the layer thickness, that applies ΔT _BB,Sh,RT ≈ ΔT _C,S,min,RT , for the the quantity sought is assumed to be ΔT _C,S,SO = f(ΔT _BB,Sh,SO ) . First-order linear approximation gives ΔT _C,S,SO = γΔT _BB,Sh,SO . The value y can be determined experimentally from measurements, for example for different air temperatures and/or air flows. The core temperature of the person is then T _C = T _S,max - (ΔT _C,S,min,RT + ΔT _C,S,SO ). Substituting ΔT _C,S,SO gives T _C = T _S,max - ΔT _C,S,min,RT - γΔT _BB,SH,SO .

wobei ε_S der Emissionsgrad der Haut ist. $$\begin{array}{l}{T}_{Sh}=\\ \sqrt[4]{\frac{{\epsilon }_{cal}}{{\tau }_{Sh}{\epsilon }_{Sh}}{T}_{M,Sh}^4-\frac{1-{\epsilon }_{Sh}}{{\epsilon }_{Sh}}\left(T_{BB}^4+\frac{{\epsilon }_{cal}}{{\tau }_{BB}}\left(T_M{}_{,R}^4-T_M{}_{,BB}^4\right)\right)-\frac{1-{\tau }_{Sh}}{{\tau }_{Sh}{\epsilon }_{Sh}\left(1-{\tau }_{BB}\right)}({\epsilon }_{cal}{T}_M{}_{,BB}^4-{\tau }_{BB}{T}_{BB}^4}\end{array}$$

, wobei ε_Sh Emissionsgrad der Abschirmung ist. Durch Vereinfachung ergibt sich: $$T_{Sh}=\sqrt[4]{\frac{{\epsilon }_{cal}}{{\tau }_{Sh}{\epsilon }_{Sh}}{T}_{M,Sh}^4-\frac{1-{\epsilon }_{Sh}}{{\epsilon }_{Sh}}\left(T_{BB}^4+\frac{{\epsilon }_{cal}}{{\tau }_{BB}}\left(T_M{}_{,R}^4-T_M{}_{,BB}^4\right)\right)-\frac{1}{{\tau }_{BB}{\epsilon }_{Sh}}({\epsilon }_{cal}{T}_M{}_{,BB}^4-{\tau }_{BB}{T}_{BB}^4}$$

For the quantities we are looking for, this results in: $$\begin{array}{l}{T}_{S,max}=\\ \sqrt[4]{\frac{e_{cal}}{{\tau }_S{e}_S}{T}_{M,S,ma\mathrm{<figure-callout\; id="4"\; label="x"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">x</figure-callout>}}^4-\frac{1-e_S}{e_S}\left({\mathrm{<figure-callout\; id="4"\; label="T\; B\; B"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">T</figure-callout>}}_{BB}^{}+\frac{e_{cal}}{{\tau }_{BB}}\left(T_M{}_{,\mathrm{<figure-callout\; id="4"\; label="R"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">R</figure-callout>}}^4-T_M{}_{,BB}^4\right)\right)-\frac{1-{\tau }_S}{{\tau }_S{e}_S\left(1-{\tau }_{BB}\right)}\left(e_{cal}{T}_M{}_{,\mathrm{<figure-callout\; id="4"\; label="B\; B"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">B</figure-callout>}B}^4-{\tau }_{BB}{T}_{BB}^4\right)}\end{array}$$

where ε _{S is} the emissivity of the skin. $$\begin{array}{l}{T}_{SH}=\\ \sqrt[4]{\frac{e_{cal}}{{\tau }_{SH}{e}_{SH}}{T}_{M,\mathrm{<figure-callout\; id="4"\; label="S\; H"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">S</figure-callout>}H}^4-\frac{1-e_{SH}}{e_{SH}}\left({\mathrm{<figure-callout\; id="4"\; label="T\; B\; B"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">T</figure-callout>}}_{BB}^{}+\frac{e_{cal}}{{\tau }_{BB}}\left(T_M{}_{,\mathrm{<figure-callout\; id="4"\; label="R"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">R</figure-callout>}}^4-T_M{}_{,BB}^4\right)\right)-\frac{1-{\tau }_{SH}}{{\tau }_{SH}{e}_{SH}\left(1-{\tau }_{BB}\right)}(e_{cal}{T}_M{}_{,\mathrm{<figure-callout\; id="4"\; label="B\; B"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">B</figure-callout>}B}^4-{\tau }_{BB}{\mathrm{<figure-callout\; id="4"\; label="T\; B\; B"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">T</figure-callout>}}_{BB}^{}}\end{array}$$

