THE MOM UNHOIHINTO US009789876B1

(12) United States Patent ( 10) Patent No.: US 9,789,876 B1

Livshiz et al. (45) Date of Patent: Oct. 17, 2017
(54 ) MOTOR
AXLE TORQUE CONTROL SYSTEM FOR A
VEHICLE
(56 ) References Cited
U .S . PATENT DOCUMENTS
( 71 ) Applicant: GM Global Technology Operations 6 , 173,226 B1 * 1/2001 Yoshida ............... B60W 10 /06
LLC , Detroit, MI (US ) 477 / 105
7 ,222,012 B2* 5/2007 Simon, Jr. ........... B60W47710/107
/06
(72 ) Inventors: Michael Livshiz , Ann Arbor,MI (US); 7 ,433,775 B2 10 /2008 Livshiz
Christopher E . Whitney , Commerce , 7 ,563 ,194 B2 * 7 / 2009 Murray ............... B60W 10/06
MI (US); Kevin C . Wong, Canton , MI 477/ 40
(US ); Daniele Bernardini, Siena (IT ); 7 ,698 ,048 B2 * 4 /2010 Jung ........ ............ FO2D 41/ 102
Alberto Bemporad , Lucca (IT ) 477 / 120
8 ,078 ,371 B2 * 12 /2011 Cawthorne ............. BOOK 6 /40
(73 ) Assignee : GM GLOBAL TECHNOLOGY 180 /65 . 28
OPERATIONS LLC , Detroit, MI (US) 8, 121,763 B2 * 2/2012 Hou .................. B60W 30 /1882
701/51
8 ,219 ,304 B2 * 7 /2012 Soma ...................... B60L 11/ 14
( * ) Notice : Subject to any disclaimer , the term of this 477 / 3
patent is extended or adjusted under 35 8,744 ,716 B2 * 6 /2014 Kar ...................... FO2D 11/ 105
U .S .C . 154 (b ) by 0 days. 701/ 110
8 ,977,457 B2* 3 /2015 Robinette ............. B60W 10/02
477 / 166
( 21) Appl. No .: 15 /184 ,706 (Continued )
ã Primary Examiner — Dirk Wright
( 22 ) Filed : Jun . 16 , 2016 (57) APAT
ABSTRACT
(51) Int. CI. A powertrain control system for a motor vehicle having a
GO6F 17 /00 ( 2006 .01) transmission and an engine includes an axle torque control
ler that determines a desired engine torque and a desired
B60W 30 /188 ( 2012 . 01) speed ratio from a plurality of inputs , an engine controller
B60W 10 /06 (2006 .01) that determines a commanded engine torque based on the
B60W 10 /11 ( 2012 .01) desired engine torque, wherein the commanded engine
(52) U .S . CI. torque is used to control the engine to produce an actual
CPC .......... . B60W 30 / 188 ( 2013.01); B60W 10 / 06 engine torque, a transmission controller that determines a
(2013 .01 ); B60W 10 / 11 (2013 .01) ; B60W commanded gear ratio based on the desired gear ratio ,
2510 /0623 ( 2013 .01); B60W 2520 / 10 wherein the commanded gear ratio is used to control the
(2013.01); B60W 2540 / 10 (2013.01) ; B60W transmission to produce an actual gear ratio , and an estima
2710 /0666 (2013 .01); B60W 2710 / 1005 tor that determines an actual axle torque of themotor vehicle
(2013.01) from the actual engine torque and the actual gear ratio . The
(58 ) Field of Classification Search plurality of inputs includes a desired axle torque , the actual
None axle torque, a desired fuel rate , an actual fuel rate .
