An exhaust gas aftertreatment system includes: a first sensor configured to measure a parameter in the exhaust gas aftertreatment system; a second sensor configured to measure the parameter in the exhaust gas aftertreatment system, the second sensor disposed proximate the first sensor; and at least one controller configured to alternately receive sensor values from the first sensor for a first target period of time, and receive sensor values from the second sensor for a second target period of time.

Systems and methods for optimizing a performance variable for an engine system. The method includes applying constraints of manipulated variables as well as performance variables, mechanical constraints and other engine responses to response models. The response models each represent a piecewise linear relationship between the manipulated variables and other engine responses including performance variables and constraints. The method also comprises determining an optimal target for each of the manipulated variables by using a quasi-simplex optimization process on the response models. The optimal targets of the manipulated variables correspond to an optimal value of the performance variable.

In a control apparatus, a heater adjuster performs a regeneration task of causing a heater to heat a sensing member of a particulate matter sensor to burn particulate matter deposited on the sensing member to thereby remove the particulate matter from the sensing member. The heater adjuster performs a deposition reduction task of maintaining, for a predetermined duration, a temperature of the sensing member at a deposition reduction temperature that reduces additional particulate-matter deposition on the sensing member. The predetermined duration is defined from completion of a regeneration task to a time when an environmental condition around the particulate matter sensor is determined to be stable. The heater adjuster stops the heater from heating the sensing member if a condition determiner determines that the environmental condition around the particulate matter sensor is stable.

A system includes an aftertreatment system coupled to an engine, a heater, at least one sensor configured to determine an exhaust gas temperature, and a processing circuit. The processing circuit is structured to determine whether the exhaust gas temperature is at or below a predefined threshold temperature; provide a first command to control the heater in response to the exhaust gas temperature being at or below the predefined threshold temperature; selectively provide a second command to increase the exhaust gas temperature; and coordinate the first and second commands, where the first command is provided followed by the second command only if the predefined threshold temperature is not attained by the first command.

A method for controlling an SCR catalytic converter (20, 30), comprising detecting (200) concentration values (314, 324; 414, 424) in the exhaust gas downstream of the catalytic converter (20), wherein at least one concentration value for NH.sub.3 and one concentration value for NO.sub.x is detected; calculating (202) modeled concentration values (316, 322; 416, 422) for NH.sub.3 and NO.sub.x downstream of the catalytic converter on the basis of a catalytic converter model, wherein the model comprises an aging parameter (342, 442) which at least partially describes aging of the modeled catalytic converter; comparing (208) the detected concentration values with the modeled concentration values; and, in a manner dependent on the result of the comparison, changing the aging parameter (342, 442) of the model and/or changing a predefined dosing quantity for a reducing agent in the SCR catalytic converter.

A method includes providing electric power to an exhaust aftertreatment system component, where the exhaust aftertreatment system component is one of a particulate filter and an electrically heated catalyst. The method includes obtaining an impedance value of the exhaust aftertreatment system component in response to providing the electric power. The method includes determining a structural state of the exhaust aftertreatment system component based on the impedance value.

An exhaust gas aftertreatment system for an internal combustion engine comprises an exhaust gas system with an exhaust gas channel in which at least two exhaust gas aftertreatment components for the selective, catalytic reduction of nitrogen oxides are arranged. Downstream from the first exhaust gas aftertreatment component and upstream from the second exhaust gas aftertreatment component is a burner with which the exhaust gas can be heated up before it enters the second exhaust gas aftertreatment component. Downstream from the second exhaust gas aftertreatment component is an oxidation catalytic converter that converts unburned hydrocarbons. In a method for exhaust gas aftertreatment in an internal combustion engine having such an exhaust gas aftertreatment system, the exhaust gas from the internal combustion engine is heated up by the burner in order to heat up the second exhaust gas aftertreatment component for the selective, catalytic reduction of nitrogen oxides.

A selective catalytic reduction (SCR) system is provided for treating exhaust gas in an exhaust passage. The system comprises a hydrolysis catalyst located in the exhaust passage, and a diesel exhaust fluid (DEF) dosing unit configured to inject DEF onto the hydrolysis catalyst. A SCR catalyst is located in the passage downstream of the hydrolysis catalyst, and a controller controls DEF dosing by the dosing unit. The controller is configured to control the DEF dosing unit such that the DEF is injected at a modulated frequency of less than or equal to 1 Hertz. A method of treating exhaust gas in an exhaust passage using an SCR system is also provided.

A selective catalytic reduction system control system (10) and method of its use include an ammonia (“NH.sub.3”) slip sensor (13) located within an interior space (27) of an exhaust stack (15) of a selective catalytic reactor (31), toward an inlet end (25) of the stack (15); a housing (17) located within the interior space of the exhaust stack; the housing including face panels 19; a nitrogen oxides (“NOx”) sensor (11) contained within an interior space (29) defined by the face panels of the housing, at least two of the face panels (19.sub.I, 19.sub.O) containing an oxidation catalyst; and a dosing controller (59) in communication with the NH.sub.3 and NOx sensors, the dosing controller including a microprocessor with dosing logic embedded thereon. The housing with oxidation catalyst acts as a linear box, isolating the NOx sensor from NH.sub.3 slip, linearizing the NOx sensor signal.

An abnormality determination apparatus for an ammonia sensor is usable in an exhaust purification system including a catalyst, a supply apparatus, an ammonia sensor, an NO.sub.X sensor, and an oxygen sensor. During a continuation period within which ammonia supply to the catalyst continues after the supply apparatus stops supply of reductant, the abnormality determination apparatus calculates the ammonia concentration on a downstream side of the catalyst as a first concentration value, based on an output of the ammonia sensor and an output of the oxygen sensor. During the continuation period, the abnormality determination apparatus calculates the ammonia concentration on the downstream side of the catalyst as a second concentration value, based on an output of the NO.sub.X sensor and the output of the oxygen sensor. The abnormality determination apparatus determines presence or absence of abnormality in the ammonia sensor based on the first concentration value and the second concentration value.