Abstract:
A signal processing method of a baler system includes the steps of receiving a signal, determining a steady state level and relating the steady state level to a characteristic of a forming bale. A signal is received from at least one sensor associated with a bale chamber of the baler system and a steady state level is determined from the signal. The steady state level of the signal is related to a characteristic of the forming bale in the bale chamber.

Description:
[0001]    This application is the US National Stage filing of International Application Serial No. PCT/EP2014/061466 filed on Jun. 3, 2014 which claims priority to Belgian Application BE2013/0389 filed Jun. 3, 2013, each of which is incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a signal processing method of an agricultural baler, and, more particularly, to a signal processing method of a load measured in the bale chamber of an agricultural baler. 
       DESCRIPTION OF THE RELATED ART 
       [0003]    Agricultural balers are used to consolidate and package crop material so as to facilitate the storage and handling of the crop material for later use. In the case of hay, a mower-conditioner is typically used to cut and condition the crop material for windrow drying in the sun. In the case of straw, an agricultural combine discharges non-grain crop material from the rear of the combine defining the straw (such as wheat or oat straw) which is to be picked up by the baler. The cut crop material is typically raked and dried, and a baler, such as a large square baler or round baler, straddles the windrows and travels along the windrows to pick up the crop material and form it into bales. 
         [0004]    On a large square baler, a pickup unit at the front of the baler gathers the cut and windrowed crop material from the ground. The pickup unit includes a pickup roll, and optionally may include other components such as side shields, stub augers, wind guard, etc. 
         [0005]    A packer unit is used to move the crop material from the pickup unit to a duct or pre-compression chamber. The packer unit forms a wad of crop within the pre-compression chamber which is then transferred to a main bale chamber. (for purposes of discussion, the charge of crop material within the pre-compression chamber will be termed a “wad”, and the charge of crop material after being compressed within the main bale chamber will be termed a “flake”). Typically such a packer unit includes packer tines or forks to move the crop material from the pickup unit into the pre-compression chamber. Instead of a packer unit it is also known to use a rotor cutter unit which may chop the crop material into smaller pieces. 
         [0006]    A stuffer unit transfers the wad of crop material in charges from the pre-compression chamber to the main bale chamber. Typically such a stuffer unit includes stuffer forks which are used to move the wad of crop material from the pre-compression chamber to the main bale chamber, in sequence with the reciprocating action of a plunger within the main bale chamber. 
         [0007]    In the main bale chamber, after the wad is injected into the bale chamber, the plunger compresses the wad of crop material into a flake against previously formed flakes to form a bale and, at the same time, gradually advances the bale toward the outlet of the bale chamber. Pressure exerted by the walls of the bale chamber dictates the frictional force required to overcome static friction and shift the flakes in the chamber. An increased force to shift the flakes causes the plunger to compact the flakes tighter, to thereby produce a higher density bale. 
         [0008]    The bale chamber typically has three moving walls (the top and two sides), which may be positioned by two hydraulically controlled actuators connected to a cam mechanism. When enough flakes have been added and the bale reaches a full (or other predetermined) size, a number of knotters are actuated which wrap and tie twine, cord or the like around the bale while it is still in the main bale chamber. The twine is cut and the formed baled is ejected out the back of the baler as a new bale is formed. 
         [0009]    As the bale is being formed a sensor associated with the drive train of the plunger is used to determine the loads encountered by the plunger to estimate the density of the bale. Such a baler is shown in e.g. U.S. Pat. No. 4,624,180 or in EP 0.346.586. This approach has limited precision for many reasons, for example, due to tolerance in the alignment of the gearbox driving the plunger and the losses in the drive train. Another reason is that the varying size of the wads can alter the information from such a sensor. In U.S. Pat. No. 6,026,741 a baler is shown where the main information is still received from a sensor which is installed on the gearbox of the baler. Although a second sensor is arranged in the bale chamber, the second sensor will only be able to detect when a fresh amount of crop material is in the bale chamber. During the duration of this signal, the signal from the first sensor on the gearbox will be used to determine the force applied on the charge of fresh crop material during compression thereof. However, the same problems as discussed earlier still remain, since the sensor signal used to determine the force is still allocated to the gearbox. 
