Excavator Bucket Mass Calculation Using Boom Deflection and Rope Force
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Solution Overview
Problem
Current methods for accurately calculating the mass of material in excavating machine buckets, such as electrical parameter methods, hybrid structural methods, and direct loadcell measurement methods, are either inaccurate or require complex and expensive equipment, which is challenging to maintain, especially in harsh environments, and do not meet the desired accuracy standards for autonomous haul fleets.
Innovation Solution
A method and system that uses a controller to receive distance data from a distance sensor and torque data from a torque sensor to calculate the frontend geometry and rope force of the excavating machine, allowing for accurate calculation of the mass of material in the bucket using equations that account for crowd and bail angles, and inertial corrections, without the need for battery-powered loadcells and telemetry in the bucket.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct loadcell measurement methods are used to achieve accurate mass calculations, then measurement precision is improved, but device complexity and maintenance difficulty increase due to battery-powered equipment in harsh environments
Solution Approach 1:
The patent extracts the measurement function from the bucket environment by placing sensors on the stationary boom structure. The load cell measures boom deflection, and the distance sensor measures bucket position, both from a protected location rather than exposing equipment to harsh conditions in the bucket.
Solution Approach 2:
The patent uses the boom itself as an intermediary mechanical element that transmits the load information from the bucket to the measurement point. The boom's elastic deflection under load serves as a passive transmission medium, eliminating the need for active measurement equipment in the bucket.
2Measurement precision
If hybrid structural methods with strain gauges on A-Frame legs are used, then measurement precision improves to within fifteen percent, but ease of operation deteriorates due to difficulty in calibration
Solution Approach 1:
The patent replaces the complex calibration-dependent strain gauge system with a physics-based calculation approach. Instead of relying on calibrated mechanical sensors, the system uses measured boom deflection and bucket position to calculate mass through equations of equilibrium, eliminating the calibration step.
3Device complexity
If electrical parameter methods are used to calculate loads, then device complexity is reduced, but measurement precision deteriorates with twenty to thirty percent variations
Solution Approach 1:
The patent replaces electrical parameter measurements with direct mechanical measurement of boom deflection using a load cell. This mechanical approach directly measures the physical quantity of interest (force) rather than inferring it from electrical parameters, achieving both simplicity and accuracy.
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
This solution provides accurate mass calculations with reduced equipment complexity and maintenance costs, enhancing productivity by improving load accuracy and reducing bottlenecks and truck fatigue, while maintaining high accuracy standards for autonomous haul fleets.
Implementation Method 1
a distance sensor mounted on the excavating machine and a target positioned on an arm of the excavating machine
Implementation Method 2
torque data for a rotating hoist drive shaft in the excavating machine. The torque data is generated by a torque sensor positioned about the shaft
Implementation Method 3
By combining the suspended load measurement with a direct measurement of the acceleration of the suspended mass, Newton's second law of motion can be directly applied, leading to an accurate, inertially compensated mass measurement
Data Source
AI summary
An aspect of the present disclosure provides a method for calculating the mass of material in an excavating machine bucket including receiving, by a controller, distance data. The distance data is the distance between a distance sensor mounted on the excavating machine and a target positioned on an arm of the excavating machine. Moreover, the method includes receiving torque data for a rotating hoist drive shaft in the excavating machine. The torque data is generated by a torque sensor positioned about the shaft. Furthermore, the method includes calculating frontend geometry of the excavating machine. The excavating machine includes at least one rope. Additionally, the method includes calculating a rope force in the at least one rope using the torque data and calculating the mass of material in the excavating machine bucket using the calculated frontend geometry and the rope force.