Self-adapting excavation control system and method

• US 5,682,312 A
• Filed: 03/18/1996
• Issued: 10/28/1997
• Est. Priority Date: 03/23/1994
• Status: Expired due to Fees

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Rocke, David J.
• Primary Examiner(s): PARK, COLLIN
• Application Number:
  US08/618,079
• Time in Patent Office: 589 Days
• Field of Search: 364/167.01, 364/181, 364/424.07, 37/414, 37/416, 172/4.5, 414/699, 395/904
• US Class Current: 701/50
• CPC Class Codes: E02F 3/437 providing automatic sequences of movements, e.g. linear excavation, keeping dipper angle constant
• CPC Class Codes: E02F 3/439 Automatic repositioning of the implement, e.g. automatic dumping, auto-return E02F3/438 takes precedence

Abstract

A control system for automatically controlling a work implement of an excavating machine through a machine work cycle in disclosed. The work implement including a boom, stick and bucket, each being controllably actuated by at least one respective hydraulic cylinder. A plurality of command signal magnitudes associated with at least one hydraulic cylinder are stored. The command signal magnitudes are represented by a plurality of control curves, where each control curve is responsive to a material condition setting that is representative of a predetermined condition of the excavating material. A microprocessor selects one of the plurality of control curves and responsively produces a command signal having a magnitude dictated by the selected control curve. A electrohydraulic system receives the command signal and controllably actuates predetermined ones of the hydraulic cylinders to perform the work cycle.

Claims

1. A control system for automatically controlling a work implement of an excavating machine through a machine work cycle, the work implement including a boom, stick and bucket, each being controllably actuated by at least one respective hydraulic cylinder, the hydraulic cylinders containing pressurized hydraulic fluid, the control system comprising:

memory means for storing a plurality of command signal magnitudes for controlling at least one hydraulic cylinder, the command signal magnitudes being represented by a plurality of control curves, each control curve corresponding to a material condition setting that is representative of a condition of an excavated material;

logic means for selecting one of the plurality of control curves responsive to a determined said material condition setting indicated by the condition of the excavated material and producing command signals having a magnitude dictated by the selected said control curve; and

actuating means for receiving the command signals and responsively actuating predetermined ones of the hydraulic cylinders to perform the work cycle.

2. A control system, as set forth in claim 1, wherein said logic means determines the condition of material excavated during a work cycle and automatically selects said one of the plurality of control curves, said logic means producing said command signals from said selected control curve during a subsequent work cycle in response to the determined material condition setting.

3. A control system, as set forth in claim 2, including an operator interface means for providing the operator an option of manually selecting one of the plurality of control curves.

4. A control system, as set forth in claim 1, wherein said logic means produces said command signals having magnitudes dictated by said selected control curve responsive to a force imposed on a said hydraulic cylinder.

5. A control system, as set forth in claim 4, further comprising hydraulic fluid pressure sensors for measuring said force imposed on said hydraulic cylinder.

6. A method for automatically controlling a work implement of an excavating machine through a machine work cycle, the work implement including a boom, stick and bucket, each being controllably actuated by at least one respective hydraulic cylinder, the hydraulic cylinders containing pressurized hydraulic fluid, the method comprising the steps of:

storing a plurality of command signal magnitudes associated with at least one hydraulic cylinder, the command signal magnitudes being represented by a plurality of control curves, each control curve corresponding to a material condition setting that is representative of a condition of an excavated material;

selecting one of the plurality of control curves responsive to a material condition setting determined from said excavated material condition and producing a command signal having a magnitude dictated by the selected control curve, responsive to a force imposed on a said hydraulic cylinder;

receiving the command signal and controllably actuating predetermined ones of the hydraulic cylinders in response to said command signal to perform the work cycle.

7. A method, as set forth in claim 6, further including the step of determining said material condition setting based on the condition of material excavated during a single work cycle and automatically selecting one of the plurality of control curves in response to the determined material condition setting.

8. A method, as set forth in claim 7, including the steps of:

calculating a bucket payload value;

calculating the work performed by stick and bucket cylinders during a digging portion of the work cycle; and

deriving a bucket payload/work quotient value by dividing the bucket payload value by the work performed, the divisional result being indicative of a condition of the material.

9. A method, as set forth in claim 8, including the steps of:

storing a plurality of predetermined bucket payload/work quotient values corresponding to a plurality of predetermined material condition values;

comparing the calculated bucket payload/work quotient value to the stored bucket payload/work quotient values; and

selecting one of the plurality of control curves in response to the comparison.

10. A method, as set forth in claim 7, including the steps of:

calculating a bucket payload value;

calculating the time elapsed during a single pass of the digging portion of the work cycle; and

dividing the bucket payload value by the elapsed time to determine a productivity value for the digging pass, the productivity value being indicative of a condition of the material.

11. A method, as set forth in claim 10, including the steps of:

storing a plurality of predetermined productivity values corresponding to a plurality of predetermined material condition values;

comparing the calculated productivity value to the stored productivity values; and

selecting one of the plurality of control curves in response to the comparison.

12. A control system, as set forth in claim 7, including the steps of:

calculating a bucket payload value; and

estimating a bucket fill percentage, said bucket fill percentage being representative of the amount that the bucket is filled with excavated material, said bucket fill percentage being function of said bucket payload value and indicative of a condition of the material.

13. A method, as set forth in claim 12, including the steps of:

storing a plurality of predetermined bucket fill values corresponding to a plurality of predetermined material condition values;

comparing the estimated bucket fill value to the stored bucket fill values; and

selecting one of the plurality of control curves in response to the comparison.

14. A method, as set forth in claim 7, including the steps of:

calculating a moment arm magnitude value, said moment arm magnitude value being representative of the external force acting on the bucket, said moment arm magnitude value being indicative of a condition of the material.

15. A method, as set forth in claim 14, including the steps of:

storing a plurality of predetermined moment arm magnitude values corresponding to a plurality of predetermined material condition values;

comparing the calculated moment arm magnitude value to the stored moment arm magnitude values; and

selecting one of the plurality of control curves in response to the comparison.

16. A control system for automatically controlling a work implement through a machine work cycle, said implement having a bucket controllably actuated by at least one hydraulic cylinder, comprising:

memory means for storing a plurality of command signal magnitudes for controlling said at least one hydraulic cylinder, said command signal magnitudes being described in correspondence with respective hydraulic cylinder pressures by a plurality of control curves, each control curve corresponding to a material condition setting that is representative of a condition of an excavated material;

logic means for selecting one of the plurality of control curves responsive to a determined said material condition setting indicated by the condition of the excavated material and responsively producing command signals having a magnitude dictated by the selected said control curve; and

actuating means for receiving the command signals and responsively actuating predetermined ones of the hydraulic cylinders to perform the work cycle.

17. A control system, as set forth in claim 16, further comprising said logic means determining said material condition setting based on the condition of material excavated during a digging portion of a work cycle and automatically selecting one of the plurality of control curves to control a subsequent subsequent work cycle in response to the determined material condition setting.

18. A control system, as set forth in claim 17, further comprising said logic means:

calculating a bucket payload value;

calculating a second value representing at least one of the elapsed time and the work required to excavate said material; and

determining said material condition on the basis of a ratio between said payload and said second values.

19. A control system, as set forth in claim 17, further comprising said logic means:

calculating a bucket payload value; and

estimating a bucket fill percentage, said bucket fill percentage being representative of the amount that the bucket is filled with excavated material, said bucket fill percentage being function of said bucket payload value and indicative of a condition of the material.