U.S. patent application number 09/748050 was filed with the patent office on 2001-05-10 for recursive vehicle mass estimation apparatus and method.
Invention is credited to Bailey, Thomas L., Taylor, Dennis O., Zhu, G. George.
Application Number | 20010001138 09/748050 |
Document ID | / |
Family ID | 22062216 |
Filed Date | 2001-05-10 |
United States Patent
Application |
20010001138 |
Kind Code |
A1 |
Zhu, G. George ; et
al. |
May 10, 2001 |
Recursive vehicle mass estimation apparatus and method
Abstract
A method and apparatus is disclosed for recursively estimating
vehicle mass and/or aerodynamic coefficient of a moving vehicle.
The vehicle speed and push force data are collected and a segment
of qualified data is then selected from the collected data.
Newton's second law is integrated to express vehicle mass and/or
aerodynamic coefficient in terms of vehicle push force and vehicle
speed. This expression is then used in a recursive analysis of the
qualified data segment to determine an estimated vehicle mass
and/or aerodynamic coefficient.
Inventors: |
Zhu, G. George; (Columbus,
IN) ; Taylor, Dennis O.; (Columbus, IN) ;
Bailey, Thomas L.; (Columbus, IN) |
Correspondence
Address: |
Douglas A. Collier
Woodard, Emhardt, Naughton, Moriarty and McNett
Bank One Center/Tower
111 Monument Circle, Suite 3700
Indianapolis
IN
46204-5137
US
|
Family ID: |
22062216 |
Appl. No.: |
09/748050 |
Filed: |
December 22, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09748050 |
Dec 22, 2000 |
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09065366 |
Apr 23, 1998 |
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6167357 |
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Current U.S.
Class: |
702/175 ;
73/865 |
Current CPC
Class: |
B60T 8/172 20130101;
B60T 2250/02 20130101; G01G 19/086 20130101 |
Class at
Publication: |
702/175 ;
73/865 |
International
Class: |
G01G 019/03 |
Claims
What is claimed is:
1. A method of estimating the mass of a vehicle, the vehicle
including an internal combustion engine, the engine producing a
torque in accordance with a fueling rate provided by a fueling
system thereof, the torque being applied to a drive-train coupled
to the engine, the drive train including a transmission coupled to
the engine having a plurality of engageable gear ratios, a drive
axle and a propeller shaft coupling the drive axle to the
transmission, the drive axle including at least one wheel for
moving the vehicle, the method comprising: (a) periodically
determining a vehicle speed and a vehicle push force corresponding
to the vehicle speed and storing corresponding vehicle speed and
vehicle push force data within a memory portion of a control
computer; (b) qualifying a segment of the vehicle speed and push
force data; and (c) determining vehicle mass by a recursive least
square estimation analysis of the segment of data by defining the
vehicle speed as a function of the push force.
2. The method of claim 1, further comprising estimating a vehicle
aerodynamic coefficient.
3. The method of claim 2 further comprising correcting the vehicle
mass and the aerodynamic coefficient when at least one of the
vehicle mass and the aerodynamic coefficient is beyond a
predetermined limit.
4. The method of claim 1, wherein said periodically determining the
vehicle speed includes sensing the rotational speed of a vehicle
component.
5. The method of claim 1, wherein said periodically determining the
vehicle push force includes sensing engine fueling to determine an
engine torque, converting the engine torque to a tire torque based
on an engaged gear ratio, and converting the tire torque to the
vehicle push force.
6. The method of claim 1, wherein said periodically determining
vehicle speed and push force includes determining a shift status,
the shift status corresponding to a determination of vehicle speed
and push force.
7. The method of claim 6, wherein said qualifying includes
buffering the vehicle speed, push force, and shift status data, and
selecting the longest qualified segment therefrom.
8. The method of claim 6, wherein said qualifying includes
establishing a throttle percentage exceeding a threshold
amount.
9. The method of claim 8, wherein said threshold amount is about
30%.
10. The method of claim 6, wherein said qualifying includes
establishing a torque percentage exceeding a threshold amount.
11. The method of claim 6, wherein said qualifying includes
establishing a brake status.
12. The method of claim 6, wherein said qualifying includes
establishing the transmission is in-gear.
13. The method of claim 1, further including adjusting a control
computer parameter in accordance with the estimated vehicle
mass.
14. A control system for estimating mass of a vehicle, the vehicle
including an engine with a fueling system associated therewith, a
transmission coupled to the engine having a plurality of engageable
gear ratios, a drive axle and a propeller shaft coupling the
transmission to the drive axle, the system comprising: means for
determining a vehicle speed and providing a vehicle speed signal
corresponding thereto; means for determining an engine fueling rate
and providing an engine fueling rate signal corresponding thereto;
means for determining a presently engaged gear ratio of the
transmission and providing a gear ratio signal corresponding
thereto; and a processor responsive to said engine fueling rate
signal and said gear ratio signal to determine a vehicle push force
corresponding to said vehicle speed signal, said processor being
further responsive to qualify a data segment therefrom and
calculate an estimated vehicle mass, said estimated vehicle mass
being determined by a recursive analysis of said data segment and
establishing said vehicle speed as a function of said push
force.
15. The system of claim 14, further including means for determining
a throttle percentage corresponding to said vehicle speed and
vehicle push force, said data not being qualified when said
throttle percentage is less than a threshold requirement.
16. The system of claim 15, wherein said threshold requirement is a
throttle percentage of about 30%.
17. The system of claim 15, wherein qualification of said data
segment includes establishing a torque percentage exceeding a
threshold amount.
18. The system of claim 15, wherein qualification of said data
segment includes establishing a brake status.
19. The system of claim 14, wherein qualification of said data
segment requires the transmission to be in-gear.
20. The system of claim 14, wherein said processor is operable to
further calculate an estimated vehicle aerodynamic coefficient from
said function.
21. The system of claim 14, wherein said processor is further
operable to correct said estimated vehicle mass and aerodynamic
coefficient when either one is beyond a predetermined limit.
22. The system of claim 14, further including a data communications
link connected to said processor, and wherein at least one of said
engine fueling rate signal, said vehicle speed signal, and said
gear ratio signal is provided to said processor from a remote
processor with said data communications link.
23. The system of claim 14, wherein said processor being further
operable to sense engine fueling to determine an engine torque,
converting the engine torque to a tire torque based on an engaged
gear ratio, and converting the tire torque to the vehicle push
force.
