Excavator Payload Weight Calculation via Load Cell Moment Analysis

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Solution Overview

Problem

Current methods for calculating payload weight in excavator buckets are inaccurate, leading to underloading or overloading issues, which decrease productivity and risk equipment damage, as they fail to provide real-time weight measurements before delivery and assume incorrect centers of gravity.

Innovation Solution

A system comprising sensors to measure loads on hydraulic rams and a calculating device that determines payload weight by summing moments and calculating the center of gravity based on stroke measurements from these sensors, providing accurate weight calculations and alerts for overload conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If payload weight is calculated using assumed center of gravity, then calculation can be performed, but measurement precision deteriorates due to errors when actual payload position differs from assumed position

Engineering Contradiction:
ImproveproductivityVSAvoidpayload weight measurement precision
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent replaces the traditional mechanical assumption-based center of gravity calculation with a sensor-based measurement system. Load cells mounted on the excavator bucket measure actual forces, and stroke sensors measure actual positions, substituting the mechanical assumption model with direct physical measurement to achieve accurate payload weight calculation regardless of payload position.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates a multi-functional system that simultaneously measures payload weight, determines center of gravity position, and monitors loading conditions. The load cells and stroke sensors serve multiple purposes: calculating weight, positioning the center of gravity, and detecting overload or underload conditions, making the system universally applicable for various monitoring needs.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Device complexity

If no real-time weight measurement is provided before delivery, then system complexity is reduced, but loss of information increases as user cannot determine loading status

Engineering Contradiction:
Improvesystem complexityVSAvoidpayload weight information
Core Design Contradiction:
Device complexityVSLoss of information

Solution Approach 1:

The patent implements a feedback system where load cells and stroke sensors continuously measure loading conditions, the calculating device processes this data to determine payload weight and center of gravity position, and this information is fed back to the operator in real-time. This closed-loop feedback provides continuous weight information without requiring complex additional hardware beyond the sensing and calculation components.

Inventive Principle:
Principle #23Feedback

3Reliability

If payload weight is overestimated, then equipment damage risk is reduced, but productivity decreases due to underloading requiring additional trips

Engineering Contradiction:
Improveequipment protectionVSAvoidproductivity
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent performs preliminary measurement and calculation of payload weight and center of gravity position before the delivery operation. By knowing the exact weight and position in advance, the operator can optimize loading to achieve full capacity without exceeding limits, preventing both underloading (which would require additional trips) and overloading (which would risk equipment damage).

Inventive Principle:
Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system enables precise payload weight calculation, preventing underloading or overloading, enhancing productivity by ensuring accurate delivery and reducing equipment damage, while also estimating fatigue life and monitoring loading states for downstream devices.

Implementation Method 1

a calculating device configured to calculate the payload weight being carried by the lifting machine based on the first load and the second load... calculate a centre of gravity of the payload, from relationships obtained by summing moments about a first point and a second point

Methodology Applied
Scientific EffectMoment of Inertia: Moment of Inertia

Data Source

PatentEP3237854B1A system and method of calculating a payload weight
Publication Date: 2024.06.05 CQMS PTY LTD
  • EP3237854B1 patent drawingFigure 1
  • EP3237854B1 patent drawingFigure 2
  • EP3237854B1 patent drawingFigure 3

AI summary

A system of calculating a payload weight, the system including: a first sensor configured to measure a first load associated with a first member of a lifting machine; a second sensor configured to measure a second load associated with a second member of the lifting machine; and a calculating device configured to calculate the payload weight being carried by the lifting machine based on the first load and the second load.