         [0010]    What is needed in the art is a method to process a signal from sensors which will accurately determine the density of the forage material in the bale chamber and to additionally determine the load on the plunger, and to adjust the bale density while the bale is in the bale chamber. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention provides a method of processing a signal received from sensors placed on the bale chamber and uses the information from the sensors, that detect the deflection of the structural members of the bale chamber, to determine the plunger load and the density of the forming bale. 
         [0012]    The invention in one form is directed to a signal processing method of a baler system, the method including the steps of receiving a signal, determining a steady state level and relating the steady state level to a characteristic of a forming bale. The “receiving a signal” step receives a signal from at least one sensor associated with a bale chamber of the baler system. The “determining a steady state level” step determines the steady state level from the signal. The “relating the steady state level to a characteristic of a forming bale” step relates the steady state level of the signal to a characteristic of the forming bale in the bale chamber. 
         [0013]    The invention in yet another form is directed to a signal processing method of a baler system, the method including the steps of: receiving a signal from at least one sensor coupled to a structural member of a bale chamber of the baler system; determining a steady state level from the signal and/or a peak value from the signal; and relating either the steady state level to a characteristic of forming bale in the bale chamber or the peak value to a parameter of a plunger in the baler system. 
         [0014]    The present invention advantageously estimates the plunger load value and/or the bale density value from a single type of measurement associated with the deflection of components of the bale chamber as detected by the sensors. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein: 
           [0016]      FIG. 1  is a perspective cutaway view showing the internal workings of a large square baler having a bale chamber with a sensor used by an embodiment of a method of the present invention; 
           [0017]      FIG. 2  is a partially exploded view illustrating the bale chamber of  FIG. 1 ; 
           [0018]      FIG. 3  is a schematical view of a structural member of the bale chamber of  FIGS. 1 and 2 , illustrating the use of the sensor of the present invention; 
           [0019]      FIG. 4  is a schematical view of an embodiment of a control system of the present invention used in the baler system illustrated in  FIGS. 1-3 ; and 
           [0020]      FIG. 5  is a flowchart illustrating an embodiment of a method for processing a signal from a bale chamber sensor of the baler system of  FIGS. 1-4 . 
       
    
    
       [0021]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate an embodiment of the invention in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    Referring now to the drawings, and more particularly to  FIG. 1 , there is shown an agricultural harvester in the form of a large square baler  10 .  FIG. 1  is a perspective cutaway view showing the internal workings of a large square baler  10 . In the specific embodiment shown, the baler  10  is a New Holland BB960 which is manufactured and sold by the assignee of the present invention. 
         [0023]    The baler  10  operates on a two stage feeding system. Crop material is lifted from windrows into the baler  10  using a pickup unit  12 . The pickup unit  12  includes a rotating pickup roll  14  with tines  16  which move the crop rearward toward a packer unit  18 . An optional pair of stub augers (one of which is shown, but not numbered) are positioned above the pickup roll  14  to move the crop material laterally inward. The packer unit  18  includes packer tines  20  which push the crop into a pre-compression chamber  22  to form a wad of crop material. The packer tines  20  intertwine the crop together and pack the crop within pre-compression chamber  22 . The pre-compression chamber  22  and the packer tines  20  function as the first stage for crop compression. Once the pressure in the pre-compression chamber  22  reaches a predetermined sensed value, a stuffer unit  24  moves the wad of crop from the pre-compression chamber  22  to a bale chamber  26 . The Stuffer unit  24  includes stuffer forks  28  which thrust the wad of crop directly in front of a plunger  30 , which reciprocates within the bale chamber  26  and compresses the wad of crop into a flake. The stuffer forks  28  return to their original stationary state after the wad of material has been moved into the bale chamber  26 . The plunger  30  compresses the wads of crop into flakes to form a bale and, at the same time, gradually advances the bale toward an outlet  32  of the bale chamber  26 . The bale chamber  26  and plunger  30  function as the second stage for crop compression. When enough flakes have been added and the bale reaches a full (or other predetermined) size, the knotters  34  are actuated which wrap and tie twine around the bale while it is still in the bale chamber  26 . Needles  36  bring the lower twine up to the knotters  34  and the tying process then takes place. The twine is cut and the formed baled is ejected from a discharge chute  38  as a new bale is formed. 
