Abstract:
Apparatus and a method for monitoring the performance of control algorithms, and inappropriate operator actions, and for providing failsafe deceleration for a vehicle, particularly an agricultural windrower, wherein the propulsion driveline of the vehicle is controllably and actively decelerated. Inappropriate operator actions can include, but are not limited to, attempted engagement of the park brake when operating in a high speed range. Control algorithm fault conditions can include, for instance, input commands changing at a rate beyond a predetermined threshold, and mismatch between operator control devices such as a FNR lever and a neutral switch.

Description:
[0001]     This application claims the benefit of U.S. Provisional Application Nos. 60/699,943 and 60/700,050, filed Jul. 16, 2005. 
     
    
     TECHNICAL FIELD  
       [0002]     The present invention relates to vehicular safeing and, more particularly, to apparatus and a method providing failsafe deceleration for an agricultural windrower.  
       BACKGROUND OF THE INVENTION  
       [0003]     U.S. Provisional Application Nos. 60/699,943 and 60/700,050, filed Jul. 16, 2005, are incorporated herein in their entirety by reference. U.S. Pat. No. 6,901,729 is also incorporated herein in its entirety by reference.  
         [0004]     Vehicles, such as, but not limited to, agricultural windrowers, can utilize control algorithms for translating input signals, for instance, from operator controlled input devices such as a forward-neutral-reverse (FNR) lever, also sometimes referred to as a multi-function-handle (MFH), to systems to be controlled thereby, such as the propulsion driveline.  
         [0005]     It is therefore desirable to have a capability to monitor the performance of such control algorithms, to ensure that the input commands are being accurately and safely translated into machine operations and movements. It is also desirable to have the capability to determine or sense when a controlled system, such as a propulsion driveline, is no longer tracking a reference input signal sufficiently well. A degradation in the tracking capability can occur for any of several reasons, such as an interrupted or corrupted communication path, such as due to electrical noise and/or damage to a conductive path such as a wiring harness, physical wear or damage, and the like. It is also desirable to have the ability to determine or sense when the controlled system is overshooting or undershooting a system bounds. For instance, a propulsion system may drive a vehicle such as a windrower at a speed greater than a set speed. A system can overshoot (measured system output exceeds the desired output value) or undershoot (measured system output is less than the desired output value), which may indicate that a controller for the output has become unstable.  
         [0006]     Still further, at times, an operator may attempt to operate the vehicle in an inappropriate manner, such as by attempting to engage or set the park brake at an inappropriate time, such as when the vehicle is moving at a high speed or within a high-speed range.  
         [0007]     When a problem or fault, such as any of the above, or an inappropriate operator action, is detected it is further desirable to have a failsafe method for bringing the vehicle to a halt, such as by actively de-stroking the propulsion system.  
       SUMMARY OF THE DISCLOSURE  
       [0008]     Accordingly, what is disclosed is apparatus and a method for monitoring the performance of control algorithms, and inappropriate operator actions, and for providing failsafe deceleration for a vehicle, particularly an agricultural windrower.  
         [0009]     A purpose of the invention is to sense when a controlled system, particularly the propulsion driveline, is subject to a fault condition, such as, but not limited to, no longer tracking a reference input signal sufficiently well, and to responsively automatically provide failsafe deceleration. Causes for this can be instability of the control system or a degradation in performance. Another purpose of the invention used to provide automatic failsafe deceleration responsive to an inappropriate operator action, such as an attempt to engage the park brake when moving at high speed, as illustrated above. Failsafe deceleration according to the invention will include actively controlling the propulsion driveline to go from a propulsion mode to a neutral mode, in a controlled manner.  
         [0010]     According to a preferred aspect of the invention, an exponentially decaying integrator is used to monitor tracking errors between propulsion commands inputted utilizing the FNR lever, and execution of the commands by the propulsion driveline. Rates of change of FNR lever command signals outside of a preset range, and FNR neutral switch faults, are also monitored.  
         [0011]     Tracking errors are integrated and then multiplied by a time-dependent exponentially decaying function. This gives the algorithm a forgetting type property. That is, the most recent error signals are weighted more heavily than ones further in the past. A threshold can be set on this exponentially decaying integrator to indicate when the controlled system is no longer tracking sufficiently well. When the value of the exponentially decaying integrator exceeds the threshold, appropriate action, namely, active de-stroking of the propulsion driveline to bring it to a neutral condition, is performed to preserve the integrity and safety of the system.  