, where ε _{Sh is the} emissivity of the shield. By simplification we get: $$T_{SH}=\sqrt[4]{\frac{e_{cal}}{{\tau }_{SH}{e}_{SH}}{T}_{M,\mathrm{<figure-callout\; id="4"\; label="S\; H"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">S</figure-callout>}H}^4-\frac{1-e_{SH}}{e_{SH}}\left({\mathrm{<figure-callout\; id="4"\; label="T\; B\; B"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">T</figure-callout>}}_{BB}^{}+\frac{e_{cal}}{{\tau }_{BB}}\left(T_M{}_{,\mathrm{<figure-callout\; id="4"\; label="R"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">R</figure-callout>}}^4-T_M{}_{,BB}^4\right)\right)-\frac{1}{{\tau }_{BB}{e}_{SH}}(e_{cal}{T}_M{}_{,\mathrm{<figure-callout\; id="4"\; label="B\; B"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">B</figure-callout>}B}^4-{\tau }_{BB}{\mathrm{<figure-callout\; id="4"\; label="T\; B\; B"\; filenames="DE102020208813A1\_0016.png"\; state="\{\{state\}\}">T</figure-callout>}}_{BB}^{}}$$

QUOTES INCLUDED IN DESCRIPTION

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Patent Literature Cited

• DE 102014226342 A1 [0003]

Claims (14)

Method for determining a temperature of a person (2) in a monitored area (3), wherein the monitoring area (3) is detected by a thermal sensor (4) and sensor data are provided by the thermal sensor (4), wherein the person (2) and a black body emitter (5) are arranged in the monitored area (3) detected by sensors, wherein the sensor data comprises a first radiant power and a second radiant power, the first radiant power forming a thermal radiant power of a section of a person detected by the thermal sensor (4), the second radiant power forming a thermal radiant power of a blackbody radiator section (9) detected by the thermal sensor (4), wherein the temperature of the person (2) is determined based on the first and second radiant power. procedure after claim 1 , characterized in that the temperature of the person (2) is determined based on a thermodynamic model, wherein according to the thermodynamic model a thermal radiation power that can be detected by the thermal sensor (4) comprises a personal radiation power component and an environmental radiation power component, the environmental radiation power component being based on the second radiation power is determined. procedure after claim 1 or 2 , characterized in that a core temperature of the person (2) is determined, the core temperature being determined based on a difference in a surface temperature and a core-surface temperature difference. procedure after claim 3 , characterized in that the core temperature is determined based on a maximum surface temperature and/or a minimum core-surface temperature difference. Procedure according to one of claims 3 or 4 , characterized in that face recognition is applied to the sensor data to determine the maximum surface temperature, with a section of the face being selected as the maximum surface temperature. Method according to one of the preceding claims, characterized in that air radiation power is taken into account to determine the temperature of the person (2) and/or the ambient radiation power component includes the air radiation component, the air radiation power and/or an associated air temperature being based on the radiation power of the blackbody radiator section (9 ) and a measured and/or controlled blackbody portion temperature. Method according to one of the preceding claims, characterized in that to determine the temperature of the person (2) an average reflected radiant power is taken into account and / or the ambient radiant power component comprises the average reflected radiant power, wherein the black body radiator (5) has a reflective reflector section (15), wherein the sensor data comprise a reflector radiant power, the reflector radiant power forming a thermal radiant power of the reflector section (15) detected by the thermal sensor (4), the average reflected radiant power and/or an associated average reflection temperature based on the reflector radiant power, the radiant power of the blackbody radiator section (9) and a measured and/or controlled blackbody portion temperature. Method according to one of the preceding claims, characterized in that to determine the temperature of the person (9) a transmittance of the air and / or a calibration emissivity of the thermal sensor (4) is taken into account, the transmittance and / or the calibration emissivity based on a characteristic and /or a series of measurements is determined, the characteristic curve and/or series of measurements comprising measured thermal radiation powers of the blackbody radiator section (9) at different blackbody section temperatures and/or different thermal sensor-blackbody distances. Method according to one of the preceding claims, characterized in that the core-surface temperature difference forms a sum of a constant core-surface temperature difference and a scene-dependent core-surface temperature difference offset. procedure after claim 9 , characterized in that the blackbody radiator has a shielding portion (14), wherein in the shielding portion (14) a shield (11) covers a surface of the blackbody portion (9), wherein the sensor data includes a shielding radiation power, the shielding radiation power being a thermal sensor (4th ) detected thermal radiation power of the shield section (14), wherein the scene-dependent core-surface temperature difference offset is determined based on the shield radiation power. Method according to one of the preceding claims, characterized in that the determination of the core temperature is based on a measured and/or set temperature of the blackbody radiator section (9), a measured and/or set temperature of the refector section (15), a measured and/or set temperature of the shielding section (14), the first radiant power, the second radiant power, the reflector radiant power and the shield radiant power. Computer program for execution on a computer, wherein the computer program is designed to carry out the method according to one of the preceding claims when the computer program is executed. Measuring arrangement comprising a thermal sensor for detecting a monitored area (3) and for providing sensor data comprising first and second radiation power levels, with a blackbody radiator (5) and a person (2) being arranged in the monitored area, with the first radiation power being a radiation power of a section of a person and the second radiant power comprises a radiant power of a blackbody radiator section (9), with an evaluation device, wherein the evaluation device is designed to determine the temperature of the person (2) based on the first and second radiant power. Black body radiator (5) comprising a black body radiator section (9), a reflector section (15) and a shielding section (14).

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