Excavator Payload Weight Estimation via Hydraulic Torque
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Solution Overview
Problem
Existing load lifting machines, such as excavators, lack effective methods for estimating payload weight, leading to potential overfilling of transportation vehicles, which can cause damage and incur fines, and there is a need for a solution that can be retrofitted to existing machines without inbuilt weight estimation capabilities.
Innovation Solution
A method and apparatus that estimate payload weight by determining torque parameters at various angles of the boom, stick, and load holder, using calibration processes to establish relationships between these parameters and payload weights, and compensating for the torque generated by the acceleration of the center of mass, allowing for accurate weight calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If weight estimation apparatus is added to load lifting machines, then measurement precision of payload weight is improved, but device complexity increases
Solution Approach 1:
The system uses the excavator's own existing components (boom, stick, bucket, hydraulic actuators, and control system) to perform weight estimation. The control system leverages data already being collected for operation control, transforming it into weight information without requiring separate dedicated measurement hardware.
Solution Approach 2:
The patent replaces traditional mechanical weighing systems (such as load cells in the bucket) with a computational approach. By using torque calculations based on hydraulic pressure and actuator position data, the system substitutes physical measurement hardware with mathematical modeling and data processing.
2Measurement precision
If inbuilt weighing apparatus is installed in excavators, then measurement precision is improved, but manufacturing cost and device complexity increase
Solution Approach 1:
The control system performs preliminary data collection during normal operation, storing torque, position, and hydraulic pressure information that will be needed for weight calculations. This prepares the system in advance, so when weight estimation is required, the necessary data is already available without requiring additional installation or setup.
Solution Approach 2:
The control system serves multiple functions: it manages the hydraulic actuators for operation control, collects data for monitoring, and now provides weight estimation. By making the control system multi-functional, the patent eliminates the need for separate dedicated weighing hardware.
3Measurement precision
If torque parameters are determined at multiple linkage geometries, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The control system continuously calculates and stores torque parameters for multiple linkage geometries during normal operation or pre-computes them during calibration phases. This preliminary data collection allows the system to have pre-prepared reference information ready for rapid weight estimation when needed, avoiding time-consuming real-time computations.
Solution Approach 2:
The system dynamically adapts its calculation approach based on the current operational context. During calibration phases, it performs comprehensive multi-geometry measurements to build accurate models. During operation, it uses these pre-built models with real-time sensor data for rapid weight estimation, switching between detailed measurement and quick calculation modes.
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
Enables accurate payload weight estimation in load lifting machines, preventing overfilling and damage, and can be retrofitted to existing machines, providing a reliable and efficient solution for weight calculation.
Implementation Method 1
A first input coupled to the processor for receiving a signal indicative of a torque parameter, being torque or a parameter indicative of torque, between the boom and the chassis during movement of the boom by the hydraulic actuator
Implementation Method 2
determining a first torque parameter being a torque or a parameter indicative of torque between the boom and the chassis during boom movement
Implementation Method 3
determining a second torque parameter being a torque or a parameter indicative of a torque between the boom and the chassis that is generated by acceleration of the centre of mass of the lifting linkage
Data Source
AI summary
A method for estimating weight of a payload held by load lifting machine 1, wherein the load lifting machine comprises lifting linkage with a boom 5 pivotably connected to a machine chassis 2, the method comprising calculating an estimation using the torque of the boom 5, torque of the boom during calibration lifts for first and second payloads, and dynamic torque adjustment determined for first and second payloads.