Patent Publication Number: US-11035310-B2

Title: Reference value engine control systems and methods

Description:
RELATED APPLICATIONS 
     The present application is a national phase filing under 35 U.S.C. § 371 of International Application No. PCT/US2015/055445, titled “REFERENCE VALUE ENGINE CONTROL SYSTEMS AND METHODS,” filed on Oct. 14, 2015, the entire disclosure of which being expressly incorporated herein by reference. 
     The present application discloses subject matter similar to the subject matter disclosed in the following applications: U.S. application Ser. No. 15/762,465, filed Mar. 22, 2018, which is a National Stage Entry of PCT/US2015/055447; U.S. application Ser. No. 15/762,469 filed Mar. 22, 2018, which is a National Stage Entry of PCT/US2015/055451; U.S. application Ser. No. 15/762,472 filed Mar. 22, 2018, which is a National Stage Entry of PCT/US2015/055452; and U.S. application Ser. No. 15/762,467 filed Mar. 22, 2018, which is a National Stage Entry of PCT/US2015/055448. 
     TECHNICAL FIELD 
     The present disclosure relates generally to internal combustion engines. In particular, the disclosure relates to control of internal combustion engines using subsystem target values. 
     BACKGROUND 
     Engine systems including internal combustion engines are often required to meet performance in several areas. While delivering requested amounts of power, engines are also often required to operate efficiently in terms of resource consumption and meet low emission requirements, such as EPA Tier 4 Final requirements for smoke and NO X  emissions. These goals are often governed by trade-offs, such as targeting greater power delivery while also targeting less fuel consumption. The design of the engine system often includes one or more subsystems to balance, or optimize, these performance requirements. For example, a subsystem may be a fuel system, an air handling system, and an aftertreatment system. Engine systems are often calibrated to meet performance requirements under varying conditions, such as during steady state versus transient state, or at various altitudes. With increasing performance requirements, there remains a continuing need to robustly calibrate and operate engine systems to provide power with minimal resource consumption while meeting emissions requirements. 
     SUMMARY 
     Aspects of various embodiments relate to a method comprising: interpreting a basis variable set, the basis variable set including an engine speed, a commanded fueling value, an in-cylinder oxygen concentration value, and oxygen-to-fuel ratio value; determining a reference value set in response to the basis variable set and a fuel controller specification set, wherein the reference value set includes a start-of-injection command; and providing the reference value set to a fuel control commander. The reference value set optionally includes a rail pressure command. 
     Some embodiments relate to an apparatus comprising: a combustion parameter definer structured to interpret a basis variable set, the basis variable set including an engine speed, a commanded fueling value, and an in-cylinder oxygen concentration value; a fueling target determiner structured to determine a reference value set in response to the basis variable set and a fuel controller specification set, wherein the reference value set includes a start-of-injection command; and a fuel control circuit structured to provide at least one fueling command value in response to the reference value set. 
     Further embodiments relate to an engine system, comprising an internal combustion engine; a controller; and a fuel system in operative communication with the engine and the controller, the fuel system structured to provide fuel to the engine in response to the at least one fueling command value. The controller is configured to interpret a basis variable set, the basis variable set including an engine speed, a commanded fueling value, and an in-cylinder oxygen concentration value; determine a reference value set in response to the basis variable set and a fuel controller specification set, wherein the reference value set includes a start-of-injection command; and provide at least one fueling command value in response to the reference value set. 
     Aspects of various embodiments relate to a method, comprising: interpreting a basis variable set, the basis variable set including a predicted engine speed trajectory, a predicted fueling trajectory, and an ambient value; determining a reference value set in response to the basis variable set and an air handling controller specification set, wherein the reference value set includes a mass charge flow (MCF) value; and providing the reference value set to an air handling control commander. 
     The method optionally further comprises determining a steady state reference value set in response to the basis variable set and the air handling controller specification set; and providing the steady state reference value set as an initial design reference value set. Yet further, the method optionally comprises interpreting a threshold criteria set, wherein the threshold criteria set includes at least one of an objective value subset and a constraint value subset; checking for a threshold criteria violation in response to the predictive model output set and the threshold criteria set; and determining the reference value set further in response to the checking for the threshold criteria violation. Yet further still, the method optionally comprises constraining the design reference value set in response to a target BTE trajectory; and determining the reference value set further in response to the constrained design reference value set. 
     Some embodiments relate to an apparatus, comprising: an air handling parameter definer structured to interpret a basis variable set, the basis variable set including a predicted engine speed trajectory, a predicted fueling trajectory, and an ambient value; an air handling target determiner structured to determine a reference value set in response to the basis variable set and an air handling controller specification set, wherein the reference value set includes at least one of a mass charge flow value; and an air handling control circuit structured to provide at least one air handling command value in response to the reference value set. 
     Further embodiments relate to an engine system, comprising: an internal combustion engine; a controller; and an air handling system in operative communication with the engine and the controller, the air handling system structured to provide air to the engine in response to the at least one air handling command value. The controller is configured to interpret a basis variable set, the basis variable set including a predicted engine speed trajectory, a predicted fueling trajectory, and an ambient value; determine a reference value set in response to the basis variable set and an air handling controller specification set, wherein the reference value set includes at least one of a mass charge flow value and a pumping work target; and provide at least one air handling command value in response to the reference value set. 
     Aspects of various embodiments relate to a method, comprising: interpreting a basis variable set, the basis variable set including a space-velocity value, an exhaust related temperature, and an ambient value; determining a reference value set in response to the basis variable set and an aftertreatment controller specification set, wherein the reference value set includes at least one of a NO X  conversion efficiency value and a system out NO X  value; and providing the reference value set to an aftertreatment control commander. 
     The method optionally further comprises determining a steady state reference value set in response to the basis variable set and the aftertreatment controller specification set; providing the steady state reference value set as an initial design reference value set. Yet further, the method optionally comprises interpreting an aggregate emissions trajectory; constraining the design reference value set in response to the aggregate emissions trajectory and the predictive model output; and determining the reference value set further in response to the constrained design reference value set. 
     Some embodiments relate to an apparatus comprising: an aftertreatment parameter definer structured to interpret a basis variable set, the basis variable set including a space-velocity value, an exhaust related temperature, and an ambient value; an aftertreatment target determiner structured to determine a reference value set in response to the basis variable set and an aftertreatment controller specification set, wherein the reference value set includes at least one of a NO X  conversion efficiency value and a system out NO X  value; and an aftertreatment control circuit structured to provide at least one aftertreatment command value in response to the reference value set. 
     Further embodiments relate to an engine system comprising: an internal combustion engine; a controller; and an aftertreatment system in operative communication with the engine and the controller, the aftertreatment system structured to treat exhaust from the internal combustion engine in response to at least one aftertreatment command value. The controller is configured to interpret a basis variable set, the basis variable set including a space-velocity value, an exhaust related temperature, and an ambient value; determine a reference value set in response to the basis variable set and an aftertreatment controller specification set, wherein the reference value set includes at least one of a NO X  conversion efficiency value and a system out NO X  value; and provide at least one aftertreatment command value in response to the reference value set. 
     While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of an engine system including an internal combustion engine, according to some embodiments of the disclosure. 
         FIG. 2  is a schematic illustration of a processing subsystem of the engine system of  FIG. 1 , according to some embodiments. 
         FIG. 3  is a schematic flow diagram of an example procedure for controlling the fuel subsystem of  FIG. 1 , according to some embodiments. 
         FIG. 4  is a schematic illustration of a processing subsystem of the engine system of  FIG. 1  including a controller to perform certain operations to control the air handling system, according to some embodiments. 
         FIG. 5  is a schematic illustration of the air handling target determiner of the processing subsystem of  FIG. 4 , according to some embodiments. 
         FIG. 6  is a schematic illustration of an example predictive model of the air handling target determiner of  FIG. 5 , according to some embodiments. 
         FIG. 7  is a schematic flow chart diagram of an example procedure for controlling the air handling system of  FIG. 1 , according to some embodiments. 
         FIG. 8  is a schematic illustration of a processing subsystem of the engine system of  FIG. 1  including a controller to perform certain operations to control the aftertreatment system, according to some embodiments. 
         FIG. 9  is a schematic illustration of the aftertreatment target determiner of the processing subsystem of  FIG. 8 , according to some embodiments. 
         FIG. 10  is a schematic flow chart diagram of an example procedure for controlling the aftertreatment system of  FIG. 1 , according to some embodiments. 
