Title of Invention

CONTROL ARCHITECTURE AND METHOD FOR TWO-DIMENSIONAL OPTIMIZATION OF INPUT SPEED AND INPUT AND INPUT POWER INCLUDING SEARCH WINDOWING

Abstract A microprocessor driven two dimensional search engine examines transmission operating points within a plurality of search range spaces and assists in determining properties associated with the driveline at various operating points within the space. The size of the space is reduced by rearrangement of data.
Full Text CONTROL ARCHITECTURE AND METHOD FOR TWO-DIMENSIONAL
OPTIMIZATION OF INPUT SPEED AND INPUT POWER INCLUDING
SEARCH WINDOWING
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional Application
No. 60/985,227 filed on 11/3/2007, which is hereby incorporated herein by
reference.
TECHNICAL FIELD
[0002] This disclosure relates generally to control systems for electro-
mechanical transmissions.
BACKGROUND
[0003] The statements in this section merely provide background
information related to the present disclosure and may not constitute prior art.
[0004] Known powertrain architectures include torque-generative devices,
including internal combustion engines and electric machines, which transmit
torque through a transmission device to an output member. One exemplary
powertrain includes a two-mode, compound-split, electro-mechanical
transmission which utilizes an input member for receiving motive torque from
a prime mover power source, preferably an internal combustion engine, and an
output member. The output member can be operatively connected to a
driveline for a motor vehicle for transmitting tractive torque thereto. Electric
machines, operative as motors or generators, generate a torque input to the


transmission, independently of a torque input from the internal combustion
engine. The electric machines may transform vehicle kinetic energy,
transmitted through the vehicle driveline, to electrical energy that is storable in
an electrical energy storage device. A control system monitors various inputs
from the vehicle and the operator and provides operational control of the
powertrain, including controlling transmission operating state and gear
shifting, controlling the torque-generative devices, and regulating the electrical
power interchange among the electrical energy storage device and the electric
machines to manage outputs of the transmission, including torque and
rotational speed.
SUMMARY
[0005] A method for decreasing the size of a space from within which a two-
dimensional search engine selects points defined by numerical pairs for
evaluation, the space including at least one two-dimensional first region, the
first region having minimum and maximum abscissa and ordinate values
associated with it, includes generating a plurality of contour plots, the contour
plots having abscissa and ordinate axes, and including contours which are
representative of a property associated with points within the first region
bounded by the abscissa and ordinate axes, selecting a second region from
each of the contour plots, the second regions each comprising minimum and
maximum abscissa values and minimum and maximum ordinate values,
providing four tables of data, the data in each table of the four tables including
one of four variables selected from the group consisting of: the minimum
abscissa value, the maximum abscissa value, the minimum ordinate value, and


the maximum ordinate value, providing a two-dimensional input request,
extracting a value for each of the minimum abscissa value, the maximum
abscissa value, the minimum ordinate value, and the maximum ordinate value
from the tables, to provide extracted values based upon the input request;, and
defining a search space based on the extracted values.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] One or more embodiments will now be described, by way of
example, with reference to the accompanying drawings, in which:
[0007] FIG. 1 is a schematic diagram of an exemplary powertrain, in
accordance with the present disclosure;
[0008] FIG. 2 is a schematic diagram of an exemplary architecture for a
control system and powertrain, in accordance with the present disclosure;
[0009] FIGS. 3 - 8 are schematic flow diagrams of various aspects of a
control scheme, in accordance with the present disclosure;
[0010] FIG. 9 is a schematic power flow diagram, in accordance with the
present disclosure;
[0011] FIG. 10 illustrates one embodiment of a two-dimensional search
range or space, which may be a region definable by coordinate axes with
associated minimum and maximum abscissa and ordinate values, in
accordance with the present disclosure;
[0012] FIG. 11 shows a contour plot of energy losses associated with
operating points for a transmission as described herein, in accordance with the
present disclosure; and

[0013] FIG. 12 shows one arrangement of data from a plurality of contour
plots, in accordance with the present disclosure.
DETAILED DESCRIPTION
[0014] Referring now to the drawings, wherein the showings are for the
purpose of illustrating certain exemplary embodiments only and not for the
purpose of limiting the same, FIG. 1 shows an exemplary electro-mechanical
hybrid powertrain. The exemplary electro-mechanical hybrid powertrain
shown in FIG. 1 comprises a two-mode, compound-split, electro-mechanical
hybrid transmission 10 operatively connected to an engine 14, and first and
second electric machines ('MG-A') 56 and ('MG-B') 72. The engine 14 and
first and second electric machines 56 and 72 each generate power which can
be transmitted to the transmission 10. The power generated by the engine 14
and the first and second electric machines 56 and 72 and transmitted to the
transmission 10 is described in terms of input torques, referred to herein as Ti,
TA, and TB respectively, and speed, referred to herein as Ni, NA, and NB,
respectively.
[0015] In one embodiment, the exemplary engine 14 comprises a multi-
cylinder internal combustion engine which is selectively operative in several
states to transmit torque to the transmission 10 via an input shaft 12, and can
be either a spark-ignition or a compression-ignition engine. The engine 14
includes a crankshaft (not shown) operatively coupled to the input shaft 12 of
the transmission 10. A rotational speed sensor 11 is preferably present to
monitor rotational speed of the input shaft 12. Power output from the engine
14, comprising rotational speed and output torque, can differ from the input


speed, N1, and the input torque, T1, to the transmission 10 due to torque-
consuming components being present on or in operative mechanical contact
with the input shaft 12 between the engine 14 and the transmission 10, e.g., a
hydraulic pump (not shown) and/or a torque management device (not shown).
[0016] In one embodiment the exemplary transmission 10 comprises three
planetary-gear sets 24, 26 and 28, and four selectively-engageable torque-
transmitting devices, i.e., clutches C1 70, C2 62, C3 73, and C4 75. As used
herein, clutches refer to any type of friction torque transfer device including
single or compound plate clutches or packs, band clutches, and brakes, for
example. A hydraulic control circuit 42, preferably controlled by a
transmission control module (hereafter TCM') 17, is operative to control
clutch states. In one embodiment, clutches C2 62 and C4 75 preferably
comprise hydraulically-applied rotating friction clutches. In one embodiment,
clutches C1 70 and C3 73 preferably comprise hydraulically-controlled
stationary devices that can be selectively grounded to a transmission case 68.
In a preferred embodiment, each of the clutches C1 70, C2 62, C3 73, and C4
75 is preferably hydraulically applied, selectively receiving pressurized
hydraulic fluid via the hydraulic control circuit 42.
[0017] In one embodiment, the first and second electric machines 56 and 72
preferably comprise three-phase AC machines, each including a stator (not
shown) and a rotor (not shown), and respective resolvers 80 and 82. The
motor stator for each machine is grounded to an outer portion of the
transmission case 68, and includes a stator core with electrical windings
extending therefrom. The rotor for the first electric machine 56 is supported
on a hub plate gear that is operatively attached to shaft 60 via the second