See application file for complete search history . 21 Claims, 3 Drawing Sheets

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howwith

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 US 9 ,789,876 B1
Page 2

( 56 ) References Cited
U . S . PATENT DOCUMENTS
9 ,067,593 B2 * 6 / 2015 Dufford ................ B60W 10 /06
2007/0191181 A1 * 8/ 2007 Burns .. ..... ...... B60W 10 / 08
477 /40
2015 /0315767 A1 * 11/ 2015 Miyamoto ........ E02F 3 /283
701/50
* cited by examiner
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 US 9,789,876 B1
AXLE TORQUE CONTROL SYSTEM FOR A In another aspect, the engine inputs include a maximum
MOTOR VEHICLE engine torque , a minimum engine torque, a maximum
change in engine torque, and a minimum change in engine
TECHNICAL FIELD torque .
5 In another aspect, the axle controller limits the desired
The invention relates to an axle torque control system for engine torque to be less than the maximum engine torque
a motor vehicle having an engine and a transmission , and and greater than the minimum engine torque , and limits a
more particularly to an axle torque control system for a change in the desired engine torque to be less than the
motor vehicle that uses a multivariable controller. maximum change in engine torque and greater than the
" minimum change in engine torque .
BACKGROUND In another aspect, the transmission inputs include a maxi
mum gear ratio , a minimum gear ratio , a maximum change
Powertrain control in a motor vehicle generally involves in gear ratio , and a minimum change in gear ratio .
reading driver and vehicle inputs, such as accelerator pedal 16 In another aspect, the axle controller limits the desired
position , vehicle sensor data, torque requests , and commu gear ratio to be less than the maximum gear ratio and greater
nicating these inputs to an Engine Control Module (ECM ) than the minimum gear ratio , and limits a change in the
and a Transmission Control Module (TCM ). The ECM desired gear ratio to be less than the maximum change in
calculates a desired axle torque from the driver and vehicle gear ratio and greater than the minimum change in gear
inputs . The desired axle torque is then communicated to the 20 ratio .
engine and to the TCM . The engine is controlled based on In another aspect , the desired axle torque is determined
the desired axle torque to produce an actual axle torque . from a vehicle accelerator pedal position sensed from a
Meanwhile , the TCM calculates a desired speed or gear ratio vehicle pedal sensor and a vehicle speed sensed from a
from the desired axle torque and the vehicle speed . The vehicle speed sensor.
desired gear ratio is then communicated to the transmission . 25 Further features , aspects and advantages of the present
The transmission is controlled based on the desired gear invention will become apparent by reference to the follow
ratio to produce an actual gear ratio . The actual axle torque ing description and appended drawings wherein like refer
and the actual gear ratio define the operating conditions of ence numbers refer to the same component, element or
the motor vehicle . feature .
While this system of powertrain control is useful for its 30
intended purpose , there is room in the art for improvements BRIEF DESCRIPTION OF THE DRAWINGS
in powertrain control that provide dynamic control of the
axle torque to balance performance and fuel economy, The drawings described herein are for illustration pur
especially in powertrains having a continuously variable poses only and are not intended to limit the scope of the
transmission or stepped transmissions with multiple gears. 35 present disclosure in any way .
FIG . 1 is a schematic diagram of an exemplary powertrain
SUMMARY in a motor vehicle ;
FIG . 2 is a schematic diagram of a powertrain control
A powertrain control system for a motor vehicle having a system for use with the motor vehicle ; and
transmission and an engine is provided . The powertrain 40 FIG . 3 is a schematic diagram of a controlmethod for use
control system includes an axle torque controller that deter - with the power control system .
mines a desired engine torque and a desired speed ratio from
a plurality of inputs , an engine controller that determines a DESCRIPTION
commanded engine torque based on the desired engine
torque , wherein the commanded engine torque is used to 45 With reference to FIG . 1 , an exemplary motor vehicle is
control the engine to produce an actual engine torque , a shown and generally indicated by reference number 5 . The
transmission controller that determines a commanded gear motor vehicle 5 is illustrated as a passenger car, but it should
ratio based on the desired gear ratio , wherein the com be appreciated that themotor vehicle 5 may be any type of
manded gear ratio is used to control the transmission to vehicle , such as a truck , van , sport- utility vehicle , etc . The
produce an actual gear ratio , and an estimator that deter - 50 motor vehicle 5 includes an exemplary powertrain 10 . It
mines an actual axle torque of the motor vehicle from the should be appreciated at the outset that while a rear-wheel
actual engine torque and the actual gear ratio . The plurality drive powertrain has been illustrated , the motor vehicle 5
of inputs includes a desired axle torque, the actual axle may have a front-wheel drive powertrain without departing
torque , a desired fuel rate , an actual fuel rate . from the scope of the present disclosure . The powertrain 10
In one aspect, the axle torque controller is a multivariable 55 generally includes an engine 12 interconnected with a trans
controller that optimizes the desired fuel rate and the desired mission 14 and a final drive unit 16 .
