Classifications

• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02F—DREDGING; SOIL-SHIFTING
  • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
  • E02F9/20—Drives; Control devices
  • E02F9/2025—Particular purposes of control systems not otherwise provided for
  • E02F9/2045—Guiding machines along a predetermined path
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02F—DREDGING; SOIL-SHIFTING
  • E02F3/00—Dredgers; Soil-shifting machines
  • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
  • E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
  • E02F3/36—Component parts
  • E02F3/42—Drives for dippers, buckets, dipper-arms or bucket-arms
  • E02F3/43—Control of dipper or bucket position; Control of sequence of drive operations
  • E02F3/435—Control of dipper or bucket position; Control of sequence of drive operations for dipper-arms, backhoes or the like

Definitions

• the present invention relates to excavators and similar types of machines and, more particularly, to a system and method for determining the orientation of the machine or a part of the machine without necessitating the use of additional sensors, detectors or receivers.
• Excavators are used for excavating at construction sites, quarries, agricultural sites, and similar environments. To control an excavator with precision, it is important to know the position and the orientation of the excavator, including its cab, its boom, its dipper stick, and its bucket. A number of different arrangements have been used to collect this information. For example, a GPS antenna and receiver provide information as to the location of the excavator in three dimensions. However, a single GPS receiver and antenna cannot provide information about the orientation of the excavator, nor of the relative positions of the various components of the excavator.
• the control system of the excavator typically knows the location of the excavator from the GPS system.
• the control system further knows the orientation of the cab and chassis with respect to vertical, i.e., whether the cab is oriented with a non-zero roll angle (side-to-side) or a non-zero pitch angle (front-to-back).
• the rotation of the cab and chassis on the undercarriage leaves the control system without information as to the direction that the cab is aligned with unless a compass with a read-out is mounted on the cab.
• the need is met by a system and method according to the present invention for determining the orientation, r, of an excavator sitting on a sloped portion of a construction site with respect to the direction of zero cross-slope. This direction across the site in which there is no slope is perpendicular to the direction of the fall line.
• the system includes a first inclinometer for determining the pitch angle, Pitch, of the excavator and for providing a pitch angle output.
• the system includes a second inclinometer for determining the roll angle, Roll, of the excavator and for providing a roll angle output.
• the first and second inclinometers may comprise a single, dual axis inclinometer, or they may comprise a pair of appropriately oriented inclinometers.
• the system may use only one of the three formulae continuously, or may select among the formulae for use at various times, depending upon which formula is judged to provide the most accurate indication of orientation.
• the formula may be selected based upon the quadrant in which the excavator is oriented.
• the processor may select a cosine formula when the orientation of the excavator is near ⁇ 90 °, and a sine formula when the orientation of the excavator is near 0 ° or near 180°.
• the step of determining the orientation, r, according to a selected one of the relationships includes the step of selecting among the relationships in dependence upon which relationship is likely to provide the most accurate indication of orientation.
• the steps of selecting among the relationships may include determining the quadrant in which the longitudinal direction of the excavator is found.
• a cosine formula may be used when the orientation of the excavator is near ⁇ 90°, and a sine formula may be used when the orientation of the excavator is near 0 ° or near 180°.
• the system and method contemplate determining the orientation of the excavator based on the measured pitch angle and measured roll angle of the excavator.
• the measured pitch and roll angles provide an indication of the orientation of the excavator with respect to the construction site.
• FIG. 1 is a schematic drawing of an excavator incorporating the system of the present invention for determining the orientation of an excavator;
• FIG. 2 is a schematic representation of a sloped work site
• FIG. 3 is a schematic representation of a sloped work site, with that angular variables encountered in with an excavator incorporating the system of the present invention.
• FIG. 1 depicts an excavator 10 of the type that may incorporate the system of the present invention for determining the orientation of the excavator sitting on a sloped portion of a construction site with respect to the direction across the site in which there is no slope, which is perpendicular to the direction of the fall line of the sloped portion.
• the excavator includes a chassis 1 1 , a boom 12 pivotally secured to the chassis 10 at a first pivot joint 14, a dipper stick 16 pivotally secured to the boom 12 at a second pivot joint 18, and a bucket 20 pivotally secured to the dipper stick 16 at a third pivot joint 22.
• Hydraulic cylinders 24, 26, and 28 are actuated to effect the relative movement of boom 12, dipper stick 16, and bucket 20, respectively.
• Bucket 20 includes a cutting edge 30 that may have serrated teeth. Bucket 20 may also have the freedom to tilt in the direction of the roll axis.
