Method and apparatus for identifying load cycle functions

• US 5,105,895 A
• Filed: 08/20/1990
• Issued: 04/21/1992
• Est. Priority Date: 08/20/1990
• Status: Expired due to Term

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Kyrtsos, Christos T.
• Primary Examiner(s): MILLER JR, GEORGE
• Application Number:
  US07/569,900
• Time in Patent Office: 610 Days
• Field of Search: 177/25.14, 177/139, 177/141, 177/185
• US Class Current: 177/25.14
• CPC Class Codes: G01G 19/08 for incorporation in vehicles

Abstract

In many applications, a loader performs a loading operation that includes, sequentially: digging and/or crowding a stock pile, racking back the bucket to maintain the load, travelling to a dump site or a transport vehicle while raising the bucket, and finally dumping the load from a raised position. For many devices, such as payload monitors and productivity indicators, it is important to have an indication of which function in the loading operation is being performed. A loading function identifier senses, stores, and averages the hydraulic pressure in a lift cylinder. The sensed and averaged data are compared to a series of predetermined constants to identify the function being performed. The algorithms used in this invention are applicable to a number of work vehicles having at least one work implement linkage and at least one hydraulic cylinder for modifying the linkage geometry.

Claims

1. An apparatus for a vehicle having at least one lift cylinder for elevating a payload carrier, said vehicle generally executing a plurality of functions in a loading cycle, comprising:

means for sensing the hydraulic pressure of said lift cylinder and responsively producing a plurality of pressure signals;

means for storing said plurality of pressure signals and at least one predetermined constant;

means for retrieving said plurality of pressure signals and said predetermined constant; and

means for identifying the function being performed in the loading cycle in response to said plurality of pressure signals and said predetermined constant.

2. An apparatus, as set forth in claim 1, wherein said means for identifying the function includes means for time averaging said plurality of pressure signals and thereby producing a plurality of average pressure signal.

3. An apparatus, as set forth in claim 1, wherein said means for identifying the function includes:

means for deriving a second order time dependent polynomial in response to said plurality of pressure signals;

means for producing a first signal being indicative of the degree of fit of said plurality of pressure signals to said second order time dependent polynomial; and

means for detecting a lifting function in response to said first signal exceeding a first predetermined constant.

4. An apparatus, as set forth in claim 3, including:

means for comparing one of said pressure signals to another of said pressure signals and responsively producing a difference signal; and

means for detecting an end of lift function in response to said difference signal exceeding a second predetermined constant.

5. An apparatus, as set forth in claim 1, wherein said means for identifying the function includes:

means for comparing one of said pressure signals to another of said pressure signals and responsively producing a difference signal; and

means for detecting a digging function in response to said difference signal exceeding a predetermined constant.

6. An apparatus, as set forth in claim 5, including:

means for time averaging said plurality of pressure signals and thereby producing a plurality of average pressure signals;

means for detecting a maximum average pressure signal in a preselected number of said plurality of average pressure signals; and

means for detecting an end of dig function in response to a quotient of said maximum average pressure signal divided by said average pressure signal exceeding a second predetermined constant.

7. An apparatus, as set forth in claim 1, wherein said means for identifying the function includes:

means for comparing one of said pressure signals to another of said pressure signals and responsively producing a difference signal; and

means for detecting a roading function in response to said difference signal being greater than a first predetermined constant and less than a second predetermined constant.

8. An apparatus, as set forth in claim 7, including means for detecting an end of roading function in response to said difference signal being less than said predetermined constant.

9. An apparatus, as set forth in claim 1, wherein said means for identifying the function includes:

means for identifying a maximum pressure signal in a preselected number of said plurality of said average pressure signals;

means for comparing one of said pressure signals to another of said pressure signals and responsively producing a difference signal; and

means for detecting a dumping function in response to said maximum pressure signal exceeding a first pressure signal and said difference signal being less than a second predetermined constant.

10. A method for determining which of a plurality of functions in a loading cycle is being performed by a vehicle having at least one lift cylinder for elevating a payload carrier, comprising the steps of:

sensing the hydraulic pressure of said lift cylinder and responsively producing a plurality of pressure signals;

storing said plurality of pressure signals and at least one predetermined constant;

retrieving said plurality of pressure signals and said predetermined constant; and

identifying the function being performed in the loading cycle in response to said plurality of pressure signals and said predetermined constant.

11. A method, as set forth in claim 10, wherein said step of identifying the function includes the steps of:

deriving a second order time dependent polynomial in response to said plurality of pressure signals;

producing a first signal being indicative of the degree of fit of said plurality of pressure signals to said second order time dependent polynomial; and

detecting a lifting function in response to said first signal exceeding a first predetermined constant.

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

comparing one of said pressure signals to another of said pressure signals and responsively producing a difference signal; and

detecting an end of lift function in response to said difference signal exceeding a second predetermined constant.

13. A method, as set forth in claim 10, wherein said step of identifying the function includes the steps of:

comparing one of said pressure signals to another of said pressure signals and responsively producing a difference signal; and

detecting a digging function in response to said difference signal exceeding a predetermined constant.

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

time averaging said plurality of pressure signals and thereby producing a plurality of average pressure signals;

detecting a maximum average pressure signal in a preselected number of said plurality of average pressure signals; and

detecting an end of dig function in response to a quotient of said maximum average pressure signal divided by one of said average pressure signals exceeding a second predetermined constant.

15. A method, as set forth in claim 10, wherein said step of identifying the function includes the steps of:

comparing one of said pressure signals to another of said pressure signals and responsively producing a difference signal; and

detecting a roading function in response to said difference signal being greater than a first predetermined constant and less than a second predetermined constant.

16. A method, as set forth in claim 15, including the step of detecting an end of roading function in response to said difference signal being less than said predetermined constant.

17. A method, as set forth in claim 10, wherein said step of identifying the function includes the steps of:

time averaging said plurality of pressure signals and thereby producing a plurality of average pressure signals;

identifying a maximum average pressure signal in a preselected number of said plurality of said average pressure signals;

comparing one of said pressure signals to another of said pressure signals and responsively producing a difference signal; and

detecting a dumping function in response to said maximum average pressure signal exceeding a first predetermined constant and said difference signal being less than a second predetermined constant.