US20070125557A1 - Work implement side shift control and method - Google Patents

Abstract

A system for automatically moving a work implement of a work machine includes a position monitoring system configured to track a position of the work implement relative to a mapped landscape and programmable to incorporate an electronic representation of at least one entity designated to be avoided into the mapped landscape. The system also includes a controller configured to initiate movement of the work implement in response to information from the position monitoring system, including movement of the work implement to avoid the at least one entity. The work machine has a longitudinal axis aligned with a direction of travel of the work machine and the movement of the work implement includes movement of an edge of the work implement, nearest to the at least one entity, relative to a vertical plane containing the longitudinal axis.

Description

TECHNICAL FIELD
• This disclosure is directed to a system and method for controlling the movement of a work implement and, more particularly, to a system and method for controlling side shift of a work implement.
BACKGROUND
• Work machines such as motor graders, track-type tractors (e.g. bulldozers), wheeled tractors, loaders, excavators, etc. may include work implements for performing various functions. During operation, there may be entities, such as obstacles or barriers, that an operator of the work machine may wish to avoid. In some situations, it may be desirable to operate a work implement in close proximity to such entities, and in other situations, it may be desirable to simply avoid entities. In either situation, operation around entities can require considerable skill and attention on the part of a machine operator. However, even a skilled operator may be unable to avoid certain entities and achieve desired results in all situations. For example, an entity. may be in a blind spot of the operator, the operator may not be able to see the entire work implement to judge its proximity to an entity, or it may be difficult to simultneously operate the controls of the work implement with precision while operating the other functions of the machine.
• Systems have been developed for automating certain functions of a work machine in an attempt to improve efficiency and reduce the skill level required to operate a machine. For example, U.S. Pat. No. 6,655,465 (“the '465 patent”) issued to Carlson et al. on Dec. 2, 2003, describes a system and method for automatic control of a motor grader blade based on mapped information correlated to a worksite. The system of the '465 patent tracks the position of the blade as the motor grader traverses the work site landscape. This system is configured to automatically control the position of the blade based on the location of the blade with respect to the worksite. Specifically, the system of the '465 patent automatically positions the blade with respect to a reference line and prevents the blade from moving more than a certain distance away from the reference line.
• Although the system of the '465 patent may improve blade placement and reduce the level of skill needed to operate the machine, it cannot automatically avoid entities at a work site. Further, the system of the '465 patent is not configured to maintain a certain distance between a work implement and entities at a work site. For example, while the system of the '465 patent maintains the blade within a pre-set path of travel, the system does not include automated features for entity avoidance.
• The disclosed control system is directed towards overcoming one or more of the problems set forth above.
SUMMARY OF THE INVENTION
• In one aspect, the present disclosure is directed to a system for automatically moving a work implement of a work machine. The work machine may include a longitudinal axis aligned with a direction of travel of the work machine. The system may include a position monitoring system configured to track a position of the work implement relative to a mapped landscape and programmable to incorporate an electronic representation of at least one entity into the mapped landscape. The system may also include a controller configured to initiate movement of the work implement in response to information from the position monitoring system, including movement of the work implement to avoid the at least one entity. The movement of the work implement may include movement of an edge of the work implement, nearest to the at least one entity, relative to a vertical plane containing the longitudinal axis.
• In another aspect, the present disclosure is directed to a motor grader including a cab, a traction system, a power source, and a work implement having an edge. The motor grader may also include a longitudinal axis aligned with a direction of travel of the motor grader. The motor grader may further include a position monitoring system configured to track a position of the work implement relative to a mapped landscape. The position monitoring system may be programmable to incorporate an electronic representation of at least one entity designated to be avoided into the mapped landscape. The system may further include a controller configured to initiate movement of the work implement in response to information from the position monitoring system, which may include movement of the work implement to maintain a predetermined distance between the at least one entity and an edge of the work implement nearest to the entity. The movement of the work implement may include movement of the edge of the work implement relative to a vertical plane containing the longitudinal axis.