     
    
    
     While the invention is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION 
       FIG. 1  is a schematic illustration of an engine system  100  utilizing reference values to control system performance, according to some embodiments of the disclosure. The system  100  cooperatively controls system components, such as subsystems, to provide engine performance within a specification or a requirement set of the system  100 . As shown, the system  100  includes an engine  105  and various subsystems, such as a fuel system  110 , an air handling system  115 , and an aftertreatment system  120 . An example system  100  includes a controller  125  (e.g., ECM) in operative communication with the engine  105 , which provides and receives signals related to various engine components, such as receiving measurement signals from sensors disposed in the engine  105  and providing control signals or commands to the subsystems. The controller  125  may also be in operative communication with other components of the system  100 , such as the subsystems  110 ,  115 ,  120 , in a similar manner. As used herein throughout, operative communication means an operative coupling by wire, wirelessly, mechanically, electronically, optically, magnetically, by network, et cetera, or any suitable combinations thereof. 
     The system  100  decouples the generation of target values from the generation of command values. For example, the system  100  generates one or more reference values in response to one or more basis variables. The one or more reference values are target values for a particular component&#39;s performance. Though many variables can affect a particular component&#39;s performance, one or more key basis variables are selected to characterize a majority of effects of the particular component. The key basis variables may be used for calibrating the reference values to respond to a variety of engine conditions, including steady state and transient state, while only calibrating for the engine  105  at steady state conditions and optionally a limited number of transient states. 
     In response to the one or more generated reference values, one or more commands are generated. The command values are calibrated to the particular component for which they are being generated. The commands can be provided to the particular component, which may reside, for example, in a subsystem. Utilizing key basis variables and decoupling target values from calibrated command values facilitates the time-efficient calibration of the system  100  and the potential for less-intensive processing-power to operate the system  100  while balancing and meeting performance in several areas. More detail of basis variables, reference values, and commands to facilitate these advantages are provided herein. 
     Turning now to provide more detail of the components of the system  100 , the fuel system  110  is in operative communication with the engine  105  and provides fuel for combustion. The fuel system  110  delivers a fueling amount at one or more specific times to one or more cylinders during each combustion cycle. In some embodiments, the fuel is fed through an injector directly into an engine cylinder, for example, when the engine  105  uses diesel fuel. In other embodiments, the fuel is mixed with air charge before entering an engine cylinder, for example, when the engine  105  uses gasoline or natural gas fuel. At least one physical component of the fuel system  110  is controlled by physical fuel controller  112 . The fuel controller  112  provides control signals to the physical components of the fuel system  110 , such as a fuel pressure pump and fuel injectors, in response to one or more fueling command values. 
     The air handling system  115  provides air to the engine  105  for combustion with fuel. An example air handling system  115  includes an air handling controller  117  in operative communication with one or more components of the air handling system to provide control signals to the physical air handling system components in response to one or more command values. As illustrated, the air handling system  115  includes an optional turbocharging system including at least one turbocharger, each including a compressor  130  and a turbine  135 . The turbocharging system receives exhaust and provides compressed air. In some embodiments, the compressor  130  is driven by the turbine  135  in a turbocharging configuration, wherein the compressor  130  is the air intake side of a turbocharger and the turbine  135  is the exhaust side of the turbocharger. In various embodiments, the turbocharging system of the air handling system  115  includes a waste gate  137  for bypassing the turbine  135  to control the speed of the turbine  135  and compressor  130 , for example, to avoid excessive speed. In other embodiments, the turbocharging system includes a variable geometry turbocharger (VGT), which facilitates controlling the speed of the turbine  135  and compressor  130 . 
     The example system includes a wastegate turbocharger. However, the airhandling system  115  may include any type of air handling system, including without limitation a naturally aspirated system, a fixed geometry turbocharger, a variable geometry turbocharger, a compressor bypass turbocharger, a dual turbocharger (series or parallel), and combinations thereof. 
     The system  100  includes a system air intake  140  into which air enters from the ambient environment. The air flows into and out of the compressor  130  to engine air intake  145 . The engine  105  may include an intake manifold operatively coupled to the engine air intake  145  to deliver the air to the intake ports of the cylinders. The system may include an intercooler, charger air cooler (not shown), and/or bypass systems therefore. After combustion, exhaust flows from the engine  105  to engine exhaust  150 . The engine  105  may include an exhaust manifold operatively coupled to the exhaust ports of the cylinders to collect the exhaust and direct the exhaust to the engine exhaust  150 . 
     Some of the exhaust is directed into an exhaust gas recirculation (EGR) system that is also part of the air handling system  115 . The EGR system directs a portion of the exhaust to EGR pathway  165  to engine air intake  145 . The EGR system may include an EGR valve  167  to control the flow (e.g., external EGR fraction) of exhaust gases back to the engine air intake  145 . The example EGR system is a high pressure EGR system having the EGR pathway  165  being coupled upstream of the turbine  135  and downstream of the compressor  130 . Some embodiments, alternatively or in addition, include a low pressure EGR system having the EGR pathway  165  being coupled downstream of the turbine  135  and upstream of the compressor  130 . The exhaust flows into and out of the turbine  135  to aftertreatment inlet  155 . 
     The example EGR system may additionally or alternatively include an EGR cooler (not shown) structured to cool the exhaust in the EGR pathway  165 . The EGR valve  167  may be positioned upstream (hotside) or downstream (coolside) of the EGR cooler. Where present, the EGR cooler may additionally be provided with a bypass valve. 
     The aftertreatment system  120  receives the exhaust from aftertreatment inlet  155  and at least a portion of the exhaust is expelled at the aftertreatment outlet  160 , which may also be referred to as the system outlet or tailpipe. The aftertreatment system  120  includes devices to treat emissions before exiting the tailpipe, such as one or more of a particulate filter or diesel particulate filter (DPF)  121 , a selective catalytic reduction (SCR) system  122  to chemically reduce components of the exhaust, a NO X  reductant fluid system  123  (e.g., a diesel exhaust fluid system) to provide NO X  reductant fluid to the exhaust, and an oxidation catalyst  126  to chemically oxidize components of the exhaust. The aftertreatment controller  124  is in operative communication with one or more of the aftertreatment components  121 ,  122 ,  123 ,  126  to provide control signals to at least one physical component of the aftertreatment system in response to one or more command values. The EGR system may also be considered part of the aftertreatment system  120 . 
     The controller  125  performs certain operations to control one or more subsystems of an internal combustion engine, such as one or more of a fuel system  110 , an air handling system  115 , and an aftertreatment system  120 . In certain embodiments, the controller  125  forms a portion of a processing subsystem including one or more computing devices having memory, processing, and communication hardware. The controller  125  may be a single device or a distributed device, and the functions of the controller may be performed by hardware and/or as computer instructions on a non-transient computer readable storage medium. 
     The logical relationship among the controllers and their functionality may be implemented in any known manner. Physical controllers  112 ,  117 , and  124  are shown as separate from controller  125  in  FIG. 1 . However, any number of these controllers may alternatively be implemented as part of controller  125 . For example, the controllers may be implemented in a single physical device, or in another example, as a distributed device. 
     In certain embodiments, the controller  125  includes one or more definers, determiners, commanders, and circuits that functionally execute the operations of the controller. The description herein including definers, determiners, commanders, and/or circuits emphasizes the structural independence of certain aspects of the controller  125 , and illustrates one grouping of operations and responsibilities of the controller. Other groupings that execute similar overall operations are understood within the scope of the present application. Definers, determiners, commanders, and/or circuits may be implemented in hardware and/or as computer instructions on a non-transient computer readable storage medium and may be distributed across various hardware or computer based components. 
     Example and non-limiting implementation elements include sensors providing any value determined herein, sensors providing any value that is a precursor to a value determined herein, datalink and/or network hardware including communication chips, oscillating crystals, communication links, cables, twisted pair wiring, coaxial wiring, shielded wiring, transmitters, receivers, and/or transceivers, logic circuits, hard-wired logic circuits, reconfigurable logic circuits in a particular non-transient state configured according to a specification, any actuator including at least an electrical, hydraulic, or pneumatic actuator, a solenoid, an op-amp, analog control elements (springs, filters, integrators, adders, dividers, gain elements), and/or digital control elements. 
       FIG. 2  is a schematic illustration of an example processing subsystem  200  including a controller  125  to perform certain operations to control the fuel subsystem  110 , according to some embodiments. The controller  125  includes one or more definers, determiners, commanders, and/or circuits such as a combustion parameter definer  202 , a fueling target determiner  204 , and a fueling commander  206 . The combustion parameter definer  202  interprets one or more basis variables for fueling. An example basis variable set  210  characterizes closed cycle efficiency (CCE), which considers the efficiency of combustion within the cylinder. The fueling target determiner  204  determines a fueling reference value set  226  in response to a key basis variable set  210  for fueling. An example reference value set  226  corresponds to target values for the fuel system  110 . Some target values are conformed to the specification set  211  of one or more physical controllers of the fuel system  110 . The fuel control commander  206  (e.g., a fuel control circuit) provides a fueling command set  252  including one or more fueling command values in response to a reference value set  226  for fueling. An example command value set  252  is optionally a modified version of the reference value set  226  due to limits or constraints (e.g., constraint value(s)  225 ) identified by the fuel control commander  206 . Further, the fuel system  110  may fuel the internal combustion engine  105  in response to the reference value set  226  upon receiving the one or more values of the fueling command set  252 . 
