GNSS Azimuth Correction for Construction Machine Swing Stability
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Solution Overview
Problem
Hydraulic excavators with GNSS positioning using two antennas face precision issues in calculating the azimuth of the upper swing structure due to postural changes like raising and lowering of the front work implement, leading to unstable operation and reduced work efficiency, as the technology cannot effectively handle satellite signal interruptions and unbalanced satellite arrangements.
Innovation Solution
A construction machine equipped with a GNSS system, angular velocity acquiring apparatus, machine-body posture angle acquiring apparatus, and front-implement posture angle acquiring apparatus, which uses a controller to compute and correct the azimuth of the upper swing structure by removing gyro bias and determining the quality of the azimuth based on posture angles, ensuring accurate positioning regardless of postural changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two GNSS antennas are used for positioning, then positioning functionality is provided, but azimuth calculation precision deteriorates due to unbalanced satellite arrangement when front work implement raises and lowers
Solution Approach 1:
The patent introduces a third GNSS antenna as an intermediary element to mediate between the two original antennas. This third antenna provides additional satellite signal reception paths, enabling the system to select optimal antenna combinations that maintain balanced satellite geometry even when the front work implement changes posture. The controller dynamically selects which antennas to use based on current satellite arrangement quality, thus preserving azimuth calculation precision while maintaining positioning functionality.
2Productivity
If front work implement raises and lowers during operation, then excavation work is performed, but satellite signal reception becomes unbalanced causing azimuth calculation to vary
Solution Approach 1:
The patent implements a dynamic antenna selection mechanism where the controller continuously monitors satellite signal reception quality from multiple antennas and adaptively selects the optimal antenna combination based on current operating conditions. As the front work implement raises and lowers, changing the spatial arrangement and satellite visibility, the system dynamically adjusts which antennas are active, ensuring stable azimuth calculation throughout the excavation cycle.
Solution Approach 2:
The system changes the operational parameters of the GNSS system by switching between different antenna configurations based on satellite geometry quality. When the front work implement changes posture, the controller evaluates satellite arrangement parameters and transitions between antenna combinations to maintain optimal signal reception geometry, thereby preserving azimuth calculation stability during dynamic excavation operations.
3Reliability
If RTK positioning is implemented with two antennas, then correction data can be received, but azimuth calculation becomes unreliable when satellite capture is insufficient
Solution Approach 1:
Instead of using exactly two antennas for RTK positioning, the patent employs three antennas, providing excessive redundancy. This allows the system to select partial combinations of antennas (e.g., using only the two best-receiving antennas at any given moment) while having backup options available. When satellite capture is insufficient with one antenna pair, the system can switch to another pair, ensuring continuous reliable azimuth calculation while maintaining RTK positioning capability.
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
The solution enables accurate and robust calculation of the upper swing structure's azimuth, reducing the frequency of operation suspension and enhancing work efficiency by compensating for postural changes and satellite signal interruptions.
Implementation Method 1
a GNSS system 17 having two GNSS antennas 17a and 17b attached to the upper swing structure 2, and a GNSS receiver 17c that calculates three-dimensional coordinates of the GNSS antennas and an azimuth of the upper swing structure on a basis of a satellite signal received by the GNSS antennas
Implementation Method 2
an angular velocity acquiring apparatus 13 that is attached to the upper swing structure 2, and acquires an angular velocity of the upper swing structure
Implementation Method 3
a machine-body posture angle acquiring apparatus 13 that is attached to the upper swing structure 2, and acquires a posture angle of the upper swing structure
Implementation Method 4
execute a bias removal computation of removing a gyro bias from the angular velocity of the upper swing structure acquired at the angular velocity acquiring apparatus on a basis of a result of the determination about the quality of the azimuth
Data Source
AI summary
A position/posture computing section determines that an azimuth of an upper swing structure calculated at a GNSS receiver is of low quality when at least one of a posture angle of the upper swing structure acquired at a machine-body IMU and a posture angle of a front work implement acquired at a boom IMU is equal to or larger than a threshold value, executes a bias removal computation on the basis of the quality of the azimuth and the azimuth of the upper swing structure calculated at the GNSS receiver, calculates a corrected azimuth of the upper swing structure on the basis of the azimuth of the upper swing structure calculated at the GNSS receiver, and an angular velocity of the upper swing structure from which a gyro bias has been removed, and computes a three-dimensional position and posture of the front work implement by using the corrected azimuth.