Work Machine Satellite Masking for Implement-Induced Positioning Errors
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Solution Overview
Problem
Hydraulic excavators face positioning errors due to diffracted waves from the front work implement interfering with satellite signal reception, leading to reduced precision and reproducibility in positioning results, especially when the posture of the implement changes during operations.
Innovation Solution
A work machine equipped with a controller that computes the position of the upper swing structure and work implement using satellite signals, employs posture sensors to detect the implement's posture, and sets a mask range to exclude interfering satellites, ensuring precise positioning by selecting only reliable satellites for computation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the front work implement is positioned above the positioning antenna during operation, then the work machine can perform excavation and dumping operations, but the positioning signal reception is interfered with by diffracted waves, leading to reduced positioning precision
Solution Approach 1:
The patent extracts and excludes interfering satellites from the positioning computation by identifying satellites whose signals are diffracted by the front work implement. The controller separates reliable satellites from unreliable ones based on geometric relationships between the antenna, implement, and satellites, then performs positioning computation using only the reliable satellites.
Solution Approach 2:
The patent changes the parameter set used for positioning computation by dynamically selecting which satellites to include based on the current posture of the work implement. The system adjusts the satellite selection parameters according to real-time geometric conditions, switching between different sets of available satellites to maintain positioning accuracy.
2Adaptability or versatility
If the posture of the front work implement changes during operation, then the work machine can adapt to different work requirements, but the combination of positioning satellites changes, leading to reduced reproducibility of positioning results
Solution Approach 1:
The patent implements a dynamic satellite selection mechanism that continuously adapts to changing work implement postures. The controller recalculates which satellites are reliable based on the current geometric relationship between the antenna, implement, and satellites, ensuring consistent positioning methodology regardless of posture changes.
Solution Approach 2:
The system uses feedback from posture sensors to continuously monitor the work implement's position and adjusts the satellite selection accordingly. This closed-loop approach ensures that the same positioning methodology is applied consistently across different postures, improving reproducibility.
3Measurement precision
If electromagnetic wave absorbers are installed on the upper structure to prevent signal reflection, then positioning precision is improved, but diffracted waves from the front work implement still interfere with signal reception
Solution Approach 1:
The patent introduces an intermediary computational step that identifies and filters out signals from satellites affected by diffraction. Rather than trying to prevent diffraction physically, the system uses geometric analysis as an intermediary to distinguish between direct and diffracted signals, then excludes the latter from computation.
Data Source
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AI summary
A controller sets, as a satellite mask range, a range for which a work implement can become an obstacle when an antenna receives positioning signals from a plurality of positioning satellites on the basis of a position at which the antenna is installed, a movable range of the work implement, a posture of an upper swing structure, and an azimuth angle of the upper swing structure. The controller cancels the setting of the satellite mask range in a case where it has been determined, on the basis of satellite positioning condition data acquired from a receiver, that the setting of the satellite mask range leads to reduced precision of positioning computation by the receiver. In a case where the setting of the satellite mask range has been canceled, the receiver computes the position of the upper swing structure on the basis of the positioning signals transmitted from the plurality of positioning satellites.