     Further embodiments of the controller  125  include an in-cylinder oxygen concentration ([O 2 ]) determiner  208  to provide an in-cylinder [O 2 ] value  216 , which may be included as a key basis variable. The in-cylinder oxygen determiner  208  interprets or determines an in-cylinder [O 2 ] value  216 . An example in-cylinder oxygen determiner  208  determines the in-cylinder [O 2 ] value  216  in response to one or more of a mass charge flow value  242  and an engine speed  212 . In additional embodiments, the in-cylinder [O 2 ] value  216  is determined further in response to one or more of an exhaust gas recirculation (EGR) fraction value  244  (e.g., internal or external EGR fraction), an exhaust manifold pressure (EMP) value  246 , an exhaust manifold temperature (EMT) value  248 . In yet further embodiments, the in-cylinder [O 2 ] value  216  is determined in response to one or more of an in-cylinder residual gas value  250  and an intake manifold oxygen fraction value  251 . 
     The example in-cylinder residual gas value  250  characterizes the amount of one or more gases already in the cylinder during intake (e.g., residual gases from the previous cycle). The example in-cylinder residual gas value  250  includes one or more of an oxygen value, a charge value, an exhaust value, or an air value. Such values may be, for example, an amount, a concentration, or a ratio. Exhaust may be a residual gas due to external EGR or internal EGR, for example. Internal EGR is the amount of exhaust gas left over in the cylinder from the previous combustion. 
     The present disclosure recognizes that an in-cylinder [O 2 ] value  216  may be measured directly or determined by a virtual sensor. The virtual sensor (e.g., implemented in the in-cylinder oxygen determiner  208 ) determines the in-cylinder oxygen concentration in response to one or more values related to air handling, which allows for an estimation of the oxygen concentration in the cylinder at the time of combustion. The selected values characterize the amount of oxygen entering the cylinder before intake valve closing and optionally the amount of gases already in the cylinder. Those having skill in the art, having the benefit of the disclosure herein and having a typical understanding of the particular system in view, would be able to select the appropriate values to determine the in-cylinder oxygen concentration. 
     In addition to the definers, determiners, commanders, and circuits, the controller  125  typically includes one or more parameters or data structures, such as values, variables, commands, and sets thereof. These parameters or data structures may be provided to, provided by, and used by any operational structures in the controller  125  (e.g., definers, determiners, commanders, or circuits). Further, some parameters or data structures are received by the controller  125  from a component external to the controller  125  or other source, which may be provided to and used by any of the operational structures. Some parameters or data structures may also be provided by the controller  125  to a component external to the controller  125  or other destination. Data structures may be provided to the controller  125  as sensor measurements, which may be physical measurements or virtual measurements. Virtual sensor measurements are determined or interpreted from sensor measurements and/or other data structures in the controller  125 . In some cases, virtual sensor measurements are the output of a definer, determiner, commander, or circuit of the controller  125 . 
     Certain operations described herein include operations to interpret and/or to determine one or more parameters or data structures. Interpreting or determining, as utilized herein, includes receiving values by any method known in the art, including at least receiving values from a datalink or network communication, receiving an electronic signal (e.g. a voltage, frequency, current, or PWM signal) indicative of the value, receiving a computer generated parameter indicative of the value, reading the value from a memory location on a non-transient computer readable storage medium, receiving the value as a run-time parameter by any means known in the art, and/or by receiving a value by which the interpreted parameter can be calculated, and/or by referencing a default value that is interpreted to be the parameter value. 
     Turning now to more detail of the definers, determiners, commanders, and circuits, as well as the parameters, the combustion parameter definer  202  interprets parameters and provides them to the controller  125 . Parameters of interest for combustion may include but are not limited to engine speed, engine torque, commanded fueling value (e.g., corresponding to requested torque), total fueling, in-cylinder gases, intake gases, cylinder temperature, rail pressure, and rail temperature. One or more sensors, actual or virtual, are utilized to interpret the parameters of interest, which may include but are not limited to an actual torque sensor, a revolutions per minute sensor, and a rail pressure sensor. The parameters provided may be used by another definer, determiner, commander, or circuit, or the parameters may be used by the combustion parameter definer  202  to provide a derived or calculated parameter. An example combustion parameter definer  202  interprets the engine speed  212  and the commanded fueling value  214  as inputs to the controller  125 . 
     As shown, the example controller  125  also includes a basis variable set  210 . An example basis variable set  210  includes engine speed  212 , commanded fueling value  214 , and an in-cylinder [O 2 ] value  216  (e.g., an in-cylinder oxygen concentration value at intake valve closing). The example basis variable set  210  is selected to characterize closed cycle efficiency (CCE) within the engine. As utilized herein, CCE represents the efficiency of the engine system after intake valve closing and before exhaust valve opening. Further embodiments of the basis variable set  210  include a trapped charge mass value  218 , an oxygen-to-fuel related value  220  (e.g., one or more of air-to-fuel ratio, charge-to-fuel ratio, and oxygen-to-fuel ratio), an in-cylinder temperature value  222  (e.g., temperature at intake valve closing), and a related cylinder temperature value  224  (e.g., one or more of intake charge temperature, cylinder wall temperature, coolant temperature, and oil temperature). These further basis variables may be selected to further characterize closed cycle efficiency (CCE) under certain engine conditions. 
     The present disclosure recognizes that when the intake valve of a cylinder closes, the combustion event is fixed. As such, the basis variable set for the fuel system is selected to include variables that affect the combustion event after intake valve closing. In general, the basis variable set is a minimum set of variables that is capable of predicting the majority of the combustion event characteristics in the cylinder in at least steady state and transient state operating conditions. The basis variables may also selected based on computational efficiency. For example, in-cylinder oxygen concentration may be selected instead of EGR fraction value, which may be difficult to compute under heavy transient operation. In certain cases, it may be advantageous to include other variables in the basis variable set to account for their effect on combustion in those certain cases, for example, when the engine must warm up from a cold start, including the in-cylinder temperature value  222  would be advantageous. Those having skill in the art, having the benefit of the disclosure herein and having a typical understanding of the particular system in view, would be able to select the appropriate values of a basis variable set. 
     In some cases, the commanded fueling value  214  is interpreted in response to input from an operator of the engine system. For example, the commanded fueling value  214  may correspond to the requested torque from the operator. In various embodiments, the commanded fueling value  214  corresponds to a combustion-relevant fueling value, which is the amount of fuel relevant to the combustion event within the cylinder after intake valve closing. 
     The combustion parameter definer  202  interprets a basis variable set  210  and an optional fuel controller specification set  211 . The fuel controller specification set  211  corresponds to the specifications of one or more controllers in the fuel subsystem, such as fuel controller  112 . The specifications may define an acceptable range of input values for the controller of the fuel system, which can be used to define one or more acceptable ranges for the reference value set  226 . In response to the basis variable set  210  and optionally the fuel controller specification set  211 , the fueling target determiner  204  determines a reference value set  226 . 
     In various embodiments, to perform the functions described herein throughout, the combustion parameter definer  202  may include a rotations per minute (RPM) sensor, an accelerator, an oxygen sensor, a temperature sensor, a pressure sensor, a flow sensor, a humidity sensor, an analog to digital (ADC) converter, a processor, a non-transient computer readable storage medium, computer-readable instruction(s) stored on a non-transient computer readable storage medium, a bus, and/or wired/wireless connection hardware. In other embodiments, one or more of these may also be excluded from the combustion parameter definer  202 . 
     Certain embodiments of the fueling target determiner  204  determine the reference value set  226  in response to a basis variable set  210  including an engine speed  212 , a commanded fueling value  214 , and an in-cylinder oxygen concentration value  216  as a core basis variable set. Various embodiments of the reference value set  226  include a start-of-injection (SOI) command  228  and a rail pressure value. The rail pressure value may be a rail pressure command  230  or a default rail pressure value. The reference value set  226  may also include a main command  236 , which is a fueling value that corresponds to the commanded fueling value  214 . An example main command  236  is the same value as the commanded fueling value  214 . However, the main command  236  may be determined in response to the fuel controller specification set  211 . In some cases, the main command  236  is the combustion-relevant fueling value. In other cases, main command  236  is only a portion of the combustion-relevant fueling value, and the combustion-relevant fueling value also includes one or more of the pilot command(s)  232  and post command(s)  234 . 