         [0012]     According to another preferred aspect of the invention, another algorithm for monitoring the controller stability, checks bounds. When the system is overshooting (measured system output exceeds the desired output value) or undershooting (measured system output is less than the desired output value) it is checked to make sure that the measured output value isn&#39;t at a corresponding saturation limit of the hardware, which would be an indication that the controller has become unstable.  
         [0013]     The algorithms of the invention have applicability for the current control and position control loops of a propulsion system of an agricultural windrower. More particularly, in the design and operation of a windrower, and in all other similar equipment, it is important to consider the safety of the operator. Accordingly, the instant invention monitors the position of the propulsion cylinder (a cylinder and spring assembly) of the propulsion driveline relative to the FNR lever position. If there is a fault, the spring is allowed to take the drive shaft or propulsion rod of the propulsion driveline, to which pintel arms movable for stroking and de-stroking hydraulic pumps of the driveline are connected, to neutral, and the park brake is allowed to be applied.  
         [0014]     Also, two potentiometers can be affixed or mounted in connection with the Propulsion Cylinder and positioned so that at all times the combined voltage output will equal a predetermined value, here, which is 5 V. If not, it is determined that one of the potentiometers is malfunctioning and requires replacement (dual Hall tracking). The fault detection system can use electrical current error integration, position error integration, and dv/dt thresholding of the FNR and Propulsion Cylinder to identify/evaluate any faults. Additionally, the system can determine if the propulsion cylinder is stuck at either of its extents.  
         [0015]     The following formulae are preferably used for integration of current and positional errors: 
 
propulsion cylinder integrator=∫e a(T-t) *(position error)dT, with limits of integration 0 to t. 
 
electrical current integrator=∫e a(T-t) *(current error)dT, with limits of integration 0 to t. 
 
 The integrals are approximated (using integer math) via the following formula in discrete time: integral(k)=error(k)+[A*integral(k−1)] where, k is the sample time, and 0&lt;A&lt;1=decay rate. 
 
         [0016]     According to another aspect of the invention, the control module can be programmed such that the FNR dv/dt monitoring and fault detection only reacts to faults that would cause rapid acceleration, therefore ignoring rapid deceleration commands. The logic of this is that it is not desirable to prevent the machine from decelerating. However, the control module is programmed such that Propulsion Cylinder dv/dt monitoring reacts to acceleration and deceleration.  
         [0017]     As another aspect of the invention, the control module can be programmed such that if the FNR lever is in forward range, and being moved towards neutral, and if the Propulsion Cylinder is lagging behind the commanded position by more than a predetermined threshold, and the driveline is in high range, then a fault condition is determined, e.g., if the machine is sluggish to respond to an operator deceleration command, then the propulsion driveline is actively de-stroked in a controlled manner, to bring the vehicle to zero ground speed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     The advantages of this invention will be apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein:  
         [0019]      FIG. 1  is a partial side elevational view of a windrower of the type with which the invention may be used, including a header for severing crops from a field, mounted on a front end of the windrower;  
         [0020]      FIG. 2  is a simplified diagrammatic representation of a propulsion driveline of the windrower incorporating aspects of the instant invention;  
         [0021]      FIG. 3  is a schematic of aspects of circuitry of the propulsion driveline;  
         [0022]      FIG. 4  is another schematic of aspects of circuitry of the propulsion driveline;  
         [0023]      FIG. 5  is another schematic of circuitry of the propulsion driveline;  
         [0024]      FIG. 6  is still another schematic of aspects of circuitry of the propulsion driveline;  
         [0025]      FIG. 7  is a diagram illustrating a control system of the propulsion driveline and fault detection system embodying a preferred method of the instant invention;  
         [0026]      FIG. 8  is a flow diagram illustrating steps including aspects of the invention;  
         [0027]      FIG. 9  is a flow diagram illustrating steps including other aspects of the invention;  
         [0028]      FIG. 10  is a flow diagram illustrating steps including still other aspects of the invention;  
         [0029]      FIG. 11  is a listing of code of a computer program incorporating steps of a preferred embodiment of the method of the invention;  
         [0030]      FIG. 12  is a continuation of the listing;  
         [0031]      FIG. 13  is a continuation of the listing;  
         [0032]      FIG. 14  is a continuation of the listing;  
         [0033]      FIG. 15  is a continuation of the listing;  
         [0034]      FIG. 16  is a continuation of the listing;  
         [0035]      FIG. 17  is a continuation of the listing;  
         [0036]      FIG. 18  is a continuation of the listing;  
         [0037]      FIG. 19  is a continuation of the listing;  
         [0038]      FIG. 20  is a continuation of the listing;  
         [0039]      FIG. 21  is a continuation of the listing;  
         [0040]      FIG. 22  is a continuation of the listing;  
         [0041]      FIG. 23  is a continuation of the listing; and  
         [0042]      FIG. 24  is a continuation of the listing. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0043]     Many of the fastening, connection, processes and other means and components utilized in this invention are widely known and used in the field of the invention described, and their exact nature or type is not necessary for an understanding and use of the invention by a person skilled in the art, and they will not therefore be discussed in significant detail. Also, any reference herein to the terms “left” or “right” are used as a matter of mere convenience, and are determined by standing at the rear of the machine facing in its normal direction of travel. Furthermore, the various components shown or described herein for any specific application of this invention can be varied or altered as anticipated by this invention and the practice of a specific application of any element may already by widely known or used in the art by persons skilled in the art and each will likewise not therefore be discussed in significant detail. Still further, in this description, the terms FNR lever, multi-function handle and MFH referred to the same item, and therefore are interchangeable.  