• In another aspect, the present disclosure is directed to a method of controlling a work implement for a work machine. The work machine may include a longitudinal axis aligned with a direction of travel of the work machine. The method may include determining an actual position of a work implement relative to a mapped landscape. At least one predetermined entity designated to be avoided may be located with respect to the actual position of the work implement. A distance between the at least one predetermined entity and an edge of the work implement nearest to the at least one predetermined entity may be determined and movement of the work implement may be automatically controlled in response to a comparison of the distance to a predetermined distance. The movement of the work implement may include movement of the edge of the work implement relative to a vertical plane containing the longitudinal axis in order to avoid the at least one predetermined entity.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a diagrammatic illustration of a work machine according to an exemplary disclosed embodiment;
• FIG. 2 is a diagrammatic exploded view illustration of a drawbar-circle-moldboard assembly according to an exemplary disclosed embodiment;
• FIG. 3 is a diagrammatic top view representation of a work implement blade swivel motion according to an exemplary disclosed embodiment;
• FIG. 4 is a block diagram representation of a work implement control system according to an exemplary disclosed embodiment;
• FIG. 5 is a diagrammatic top view representation of a work machine at a work site according to an exemplary disclosed embodiment; and
• FIG. 6 is a flow chart of a process for controlling side shift of a work implement according to an exemplary disclosed embodiment.
DETAILED DESCRIPTION
• FIG. 1 illustrates an exemplary embodiment of awork machine10, which includes a system for automatically moving a work implement12. Althoughwork machine10 is shown as a motor grader,work machine10 may include other types of work machines such as, for example, track-type tractors (e.g. bulldozers), wheeled tractors, loaders, excavators, and any other type of work machine.Work machine10 may include work implement12, acab14, apower source16, one ormore traction devices18, acontroller20, and positionmonitoring system components22, including one or more Global Positioning System (GPS)receivers24, aprocessor26, and amonitor display28.
• FIG. 2 depicts an exemplary embodiment of work implement12.Work implement12 may include ablade30. In the case of a motor grader,blade30 may be attached to a drawbar/moldboard/circle assembly (DMC)32, which may include adrawbar34, amoldboard36, and acircle38.Circle38 may be rotatably attached tomoldboard36.Moldboard36 may be attached todrawbar34, which may be attached to afront portion40 ofwork machine10 with a pivotingjoint42.
• Blade30 may be adjusted in several degrees of freedom. In particular,blade30 may be laterally shifted (side shift) in several different ways. For example,DMC32 may be laterally translated in adirection44 by movingdrawbar34 side to side. Becauseblade30 may be attached toDMC32, lateral translation ofDMC32 may result in a side shift ofblade30 indirection46 as indicated by adashed element48. Also,blade30 may be attached to an actuator mechanism (not shown) mounted oncircle38 behindblade30 that may moveblade30 with respect toDMC32 indirection46.
• Additionally, an effective side shift may be accomplished by swivelingblade30. Becausecircle38 may be rotatably attached tomoldboard36 and fixedly attached toblade30, rotation ofcircle38 about anaxis50, in adirection52, may translate into a swivel motion ofblade30.FIG. 3 is a top view ofblade30 showing a swivel motion ofblade30. Adashed element54 representsblade30 after it has been swiveled aboutaxis50. Swivel ofblade30 results in a change in anangle56 between alongitudinal axis58 ofblade30 and a direction oftravel60 ofwork machine10. Swivel ofblade30 can also result in a side shift ofblade30 by causing a change in lateral position of anedge62 ofblade30, as indicated by adistance64.
• Referring toFIG. 4,work machine10 may include aposition monitoring system66, which may be configured to track the position of work implement12 relative to a mapped. landscape.Position monitoring system66 may includecontroller20,GPS receivers24,processor26, monitordisplay28, amemory68, and anangle position sensor70.
• Position monitoring system66 may includememory68 for storing information.Memory68 may be incorporated into a unit withcontroller20 or withprocessor26 or in a single unit including bothcontroller20 andprocessor26.Memory68 may store maps of a work site. The maps stored bymemory68 may also include entities such as obstacles and barriers. These obstacles may include existing structural entities, such as, for example, buildings, utilities infrastructure, fences, curbs, and any other structure to be avoided by a work implement. Possible barriers may include intangible entities, such as, for example, easements, building envelopes, property lines, or any other type of arbitrary boundary. Other possible entities may include projected locations of obstacles or barriers that have yet to be established. For example, while developing a new roadway, a mapped entity representing the intended edge of the roadway may assist an operator in creating the roadway.
• Maps may be downloaded or programmed intoposition monitoring system66 from an outside source. For example, whenwork machine10 is designated for use at a particular work site, pre-established maps of that work site may be downloaded intomemory68. The locations and characteristics of entities may also be programmed intomemory68 as part of a mapped landscape at any given time. For example, coordinates or outlines of entities may be downloaded as part of the pre-established maps discussed above, or entered by an operator ofwork machine10 at the work site.