     In various embodiments, to perform the functions described herein throughout, the fueling target determiner  204  may include, but is not limited to, a processor, a non-transient computer readable storage medium, computer-readable instruction(s) stored on a non-transient computer readable storage medium, a bus, and/or a wired/wireless connection hardware. In other embodiments, one or more of these may also be excluded from the fueling target determiner  204 . 
     As used herein, a parameter&#39;s trajectory is defined as a value or a set of values representing the parameter over a selected time horizon or time trajectory. A parameter&#39;s trajectory as a value, for example, represents the accumulation over time of the parameter, and may be interpreted in response to consolidating a set of parameter values by a process, such as integration, averaging, or other known processes. 
     Further embodiments of the reference value set  226  include a rail pressure command  230 , a pilot command(s)  232 , a post command(s)  234 , a fuel injection time trajectory  238  (e.g., a fuel injection amount versus time trajectory command value), and a fuel rail pressure trajectory  240  (e.g., a fuel injection pressure versus time trajectory command value). With respect to the pilot command(s) and post command(s)  232 ,  234 , some embodiments are combustion relevant, while in other embodiments, they are not combustion relevant and may form part of an additional fueling amount. An example of a post command  234  that is an additional fueling amount is a very late post command intended to deliver fuel to an exhaust aftertreatment system instead of contributing to torque development. An example time trajectory for these parameters is on the order of milliseconds. 
     In some embodiments, the fueling target determiner  204  stores relationships between the basis variable set  210  and the reference value set  226  as a series of reference surfaces, each reference surface corresponding to a reference value and having one or more basis variables as inputs. The relationships are determined during calibration. An example calibration may determine the reference surfaces in response to key basis variable measurements at various operating points of the engine system. In some cases, a target may be used to calibrate the reference surfaces, such as a closed cycle efficiency (CCE) target. The target value may be a predefined target, an improved value, a minimum value, a maximum value, or an optimum value. The reference surfaces are optionally calibrated to meet the target(s) and also to meet other objectives or constraints (e.g., constraint value  225 ). An example reference surface is generated that provides reference value sets as outputs, or targets, to achieve CCE targets within physical and/or emissions constraints (described in detail herein elsewhere), in response to basis variable sets and optionally a particular CCE target as inputs. 
     With respect to the reference value set, the present disclosure recognizes that a processing subsystem  200  is often paired with a fuel system, such as fuel system  110 , which accepts a particular type of inputs and range of inputs. Those having skill in the art, having the benefit of the disclosure herein and having a typical understanding of the particular system in view, would be able to select the appropriate values for the reference value set  226 . 
     Various embodiments of the fuel control commander  206  determine a fueling command set  252  in response to the reference value set  226 . The reference value set  226  provides targets for the fuel control commander  206 . In some cases, the fueling command set  252  provides the same values as the reference value set  226 . In other cases, the fuel control commander  206  modifies the reference value set  430  before providing the fueling command set  252 . The example fuel control commander  206  optionally modifies the reference value set  226  in response to one or more constraint values  225 , including but not limited to one or more of a physical limit (e.g., maximum torque, maximum rail pressure, etc), a fuel system response time, an actuator saturation, a present fault value, and/or other known constraints. 
     In various embodiments, to perform the functions described herein throughout, the fuel control commander  206  may include, but is not limited to, a fuel injector, a fuel rail pressure pump, a processor, a non-transient computer readable storage medium, computer-readable instruction(s) stored on a non-transient computer readable storage medium, a bus, and/or wired/wireless connection hardware. In other embodiments, one or more of these may also be excluded from the fuel control commander  206 . 
     In additional or alternative embodiments, the fuel control commander  206  comprises a fuel control circuit. To perform the functions described herein throughout, an example fuel control circuit may include, but is not limited to, an analog circuit, a digital circuit, an analog-to-digital converter (ADC) or vice versa, a processor, a non-transient computer readable storage medium, computer-readable instruction(s) stored on a non-transient computer readable storage medium, a bus, and/or wired/wireless connection hardware. In other embodiments, one or more of these may also be excluded from the fuel control circuit. 
     The present disclosure recognizes that a particular fuel system may include a physical fuel controller calibrated to control at least one physical component of the fuel system and that various fuel systems respond uniquely to commands due to design differences and manufacturing tolerances. Thus, an example fuel control commander  206  optionally adjusts to the reference value set  226  in response to limitations or constraints of the fuel system  110 . Those having skill in the art, having the benefit of the disclosure herein and having a typical understanding of the particular system in view, would be able to select the appropriate fueling command set  252  for a fuel system  110 . 
     One of skill in the art, having the benefit of the disclosures herein, will recognize that the processing subsystem  200  and the controller  125  perform operations that improve various technologies and provide improvements in various technological fields. Without limitation, example and non-limiting technology improvements include improvements in combustion performance of internal combustion engines, improvements in emissions performance, aftertreatment system regeneration, engine torque generation and torque control, engine fuel economy performance, improved durability of exhaust system components for internal combustion engines, and engine noise and vibration control. Without limitation, example and non-limiting technological fields that are improved include the technological fields of internal combustion engines, fuel systems therefore, aftertreatment systems therefore, air handling devices therefore, and intake and exhaust devices therefore. 
     The schematic flow diagram and related description which follows provides an illustrative embodiment of performing procedures for controlling the condition of an exhaust gas stream. Operations illustrated are understood to be exemplary only, and operations may be combined or divided, and added or removed, as well as re-ordered in whole or part, unless stated explicitly to the contrary herein. Certain operations illustrated may be implemented by a computer executing a computer program product on a non-transient computer readable storage medium, where the computer program product comprises instructions causing the computer to execute one or more of the operations, or to issue commands to other devices to execute one or more of the operations. 
       FIG. 3  is a schematic flow chart diagram of an example procedure  300  for controlling the fuel system  110  of the engine system  100 , according to some embodiments. The procedure includes an operation  305  to interpret a fueling basis variable set. The fueling basis variable set is selected to characterize the majority of effects of the fuel subsystem. In operation  310 , a fuel controller specification set is interpreted. An example fuel controller specification set defines the acceptable types of inputs and their range for a controller of the fuel subsystem. 
     In operation  315 , a fueling reference value set is determined in response to the fueling basis variable set and the fuel controller specification set. The fueling reference value set is a set of target values for performance of the fuel subsystem. By including the fuel controller specification set, the target values may be determined within acceptable ranges of the specification of one or more controllers of the fuel subsystem to facilitate more accurate control of the fuel subsystem. In some embodiments, the fuel controller specification set is included in the calibration of the fueling reference value set in response to the fueling basis variable set. 
     In operation  320 , a fueling command set is determined in response to the fueling reference value set. The fueling command set may be the same as fueling reference value set. Alternatively or in combination, the fueling reference value set may be modified to provide a fueling command set. For example, the fueling command set is optionally determined further in response to constraints (or limitations) of the fuel subsystem. In some embodiments, one or more constraints (e.g., physical, emissions, or otherwise) of the fuel subsystem are included in calibration of the fueling reference value set in response to the fueling basis variable set. In such embodiments, the fueling reference value set is optionally not modified in response to those constraints at run-time. 
     Finally, in operation  325  an internal combustion engine is fueled in response to the fueling command set. The fueling step may include providing the fueling command set to a controller of the fuel subsystem. The controller of the fuel system may operate components of the fuel system, such as one or more injectors or fuel rails, to provide fuel to the internal combustion engine. 
     Other components of the system  100  may be controlled in a similar manner, using basis variables, reference values, and commands. 
       FIG. 4  is a schematic illustration of a processing subsystem  400  of the engine system  100  including a controller  125  to perform certain operations to control the air handling system  115 , according to some embodiments. As shown, the controller  125  includes an air handling parameter definer  402 , an air handling target determiner  404 , and an air handling control commander  406  (e.g., air handling control circuit). The air handling parameter definer  402  interprets one or more basis variables for air handling. An example basis variable set characterizes open cycle efficiency (OCE), which considers the work of the air handling system to provide air, which may be compressed, or recirculated exhaust to the cylinder. The air handling target determiner  404  determines an air handling reference value set in response to a key basis variable set for air handling. An example air handling reference value set corresponds to target values for the air handling system. Some target values are conformed to the specification set of one or more physical controllers of the air handling system, such as air handling controller  117 . The air handling control commander  406  provides one or more air handling command values in response to a reference value set for air handling. An example command value set modifies the reference value set due to being calibrated to match the air handling system or due to other limits. Further, the air handling system may deliver air to the internal combustion engine in response to the reference value set upon receiving the one or more air handling command values. 