         [0044]      FIG. 1  shows a self-propelled windrower  10  incorporating the apparatus and method of the invention; however, it will be appreciated that the principles of the present invention are not limited to a self-propelled windrower, or to any specific type of harvesting machine.  
         [0045]     In the illustrated embodiment, the self-propelled windrower  10  comprises a tractor  12  and a header  14 , the header  14  being attached to the front end of the frame  16  or chassis of the tractor  12 . The header may be of generally any suitable construction and design, and may include not only crop-harvesting (mechanisms, but also crop conditioners such as elongate rolls  15 . Such attachment of the header  14  to the frame  16  is achieved through a pair of lower arms  18  (only the left one being shown, the right being generally the same) pivoted at one end to the frame  16  and at the other end to the header  14 , as well as through a central upper link  20 .  
         [0046]     One or more cylinders, such as individual lift and flotation cylinders, or a single lift/flotation cylinder, interconnects the lower arm  18  and the frame  16  on each side of the header.  
         [0047]     Typical features and operation of a system for controlling the lift and flotation functions for a header, such as header  14  depicted herein, are disclosed in U.S. Pat. No. 6,901,729, incorporated herein by reference.  
         [0048]     Referring also to  FIGS. 2, 3 ,  4 ,  5  and  6 , windrower  10  includes a propulsion driveline  22  controllably operable using operator controls for rotatably driving a left wheel  24  and a right wheel  26  for propelling windrower  10  over a ground or other surface. Hydraulic motors (not shown) in connection with each wheel  24  and  26 , respectively, are provided with fluid under pressure by hydraulic pumps  28 , for driving the wheels. The pumps  28  can be differentially controlled for supplying different and varying amounts of pressurized fluid to the hydraulic motors, for effecting desired movements of windrower  10 , including steering movements, as effected by operation of a rotatable and longitudinally movable propulsion rod  30  in connection with pintel arms  32  and  34  movable for controlling displacement of pumps  28  in the well-known manner. Steering commands are inputted to driveline  22  by an operator via an operator control which is a steering wheel  36  disposed in an operator cab  38  of windrower  10 . Steering movements of windrower  10  are effected by rotating respective wheels  24  and  26  at different speeds. Propulsion speed and direction commands are inputted to driveline  22  by an operator via an operator control which is a FNR lever  40  also disposed in cab  38 .  
         [0049]     FNR lever  40  is configured to operate a suitable sensor or sensors operable for generating varying information or outputs representative of the position of lever  40  when lever  40  is manipulated or moved, including one rotary potentiometer  42  and a neutral switch  44 , each of which is connected to a tractor control module  46  via a suitable conductive path or paths  48 , which can be, for instance, a wire or wires of a wiring harness, an optical path, a wireless path, or the like. Tractor control module  46  can be provided as a single unit, or two or more control modules connected by a controller area network (CAN). Movements of FNR lever  40  in relation to the neutral position will cause potentiometer  42  to output a varying signal representative of the position of lever  40 , which signal comprise a voltage. It is desired for this voltage signal to very precisely indicate the position of lever  40 , such that precise control of the forward and rearward movements of windrower  10  can be achieved.  
         [0050]     Neutral switch  44  is also mounted and configured such that movements of FNR lever  40  into the neutral position, and out of the neutral position, will cause changes in the operating state of switch  44 . Here, forward and rearward movements of FNR lever  40  from a generally straight up neutral position shown, will effect a change of state of switch  44  which will be outputted to control module  46 , which will responsively power up the propulsion driveline, control module  46  controlling the propulsion speed of windrower  10  as a function of the voltage output of the potentiometer  42 . Similarly, rearward movement of FNR lever  40  from the neutral position will effect a change of state of switch  44  outputted to control module  46  to affect operation of the propulsion driveline in the reverse direction, and the voltage output of the potentiometer  42  will be used to control reverse speed. It is also desired that, when lever  40  is moved into the neutral position, the propulsion system be controlled to positively de-stroke or otherwise transition into a non-propelling state over time, such that abrupt stoppage does not occur.  
