Control device for internal combustion engine and control program therefor

1. A control device for an internal combustion engine, the control device comprising:

an information acquirer configured to acquire, from a state amount sensor, information on a state amount that changes depending on an operation state of the internal combustion engine; and

a computing unit configured to compute at least one control amount for controlling the internal combustion engine based on the information acquired by the information acquirer,

the computing unit including:

a region determiner configured to determine whether the state amount falls within a set region;

a first computing unit configured to use at least one in-region state amount, which is the state amount determined to fall within the set region, as an input value to compute the at least one control amount by a neural network; and

a second computing unit configured to use at least one out-of-region state amount, which is the state amount determined to fall out of the set region, as an input value to compute the at least one control amount, and

the second computing unit being configured to:

select at least one reference state amount, which is the state amount that falls within the set region, based on the at least one out-of-region state amount;

use the at least one reference state amount as an input value to compute at least one reference control amount by the neural network; and

compute the at least one control amount corresponding to the at least one out-of-region state amount based on the at least one reference control amount.

2. The control device for the internal combustion engine according to claim 1 , wherein the second computing unit is configured to select the state amount closest to the at least one out-of-region state amount as the at least one reference state amount.

3. The control device for the internal combustion engine according to claim 2 ,

wherein the at least one in-region state amount includes a plurality of in-region state amounts and

wherein the second computing unit is configured to select, from among the plurality of in-region state amounts, a state amount having a shortest distance from the at least one out-of-region state amount as the at least one reference state amount in an n-dimensional space having coordinate axes each representing the state amount.

4. The control device for the internal combustion engine according to claim 3 , wherein the second computing unit is configured to output the at least one reference control amount directly as the at least one control amount corresponding to the at least one out-of-region state amount.

5. The control device for the internal combustion engine according to claim 3 ,

wherein the at least one in-region state amount includes a plurality of in-region state amounts and

wherein the second computing unit is configured to:

compute at least one linear function that passes through the at least one out-of-region state amount and a specific state amount among the plurality of in-region state amounts;

select, as the at least one reference state amount, the specific state amount and a state amount on the at least one linear function other than the specific state amount;

use the specific state amount and the state amount on the at least one linear function other than the specific state amount as input values to compute the at least one reference control amount by the neural network; and

compute at least one approximate function being a function for approximating the at least one reference control amount, and substitute the at least one out-of-region state amount into the at least one approximate function, to thereby compute the at least one control amount corresponding to the at least one out-of-region state amount.

6. The control device for the internal combustion engine according to claim 2 , wherein the second computing unit is configured to output the at least one reference control amount directly as the at least one control amount corresponding to the at least one out-of-region state amount.

7. The control device for the internal combustion engine according to claim 2 ,

wherein the at least one in-region state amount includes a plurality of in-region state amounts and

wherein the second computing unit is configured to:

compute at least one linear function that passes through the at least one out-of-region state amount and a specific state amount among the plurality of in-region state amounts;

select, as the at least one reference state amount, the specific state amount and a state amount on the at least one linear function other than the specific state amount;

use the specific state amount and the state amount on the at least one linear function other than the specific state amount as input values to compute the at least one reference control amount by the neural network; and

compute at least one approximate function being a function for approximating the at least one reference control amount, and substitute the at least one out-of-region state amount into the at least one approximate function, to thereby compute the at least one control amount corresponding to the at least one out-of-region state amount.

8. The control device for the internal combustion engine according to claim 1 , wherein the second computing unit is configured to output the at least one reference control amount directly as the at least one control amount corresponding to the at least one out-of-region state amount.

9. The control device for the internal combustion engine according to claim 1 ,

wherein the at least one in-region state amount includes a plurality of in-region state amounts and

wherein the second computing unit is configured to:

compute at least one linear function that passes through the at least one out-of-region state amount and a specific state amount among the plurality of in-region state amounts;

select, as the at least one reference state amount, the specific state amount and a state amount on the at least one linear function other than the specific state amount;

use the specific state amount and the state amount on the at least one linear function other than the specific state amount as input values to compute the at least one reference control amount by the neural network; and

compute at least one approximate function being a function for approximating the at least one reference control amount, and substitute the at least one out-of-region state amount into the at least one approximate function, to thereby compute the at least one control amount corresponding to the at least one out-of-region state amount.

10. The control device for the internal combustion engine according to claim 9 ,

wherein the at least one linear function includes a plurality of linear functions; the at least one approximate function includes a plurality of approximate functions; the at least one reference control amount includes a plurality of reference control amounts; and the at least one control amount includes a plurality of control amounts and

wherein the second computing unit is configured to compute the plurality of linear functions, compute the plurality of approximate functions, compute the plurality of reference control amounts, compute the plurality of control amounts corresponding to the at least one out-of-region state amount, and statistically compute the computed plurality of control amounts.

11. The control device for the internal combustion engine according to claim 1 , wherein the set region is set as a region in which a density of presence of training input data to be used for learning by the neural network is equal to or higher than a reference density in an n-dimensional space having coordinate axes each representing the state amount.

12. A control program for an internal combustion engine, which is executed by a computer to perform:

information acquisition processing of acquiring, from a state amount sensor, information on a state amount that changes depending on an operation state of the internal combustion engine; and

computation processing of computing a control amount for controlling the internal combustion engine based on the information acquired by the information acquisition processing,

the computation processing including:

region determination processing of determining whether the state amount falls within a set region;

first computation processing of using an in-region state amount, which is the state amount determined to fall within the set region, as an input value to compute the control amount by a neural network; and

second computation processing of using an out-of-region state amount, which is the state amount determined to fall out of the set region, as an input value to compute the control amount, and

the second computation processing including processing of:

selecting a reference state amount, which is the state amount that falls within the set region, based on the out-of-region state amount;

using the reference state amount as an input value to compute a reference control amount by the neural network; and

computing the control amount corresponding to the out-of-region state amount based on the reference control amount.