Coordination of torque interventions in MPC-based powertrain control

• US 10,119,481 B2
• Filed: 03/22/2017
• Issued: 11/06/2018
• Est. Priority Date: 03/22/2017
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Livshiz, Michael, Pattipati, Bharath, Whitney, Christopher E., Bernardini, Daniele, Bemporad, Alberto
• Primary Examiner(s): Kwon, John
• Assistant Examiner(s): Hoang, Johnny H
• Application Number:
  US15/465,647
• Publication Number:
  US 20180274453A1
• Time in Patent Office: 594 Days
• Field of Search: 701110-114
• CPC Class Codes: B60K 28/16 responsive to, or preventing, skidding of wheels brake control systems for vehicle drive stability B60T8/1755; arrangements responsive to a speed condition for adjusting wheel braking force B60T8/32; control of vehicle driving stability otherwise than by controlling the propulsion unit only B60W30/02; preventing wheel slippage by reducing power in rail vehicles B61C15/00
• CPC Class Codes: F02D 11/105 characterised by the function converting demand to actuation, e.g. a map indicating relations between an accelerator pedal position and throttle valve opening or target engine torque
• CPC Class Codes: F02D 2041/1412 using a predictive controller
• CPC Class Codes: F02D 2041/1433 using a model or simulation of the system
• CPC Class Codes: F02D 2200/0625 Fuel consumption, e.g. measured in fuel liters per 100 kms or miles per gallon
• CPC Class Codes: F02D 2200/1004 Estimation of the output torque
• CPC Class Codes: F02D 2200/602 Pedal position
• CPC Class Codes: F02D 2250/18 Control of the engine output torque
• CPC Class Codes: F02D 2250/26 by applying a torque limit
• CPC Class Codes: F02D 29/02 peculiar to engines driving vehicles; peculiar to engines driving variable pitch propellers
• CPC Class Codes: F02D 41/1402 Adaptive control
• CPC Class Codes: F02D 41/1406 with use of a optimisation method, e.g. iteration
• CPC Class Codes: F16H 61/0213 characterised by the method for generating shift signals
• CPC Class Codes: F16H 63/50 Signals to an engine or motor
• CPC Class Codes: F16H 63/502 for smoothing gear shifts

Abstract

A propulsion system, control system, and method are provided for optimizing fuel economy, which use model predictive control systems to generate a plurality of sets of possible command values and determine a cost for each set of possible command values of based on a first predetermined weighting value, a second predetermined weighting value, a plurality of predicted values, and a plurality of requested values. The set of possible command values having the lowest cost is determined and defined as a set of selected command values. Arbitration is performed including at least one of the following: A) determining at least one requested value based on arbitrating between a driver requested value and an intervention requested value; and B) determining a desired command value by arbitrating between a selected command value of the set of selected command values and a command intervention value.

Claims

1. A method for controlling a propulsion system of a motor vehicle, the method comprising:

generating a plurality of sets of possible command values;

determining a cost for each set of possible command values of the plurality of sets of possible command values based on a first predetermined weighting value, a second predetermined weighting value, a plurality of predicted values, and a plurality of requested values;

determining which set of possible command values of the plurality of sets of possible command values has a lowest cost; and

selecting the set of possible command values that has the lowest cost to define a set of selected command values;

performing an arbitration step comprising at least one of the following arbitration procedures A and B;

A) determining at least one requested value of the plurality of requested values based on arbitrating between a driver requested value and an intervention requested value; and

B) determining a desired command value by arbitrating between a selected command value of the set of selected command values and a command intervention value; and

controlling a vehicle parameter based on the desired command value.

2. The method of claim 1, wherein performing the arbitration step comprises performing both of the arbitrations procedures A and B.

3. The method of claim 2, wherein:

the plurality of sets of possible command values includes a plurality of commanded engine output torque values;

the set of selected command values includes a selected engine output torque value; and

the command intervention value includes an engine torque intervention value.

4. The method of claim 3, further comprising:

generating a plurality of predicted actual axle torque values and a plurality of predicted actual fuel consumption rate values based on the plurality of sets of possible command values, the plurality of sets of possible command values including a plurality of possible commanded transmission ratio values; and

determining the cost for each set of possible command values further based on a predicted actual axle torque value of the plurality of predicted axle torque values and a predicted actual fuel consumption rate value of the plurality of predicted actual fuel consumption rate values, the plurality of requested values including a driver axle torque requested, an engine output torque requested, a transmission ratio requested, and a fuel consumption rate requested.