         [0024]    Referring now to  FIG. 2  some framework of the baler system  10  is revealed with the bale chamber  26  illustrated in an exploded view to better illustrate the placement of sensors  40  relative to bale chamber  26 . Bale chamber  26  is defined by a floor  42 , a ceiling  44  and walls  46  and  48 . For purposes of discussion floor  42  will be considered fixed relative to the framework and the ceiling  44  and the walls  46  and  48  are movable by the action of a density ring actuator system  50 . The bale chamber  26  has a cross-section that is variable as determined by the density ring actuator system  50 . The ceiling  44  and the walls  46  and  48  are shown in  FIG. 2  as being expanded out creating an outward taper allowing a bale to easily pass through the bale chamber  26 . Under normal use the bale chamber  26  is positioned by the density ring actuator system  50  to be tapered inwardly leading to a reduced cross section as the bale moves through the bale chamber  26 . The control of the cross section of the bale chamber  26  leads directly to the control of the density of the bale that is formed in the bale chamber  26 , since a more inwardly tapered configuration increases the restriction of travel of the bale. 
         [0025]    The floor  42 , ceiling  44  and walls  46  and  48  each have at least one structural member  52  extending along a bale forming direction  70 . The structural members  52  are what contain the bale and serve to restrict the movement of the bale as it travels through the bale chamber  26 . The plunger  30 , also referred to as a compressing device  30  is not shown in  FIG. 2  for the purpose of clarity. The plunger  30  pushes the wad against the previously formed flakes causing a movement of the forming bale in the bale forming direction  70 . This compression of the crop material in the bale is a force that is conveyed by way of the forming bale to the structural members  52 . When the plunger  30  retracts there is some rebound of portions of the bale and the now reduced force on the bale is also felt by the structural members  52 . 
         [0026]    The sensors  40  are positioned on selected structural members  52  to detect an amount of force being conveyed to the structural members  52 . This detected force contains information relative to both the load on the plunger  30  as it is compressing the crop material as well as the density of the forming bale. The structural members  52  are held by support members, here illustrated as the support members  54  and  60  holding the structural members  52  associated with the ceiling  44  and the support members  56  and  58  holding the structural members  52  associated with the wall  48 . In a like manner the structural members  52  associated with the wall  46  are also constrained. The sensors  40  are shown as being located on the structural members  52  proximate to the midpoint between the respective support members  54 ,  56 ,  58  and  60 . The sensors  40  are also shown in a plane normal to the bale forming direction  70 , although other positions are also contemplated. It is further contemplated that multiple sensors can be placed along the bale chamber  26  to get further information. For example, the supports of the floor  42  are closer together and the sensors are positioned midway between the crossbeams to get maximal effect. 
         [0027]    Now, additionally referring to  FIG. 3  there is illustrated, in a schematical form, the support members  56  and  58  with the structural member  52  extending therebetween and therebeyond. The dashed line illustrates a flexure of the structural member  52 , with the sensor  40  being coupled thereto, so as to detect the flexure of the structural member  52  between support members  56  and  58 , as the pressure  72  (illustrated by an arrow  72 ) of the forming bale against the structural member  52  is applied. As the pressure  72  varies the sensor  40  detects the variation of the flexure of the structural member  52  and creates a signal representative of the varying pressure. The information includes a pulsed or variable portion and a slowly varying or steady state portion. The pulsed or variable portion is attributed to the periodic force imparted by the plunger  30  to the forming bale and the steady state portion is attributed to a density of the forming bale. The information is interpreted and acted upon to control the density of the bale formed in the bale chamber  26 . The density spoken of here is a relative density. The density is relative since the crop material itself has compressibility characteristics, frictional characteristics as it slides in the bale chamber  26 , inherent weight and moisture content, all of which change as the composition of the crop material changes. 
         [0028]    The support member  60  is a pivotal connection  62  between the framework of the baler  10  and the structural members  52  that are associated with the ceiling  44 . In a similar fashion, the structural members  52  associated with the walls  46  and  48  are pivotally connected to the framework of the baler  10 . The structural members  52  of the floor  42  are not pivotally connected to the framework. Regardless, the principle illustrated in  FIG. 3  is applicable to all of the structural members  52 . 