24. A system, comprising: a vehicle including an engine with a
fueling system, a transmission coupled to said engine having a
plurality of engageable gear ratios, a drive axle, and a propeller
shaft coupling said transmission to said drive axle; a vehicle
speed sensor, said sensor providing a speed signal corresponding to
speed of the vehicle; a programmable processor with a memory
portion operatively coupled thereto, said processor being
responsive to an engine fueling rate signal and a gear ratio signal
stored in said memory to determine a vehicle push force
corresponding to said speed signal, said processor being programmed
to qualify a data segment from vehicle speed and vehicle push force
to calculate an estimated vehicle mass, said estimated vehicle mass
being determined by a recursive analysis of said data segment and
establishing said vehicle speed as a function of said push
force.
25. The system of claim 24, further including a throttle percentage
stored in said memory corresponding to said vehicle speed and
vehicle push force, said data segment not being qualified when said
throttle percentage is less than a threshold requirement.
26. The system of claim 25, wherein said threshold requirement is a
throttle percentage of about 30%.
27. The system of claim 24, wherein qualification of said data
segment includes establishing a torque percentage exceeding a
threshold amount.
28. The system of claim 24, wherein qualification of said data
segment includes establishing a brake status.
29. The system of claim 24, wherein said data is not qualified if a
gear is not presently engaged.
30. The system of claim 24, wherein said processor is operable to
further calculate an estimated vehicle aerodynamic coefficient from
said function.
31. The system of claim 24, wherein said processor is further
operable to correct said estimated vehicle mass and aerodynamic
coefficient when one of said estimates is outside an upper or lower
limit.
32. The system of claim 24, further including a data communications
link connected to said processor, and any of said engine fueling
rate signal, said vehicle speed signal or said gear ratio signal
being provided to said processor from a remote processor via said
data communications link.
33. The system of claim 24, wherein said processor is further
operable to sense an engine fueling to determine an engine torque,
convert the engine torque to a tire torque based on an engaged gear
ratio, and convert the tire torque to the vehicle push force.
Description
FIELD OF THE INVENTION
1. This invention relates in general to control systems for
vehicles and more specifically to vehicle mass estimation
techniques.
BACKGROUND OF THE INVENTION
2. The determination of vehicle mass is important to the efficient
operation of today's vehicles, especially in the heavy-duty
commercial and industrial truck industries. For example, mass can
be a selection criteria for proper gear changing control in a
transmission having staged gears. Vehicle mass may also be used by
various vehicle controllers in anti-lock brake systems, intelligent
vehicle/highway systems and fleet management systems, to name a
few. In addition, vehicle mass can be useful in speed control
systems, such as for use with a cruise control system. One problem
with using vehicle mass as a control parameter is that it varies
with vehicle loading and is usually difficult to predict with
certainty, especially with respect to heavy-duty trucks. For
example, a dump truck can have a mass when loaded up to ten tons
greater than when empty. In the case of a semi-tractor with a
trailer, the mass when loaded can be up to 40 tons greater than
when empty.
3. Because the mass of a particular vehicle may vary greatly, a
means for accurately measuring actual vehicle mass when the vehicle
is in operation is required if the dynamic vehicle mass is to be
used as a control parameter. Thus, if the mass parameter is fixed
at a particular value in the control system, then the various
control features described above will not allow for optimal vehicle
performance under all types of load conditions.
4. Various methods of measuring vehicle mass have been the subject
of prior patents. In U.S. Pat. No. 5,490,063 to Genise, a method
for determining vehicle mass as a function of engine output or
driveline torque, vehicle acceleration, and the currently engaged
gear ratio is disclosed. For this method, Newton's law is used
directly with acceleration and force values determined from the
torque and gear ratio input to estimate vehicle mass. Likewise, in
U.S. Pat. No. 4,548,079 to Klatt, a method is disclosed for
determining vehicle mass directly using engine output torque values
and acceleration values.
5. Vehicle acceleration is typically computed from either engine or
vehicle speed data. However, one of the problems associated with
the collection of speed data is that speed signal is typically very
noisy. When vehicle acceleration is used to determine the vehicle
mass, the noise problem is even more significant. In order to
determine acceleration, it is often necessary to measure the
increase or decrease in speed values at very close time intervals.
This differentiation in speed values at close time intervals causes
the acceleration signal to be buried in the noise of the speed
signal. Inaccurate determinations of vehicle acceleration and a
correspondingly inaccurate determination of vehicle mass may
result. The various controllers relying on an accurate vehicle mass
determination may in turn perform ineffectively and
inefficiently.
6. What is therefore needed is a technique for estimating vehicle
mass that addresses the foregoing shortcomings. Such a technique
should provide reliable, accurate estimates of vehicle mass. The
method should also effectively address the problems created by the
inherent noise contained in speed signal data. The technique should
also be inexpensive to implement, and be readily integratable into
existing vehicle control systems.
SUMMARY OF THE INVENTION
7. The present invention addresses the foregoing shortcomings in
estimating vehicle mass. In accordance with the present invention,
a technique for processing vehicle speed signal data and vehicle
push force data to estimate vehicle mass is disclosed. The
technique results in an accurate and reliable estimate of vehicle
mass and/or aerodynamic coefficient. The technique also minimizes
the effects of speed signal noise in the computation of vehicle
mass.
8. In accordance with one aspect of the present invention, a method
is disclosed for estimating the mass of a vehicle that has an
internal combustion engine producing a torque in accordance with a
fueling rate provided by a fueling system thereof. The torque is
applied to a drive-train coupled to the engine. The drive train
includes a transmission coupled to the engine that has a plurality
of engageable gear ratios, a drive axle, and a propeller shaft
coupling the drive axle to the transmission. The drive axle has at
least one wheel for moving the vehicle. This method includes: (a)
continually determining a vehicle speed and a vehicle push force
corresponding to the vehicle speed and storing corresponding
vehicle speed and vehicle push force data within a memory portion
of a control computer; (b) qualifying a segment of the vehicle
speed and push force data; and (c) determining vehicle mass by a
recursive least square estimation analysis of the qualified segment
of data by defining the vehicle speed as a function of the push
force. A vehicle aerodynamic coefficient may also be
determined.
9. In another aspect of the invention, the determination of vehicle
speed and push force includes determining a shift status.
Additionally, the qualification of the data segment may include
buffering the vehicle speed, push force, and shift status data, and
selecting the longest qualified segment therefrom. The invention
may further include correcting the estimated vehicle mass and
aerodynamic coefficient when one of the estimates falls outside an
upper or lower limit.