• Downloading or programming of information intomemory68 may be performed using external devices such as laptops, PDAs, etc. Information transfer tomemory68 may also be performed wirelessly with a network connection to laptops, PDAs, etc., or to a central server at an offsite location.
• In addition,position monitoring system66 may be used to generate maps. For example,position monitoring system66 may record the areas over which workmachine10 was driven, and may establish a map of the work site that indicates areas that were not traversed bywork machine10 as entities. For example, an operator may drivework machine10 over an entire work site except for an area occupied by an existing building.Position monitoring system66 may establish a map of the work site that indicates the area that was not driven over (i.e. the location of the existing building) as an entity. This mapped entity may be designated as an obstacle to be avoided.
• Memory68 may also store other information, such as, for example, positional information aboutwork machine10 and/or work implement12. This information may also be incorporated into one or more maps of the worksite. As an example,memory68 may store a positional history of wherework machine10 and/or work implement12 have been (e.g. the route taken by the operator) in the work site.
• Position monitoring system66 may also includemonitor display28 incab14 for displaying information to an operator.Monitor display28 may be any kind of display, including screen displays, such as, for example, cathode ray tubes (CRTs), liquid crystal displays (LCDs), plasma screens, and the like.
• Monitor display28 may display maps stored inmemory68 or maps generated byposition monitoring system66.Monitor display28 may also represent the past, present, and/or projected future position and orientation ofwork machine10 and/or work implement12 in relation to the maps. For example, monitordisplay28 may show a trail indicating wherework machine10 has traveled within the work site. Similarly, monitor display may show a projected route based on the current heading ofwork machine10, or a suggested route for the operator to follow.Monitor display28 may also display other information such as, for example, the amount of time the machine has been operating, work machine systems information (e.g. oil pressure, hydraulic fluid pressure, coolant temperature, etc.), and any other information desired to be displayed to the operator, owner, service technician, or anyone else who may viewmonitor display28.
• Position monitoring system66 may further includeprocessor26.Processor26 may be located at any suitable location onwork machine10.Processor26 may be contained in its own housing or, alternatively, may be housed with other components ofwork machine10.
• Processor26 may receive information from any source from which information is desired to be processed. In particular,processor26 may receive information about the position and orientation of work implement12, including its position with respect to mapped entities, as well as the speed ofwork machine10.Processor26 may receive this information fromGPS receivers24,memory68,angle position sensor70, and a work machine speed sensor (not shown).
• Processor26 may be configured to determine which movements of work implement12 are desired and at what rate they should be made, based on information it receives.Processor26 may send signals tocontroller20 communicating these desired movements.Processor26 may also be configured. to send signals to monitordisplay28 to display the information thatprocessor26 receives and/or processes.
• Controller20 may also be located at any suitable location onwork machine10.Controller20 may be contained in its own housing or, alternatively, may be housed with other components ofwork machine10, including for example,processor26.Controller20 may be an integral part ofposition monitoring system66, as shown inFIG. 4. Alternatively,controller20 may be a separate component fromposition monitoring system66.Controller20 andprocessor26 may be independent components if, for example,position monitoring system66 has been retrofitted to workmachine10, whereinwork machine10 was already equipped withcontroller22. As a further alternative, one ofcontroller20 andprocessor26 may be omitted and its functions performed by the other.
• In any of the aforementioned arrangements,controller20 may be configured to receive information fromprocessor26 regarding the desired movements of work implement12.Controller20 may also be configured to initiate movements of work implement12 in response to information fromprocessor26.Controller20 may be configured to initiate swivel, side shift, and any other desired movements of work implement12. In addition,controller20 may be configured to vary the rate of movement of work implement12 as determined byprocessor26, based on the speed ofwork machine10 and/or a distance to a predetermined area or entity.
• Position monitoring system66 may also include one ormore GPS receivers24 for receiving signals from one ormore GPS satellites72. Alocal positioning unit74 may be used to supplementGPS receivers24.Local positioning unit74 may be a reference station, at or near the work site, which enablesGPS receivers24 to more accurately monitor the position of work implement12.
• In operation, each ofGPS receivers24 may communicate with one ormore GPS satellites72 to determine its position with respect to a selected coordinate system.GPS receivers24 may be attached to one or more locations on work implement12, preferably at one or both ends.