axle torque . The engine 12 may be a conventional internal combustion
In another aspect, the axle torque controller includes a engine or an electric engine, hybrid engine , or any other type
cost function based on the desired axle torque, the desired of prime mover, without departing from the scope of the
fuel rate , the actual axle torque, and the actual fuel rate , and 60 present disclosure . The engine 12 supplies a driving torque
wherein the cost function is minimized . to the transmission 14 via a crankshaft 18 . The driving
In another aspect, the axle torque controller is one of a torque may be transmitted through a flexplate and/ or starting
linear quadratic controller, a quasi- linear controller, or a device 20 to the transmission 14 . The starting device 20 may
model predictive controller. be a hydrodynamic device , such as a fluid coupling or torque
In another aspect, the plurality of inputs further includes 65 converter, a wet dual clutch , or an electric motor. Torque is
engine inputs from the engine controller and transmission then transmitted from the starting device to at least one
inputs from the transmission controller. transmission input shaft 22 .
 US 9,789, 876 B1
The transmission 14 may be a stepped transmission sensor S8 communicate with the transmission controlmod
having planetary gears, a countershaft transmission, a con ule 40. The vehicle speed sensor S10 and the pedal position
tinuously variable transmission , or an infinitely variable sensor S12 communicate with both the engine control mod
transmission . Torque from the transmission input shaft 22 is ule 38 and the transmission control module 40 .
communicated through a ratio control unit 24 to a transmis - 5 With reference to FIG . 3 , and continued reference to
sion output shaft 26 . Generally, the ratio control unit 24 FIGS. 1 and 2 . a control diagram of the powertrain control
includes gears , shafts , countershafts, clutches , brakes , and/ or system 34 is illustrated . The control diagram illustrates a
synchronizers that are selectively engageable to provide a control system ormethod 100 for generating an actual axle
plurality of forward or reverse speed or gear ratios between torque Ta , and actual fuel consumption rate FR , by opti
the transmission input shaft 22 and the transmission output 10 mizing a desired ( reference ) axle torque Ta refand a desired
shaft 26 . Where the transmission 14 is a continuously fuel consumption rate FRret The actual axle torque Ta a is
variable transmission , the ratio control unit 24 may include the amount of actual torque at the vehicle axle 30 . The actual
an endless member wrapped around variable diameter pul fuel rate FR , is the actual rate of fuel consumption by the
leys.
The transmission output shaft 26 communicates output 15 motor vehicle 5 . The actual fuel rate FR , may be determined
torque to the final drive unit 16 , either through direct gearing from an estimate of air flow , for example based on data from
or a chain drive . The final drive unit 16 generally includes the air flow sensor S2. The desired axle torque Ta ref is the
a differential 28 that transfers torque through axles 30 to amount of torque needed at the vehicle axle 30 to fulfill a
drive wheels 32. driver ' s intent for acceleration or deceleration . The desired
Turning now to FIG . 2 , a powertrain control system for 20 axle torque Ta ref is determined from a lookup table or 2D
use with the exemplary powertrain 10 is generally indicated map from a vehicle speed sensed by vehicle speed sensor
by reference number 34 . The powertrain control system 34 S10 and an accelerator pedal position sensed by the pedal
includes a supervisory control module 36 in electronic position sensor S12 . The desired fuel rate FR ef is a desired
communication with an engine control module 38 and a rate .