planetary gear set 26. The rotor for the second electric machine 72 is fixedly
attached to a sleeve shaft hub 66.
[0018] Each of the resolvers 80 and 82 preferably comprises a variable
reluctance device including a resolver stator (not shown) and a resolver rotor
(not shown). The resolvers 80 and 82 are appropriately positioned and
assembled on respective ones of the first and second electric machines 56 and
72. Stators of respective ones of the resolvers 80 and 82 are operatively
connected to one of the stators for the first and second electric machines 56
and 72. The resolver rotors are operatively connected to the rotor for the
corresponding first and second electric machines 56 and 72. Each of the
resolvers 80 and 82 is signally and operatively connected to a transmission
power inverter control module (hereafter 'TPIM') 19, and each senses and
monitors rotational position of the resolver rotor relative to the resolver stator,
thus monitoring rotational position of respective ones of first and second
electric machines 56 and 72. Additionally, the signals output from the
resolvers 80 and 82 are interpreted to provide the rotational speeds for first
and second electric machines 56 and 72, i.e., NA and NB, respectively.
[0019] The transmission 10 includes an output member 64, e.g. a shaft,
which is operably connected to a driveline 90 for a vehicle (not shown), to
provide output power, e.g., to vehicle wheels 93, one of which is shown in
FIG. 1. The output power is characterized in terms of an output rotational
speed, NO and an output torque, TO. A transmission output speed sensor 84
monitors rotational speed and rotational direction of the output member 64.
Each of the vehicle wheels 93, is preferably equipped with a sensor 94 adapted
to monitor wheel speed, the output of which is monitored by a control module


of a distributed control module system described with respect to FIG. 2, to
determine vehicle speed, and absolute and relative wheel speeds for braking
control, traction control, and vehicle acceleration management.
[0020] The input torques from the engine 14 and the first and second electric
machines 56 and 72 (T1, TA, and TB respectively) are generated as a result of
energy conversion from fuel or electrical potential stored in an electrical
energy storage device (hereafter 'ESD') 74. ESD 74 is high voltage DC-
coupled to the TPIM 19 via DC transfer conductors 27. The transfer
conductors 27 include a contactor switch 38. When the contactor switch 38 is
closed, under normal operation, electric current can flow between the ESD 74
and the TPIM 19. When the contactor switch 38 is opened electric current
flow between the ESD 74 and the TPIM 19 is interrupted. The TPIM 19
transmits electrical power to and from the first electric machine 56 by transfer
conductors 29, and the TPIM 19 similarly transmits electrical power to and
from the second electric machine 72 by transfer conductors 31, in response to
torque commands for the first and second electric machines 56 and 72 to
achieve the input torques TA and TB. Electrical current is transmitted to and
from the ESD 74 in accordance with commands provided to the TPIM which
derive from such factors as including operator torque requests, current
operating conditions and states, and such commands determine whether the
ESD 74 is being charged, discharged or is in stasis at any given instant.
[0021] The TPIM 19 includes the pair of power inverters (not shown) and
respective motor control modules (not shown) configured to receive the torque
commands and control inverter states therefrom for providing motor drive or
regeneration functionality to achieve the input torques TA and TB. The power


inverters comprise known complementary three-phase power electronics
devices, and each includes a plurality of insulated gate bipolar transistors (not
shown) for converting DC power from the ESD 74 to AC power for powering
respective ones of the first and second electric machines 56 and 72, by
switching at high frequencies. The insulated gate bipolar transistors form a
switch mode power supply configured to receive control commands. There is
typically one pair of insulated gate bipolar transistors for each phase of each of
the three-phase electric machines. States of the insulated gate bipolar
transistors are controlled to provide motor drive mechanical power generation
or electric power regeneration functionality. The three-phase inverters receive
or supply DC electric power via DC transfer conductors 27 and transform it to
or from three-phase AC power, which is conducted to or from the first and
second electric machines 56 and 72 for operation as motors or generators via
transfer conductors 29 and 31, depending on commands received which are
typically based on factors which include current operating state and operator
torque demand.
[0022] FIG. 2 is a schematic block diagram of the distributed control module
system. The elements described hereinafter comprise a subset of an overall
vehicle control architecture, and provide coordinated system control of the
exemplary hybrid powertrain described in FIG. 1. The distributed control
module system synthesizes pertinent information and inputs, and executes
algorithms to control various actuators to achieve control objectives, including
objectives related to fuel economy, emissions, performance, drivability, and
protection of hardware, including batteries of ESD 74 and the first and second
electric machines 56 and 72. The distributed control module system includes


an engine control module (hereafter 'ECM') 23, the TCM 17, a battery pack
control module (hereafter 'BPCM') 21, and the TPIM 19. A hybrid control
module (hereafter 'HCP') 5 provides supervisory control and coordination of
the ECM 23, the TCM 17, the BPCM 21, and the TPIM 19. A user interface
('UP) 13 is operatively connected to a plurality of devices through which a
vehicle operator may selectively control or direct operation of the electro-
mechanical hybrid powertrain. The devices present in UI 13 typically include
an accelerator pedal 113 ('AP') from which an operator torque request is
determined, an operator brake pedal 112 ('BP'), a transmission gear selector
114 ('PRNDL'), and a vehicle speed cruise control (not shown). The
transmission gear selector 114 may have a discrete number of operator-
selectable positions, including the rotational direction of the output member 64
to enable one of a forward and a reverse direction.
[0023] The aforementioned control modules communicate with other control
modules, sensors, and actuators via a local area network (hereafter 'LAN') bus
6. The LAN bus 6 allows for structured communication of states of operating
parameters and actuator command signals between the various control
modules. The specific communication protocol utilized is application-specific.
The LAN bus 6 and appropriate protocols provide for robust messaging and
multi-control module interfacing between the aforementioned control
modules, and other control modules providing functionality such as antilock
braking, traction control, and vehicle stability. Multiple communications
buses may be used to improve communications speed and provide some level
of signal redundancy and integrity. Communication between individual

control modules can also be effected using a direct link, e.g., a serial
peripheral interface ('SPF) bus (not shown).
[0024] The HCP 5 provides supervisory control of the powertrain, serving to
coordinate operation of the ECM 23, TCM 17, TPIM 19, and BPCM 21.
Based upon various input signals from the user interface 13 and the
powertrain, including the ESD 74, the HCP 5 generates various commands,
including: the operator torque request (To REQ'), a commanded output torque
('TCMD') to the driveline 90, an engine input torque command, clutch torques
for the torque-transfer clutches C1 70, C2 62, C3 73, C4 75 of the
transmission 10; and the torque commands for the first and second electric
machines 56 and 72, respectively. The TCM 17 is operatively connected to the
hydraulic control circuit 42 and provides various functions including
monitoring various pressure sensing devices (not shown) and generating and
communicating control signals to various solenoids (not shown) thereby
controlling pressure switches and control valves contained within the
hydraulic control circuit 42.
[0025] The ECM 23 is operatively connected to the engine 14, and functions
to acquire data from sensors and control actuators of the engine 14 over a
plurality of discrete lines, shown for simplicity as an aggregate bi-directional
interface cable 35. The ECM 23 receives the engine input torque command
from the HCP 5. The ECM 23 determines the actual engine input torque, T|,
provided to the transmission 10 at that point in time based upon monitored
engine speed and load, which is communicated to the HCP 5. The ECM 23
monitors input from the rotational speed sensor 11 to determine the engine
input speed to the input shaft 12, which translates to the transmission input


