Data processing: generic control systems or specific application – Generic control system – apparatus or process – Digital positioning
Reexamination Certificate
1998-12-02
2001-08-28
Grant, William (Department: 2121)
Data processing: generic control systems or specific application
Generic control system, apparatus or process
Digital positioning
C701S050000
Reexamination Certificate
active
06282453
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to a method for controlling a work implement on a work machine and, more particularly, to a method for determining a desired movement of a work implement and responsively controlling the work implement to prevent interference with the work machine.
BACKGROUND ART
Work machines, such as earthworking machines, are used extensively to perform many tasks. For example, earthworking machines, e.g., bulldozers, excavators, loaders, graders, and the like, are used to cut, move, and shape the earth to desired finished states. The work machines accomplish these tasks by the use of work implements. Examples of work implements for earthworking machines include blades and buckets.
Often, these work implements are controlled by linkages and assemblies which provide several degrees of freedom of motion. The multiple degrees of motion enhance the efficiency and versatility of the work that the machines are capable of producing. In the example of earthworking machines, the linkages and assemblies are hydraulically controlled to increase the output power available by the work implement.
As an example, a typical hydraulically powered excavator has four degrees of freedom; rotation of the excavator body, pivoting motion of a boom, pivoting motion of a stick, and pivoting motion of a bucket. These four degrees of freedom allow the excavator to move efficiently throughout the work area.
The multiple degrees of freedom of motion of the work implement, however, increase the complexity of control that an operator must maintain over the movement of the work implement. In the example of the excavator, an operator must control the rotation of the excavator body, the movement of the boom, the movement of the stick, and the movement of the bucket, sometimes all at once. In work machines having more than four degrees of freedom, the complexity of maintaining control over the movement of the work implement is greatly increased.
The increased complexity of controlling the motion of a work implement having multiple degrees of freedom also increases the probability of moving the implement in a manner that might bring the implement into undesired contact with some portion of the machine; that is, the implement may be brought into interference with the body, frame, tracks, wheels, or some other portion of the machine in an undesirable manner.
Track-type tractors, having dozer blades as work implements, are used to cut and push earth to achieve a desired contour or depth of cut. Typically, the blade on a track-type tractor will have up to four degrees of freedom of motion. However, the mounting configuration of a track-type tractor blade will normally only allow up to three degrees of freedom for a particular work machine. For example, the four degrees of freedom for a dozer blade would be lift (change in elevation of the blade), tilt (change in elevation of one end of the blade), pitch (change in cutting angle of the blade with the earth), and angle (change in the forward extension of one of the two ends of the blade with respect to the other end). A track-type tractor will be designed to allow three of the above degrees of freedom to allow the machine to perform a particular type of work. For example, a track-type tractor designed to push material may be capable of lift, tilt, and angle; but to change the pitch of the blade would require physically changing the mounting linkages of the blade to a different desired pitch. A different track-type tractor may be designed to cut material. This tractor would have lift, tilt, and pitch control; but would not be capable of changing the angle of the blade.
An exemplary track-type tractor blade having all four degrees of freedom of motion is described in detail below. This blade configuration allows simultaneous control of lift, tilt, pitch, and angle, making this blade suitable for both cutting and pushing applications. However, due to the complex interactions of the hydraulic cylinders which control the blade, each of which is independently controlled yet kinematically coupled to each other, this blade control configuration would be nearly impossible for an operator to control, in particular when moving the blade in close proximity to the body, frame, or tracks of the track-type tractor. The present invention is ideally suited to control a work implement such as the exemplary track-type tractor blade discussed below to prevent undesired interference with other portions of the track-type tractor.
The present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of the present invention a method for controllably moving a work implement attached to a work machine is shown. The method includes the steps of inputting a velocity command, determining a plurality of desired cylinder positions as a function of the desired velocity command, and comparing the desired cylinder positions to allowable cylinder positions. The allowable cylinder positions are a function of a combination of the plurality of desired cylinder positions. The method also includes the steps of moving the work implement to a desired work implement position as a function of the desired cylinder positions, and stopping the movement of the work implement in response to at least one desired cylinder position being at a limit defined by a corresponding at least one allowable cylinder position.
In another aspect of the present invention a method for controllably moving a work implement attached to a work machine is shown. The method includes the steps of inputting a velocity command in a work implement frame of reference, transforming the velocity command from the work implement frame of reference to a resolver frame of reference, responsively generating a plurality of desired resolver velocities, and comparing the desired resolver velocities to allowable resolver velocities. The allowable resolver velocities are a function of a combination of the plurality of desired resolver velocities. The method also includes the steps of determining desired resolver positions from the desired resolver velocities, determining desired cylinder positions as a function of the desired resolver positions, moving the work implement as a function of the desired cylinder positions, and stopping the movement of the work implement in response to at least one desired resolver velocity being at a limit of a corresponding at least one allowable resolver velocity.
In yet another aspect of the present invention a method for controllably moving a work implement attached to a work machine is shown. The method includes the steps of inputting a velocity command in a work implement frame of reference, transforming the velocity command from the work implement frame of reference to a cylinder frame of reference, responsively generating a plurality of desired cylinder velocities, and comparing the desired cylinder velocities to allowable cylinder velocities. The allowable cylinder velocities are a function of a combination of the plurality of desired cylinder velocities. The method also includes the steps of determining desired cylinder positions from the desired cylinder velocities, moving the work implement as a function of the desired cylinder positions, and stopping the movement of the work implement in response to at least one desired cylinder velocity being at a limit of a corresponding at least one allowable cylinder velocity.
REFERENCES:
patent: 4755905 (1988-07-01), Telecky, Jr.
patent: 5088020 (1992-02-01), Nishida et al.
patent: 5160239 (1992-11-01), Allen et al.
patent: 5333533 (1994-08-01), Hosseini
patent: 5490081 (1996-02-01), Kuromoto et al.
patent: 5701793 (1997-12-01), Gardner et al.
patent: 5737993 (1998-04-01), Cobo et al.
patent: 5899008 (1999-05-01), Cobo et al.
patent: 6047228 (2000-04-01), Stone et al.
patent: 6129155 (2000-10-01), Lombardi
patent: 6185493 (2001-02-01), Skinner et al.
Caterpillar Inc.
Gain, Jr. Edward F.
Grant William
Lundquist Steve D.
LandOfFree
Method for controlling a work implement to prevent... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for controlling a work implement to prevent..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for controlling a work implement to prevent... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2509516