CONTROL DEVICE OF AFTER-TREATMENT SYSTEM, AFTER-TREATMENT SYSTEM, METHOD OF CONTROLLING AFTER-TREATMENT SYSTEM, AND COMPUTER PROGRAM

In an after-treatment system configured to convert a harmful substance in exhaust emission using an additive, an object is to allow for supply of the additive by taking into account a variation in a supply portion serving to supply the additive.There is provided a control device of an after-treatment system, comprising: an outlet concentration acquirer configured to obtain a concentration of a harmful substance at an outlet of a main flow path; a first estimator configured to estimate a first adsorption amount that is an adsorption amount of an additive adsorbed to a catalyst, by using a mathematical model; a second estimator configured to estimate a second adsorption amount that is an adsorption amount of the additive in the catalyst in consideration of the concentration of the harmful substance obtained by the outlet concentration acquirer, and a gain value that indicates a variation in a supply portion in consideration of the concentration of the harmful substance obtained by the outlet concentration acquirer, from the first adsorption amount and a gain value indicating a variation in the supply portion, by using a state estimation theory; and a supply controller configured to control supply of the additive in the supply portion by using the second adsorption amount and the gain value estimated by the second estimator.