• Asingle GPS receiver24 mounted on work implement12 may determine the position of work implement12 relative to a mapped landscape. With more than oneGPS receiver24, the orientation of work implement12 may also be determined. In an exemplary embodiment, work implement12 may have twoGPS receivers24 mounted on it. The twoGPS receivers24 may be placed at or near the ends of work implement12, so as to determine the position of each of the ends. By knowing the position of each end of work implement12,processor26 may determine the orientation of work implement12. For example,processor26 may determine swivel angle by determining the position of the two ends of work implement12 relative to one another.
• While twoGPS receivers24 may be mounted on work implement12, certain embodiments may include just oneGPS receiver24 mounted on work implement12. In an exemplary embodiment, work implement12 may have asingle GPS receiver24 at one end, for determining its location at a work site.Angle position sensor70 may be included on work implement12 for determining swivel angle. The position of one end of work implement12 may be determined byGPS receiver24. The swivel angle of work implement12 may be determined byangle position sensor70, rather than by determining the position of both ends of work implement12 withGPS receivers24.
• Local positioning unit74 may be any system for determining the position of work implement12 in a coordinate system.Local positioning unit74 may be placed at a surveyed location with a known position.Local positioning unit74 may be part of a differential GPS (DGPS), and may include aGPS receiver76.GPS receiver76 may be used to determine the position oflocal positioning unit74. Any discrepancy between the actual, known position of local positioning unit74 (as established by survey) and its determined position obtained usingGPS receiver76 may be considered to be error on the part ofGPS receiver76. A correction factor may be generated to compensate for any discrepancy and may be used to correct errors in the determined positions oflocal positioning unit74 that are obtained usingGPS receiver76. This correction factor may also be applied to determined positions obtained using other GPS receivers in the vicinity. Accordingly, the correction factor may be used to modify the determined position of work implement12 that is obtained usingGPS receivers24. Use of this correction factor may enable a more accurate position of work implement12 to be determined.
• Alternatively,local positioning unit74 may be a laser-based system for determining the position of work implement12 in the work site.Local positioning unit74 may include a transceiver for communicating withwork machine10. Such systems may be used in a similar manner to a differential GPS as discussed above to improve the accuracy ofposition monitoring system66.
• FIGS. 5 and 6, which are discussed in the following section, illustrate the operation of a work machine utilizing embodiments of the disclosed system.
INDUSTRIAL APPLICABILITY
• The disclosed system may be applicable to a variety of work machines, including motor graders, track-type tractors (e.g. bulldozers), wheeled tractors, loaders, excavators, and any other work machine that may include a work implement. The disclosed system provides automation of work implement motion that can increase efficiency and accuracy of work machine operations.
• The use of work machines can involve operation around entities. These entities may include existing structural obstacles, such as, for example, buildings, utilities infrastructure, fences, curbs, and any other structure to be avoided by a work implement. Other possible entities include intangible boundaries, such as, for example, easements, building envelopes, property lines, or any other type of arbitrary boundary.
• It may be desirable to operate work implement12 within close proximity to these entities. The disclosed control system may automatically move work implement12 such that, when in close proximity to a predetermined entity, a buffer distance is maintained between the entity and an edge of work implement12 nearest to the entity. For example, when operating work implement12 around an entity such as a building, a buffer distance may be maintained between work implement12 and the building, in order to keep work implement12 from contacting the building.
• The buffer distance may be selectable, by an owner, operator, service technician, or anyone else having an interest in such a setting. Alternatively, the buffer distance may be preprogrammed. The buffer distance may be the same for all entities in a particular mapped landscape or may be different for different entities or different kinds of entities. For example, all easements may have a five foot buffer distance associated with them, whereas all building structures may have a three foot buffer distance. In addition, it may be possible to set different buffer distances for different boundaries about the same entity. For example, the buffer distance along one side of a building may be set at a different value than the buffer distance along another side of the building.
• In some situations it may be desired to maintain no buffer distance at all between work implement12 and an entity. For example, in the case of a roadway under construction, it may be desired to maintain an edge of work implement12 exactly at an intended edge or other feature of the roadway. In such a case, it may be desirable to simply set a buffer distance of zero.
• Referring toFIG. 5,controller20 may be configured to maintain a pre-determined buffer distance between work implement12 and an entity. The buffer distance may be as large or small as desired and may be maintained within a predetermined range of accuracy. As an example, it may be desired to follow along anentity78 with work implement12, as shown inFIG. 5. Becauseentity78 may be an existing structure, it may be desired to maintain apredetermined buffer distance80 between work implement12 andentity78.Work machine10 may be driven in a straight line, as indicated by a set of dashedlines82, while the side shift of work implement12 may be controlled to maintainedge62 along aboundary line84, which is atpredetermined buffer distance80 fromentity78.