     Similar to the combustion parameter definer  202 , the air handling parameter definer  402  interprets parameters to characterize the air handling system and provides these parameters to the controller  125 . Parameters of interest may include but are not limited to charge flow, exhaust oxygen, humidity (e.g., water vapor displacement), intake oxygen, exhaust manifold temperature/pressure, and intake manifold temperature/pressure. An example air handling parameter definer  402  interprets a predicted engine speed trajectory  412  and a predicted fueling trajectory  414 . An example response time for these parameters is on the order of seconds. A trajectory may be an expected or actual value over a few time steps or a few seconds. Time steps reference execution time steps, such as controller execution time steps, for example, 5 ms, 20 ms, or other values known to one having skill in the art having the benefit of the disclosure herein. Example engine speed trajectories  412  may extend from 100 ms to 10 s, or in some cases beyond 10 s depending on the transient operations at the time and the parameters to be optimized. Example fueling trajectories  414  may extend from 10 ms to 1 s, or in some cases up to 5 s or beyond depending on the transient operations at the time and the parameters to be optimized. 
     The example air handling parameter definer  402  is in operative communication with one or more sensors. The air handling parameters are handling parameter definer  402  are interpreted in response to signals, data, or information received from the one or more sensors. A non-limiting list of example sensors include an intake manifold pressure sensor, an intake manifold temperature sensor, an EGR flow sensor (e.g., orifice with delta-P sensor), an absolute pressure sensor, a temperature sensor, a wideband exhaust gas oxygen sensor, a humidity sensor, an intake oxygen sensor, and an exhaust gas temperature sensor. A person having skill in the art and the benefit of the disclosure herein would be able to select the one or more sensors for characterizing a parameter of interest for the air handling system. In some embodiments, the one or more sensors are part of the air handling parameter definer  402 . 
     The example controller  125  shown includes a basis variable set  410 . The basis variable set may include one or more of a predicted engine speed trajectory  412 , a predicted fueling trajectory  414 , an aftertreatment state value  416 , and an ambient value  418 . Aftertreatment state values  416  include, without limitation, the temperature of any aftertreatment component, the flow rate through any aftertreatment component, the predicted efficiency of any aftertreatment component, and/or the pressure drop of any aftertreatment component. Ambient values  418  include, without limitation, the ambient temperature, the ambient pressure, the ambient humidity, and/or the ambient heat transfer around any aftertreatment component. 
     An example basis variable set  410  includes the predicted engine speed trajectory  412 , the predicted fueling trajectory  414 , and the ambient value  418 . The example basis variable set  410  is selected to characterize open cycle efficiency (OCE) within the engine system. As utilized herein, OCE represents the efficiency of the engine system to bring air into a cylinder before intake valve closing. Example aftertreatment state values, which may also affect OCE, include one or more of a space-velocity value  420 , a catalyst related temperature  422  (e.g., measured directly or indirectly), an ammonia (NH 3 ) storage value  424  (e.g., ammonia storage in an SCR catalyst), a diesel particulate filter (DPF) loading value  426 , and a NO X  conversion efficiency value  428  (e.g., SCR catalyst conversion efficiency or DeNO X ). 
     The present disclosure recognizes that the overall efficiency of the engine system is affected by the efficiency of the air handling system in bringing air into a cylinder before intake valve closing. The key basis variables for air handling is the minimum set of variables that is capable of predicting the majority of the air handling characteristics in at least steady state and transient state operation conditions. The key basis variables for air handling may further be selected based on computational efficiency. Those having skill in the art, having the benefit of the disclosure herein and having a typical understanding of the particular system in view, would be able to select the appropriate values of a basis variable set. 
     In various embodiments, to perform the functions described herein throughout, the air handling parameter definer  402  may include, but is not limited to, a rotations per minute (RPM) sensor, a fuel injector, an accelerator, a temperature sensor, a pressure sensor (e.g., absolute or differential), a humidity sensor, a NO X  sensor, an ammonia sensor, a flow sensor, an analog to digital (ADC) converter, a processor, a non-transient computer readable storage medium, computer-readable instruction(s) stored on a non-transient computer readable storage medium, a bus, and/or wired/wireless connection hardware. In other embodiments, one or more of these may be excluded from the air handling parameter definer  402 . 
     The air handling target determiner  404  interprets the basis variable set  410  and an optional air handling controller specification set  411 . The air handling controller specification set  411  corresponds to the specifications of one or more controllers in the air handling system  115 , such as air handling controller  117 . The specifications may define an acceptable range of input values for the controller of the air handling system, which can be used to define one or more acceptable ranges for the reference value set  430 . In response to the basis variable set  410  and optionally the air handling controller specification set  411 , the air handling target determiner  404  determines the reference value set  430 . Further embodiments of the air handling target determiner  404  determine the reference value set  430  further in response a threshold criteria set  442 , which may include objectives or constraints for the reference value set. In some embodiments, the threshold criteria set  442  is included during calibration to establish relationships between the reference value set  430  and the basis variable set  410 . 
     In various embodiments, the air handling target determiner  404  may include a processor, a non-transient computer readable storage medium, computer-readable instruction(s) stored on a non-transient computer readable storage medium, a bus, and/or wired/wireless connection hardware. In other embodiments, one or more of these may be excluded from the air handling target determiner  404 . 
     Various embodiments of the reference value set  430  include a mass charge flow (MCF) value  432 . Further embodiments include an exhaust gas recirculation (EGR) fraction value  434 . Alternatively or in addition, some embodiments include pumping work target(s)  436 . The MCF value  432 , EGR fraction value  434 , and pumping work target(s)  436  may be considered part of an air handling reference subset  431  of the reference value set  430 . In yet further embodiments, the reference value set  430  includes at least one of a start-of-injection (SOI) command  438  and a rail pressure command  440  as a fueling reference subset  433  of the reference value set  430 . Referring to  FIG. 2 , a fueling command may include a pilot command(s)  232  and/or a post command(s)  234  in addition to a main command  236 . 
     The present disclosure recognizes that a processing subsystem  400  is often paired with an air handling system, such as air handling system  115 , which accepts a particular type of input and range of inputs. The processing subsystem  400  may further be in operative communication with a fuel system  110 , in order to coordinate and optimize, for example, brake thermal efficiency (BTE) of the engine system  100 . Those having skill in the art, having the benefit of the disclosure herein and having a typical understanding of the particular system in view, would be able to select the appropriate values for the reference value set  430 , the air handling reference subset  431 , and the fueling reference subset  433 . 
     In some embodiments, the air handling target determiner  404  stores relationships between the basis variable set  410  and the reference value set  430  as a series of reference surfaces, each reference surface corresponding to a reference value and having one or more basis variables as inputs. The relationships may be determined during calibration. An example calibration determines the reference surfaces in response to key basis variable measurements at various operating points of the engine system. In some cases, a target may be used to calibrate the reference surfaces, such as an open cycle efficiency (OCE) target. The target value may be a predefined target, an improved value, a minimum value, a maximum value, or an optimum value. The reference surfaces are optionally calibrated to meet the target(s) and also to meet other objectives or constraints (e.g., selected from the threshold criteria set  442 ). An example reference surface is generated that provides reference value sets as outputs, or targets, to achieve OCE targets within physical and/or emissions constraints, in response to basis variable sets and optionally a particular OCE target as inputs. 
     Certain embodiments of the air handling control commander  406  determine an air handling command set  408  in response to the reference value set  430 . The reference value set  430  provides targets for the air handling control commander  406 . In some cases, the air handling control commander  406  provides the reference value set  430  as the air handling command set  408 . In other cases, the air handling control commander  406  modifies the reference value set  430  before providing the air handling command set  408 . In further cases, the air handling control commander  406  modifies the reference value set  430  in response to a constraint (described herein elsewhere in more detail). 
     In various embodiments, to perform the functions described herein throughout, the air handling control commander  406  may include, but is not limited to, an EGR valve, a VGT, an engine fan, a fuel injector, a fuel rail pressure pump, a processor, a non-transient computer readable storage medium, computer-readable instruction(s) stored on a non-transient computer readable storage medium, a bus, and/or wired/wireless connection hardware. In other embodiments, one or more of these may be excluded from the air handling control commander  406 . 
     In additional or alternative embodiments, the air handling control commander  406  comprises an air handling control circuit. To perform the functions described herein throughout, an example air handling control circuit may include, but is not limited to, an analog circuit, a digital circuit, an analog-to-digital converter (ADC) or vice versa, a processor, a non-transient computer readable storage medium, computer-readable instruction(s) stored on a non-transient computer readable storage medium, a bus, and/or wired/wireless connection hardware. In other embodiments, one or more of these may also be excluded from the air handling control circuit. 