5. The method of claim 4, further comprising determining the plurality of predicted actual axle torque values and the plurality of predicted actual fuel consumption rate values with the following set of equations:

6. The method of claim 5, further comprising:

determining that the desired command value is the engine torque intervention value after arbitrating between the selected command value of the plurality of selected command values and the engine torque intervention value; and

determining that Te_c_arb is equal to the engine torque intervention value.

7. The method of claim 5, further comprising determining the engine torque intervention value from among the following:

a transmission torque reduction request, an engine overspeed request, a boost request, a speed control request, an engine crank shutdown ring request, a power take off ring request, an exhaust O2 sensor ring request, a torque cut off ring request, a hybrid torque request, and a power take off control request.

8. The method of claim 7, further comprising:

determining an accelerator pedal position (PP);

determining an engine speed (RPM);

determining a vehicle speed (V);

determining an air-fuel ratio (AF);

determining the driver axle torque requested (Ta_dr) based on the accelerator pedal position (PP) and the vehicle speed (V);

determining an arbitrated axle torque requested (Ta_arb) by selecting a winner between the driver axle torque requested (Ta_dr) and the intervention requested value (A_i);

determining a transmission ratio requested (Rat_r) based on the arbitrated axle torque requested (Ta_arb) and the vehicle speed (V);

determining the engine output torque requested (Te_r) based on the arbitrated axle torque requested (Ta_arb), the transmission ratio requested (Rat_r), and a final drive ratio (FD); and

determining the fuel consumption rate requested (FR_r) based on the driver axle torque requested (Ta_dr), the vehicle speed (V), the engine speed (RPM), and the air-fuel ratio (AF),

wherein the plurality of requested values includes the driver axle torque requested (Ta_dr), the fuel consumption rate requested (FR_r), the engine output torque requested (Te_r), and the transmission ratio requested (Rat_r).

9. The method of claim 8, further comprising determining the intervention requested value from among the following:

a brake torque management request, a vehicle overspeed condition request, a traction control request, a deceleration fuel cut off request, a shaping request, a chassis system request, a performance launch request, a four wheel drive request, and an emergency autonomous braking request.

10. The method of claim 9, the plurality of selected command values including a selected transmission ratio command value, the method further comprising controlling a vehicle parameter based on at least one of the desired command values.

11. A control system for a propulsion system of a motor vehicle having a transmission and an engine, the control system comprising:

a command generator module configured to generate a plurality of sets of possible command values;

a cost module configured to;

determine a cost for each set of possible command values of the plurality of sets of possible command values based on a first predetermined weighting value, a second predetermined weighting value, a plurality of predicted values, and a plurality of requested values; and

determining which set of possible command values of the plurality of sets of possible command values has a lowest cost; and

a selection module configured to select the set of possible command values that has the lowest cost to define a set of selected command values;

an arbitration module configured to perform at least one of the following arbitration procedures A and B;

A) determine at least one requested value of the plurality of requested values based on arbitrating between a driver requested value and an intervention requested value; and

B) determine a desired command value by arbitrating between a selected command value of the set of selected command values and a command intervention value; and

an actuation module configured to control a vehicle parameter based on the desired command value.

12. The control system of claim 11, at least one selected command value of the set of selected command values being a selected engine output torque value, the command intervention value being an engine torque intervention value, the driver requested value being an driver axle torque requested, the arbitration module being an engine torque arbitration module configured to determine the desired command value by selecting a winner between the selected engine output torque value and the engine torque intervention value, the control system further comprising an axle torque arbitration module configured to determine an arbitrated axle torque requested by selecting a winner between the driver axle torque requested and the intervention requested value.

13. The control system of claim 12, further comprising a prediction module configured to generate a plurality of predicted actual axle torque values and a plurality of predicted actual fuel consumption rate values based on the plurality of sets of possible command values, the plurality of sets of possible command values including a plurality of possible commanded transmission ratio values and a plurality of possible commanded engine torque values, wherein the cost module is configured to determine the cost for each set of possible command values further based on a predicted actual axle torque value of the plurality of predicted axle torque values and a predicted actual fuel consumption rate value of the plurality of predicted actual fuel consumption rate values, the plurality of requested values including the driver axle torque requested, an engine output torque requested, a transmission ratio requested, and a fuel consumption rate requested.

