Method and System for Estimating Payload Weight with Tilt Position Compensation

• US 20150354177A1
• Filed: 06/09/2014
• Published: 12/10/2015
• Est. Priority Date: 06/09/2014
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Shatters, Aaron
• Granted Patent: US 9,464,403 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: E02F 3/3411 of the Z-type
• CPC Class Codes: E02F 3/422 Drive systems for bucket-arms, front-end loaders, dumpers or the like
• CPC Class Codes: E02F 9/264 Sensors and their calibration for indicating the position of the work tool
• CPC Class Codes: G01G 19/083 lift truck scale
• CPC Class Codes: G01G 19/10 having fluid weight-sensitive devices
• CPC Class Codes: G01G 23/01 Testing or calibrating of weighing apparatus

Abstract

A system for estimating the weight of a payload in a bucket is provided. The system includes a pivotable lift linkage, a lift cylinder assembly, a pivotable tilt linkage and a tilt cylinder assembly. A payload measurement system receives pressure data relating to a pressure in the lift cylinder assembly and angular position data relating to an angular position of the bucket relative. The payload measurement system is configured to estimate weight of a payload in the bucket based on the pressure data, the angular position data and predetermined physical parameters relating to the tilt linkage and lift linkage that are useable to characterize an effect of a portion of the payload that is supported by the tilt cylinder assembly.

Claims

1. A system for estimating the weight of a payload in a bucket of a machine, the system comprising:

a pivotable lift linkage pivotally attached at a first end to the bucket such that the bucket is pivotable relative to the lift linkage about a first axis;

a lift cylinder assembly connected the lift linkage for pivoting the lift linkage to move the bucket between raised and lowered positions;

a pivotable tilt linkage pivotally connected to the lift linkage and connected to the bucket;

a tilt cylinder assembly connected to tilt linkage for pivoting the tilt linkage such that the bucket pivots relative to the lift linkage about the first axis;

a payload measurement system that receives pressure data relating to a pressure in the lift cylinder assembly and angular position data relating to an angular position of the bucket relative to the first axis, the payload measurement system being configured to estimate weight of a payload in the bucket based on the pressure data, the angular position data and predetermined physical parameters relating to the tilt linkage and lift linkage that are useable to characterize an effect of a portion of the payload that is supported by the tilt cylinder assembly.

2. The system of claim 1 wherein the payload measurement system estimates the weight of the payload in the bucket by determining an initial estimate of the weight of a payload in the bucket based on the pressure data;

determining a tilt compensation that characterizes an effect of a portion of the payload that is supported by the tilt cylinder assembly based on the angular position data and predetermined physical parameters relating to the tilt linkage and the lift linkage; and

adjusting the initial estimate of the weight of the payload in the bucket using the tilt compensation.

3. The system of claim 2 wherein in determining the tilt compensation the payload measurement system is configured to use an estimated bucket weight from a calibration procedure executed by the payload measurement system.

4. The system of claim 2 wherein in determining the tilt compensation the payload measurement system is configured to determine a weight gain with the bucket in a fully racked position.

5. The system of claim 2 wherein in determining the tilt compensation the payload measurement system is configured to determine a tilt compensation gain factor for a particular angular position of the bucket from a table stored in the payload measurement system.

6. The system of claim 1 wherein the angular position data is determined based on an extension of the lift cylinder assembly and an extension of the tilt cylinder assembly.

7. The system of claim 1 wherein the payload measurement system receives tilt cylinder pressure data relating to a pressure in the tilt cylinder assembly and the payload measurement system is configured to use the tilt cylinder pressure data in estimating the weight of the payload in the bucket.

8. The system of claim 2 wherein the payload measurement system determines the initial payload weight estimate from a table stored in the payload measurement system using the pressure data.

9. A method for estimating the weight of a payload in a machine, the machine including a chassis, a bucket, a lift linkage pivotally attached at a first end to the chassis and a second end to the bucket such that the bucket is pivotable relative to the lift linkage about a first axis, a lift cylinder assembly connected to the chassis and the lift linkage for pivoting the lift linkage relative to the chassis, a tilt linkage pivotally connected at a first end to the lift linkage and connected at a second end to the bucket, and a tilt cylinder assembly connected to the chassis and the tilt linkage for pivoting the bucket relative to the lift linkage about the first axis, the method comprising the steps of:

monitoring pressure data relating to a pressure in the lift cylinder assembly;

monitoring angular position data relating to an angular position of the bucket relative to the first axis;

determining an initial estimate of the weight of a payload in the bucket based on the pressure data;

determining a tilt compensation that characterizes an effect of a portion of the payload that is supported by the tilt cylinder assembly based on the angular position data and predetermined physical parameters relating to the tilt linkage and the lift linkage; and

adjusting the initial estimate of the weight of the payload in the bucket using the tilt compensation.

10. The method of claim 9 wherein an estimated bucket weight from a calibration procedure is used in determining the tilt compensation.

11. The method of claim 9 wherein a weight gain with the bucket in a fully racked position is used in determining the tilt compensation.

12. The method of claim 9 wherein a tilt compensation gain factor for a particular angular position of the bucket from a table stored in the payload measurement system is used in determining the tilt compensation.

13. The method of claim 9 wherein the monitoring of the angular position data includes monitoring an extension of the lift cylinder assembly and an extension of the tilt cylinder assembly.

14. The method of claim 9 further including the step of monitoring tilt cylinder pressure data relating to a pressure in the tilt cylinder assembly and the tilt cylinder pressure data is used in determining the tilt compensation.

15. The method of claim 9 wherein determining the initial estimate of the weight of the payload includes looking up the initial weight estimate from a table stored in a payload measurement system using the pressure data.

16. A machine comprising:

a chassis;

a bucket for holding a payload;

a lift linkage pivotally attached at a first end to the bucket such that the bucket is pivotable relative to the lift linkage about a first axis and pivotally attached at a second end to the chassis;

a lift cylinder assembly connected to the chassis and the lift linkage for pivoting the lift linkage relative to the chassis to move the bucket between raised and lowered positions;

a tilt linkage pivotally connected at a first end to the lift linkage and connected at a second end to the bucket;

a tilt cylinder assembly connected to the chassis and to the tilt linkage for pivoting the tilt linkage such that the bucket pivots relative to the lift linkage about the first axis;

a payload measurement system that receives pressure data relating to a pressure in the lift cylinder assembly and angular position data relating to an angular position of the bucket relative to the first axis, the payload measurement system being configured to determine an estimate of the weight of a payload in the bucket based on the pressure data, determine a tilt compensation that characterizes an effect of a portion of the payload that is supported by the tilt cylinder assembly based on the angular position data and predetermined physical parameters relating to the tilt linkage and the lift linkage and adjusts the estimate of the weight of the payload in the bucket using the tilt compensation.

17. The machine of claim 16 wherein in determining the tilt compensation the payload measurement system is configured to use an estimated bucket weight from a calibration procedure executed by the payload measurement system.

18. The machine of claim 16 wherein in determining the tilt compensation the payload measurement system is configured to determine a weight gain with the bucket in a fully racked position.

19. The machine of claim 16 wherein the payload measurement system receives tilt cylinder pressure data relating to a pressure in the tilt cylinder assembly and the payload measurement system is configured to use the tilt cylinder pressure data in estimating the weight of the payload in the bucket.

20. The machine of claim 16 wherein the payload measurement system determines the initial payload weight estimate from a table stored in the payload measurement system using the pressure data.