speed, N1. The ECM 23 monitors inputs from sensors (not shown) to
determine states of other engine operating parameters which may include
without limitation: a manifold pressure, engine coolant temperature, throttle
position, ambient air temperature, and ambient pressure. The engine load can
be determined, for example, from the manifold pressure, or alternatively, from
monitoring operator input to the accelerator pedal 113. The ECM 23
generates and communicates command signals to control engine actuators,
which may include without limitation actuators such as: fuel injectors, ignition
modules, and throttle control modules, none of which are shown.
[0026] The TCM 17 is operatively connected to the transmission 10 and
monitors inputs from sensors (not shown) to determine states of transmission
operating parameters. The TCM 17 generates and communicates command
signals to control the transmission 10, including controlling the hydraulic
circuit 42. Inputs from the TCM 17 to the HCP 5 include estimated clutch
torques for each of the clutches, i.e., C1 70, C2 62, C3 73, and C4 75, and
rotational output speed, NO, of the output member 64. Other actuators and
sensors may be used to provide additional information from the TCM 17 to the
HCP 5 for control purposes. The TCM 17 monitors inputs from pressure
switches (not shown) and selectively actuates pressure control solenoids (not
shown) and shift solenoids (not shown) of the hydraulic circuit 42 to
selectively actuate the various clutches C1 70, C2 62, C3 73, and C4 75 to
achieve various transmission operating range states, as described hereinbelow.
[0027] The BPCM 21 is signally connected to sensors (not shown) to
monitor the ESD 74, including states of electrical current and voltage
parameters, to provide information indicative of parametric states of the


batteries of the ESD 74 to the HCP 5. The parametric states of the batteries
preferably include battery state-of-charge, battery voltage, battery temperature,
and available battery power, referred to as a range PBAT_MIN to PBAT MAX.
[0028] Each of the control modules ECM 23, TCM 17, TPIM 19 and BPCM
21 is preferably a general-purpose digital computer comprising a
microprocessor or central processing unit, storage mediums comprising read
only memory ('ROM'), random access memory ('RAM'), electrically
programmable read only memory ('EPROM'), a high speed clock, analog to
digital ('A/D') and digital to analog ('D/A') circuitry, and input/output
circuitry and devices ('I/O') and appropriate signal conditioning and buffer
circuitry. Each of the control modules has a set of control algorithms,
comprising resident program instructions and calibrations stored in one of the
storage mediums and executed to provide the respective functions of each
computer. Information transfer between the control modules is preferably
accomplished using the LAN bus 6 and serial peripheral interface buses. The
control algorithms are executed during preset loop cycles such that each
algorithm is executed at least once each loop cycle. Algorithms stored in the
non-volatile memory devices are executed by one of the central processing
units to monitor inputs from the sensing devices and execute control and
diagnostic routines to control operation of the actuators, using preset
calibrations. Loop cycles are preferably executed at regular intervals, for
example at each 3.125, 6.25,12.5,25 and 100 milliseconds during ongoing
operation of the powertrain. However, any interval between about 2
milliseconds and about 300 milliseconds may be selected. Alternatively,

algorithms may be executed in response to the occurrence of any selected
event.
[0029] The exemplary powertrain shown in reference to FIG. 1 is capable of
selectively operating in any of several operating range states that can be
described in terms of an engine state comprising one of an engine on state
('ON') and an engine off state ('OFF'), and a transmission state comprising a
plurality of fixed gears and continuously variable operating modes, described
with reference to Table 1, below.

[0030] Each of the transmission operating range states is described in the
table and indicates which of the specific clutches C1 70, C2 62, C3 73, and C4
75 are applied for each of the operating range states. As an example, a first
continuously variable mode, i.e., EVT Mode 1, or Ml, is selected by applying
clutch C1 70 only in order to "ground" the outer gear member of the third
planetary gear set 28. The engine state can be one of ON ('Ml_Eng_On') or
OFF ('Ml_Eng_Off). A second continuously variable mode, i.e., EVT Mode

2, or M2, is selected by applying clutch C2 62 only to connect the shaft 60 to
the carrier of the third planetary gear set 28. The engine state can be one of
ON ('M2_Eng_On') or OFF ('M2_Eng_Off). For purposes of this
description, when the engine state is OFF, the engine input speed is equal to
zero revolutions per minute ('RPM'), i.e., the engine crankshaft is not rotating.
A fixed gear operation provides a fixed ratio operation of input-to-output
speed of the transmission 10, i.e., N1/NO, is achieved. For example, a first
fixed gear operation ('Gl') is selected by applying clutches C1 70 and C4 75.
A second fixed gear operation ('G2') is selected by applying clutches C1 70
and C2 62. A third fixed gear operation ('G3') is selected by applying
clutches C2 62 and C4 75. A fourth fixed gear operation ('G4') is selected by
applying clutches C2 62 and C3 73. The fixed ratio operation of input-to-
output speed increases with increased fixed gear operation due to decreased
gear ratios in the planetary gears 24,26, and 28. The rotational speeds of the
first and second electric machines 56 and 72, NA and NB respectively, are
dependent on internal rotation of the mechanism as defined by the clutching
and are proportional to the input speed measured at the input shaft 12.
[0031] In response to operator input via the accelerator pedal 113 and brake
pedal 112 as captured by the user interface 13, the HCP 5 and one or more of
the other control modules determine torque commands to control the torque
generative devices comprising the engine 14 and the first and second electric
machines 56 and 72 to meet the operator torque request at the output member
64 and transferred to the driveline 90. Based upon input signals from the user
interface 13 and the hybrid powertrain including the ESD 74, the HCP 5
determines the operator torque request, a commanded output torque from the


transmission 10 to the driveline 90, the input torque from the engine 14, clutch
torques for the torque-transfer clutches C1 70, C2 62, C3 73, C4 75 of the
transmission 10; and the motor torques for the first and second electric
machines 56 and 72, respectively, as is described hereinbelow.
[0032] Final vehicle acceleration can be affected by other factors including,
e.g., road load, road grade, and vehicle mass. The engine state and the
transmission operating range state are determined based upon operating
characteristics of the hybrid powertrain. This includes the operator torque
request communicated through the accelerator pedal 113 and brake pedal 112
to the user interface 13 as previously described. The transmission operating
range state and the engine state may be predicated on a hybrid powertrain
torque demand caused by a command to operate the first and second electric
machines 56 and 72 in an electrical energy generating mode or in a torque
generating mode. The transmission operating range state and the engine state
can be determined by an optimization algorithm or routine which determines
optimum system efficiency based upon operator demand for power, battery
state of charge, and energy efficiencies of the engine 14 and the first and
second electric machines 56 and 72. The control system manages torque
inputs from the engine 14 and the first and second electric machines 56 and 72
based upon an outcome of the executed optimization routine, and system
efficiencies are optimized thereby, to manage fuel economy and battery
charging. Furthermore, operation can be determined based upon a fault in a
component or system. The HCP 5 monitors the torque-generative devices, and
determines the power output from the transmission 10 at output member 64
that is required to meet the operator torque request while meeting other


powertrain operating demands, e.g., charging the ESD 74. As should be
apparent from the description above, the ESD 74 and the first and second
electric machines 56 and 72 are electrically-operatively coupled for power
flow therebetween. Furthermore, the engine 14, the first and second electric
machines 56 and 72, and the electro-mechanical transmission 10 are
mechanically-operatively coupled to transfer power therebetween to generate a
power flow to the output member 64.
[0033] FIG. 3 shows a control system architecture for controlling and
managing signal flow in a hybrid powertrain system having multiple torque
generative devices, described hereinbelow with reference to the hybrid
powertrain system of FIGS. 1 and 2, and residing in the aforementioned
control modules in the form of executable algorithms and calibrations. The
control system architecture is applicable to alternative hybrid powertrain
systems having multiple torque generative devices, including, e.g., a hybrid
powertrain system having an engine and a single electric machine, a hybrid
powertrain system having an engine and multiple electric machines.
Alternatively, the hybrid powertrain system can utilize non-electric torque-
generative machines and energy storage systems, e.g., hydraulic-mechanical
hybrid transmissions (not shown).
[0034] In operation, the operator inputs to the accelerator pedal 113 and the
brake pedal 112 are monitored to determine the operator torque request. The
operator inputs to the accelerator pedal 113 and the brake pedal 112 comprise
individually determinable operator torque request inputs including an
immediate accelerator output torque request ('Output Torque Request Accel
Immed'), a predicted accelerator output torque request ('Output Torque