• Controller20 may also be configured to avoid an entity, without necessarily following along the entity. Referring again toFIG. 5, it may be desired to avoid a predetermined area occupied by anentity86. Further, it may be desired for work implement12 to avoidentity86 by at least apredetermined buffer distance88. For example, aswork machine10 approachesentity86, it may be driven in a straight line as indicated by dashedlines82. Work implement12 may have a preferred path whereinedge62 follows alongboundary line84 in order to follow a contour ofentity78. Aboundary line90 atbuffer distance88 fromentity86 may define abuffer zone92 aboutentity86. Whenedge62 reaches alocation94 at the intersection ofboundary line84 andboundary line90, work implement12 may begin to side shift in order to avoidentity86 andbuffer zone92 aboutentity86. By thetime edge62 reaches alocation96 to the far right ofentity86, it will have side shifted by at least adistance98 from its preferred path alongboundary line84.
• In contrast to following a contour ofentity78, where the distance betweenedge62 andentity78 may be maintained atpredetermined buffer distance80, during avoidance ofentity86, the distance betweenedge62 andentity86 may become greater thanpredetermined buffer distance88. Therefore, once work implement12reaches location96, it may maintain its lateral position aswork machine10 proceeds forward. Alternatively, work implement12 may automatically side shift back toward its preferred position alongboundary line84, thereby following the contour ofboundary line90 around a portion ofentity86. However, whenedge62 reachesboundary line84 at alocation100 it may cease to follow alongboundary line90 and proceed alongboundary line84, thus increasing the distance betweenedge62 andentity86 to be greater thanbuffer distance88.
• The rate of movement of work implement12 may be linked to the speed ofwork machine10. For example, the rate of movement may increase with the speed ofwork machine10. Conversely, the rate of movement may also be decreased as the speed ofwork machine10 increases. The relationship may or may not be linear and may be described with many different functions, including, but not limited to, non-linear functions, step functions, and exponential functions. The relationship between the rate of movement and the speed ofwork machine10 may be varied during operation of work implement12. For example, the rate of movement may decrease linearly as the speed ofwork machine10 decreases, but, as the speed ofwork machine10 approaches zero, the rate of movement may decrease less rapidly, so as to avoid reducing the rate of movement too much. Similarly, as the speed ofwork machine10 approaches its maximum, the rate of movement may increase less rapidly, so as to avoid moving too fast, or too much.
• The rate of movement may also depend on the distance betweenwork machine10 and one or more entities. This relationship may vary as greatly as the relationship between rate of movement and the speed ofwork machine10 discussed above. Also, the relationship may be varied during operation of work implement12. For example, whenwork machine10 is relatively close to anentity102, work implement12 may be required to side shift significantly over ashort distance104 of machine travel in order to avoidentity102. Therefore, initially, theshort distance104 toentity102 would require a relatively fast side shift movement of work implement12. However, aswork machine10 approaches entity102 (i.e. as adistance104 fromwork machine10 toentity102 approaches zero) and work implement12 approaches the desired position and/or orientation, the rate of side shift movement would slow down.
• FIG. 6 illustrates one possible method of controlling side shift. Atstep106,position monitoring system66 may determine an actual position of work implement12 relative to a work site. This position may be determined byprocessor26, using information from one or more GPS receivers, as discussed above.
• At108, a distance may be determined between work implement12 and one or more entities in the mapped landscape.Position monitoring system66 may compare the position of work implement12 with that of one or more mapped entities, and may thereby determine a distance between the one or more entities and the edge of work implement12 nearest to each individual entity. In order to perform this step,position monitoring system66 may determine the distance to all entities in a mapped landscape, or a smaller subset thereof. For example,position monitoring system66 may only determine the distance to the entities forward ofwork machine12.
• At110,processor26 may perform a comparison between the distance determined at step124 and a predetermined buffer distance. As discussed above, the predetermined buffer distance may be selectable.
• At112,controller20 may control movement of work implement12 based on the comparison between the two differences. Specifically,controller20 may side shift work implement12 to maintain a predetermined buffer distance between work implement12 and the entity, or to simply avoid the entity. The process may repeat, continuously analyzing the landscape and controlling work implement12 based on that analysis.
• It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed work implement side shift control system without departing from the scope of the invention. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the invention being indicated by the following claims and their equivalents.