     The present disclosure recognizes that a particular air handling system may include one or more physical air handling controllers calibrated to control at least one physical component of the air handling system and that various air handling systems respond uniquely to commands due to design differences and manufacturing tolerances. Thus, an example air handling control commander  406  provides adjustments to the reference value set  430  in response to limitations or constraints of the air handling system  115 . Those having skill in the art, having the benefit of the disclosure herein and having a typical understanding of the particular system in view, would be able to select the appropriate air handling command set  408  for an air handling system  115 . In this manner, the air handling system  115  may be controlled utilizing a key basis variable set  410 , a reference value set  430 , and a command set  408 . 
       FIG. 5  is a schematic illustration of the air handling target determiner  404  of processing subsystem  400 , according to some embodiments. An example air handling target determiner  404  includes a predictive model  446  and an optimization routine  448 , which are optionally utilized to provide the reference value set  430  in response to the basis variable set  410  and the air handling controller specification set  411 . 
     An example air handling target determiner  404  determines a design reference value set  444  in response to the basis variable set  410  and optionally the air handling controller specification set  411 . The design reference value set  444  may be determined similarly to, may include similar values to, and may be selected similarly as described with respect to the reference value set  430 . Thus, the design reference value set  444  includes at least one of an MCF value  432 , an EGR fraction value  434 , pumping work target(s)  436 , an SOI command  438 , and a rail pressure command  440 . These one or more design reference values serve as initial target values that may be modified in iteratively in a cycle until certain conditions are met prompting the reference value set  430  to be provided. In various embodiments, initial design reference value set  444  is a steady state reference value set. In some cases, the steady state reference value set is provided as an initial guess or estimate for the design reference value set  444 . In other cases, the design reference value set  444  as the steady state reference value set is provided as the reference value set  430  in response to a steady state operating condition (e.g., the air handling target determiner  404  acts as a unity gain filter). 
     With initial target values available, an output set  447  of the predictive model  446  is determined as a step in an iteration. An example output set  447  includes at least one of a predicted open cycle efficiency (OCE) trajectory, a predicted closed cycle efficiency (CCE) trajectory, a predicted NO X  value, a predicted smoke value, a predicted torque value, a predicted mass charge flow (MCF) value, and a predicted exhaust gas recirculation (EGR) fraction value, a predicted cylinder pressure value, a predicted turbocharger surge, a predicted turbocharger speed, and a predicted physical value. The output set  447  may be determined in response to the design reference value set  444  and one or more basis variables of the basis variable set  410 . In certain embodiments, the predictive model is a control-oriented model (COM) of the air handling subsystem that is run over a time trajectory. The reference value set  430  may be further determined in response to the output set  447 . 
     In response to the output set  447 , an example embodiment of the air handling target determiner  404  further checks for traversal of a feasible trajectory of the air handling system  115 . Alternatively or in addition, in response to the output set  447 , an example embodiment of the air handling target determiner  404  also checks for a hardware limit violation. Examples of hardware limit violations are turbocharger surge  470  or excessive turbocharger speed  472 . The reference value set  430  may be determined in response to either or both of these checks. 
     Various embodiments of an optimization routine  448  determine when to provide the reference value set  430 . An example optimization routine  448  operates to provide the reference value set in response to an output condition to end a cycle of iterations, such as achieving a target BTE trajectory  480 , reaching a predetermined time limit, or meeting some other condition. 
     Until the output condition is met, the air handling target determiner  404  may constrain the design reference value set  444  in response to at least one of the target BTE trajectory  480  and the threshold criteria set  442 . For example, the cycle of iterations continues with a next iteration. An example optimization routine  448  continues to determine a next design variable set  444  with which to begin a next iteration in response to the predictive model output set  447  and optionally the threshold criteria set  442 . 
     An example target BTE trajectory  480  is an optimum or maximum BTE trajectory over a chosen time horizon. Some embodiments of the target BTE trajectory  480  are calculated as the product of a target OCE trajectory  454  and a target CCE trajectory  456 . Often, optimizing the target BTE trajectory  480  requires balancing CCE and OCE to achieve a local or global optimum. For example, a greater CCE may be achieved with greater amounts of compressed air in the cylinder, which requires more work from the air handling system and a lesser OCE. Though a global optimum could produce the highest efficiency, a local optimum can be preferred over a global optimum, for example, when time constraints do not allow for the processing time required to find the global optimum. Non-limiting examples of local optimums include local minimums or maximums of a predictive operation (e.g. by derivative), local minimums or maximums of an error-calculating operation, and a result from a tree search (e.g. Monte Carlo). The optimization routine  448  may determine the reference value set  430  or the design reference value set  444  further in response to the target BTE trajectory  480 . 
     In various embodiments, the optimization routine  448  constrains the reference value set  430  or the design reference value set  444  further in response to the threshold criteria set  450 , for example, so that the engine system  100  operates to achieve one or more objective values  450  optionally within the limits of one or more constraint values  452 . In some embodiments, the values selected for the output set  447  correspond to the values selected for the threshold criteria set  442 . The output set  447  may be compared to the threshold criteria set  442 . The reference value set  430  may be further constrained in response to the comparison. 
     Various embodiments of the threshold criteria set  442  include at least one of an objective value subset  450  and a constraint value subset  452 . The objective value subset  450  provides objectives or targets for performance, whereas the constraint value set  452  provides constraints that are physical (e.g., hardware based), regulatory (e.g., related to emission limit), feasible in the state space, or otherwise selected. An example objective value subset  450  includes at least one of a target open cycle efficiency (OCE) trajectory  454 , a target closed cycle efficiency (CCE) trajectory  456 , a target NO X  value  458 , a target smoke value  460 , a target torque value  462 , a target mass charge flow (MCF) value  464 , and a target exhaust gas recirculation (EGR) fraction value  466 . An example constraint value subset  452  includes one or more a peak cylinder pressure value  468 , a turbocharger surge  470 , an excessive turbocharger speed  472 , a physical limit value  474 , a mass charge flow (MCF) limit value  476 , an exhaust gas recirculation (EGR) limit value  478 , and a regulatory limit value  479  (e.g., related to an emission limit). 
     To summarize, an initial design reference value set is determined in response to the basis variable set and optionally the air handling controller specification set. The initial design reference value set may be a best guess, such as a steady state reference value set. This set is provided to a predictive model, which provides an output set. An optimization routine optionally constrains the set in response to a threshold criteria set and the output set of the predictive model. The set may be provided as a design reference value set for another iteration in the cycle or may be provided as a reference value set when an output condition is met. In this way, the air handling target determiner  404  is capable of generating an iteratively optimized and/or improved reference value set  430 . 
       FIG. 6  is a schematic illustration of an example predictive model  446  of the processing subsystem  400 , according to some embodiments. The predictive model  446  includes one or more submodels to provide the output set  447  in response to the design reference value set  444 . An example predictive model  446  includes a closed-loop air handling model  482 , an in-cylinder oxygen estimation model  484 , and an in-cylinder combustion model  486 . The models may work cooperatively to provide the output set  447 . In some cases, the output set  447  is updated in response to the submodels  482 ,  484 ,  486 . For example, the last in-cylinder combustion information may be used to estimate the amount of air being recirculated for the next combustion. The amount of air being provided at intake and being recirculated may be used to estimate in-cylinder oxygen. The in-cylinder oxygen estimation may be used to estimate the next in-cylinder combustion characteristics. In this way, the predictive model  446  provides an output set  447  that may be compared to the threshold criteria set  442 . 
     An example closed-loop air handling model  482  determines an intake manifold pressure value  488  and an intake manifold temperature value  490 . An example in-cylinder combustion model  486  determines an exhaust manifold pressure value  492  and an exhaust manifold temperature value  494 . The in-cylinder oxygen estimation model  484  determines the amount or concentration of oxygen provided into the cylinder. 
       FIG. 7  is a schematic flow chart diagram of an example procedure  500  for controlling the air handling system  115  of the engine system  100 , according to some embodiments. The procedure includes an operation  505  to interpret an air handling variable set. The air handling basis variable set is selected to characterize the majority of effects of the air handling subsystem. In operation  510 , an air handling specification set is interpreted. An example air handling specification set defines the acceptable types of inputs and their range for a controller of the air handling subsystem. 
     In operation  515 , an air handling reference value set is determined in response to the air handling basis variable set and the air handling controller specification set. The air handling reference value set is a set of target values for performance of the air handling subsystem. By including the air handling controller specification set, the target values may be determined within acceptable ranges of the specification of one or more controllers of the air handling subsystem to facilitate more accurate control of the air handling subsystem. Operation  515  may include updating one or more predictive models and/or constraining an air handling reference value set to meet various threshold criteria. In some embodiments, the air handling controller specification set is included in the calibration of the air handling reference value set in response to the air handling basis variable set. 