10. In a further aspect, a control system for a vehicle is
disclosed for estimating mass of the vehicle. The control system
includes an engine with a fueling system associated therewith, a
transmission coupled to the engine having a plurality of engageable
gear ratios, a drive axle, and a propeller shaft coupling the
transmission to the drive axle. The system further has means for
determining a vehicle speed and providing a vehicle speed signal
corresponding thereto; means for determining an engine fueling rate
and providing an engine fueling rate signal corresponding thereto;
means for determining a presently engaged gear ratio of the
transmission and providing a gear ratio signal corresponding
thereto; and a processor responsive to the engine fueling rate
signal and the gear ratio signal to determine a vehicle push force
corresponding to the vehicle speed signal. The processor is further
responsive to qualify a data segment from these signals and
calculate an estimated vehicle mass by a recursive analysis of the
qualified data segment, where the vehicle speed is expressed as a
function of push force.
11. In another aspect of the present invention, the control system
further includes a data communications link connected to the
processor, with the engine percentage torque, the vehicle speed
signal, the gear ratio signal, or the gear engagement signal being
provided to the processor from a remote processor via the data
communications link.
12. It is one object of the present invention to provide a
technique for filtering and qualifying speed signal data and push
force data so it may be used to accurately estimate vehicle
mass.
13. It is another object of the present invention to provide a
technique for recursively analyzing speed and push force data to
estimate vehicle mass and/or aerodynamic coefficient which
minimizes effects of external factors and the error associated with
estimates based on little data.
14. Another object of the present invention is to provide a mass
and/or vehicle aerodynamic coefficient estimation technique that is
readily integratable into existing control systems.
15. It is yet another object of the present invention to optimize
the performance and efficiency of vehicle systems and components by
providing accurate estimates of vehicle mass and/or aerodynamic
coefficient.
16. These and other objects of the present invention will become
more apparent from the following description of the preferred
embodiment.
BRIEF DESCRIPTION OF THE DRAWINGS
17. FIG. 1 is a block diagram illustration of one preferred
embodiment of a vehicle control system in accordance with the
present invention.
18. FIG. 2 is a flowchart of one preferred embodiment of a mass
estimation algorithm executable by a controller of the control
system of FIG. 1.
19. FIG. 3A is a graph illustrating an estimate of mass of a moving
vehicle utilizing the principles of the present invention.
20. FIG. 3B is a graph illustrating an estimate of an aerodynamic
coefficient of the same vehicle as utilized in FIG. 3A in
accordance with the principles of the present invention.
21. FIG. 3C is a graph of the RLS covariances for the estimates of
FIGS. 3A and 3B.
22. FIG. 3D is a graph of vehicle speed corresponding to the
estimates of FIGS. 3A and 3B.
23. FIG. 3E is a graph of the fueling rate and throttle percentage
of the vehicle for the estimates of FIGS. 3A and 3B.
24. FIG. 3F is a graph of engaged gear ratio and shift status of
the vehicle for the estimates of FIGS. 3A and 3B.
DESCRIPTION OF THE PREFERRED EMBODIMENT
25. For the purposes of promoting an understanding of the
principles of the present invention, reference will now be made to
the embodiment illustrated in the drawings and specific language
will be used to describe the same. It will nevertheless be
understood that no limitation of the scope of the present invention
is thereby intended, any alterations and further modifications in
the illustrated systems, and any further applications of the
principles of the present invention as illustrated therein being
contemplated as would normally occur to one skilled in the art to
which the present invention relates.
26. Referring now to FIG. 1, an engine control system for measuring
vehicle mass and providing a signal corresponding thereto to
regulate various operational parameters in accordance therewith,
all in accordance with the present invention, is shown and
designated generally at 10. Central to control system 10 is a
control computer 12 which interfaces with various components of a
motor vehicle. Control computer 12 is preferably
microprocessor-based and includes a memory portion 15, a digital
I/O, a number of analog-to-digital (A/D) inputs, and at least one
communications port (COM) such as the Universal Asynchronous
Receiver/Transmitter (UART) variety and SAE J1939 datalink.
27. The microprocessor portion of control computer 12 runs software
routines and manages the overall operation of control system 10.
The present invention contemplates using any one of a number of
known microprocessors capable of managing and controlling control
system 10.
28. The memory portion 15 of control computer 12 may be of one or
more types, including, but not limited to ROM, RAM, EPROM, EEPROM,
flash, electromagnetic, optical, or any other variety of memory
known to those of ordinary skill in the art. Memory portion 15 may
be further supplemented via external memory connected thereto (not
shown).
29. An internal combustion engine 14 is operatively connected to a
main transmission 16 as is known in the art. A propeller shaft, or
tail shaft 18 extends from transmission 16. Transmission 16 is
operable to rotatably actuate propeller shaft 18 to provide driving
power to one or more vehicle wheels 52 connected to a drive axle
50. Transmission 16 may also be operable to actuate power take-off
(PTO) devices and other known drivetrain components.
30. A number of sensors and actuators permit control computer 12 to
interface with some of the various components of control system 10
as well as other vehicle and engine systems. For example, engine 14
includes an engine speed sensor 22 mounted thereto or therein which
is electrically connected to control computer 12 via input IN1.
Engine speed sensor 22 is preferably a known Hall effect device
operable to sense speed and/or position of a toothed gear rotating
synchronously with the engine crank shaft (not shown). However, the
present invention contemplates using any known engine speed sensor
22, such as a variable reluctance sensor, which is operable to
sense engine rotational speed and provide a signal to control
computer 12 corresponding thereto.
31. A vehicle speed sensor 24 is preferably operably connected to
propeller shaft 18 and electrically connected to control computer
12 via input IN2. Alternatively, vehicle speed sensor 24 is
electrically connected to a transmission controller, and control
computer 12 obtains vehicle speed through communication port COM.
In still another embodiment, vehicle speed is determined via global
positioning system (GPS) technology. However, vehicle speed sensor
24 is preferably a variable reluctance sensor operable to sense
rotational speed of propeller shaft 18 and provide a vehicle speed
signal to control computer 12 corresponding thereto. While vehicle
speed sensor 24 is shown in FIG. 1 as being located adjacent to
transmission 16, it is to be understood that sensor 24 may be
located anywhere along propeller shaft 18. The present invention
further contemplates using any other known vehicle speed sensor
operable to provide a vehicle speed signal indicative of forward
(and/or reverse) vehicle velocity. For example, vehicle speed
sensor could be mounted on a hub of a wheel of the vehicle.