         [0029]    The sensors  40  may be considered to be an array of sensors with the information coming from them producing a three dimensional density distribution as the bale travels in the bale formation direction  70 . The sensors  40  may all be identical or it is also contemplated that a variety of sensor types may be utilized. The sensors  40  may take the form of a displacement sensor, a deflection sensor or a strain sensor. A displacement sensor refers to a sensor that detects the displacement of the structural member  52  as it flexes. A deflection sensor refers to a sensor that detects angular movement or the deflection of the structural member  52  as it flexes. A strain sensor refers to a sensor that detects the strain in the structural member  52  as it flexes. The sensors  40  produce the signal reflective of the varying pressure on the structural member  52 . 
         [0030]    Now, additionally referring to  FIG. 4  there is illustrated, in a schematical form, a control system  64  having a controller  66  and an operator interface  68 . The controller  66  receives signals from sensors  40 , with the signals containing the information discussed herein. The information is processed and scaled to reflect the load on the plunger  30  and/or the density of the bale in the bale chamber  26 . The controller  66  is in control of the density ring actuator  50  to thereby change the positioning of structural members  52  and thence the density of the bales produced in bale chamber  26 . The operator interface  68  receives and displays information from the controller  66  as well as conveys instructions from an operator to the controller  66 . The information displayed may include the load on the plunger  30  and/or the density of the bale in the bale chamber  26 . The controller  66  is configured to adjust the positioning of the structural members  52  to thereby alter the load on the plunger  30  and/or the density of the bales being formed. 
         [0031]    Now, additionally referring to  FIG. 5  there is shown a flowchart illustrating an embodiment of a method  100  for the processing of a signal from a bale chamber sensor. The baling chamber  26  deformation signal from the sensors  40  is received by the controller  66  at step  102 . The controller  66  segregates peak value information and steady state information from the signal at step  104  using filtering techniques. The peak value information, referred to as a peak value, is used, at step  106 , to estimate the load being experienced by plunger  30 , referred to hereafter as the estimated plunger load. The steady state information is used, at step  108 , to estimate the density of the forming bale in the bale chamber  26 , or at least the pressure under which the forming bale is being compressed in the bale chamber  26 , hereafter referred to as an estimated bale density. 
         [0032]    A target plunger load value, which may be predefined or input by an operator by way of the operator interface  68  is used as the target value, and at step  110  a delta plunger load is arrived by subtracting the target plunger load value from the estimated plunger load. It is also contemplated that instead of using a target plunger load value that a 15 maximum plunger load value may be used by controller  66  to protect the plunger  30  from be overly stressed by altering the density ring pressure and/or alerting the operator. In addition, or instead of, step  110 , a delta bale density value is arrived at by subtracting a target bale density value from the estimated bale density. The target bale density having been supplied to the controller  66  by way of the operator interface  68 . A tolerance or acceptable value of the absolute value of the delta plunger load value and/or the delta bale density value is evaluated at step  114  and if the delta values are within the acceptable tolerance, then method  100  returns to step  102 . If either of the delta values are outside of the tolerance then the method  100  proceeds to step  116 , where density ring actuator  50  is altered to thereby change the effective cross section of bale chamber  26  to alter the resistance to movement of the bale in the bale forming direction  70 . If either the plunger load value or the bale density value are too high then the cross section of the bale chamber  26  is made larger, by a predetermined amount, to thereby lower the plunger load value and/or the bale density value. In a like manner if either the plunger load value or the bale density value are too low then the cross section of the bale chamber  26  is made smaller, by a predetermined amount, to thereby lower the plunger load value and/or the bale density value. A predetermined travel distance of the bale may be used before another adjustment of the density ring actuator  50  is undertaken. The estimated plunger load value and the estimated bale density value is displayed on the operator interface  68  by action of the controller  66 . 
         [0033]    It is also contemplated that information such as the pressure reflected in the hydraulic fluid of the actuators of density ring actuator  50 , as a result of the outward pressure of the forming bale, can be used to provide the signal used at step  102 . Additionally, the known selected cross-sectional area that is set by the position of the density ring actuator  50  can be used in the bale density calculation process. It is further contemplated to use a weighing system, located at the back of the baler  10 , to obtain the weight of the complete bale and to thereby get an absolute density of the bale. This information is then used by the controller  66  in conjunction with the method  100  to control the absolute density of the formed bales. 
         [0034]    Advantageously the present invention estimates the plunger load value and/or the bale density value from a single type of measurement associated with the deflection of components of the bale chamber  26  as detected by the sensors  40 . 
         [0035]    While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.