• the chassis 1 1 carries a cab 31 and is supported on an undercarriage support and transport 32 which may include track belts that facilitate the movement of the excavator 10 over the job site.
• the chassis 1 1 and the components it carries can be rotated about a generally vertical axis 34 with respect to the undercarriage support and transport 32 to place the bucket 20 at the precise location needed for excavation. For the operator to control the operation of the excavator either manually or through an automated control system, information regarding the location and orientation of the excavator must be determined.
• the location of the excavator may be determined in any one of a number of ways, including using a laser positioning system, using a GPS positioning system, or using a system that combines laser and GPS positioning.
• the relative positions of the boom 12, the dipper 16, and the bucket 20 may be determined by angle encoders, gravity based inclinometers, or similar sensors associated with pivot joints 14, 18, and 22, or by string encoders associated with cylinders 24, 26, and 28, or by some combination of such sensors.
• the orientation of the excavator 10 with respect to true vertical is determined by inclinometers 36 and 38, which are mounted on the chassis 1 1 .
• the inclinometer 36 provides an indication of the angle of roll and the inclinometer 38 provides an indication of the angle of pitch of the chassis 1 1 .
• roll inclinometer 36 and pitch inclinometer 38 may be mounted in the same housing, or even be the same sensor if the inclinometer is capable of measuring two directions at once, without detracting from the present invention.
• the system includes a processor 50 which retrieves the anticipated slope of the job site at the excavator's location, and then from the outputs of the inclinometers 36 and 38 determines whether the chassis 1 1 of the excavator 10 is oriented across the slope (zero pitch and maximum roll), up or down the fall line (maximum pitch and zero roll), or in some orientation in between these extremes.
• a processor 50 which retrieves the anticipated slope of the job site at the excavator's location, and then from the outputs of the inclinometers 36 and 38 determines whether the chassis 1 1 of the excavator 10 is oriented across the slope (zero pitch and maximum roll), up or down the fall line (maximum pitch and zero roll), or in some orientation in between these extremes.
• FIG. 2 simplistically shows a sloped plane 60 in space.
• the plane has two definite directions of interest - the direction of no slope 62, and the direction of maximum slope 64 - and that these directions are always at right angles to each other.
• the job site on which the excavator is working will have previously been surveyed, prior to the operation of the system of the present invention, and these two orthogonal directions 62 and 64 will have been identified for each point on the surface of the job site. This information may have been stored in memory associated with and accessible by the processor 50.
• the present invention includes two slope-sensing devices - inclinometers 36 and 38. These inclinometers change their orientation with respect to the surface of the job site as the chassis 1 1 rotates around axis 34, but they always remain perpendicular to each other.
• the values of the outputs from the inclinometers 36 and 38 may be designated “Roll” and "Pitch,” respectively. Note that when one of these inclinometers is aligned with the direction of maximum slope, it measures maximum slope, while the other inclinometer measures zero slope. When the alignment of one of the devices moves away from the orientation of maximum slope, the slope measured by the device decreases from the maximum value of the slope.
• line oc represents the direction of maximum slope.
• Line oa represents the direction of zero slope.
• the direction ob indicates the orientation of the pitch axis with respect to the plane.
• the angle r indicates the rotation of the pitch axis of a machine from the zero slope direction of the plane, angle aob. Note that angles bco and aob are equal. Hence, the resulting slope measurement along the direction ob should be scaled by the sine of angle r:
• the sine function is more sensitive than the cosine function for angles around 0 Q and 180 Q .
• the cosine function is more sensitive than the sine function for angles around ⁇ 90 Q .
• the selection of the pitch axis of the machine as the reference is arbitrary.
• the direction of zero slope is, in a sense, arbitrary to the work site. Even though the calculation determines the absolute angle of the machine axis from the zero slope direction, it can only be used for relative reference.

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• Engineering & Computer Science (AREA)
• Mining & Mineral Resources (AREA)
• Civil Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structural Engineering (AREA)
• Mechanical Engineering (AREA)
• Road Paving Machines (AREA)
• Operation Control Of Excavators (AREA)
• Component Parts Of Construction Machinery (AREA)
• Length Measuring Devices With Unspecified Measuring Means (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 2006
  • 2006-06-29 US US11/478,389 patent/US20080000111A1/en not_active Abandoned
• 2007
  • 2007-06-26 AU AU2007265131A patent/AU2007265131A1/en not_active Abandoned
  • 2007-06-26 JP JP2009518501A patent/JP2009542941A/ja not_active Withdrawn
  • 2007-06-26 CN CNA2007800246283A patent/CN101479431A/zh active Pending
  • 2007-06-26 EP EP07799027A patent/EP2038487A2/en not_active Withdrawn
  • 2007-06-26 WO PCT/US2007/072089 patent/WO2008002898A2/en active Application Filing

Non-Patent Citations (1)

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