32. In one preferred embodiment, both engine speed sensor 22 and
vehicle speed sensor 24 include a marker placed on a rotating
object, such as a crankshaft or wheel. As the object rotates, the
marker passes by a pick-up situated at a predetermined location
along the periphery of the object to generate a corresponding train
of pulses. The rate of these pulses is proportional to the engine
or wheel speed, whichever is being measured. Moreover, by providing
different angular spacing of the markers, crank angle may be
determined from a corresponding difference in the pulse train
spacing. In one example, the markers are provided by the teeth
formed along the periphery of the wheel from a material that causes
a magnetic field perturbation as it moves by the pick-up. The
pick-up is a hall-effect device which generates the pulse train
corresponding to the engine speed. U.S. Pat. No. 5,268,842 to
Marston et al. is cited as an additional source of information
concerning such arrangements. In other embodiments, a different
technique for detecting speed may be employed as would occur to one
skilled in the art.
33. Control system 10 further includes a fuel system 30
electronically controlled by control computer 12, and is preferably
responsive to torque request signals provided by either operator
actuation of an accelerator pedal 26, or generated by control
computer 12 pursuant to some type of computer controlled fueling
condition as is known in the art. Examples of some well known
computer controlled fueling conditions include, but are not limited
to, cruise control operation, auto-starting of the vehicle,
computer commanded fueling when shifting a shift-by-wire type of
transmission 16, and the like. Additionally, a torque request
signal could be provided by an auxiliary computer, and passed to
control computer 12 via datalink 42, which will be discussed in
greater detail hereinafter. In any event, the torque request signal
may be indicative of a signal provided to control computer 12 via
driver actuation of accelerator pedal 26, or a computer-generated
signal generated by control computer 12 or an auxiliary computer
pursuant to some type of computer controlled fueling condition as
described above.
34. Accelerator pedal 26 is preferably mechanically connected via
linkage L, to the wiper W of a potentiometer P. The wiper W is
connected to an A/D input IN3 of control computer 12, and the
position or percentage of accelerator pedal 26 corresponds directly
to the voltage present on wiper W. One end of potentiometer P is
connected to a voltage V.sub.DC, and the other end is connected to
ground potential. The voltage present on wiper W thus ranges from
V.sub.DC to ground potential. Control computer 12 converts the
analog voltage on wiper W to a digital quantity representative of
driver requested torque. The present invention further contemplates
other known sensors associated with accelerator pedal 26 to provide
one or more analog and/or digital signals corresponding to
accelerator pedal position or pressure applied to accelerator pedal
26. In any event, control computer 12 processes the analog and/or
digital accelerator signal(s) provided by accelerator pedal 26 to
provide a torque request signal as described above.
35. A known cruise control system preferably includes switches SW1
and SW2 mounted in the driver's cab or compartment. Switches SW1
and SW2 provide the driver with a means for turning the cruise
control functions on and off via switch SW1 and for establishing a
cruise speed via switch SW2. Switch SW2 also provides input signals
to control computer 12 to actuate resume/acceleration features well
known in the art of cruise control systems. Switch SW1 thus enables
cruise control mode of operation while switch SW2 is used to
activate the operational modes of the cruise control system built
into the software of control computer 12. Switch SW1 is connected
at one end to V.sub.DC, and at its opposite end to input IN6 of
control computer 12 and resistor R1, which is referenced at ground
potential. Input IN6 is thus normally at ground potential while
switch SW1 is open (cruise control is off), while input IN6
switches logic to high voltage (V.sub.DC) when switch SW1 is closed
(cruise control on). Switch SW2 is a momentary center-off Single
Pole Double Throw (SPDT) switch. The center position is connected
to V.sub.DC, a first switch position is connected to control
computer input IN4 and resistor R.sub.3, which is referenced at
ground potential. The remaining position of switch SW2 is connected
to control computer input IN5 and resistor R.sub.2, which is also
referenced at ground potential. The set/coast cruise control
function is activated by shorting input IN4 of control computer 12
to logic high voltage, V.sub.DC. The resume/acceleration feature of
the cruise control system is activated by shorting input IN5 of
control computer 12 to logic high voltage V.sub.DC. These
operational features are activated by driver actuation of switch
SW2 as is known in the art. While the foregoing description is
directed to one preferred cruise control embodiment, it is to be
understood that any cruise control system known to those skilled in
the art is contemplated. In any case, control computer 12 is
responsive to the cruise control signals at inputs IN4, IN5, and
IN6 to determine therefrom a torque request signal as described
above.
36. Regardless of the mechanism controlling the torque request
signal to control computer 12, a governor portion 35 of control
computer 12 is operable to process the torque request signal and
provide an engine fueling signal or fuel rate signal therefrom,
which signal is provided at output OUT1. Output OUT1 is the output
of governor 35 and is connected to the fueling system 30 of the
engine 14. Fueling system 30 may be any conventional fueling system
known to those skilled in the art.
37. One preferred technique for converting the torque request
signal to a fueling signal involves mapping the requested torque to
an appropriate engine fueling rate stored in memory unit 15. While
many factors other than requested torque affect the choice of
engine fueling rate, the appropriate fueling rate information is
converted to a corresponding timing signal provided to engine fuel
system 30 via output OUT1. The present invention contemplates,
however, that other known techniques may be used to convert the
torque request signal to a timing signal suitable for use by engine
fueling system 30. In accordance with the present invention, a
control algorithm is provided to further adjust the appropriate
timing signals to fuel system 30 based on an estimated mass of the
vehicle.
38. Transmission 16 may be any known manual, automatic, or
manual/automatic transmission having a plurality of selectable gear
ratios. For any manually selectable gear ratios, transmission 16
includes a mechanical input 32 coupled via linkage L.sub.G to a
gear shift lever 28 typically located in the cab area of the
vehicle. As is known in the art, gear shift lever 28 is manually
actuated to select any one of a plurality of manual gear ratios of
transmission 16. For any automatically selectable gear ratios,
transmission 16 includes one or more actuators 34 which is/are
electrically connected to output OUT2 of control computer 12. As
shown in FIG. 1, output OUT2 of control computer 12 is connected to
one or more automatic gear actuators 34 via n signal lines, where n
is an integer value indicating the number of signal lines.
Typically, the one or more automatic gear actuators 34 are
electrically actuated solenoids responsive to control signals
provided thereto to control selection of a corresponding automatic
gear ratio of transmission 16.