transmission controlmodule 40 . Themodules 36 , 38 , and 40 25 The control system 100 includes an axle torque controller
may communicate through a vehicle network or cable area 102, an engine controller 104 , a transmission controller 106 ,
network (CAN ) bus. The powertrain control system 34 may and an estimator 108 . In a preferred embodiment, the axle
include or communicate with various other controlmodules , torque controller 102 is stored and executed by the super
such as a body control module or infotainment control
module. Alternatively, the supervisory control module 36 30 visory
and
controlmodule 34 , the engine controller 104 is stored
executed by the engine control module 36 , and the
may be subsumed within the engine control module 38 or transmission controller 106 is stored and executed by the
transmission control module 40 .
The supervisory control module 36 is a non - generalized , transmission control module 40 . The estimator 108 is pref
erably stored and executed by the engine controlmodule 36
electronic control device having a preprogrammed digital 5 but may be stored and executed by any control module .
computer or processor 42 , memory or non -transitory com - 35 The
puter readablemedium 44 used to store data such as control troller axle torque controller 102 is any multivariable con
capable of optimizing the desired fuel rate FR and
logic , instructions, image data , lookup tables, etc ., and a
plurality of input/output peripherals or ports 46 . The pro the desired axle torque Ta re based on a plurality of inputs.
cessor 42 is configured to execute the control logic or The axle torque controller 102 may be , for example , a linear
instructions. 40 quadratic controller, a quasi-linear controller, or a model
The engine control module 38 is a non - generalized , predictive controller, to name but a few . The plurality of
electronic control device having a preprogrammed digital inputs include the actual axle torque Ta _ a, the desired axle
computer or processor 48, memory or non -transitory com torque Ta refh the actual fuel rate FR?, and the desired fuel
puter readable medium 50 used to store data such as control rate FR ref: The axle torque controller 102 determines a
logic , instructions, image data , lookup tables , etc ., and a 45 desired brake engine torque Teref and a desired gear ratio
plurality of input/output peripherals or ports 52 . The pro - Ref from the optimized values. The desired brake engine
cessor 48 is configured to execute the control logic or torque Tref is the desired engine torque on the crankshaft
instructions. The engine control module 38 communicates 18 and the desired gear ratio Rrefis the desired gear ratio to
with , and controls, the engine 12 . be provided by the transmission 14 . By way of example , a
The transmission control module 40 is a non - generalized , 50 linear quadratic controller may be used having a system
electronic control device having a preprogrammed digital described by the formula :
computer or processor 54 , memory or non -transitory com
puter readable medium 56 used to store data such as control y > = 4y + Bu (1)
logic, instructions, image data , lookup tables, etc., and a Where A and B are parameters of the system determined
plurality of input/output peripherals or ports 58 . The pro - 55 through testing, physical models , etc . The quadratic cost
cessor 54 is configured to execute the control logic or function is defined as follows:
instructions . The transmission control module 40 commu
nicates with , and controls , the transmission 14 . cost=f( ref- y)?.R•(y_ ref-y) (2)
The powertrain control system 34 communicates with a
plurality of sensors connected to the powertrain 10 including 60 Where R is a cost function parameter. The variables y, y reto
an air flow sensor S2 in the engine 12 , an engine speed and u are defined as follows:
sensor S4 , a transmission input shaft speed sensor S6 , a
transmission output shaft speed sensor S8 , a vehicle speed
sensor S10 , and a pedal position sensor S12 . The air flow y = || SFRTaa ] @

sensor S2 and the engine speed sensor S4 communicate with 65

the engine controlmodule 38 . The transmission input shaft
speed sensor S6 and the transmission output shaft speed
 US 9 ,789,876 B1
desired brake engine torque Te ref and the desired gear ratio
STa_ ref 1 (4) Ref. The system 100 repeats to provide dynamic , up to date
Yref | SFRref ] control ofthe actual axle torque of the motor vehicle 5 while
optimizing the fuel consumption rate of the vehicle .