Request Accel Prdtd'), an immediate brake output torque request ('Output
Torque Request Brake Immed'), a predicted brake output torque request
('Output Torque Request Brake Prdtd') and an axle torque response type
('Axle Torque Response Type'). As used herein, the term 'accelerator' refers
to an operator request for forward propulsion preferably resulting in increasing
vehicle speed over the present vehicle speed, when the operator selected
position of the transmission gear selector 114 commands operation of the
vehicle in the forward direction. The terms 'deceleration' and 'brake' refer to
an operator request preferably resulting in decreasing vehicle speed from the
present vehicle speed. The immediate accelerator output torque request, the
predicted accelerator output torque request, the immediate brake output torque
request, the predicted brake output torque request, and the axle torque
response type are individual inputs to the control system. Additionally,
operation of the engine 14 and the transmission 10 are monitored to determine
the input speed ('Ni') and the output speed ('No'). The immediate accelerator
output torque request is determined based upon a presently occurring operator
input to the accelerator pedal 113, and comprises a request to generate an
immediate output torque at the output member 64 preferably to accelerate the
vehicle. The predicted accelerator output torque request is determined based
upon the operator input to the accelerator pedal 113 and comprises an
optimum or preferred output torque at the output member 64. The predicted
accelerator output torque request is preferably equal to the immediate
accelerator output torque request during normal operating conditions, e.g.,
when any one of antilock braking, traction control, or vehicle stability is not
being commanded. When any one of antilock braking, traction control or


vehicle stability is being commanded the predicted accelerator output torque
request remains the preferred output torque with the immediate accelerator
output torque request being decreased in response to output torque commands
related to the antilock braking, traction control, or vehicle stability control.
[0035] The immediate brake output torque request is determined based upon
a presently occurring operator input to the brake pedal 112, and comprises a
request to generate an immediate output torque at the output member 64 to
effect a reactive torque with the driveline 90 which preferably decelerates the
vehicle. The predicted brake output torque request comprises an optimum or
preferred brake output torque at the output member 64 in response to an
operator input to the brake pedal 112 subject to a maximum brake output
torque generated at the output member 64 allowable regardless of the operator
input to the brake pedal 112. In one embodiment the maximum brake output
torque generated at the output member 64 is limited to -0.2g. The predicted
brake output torque request can be phased out to zero when vehicle speed
approaches zero regardless of the operator input to the brake pedal 112. When
commanded by the operator, there can be operating conditions under which
the predicted brake output torque request is set to zero, e.g., when the operator
setting to the transmission gear selector 114 is set to a reverse gear, and when
a transfer case (not shown) is set to a four-wheel drive low range.
[0036] A strategic control scheme ('Strategic Control') 310 determines a
preferred input speed ('Ni_Des') and a preferred engine state and transmission
operating range state ('Hybrid Range State Des') based upon the output speed
and the operator torque request and based upon other operating parameters of
the hybrid powertrain, including battery power limits and response limits of


the engine 14, the transmission 10, and the first and second electric machines
56 and 72. The predicted accelerator output torque request and the predicted
brake output torque request are input to the strategic control scheme 310. The
strategic control scheme 310 is preferably executed by the HCP 5 during each
100 ms loop cycle and each 25 ms loop cycle. The desired operating range
state for the transmission 10 and the desired input speed from the engine 14 to
the transmission 10 are inputs to the shift execution and engine start/stop
control scheme 320.
[0037] The shift execution and engine start/stop control scheme 320
commands changes in the transmission operation ('Transmission Commands')
including changing the operating range state based upon the inputs and
operation of the powertrain system. This includes commanding execution of a
change in the transmission operating range state if the preferred operating
range state is different from the present operating range state by commanding
changes in application of one or more of the clutches C1 70, C2 62, C3 73,
and C4 75 and other transmission commands. The present operating range
state ('Hybrid Range State Actual') and an input speed profile ('NiProf) can
be determined. The input speed profile is an estimate of an upcoming input
speed and preferably comprises a scalar parametric value that is a targeted
input speed for the forthcoming loop cycle. The engine operating commands
and the operator torque request are based upon the input speed profile during a
transition in the operating range state of the transmission.
[0038] A tactical control scheme ('Tactical Control and Operation') 330 is
executed during one of the control loop cycles to determine engine commands
('Engine Commands') for operating the engine 14, including a preferred input


torque from the engine 14 to the transmission 10 based upon the output speed,
the input speed, and the operator torque request comprising the immediate
accelerator output torque request, the predicted accelerator output torque
request, the immediate brake output torque request, the predicted brake output
torque request, the axle torque response type, and the present operating range
state for the transmission. The engine commands also include engine states
including one of an all-cylinder operating state and a cylinder deactivation
operating state wherein a portion of the engine cylinders are deactivated and
unfueled, and engine states including one of a fueled state and a fuel cutoff
state. An engine command comprising the preferred input torque of the
engine 14 and the present input torque (Ti') reacting between the engine 14
and the input member 12 are preferably determined in the ECM 23. Clutch
torques ('Tel') for each of the clutches C1 70, C2 62, C3 73, and C4 75,
including the presently applied clutches and the non-applied clutches are
estimated, preferably in the TCM 17.
[0039] An output and motor torque determination scheme ('Output and
Motor Torque Determination') 340 is executed to determine the preferred
output torque from the powertrain ('Tocmd'). This includes determining
motor torque commands ('TA', 'TB') to transfer a net commanded output
torque to the output member 64 of the transmission 10 that meets the operator
torque request, by controlling the first and second electric machines 56 and 72
in this embodiment. The immediate accelerator output torque request, the
immediate brake output torque request, the present input torque from the
engine 14 and the estimated applied clutch torque(s), the present operating
range state of the transmission 10, the input speed, the input speed profile, and


the axle torque response type are inputs. The output and motor torque
determination scheme 340 executes to determine the motor torque commands
during each iteration of one of the loop cycles. The output and motor torque
determination scheme 340 includes algorithmic code which is regularly
executed during the 6.25 ms and 12.5 ms loop cycles to determine the
preferred motor torque commands.
[0040] The hybrid powertrain is controlled to transfer the output torque to
the output member 64 to react with the driveline 90 to generate tractive torque
at wheel(s) 93 to forwardly propel the vehicle in response to the operator input
to the accelerator pedal 113 when the operator selected position of the
transmission gear selector 114 commands operation of the vehicle in the
forward direction. Similarly, the hybrid powertrain is controlled to transfer
the output torque to the output member 64 to react with the driveline 90 to
generate tractive torque at wheel(s) 93 to propel the vehicle in a reverse
direction in response to the operator input to the accelerator pedal 113 when
the operator selected position of the transmission gear selector 114 commands
operation of the vehicle in the reverse direction. Preferably, propelling the
vehicle results in vehicle acceleration so long as the output torque is sufficient
to overcome external loads on the vehicle, e.g., due to road grade,
aerodynamic loads, and other loads.
[0041] Fig. 4 details signal flow in the strategic optimization control scheme
310, which includes a strategic manager 220, an operating range state analyzer
260, and a state stabilization and arbitration block 280 to determine the
preferred input speed ('Ni_Des') and the preferred transmission operating
range state ('Hybrid Range State Des'). The strategic manager ('Strategic