39. Control system 10 may include various mechanisms for providing
control computer 12 with information relating to the presently
engaged gear ratio of transmission 16. Preferably, memory unit 15
of control computer 12 includes certain information relating to
transmission 16, so that control computer 12 is operable to
determine the presently engaged gear ratio of transmission 16 at
any time the vehicle is moving at a speed sufficient to provide a
valid speed signal. The presently engaged gear ratio is preferably
computed as a ratio of engine speed (provided at input IN1) to
vehicle speed (at input IN2). However, the present invention
contemplates several alternative techniques for determining
presently engaged gear ratio of transmission 16. For example,
transmission 16 may include electrical componentry 36 operable to
provide a signal to input IN7 of control computer 12 via signal
path 38, which signal is indicative of presently engaged gear
ratio. In one embodiment, componentry 36 may include or interface
with a number of micro-switches associated with the various
transmission gears. The collective states of the various switches
may be used to provide a signal indicative of presently engaged
gear ratio. Alternatively, componentry 36 may include transmission
input speed and output speed sensors and a processor operable to
evaluate the transmission input and output speeds to provide a
presently engaged gear ratio signal corresponding thereto. The
present invention further contemplates that any known electrical
componentry 36 may be used to provide a control computer 12 with
information relating to the presently engaged gear ratio of
transmission 16.
40. As another alternative technique for determining the presently
engaged gear ratio of transmission 16, transmission 16 may be
equipped with circuitry 40 operable to determine the operational
state or status of transmission 16, which circuitry may include a
microprocessor 44. A communication bus 42 is connected at one end
to a communication port of microprocessor 44, and at an opposite
end to a communications port COM of control computer 12. Preferably
communications bus or datalink 42 is an SAE (Society of Automotive
Engineers) J1939 standard. According to the J1939 bus industry
standard, control computer 12 and microprocessor 44 are operable to
send and receive information relating to engine, transmission,
and/or vehicle operation. Thus, all information available on
communication bus 42 is available not only to control computer 12
but to microprocessor 44 as well.
41. Microprocessor 44 may use any information available on
communication bus 42, or may use any of the electrical components
within electrical circuitry 40 to determine the status of
transmission 16, such as presently engaged gear ratio, out-of-gear
condition, etc., in accordance with any of the previously discussed
techniques. In one embodiment, microprocessor 44 may then transmit
such gear ratio information over communication bus 42 to control
computer 12 for further processing. Additionally, microprocessor 44
may process and/or compute the torque request signal from
appropriate data and/or signals, provided thereto via datalink 42
and/or other inputs to microprocessor 44, and provide the torque
request signal to control computer 12 via the datalink 42. It
should be further understood that any auxiliary computer connected
to datalink 42 would have access to any and all information
necessary to compute the torque request signal, and could therefore
compute the signal and provide it to control computer 12.
42. Control system 10 may additionally include a brake pedal 60
attached to the vehicle as known in the art. A brake pedal sensor
62 is operable to detect engagement of brake 60 by a driver and
provide a control signal indicative thereof. Brake pedal sensor 62
is electrically connected at input IN9 to control computer 12 via
signal path 64.
43. In one alternate embodiment of the control system 10 of the
present invention, control system 10 includes an acceleration
sensor/system 46 attached to the vehicle 20 and electrically
connected input IN8 of control computer 12 via signal path 48.
Acceleration sensor/system 46 is designed with sufficient
sensitivity to provide control computer 12 with one or more signals
indicative of vehicle acceleration resulting from driver actuation
of accelerator pedal 26. Acceleration sensor/system 46 may be any
known accelerometer or acceleration sensing system capable of
providing control computer 12 with appropriate vehicle acceleration
information.
44. Referring now to FIG. 2, one preferred embodiment of software
algorithm 100 for determining vehicle mass and/or aerodynamic
coefficient, in accordance with the present invention, is presented
in flowchart form. The algorithm of FIG. 2 is preferably executable
by control computer 12. In one preferred embodiment, algorithm 100
is performed at a cycle time of every 4 seconds. However, it should
be understood that algorithm 100 may be performed at any desired
time cycle, so long as the principles of the present invention are
accomplished.
45. In order to promote an understanding of the principles of the
present invention, the stages of routine 100 pertaining to the
gathering, filtering and qualifying of data will now be described
generally. Further description of each stage is provided after the
general description.
46. Control computer 12 continually senses data from various
sensors and devices of control system 10 as described hereinabove.
This data is then filtered and/or converted in order to determine
and group data points in accordance with time. These grouped data
points represent the vehicle speed, the vehicle push force, and the
shift status. The grouped data points are placed into a buffer
until a predefined capacity of the buffer is reached. Each group of
data points is then either qualified or not qualified as described
more fully below. The longest continuous segment of qualified data
points (if any) is then selected from the buffer in order make one
estimate of vehicle mass in accordance with the present
invention.
47. A predetermined number of subsequent groups of data points are
placed in the buffer in order to replace a corresponding number of
the previously qualified data points. In one preferred embodiment,
half of the previously qualified data points are replaced. The mass
of the vehicle is again recursively estimated in accordance with
the present invention. These steps are repeated throughout
operation of the routine 100.
48. It should be noted that the preferred determination of vehicle
push force and vehicle speed of the present invention does not take
into account certain non-ideal aspects of vehicle operation, such
as tire slippage and gear inefficiencies. While such factors
generally have a minor impact, alternative embodiments may account
for these factors to provide a more accurate result. For example,
actual vehicle speed may be determined by subtracting a tire
slippage parameter, and actual vehicle push force may be determined
by subtracting parameters corresponding to tire slippage and gear
losses.
49. The routine 100 will now be described in detail. Routine 100
starts at stage 102 and continues at stage 104, where control
computer 12 receives data sensed by the various actuators and
sensors described above. It should be understood that the data of
stage 104 is sensed several times per second. In one preferred
embodiment, the data of stage 104 is sensed 100 times per second.
Other embodiments anticipate data readings at other frequencies as
known to those of skill in the art.
50. The data gathered at stage 104 will now be described in detail.
The vehicle speed, indicated as V.sub.S, is an indication of the
speed of the vehicle preferably provided by vehicle speed sensor
24. The engine fueling rate is indicated by EF. Typically, the
signal corresponding to EF is delayed due to the time required for
fuel system responses and combustion of the fuel. Fuel system delay
is a function of the type of engine, the type of fuel system, and
other operating parameters associated therewith.
51. The control computer 12 also receives signals corresponding to
the engaged gear ratio of the transmission which is designated as
GR. Each gear ratio of a transmission has a gear path associated
therewith, as known in the art. The control computer also senses
the amount of throttle that is currently engaged, designated as
TH%, by the operator of the vehicle. The throttle percentage is
determined by accelerator pedal position as described hereinabove.
Alternatively, the throttle percentage may be replaced by the
determination of torque percentage (engine load). Torque percentage
is defined as the current engine fueling divided by the maximum
engine fueling.