     In operation  520 , an air handling command set is determined in response to the air handling reference value set. The air handling command set may be the same as air handling reference value set. Alternatively or in combination, the air handling reference value set may be modified to provide an air handling command set. For example, the air handling command set may be determined to take into account constraints (or limitations) of the air handling subsystem. In some embodiments, one or more constraints (e.g., physical, emissions, or otherwise) of the air handling subsystem are included in calibration of the air handling reference value set in response to the air handling basis variable set. In such embodiments, the fueling reference value set is optionally not modified in response to those constraints at run-time. 
     Finally, in operation  525 , air is delivered to an internal combustion engine in response to the air handling command step. The delivering step may include providing the air handling command set to a controller of the air handling subsystem. The controller of the air handling system may operate components of the air handling system, such as one or more turbochargers and EGR valves, to deliver air to the internal combustion engine. 
       FIG. 8  is a schematic illustration of a processing subsystem  600  of the engine system  100  including a controller  125  to perform certain operations to control the aftertreatment system  120 , according to some embodiments. As shown, the controller  125  includes an aftertreatment parameter definer  602 , an aftertreatment target determiner  604 , and an aftertreatment control commander  606  (e.g., aftertreatment control circuit). The aftertreatment parameter definer  602  interprets one or more basis variables for aftertreatment. An example basis variable set characterizes a moving average of emission in a receding time horizon. The aftertreatment target determiner  604  determines an aftertreatment reference value set in response to a key basis variable set for aftertreatment. An example aftertreatment reference value set corresponds to target values for the aftertreatment system. Some target values are conformed to the specification set of one or more physical controllers of the aftertreatment system, such as aftertreatment controller  124 . The aftertreatment control commander  606  provides one or more aftertreatment command values in response to a reference value set for aftertreatment. An example command value set modifies the reference value set due to being calibrated to match the aftertreatment system or due to other limits. Further, the aftertreatment system  120  may treat the exhaust from the internal combustion engine in response to the reference value set upon receiving the one or more aftertreatment command values. 
     The aftertreatment parameter definer  602  interprets parameters and provides them to the controller  125 . An example aftertreatment parameter definer  602  interprets one or more of a space-velocity value  420 , an exhaust related temperature  614  (e.g., an exhaust temperature, a catalyst temperature, DPF temperature, EGR temperature, etc), an ambient value  616 , an ammonia storage value  424 , and an NO X  conversion efficiency value  428 . 
     The example controller  125  shown includes a basis variable set  610 . The basis variable set includes one or more parameters interpreted by the aftertreatment parameter definer  602 , such as the space-velocity value  420 , the exhaust related temperature  614 , the ambient value  616 , the ammonia storage value  424 , and the NO X  conversion efficiency value  428 . An example basis variable set includes the space-velocity value  612 , the exhaust related temperature  614 , and the ambient value  616 . The example basis variable set  610  is selected to characterize an emissions trajectory within the engine system, such as a system out NO X  trajectory (e.g., NO X  at the tailpipe over time). An example time trajectory is on the order of hours. 
     The present disclosure recognizes that the moving average of emissions in a receding time horizon may be used to regulate the cumulative emissions of engine system  100 . A cumulative emissions threshold may be selected in response to, for example, a regulatory value, an offset of the regulatory value (e.g., below the regulatory value or above the regulatory value) for emission credit use or provision, an emission credit trading value, or a sociability requirement. An emission credit trading value may be determined in response to, for example, run-time credits (e.g., in response to real-time emission credit trading) or design-time credits (e.g., in response to a predetermined allocation of emission credits for a particular engine). Typical cumulative emissions include, without limitation, accumulated NO X  and/or particulate matter. Example particulate matter includes unburned hydrocarbons and/or soot. The key basis variables for aftertreatment is the minimum set of variables that is capable of predicting the majority of the aftertreatment characteristics in at least steady state and transient state operation conditions. The key basis variables for aftertreatment may further be selected based on computational efficiency. Those having skill in the art, having the benefit of the disclosure herein and having a typical understanding of the particular system in view, would be able to select the appropriate values of a basis variable set. 
     In various embodiments, to perform the functions described herein throughout, the aftertreatment parameter definer  602  may include, but is not limited to, a pressure sensor (e.g., absolute or differential), a temperature sensor, a NO X  sensor, an ammonia sensor, an analog to digital (ADC) converter, a processor, a non-transient computer readable storage medium, computer-readable instruction(s) stored on a non-transient computer readable storage medium, a bus, and/or wired/wireless connection hardware. In other embodiments, one or more of these may be excluded from the aftertreatment parameter definer  602 . 
     The aftertreatment target determiner  604  interprets the basis variable set  610  and optionally the aftertreatment controller specification set  611 . The aftertreatment controller specification set  611  corresponds to the specifications of one or more controllers in the aftertreatment system  120 , such as aftertreatment controller  124 . The specifications may define an acceptable range of input values for the controller of the aftertreatment system, which can be used to define one or more acceptable ranges for the reference value set  620 . In response to the basis variable set  610  and optionally the aftertreatment controller specification set  611 , the aftertreatment target determiner  604  determines the reference value set  430 . Further embodiments of the aftertreatment target determiner  604  determine the reference value set  620  further in response a threshold criteria set  626 , which may include objectives or constraints (e.g., physical, emissions, or otherwise) for the reference value set. In some embodiments, the threshold criteria set  626  is included during calibration to establish relationships between the reference value set  620  and the basis variable set  610 . 
     Various embodiments of the reference value set  620  include at least one of a target NO X  conversion efficiency value  622  (e.g., target NO X  conversion efficiency of the SCR catalyst) and a target system out NO X  value  624  (e.g., target NO X  at the tailpipe). One of skill in the art would understand that the target NO X  conversion efficiency value  622  is an emergent value, and contemplating a particular system and having the benefit of the disclosures herein would understand the values of exhaust temperature, catalyst temperature, exhaust flow rate, catalyst loading, ammonia to NO X  ratio, and/or other similar parameters to achieve a particular target NO X  conversion efficiency value  622 . The present disclosure recognizes that a processing subsystem  600  is often paired with an aftertreatment system, such as aftertreatment system  120 , which accepts a particular type of input and range of inputs. Further, the present disclosure recognizes that the target NO X  conversion efficiency value  622  and the target system out NO X  value  624  are capable of defining the parameters to control a majority of effects in the aftertreatment system  120 . Those having skill in the art, having the benefit of the disclosure herein and having a typical understanding of the particular system in view, would be able to select the appropriate values for the reference value set  620 . 
     In some embodiments, the aftertreatment target determiner  604  stores relationships between the basis variable set  610  and the reference value set  620  as a series of reference surfaces, each reference surface corresponding to a reference value and having one or more basis variables as inputs. The relationships may be determined during calibration. An example calibration determines the reference surfaces in response to key basis variable measurements at various operating points of the engine system. In some cases, a target is optionally used to calibrate the reference surfaces, such as an engine brake specific fuel consumption (EBSFC) trajectory, a number of DPF regenerations, and/or an aggregate emissions trajectory. The target value may be a predefined target, an improved value, a minimum value, a maximum value, or an optimum value. In some embodiments, the target includes a minimum EBSFC trajectory. In additional or alternative embodiments, the target includes a minimum number of DPF regenerations over a time trajectory. An example reference surface is generated that provides reference value sets as outputs, or targets, to achieve EBSFC targets within physical and/or emissions constraints, in response to basis variable sets and optionally a particular OCE target as inputs. 
     In various embodiments, to perform the functions described herein throughout, the aftertreatment target determiner  604  may include, but is not limited to, a processor, a non-transient computer readable storage medium, computer-readable instruction(s) stored on a non-transient computer readable storage medium, a bus, and/or wired/wireless connection hardware. In other embodiments, one or more of these may be excluded from the aftertreatment target determiner  604 . 
     Certain embodiments of the aftertreatment control commander  606  determine an aftertreatment command set  608  in response to the reference value set  620 . The reference value set  620  provides targets for the aftertreatment control commander  606 . In some cases, the aftertreatment control commander  606  provides the reference value set  620  as the aftertreatment command set  608 . In other cases, the aftertreatment control commander  606  modifies the reference value set  620  before providing the aftertreatment command set  608 . In further cases, the aftertreatment control commander  606  modifies the reference value set  620  in response to a constraint, such as a physical limit or regulatory limit (e.g., selected from threshold criteria set  626 ). 
