Method and system for estimating payload weight with tilt position compensation

• US 9,464,403 B2
• Filed: 06/09/2014
• Issued: 10/11/2016
• Est. Priority Date: 06/09/2014
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Shatters, Aaron
• Primary Examiner(s): Gibson, Randy W
• Application Number:
  US14/299,402
• Publication Number:
  US 20150354177A1
• Time in Patent Office: 855 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 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,

wherein an estimated bucket weight is used in determining the tilt compensation based on the following formulas;

2. The method of claim 1 wherein a weight gain with the bucket in a fully racked position is used in determining the tilt compensation, wherein the weight gain is based on the following formula:

3. The method of claim 1 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, wherein the tilt compensation gain is based on the following formulas:

4. The method of claim 1 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.

5. The method of claim 1 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.

6. The method of claim 1 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.