52. The control computer 12 also senses the gear status of the
transmission, designated as GS. The gear status is a determination
of whether the transmission is engaged in a current gear or is in
between gear changes. Finally, the average vehicle acceleration,
designated as ACC, may be determined by any known technique. In the
preferred embodiment, average vehicle acceleration is determined by
calculating the difference between the maximum and minimum vehicle
speeds stored in the buffer. Other alternate embodiments
contemplate other techniques for determining average vehicle
acceleration, including differentiating the vehicle speed over
time, relating the change in engine speed to vehicle acceleration,
or determining vehicle acceleration by an acceleration sensor as
discussed hereinabove.
53. From stage 104, routine 100 continues at stage 106 where the
data gathered in stage 104 is filtered by control computer 12 to
determine and/or compute vehicle speed (V.sub.s') push force (Fp),
and shift status (SS). V.sub.S' is the vehicle speed gathered at
stage 104 that has been filtered in order to reduce or eliminate
noise in the vehicle speed signal provided by sensor 24. It is well
known in the art that many factors may cause noise in the vehicle
speed signal, including, but not limited to, road conditions, wind,
and other forces external and internal to the vehicle, as well as
noise inherent in analog sensor based systems. Thus, it is
sometimes necessary to employ various techniques to reduce or
eliminate these effects. In one embodiment, the noise is reduced by
averaging vehicle speed signal readings to produce a single
reading. In one preferred embodiment of the present invention, the
filtered vehicle speed is determined as an average of ten speed
readings. Other embodiments contemplate averaging any different
number of speed readings or such other filtering techniques as
would occur to those skilled in the art. In addition to filtering,
any conversions necessary to convert vehicle speed from, for
example, miles per hour to meters per second are performed in
converting V.sub.S to V.sub.S.
54. Engine fueling is used to calculate the push force (Fp) of the
vehicle. As discussed previously, the engine fueling signal is
delayed so that it corresponds to the vehicle speed readings. In
the preferred embodiment, engine fueling is internally calculated
by control computer 12. Alternate embodiments contemplate an engine
fueling signal that is noisy, similar to the vehicle speed readings
as discussed above. Thus, any known filtering technique, including
averaging any number of engine fueling signals may likewise be
performed.
55. After obtaining an engine fueling signal, the fueling signal is
converted to engine output torque using known equations programmed
into control computer 12 relating engine fueling to engine output
torque. In general, engine torque is a function of fueling, engine
speed, timing, air temperature, intake manifold pressure, etc. For
simplification, it is preferred to estimate engine torque as a
function of engine fueling only, using constants to approximate the
other variables. In one embodiment, engine fueling and engine
output torque are linearly related. Other embodiments contemplate
different relationships, which depend in part on the type of engine
and fuel system involved. The conversion may also be performed by
using one or more schedules, tables, or graphs relating engine
output torque to engine fueling. Engine output torque is then
converted to tire torque by multiplying engine output torque by the
currently engaged gear ratio and axle gear ratio. The tire torque
is then multiplied by the radius of one of the tires to obtain
vehicle push force, (Fp). Thus, stage 106 results in a grouping of
data which has been filtered and/or calculated, the grouped data
including at least a vehicle speed, V.sub.S', and a vehicle push
force, Fp, each corresponding to a single point in time. The
grouped data is stored in control computer 12.
56. Also determined at stage 106 is the shift status, designated as
SS, which may be additionally grouped with vehicle speed and push
force. The shift status is a qualification condition or value
determined by observing three requirements: the throttle percentage
(TH%), brake status (BS), and gear status (GS) sensed at stage 104.
In one preferred embodiment, the throttle percentage is required to
be at least 30% in order to ensure an accurate vehicle push force
calculation. Other embodiments contemplate use of any other
throttle percentage, so long as risk of external forces applied to
the vehicle is minimized. Additionally, the use of throttle
percentage may be replaced with a determination of percentage
torque as discussed hereinabove. A second requirement, or
qualification condition, is that the brake not be engaged. A brake
torque applied to the wheels of the vehicle would cause an error in
the push force calculation. A third requirement, or qualification
condition, for shift status is that the transmission not be
performing a gear change, or be out of gear. This is due to
inaccuracies that may result in the push force calculation when one
of the computers (12, 44) takes over control of engine fueling
during a gear change, for example. Thus, if the throttle percentage
threshold requirement is not met, the brake is engaged, or the
transmission is engaged in a gear change, shift status is assigned
a value of 1. For all other conditions, shift status is assigned a
value of 0.
57. Once the data has been filtered in accordance with stage 106,
routine 100 proceeds at stage 108, where the filtered data is
buffered into three buffer blocks by control computer 12. One
buffer block is assigned to each of filtered vehicle speed
(V.sub.S'), push force (Fp), and shift status (SS). The size of the
buffer may be established to include virtually any number of data
points. In one embodiment, each buffer block is sized to include
two times the number of data points collected between runs of
algorithm 100. For example, if routine 100 is designed to run every
four seconds, and data is filtered every 10 hertz, then there will
be 40 new data points corresponding to each of vehicle speed, push
force, and shift status each time routine 100 is performed.
However, each buffer will include 80 data points, so 40 data points
from the previous run of routine 100 will be included in the
subsequent run of routine 100. Thus, routine 100 is run every 4
seconds using 80 data points. This approach ensures that all data
is analyzed more than a single time by crossing the sample
periods.
58. The routine 100 proceeds from stage 108 at stage 110, where the
buffered data of stage 108 are qualified to certain threshold
requirements. The data meeting the threshold requirements are
determined to be qualified data. In order to meet the threshold
requirements, the data must meet the following conditions: 1) shift
status must be equal to 0; and 2) the average vehicle acceleration
must be greater than a predetermined threshold. In addition, other
conditions may be imposed in order to minimize road condition
effects, etc., by requiring that vehicle speed be within certain
ranges. The shift status requirement assures that transmission 16
is in-gear and a minimum throttle condition is being met as
discussed above. The acceleration threshold is necessary to ensure
the vehicle is not in a deceleration mode. It should be understood
that these threshold qualification requirements for the qualified
data may be varied, in a manner known to those skilled in the art,
so long as the data is capable of being reliably used to estimate
vehicle mass in accordance with the principles of the present
invention.
59. Other conditions may additionally be imposed on the filtered
and buffered data before it may be further processed. For example,
if a pair of data points is determined to be qualified, it is
grouped with surrounding qualified data points, if any, in order to
define a segment of a number of consecutive qualified data points.
A segment of consecutive qualified data points requires that all
data pairs of push force and vehicle speed in that segment meet the
threshold requirements of acceleration and shift status (or any
other threshold requirements deemed necessary). Thus, a block of
buffered data may include many, one, or no qualified data segments.