     In various embodiments, to perform the functions described herein throughout, the aftertreatment control commander  606  may include, but is not limited to, a diesel exhaust fluid (DEF) valve, an ammonia fluid valve, a fuel injector, an EGR valve, a VGT, a processor, a non-transient computer readable storage medium, computer-readable instruction(s) stored on a non-transient computer readable storage medium, a bus, and/or wired/wireless connection hardware. In other embodiments, one or more of these may be excluded from the aftertreatment control commander  606 . 
     In additional or alternative embodiments, the aftertreatment control commander  606  comprises an aftertreatment control circuit. To perform the functions described herein throughout, an example aftertreatment control circuit may include, but is not limited to, an analog circuit, a digital circuit, an analog-to-digital converter (ADC) or vice versa, a processor, a non-transient computer readable storage medium, computer-readable instruction(s) stored on a non-transient computer readable storage medium, a bus, and/or wired/wireless connection hardware. In other embodiments, one or more of these may also be excluded from the aftertreatment control circuit. 
     The present disclosure recognizes that a particular aftertreatment system may include one or more physical aftertreatment controllers calibrated to control the particular physical components of the aftertreatment system and that various aftertreatment systems respond uniquely to commands due to design differences and manufacturing tolerances. Thus, an example aftertreatment control commander  606  provides adjustments to the reference value set  620  in response to limitations or constraints of the aftertreatment system  120 . Those having skill in the art, having the benefit of the disclosure herein and having a typical understanding of the particular system in view, would be able to select the appropriate aftertreatment command set  608  for an aftertreatment system  120 . In this manner, the aftertreatment system  120  may be controlled utilizing a key basis variable set  610 , a reference value set  620 , and/or a command set  608 . 
       FIG. 9  is a schematic illustration of the aftertreatment target determiner  604  of processing subsystem  600 , according to some embodiments. An example aftertreatment target determiner  604  includes a predictive model  632  and an optimization routine  634 , which are optionally utilized to provide the reference value set  620  in response to the basis variable set  610  and the aftertreatment controller specification set  611 . 
     An example aftertreatment target determiner  604  determines a design reference value set  630  in response to the basis variable set  610  and optionally the aftertreatment controller specification set  611 . The design reference value set  630  may be determined similarly to, may include similar values to, and may be selected similarly as described with respect to the reference value set  620 . Thus, the design reference value set  630  includes at least one of target NO X  conversion efficiency value  622  and a target system out NO X  value  624 . These one or more design reference values serve as initial target values that may be modified in iteratively in a cycle until certain conditions are met, at which time the design reference value set  630  is provided as the reference value set  620 . In various embodiments, initial design reference value set  630  is a steady state reference value set. In some cases, the steady state reference value set is provided as an initial guess or estimate for the design reference value set  630 . In other cases, the design reference value set  630  as the steady state reference value set is provided as the reference value set  620  in response to a steady state operating condition (e.g., the aftertreatment target determiner  604  acts as a unity gain filter). 
     With initial target values available, an example output set  633  of the predictive model  632  is determined as a step in an iteration. The example output set  633  includes at least one of a predicted NO X  conversion efficiency value  650 , a predicted system out NO X  value  649 , and a predicted ammonia slip value  651 . The values of the example output set  633  optionally represent trajectories of such values over time. The output set  633  may be determined in response to the design reference value set  630  and one or more basis variables of the basis variable set  610 . In certain embodiments, the predictive model includes one or more submodels, such as a closed-loop model of the SCR system  636 , a tailpipe metrics model  638 , and an aftertreatment state value model  640 . An example output set  633  is determined and/or updated in response to one or more of these submodels. In particular, the output set  633  is optionally determined and/or updated in response to one or more submodel outputs, such as a predicted space-velocity value  642 , a predicted catalyst related temperature  644 , a predicted ammonia storage value  646 , a predicted DPF loading value  648 , and a predicted NO X  conversion efficiency value  650 . The example reference value set  620  is optionally determined further in response to the output set  633 . Further, the example reference value set  620  is optionally determined in response to the comparison of one or more predicted values in the output set  633  to a corresponding threshold value in the threshold criteria set  626 . 
     Various embodiments of an optimization routine  634  determine when to provide the reference value set  620 . An example optimization routine  634  operates to provide the reference value set in response to an output condition to end a cycle of iterations. An example output condition is meeting one or more consumption targets  658 , meeting a target aggregate emissions trajectory  664 , meeting a predetermined time limit, and/or meeting some other condition. The one or more consumption targets  658  may include a target (EBSFC) trajectory  660  and/or a target number of diesel particulate filter (DPF) regenerations  662 . For example, the consumption target may include an improved or minimum fuel or NO X  reductant fluid consumption level. 
     Until the output condition is met, the aftertreatment target determiner  604  may constrain the design reference value set  630  in response to at least one of the consumption targets  658  and/or the target aggregate emissions trajectory  664 . For example, the cycle of iterations continues with a next iteration. An example optimization routine  634  continues to determine a next design variable set  630  with which to begin a next iteration in response to the predictive model output set  633  and optionally the threshold criteria set  626 . Though a global optimum could produce the highest efficiency, a local optimum can be preferred over a global optimum, for example, when time constraints do not allow for the processing time required to find the global optimum. The optimization routine  634  may determine the reference value set  620  or the design reference value set  630  further in response to the constrained design reference value set  630 . 
     In various embodiments, the optimization routine  634  constrains the reference value set  620  or the design reference value set  630  further in response to the threshold criteria set  626 . In some embodiments, the values selected for the output set  633  correspond to the values selected for the threshold criteria set  626 . The output set  633  may be compared to the threshold criteria set  626 . Various embodiments of the threshold criteria set  626  include at least one of a target NO X  conversion efficiency trajectory  652 , a target system out NO X  trajectory  654 , and a target ammonia slip trajectory  656 . The design reference value set  630  may be further constrained in response to the comparison. 
     To summarize, an initial design reference value set  630  is determined in response to the basis variable set  610  and the aftertreatment controller specification set  611 . The initial design reference value set  630  may be a best guess, such as a steady state reference value set. This set is provided to a predictive model  632 , which provides an output set  633 . An optimization routine  634  optionally constrains the design reference value set  630  in response to a threshold criteria set  626  and the output set  633 . The design reference value set  620  may be provided as a design reference value set for another iteration in the cycle or may be provided as a reference value set  620  when an output condition is met. In this way, the aftertreatment target determiner  604  is capable of generating an iteratively optimized reference value set  620 . 
       FIG. 10  is a schematic flow chart diagram of an example procedure  700  for controlling the aftertreatment system  120  of the engine system  100 , according to some embodiments. The procedure includes an operation  705  to interpret an aftertreatment basis variable set. The aftertreatment basis variable set is selected to characterize the majority of effects of the aftertreatment subsystem. In operation  710 , an aftertreatment specification set is interpreted. An example aftertreatment specification set defines the acceptable types of inputs and their range for a controller of the aftertreatment subsystem. 
     In operation  715 , an aftertreatment reference value set is determined in response to the aftertreatment basis variable set and the aftertreatment controller specification set. The aftertreatment reference value set is a set of target values for performance of the air handling subsystem. By including the aftertreatment controller specification set, the target values may be determined within acceptable ranges of the specification of one or more controllers of the aftertreatment subsystem to facilitate more accurate control of the aftertreatment subsystem. Operation  715  may include updating one or more predictive models and/or constraining an aftertreatment reference value set to meet various threshold criteria. In some embodiments, the aftertreatment controller specification set is included in the calibration of the aftertreatment reference value set in response to the aftertreatment basis variable set. 
     In operation  720 , an aftertreatment command set is determined in response to the aftertreatment reference value set. The aftertreatment command set may be the same as the aftertreatment reference value set. Alternatively or in combination, the aftertreatment reference value set may be modified to provide an aftertreatment command set. For example, the aftertreatment command set may be determined in response to constraints (or limitations) of the aftertreatment subsystem. In some embodiments, one or more constraints (e.g., physical, emissions, or otherwise) of the aftertreatment subsystem are included in calibration of the aftertreatment reference value set in response to the aftertreatment basis variable set. In such embodiments, the aftertreatment reference value set is optionally not modified in response to those constraints at run-time. 
     Finally, in operation  725 , exhaust is treated from an internal combustion engine in response to the aftertreatment command set. The treating step may include providing the aftertreatment command set to a controller of the aftertreatment subsystem. The controller of the aftertreatment system may operate components of the aftertreatment system, such as NO X  reductant fluid, to treat exhaust from the internal combustion engine. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other embodiments will be apparent to those of skill in the art upon reading and understanding the above description. For example, it is contemplated that features described in association with one embodiment are optionally employed in addition or as an alternative to features described in associate with another embodiment. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.