Apparatus and method for controlling a hydraulic excavator

• US 4,866,641 A
• Filed: 06/24/1988
• Issued: 09/12/1989
• Est. Priority Date: 04/24/1987
• Status: Expired due to Term

• Current Assignee: Laser Alignment, Inc. (Hexagon AB)
• Original Assignee: Laser Alignment, Inc. (Hexagon AB)
• Inventors: Steenwyk, Timothy E., Nielsen, Edward G.
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): Teska, Kevin J.
• Application Number:
  US07/211,551
• Time in Patent Office: 445 Days
• Field of Search: 364/167.01, 364/424.07, 364/433, 364/505, 364/559, 364/561, 364/567, 73/1 E, 73/151, 73/146, 340/685, 340/686, 212/153, 172/4.5, 172/430, 414/698-700, 37/DIG. 20
• US Class Current: 700/302
• CPC Class Codes: E02F 3/435 for dipper-arms, backhoes or the like
• CPC Class Codes: E02F 3/437 providing automatic sequences of movements, e.g. linear excavation, keeping dipper angle constant
• CPC Class Codes: E02F 9/264 Sensors and their calibration for indicating the position of the work tool

Abstract

A control for an excavator controls the position of the bucket cutting edge to a desired depth accurately by a calibrating laser receiving mounted on the excavator stick member and passed through a stationary laser plane wherever the stick is moved into or out of a trench. Linear position encoders monitor the length that the actuating cylinders are extended and lookup tables convert the encoder outputs to angle representations for determining the positions of the laser receiver and the cutting edge. Other lookup tables are utilized to avoid time-consuming iterative calculation procedures to provide real-time digital process solutions of trigonometric functions. The apparatus includes a unique laser receiver comprising a plurality of linearly aligned photo receptors with associated circuitry for producing an output representative of the receptor illuminated or, if a group of receptors are illuminated, the centermost receptor illuminated.

Claims

1. A system for an excavator having a frame, cutting means, connecting means pivotally mounted to said frame for connecting said cutting means to said frame, actuation means for moving said cutting means, the position of said cutting means having a component that is related to the angle between said connecting means and said frame, the relationship between said component and said angle defined by a trigonometric function, said system comprising:

angle sensing means for producing a first angle representation proportional to said angle between said connecting means and said frame;

a first lookup table comprising storage means for storing a respective value of a first number related to said component for a corresponding each of a plurality of values of said first angle representation;

first sampling means for repetitively reading the value of said first angle representation; and

first retrieving means for retrieving from said lookup table the value of said first number corresponding to said angle representation, whereby said component is rapidly determined without performing a trigonometric calculation.

2. The system in claim 1 wherein each said respective value of said first number is stored in said lookup table at a unique address and wherein said retrieving means comprises conversion means for converting said angle representation into an address number corresponding to the address within said lookup table at which the respective value of said first number is stored, means for applying said address number to said lookup table and means to read the value at the respective said address.

3. The system in claim 1 wherein said connecting means comprises a boom pivotally mounted at a proximal end thereof to said frame;

a stick pivotally mounted at a proximal end thereof to a distal end of said boom and a bucket pivotally mounted at a proximal end thereof to a distal end of said stick;

a distal end of said bucket defining said cutting means;

said system further comprising stick angle sensing means for producing a second angle representation proportional to the angle between said stick and said boom, bucket angle sensing means for producing a third angle representation proportional to the angle between said bucket and said stick, a second lookup table, a second sampling means for repetitively reading the value of said second angle representation, second retrieving means for retrieving a second number related to said component for a corresponding each of a plurality of values of a number dependent on said second angle representation, a third lookup table, a third sampling means for repetitively reading the value of said third angle representation, third retrieving means for retrieving a third number related to said component of a corresponding each of a plurality of values of a number dependent on said third angle representation and means for combining said first, second and third numbers to obtain said component.