If there are no qualified data segments, algorithm execution is
terminated and returned to step 102 for the sensing, filtering, and
buffering of an additional cycle of data points as described above.
If there is more than one qualified data segment, then the longest
data segment is selected. In one embodiment, the qualified data
segment must include at least 25 pairs of consecutive data points
meeting the threshold qualification requirements, as discussed
above. However, other embodiments contemplate qualified data
segments including any number of data points.
60. If a qualified data segment is found and selected by control
computer 12 at step 110, the algorithm 100 then proceeds at step
112. Step 112 involves a recursive least square (RLS) estimate of
vehicle mass and aerodynamic coefficient using data points from the
qualified data segment. In order to relate the push force of the
vehicle to vehicle speed, control computer 12 uses an integrated
Newton's second law. Newton's second law may be written as
follows:
F=m.multidot.{dot over (V)}+c.multidot.V
61. Where F is vehicle push force, m is vehicle mass, {dot over
(V)} is vehicle acceleration, V is vehicle speed, and c is the
vehicle aerodynamic coefficient. For purposes of the present
invention, the effect of road grade is ignored.
62. In order to relate vehicle force in terms of vehicle speed, it
is necessary to integrate the above equation in order to eliminate
{dot over (V)}. This results in the following equation:
.intg..sub.T1.sup.T2
F.multidot.dt=m.multidot.[V(T.sub.2)-V(T.sub.1)]+c.mu-
ltidot..intg..sub.T1.sup.T2 Vdt
63. where F and V are the vehicle push force and speed at time
T.
64. Now suppose that nxm data points are sampled at 1/T HZ, and let
F.sub.INT (i) and V.sub.INT(i) represent the integrated push force
and vehicle speed between (k-1).multidot.m.multidot.T and
k.multidot.m.multidot.T 1 F INT ( k ) = ( k - 1 ) m T k m T F t = j
= ( k - 1 ) m k m - 1 F ( j - T ) T V INT ( k ) = ( k - 1 ) m T k m
T V t = j = ( k - 1 ) m k m - 1 V ( j - T ) T
65. Let V(k) represent the vehicle speed at
k.multidot.m.multidot.T, then the following equation states the
relationship between push-force speed, mass, and aerodynamic
coefficient of the vehicle: 2 [ F INT ( 1 ) F INT ( 2 ) F INT ( n1
) ] = [ V ( 1 ) - V ( 0 ) V INT ( 1 ) V ( 2 ) - V ( 1 ) V INT ( 2 )
V ( n ) - V ( n - 1 ) V INT ( n1 ) ] [ m c ] T
66. now let 3 F _ = [ F INT ( 1 ) F INT ( 2 ) F INT ( n1 ) ] and V
_ = [ V ( 1 ) - V ( o ) V INT ( 1 ) V ( 2 ) - V ( 1 ) V INT ( 2 ) V
( n ) - V ( n - 1 ) V INT ( n1 ) ]
67. {overscore (F)} and {overscore (V)} are now substituted into
the following cost function that is known to those of skill in the
art:
J=.vertline..vertline.{overscore (F)}-{overscore (V)}.multidot.[m
c].sup.T.vertline..vertline.,
68. where .vertline..vertline.B.vertline..vertline. is a Frobenius
norm of B. The solution to this cost function is determined
according to a well known technique to be the following: 4 [ m c ]
= ( V _ T V _ ) + V _ T F _
69. where ({overscore (V)}.sup.T.multidot.{overscore (V)}).sup.+is
the pseudoinverse of {overscore (V)}.sup.T.multidot.{overscore
(V)}.
70. Thus, Newton's second law may be used to calculate vehicle mass
using the speed data signals and the push force data collected in
the manner previously described.
71. In order to ensure accuracy of the calculation of vehicle mass
and aerodynamic coefficient, it is preferable that a recursive
estimation technique be employed. Such a technique requires the
above-described cost solution to be minimized, which may be
expressed as follows:
min.vertline..vertline.{overscore (F)}-{overscore
(V)}.multidot..THETA..ve- rtline..vertline., .THETA.=[m
c].sup.T
72. The recursive least square solution to the above equation may
be expressed by the following equations, whose origins and
derivation are well known to those skilled in the art.
.epsilon.(i)={overscore (F)}(i)-{overscore (V)}(i){circumflex over
(.THETA.)}(i-1)
{circumflex over (.THETA.)}(i)={circumflex over
(.THETA.)}(i-1)+.gamma.(i)- R.sup.-1(i) {overscore
(V)}.sup.T.epsilon.(i)
R(i)=R(i-1)+.gamma.(i)[{overscore (V)}.sup.T.multidot.{overscore
(V)}-R(I-1)]
73. where .epsilon.(i) is the prediction error, {circumflex over
(.THETA.)}(i) is the current estimate, R(i) is the covariance, and
.gamma. (i) is between 0 and 1 and is known in the art as the
forgetting factor of the recursive algorithm. The above recursive
least square solution is employed continually to update the
solution of mass and aerodynamic coefficient by modifying the
previous solution to accommodate the previous estimation error.
74. In one embodiment, the matrix inverse of inverse R.sup.-1(i)
required by the above equation is solved by analytically expressing
the matrix inverse as follows: 5 R - 1 = [ R 11 R 12 R 21 R 22 ] -
1 = 1 R 11 R 22 - R 12 R 21 [ R 22 R 12 R 21 R 11 ]
75. This expression of the matrix inverse simplifies the
computation of the recursive estimate of vehicle mass and
aerodynamic coefficient.
76. The above described RLS estimation equations are solved by
control computer 12 preferably each time the buffer is half-filled
with new data. The qualified data segment containing the greatest
number of qualified data points is selected from the buffered data.
However, other embodiments contemplate any other selection
techniques for the data stored in the buffer. For example, all
qualified data segments in a buffer may be used to calculate an
estimated vehicle mass and aerodynamic coefficient. Alternatively,
a technique may be employed which selects some or all of the
qualified data points in the buffer in order to estimate vehicle
mass and aerodynamic coefficient. It should be understood that an
estimate of mass and aerodynamic coefficient are recursively
calculated using the push force and vehicle speed data collected,
filtered, and qualified in accordance with the present invention.
The estimates are more accurate than other known techniques since
the recursive analysis calculates and adjusts for estimation error
of a previous estimate. This error is often inherent in vehicle
speed and engine fueling signal data.
77. From step 112 algorithm 100 continues at step 114, where
control computer 12 corrects the RLS solution based on boundaries
estimated for upper and lower limits for mass and vehicle
aerodynamic coefficient. In an alternate embodiment, such a
correction is not made and algorithm 100 proceeds at step 118.
78. At step 116, in case such a correction is employed, there are
basically three situations which may result from the estimation of
vehicle mass and aerodynamic coefficient. First, the RLS solution
may fall outside the limits of both mass and aerodynamic
coefficient. In such a case the solution is abandoned and the limit
values are used as solutions. Second, the RLS solution may be
within the limits prescribed for both parameters. In this case the
RLS solution will be used as the final result. Finally, if either
mass or aerodynamic coefficient determined by the RLS solution
falls outside its limits, the solution will be corrected as
follows.
79. Let {circumflex over (.THETA.)}=[{circumflex over (m)}] and
{overscore (.THETA.)}=[{overscore (m)}{overscore (c)}], where
{circumflex over (.THETA.)} is the original RLS solution, and
{circumflex over (.THETA.)} is the corrected RLS solution. Then 6 [
m _ c _ ] = [ m ^ c ^ ] + R - 1 [ g 1 g 2 ]
80. where g.sub.1 and g.sub.2 are Kuhn-Tucker coefficients. 7 Let R
- 1 = [ R 11 i R 12 t R 21 i R 22 t ]
81. Then each parameter may be corrected as follows:
82. a. When is less than its lower limit (c.sub.LL) 8 c _ = c UL ,
m _ = m ^ + ( c LL - c ^ ) R 12 t R 22 i
83. b. When is greater than its upper limit (C.sub.UL) 9 c _ = c UL
, m _ = m ^ + ( c UL - c ^ ) R 12 t R 22 i
84. c. When {circumflex over (m)} is less than its lower limit
(m.sub.LL) 10 m _ = m LL , c _ = c ^ + ( m LL - m ^ ) R 21 i R 11
i
85. d. When {circumflex over (m)} is greater than its upper limit
(m.sub.UL) 11 m _ = m UL , c _ = c ^ + ( m UL - m ^ ) R 21 t R 11
i
86. If m and c fall outside the limits after completing the above
correction calculations, the RLS solution is abandoned and the
limit values are used as the solution.
87. Once any corrections are made pursuant to step 116, the
algorithm 100 proceeds at step 118 where mass and aerodynamic
coefficient are output. The algorithm 100 then proceeds at step
120, where control computer 12 is returned to step 102 for
processing of new data in accordance with the present
invention.
88. In an alternate embodiment of the present invention, the
aerodynamic coefficient c of the vehicle is a known value and is
programmed into control computer 12 accordingly. This greatly
simplifies the above described algorithm by eliminating one
unknown. Thus, the above described equations may be modified as
follows: 12 F _ = [ F INT ( 1 ) - V INT ( 1 ) c F INT ( 2 ) - V INT
( 2 ) c F INT ( n ) - V INT ( n ) c ] V _ = [ V ( 1 ) - V ( ) V ( 2
) - V ( 1 ) V ( n ) - V ( n - 1 ) ]
89. When the above equations are combined with the RLS estimation
equations, the solution is reduced to a scalar equation and the
solution becomes much simpler.
90. In FIGS. 3A-3F, an example utilizing the techniques of the
present invention to estimate mass and vehicle aerodynamic
coefficient is illustrated. The horizontal axis of each of the
graphs presented in FIGS. 3A-3F correspond to the same time scale
of 140 to 160 seconds. The vertical axis of FIG. 3A corresponds to
vehicle mass in units of 1.times.10.sup.4 Kilograms (Kg). The graph
210 of FIG. 3A illustrates the estimation of vehicle mass in
accordance with the present invention. The recursive estimate is
indicated with line 214. Graph 210 also includes a reference line
212 which is indicative of actual vehicle mass for comparison. As
the leftmost vertical segment of line 214 indicates, algorithm 100
does not determine an estimated mass until a qualified data segment
is located at approximately 148 seconds. A second segment of
qualified data is located at approximately 156 seconds
corresponding to a smaller vertical segment in line 214. This
second qualified data segment corresponds to a second mass
estimate. After this second mass estimate, line 214 is nearly
coincident with line 212. Thus, as graph 210 illustrates, the
present invention provides an advantageous technique to estimate
vehicle mass.
91. In FIG. 3B, a graph of aerodynamic coefficient estimation is
illustrated and designated generally at 220. The vertical axis for
graph 220 is in units of Newtons/meters/seconds (N/m/s). Graph 220
includes an estimate line 222 which is indicative of estimated
aerodynamic coefficient. As the leftmost vertical segment of line
222 indicates, the aerodynamic coefficient is initially calculated
along with vehicle mass at time 148 seconds.
92. The remaining graphs of FIGS. 3C-3F are directed to
illustration of various operational data of the present invention
that correspond to the estimates of FIGS. 3A and 3B. FIG. 3C
includes graph 230, which illustrates the RLS covariance matrix
values for covariance matrix R, indicated by line 232 (r.sub.11),
line 234 (r.sub.12) , and line 236 (r.sub.22) . Lines 232, 234, and
236 each exhibit a stairstep pattern corresponding to the qualified
data segments at about 148 and 156 seconds.
93. FIG. 3D includes graph 240, which illustrates a line 242. Line
242 is depicts vehicle speed in units of Miles Per Hour (MPH) as
indicated by the vertical scale. FIG. 3E illustrates graph 250 that
includes lines 252 and 254. Line 252 depicts fueling rate in units
of cubic millimeters as indicated by the leftmost vertical scale.
Line 254 depicts throttle position in terms of percent as indicated
by the rightmost vertical scale. FIG. 3F illustrates graph 260 that
includes line 262 and line 264. Line 262 depicts the engaged gear
number as indicated by the leftmost vertical scale and line 264
depicts the discrete-valued shift status signal SS as indicated by
the rightmost vertical scale. Collectively, the graphs of FIGS.
3C-3F illustrate the measurement of the various operational data
from the vehicle gathered and processed in accordance with the
present invention.
94. It should be appreciated that as used herein, data, variables,
data points, values, stages, steps, inputs, and outputs each
correspond to a signal within processing equipment of the present
invention. Moreover, the various techniques, stages, steps,
operations, processes, and routines, of the present invention may
be rearranged, substituted, combined, altered, or deleted as would
occur to one skilled in the art without departing from the spirit
of the present invention.
95. While the invention has been illustrated and described in
detail in the drawings and foregoing description, the same is to be
illustrative and not restrictive in character, it being understood
that only the preferred embodiments have been shown and described
and that all changes and modifications, which come within the
spirit of the invention, are desired to be protected.
* * * * *