Manager') 220 monitors the output speed N0, the predicted accelerator output
torque request ('Output Torque Request Accel Prdtd'), the predicted brake
output torque request ('Output Torque Request Brake Prdtd'), and available
battery power PBAT_MIN to PBAT_MAX. The strategic manager 220 determines
which of the transmission operating range states are allowable, and determines
output torque requests comprising a strategic accelerator output torque request
('Output Torque Request Accel Strategic') and a strategic net output torque
request ('Output Torque Request Net Strategic'), all of which are input the
operating range state analyzer 260 along with system inputs ('System Inputs'),
power cost inputs ('Power Cost Inputs'), and any associated penalty costs
('Penalty Costs') for operating outside of predetermined limits. The operating
range state analyzer 260 generates a preferred power cost ('P*cost') and
associated input speed ('NT) for each of the allowable operating range states
based upon the operator torque requests, the system inputs, the available
battery power and the power cost inputs. The preferred power costs and
associated input speeds for the allowable operating range states are input to the
state stabilization and arbitration block 280 which selects the preferred
operating range state and preferred input speed based thereon.
[0042] Fig. 5 shows the operating range state analyzer 260 that executes
searches in each candidate operating range state comprising the allowable ones
of the operating range states, including Ml (262), M2 (264), Gl (270), G2
(272), G3 (274), and G4 (276) to determine preferred operation of the torque
actuators, i.e., the engine 14 and the first and second electric machines 56 and
72 in this embodiment. The preferred operation preferably comprises a
minimum power cost for operating the hybrid powertrain system and an


associated engine input for operating in the candidate operating range state in
response to the operator torque request. The associated engine input
comprises at least one of a preferred engine input speed ('NI'), a preferred
engine input power ('PI'), and a preferred engine input torque (TI') that is
responsive to and preferably meets the operator torque request. The operating
range state analyzer 260 evaluates powertrain operation in Ml-Engine Off
(264) and M2-Engine Off (266) states to determine a preferred cost ('P*cost')
for operating the powertrain system responsive to and preferably meeting the
operator torque request when the engine 14 is in the engine-off state.
[0043] Fig. 6 schematically shows signal flow for a 1 -dimension search
scheme 610, executed in each of Gl (270), G2 (272), G3 (274), and G4 (276).
A range of one controllable input, in this embodiment comprising minimum
and maximum input torques ('TiMin/Max'), is input to a 1-D search engine
415. The 1-D search engine 415 iteratively generates candidate input torques
('Ti(j)') which range between the minimum and maximum input torques, each
which is input to an optimization function ('Opt To/Ta/Tb') 440, for n search
iterations. Other inputs to the optimization function 440 include system inputs
preferably comprise parametric states for battery power, clutch torques,
electric motor operation, transmission and engine operation, the specific
operating range state and the operator torque request. The optimization
function 440 determines transmission operation comprising an output torque,
motor torques, and associated battery and electrical powers ('To(j), Ta(j),
Tb(j), Pbat(j), Pa(j), Pb(j)') associated with the candidate input torque based
upon the system inputs in response to the operator torque request for the
candidate operating range state. The output torque, motor torques, and


associated battery powers, penalty costs, and power cost inputs are input to a
cost function 450, which executes to determine a power cost ('Pcost(j)') for
operating the powertrain in the candidate operating range state at the candidate
input torque in response to the operator torque request. The 1 -D search engine
415 iteratively generates candidate input torques over the range of input
torques. The optimization function 440 determines the transmission operation
for each candidate input torque. The cost function 450 determines the
associated power costs. The The 1-D search engine 415 identifies a preferred
input torque ('TI') and associated preferred cost ('P*cost'). The preferred
input torque ('TI') comprises the candidate input torque within the range of
input torques that results in a minimum power cost of the candidate operating
range state, i.e., the preferred cost.
[0044] The preferred operation in each of Ml and M2 can be determined by
executing a 2-dimensional search scheme 620, shown with reference to Figs. 7
and 8, in conjunction with executing a 1-dimensional search using the 1-
dimensional search scheme 610 based upon a previously determined input
speed which can be arbitrated ('Input Speed Stabilization and Arbitration')
615 to determine preferred input speeds ('N*i') and associated preferred costs
('P*cost') for the operating range states.
[0045] Fig. 7 shows the preferred operation in each of continuously variable
modes Ml and M2 executed in blocks 262 and 264 of the operating range state
analyzer 260. This includes executing a 2-dimensional search scheme 620,
shown with reference to Figs. 6 and 8, in conjunction with executing a 1 -
dimensional search using the 1-dimensional search scheme 610 based upon a
previously determined input speed which can be arbitrated ('Input Speed


Stabilization and Arbitration') 615 to determine preferred costs ('P*cost') and
associated preferred input speeds ('NT) for the operating range states. As
described with reference to Fig. 8, the 2-dimensional search scheme 620
determines a a first preferred cost ('2D P*cost') and an associated first
preferred input speed ('2D NT). The first preferred input speed is input to
the 2-dimensional search scheme 620 and to an adder 612. The adder 612
sums the first preferred input speed and a time-rate change in the input speed
('NI_DOT') multiplied by a predetermined time period ('dt'). The resultant is
input to a switch 605 along with the first preferred input speed determined by
the 2-dimensional search scheme 620. The switch 605 is controlled to input
either the resultant from the adder 612 or the preferred input speed determined
by the 2-dimensional search scheme 620 into the 1-dimensional search scheme
610. The switch 605 is controlled to input the preferred input speed
determined by the 2-dimensional search scheme 620 into the 1 -dimensional
search scheme 610 (as shown) when the powertrain system is operating in a
regenerative braking mode, e.g., when the operator torque request includes a
request to generate an immediate output torque at the output member 64 to
effect a reactive torque with the driveline 90 which preferably decelerates the
vehicle. The switch 605 is controlled to a second position (not shown) to
input the resultant from the adder 612 when the operator torque request does
not include regenerative braking. The 1-dimensional search scheme 610 is
executed to determine a second preferred cost (' 1D P*cost') using the 1 -
dimensional search scheme 610, which is input to the input speed stabilization
and arbitration block 615 to select a final preferred cost and associated
preferred input speed.


[0046] Fig. 8 schematically shows signal flow for the 2-dimension search
scheme 620. Ranges of two controllable inputs, in this embodiment
comprising minimum and maximum input speeds ('Ni Min/Max') and
minimum and maximum input powers ('Pi Min/Max') are input to a 2-D
search engine 410. In another embodiment, the two controllable inputs can
comprise minimum and maximum input speeds and minimum and maximum
input torques. The 2-D search engine 410 iteratively generates candidate
input speeds ('Ni(j)') and candidate input powers ('Pi(j)') which range
between the minimum and maximum input speeds and powers. The candidate
input power is preferably converted to a candidate input torque ('Ti(j)') (412).
Each candidate input speed ('Ni(j)') and candidate input torque ('Ti(j)') are
input to the optimization function ('Opt To/Ta/Tb') 440, for n search
iterations. Other inputs to the optimization function 440 include system inputs
preferably comprising parametric states for battery power, clutch reactive
torques, maximum and minimum torque outputs from the first and second
electric machines 56 and 72, engine input torque, the specific operating range
state and the operator torque request. The optimization function 440
determines transmission operation comprising an output torque, motor torques,
and associated battery and electrical powers ('To(j), Ta(j), Tb(j), Pbat(j), Pa(j),
Pb(j)') associated with the candidate input power and candidate input speed
based upon the system inputs and the operating torque request for the
candidate operating range state. The output torque, motor torques, and
associated battery powers, penalty costs and power cost inputs are input to a
cost function 450, which executes to determine a power cost ('Pcost(j)') for
operating the powertrain at the candidate input power and candidate input


