Wheel Loader Load Measurement Using Boom Force and Ground Acceleration
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Solution Overview
Problem
Existing methods for estimating the loaded weight in a work machine bucket are inaccurate when loads other than those listed are present, and are affected by vehicular body vibrations during travel.
Innovation Solution
A work machine system comprising a running wheel, machine main body, boom, bucket, and actuator, with a controller that calculates load mass using thrust of the actuator and ground acceleration to compensate for vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a list showing relation between boom angle and bottom pressure is used to estimate loaded weight, then the estimation method is simple to implement, but the estimation accuracy deteriorates when loads other than those in the list are present
Solution Approach 1:
The patent replaces the mechanical lookup-table-based estimation method with a calculation method using Newton's second law. Instead of relying on pre-defined relationships between boom angle and bottom pressure, the system calculates load weight using the formula: load weight = (actuator thrust - bucket weight - arm weight) / gravity - (arm mass moment of inertia × angular acceleration) / (gravity × load arm length). This substitution of physical principle enables accurate estimation for any load type while maintaining implementation simplicity through standard sensor data.
Solution Approach 2:
The patent changes the parameters used for estimation from static lookup tables to dynamic parameters including actuator thrust, angular acceleration, and moment of inertia. By incorporating real-time dynamic parameters rather than relying on pre-defined static relationships, the system achieves accurate estimation across varying load conditions while keeping the calculation process straightforward.
2Device complexity
If bottom pressure measurement is used to estimate load weight, then the measurement system is simple, but the measurement precision deteriorates during travel due to vehicular body vibrations
Solution Approach 1:
The patent replaces the direct bottom pressure measurement approach with a dynamic calculation method based on Newton's second law. The system uses actuator thrust, angular acceleration, and moment of inertia to calculate load weight, eliminating the sensitivity to vehicular vibrations that plagues bottom pressure-based methods. This substitution maintains relatively simple system requirements while dramatically improving measurement precision during travel.
Solution Approach 2:
The patent extracts the load weight calculation from the vibration-prone bottom pressure measurement system. By separating the load weight determination from the bottom pressure signal and instead using actuator thrust and angular acceleration data, the system removes the harmful influence of vehicular body vibrations from the measurement process.
3Measurement precision
If calibration corrections are applied to compensate for vibrations, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The patent replaces complex calibration correction procedures with a fundamental physics-based calculation approach. By using Newton's second law directly to calculate load weight from actuator thrust and angular acceleration, the system achieves vibration compensation without requiring additional calibration steps or complex correction algorithms, thereby maintaining measurement precision while avoiding increased system complexity.
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
Accurately estimates the mass of the load within the bucket during travel by considering ground accelerations and vibrations, eliminating the need for calibration corrections.
Implementation Method 1
A mass of a load within the bucket is calculated based on thrust of the actuator and a ground acceleration of the work machine
Data Source
AI summary
A running wheel is attached to a machine main body. A boom is attached to the machine main body. A bucket is attached to the boom. A boom cylinder is attached to the machine main body and drives the boom. A controller calculates a mass of a load within the bucket based on boom cylinder force of the boom cylinder and a ground acceleration of a wheel loader.