         [0051]     Other operator controls include a park brake switch  50  also connected to tractor control module  46  via a conductive path  48 , and via another conductive path  48  to a key switch  52  and a start relay  54  in connection with a starter of engine  22  and with tractor control module  46 . A 2-speed switch  56  is connected to tractor control module  46  via another conductive path  48 , as is a field cruise switch  58 .  
         [0052]     Tractor control module  46  is in connection with a dual rotary potentiometer  62  via conductive paths  48 , potentiometer  62  being operable for outputting information representative of the position of a propulsion cylinder  64 . Propulsion cylinder  64  is extendable and retractable by solenoids controlled by tractor control module  46 , based on the voltage outputs of potentiometer  42 , to move propulsion rod  30  longitudinally for changing the stroke of the hydraulic pumps  28  via the angle of the pintel arms  32  and  34 , for effecting propulsion of the windrower. A rotary potentiometer  66  is operable for outputting information representative of the position of pintel arm  32  to module  46  via another conductive path  48 , providing information representative of differential stroking of pumps  28  to effect steering movements. Information representative of speed of respective wheels  24  and  26  is determined by reluctance speed sensors ( FIG. 5 ) and communicated via conductive paths  48  to module  46 . Differences in the speed readings is also indicative of steering movements.  
         [0053]      FIGS. 3, 4 ,  5  and  6  schematically illustrate circuitry of propulsion driveline  22 , including those associated primarily with the operator controls, including potentiometer  42 ; neutral switch  44 ; control module  46 ; park brake switch  50 ; speed switch  56 ; and additionally, a park brake latch relay  70 ; a propulsion enable relay  72 , also sometimes referred to as a propulsion latching relay; and a propulsion interlock relay  74 . Other illustrated elements of propulsion driveline  22  include a park brake interlock relay  60 , a brake valve solenoid  76  and a ground speed high solenoid  78 .  
         [0054]      FIG. 5  additionally schematically illustrates other aspects of propulsion driveline  22 , including aspects of tractor control module  46  in connection with propulsion cylinder position sensors  80  and  82  which incorporate rotary potentiometers  62  ( FIG. 2 ); a pintel arm position sensor  84  incorporating rotary potentiometer  66  (also  FIG. 2 ); left and right ground speed sensors  86  and  88 ; a propulsion forward solenoid  90 ; and a propulsion reverse solenoid  92 .  
         [0055]     As noted above, the instant invention utilizes control module  46  to monitor the propulsion command inputted thereto by potentiometer  42  indicative of the position of FNR lever  40 . Essentially, the output of only one of the potentiometers  62  is required for signaling propulsion commands or inputs, but two are used (dual Hall tracking) and the voltage outputs are continually summed. If the sum does not equal a predetermined value, here 5 V, it is determined that an error in the voltage signal of one or both of the potentiometers is determined. The output of potentiometer  62  is indicative of the position of propulsion cylinder  64  of the propulsion driveline  22 . The position of propulsion cylinder  64  (and thus the output of potentiometer  62 ) should, if normally operating, correspond to or track the inputted command from potentiometer  42 , modified by a transfer function, with consideration of normal deviations such as due to hysteresis, time lag in executing the propulsion commands, and the like. dv/dt (changing voltage over time) thresholding of the FNR potentiometer is used to identify/evaluate any faults.  
         [0056]      FIG. 7  includes a diagram  94  illustrating the flow of operator input commands and hardware outputs utilized in error monitoring and fault detection according to the invention. Essentially, reference input commands r (e.g., voltage inputted through the position of FNR lever  40  by potentiometer  42 ) is matched with responsive system/hardware outputs y (e.g., voltages outputted by potentiometers  62 ) to derive tracking errors e by control modules  46  (Controller H). Tracking errors e are processed to determine any faults (Fault Detection F). This is preferably done using the following exponentially decaying integrator, also used for integration of current errors: 
 propulsion cylinder integrator=∫e a(T-t) *(position error)dT, with limits of integration 0 to t.  electrical current integrator=∫e a(T-t) *(current error)dT, with limits of integration 0 to t.  