The description of the invention is merely exemplary in
nature and variations that do not depart from the general
essence of the invention are intended to be within the scope
- |STSRref_ref ]
U =
(5 ) of the invention . Such variations are not to be regarded as a
departure from the spirit and scope of the invention .
10
The following is claimed :
The feedback control equation which minimizes the cost 1. A powertrain control system for a motor vehicle having
function is defined as follows: a transmission and an engine, the powertrain control system
u = - Ky comprising:
Where K is the matrix gain of the system . Thus, by 15 an axle torque controller that determines a desired engine
optimizing the cost of the system for fuel rate and accelera
torque and a desired speed ratio from a plurality of
inputs;
tion , the desired brake engine torque Te ref and the desired an engine controller that determines a commanded engine
gear ratio Reef are determined . torque based on the desired engine torque , wherein the
The axle torque controller 102 receives system limitations 20 commanded engine torque is used to control the engine
from the engine controller 104 including a maximum brake to produce an actual engine torque ;
engine torque Te max, a minimum brake engine torque a transmission controller that determines a commanded
Te_min , a maximum change in brake engine torque Te_max? gear ratio based on the desired gear ratio , wherein the
and a minimum change in brake engine torque Te min . The commanded gear ratio is used to control the transmis
axle torque controller 10 subjects the desired brake engine 25 sion to produce an actual gear ratio ; and
torque Te ref and the change in the desired brake engine an estimator that determines an actual axle torque of the
torque dTe ref to the following limitations: motor vehicle from the actual engine torque and the
Te_minsTeresle_max (7) actual gear ratio ,
wherein the plurality of inputs includes a desired axle
dTe_minsTeresdle_max (8) 30 torque, the actual axle torque, a desired fuel rate , an
actual fuel rate .
The axle torque controller 102 also receives system
limitations from the transmission controller 106 including a 2 . The powertrain control system of claim 1 wherein the
maximum gear ratio Rmar, a minimum gear ratio Rmin , a axle torque controller is a multivariable controller that
maximum change in gear ratio dR mar , and a minimum optimizes the desired fuel rate and the desired axle torque .
change in gear ratio SR . The axle torque controller 10 35 3 . The powertrain control system of claim 2 wherein the
axle torque controller includes a cost function based on the
subjects the desired gear ratio Rrer and the change in the desired
desired gear ratio dRrer to the following limitations: axle torque , the desired fuel rate , the actual axle
RminsRyessRmax torque , and the actual fuel rate, and wherein the cost function
(9) is minimized.
40 4 . The powertrain control system of claim 2 wherein the
dRmin SdRyesdRmax (10) axle torque controller is one of a linear quadratic controller,
The desired brake engine torque Terefis communicated to a quasi-linear controller , or a model predictive controller.
the engine controller 104 . The engine controller 104 may be 5 . The powertrain control system of claim 1 wherein the
any type of controller that provides a commanded brake plurality of inputs further includes engine inputs from the
engine torque Te based on the desired brake engine torque 45 engine controller and transmission inputs from the transmis
Te ref. The commanded brake engine torque Te is used to sion controller.
control the engine 12 to provide an actual brake engine 6 . The powertrain control system of claim 5 wherein the
torque Te a that is the brake engine torque actually commu engine inputs include a maximum engine torque, a minimum
nicated to the transmission 14 . engine torque, a maximum change in engine torque, and a
The desired gear ratio Rref is communicated to the trans - 50 minimum change in engine torque.
mission controller 106 . The transmission controller 106 may 7 . The powertrain control system of claim 6 wherein the
be any type of controller that provides a commanded gear axle controller limits the desired engine torque to be less
ratio R based on the desired gear ratio Rret. The commanded than the maximum engine torque and greater than the
gear ratio R is used to control the transmission 14 to provide minimum engine torque , and limits a change in the desired
an actual gear ratio R , between the transmission input shaft 55 engine torque to be less than themaximum change in engine
22 and the transmission output shaft 26 . torque and greater than the minimum change in engine
The estimator 108 then determines or estimates the actual torque .