4. The system in claim 3 wherein said actuation means comprises a first hydraulic cylinder between said frame and said boom, a second hydraulic cylinder between said boom and said stick and a third hydraulic cylinder between said stick and said bucket and wherein said output means controls said first cylinder.

5. The system in claim 4 wherein said angle sensing means comprises a first encoding means for producing a first length representation proportional to the distance said first hydraulic cylinder is extended and first translating means for translating said first length representation to said first angle representation.

6. The system in claim 5 wherein said stick angle sensing means comprises a second encoding means for producing a second length representation proportional to the distance said second hydraulic cylinder is extended and second translating means for translating said second length representation to said second angle representation.

7. The system in claim 6 wherein said bucket angle sensing means comprises a third encoding means for producing a third length representation proportional to the distance said third hydraulic cylinder is extended and third translating means for translating said third length representation to said third angle representation.

8. The system in claim 1 further having a desired position storage means for storing a value of said component corresponding to the position to which said cutting means is to be moved, comparison means for comparing said value in said storage means with said component, and output means responsive to said comparison means for controlling said actuation means so as to cause said cutting means to approach said desired position.

9. The system in claim 8 wherein said connecting means comprises a boom pivotally mounted at a proximal end thereof to said frame;

a stick pivotally mounted at a proximal end thereof to a distal end of said boom and a bucket pivotally mounted at a proximal end thereof to a distal end of said stick;

a distal end of said bucket defining said cutting means;

said system further comprising stick angle sensing means for producing a second angle representation proportional to the angle between said stick and said boom, bucket angle sensing means for producing a third angle representation proportional to the angle between said bucket and said stick, a second lookup table, a second sampling means for repetitively reading the value of said second angle representation, second retrieving means for retrieving a second number related to said component for a corresponding each of a plurality of values of a number dependent on said second angle representation, a third lookup table, a third sampling means for repetitively reading the value of said third angle representation, third retrieving means for retrieving a third number related to said component for a corresponding each of a plurality of values of a number dependent on said third angle representation and means for combining said first, second and third numbers to obtain said component.

10. The system in claim 9 wherein said actuation means comprises a first hydraulic cylinder between said frame and said boom, a second hydraulic cylinder between said boom and said stick and a third hydraulic cylinder between said stick and said bucket and wherein said output means control said first cylinder.

11. The system in claim 10 wherein said angle sensing means comprises a first encoding means for producing a first length representation proportional to the distance said first hydraulic cylinder is extended and first translating means for translating said first length representation to said first angle representation.

12. The system in claim 11 wherein said translating means comprises a fourth lookup table comprising storage means for storing a respective value of a fourth number related to said first angle representation for a corresponding each of a plurality of values of said first length representation, fourth sampling means for repetitively reading the value of said first length representation and fourth retrieving means for retrieving from said fourth lookup table the value of said fourth means corresponding to each value read by said fourth sampling means.

13. The system in claim 12 wherein said stick angle sensing means comprises a second encoding means for producing a second length representation proportional to the distance said second hydraulic cylinder is extended and second translating means for translating said second length representation to said second angle representation.

14. The system in claim 13 wherein said bucket angle sensing means comprises a third encoding means for producing a third length representation proportional to the distance said third hydraulic cylinder is extended and third translating means for translating said third length representation to said third angle representation.

15. The system in claim 14 wherein said second translating means comprises a fifth lookup table, sampling means and retrieving means and further wherein said third translating means comprises a sixth lookup table, sampling means and retrieving means.

16. A system for an excavator having a frame, cutting means, connecting means pivotally mounted to said frame for connecting said cutting means to said frame, actuation means comprising a first linearly extendable device connected between said frame and said connecting means for moving said cutting means, the position of said cutting means having a component that is related to the angle between said connecting means and said frame, said system comprising:

first encoding means for producing a first length representation proportional to the distance said first extendable device is extended from a reference position;

first translating means for translating said first length representation into a first angle representation that is proportional to the angle between said connecting means and said frame; and

means responsive to said first angle representation for producing a value of said component.

