Abstract:
A method of harvesting a stalk-based plant (P), such as sugarcane, includes generating at least one laser beam (b) and causing the at least one laser beam (b) to at least momentarily come into contact with the sugarcane stalk (P). This severs the stalk (P) and cauterizes the stalk (P) where severed.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to a method of harvesting sugarcane and a combine that is useful for harvesting sugarcane. Although the invention is especially useful for harvesting sugarcane, it may be used to harvest other food-producing plants, such as corn, or as a bush hog to clear fields of stalk-like growth. 
     Sugarcane has been harvested manually until recently. As available labor decreases in supply, mechanical combines, or harvesters, have been introduced to automate the harvesting process. The known mechanical combines utilize knives supported by a vehicle which is propelled by caterpillars or treads. The mechanical combine cuts the entire stalk close to the ground and cuts the stalk into lengths of approximately 18 inches or more and ships the stalks to a processing plant. The processing plant removes the foliage which is shipped back to the field for reintroduction to the soil as fertilizer. 
     Such known mechanical combines have numerous disadvantages. Because the stalk tends to weep at the cut, it is necessary to maintain the length of the stalk as long as possible in order to avoid excessive loss of glucose. Also, bacteria in soil tend to enter the stalk at the cut and cause a process within the stalk that tends to reduce sugar production. This necessitates rapid processing of the cane before the bacteria-based process further reduces yield. 
     Another difficulty with existing harvesting techniques is the burning of the foliage. This is done to expose the base of the stalk to allow the combine operator to view the stalk/soil interface, as well as to dispose of the foliage. The burning of foliage has become a health hazard not only to the farm workers and local residents, but also to vehicles traveling local highways that may have difficulty seeing because of the smoke density. This has led to an outlawing of burning in some areas where sugarcane is grown. 
     Additionally, handling of the foliage waste is a significant cost of the process. The foliage waste must be physically removed from the stalk at the processing plant and shipped back to the field for reintroduction to the soil. All of this adds cost to the process. Indeed, it is estimated that up to 75 percent of the hauling cost associated with harvesting sugarcane with a mechanical combine is in handling the foliage. 
     SUMMARY OF THE INVENTION 
     The present invention provides a method of harvesting sugarcane in a manner that reduces difficulties created by traditional mechanical harvesting of sugarcane stalks. In particular, the present invention significantly reduces the loss of glucose from the weeping at the harvesting cut. It also significantly reduces the entrance of bacteria at the cut, thereby increasing sugar yield. Moreover, because the present invention reduces weeping and bacteria contamination, it allows the stalk to be cut into smaller sections. This allows the bulk of the foliage to be removed as part of the harvesting process because the foliage naturally is removed from a stalk cut into small sections. 
     A method of harvesting sugarcane having a stalk, according to an aspect of the invention, includes generating at least one laser beam and causing at least one laser beam to at least momentarily come into contact with the sugarcane thereby severing the stalk and substantially cauterizing the stalk where severed. Among the many advantages that are provided, this substantially reduces loss of glucose and contamination of the glucose with bacteria from the soil. 
     The laser beam may be scanned across the sugarcane stalk, such as approximately a diameter of a sugarcane&#39;s stalk. The sugarcane may be cut into a plurality of sections. A fluid may be flowed past the sections to remove foliage waste. The sections may be tumbled to assist in removing the foliage waste. The sugarcane stalk may be cut into a plurality of sections that are less than one foot in length and may be less than one-half of a foot in length. 
     The at least one laser beam may be focused at a distance of less than one foot and may be focused at a distance of four inches or less. The distance of the at least one laser beam from the ground may be controlled, such as by sensing the ground with a non-contact sensor. A non-contact sensor may be a laser sensor, an ultrasonic sensor, and/or a radar sensor. 
     The at least one laser beam may be generated by a laser beam source. The laser beam source may be supported with a vehicle having pneumatic tires. The laser beam source may be supported with a vehicle having an electrical generator for powering the at least one laser source. 