axle torque Ta a based on the actual brake engine torque 8 . The powertrain control system of claim 5 wherein the
Te as the actual gear ratio R?, and losses associated with the transmission inputs include a maximum gear ratio , a mini
system . The actual brake engine torque Te may be sensed 60 mum gear ratio , a maximum change in gear ratio , and a
form the engine torque sensor S4 . The actual gear ratio Ra minimum change in gear ratio .
may be determined from the speed of the transmission input 9 . The powertrain control system of claim 8 wherein the
shaft 22 sensed by the transmission input shaft speed sensor axle controller limits the desired gear ratio to be less than the
S6 and the speed of the transmission output shaft 26 sensed maximum gear ratio and greater than the minimum gear
by the transmission output shaft speed sensor S8 . The actual 65 ratio , and limits a change in the desired gear ratio to be less
axle torque Te , is then communicated back to the axle than the maximum change in gear ratio and greater than the
torque controller 102 to be used in the determination of the minimum change in gear ratio .
 US 9, 789,876 B1
10 . The powertrain control system of claim 1 wherein the 17. The method of claim 11 further comprising limiting
desired axle torque is determined from a vehicle accelerator the desired gear ratio to a value within a gear ratio range.
pedal position sensed from a vehicle pedal sensor and a 18 . Themethod of claim 11 further comprising limiting a
vehicle speed sensed from a vehicle speed sensor. change in the desired gear ratio to a value within a change
11 . A method for
vehicle comprising :
controlling a powertrain
powertrain of
01 a
a motor
motor 5
5 inin gear ratio range .
determining a desired axle torque; 19 . The method of claim 11 wherein the desired axle
desired gear
determining a desired engine torque and a desired geartorque isis determined
torque de from an accelerator pedal position and
ratio based on the desired axle torque and a plurality ofa vehicle speed .
inputs ; 20 . A method for controlling a powertrain of a motor
determining a commanded axle torque based on the vehicle using a supervisory control module, the powertrain
desired engine torque ; having an engine controlled by an engine control module
controlling the engine to produce an actual engine torque and a transmission controlled by a transmission control
using the commanded engine torque ; module, the method comprising :
determining a commanded gear ratio based on the desired 155 determining , by the supervisory control module, a desired
gear ratio ; axle torque from a vehicle pedal position and a vehicle
controlling the transmission to produce an actual gear speed ;
ratio using the commanded gear ratio ; determining , by the supervisory controlmodule, a desired
estimating an actual axle torque based on the actual engine torque and a desired gear ratio based on the
engine torque and the actual gear ratio ; and desired axle torque and a plurality of inputs ;
communicating the actual axle torque to the supervisory 20 determining , by the engine control module , a commanded
control module as one of the plurality of inputs.
12 . The method of claim 11 further comprising determin axle torque based on the desired engine torque ;
ing a desired fuel rate and an actual fuel rate , and wherein controlling the engine to produce an actual engine torque
the plurality of inputs further includes the desired fuel rate using the commanded engine torque ;
and the actual fuel rate. 25
25 determining , by the transmission control module, a com
13 . The method of claim 12 wherein determining the manded gear ratio based on the desired gear ratio ;
desired engine torque and the desired gear ratio includes controlling the transmission to produce an actual gear
using a multivariable controller to optimize the desired axle ratio using the commanded gear ratio ;
torque and the desired fuel rate . estimating, by the engine control module , an actual axle
14 . The method of claim 12 wherein the multivariable 30 torque based on the actual engine torque and the actual
controller is one of a linear quadratic controller, a quasi gear ratio ; and
linear controller, or a model predictive controller. communicating the actual axle torque to the supervisory
15 . The method of claim 11 further comprising limiting control module as one of the plurality of inputs.
the desired engine torque to a value within a torque engine 21 . The method of claim 20 further comprising determin
range. 35 ing a desired fuel rate and an actual fuel rate , and wherein
16 . The method of claim 11 further comprising limiting a the plurality of inputs further includes the desired fuel rate
change in the desired engine torque to a value within a and the actual fuel rate .
change in torque range . * * * * *