Adaptive payload monitoring system

• US 20090228394A1
• Filed: 03/07/2008
• Published: 09/10/2009
• Est. Priority Date: 03/07/2008
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: King, Kevin D., Tozawa, Shoji, Price, Robert J., Janardhan, Vijayakumar, Mintah, Brian
• Granted Patent: US 8,156,048 B2
• Time in Patent Office: Days
• US Class Current: 705/50
• CPC Class Codes: E02F 9/2029 Controlling the position of implements in function of its load, e.g. modifying the attitude of implements in accordance to vehicle speed control for hydraulic or pneumatic drives E02F9/2203, E02F9/2221 and E02F9/2253 take precedence
• CPC Class Codes: E02F 9/264 Sensors and their calibration for indicating the position of the work tool
• CPC Class Codes: G01G 19/10 having fluid weight-sensitive devices

Abstract

A payload monitoring system for an excavation machine is disclosed. The payload monitoring system may have a tool, a first sensor configured to generate a first signal indicative of a velocity of the tool, and a second sensor configured to generate a second signal indicative of a lift force of the tool. The payload monitoring system may also have a controller in communication with the first sensor and the second sensor. The controller may be configured to record the velocity and the lift force of the tool during a work cycle based on the first and second signals, and partition the work cycle into a plurality of segments including a loaded moving segment. The controller may also be configured to determine a period of time within the loaded moving segment during which the velocity of the tool is substantially constant, and calculate a payload of the tool based on the lift force recorded during the period of time.

Claims

1. A payload monitoring system, comprising:

a tool;

a first sensor configured to generate a first signal indicative of a velocity of the tool;

a second sensor configured to generate a second signal indicative of a lift force of the tool; and

a controller in communication with the first sensor and the second sensor and being configured to;

record the velocity and the lift force of the tool during a work cycle based on the first and second signals;

partition the work cycle into a plurality of segments including a loaded moving segment;

determine a period of time within the loaded moving segment during which the velocity of the tool is substantially constant; and

calculate a payload of the tool based on the lift force recorded during the period of time.

2. The payload monitoring system of claim 1, wherein the velocity is in a swing direction substantially orthogonal to a direction of the lift force.

3. The payload monitoring system of claim 1, wherein the recorded velocity attains a maximum within the period of time.

4. The payload monitoring system of claim 3, wherein the velocities recorded at the bounds of the period of time are substantially equal for a given work cycle.

5. The payload monitoring system of claim 1, wherein a duration of the period of time varies continuously.

6. The payload monitoring system of claim 5, wherein the controller is further configured to average a threshold number of lift force samples taken during the period of time, wherein the duration of the period of time is a function of the threshold number and the velocity.

7. The payload monitoring system of claim 6, wherein the controller is further configured to qualify each lift force sample and expand the period of time until the threshold number of qualified lift force samples is obtained.

8. The payload monitoring system of claim 7, wherein the controller is configured to qualify each lift force sample based on at least one of an operator requested directional change of the tool, an extension status of at least one actuator associated with moving the tool, a stability of the tool movement, or an amount of payload spillage occurring at the time each lift force sample is taken.

9. The payload monitoring system of claim 6, wherein the threshold number is about 100.

10. The payload monitoring system of claim 1, wherein the controller has stored in memory a calibration map relating the first and second signals to a payload.

11. The payload monitoring system of claim 1, wherein the controller is configure to continuously monitor and record the velocity and the lift force of the tool during the work cycle, and post process the recorded velocity and lift force to determine the payload after completion of the work cycle.

12. The payload monitoring system of claim 1, wherein another of the plurality of segments includes an empty moving segment, and the controller is further configured to adjust payload calibration during the empty moving segment.

13. A method of determining payload, comprising:

sensing a velocity of a tool;

sensing a lift force of the tool;

recording the velocity and the lift force of the tool during a work cycle;

partitioning the work cycle into a plurality of segments including a loaded moving segment;

determining a period of time within the loaded moving segment during which the velocity of the tool is substantially constant; and

calculating a payload of the tool based on the lift force recorded during the period of time.

14. The method of claim 13, wherein the velocity is in a swing direction substantially orthogonal to a direction of the lift force.

15. The method of claim 13, wherein:

the recorded velocity attains a maximum within the period of time; and

the velocities recorded at the bounds of the period of time are substantially equal for a given work cycle.

16. The method of claim 13, further including:

averaging a threshold number of lift force samples taken during the period of time; and

qualifying each lift force sample based on at least one of an operator requested directional change of the tool, an extension status of at least one actuator associated with moving the tool, a stability of the tool movement, or an amount of payload spillage occurring at the time each lift force sample is taken.

17. The method of claim 13, wherein another of the plurality of segments includes an empty moving segment, and the method further includes adjusting payload calibration during the empty moving segment.

18. A machine, comprising:

a tool;

a linkage member pivotally connected to the tool;

a first actuator configured to swing the linkage member in a first direction;

a first sensor configured to generate a first signal indicative of a swing velocity of the tool;

a second actuator configured to lift the linkage member in a second direction substantially orthogonal to the first direction;

a second sensor configured to generate a second signal indicative of a lift force of the tool; and

a controller in communication with the first sensor and the second sensor and being configured to;

continuously record the swing velocity and the lift force of the tool during a work cycle based on the first and second signals;

partition the work cycle into a dig segment, a loaded moving segment, a dump segment, and an empty moving segment;

determine a period of time within the loaded moving segment during which the velocity of the tool is substantially constant and attains a maximum; and

calculate a payload of the tool based on a threshold number of qualified lift force samples recorded during the period of time after completion of the work cycle.

19. The machine of claim 18, wherein:

the velocities recorded at the bounds of the period of time are substantially equal for a given work cycle;

a duration of the period of time varies continuously; and

the controller is further configured to average a threshold number of lift force samples taken during the period of time, wherein the duration of the period of time is a function of the threshold number and the velocity.

20. The machine of claim 19, wherein:

the controller is further configured to qualify each lift force sample and expand the period of time until the threshold number of qualified lift force samples is obtained; and

the controller is configured to qualify each lift force sample based on at least one of an operator requested directional change of the tool, an extension status of at least one actuator associated with moving the tool, a stability of the tool movement, or an amount of payload spillage occurring at the time each lift force sample is taken.