speed in response to the operator torque request in the candidate operating
range state. The 2-D search engine 410 iteratively generates the candidate
input speeds and candidate input powers over the range of input speeds and
range of input powers. The optimization function 440 determines the
transmission operation for each candidate input speed and candidate input
power. The cost function 450 determines the associated power costs. The 2-D
search engine 410 identifies a preferred input power ('PI') and preferred
input speed ('NI') and associated preferred cost ('P*cost'). The preferred
input power ('PI') and preferred input speed ('NI') comprises the candidate
input power and candidate input speed that result in a minimum power cost for
the candidate operating range state.
[0047] Fig. 9 schematically shows power flow and power losses through
hybrid powertrain system, in context of the exemplary powertrain system
described above. There is a first power flow path from a fuel storage system 9
which transfers fuel power ('PFUEL') to the engine 14 which transfers input
power ('Pi') to the transmission 10. The power loss in the first flow path
comprises engine power losses ('PLOSS ENG')- There is a second power flow
path which transfers electric power ('PBAT') from the ESD 74 to the TPIM 19
which transfers electric power ('PINVELEC') to the first and second electric
machines 56 and 72 which transfer motor mechanical power ('PMOTOR MECH ')
to the transmission 10. The power losses in the second power flow path
include battery power losses ('PLOSS BATT') and electric motor power losses
('PLOSS MOTOR')- The TPIM 19 has an electric power load ('PHV LOAD') that
services electric loads in the system ('HV Loads'), which can include a low
voltage battery storage system (not shown). The transmission 10 has a


mechanical inertia power input ('PINERTIA') in the system ('Inertia Storage')
that preferably include inertias from the engine 14 and the transmission 10.
The transmission 10 has mechanical power losses ('PLOSS MECH') and power
output ('POUT')- The brake system 94 has brake power losses ('PLOSS BRAKE')
and the remaining power is transferred to the driveline as axle power
('PAXLE').
[0048] The power cost inputs to the cost function 450 are determined based
upon factors related to vehicle driveability, fuel economy, emissions, and
battery usage. Power costs are assigned and associated with fuel and
electrical power consumption and are associated with a specific operating
points of the hybrid powertrain. Lower operating costs can be associated with
lower fuel consumption at high conversion efficiencies, lower battery power
usage, and lower emissions for each engine speed/load operating point, and
take into account the candidate operating state of the engine 14. As described
hereinabove, the power costs may include the engine power losses ('PLOSS
ENG'), electric motor power losses ('PLOSS MOTOR'), battery power losses ('PLOSS
BATT'), brake power losses ('PLOSS BRAKE'), and mechanical power losses
('PLOSS MECH') associated with operating the hybrid powertrain at a specific
operating point which includes input speed, motor speeds, input torque, motor
torques, a transmission operating range state and an engine state.
[0049] The mechanical power loss in the transmission 10 includes power
losses due to rotational spinning, torque transfer, and friction, and operation of
parasitic loads, e.g., a hydraulic pump (not shown) for the transmission 10.
The mechanical power loss can be determined for each operating range state

for the transmission 14 and input speed. Mechanical power loss related to the
input speed ('Ni') and the output speed ('No') can be represented by Eq. 1:
PMECHLOSS=aN1+bN12+cN1N0+dN20 [1]
wherein a, b, c, and d comprise calibrated scalar values determined for the
specific powertrain system and each specific transmission operating range
state.
[0050] Thus, in fixed gear operation, i.e., in one of the fixed gear operating
ranges states of Gl, G2, G3 and G4 for the embodiment described herein, the
power cost input comprising the mechanical power loss to the cost function
450 can be predetermined outside of the 1-dimension search scheme 610. In
mode operation, i.e., in one of the mode operating ranges states of Ml and M2
for the embodiment described herein, the power cost input comprising the
mechanical power loss to the cost function 450 can be determined during each
iteration of the search scheme 620.
[0051] The state stabilization and arbitration block 280 selects a preferred
transmission operating range state ('Hybrid Range State Des') which
preferably is the transmission operating range state associated with the
minimum preferred cost for the allowed operating range states output from the
operating range state analyzer 260, taking into account factors related to
arbitrating effects of changing the operating range state on the operation of the
transmission to effect stable powertrain operation. The preferred input speed
('Ni_Des') is the engine input speed associated with the preferred engine input
comprising the preferred engine input speed ('NI'), the preferred engine input


power ('PI'), and the preferred engine input torque ('TI') that is responsive
to and preferably meets the operator torque request for the selected preferred
transmission operating range state. Due to subjective constraints imposed on
a system such as that herein described, the transmission operating range state
selected may not in all cases be that which is truly optimal from the standpoint
of energy usage and power losses.
[0052] In one embodiment, such a system may provide a search method for
determining a desirable input speed for a transmission in a combination that
comprises at least one torque actuator mechanically coupled to the
transmission, the torque actuator contributing to the input speed of said
transmission. One search method includes first selecting a potential operating
point for the at least one torque actuator from a search range, in which the
potential operating point has associated with it a transmission input speed
value and a transmission input power value. For purposes of the disclosure,
the term 'candidate' can be used interchangeably with the term 'potential' in
describing operating points and transmission operating range states. A
plurality of power losses associated with operation of the combination at the
potential operating point is determined, each which is combined to provide a
total power loss for that point. The selection of a potential operating point,
determination of power losses and their combination is repeated to provide a
plurality of potential operating points, each of which have a total power loss
associated with them. The potential operating points are evaluated for
desirability, based on at least one criteria selected from the group consisting
of: objective operating criteria and subjective operating criteria, and one
operating point is selected from the plurality of potential operating points.


Conducting such a search method under the constraint that the output power of
said transmission is kept substantially-constant provides that the contours of
the power losses (costs) are more prone to be linear when defined in an N1, P1
plane, thus providing advantageous rapidity for a search engine that
incorporates such methodology to convergence on an operating point of
interest.
[0053] A search engine such as 410 can be conceived of as operating on a
defined two-dimensional space that contains points corresponding to candidate
Ni and PI values for each potential transmission operating range state, such as
space S as shown in FIG. 10 as the region on the coordinate axes bounded by
Pi Min, PI Max, N1 Min, and N1 Max, wherein P1represents input power to the
electro-mechanical hybrid transmission and N1 is the transmission input speed.
The space S, which is the search range, is defined using hardware
specifications, which typically include electric machine operating speed limits,
engine operating speed limits, transmission output speed, and engine torque
limits. However, in general, the space S is not disposed at a static location on
the P1 , N1 coordinate axes, but rather changes its position over time in response
to operating conditions, which may include changes in operator torque
requests and changes in road grade. Changes in the location of the space S on
the P1 , N1 coordinate axes can occur at every iteration of an operational loop in
a microprocessor carrying out the iterations and can occur at intervals as short
as 1 millisecond. Thus, over a few seconds time, the space S may effectively
sweep out a very large space over potential values within the P1 , N1 coordinate
axes. In accordance with one embodiment of the disclosure, a reduction the
effective size of the space S is effected.