     An agricultural combine apparatus, or harvester, according to another aspect of the invention, may include at least one laser projecting a laser beam and a support. The support supports the at least one laser to position the beam to intersect a stalk of a plant. 
     These and other objects, advantages and features of this invention will become apparent upon review of the following specification in conjunction with the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevation of a combine and a method of harvesting a plant having a stalk, according to the invention; 
     FIG. 2 is a top plan view of the combine and method in FIG. 1; 
     FIG. 3 illustrates the cuts applied to the sugarcane, according to the invention; 
     FIG. 4 illustrates a cross-section of a sugarcane cut, according to the prior art; and 
     FIG. 5 illustrates a cross-section of a sugarcane cauterized, according to the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now specifically to the drawings, and the illustrative embodiments depicted therein, a combine or harvester  10 , according to the invention, includes a laser assembly  11  having at least one laser source  12  projecting a laser in the nature of a beam of photons “b” positioned to intersect the stalk of a plant “p” (FIGS.  1  and  2 ). Laser assembly  11  is supported by a vehicle  14 . Vehicle  14  may be a conventional harvester of the type disclosed in U.S. Pat. No. 4,408,441, the disclosure of which is hereby incorporated herein by reference. As such, laser assembly  14  may be a retrofit kit to replace the mechanical cutters of the harvester while utilizing the propulsion system and gathering arms of the combine. Alternatively, laser assembly  11  may be supported by a vehicle  14  having pneumatic tires  18  and a lightweight frame to reduce compaction of the soil. Wheels  18  may be mounted with hydraulic lifts (not shown) and a control to keep the body of vehicle  14  level, notwithstanding variation in terrain. Pneumatic tires  18  are less likely to loosen the upper surface of the soil. Moreover, support  14  has a weight that is significantly less than that of mechanical combines. Accordingly, the tendency for tires  18  to compact the soil is significantly reduced over mechanical combines. A generator  16 , which may be supported by vehicle  14 , is provided to supply electrical energy to power laser assembly  11 . 
     Preferably, assembly  11  is a plurality of lasers  12  laterally arranged in a laser, as illustrated in FIG.  2 . Most preferably, the plurality of lasers is moved, such as by scanning, or the like, laterally from the solid line position illustrated in FIG. 2 to the phantom position illustrated in FIG.  2 . This allows a fewer number of lasers to be utilized to cut the stalks of plants “p.” In the illustrated embodiment, lasers  12  cover a cutting distance “d” laterally of the movement of support  14 . Preferably, distance “d” is on the order of one foot and is, most preferably, in the range of 12 inches to 14 inches. Generator  16  is sized to supply the power requirements of lasers  12 . By way of example, if eight laser assemblies are utilized, and each require 1 kilowatt of power, then generator  16  would be at least 8 kilowatts in size. In the illustrated embodiment, support  14  scans lasers  12  at a rate of on the order of one cycle per second. However, other rates may be appropriate for the application. The lasers  12  may be moved by a purely lateral motion, as illustrated in FIG.  2 . Alternatively, they can be swept in a fan shape motion as would be suggested to the skilled artisan. 
     Laser  12  has a focal length that is less than one foot in length, and may be less than one-half of a foot in length, and may be four inches or less. This reduces the necessity for shielding around lasers  12  to protect individuals in the area in which combine  10  is operating from damage resulting from contact with beam “b,” such as by the beam contacting the eyes of the individual. It is advantageous to reduce the necessity for any special shielding around laser  12  because such shield may reduce the effectiveness of its operation in cutting the stalks of plants “p.” 
