Identification device, identification method, and recording medium with recorded identification program

1. An identification device comprising:

at least one memory storing instructions; and

at least one processor connected to the at least one memory and configured to execute the instructions to:

measure pulse-wave information;

generate factor information by using the measured pulse-wave information and estimated pulse-wave information; and

identify an identification target based on the generated factor information, wherein

the at least one processor is configured to execute the instructions to calculate the estimated pulse-wave information based on biological model information represented by equation 1 and equation 2, wherein

the equation 1 is expressed by

X t =( x t ,θ t )= g ( x t-1 ,θ t )+ v t , and

the equation 2 is expressed by

y t =h ( x t )+ w t , wherein

t represents a timing,

x t represents a state of the biological subject at a timing t,

y t represents measurement information measured in relation to the identification target,

θ t represents a value of a parameter used in calculating a state at the timing t from a state at a timing (t−1),

v t represents an error relating to process g, and

w t represents an error relating to process h.

2. The identification device according to claim 1 , wherein

the factor information is a parameter that expresses a relationship between states of an biological subject at a plurality of timings.

3. The identification device according to claim 1 , wherein

the process g in the equation 1 represents a process of finding a state at a second timing from a state at a first timing, and

the at least one processor is configured to execute the instructions to generate the factor information based on the value of the parameter θ t in the equation 1.

4. The identification device according to claim 3 , wherein

the process g in the equation 1 is a process of solving equation 3 with respect to a variable x, wherein

the equation 3 is expressed by

m

⁢

d

2

⁢

x

dt

2

=

-

kx

-

c

⁢

dx

dt

+

F

,

wherein

m represents a volume of blood flow,

k represents blood vessel resistance,

c represents blood viscosity,

F represents force applied to the blood vessels.

5. The identification device according to claim 1 , wherein

the factor information is information regarding a change in blood inside blood vessels of the identification target.

6. The identification device according to claim 1 , wherein

the factor information is at least one of parameters calculated according to a model estimation process, in which a value of the parameter θ t is obtained for each of a plurality of timings according to a data assimilation process to reduce an error between the measurement information y t calculated according to the processes g and h of the equations 1 and 2 and the measured pulse-wave information, and

the at least one processor is configured to execute the instructions to:

calculate the value of the parameter θ t , as the factor information, in accordance with the data assimilation process, along with the model estimation process acquired in relation to each timing so as to reduce the error between the measurement information y t calculated according to the processes g and h of the equations 1 and 2, and the measured pulse-wave information;

select certain list information satisfying a predetermined determination criterion of the generated factor information out of list information associating the factor information of the biological subject to be the identification target with identification information for identifying the biological subject; and

identify the identification information in the selected certain list information.

7. The identification device according to claim 6 , wherein

the list information includes information representing a kind of medicine taken at measuring of the pulse wave of the biological subject, and

the at least one processor is configured to execute the instructions to identify the certain list information based on information representing a kind of medicine taken by the identification target and the generated factor information.

8. The identification device according to claim 6 , wherein

the list information includes information representing a volume of water taken at measuring of the pulse wave of the biological subject, and

the at least one processor is configured to execute the instructions to identify the certain list information based on information representing a volume of water taken by the identification target and the generated factor information.

9. The identification device according to claim 6 , wherein

the list information includes information representing a movement of the biological subject at measuring of the pulse wave of the biological subject, and

the at least one processor is configured to execute the instructions to identify the certain list information based on information representing a movement of the identification target and the generated factor information.

10. The identification device according to claim 6 , wherein

the factor information in the list information is generated for the pulse-wave information measured during pressuring of the biological subject, and

the measured pulse-wave information for the identification target is measured during pressuring of the identification target.

11. An identification device comprising:

at least one memory storing instructions; and

at least one processor connected to the at least one memory and configured to execute the instructions to:

measure pulse-wave information; generate factor information based on an ejection wave included in the pulse-wave information and a reflected wave corresponding to the ejection wave; and

identify an identification target based on the generated factor information, wherein

the at least one processor is configured to execute the instructions to calculate the estimated pulse-wave information based on biological model information represented by equation 1 and equation 2, wherein

the equation 1 is expressed by

X t =( x t ,θ t )= g ( x t-1 ,θ t )+ v t , and

the equation 2 is expressed by

y t =h ( x t )+ w t , wherein

t represents a timing,

xt represents a state of the biological subject at a timing t,

yt represents measurement information measured in relation to the identification target,

θt represents a value of a parameter used in calculating a state at the timing t from a state at a timing (t−1),

vt represents an error relating to process g, and

wt represents an error relating to process h.

12. The identification device according to claim 11 , wherein

the factor information is time difference information representing a time difference between the ejection wave and the reflected wave.

13. A non-transitory recording medium storing a program for causing a computer to execute processing of:

measuring pulse-wave information;

generating factor information by using the measured pulse-wave information and estimated pulse-wave information;

identifying an identification target based on the generated factor information; and

calculating the estimated pulse-wave information based on biological model information represented by equation 1 and equation 2, wherein

the equation 1 is expressed by

X t =( x t ,θ t )= g ( x t-1 ,θ t )+ v t , and

the equation 2 is expressed by

y t =h ( x t )+ w t , wherein

t represents a timing,

x t represents a state of the biological subject at a timing t,

y t represents measurement information measured in relation to the identification target,

θ t represents a value of a parameter used in calculating a state at the timing t from a state at a timing (t−1),

v t represents an error relating to process g, and

w t represents an error relating to process h.