[0054] In one embodiment a search engine such as search engine 410
selects, either randomly or according to any desired algorithm, an N1 and P1
pair present in the space S, and a maximum transmission output torque (To
Max) and a minimum transmission output torque (To Min) associated with the
N1 and P1pair chosen is calculated based on system constraints. Repetition of
this method for a large number of different potential N1 and P1pairs provides a
plurality of different To Min and To Max values for each potential
transmission operating range state. The method is repeated for each potential
transmission operating range state and a plurality of To Min and To Max pairs
are generated for the space S of and for each potential transmission operating
range state and NI and P[ pairs provided.
[0055] From such plurality of different To Min and To Max values so
generated by a search engine for a given potential transmission operating
range state, the NI and PI pair having the highest To Max value associated with
each potential transmission operating range state is generally selected as the
preferred NI and PI pair when an operator torque request is greater than To
Max. In some embodiments for cases in which an operator torque request is
less than To Min, the potential NI and PI pair associated with the lowest To
Min value is generally selected as the preferred NI and PI for the particular
potential transmission operating range state under consideration. In any event,
it is in generally desirable to be able to quickly locate, within a space S for
each potential transmission operating range state, that NI and PI pair that has
the least power losses associated with it. The effectiveness of such a task is
inhibited by the fact that the location of the space S is moving essentially

constantly, which over time makes the effective size of the search range of the
space S very large.
[0056] Towards reduction of the effective size of the space S, pre-
calculations are undertaken in a computer simulation which in one
embodiment is not operatively connected to a drivetrain as described herein.
Such pre-calculations, or off-line simulations, are carried out using values for
engine coolant temperature, engine torque curves, battery power limits,
electric machine speed limits, electric machine torque limits, transmission oil
temperature, and battery state-of-charge which are frequently encountered by a
motorized vehicle during its operation, to determine maximum and minimum
values for NI and PI which can be used to define a space S that is smaller in
range than the space S that is encountered during use of a search engine and
system useful therewith as herein described. Without use of a method as
described herein, the search range embraced by the space S was based on Nj
min and NI max values that were based on speed-based system constraints and
Pi min and PI max values that were based on TI min and TI max values
provided by the ECM 23; however a method as provided herein narrows down
the search range embraced by the space S, based on off-line simulation results.
[0057] In one embodiment of the disclosure the Ni, PI plane representing
search range embraced by the space S is determined by first choosing one
point in that plane and evaluating it for power losses. Other points are chosen,
either arbitrarily or according to any desire algorithm and similarly evaluated
for power loss if the system were operating at those points. By evaluating, via
an off-line computer simulation, a large number of points (which may be on
the order of 100,000 points), a contour plot such as that shown in FIG. 11 is


obtained. The contour lines present in the plot of FIG. 11 represent points
having equal power losses, or costs associated with operating at those points.
The process of generating a plot such as that shown in FIG. 11 is repeated for
points having different combinations of transmission output speeds and
transmission output torques to provide one such plot as shown in FIG. 11 for
each No, To point. By such a method, an off-line "library" of plots is
generated, the number of which plots is determined by the desires of the
programmer, for example, in one embodiment, a library containing about 2500
of such plots is generated.
[0058] Thus, according to the foregoing, the search range was determined by
an off-line simulation that evaluates each point in the Ni, PI plane within the
"large" search range space S set by system constraints. FIG. 11 shows the
total power loss (Cost) at an operating point (No, To) in the Ni, PI domain.
The steep contour changes represent the violation of system constraints, e.g.,
To, Ta, Tb, Ti, and Peatt. The suggested search range space S excludes
operating points that violate system constraints and points associated with
large costs that are (subjectively) determined as non desirable. For To points
that are beyond the deliverable To limits, a torque margin is included in the
window search determination, so that the window does not shrink to a single
point in the search plane.
[0059] From FIG. 11 one can get an idea of locations within the plot where
the energy losses (costs, as expressed in units of power therein) are relatively
small, which is the area labeled B within the highlighted box in FIG. 11. The
space labeled B in FIG. 11 may be determined using an algorithm, one
example of which is shown below:


If To > To Max Max - To Margin
Find Ni, PI Range where (To Max penalty Cost (PBatt Penalty cost Elself To > To MinMin + To Margin
Find Ni, PI Range where (To Min penalty Cost (PBatt Penalty cost Else
Find Ni, PI Range where (To Min a) & ( Tb Penalty Cost End
in which a, b, c, and d are cost criteria that can reduce the search range to
exclude operating points that reside outside of the system constraints. Setting
these values to 0 will exclude all points not within the constraints. Setting the
values to a small, non-zero positive value has the effect of providing a margin
around each of the system constraints to minimize the effect of simulation
errors that could otherwise erroneously exclude points that are within the
constraints. The Ta/Tb/Ti/PBatt penalty costs refer to the costs that are
imposed to the Ni, PI pair that is associated with Ta, Tb, Ti, PBatt points that
are not within their achievable limits. In general, these penalty costs are
provided to increase proportionally with the amount of how much each point
exceeds each achievable limit. The cost criteria "e" can further reduce the
search range to exclude points that are within the system constraints but have
high objective power loss costs subjectively determined as being non-optimal.
In the first If step, a ToMax(ToMin) is calculated for each Ni, PI point that is

evaluated by including the Output Torque limiting inside the search loop.
ToMaxMax (ToMinMin) is the maximum(minimum) of all ToMax(ToMin),
which represents the maximum(minimum) output torque that can be produced
within the evaluated Ni, PI range. In the Else step, the Objective Power Loss
cost is the sum of battery power loss, machine power loss, engine power loss,
and transmission power loss.
[0060] A process as set forth above with respect to determining the area B on
FIG. 11 may be repeated, for each plot that exists in the library that was
generated during the off-line simulation, to arrive at an area for each plot that
is analogous to area B of FIG. 11. In the hypothetical case, such as the one
mentioned above in which a library containing 2500 of such plots is generated,
an area analogous to area B of FIG. 11 is generated for each of the 2500 plots.
However, the area B of FIG. 11 can be represented by the four points which
define the rectangle of area B therein, and in a method according to one
embodiment of the disclosure in which a library containing 2500 of the
aforementioned plots were generated, one outcome is a set of four points for
each of the 2500 plots generated.
[0061] An alternate representation of the four points for each of the 2500
plots so generated per the foregoing, is to provide four tables of data, each of
which four tables of data comprise 2500 entries, and each of which four tables
contain values of NI min, Nj max, PI min, and PI max, as shown in FIG. 12.
Such a table containing NI min values is amplified in the bubble of FIG. 12
and is seen to comprise fifty columns of No values and fifty rows of To
values. It is well known in the art to convert power values to torque values
when the rpm is known. The tables for the NI max, Pj min, and PI max are


similarly structured. Thus, when a vehicle operator makes a power request
having No and To values associated with it such as is shown at the top of FIG.
12, determination of the NI min value associated with such a power request is
readily found by reference to the Nj min table. For example, if the operator
power request comprises an No value of 1000 rpm and a T0 value of 1500
Newton* Meters, a microprocessor refers to the table for the Nj min values and
simply finds the box having the location 1000, 1500 and extracts the value for
Ni min(a). In like fashion, values for Nj max, PI min, and PI max for the
operator torque request having an No value of 1000 rpm and a To value of
1500 Newton*Meters are readily extracted from the other three tables. As one
of ordinary skill in the art readily recognizes, the number of plots generated
being 2500 in this one example was chosen for illustrative purposes, and any
desired number of plots may be generated. The values of the parameters No
and To in the example of FIG. 12 are discrete numbers, and for determining
numerical values of No and To which reside between the values of the rows
and columns, simple mathematical interpolation is employed.
[0062] Thus, a method for determining a set of values for NI min, Nj max, Pi
min, and PI max for input to a 2-D search engine such as 410 has been
provided, and these values of NI min, NI max, PI min, and PI max are
sufficient to define search range space S having a substantially smaller size
than what is otherwise provided by a system as described herein. This
decreased size of the space S provided by a method according to this
disclosure translates to decreased demand on computer resources and
accordingly results in more efficient searching and faster pinpointing of exact
operating points for potential transmission operating modes.