Claims (11)

1-18. (canceled)

19. A method of controlling a work implement for a work machine, comprising:

determining an actual position of a work implement relative to a mapped landscape;

determining a first distance between at least one predetermined entity in the mapped landscape and an edge of the work implement nearest to the at least one predetermined entity;

automatically controlling movement of the work implement to avoid the at least one predetermined entity based on a comparison of the first distance to a predetermined distance;

wherein the work machine has a longitudinal axis aligned with a direction of travel of the work machine and the movement of the work implement includes movement of the edge of the work implement relative to a vertical plane containing the longitudinal axis.

20. The method ofclaim 19, further including:

controlling the work implement to maintain the predetermined distance between the at least one entity and the edge of the work implement.

21. The method ofclaim 20, wherein the predetermined distance is maintained within a predefined range of accuracy.

22. The method ofclaim 19, wherein the work implement includes a blade.

23. The method ofclaim 22, wherein the blade is attached to a drawbar/moldboard/circle assembly (DMC).

24. The method ofclaim 23, wherein moving the edge is achieved by at least one of swiveling the blade and laterally translating the blade.

25. The method ofclaim 19, further including:

tracking the position of the work implement with a position monitoring system.

26. The method ofclaim 19, further including:

generating a map of the work site; and

storing the map in a memory.

27. The method ofclaim 19, wherein the position monitoring system includes one or more global positioning system (GPS) receivers.

28. The method ofclaim 27, wherein the position monitoring system is configured to receive data from a local positioning unit for supplementing information provided by the one or more GPS receivers.

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