Wheel Loader Bucket Load Calculation via Lift Arm Sensors
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Solution Overview
Problem
Existing load measurement methods for hydraulic excavators cannot be directly applied to wheel loaders due to differences in their mechanical configurations, specifically the use of lift arm and bucket cylinders, which hinders accurate load calculation on the bucket.
Innovation Solution
A wheel loader system incorporating a lift arm angle sensor, pressure sensors, and a control device that calculates the load on the bucket by determining unloaded and loaded moments around the hinge pin using detected pressures and angles, along with stored vehicle body information, allowing for accurate load determination without requiring pressure sensors on the bucket cylinder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If load measurement method for hydraulic excavator is applied to wheel loader, then load calculation can be performed, but measurement accuracy deteriorates due to different mechanical configurations
Solution Approach 1:
The patent changes the measurement parameters from boom cylinder pressure (excavator) to lift arm cylinder pressure (wheel loader). The calculation formula is adapted to use the pressure of the lift arm cylinder, the angle of the lift arm, and the weight and center of gravity of the bucket to compute the load, making the measurement accurate for wheel loader's specific mechanical configuration
Solution Approach 2:
The patent segments the measurement system into distinct components specific to wheel loader: lift arm angle sensor, lift arm cylinder pressure sensor, and separate calculation of unloaded moment and loaded moment. This segmentation allows each component to be optimized for the wheel loader's unique kinematics and loading characteristics
2Measurement precision
If pressure sensor is installed on bucket cylinder, then load measurement becomes possible, but device complexity increases
Solution Approach 1:
The patent uses the lift arm cylinder pressure as an intermediary measurement point instead of directly measuring bucket cylinder pressure. The lift arm cylinder's pressure, combined with lift arm angle data, serves as a proxy to calculate the bucket load through moment equilibrium equations, eliminating the need for direct bucket cylinder sensing
Solution Approach 2:
The patent extracts the load measurement capability from the bucket cylinder pressure sensor and relocates it to the lift arm cylinder pressure sensor. This extraction simplifies the system by using an existing pressure sensor location and eliminating the need for additional sensors on the bucket cylinder
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 precise calculation of the load on the bucket using the lift arm cylinder pressure and angle data, eliminating the need for pressure sensors on the bucket cylinder and simplifying the initial learning process, thus improving operational efficiency and accuracy.
Implementation Method 1
a lift arm angle sensor that detects an angle of the lift arm
Implementation Method 2
a pressure sensor that detects a pressure of the lift arm cylinder
Implementation Method 3
the control device calculates a load on the bucket by determining unloaded and loaded moments around the hinge pin using detected pressures and angles
Data Source
Figure 1
Figure 2
Figure 3
AI summary
In an unloaded state of the bucket (3), a control device (30) calculates an unloaded moment (M0) around a hinge pin G from the pressure of the lift arm cylinder that is detected by pressure sensors (15a, 15b), the angle of a lift arm that is detected by a lift arm angle sensor 14, and dimension data extracted from a vehicle body information database (35). In a loaded state of the bucket, the control device calculates a loaded moment (M1) around the hinge pin G from the pressure of the lift arm cylinder, the angle of the lift arm, and the dimension data extracted from the vehicle body information database. The control device calculates the load (W) on the bucket by dividing the difference between the unloaded moment and the loaded moment by the horizontal distance (Lw) between the hinge pin and the gravity center position of the bucket.