[0063] It is understood that modifications are allowable within the scope of
the disclosure. The disclosure has been described with specific reference to
the preferred embodiments and modifications thereto. Further modifications
and alterations may occur to others upon reading and understanding the
specification. It is intended to include all such modifications and alterations
insofar as they come within the scope of the disclosure.

CLAIMS
1. Method for decreasing the size of a space from within which a two-
dimensional search engine selects points defined by numerical pairs for
evaluation, said space comprising at least one two-dimensional first
region, said first region having minimum and maximum abscissa and
ordinate values associated with it, said method comprising:
generating a plurality of contour plots, said contour plots having abscissa
and ordinate axes, and comprising contours which are representative
of a property associated with points within the first region bounded
by said abscissa and ordinate axes;
selecting a second region from each of said contour plots, said second
regions each comprising minimum and maximum abscissa values
and minimum and maximum ordinate values;
providing four tables of data, the data in each table of said four tables
comprising one of four variables selected from the group consisting
of: said minimum abscissa value, said maximum abscissa value, said
minimum ordinate value, and said maximum ordinate value;
providing a two-dimensional input request;
extracting a value for each of said minimum abscissa value, said
maximum abscissa value, said minimum ordinate value, and said
maximum ordinate value from said tables, to provide extracted
values based upon said input request; and
defining a search space based on said extracted values.

2. A method as in claim 1 further comprising:
searching said search space to determine a desirable point, based on any
pre-selected criteria.
3. A method as in claim 2 wherein said searching is conducted using an
algorithm.
4. A method as in claim 1 wherein said property is power loss associated
with a drivetrain for points located within said first region, said first
region having coordinates of transmission input speed and transmission
input power.
5. A method as in claim 1 wherein said numerical pairs each comprise a
transmission input speed value and a transmission input power value.
6. A method as in claim 1 wherein said numerical pairs selected for
evaluation are each associated with a value obtained by summing at least
two power losses associated with a driveline of a motorized vehicle
when operating in a continuously-variable mode at points represented by
said numerical pairs within said space.
7. A method as in claim 1 wherein said input request comprises two
coordinates, said two coordinates comprising at least one of the same
coordinates used as a defining variable in each table of said four tables.

8. A method as in claim 1 wherein said second region comprises less area
on a two-dimensional plane than said first region.
9. A method as in claim 1 wherein said first region undergoes a change of
position within said two-dimensional plane as a function of time.
10. Method for controlling a powertrain system which includes an engine,
and a transmission, the transmission operative in one of a plurality of
operating modes to transfer power between the engine and an output
member, the method comprising:
defining a two-dimensional space within which space resides candidate
operating points for said transmission, the candidate operating points
each comprising a transmission input speed and a transmission input
power value;
searching said two-dimensional space to determine an operating point to
be chosen based on pre-selected criteria; and
selectively commanding said powertrain system to operate using a
transmission input speed and a transmission input power value
associated with a chosen point from within said two-dimensional
space.
11. A method according to claim 10 wherein said pre-selected criteria
includes a summation of at least two power losses associated with said
powertrain system.

12. A method according to claim 10 further comprising:
defining a smaller two-dimensional space within said two-dimensional
space within which said searching is to be carried out.
13. A method according to claim 12 further comprising:
searching said smaller two-dimensional space to determine an operating
point to be chosen based on pre-selected criteria.
14. A method according to claim 13 further comprising subsequently
selectively commanding said powertrain system to operate using a
transmission input speed and a transmission input power value
associated with a chosen point from within said smaller two-dimensional
space.
15. A method according to claim 12 wherein said smaller two-dimensional
space is determined by off-line simulations of operating parameters
which are provided in reference to said powertrain system.
16. A method according to claim 15 wherein at least one of said operating
parameters is subjective.
17. A search method for determining a desirable input speed for a
transmission in a combination that comprises at least one torque actuator


mechanically coupled to said transmission, said torque actuator
contributing to the input speed of said transmission, comprising:
selecting a potential operating point for said at least one torque actuator
from a search range, said potential operating point having associated
with it a transmission input speed value and a transmission input
power value;
determining a plurality of power losses associated with operation of said
combination at said potential operating point;
combining said power losses of said plurality, to provide a total power
loss;
repeating said selecting, said determining, and said combining, to
provide a plurality of potential operating points, each of which have
a respective total power loss associated therewith;
evaluating said plurality of potential operating points for desirability,
based on at least one criteria selected from the group consisting of:
objective operating criteria and subjective operating criteria; and
selecting one operating point from said plurality of potential operating
points;
said search method being conducted under the constraint of maintaining
the output power of said transmission at least substantially-constant,
and optionally, constant.
18. A method according to claim 17, further comprising:
selectively commanding a change in the transmission operating range
state based on said one operating point selected.

A microprocessor driven two dimensional search engine examines
transmission operating points within a plurality of search range spaces and
assists in determining properties associated with the driveline at various
operating points within the space. The size of the space is reduced by
rearrangement of data.

Documents:

1886-KOL-2008-(06-01-2015)-PETITION UNDER RULE 137.pdf

1886-KOL-2008-(30-05-2014)-ABSTRACT.pdf

1886-KOL-2008-(30-05-2014)-CLAIMS.pdf

1886-KOL-2008-(30-05-2014)-CORRESPONDENCE.pdf

1886-KOL-2008-(30-05-2014)-DESCRIPTION (COMPLETE).pdf

1886-KOL-2008-(30-05-2014)-DRAWINGS.pdf

1886-KOL-2008-(30-05-2014)-FORM-1.pdf

1886-KOL-2008-(30-05-2014)-FORM-2.pdf

1886-KOL-2008-(30-05-2014)-FORM-3.pdf

1886-KOL-2008-(30-05-2014)-FORM-5.pdf

1886-KOL-2008-(30-05-2014)-OTHERS.pdf

1886-KOL-2008-(30-05-2014)-PETITION UNDER RULE 137.pdf

1886-kol-2008-abstract.pdf

1886-KOL-2008-ASSIGNMENT.pdf

1886-kol-2008-claims.pdf

1886-kol-2008-CORRESPONDENCE-1.1.pdf

1886-KOL-2008-CORRESPONDENCE-1.2.pdf

1886-kol-2008-correspondence.pdf

1886-kol-2008-description (complete).pdf

1886-kol-2008-drawings.pdf

1886-kol-2008-form 1.pdf

1886-kol-2008-form 18.pdf

1886-kol-2008-form 2.pdf

1886-kol-2008-form 3.pdf

1886-kol-2008-form 5.pdf

1886-kol-2008-gpa.pdf

1886-kol-2008-specification.pdf

1886-kol-2008-TRANSLATED COPY OF PRIORITY DOCUMENT.pdf

abstract_1886-kol-2008.jpg


Patent Number 266024
Indian Patent Application Number 1886/KOL/2008
PG Journal Number 14/2015
Publication Date 03-Apr-2015
Grant Date 27-Mar-2015
Date of Filing 03-Nov-2008
Name of Patentee GM GLOBAL TECHNOLOGY OPERATIONS, INC.
Applicant Address 300 RENAISSANCE CENTER, DETROIT, MICHIGAN
Inventors:
# Inventor's Name Inventor's Address
1 KEE YONG KIM 1699 SCIO RIDGE RD. ANN ARBOR, MI 48103
2 ANTHONY H. HEAP 2969 LEWSLIE PARK CIRCLE, ANN ARBOR, MICHIGAN 48105
3 BIN WU 981 DURHAM CT. TROY, MI 48084
PCT International Classification Number G06F17/30
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 60/985227 2007-11-03 U.S.A.