     An advantage of combine  10  is that it cauterizes the stalk, as seen in FIG. 5, in which the surface of the cut is relatively uniform and exposes channels in the stalk. This is an advantage over the cut produced by mechanical cutting of the stalk, as illustrated in FIG. 4, in which glucose may ooze from the many exposed channels CH in the cut thereby reducing the yield of sugar. Advantageously, by cauterizing the cut, the present invention facilitates the cutting of the stalk into multiple short pieces, or segments, S, as illustrated in FIG. 3, by a series of cuts C to each stalk P. Combine  10  may cut the sugarcane into lengths of less than one foot, less than one-half of a foot, and even as low as approximately four inches or less without concern from glucose weeping from each cut C. As seen in FIG. 3, the producing of multiple short pieces of stalk results in a cutting of the foliage F thereby cutting excess lengths of foliage F from the stalk. This allows the foliage to be removed at the site, such as by tumbling the stack while passing the stalk and foliage through a fluid jet, such as a jet of compressed air. An example of an apparatus that may discharge the separated excess foliage is as disclosed in U.S. Pat. No. 5,092,110, the disclosure of which is hereby incorporated herein by reference. This separates the foliage from the stalk such that the foliage may be immediately returned to the soil without being hauled to and from the processing plant. This reduces the cost of processing the foliage. Furthermore, the stalk can be more quickly processed without the necessity for a separate stalk-removing procedure at the processing plant. This further increases the yield of sugar because of the initiation of conversion of glucose to sugar begins as soon as the plant is cut. In the illustrated embodiment, combine  10  initially cuts the stalk close to the ground with the remaining cuts that divide the stalk into small pieces being performed when the stalk is supported by support  14 . 
     In order to control the height of the initial cut “c,” a height control mechanism  20  may be provided to control the height of laser assembly  11 . Height control mechanism  20  is a non-contact sensor that senses distance to the soil and a control that adjusts to that level selected by an operator. Height control mechanism  20  may be a laser-based control, a camera-based control, an ultrasonic-based control, a radar-based control, a mechanical sensor, or the like, which are known in the art. By way of example, such height control mechanism may be of the type disclosed in U.S. Pat. No. 5,327,345, the disclosure of which is hereby incorporated herein by reference. Because height control mechanism  20  is capable of guiding position of laser assembly  1  without constant intervention by an operator, it is no longer necessary to burn the foliage around plants to allow an operator to view the interface between the soil and the sugarcane. This avoids the problems created by burning in the past. 
     Another laser assembly (not shown) may be supported by vehicle  14  in a position to cut off tops of the sugarcane stalks. This additional laser assembly may be manually controlled in vertical height by an operator, which is feasible because sugarcane stalk tops are somewhat consistent in height. However, a height control similar to mechanism  20  could also be used to control a laser assembly to cut sugarcane stalk tops. 
     Thus, it is seen that the present invention provides a unique combine and method of harvesting a plant having a stalk, which is more efficient at processing the stalks, as set forth above. In addition to facilitating the removal of foliage at the site, wherein the foliage can be immediately returned to the soil, the present invention produces less soil compaction and less disturbing of the top layer of the soil. This reduces the need for subsequent aeration of the soil and the likelihood that the trucks hauling the sugarcane to the processing plant will transfer loose soil from the field to the road. Furthermore, the necessity for hauling only the stalk, and not the foliage, to the processing plant reduces the number of loads that must be hauled for each unit of output. Furthermore, the need to burn foliage is advantageously removed. 
     The present invention makes use of commercially available lasers, which are capable of having their photon beam focused in response to an output from a control. However, the invention may also be used with a laser whose photon beam is permanently focused at a focal length “f” selected in the manner set forth above. 
     Although the invention is most advantageous in harvesting sugarcane, its use in other stalk-based crops, such as corn, will be apparent to those skilled in the art. Furthermore, as set forth above, the invention may be applied to other uses, such as a bush hog, or the like. 
     Changes and modifications in the specifically described embodiments can be carried out without departing from the principles of the invention, which is intended to be, limited only by the scope of the appended claims, as interpreted according to the principles of patent law including the doctrine of equivalents.