Multivariable control system for setpoint design
View Patent ↗A system and approach for development of setpoints for a controller of an engine or powertrain. The controller may be parametrized as a function of setpoints to provide performance variables that are considered acceptable by a user or operator for normal operating conditions of the engine or powertrain. With each iteration of the setpoints, the controller may be reconfigured to provide more stable and dynamically performant control of the engine or powertrain. The present system and approach may automate a previously labor intensive approach for designing setpoints for the controller.
1. A system for setpoint determination, comprising:
an engine and/or aftertreatment system having a first input comprising exogenous signals and a first output comprising performance variables; and
a controller having a second input comprising measured feedback variables from the engine, a third input comprising setpoints, and a second output comprising actuator signals for the engine; and
wherein:
a map is constructed of actuator positions that deliver certain performance variables from data of a mapping of the engine over a predetermined period of time;
setpoints in r for the controller are initialized from the map;
the controller is calibrated towards the engine and/or an iteration of setpoints in r; and
y comprises measured feedback variables from the engine.
2. The system of claim 1 , wherein with each iteration of setpoints, the controller is reconfigured to provide stable and dynamically performant control of the engine.
3. The system of claim 2 , wherein a reconfiguration of the controller comprises a semi-automatic generation of the controller in which a change in setpoints is followed by a re-linearization of an engine model, followed by an automatic redesign of a controller as a function of a linearized model.
4. The system of claim 1 , wherein the setpoints are changed until the performance variables are deemed acceptable by a user or operator for normal operating conditions of the engine.
5. The system of claim 1 , wherein when the controller is calibrated towards the engine and/or an iteration of setpoints in r, a calibrated control of the engine can be considered as complete and then a transfer to a next phase, such as certification, can occur.
6. The system of claim 1 , wherein an iteration of setpoints comprises:
the setpoints being varied and resulting in corresponding changes of the performance variables; and
a calculation being derived from variations of the setpoints and corresponding changes of the performance variables; and
wherein the calculation results in a recommended change to the setpoints.
7. The system of claim 1 , wherein:
exogenous signals comprise one or more items comprising engine speed, fueling rate, ambient temperature, ambient air pressure, pedal position, and/or pedal change rate;
measured feedback variables comprise one or more on-engine measurements comprising compressor boost pressure, compressor flow, MAP, MAF, EGR flow, MAT, temperatures, emissions, lambda sensor indications, exhaust manifold pressure, total engine air flow, turbocharger speed, engine sensors, emission sensors, after-treatment sensors, NOx concentration, and/or exhaust gas temperature;
actuator signals comprise one or more items comprising variable geometry turbine (VGT) vanes, high pressure or low pressure exhaust gas recirculation (EGR) valves, throttle valves, fuel injection specifications, start of injection (SOI) timing variable valve actuation (VVA), wastegate valve, urea dosing, and/or post-injection of fuel for DPF regeneration;
performance variables comprise one or more items pertaining to specific fuel consumption, general emissions, NOx, NH3, PM, HC, and/or CO2; and
setpoints comprise one or more items pertaining to measured feedback variables, MAP, MAF, EGR flow, air-fuel ratio, pressures, flows, temperatures, NOx, upper and lower limits of actuator positions, a limit for lambda indication, a limit for turbocharger speed, and/or so forth.
8. A method for determining setpoints for an engine system, comprising:
building a control-oriented model of an engine system;
designing a feedback controller parametrized as a function of setpoints;
designating a starting setpoint as a nominal setpoint;
observing performance of the engine in terms of quality variables;
introducing a series of steps in the setpoints as enabled by the feedback controller;
allowing a closed loop of the feedback controller and engine and/or aftertreatment system to come to equilibrium at each position of setpoints, recording values of the quality variables at each position of setpoints;
building and calibrating a model from the values to express the quality variables as a function of setpoints; and
changing the setpoints to affect the quality variables; and
wherein:
the quality variables comprise one or more items comprising specific fuel consumption and/or an array of emissions; and
the setpoints pertain to one or more items comprising measured sensor variables.
9. The method of claim 8 , further comprising observing engine performance in view of the quality variables.
10. The method of claim 9 , wherein the engine system comprises an engine and an after-treatment subsystem.
11. The method of claim 9 , wherein:
n=a number of quality variables;
r=setpoints;
z=quality variables;
r*=newer derived setpoints;
r
*
=
arg
min
r
(
ρ
1
f
1
(
r
)
+
…
+
ρ
n
f
n
(
r
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;
which is an optimization formula; and
the weights (ρ) are tuned.
12. The method of claim 9 , wherein:
n=a number of quality variables;
r=setpoints;
z=quality variables;
z target =user-specified desired quality variables;
r*=newer derived setpoints;
r
*
=
arg
min
r
(
z
1
target
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f
1
(
r
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z
n
target
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f
n
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r
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which is an optimization formula; and
the targets are changed to affect setpoints.
13. The method of claim 8 , further comprising:
implementing newly derived setpoints into a controller of the engine;
observing values of the quality variables; and
repeating steps of claims 8 and 11 until the values of the quality variables are acceptable to a user or operator of the engine system.
14. The method of claim 8 , further comprising:
implementing newly derived setpoints into a controller of the engine;
observing values of the quality variables; and
repeating steps of claims 8 and 12 until the values of the quality variables are acceptable to a user or operator of the engine system.
15. A system of multivariable control for setpoint determination comprising:
an engine and/or aftertreatment system;
a controller connected to the engine and/or aftertreatment system;
data from mapping the engine performed over a time period;
a map of actuator positions for the engine relative to performance variables constructed from the data; and
one or more maps of setpoints for the controller of the engine initialized from the map; and
wherein the controller is automatically calibrated towards the engine and/or setpoints of the one or more maps, specified in measured feedback variables from the engine to the controller.
16. The system of claim 15 , wherein an iteration of setpoints comprises:
the setpoints being perturbed and resulting an effect on the performance variables; and
a calculation incorporating information about the setpoints being perturbed and resulting the effect on the performance variables, is run to indicate one or more changes recommended for the setpoints.
17. The system of claim 16 , wherein with an implementation of the one or more changes recommended by an iteration of setpoints for the setpoints, the controller is automatically reconfigured to provide a stable and dynamically performant control of the engine for the new setpoints.
18. The system of claim 17 , wherein:
the setpoints are iterated until a predetermined level of performance is achieved by the closed-loop system; and
the controller is reconfigured with each iteration of the setpoints; and
when the predetermined level of performance of the engine and/or aftertreatment system is achieved, a multivariable control for setpoint determination is considered complete and a transfer to a next phase, such as certification, occurs.
19. The system of claim 16 , wherein the performance variables comprise one or more items comprising specific fuel consumption and/or emissions.
20. The system of claim 19 , wherein setpoints are changed according to the one or more changes recommended for the setpoints until the performance variables are deemed acceptable by a user or operator for normal operating conditions of the engine.