14. The control system of claim 13, wherein the prediction module is configured to determine the plurality of predicted actual axle torque values and the plurality of predicted actual fuel consumption rate values with the following set of equations:

15. The control system of claim 14, wherein the engine torque arbitration module is configured to feed Te_c_arb back to the prediction module, the engine torque arbitration module being configured to determine the engine torque intervention value from among the following:

a transmission torque reduction request, an engine overspeed request, a boost request, a speed control request, an engine crank shutdown ring request, a power take off ring request, an exhaust O2 sensor ring request, a torque cut off ring request, a hybrid torque request, and a power take off control request.

16. The control system of claim 15, further comprising a steady state optimizer module configured to:

determine an accelerator pedal position (PP);

determine an engine speed (RPM);

determine a vehicle speed (V);

determine an air-fuel ratio (AF);

determine the driver axle torque requested (Ta_dr) based on the accelerator pedal position (PP) and the vehicle speed (V);

determine a transmission ratio requested (Rat_r) based on the arbitrated axle torque requested (Ta_arb) and the vehicle speed (V);

determine the engine output torque requested (Te_r) based on the arbitrated axle torque requested (Ta_arb), the transmission ratio requested (Rat_r), and a final drive ratio (FD); and

determine the fuel consumption rate requested (FR_r) based on the driver axle torque requested (Ta_dr), the vehicle speed (V), the engine speed (RPM), and the air-fuel ratio (AF).

17. The control system of claim 16, wherein the axle torque arbitration module is configured to determine the intervention requested value from among the following:

a brake torque management request, a vehicle overspeed condition request, a traction control request, a deceleration fuel cut off request, a shaping request, a chassis system request, a performance launch request, a four wheel drive request, and an emergency autonomous braking request.

18. The control system of claim 17, the plurality of selected command values including a selected transmission ratio command value, the control system further comprising an actuation module configured to control a vehicle parameter based on at least one of the desired command values.

19. A propulsion system for a motor vehicle, comprising:

an engine operable to power the motor vehicle, the engine having an engine output shaft configured to transfer engine output torque;

a continuously variable transmission having a variator assembly including a first pulley and a second pulley, the first and second pulleys being rotatably coupled by a rotatable member, at least one of the first and second pulleys including a movable sheave translatable along an axis to selectively change a transmission ratio between the engine output shaft and a transmission output shaft;

a drive axle configured to be driven via the transmission output shaft, the drive axle being configured to output axle torque to a set of wheels; and

a control system comprising;

a prediction module configured to generate a plurality of predicted actual axle torque values and a plurality of predicted actual fuel consumption rate values based on a plurality of sets of possible command values, the plurality of sets of possible command values including a plurality of possible commanded transmission ratio values and a plurality of possible commanded engine torque values;

a cost module configured to;

determine a cost for each set of possible command values of the plurality of sets of possible command values based on a predicted actual axle torque value of the plurality of predicted axle torque values, a predicted actual fuel consumption rate value of the plurality of predicted actual fuel consumption rate values, a first predetermined weighting value, a second predetermined weighting value, and a plurality of requested values, the plurality of requested values including the driver axle torque requested, an engine output torque requested, a transmission ratio requested, and a fuel consumption rate requested; and

determine which set of possible command values of the plurality of sets of possible command values has a lowest cost;

a selection module configured to select the set of possible command values that has the lowest cost to define a set of selected command values;

an axle torque arbitration module configured to determine at least one requested value of the plurality of requested values based on arbitrating between a driver axle torque requested and an axle intervention requested value;

an engine torque arbitration module configured to determine a desired command value by arbitrating between a selected engine torque command value of the set of selected command values and an engine torque command intervention value; and

an actuation module configured to control a vehicle parameter based on the desired command value.

20. The propulsion system of claim 19, wherein the prediction module is configured to determine the plurality of predicted actual axle torque values and the plurality of predicted actual fuel consumption rate values with the following set of equations: