Simplified powertrain load prediction method and system using computer based models

A simplified method and system for determining a loading condition on a powertrain of a machine resulting from a loading condition on an implement thereof. The method includes the steps of inputting a predetermined plurality of parameter signals representative of the loading condition on the implement into an implement loading model to determine a plurality of implement loading modeled values as a function of the inputted loading parameter signals and inputting the implement loading modeled values into a kinematic linkage model to determine a plurality of modeled linkage loading values as a function of the inputted implement loading modeled values and a plurality of known linkage parameter values and inputting the modeled linkage loading values into a machine powertrain loading model to determine a plurality of powertrain loading modeled values indicative of the loading condition on the powertrain.

TECHNICAL FIELD
 This invention relates generally to a simplified method and system for
 determining torques and speeds of a powertrain for a machine resulting
 from predetermined loading conditions on an implement thereof, and more
 particularly, to a method and system for determining torques and speeds of
 a powertrain for a machine resulting from an implement loading condition
 using computer based models.
 BACKGROUND ART
 Currently, methods for simulating/predicting powertrain loading conditions
 such as component torques and speeds, involve creating a model of the
 machine powertrain system, the machine operator or control inputs, and the
 operating environment or duty cycle. Commonly referred to as
 "forward-solved" techniques, the machine response is governed primarily by
 the operator commands and the load imposed on the machine. When using such
 models, estimates are required regarding the machine operator's control
 inputs to "drive" the machine powertrain system in a manner representative
 of the desired operating work cycle. A limitation of this aspect of the
 forward-solved techniques is that it involves an iterative process wherein
 initial input commands are selected and subsequently modified until the
 desired response is achieved. Furthermore, to get accurate force
 determinations for the implement, a significant amount of model detail is
 typically required, which in turn often makes the model very sophisticated
 and complicated so as to require simulation experts for operation.
 Naturally, as a byproduct of the sophistication and complexity of these
 models, the alteration of these models is a very involved process. As a
 consequence, load prediction modeling using the known forward-solved
 methods is typically very time consuming, making them impractical for many
 applications.
 Accordingly, the present invention is directed to overcoming one or more of
 the problems as set forth above.
 DISCLOSURE OF THE INVENTION
 In one aspect of the present invention, a simplified method for determining
 a loading condition on a powertrain of a machine as a result of a loading
 condition on an implement thereof is disclosed. The present method
 includes the step of inputting a predetermined plurality of parameter
 signals representative of a loading condition on the implement into an
 implement loading model and responsively determining a plurality of
 implement loading modeled values. The method further includes the steps of
 inputting the implement loading modeled values into a kinematic linkage
 model and responsively determining a plurality of modeled linkage loading
 values as a function of the inputted implement loading modeled values and
 a plurality of known linkage parameter values and, inputting the modeled
 linkage loading values into a machine powertrain loading model to
 determine a plurality of powertrain loading modeled values indicative of
 the loading condition on the powertrain.
 In another aspect of the present invention, a system for determining a
 loading condition on a powertrain of a machine resulting from a loading
 condition on an implement thereof using computer based models is
 disclosed. An electronic controller is utilized for inputting a
 predetermined plurality of parameter signals representative of the loading
 condition on the implement into an implement loading model to determine a
 plurality of implement loading modeled values as a function of the
 inputted loading parameter signals. The electronic controller is further
 utilized for inputting the implement loading modeled values into a
 kinematic linkage model to determine a plurality of modeled linkage
 loading values as a function of the inputted implement loading modeled
 values and a plurality of known linkage parameter values, and for
 inputting the modeled linkage loading values into a machine powertrain
 loading model to determine a plurality of powertrain loading modeled
 values indicative of the loading condition on the powertrain.

BEST MODE FOR CARRYING OUT THE INVENTION
 With reference to FIG. 1, a machine 10 which is a typical front end loader
 of well known construction and operation is shown. Machine 10 includes an
 implement 12 which is a conventional bucket defining a bucket interior
 having known dimensions and volume mounted to machine 10 by a linkage
 arrangement 14 including a link 16 connected to implement 12 at pivot
 point 18, linkage arrangement 14 being operable for manipulating implement
 12 for digging and picking up material from a material pile 20 and like
 functions in a conventional manner. Machine 10 further includes a
 conventionally constructed and operable internal combustion engine 22
 connected in driving relation to a powertrain 24 via a torque converter 23
 to an input transfer gear 25. The output of the input transfer gear 25 is
 attached to the transmission input shaft 26 of a transmission 28 of the
 powertrain 24. Transmission 28, in turn, is drivingly connected to a
 transfer unit 30 drivingly connected to a front drive shaft 32 and a rear
 drive shaft 34, front drive shaft 32 being connected in driving relation
 to a front drive axle assembly 36 for driving a pair of front wheels
 represented at 38 having a rolling radius 40. In turn, rear drive shaft 34
 is drivingly connected to a rear drive axle assembly 42 drivingly
 connected to a pair of rear wheels represented at 44 and having a rolling
 radius 46.
 The present method is operable for determining torques and speeds of
 various components of powertrain 24, such as, but not limited to, torque
 and speed on transmission input shaft 26, engine driveshaft 27, torque
 converter output shaft 29, as a result of predetermined loading conditions
 on implement 12, such as, but not limited to, digging and picking up
 material from material pile 20. Here, it should be understood that
 material pile 20 could comprise a wide variety of materials having
 different per unit weights, such as soil, gravel, snow and the like.
 Depending on the nature of the predetermined digging, lifting and
 otherwise moving or interacting with such different materials with
 implement 12 parameters will result in different torques and speeds for
 the powertrain 24 and associated components.
 If the loading parameters are obtained empirically, according to the
 present method, a plurality of sensors represented by sensors 48 and 50
 which are a force sensor and an accelerometer, respectively, are provided
 for sensing a plurality of parameters of the loading conditions of
 implement 12 in real time during a loading operation. Here, the loading
 operation is represented by digging or scooping material from material
 pile 20 and lifting the material. Force sensor 48 is operable for sensing
 forces during the operation of implement 12 and responsively producing and
 communicating signals representative of the forces to a electronic control
 module 52 over wire 54. The force vector on the implement 12 in the
 x-direction is represented by numeral 49 and the force vector on the
 implement 12 in the y-direction is represented by numeral 47. Similarly,
 accelerometer 50 is operable for sensing acceleration of portion of
 implement 12 and responsively producing and communicating signals
 representative thereof over wire 56 to electronic control module 52,
 although it should also be recognized that some parameters such as
 acceleration can also be derived mathematically from other parameters such
 as displacement and speed when known. The acceleration vector on the
 implement 12 in the x-direction is represented by numeral 51 and the
 acceleration vector on the implement 12 in the y-direction is represented
 by numeral 53. The force and acceleration of the implement 12 is a
 function of implement geometry, type of material in the material pile 20,
 rimpull/speed characteristics, traction limit, lift and tilt force limits,
 maximum rack speed and the individual technique of the operator utilizing
 the implement 12. Rimpull is the tractive force that the machine 10 is
 able to generate. Maximum rack speed is equivalent to the maximum tilt
 speed of the implement 12. The equivalent moment 55 produced by the force
 for the implement 12 is defined as the product of the resultant force
 vector of the force vector in the x-direction 49 and the force vector in
 the y-direction 47 times the perpendicular distance from the pivot pin 18.
 Additionally, an optional input device 58 is shown connected to electronic
 control module 52 via wire 60 for inputting more loading parameters into
 electronic control module 52 including, but not limited to such parameters
 as implement type, size, and geometry, material characteristics, such as
 weight per unit volume, rimpull/speed curve maps and traction limit maps
 for wheels 38 and 44, lift and tilt force limits for implement 12, rack
 speed limits, and implement operating style information. Additional
 computations that are utilized can include, but are not limited to, rear
 rimpull 64, front rimpull 66, rear axle force 68 between wheel 44 and a
 surface 62 on which machine 10 is located during the loading operation and
 a front axle force 70 between wheel 38 and a surface 62 on which machine
 10 is located during the loading operation.
 Referring to FIG. 2 as well as FIG. 1, the electronic control module 52 can
 include, but is not limited to, a processor such as a microprocessor,
 however, any of a wide variety of computing devices will suffice. The
 electronic control module 52 preferably includes, but is not limited to, a
 memory device and a clock, and is representative of both floating point
 processors, and fixed point processors.
 The electronic control module 52 can utilize previously received empirical
 data in the form of parameter signals from sensors 48 and 50, and/or
 analytical data from an optional input device 58 as shown by numeral 80.
 This empirical and/or analytical data is then inputted into an implement
 loading model 82 operable to determine modeled values for forces on
 implement 12, moments, and displacements thereof, using simple
 conventional equations such as the force equation F=M.times.A, wherein F
 equals a force to be determined, M equals a mass, and A equals
 acceleration. Therefore, the total force is equal to the summation of the
 rear rimpull force 64 and the front rimpull force 66 minus the summation
 of the force vector of the implement 12 in the x-direction 49 and the
 force vector of the implement 12 in the y-direction 47. This value for
 total force is equal to the mass M times the vector summation of the
 acceleration of implement 12 in the x-direction and the acceleration of
 implement 12 in the y-direction. F.sub.rimpull -F.sub.implement
 =M.times.A.sub.implement. It is important to keep in mind that data can be
 two dimensional or three dimensional.
 The modeled values are then inputted into a kinematic linkage model 84
 along with inputs relating to linkages connecting implement 12 with
 machine 10, such as, but not limited to, dimensions and angular
 orientations of link 16 and other components of linkage arrangement 14
 which can be inputted using input device 86 or stored in electronic
 control module 52 in a memory device as represented at 88. Kinematic
 linkage model 84 then determines a plurality of modeled linkage loading
 values, including, but not limited to, linkage forces and displacements
 using simple conventional kinematic and force equations.
 The determined modeled linkage loading values are then inputted into a
 powertrain loading model 90 operable to determine powertrain loading
 modeled values indicative of the loading condition on elements of the
 powertrain based on known geometric relationships between the various
 components of machine 10, including implement 12, linkage arrangement 14,
 and powertrain 24, again using simple, conventional force and kinematic
 equations. These powertrain loading modeled values are then delivered to
 an output 92.
 A basic relationship is that the summation of torque is equal to the
 angular inertia times the angular acceleration of the powertrain 24.
 .SIGMA.T=I.multidot.A. As merely an illustrative, but nonlimiting example,
 torque acting on transmission input shaft 26 (T.sub.trans.sub..sub.--
 .sub.in) is a function of the gear ratios between shaft 26 and front drive
 axle assembly 36 and/or rear drive axle 42 (depending on whether the
 respective drive axles are engaged), the combination of the rear rimpull
 force 64 at the contact point between the pair of rear wheels 44 and the
 surface 62 and the front rimpull force 66 at the contact point between the
 pair of front wheels 38 and the surface 62 (F.sub.rimpull), the radii 40
 and 46 of wheels 38 and/or 44, and other factors, such as slippage of
 wheels 38 and 44 relative to surface 62, as shown by the following
 equation
EQU (T.sub.trans.sub..sub.-- .sub.in.times.gear
 ratio)-(F.sub.--.sub..sup.rimpull .times.wheel
 radius)=I.times.Alpha.sub.--.sub..sup.wheel
 where I is a calculation based on predetermined lumped inertial constants;
 gear ratio is the total gear reductions between the input shaft 26 and the
 drive axle assembly or assemblies 36 and 42; F.sub.--.sub..sup.rimpull is
 the rimpull force at involved pair of front wheels 38 and/or pair of rear
 wheels 44; and Alpha.sub.--.sub..sup.wheel is the rotational acceleration
 of the involved wheel (sensed or determined mathematically).
 Alpha.sub.--.sub..sup.wheel is a function of the acceleration of the
 implement 12 in the x-direction 51 and the acceleration of the implement
 12 in the y-direction 53 and wheel slip.
 The powertrain load prediction software will now be discussed with
 reference to FIG. 3, which depicts a flowchart 100 representative of the
 computer program instructions executed by the electronic control module 52
 shown in FIG. 2. A programmer skilled in the art could utilize this
 flowchart to program any of a wide variety of electronic
 controllers/computers in a wide variety of programming languages. In the
 description of the flowcharts, the functional explanation marked with
 numerals in angle brackets, &lt;nnn&gt;, will refer to the flowchart blocks
 bearing that number. At program step &lt;110&gt;, predetermined analytical or
 loading parameters of the loading condition on implement 12, for instance,
 force, acceleration, and the like, are produced. The predetermined
 parameter signals are then inputted into the implement loading model to
 determine modeled implement loading values such as forces, moments, and
 displacements &lt;120&gt;. Then, the implement loading modeled values and a
 plurality of linkage/machine frame parameter values are inputted into the
 kinematic linkage model to determine the modeled linkage loading values,
 as shown at program steps &lt;130&gt;. The modeled linkage values are then
 inputted into the powertrain loading model to determine a plurality of
 powertrain loading modeled values indicative of the loading condition on
 the powertrain, as illustrated at program step &lt;140&gt;.
 Industrial Applicability
 The present method for determining a loading condition on a powertrain of a
 machine resulting from a loading condition on an implement thereof
 provides a backward-solved approach that substantially simplifies the
 model development process as compared to the more traditional
 forward-solved approaches. This backward-solved approach can be utilized
 during the entire work cycle and is optimally utilized during the digging
 portion of the work cycle with traditional forward-solved techniques
 utilized for the remainder of the work cycle. It is notable that the
 present method is based solely on a predetermined knowledge of empirical
 or analytical loading parameters such as forces and accelerations acting
 on the implement, and simple information such as implement dimensions,
 wheel radii, linkage dimensions, gear ratios, and the like, without
 additional information regarding operator control inputs. Thus, the
 present method provides a simpler, easier to use modeling technique that
 can be used by a larger community of designers and analysts with a
 software program that is faster than typical simulation and general
 integrator model programs. Further, since operator commands are not a
 required input, the extended and cumbersome iterations associated with the
 forward-solved approaches are not required.
 Other aspects, objects and advantages of the present invention can be
 obtained from a study of the drawings, the disclosure and the appended
 claims.