 The integrals are approximated (using integer math) via the following formula in discrete time: integral(k)=error(k)+[A*integral(k−1)] where, k is the sample time, and 0&lt;A&lt;1=decay rate to give the algorithm a forgetting type property wherein the most recent error signals are weighted more heavily than ones further in the past. A predetermined threshold is set on this exponentially decaying integrator to indicate when the controlled system is no longer tracking sufficiently well. When the value of the exponentially decaying integrator exceeds the threshold, appropriate action is taken to preserve the integrity and safety of the system, which can include outputting of a fault signal to the operator, an automatic system shutdown, or the like. overshooting (measured system output exceeds the desired output value) or undershooting (measured system output is less than the desired output value) it is checked to make sure that the measured output value isn&#39;t at a corresponding saturation limit of the hardware, which would be an indication that the controller has become unstable. 
 
         [0057]     If there is a fault, solenoids A and B ( FIG. 2 ) controlling the valve which directs hydraulic fluid to the chambers of propulsion cylinder  64  are de-energized, to allow the spring associated with propulsion cylinder  64  to take propulsion rod  30  to neutral, thereby de-stroking hydraulic pumps  28 , and the park brake is allowed to be applied.  
         [0058]     Control module  46  can be programmed such that the FNR dv/dt monitoring and fault detection only reacts to faults that would cause rapid acceleration, therefore ignoring rapid deceleration commands. However, control module  46  can be programmed such that Propulsion Cylinder dv/dt monitoring reacts to acceleration and deceleration.  
         [0059]     Control module  46  can additionally be programmed such that if FNR lever  40  is in a forward range, that is, it is moved in the direction for commanding the windrower to move forward, and is being moved towards neutral, and if the Propulsion Cylinder  64  is lagging behind the commanded position by more than a predetermined threshold, and driveline  22  is in high range, then a fault condition is determined, e.g., if the machine is sluggish to respond to an operator deceleration command, then the propulsion driveline is actively de-stroked and park brake is automatically applied.  
         [0060]      FIGS. 8, 9  and  10  illustrate steps of the method of the instant invention for providing failsafe deceleration of a windrower, such as windrower  10 , when an operator attempts to take an inappropriate action, here, to engage the park brake with the windrower operating in the high-speed range ( FIG. 8 ); a fault condition is determined in the operation of the neutral switch ( FIG. 9 ); and a fault condition is determined with respect to operation of the FNR lever, namely, rate of change in signals thereof is out of a predetermined range ( FIG. 10 ).  
         [0061]     Referring more particularly to flow diagram  96  of  FIG. 8 , control module  46  monitors the speed range of windrower  10 , as denoted at block  98 , and park brake status, as denoted at block  100 . If the operator attempts to actuate park brake switch  50  ( FIG. 2 ), as determined at decision block  102 , control module  46  will determine if the propulsion driveline is in the high-speed range, as denoted at decision block  104 . If yes, control module  46  will automatically commence active, controlled de-stroke of pumps  28 , as denoted at block  106 . Control module  46  will then monitor the position of the propulsion cylinder using the outputs of potentiometers  62 , to determine when the propulsion cylinder is at neutral, as denoted at decision block  108 . When it is determined that the propulsion cylinder is at neutral, the park brake is applied, as denoted at block  110 .  
         [0062]     Referring more particularly to flow diagram  112  in  FIG. 9 , control module  46  monitors errors in signals from operation of neutral switch  44 , as denoted at block  114 . If, using the fault detection routine set forth above, a fault condition exists, as determined at decision block  116 , control module  46  will proceed to determine whether the propulsion cylinder is at neutral, as set forth by decision block  118 . If the propulsion cylinder is not at neutral, control module  46  will proceed to actively de-stroke pumps  28 , as denoted at block  120 , to safely bring the propulsion driveline to neutral. Control module  46  will then output a fault condition signal, as denoted at block  122 .  
         [0063]     Referring more particularly to flow diagram  124  in  FIG. 10 , control module  46  monitors errors in the FNR lever rate of change, as denoted at block  126 . It is determined that the rate of change is beyond a predetermined threshold, as determined at block  128 , control module  46  will determine if the propulsion cylinder is at neutral, as denoted at decision block  130 . If not, control module  46  will automatically control the propulsion cylinder to de-stroke pumps  28 , as denoted at block  132 , until the propulsion driveline is in neutral, and will output a fault condition signal, as denoted at block  134 .  
         [0064]     Referring also to  FIGS. 11-24 , lines of code of an actual computer program embodying the above described steps of the method of the invention is disclosed. The notes accompanying the lines of code describe many features of the method of the invention. In the code, the FNR lever is identified as the MFH.  
         [0065]     It will be understood that changes in the details, materials, steps and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the inventions. Accordingly, the following claims are intended to protect the invention broadly as well as in the specific form shown.