17. The system of claim 16 wherein said translating means comprises a lookup table comprising storage means for storing a respective value of a first number related to said first angle representation for a corresponding each of a plurality of values of said first length representation, sampling means for repetitively reading the value of said first length representation and retrieving means for retrieving from said lookup table the value of said first number corresponding to each value of said first length representation read by said sampling means.

18. The system in claim 16 wherein said connecting means comprises a boom pivotally mounted at a proximal end thereof to said frame, a stick pivotally mounted at a proximal end thereof to a distal end of said boom and a bucket pivotally mounted at a proximal end thereof to a distal end of said stick, a distal end of said bucket defining said cutting means, wherein said first linearly extendable device is connected between said frame and said boom and wherein said actuation means further comprises a second linearly extendable device connected between said boom and said stick and a third linearly extendable device connected between said stick and said bucket and wherein said system further comprises:

second encoding means for producing a second length representation proportional to the distance said second extendable device is extended from a reference position;

second translating means for translating said second length representation into a second angle representation that is proportional to the angle between said boom and said stick;

third encoding means for producing a third length representation proportional to the distance said third extendable device is extended from a reference position;

third translating means for translating said third length representation into a third angle representation that is proportional to the angle between said stick and said bucket; and

means responsive to said first, second and third angle representations for producing a position representation proportional to said component of the distance between said cutting means and said frame.

19. The system in claim 18 wherein said linearly extendable devices are hydraulic cylinders.

20. The system in claim 16 further having a desired position storage means for storing a value of said component corresponding to the position to which said cutting means is to be moved, comparison means for comparing said value in said desired position storage means with the value of said component and output means responsive to said comparison means for controlling said actuation means in a manner to cause said cutting means to approach said desired position.

21. The system in claim 20 wherein said connecting means comprises a boom pivotally mounted at a proximal end thereof to said frame, a stick pivotally mounted at a proximal end thereof to a distal end of said boom and a bucket pivotally mounted at a proximal end thereof to a distal end of said stick, a distal end of said bucket defining said cutting means, wherein said first linearly extendable device is connected between said frame and said boom and wherein said actuation means further comprises a second linearly extendable device connected between said boom and said stick and a third linearly extendable device connected between said stick and said bucket and wherein said system further comprises:

second encoding means for producing a second length representation proportional to the distance said second extendable device is extended from a reference position;

second translating means for translating said second length representation into a second angle representation that is proportional to the angle between said boom and said stick;

third encoding means for producing a third length representation proportional to the distance said third extendable device is extended from a reference position;

third translating means for translating said third length representation into a third angle representation that is proportional to the angle between said stick and said bucket; and

means responsive to said first, second and third angle representations for producing a position representation proportional to said component of the distance between said cutting means and said frame and wherein said comparison means comprises means for comparing said value in said storage means with the said position representation.

22. The system in claim 21 wherein said linearly extendable devices are hydraulic cylinders.

23. A system for an excavator having a frame, cutting means, connecting means pivotally mounted to said frame for connecting said cutting means to said frame, means including a linearly extendable device connected between said connecting means and said frame for moving said cutting means, the position of said cutting means having a component that is related to the angle between said connecting means and said frame, the relationship between said component and said angle defined by a trigonometric function, said system comprising:

angle sensing means for producing a first angle representation proportional to said angle between said connecting means and said frame, said angle sensing means including a first encoding means for producing a first length representation proportional to the distance said linearly extendable device is extended and first translating means for translating said first length representation to said first angle representation;

a first lookup table comprising storage means for storing a respective value of a first number related to said component for a corresponding each of a plurality of values of said first angle representation;

first sampling means for repetitively reading the value of said first angle representation; and

first retrieving means for retrieving from said lookup table the value of said first number corresponding to said angle representation, whereby said component is rapidly determined without performing a trigonometric calculation.