Temperature estimation method, temperature estimation program and temperature estimation device
A temperature estimation apparatus includes a temperature calculation unit that calculates a core body temperature of a living body, a transient response detection unit that detects a starting point of time of transient response of the core body temperature, a correction section determination unit that determines a correction section of the core body temperature for each of a plurality of model functions that model a change in the core body temperature during a transient response, a temperature correction unit that calculates a result of correcting the core body temperature in the correction section using the plurality of model functions, a correction result evaluation unit that evaluates a correction result, and a correction result output unit that replaces data in the correction section among time-series data of the core body temperature with a correction result determined to be the best by the correction result evaluation unit.
1 . A temperature estimation method, the method comprising:
measuring a temperature of a surface of a test subject using a first temperature sensor;
measuring a temperature at a position away from the test subject using a second temperature sensor;
calculating an internal temperature of the test subject based on the temperature of the surface of the test subject and the temperature at the position away from the test subject;
detecting a starting point of time of a transient response of the internal temperature;
obtaining coefficients of each of a plurality of model functions that model a change in the internal temperature during the transient response for a part of a coefficient calculation section from the starting point of time of the transient response until a predetermined transient response convergence evaluation time elapses;
determining a correction section of the internal temperature for each of the plurality of model functions;
calculating results of correcting the internal temperature in the correction section using each of the plurality of model functions;
evaluating the results of correcting the internal temperature to determine a most preferred correction result from the results and select the correction section for the model function among the plurality of model functions that yielded the most preferred correction result; and
replacing data in the selected correction section among time-series data of the internal temperature with the most preferred correction result.
2 . The method according to claim 1 , wherein the plurality of model functions comprises:
a first model function that models a change in the internal temperature during the transient response in which wind blown to the test subject has changed; and
a second model function that models a change in the internal temperature during the transient response in which external air temperature has changed.
3 . The method according to claim 2 , wherein obtaining the coefficients of each of the plurality of model functions comprises obtaining the coefficient that minimizes a difference between the internal temperature and an output of the model function for each of the plurality of model functions.
4 . The method according to claim 3 , wherein the coefficient calculation section is a section from an intermediate value between a peak value of the internal temperature and the internal temperature at the starting point of time of the transient response to the peak value.
5 . The method according to claim 4 , wherein determining the correction section of the internal temperature for each of the plurality of model functions comprises:
obtaining a first approximate straight line of the internal temperature immediately before the starting point of time of the transient response and a second approximate straight line of the internal temperature from the starting point of time of the transient response until a transient response convergence evaluation time lapses; and
regarding each of the plurality of model functions, setting a section between two intersection points of the first and the second approximate straight lines and an output of the model function as the correction section.
6 . The method according to claim 5 , wherein evaluating the results of correcting the internal temperature comprises:
calculating an evaluation value for each of the results of correcting using the plurality of model functions; and
setting a minimum evaluation value as the most preferred correction result.
7 . The method according to claim 1 , wherein obtaining the coefficients of each of the plurality of model functions comprises obtaining the coefficient that minimizes a difference between the internal temperature and an output of the model function for each of the plurality of model functions.
8 . The method according to claim 1 , wherein the coefficient calculation section is a section from an intermediate value between a peak value of the internal temperature and the internal temperature at the starting point of time of the transient response to the peak value.
9 . The method according to claim 1 , wherein determining the correction section of the internal temperature for each of the plurality of model functions comprises:
obtaining a first approximate straight line of the internal temperature immediately before the starting point of time of the transient response and a second approximate straight line of the internal temperature from the starting point of time of the transient response until a transient response convergence evaluation time lapses; and
regarding each of the plurality of model functions, setting a section between two intersection points of the first and the second approximate straight lines and an output of the model function as the correction section.
10 . The method according to claim 1 , wherein evaluating the results of correcting the internal temperature comprises:
calculating an evaluation value for each of the results of correcting using the plurality of model functions; and
setting a minimum evaluation value as the most preferred correction result.
11 . A non-transitory computer-readable storage medium storing a temperature estimation program that, when executed by a computer, causes the computer to execute steps of:
calculating an internal temperature of a test subject based on a temperature of a surface of the test subject and a temperature at a position away from the test subject;
detecting a starting point of time of a transient response of the internal temperature;
obtaining coefficients of each of a plurality of model functions that model a change in the internal temperature during the transient response for a part of a coefficient calculation section from the starting point of time of the transient response until a predetermined transient response convergence evaluation time elapses;
determining a correction section of the internal temperature for each of the plurality of model functions;
calculating results of correcting the internal temperature in the correction section using each of the plurality of model functions;
evaluating the results of correcting the internal temperature to determine a most preferred correction result from the results and select the correction section for the model function among the plurality of model functions that yielded the most preferred correction result; and
replacing data in the selected correction section among time-series data of the internal temperature with the most preferred correction result.
12 . A temperature estimation apparatus, the apparatus comprising:
a first temperature sensor configured to measure a temperature of a surface of a test subject;
a second temperature sensor configured to measure a temperature at a position away from the test subject;
a temperature calculation circuit configured to calculate an internal temperature of the test subject based on the temperature of the surface of the test subject and the temperature at the position away from the test subject;
a transient response detection circuit configured to detect a starting point of time of a transient response of the internal temperature;
a coefficient calculation circuit configured to obtain coefficients of each of a plurality of model functions that model a change in the internal temperature during the transient response for a part of a coefficient calculation section from the starting point of time of the transient response until a predetermined transient response convergence evaluation time elapses;
a correction section determination circuit configured to determine a correction section of the internal temperature for each of the plurality of model functions;
a temperature correction circuit configured to calculate results of correcting the internal temperature in the correction section using each of the plurality of model functions;
a correction result evaluation circuit configured to evaluate the results of correcting the internal temperature from the temperature correction circuit to determine a most preferred correction result from the results and select the correction section for the model function among the plurality of model functions that yielded the most preferred correction result; and
a correction result output circuit configured to replace data in the selected correction section among time-series data of the internal temperature with the most preferred correction result.
13 . The apparatus according to claim 12 , wherein the plurality of model functions comprises:
a first model function that models a change in the internal temperature during the transient response in which wind blown to the test subject has changed; and
a second model function that models a change in the internal temperature during the transient response in which external air temperature has changed.
14 . The apparatus according to claim 12 , wherein, to obtain the coefficients of each of the plurality of model functions, the coefficient calculation circuit is configured to obtain the coefficient that minimizes a difference between the internal temperature and an output of the model function for each of the plurality of model functions.
15 . The apparatus according to claim 12 , wherein the coefficient calculation section is a section from an intermediate value between a peak value of the internal temperature and the internal temperature at the starting point of time of the transient response to the peak value.
16 . The apparatus according to claim 12 , wherein, to determine the correction section of the internal temperature for each of the plurality of model functions, the correction section determination circuit is configured to:
obtain a first approximate straight line of the internal temperature immediately before the starting point of time of the transient response and a second approximate straight line of the internal temperature from the starting point of time of the transient response until a transient response convergence evaluation time lapses; and
regarding each of the plurality of model functions, set a section between two intersection points of the first and the second approximate straight lines and an output of the model function as the correction section.
17 . The apparatus according to claim 12 , wherein, to evaluate the results of correcting the internal temperature, the correction result evaluation circuit is configured to:
calculate an evaluation value for each of the results of correcting using the plurality of model functions; and
set a minimum evaluation value as the most preferred correction result.