Work Machine Controller Velocity Limiting for Compaction Work
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Solution Overview
Problem
Existing hydraulic excavator technologies struggle to accurately determine the work phase, leading to inappropriate velocity limitations during compaction work, which can result in the bucket claw tip penetrating into the design surface, damaging the intended surface.
Innovation Solution
A work machine equipped with a controller that determines the work phase based on the bucket's posture relative to the design surface, adjusting the limiting velocity accordingly to prevent penetration during compaction work by using a posture-based determination system and velocity correction coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the velocity limitation is relaxed or cancelled based on boom operation signal during compaction work, then compaction work capability is improved, but the bucket claw tip penetrates into the design surface causing surface damage
Solution Approach 1:
The system changes the velocity limitation parameter dynamically based on the detected work phase. When compaction work is detected through posture analysis, the velocity limitation is relaxed or cancelled to enable effective compaction. When finishing work is detected, the velocity limitation is maintained to prevent surface damage. This parameter change resolves the contradiction by adapting the velocity constraint to the specific work phase.
Solution Approach 2:
The system continuously monitors the bucket posture and provides feedback to determine the work phase. This feedback mechanism allows the control system to distinguish between compaction work and finishing work, enabling appropriate velocity limitation adjustments. The feedback loop ensures that velocity limitations are applied correctly based on actual work conditions, preventing both surface damage and enabling effective compaction.
2Manufacturing precision
If the velocity at which the work device moves toward the design surface is set lower near the design surface, then the control point is kept onto the design surface, but the force of pushing the back surface of the bucket against the ground weakens
Solution Approach 1:
The velocity limitation is made dynamic rather than static. The system adjusts the velocity constraint based on the detected work phase through posture analysis. During compaction work, the velocity limitation is relaxed to allow higher velocities and stronger compaction forces. During finishing work, the velocity limitation is applied to maintain precise control point positioning. This dynamic adjustment resolves the contradiction between positioning accuracy and compaction force.
3Device complexity
If the work phase is determined only by the boom operation signal, then the determination process is simplified, but the work phase determination becomes inaccurate leading to inappropriate velocity limitations
Solution Approach 1:
The system adds a new dimension to work phase determination by incorporating bucket posture analysis in addition to boom operation signals. The posture dimension provides critical information about whether the bucket is in a compaction position or finishing position. This multi-dimensional approach improves determination accuracy without significantly increasing system complexity, as the posture data is derived from existing sensors.
Data Source
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AI summary
A controller mounted in a work machine limits a velocity at which a work device approaches a design surface to be equal to or lower than a predetermined limiting velocity in such a manner that the work machine is located above the design surface when an operation device is operated. The controller determines whether a work phase of the work device is compaction work on the basis of a posture of a bucket with respect to the design surface in a case in which the operation device instructs the work device to approach the design surface, and sets the limiting velocity when determining that the work phase of the work device is the compaction work to be higher than the limiting velocity when determining that the work phase of the work device is other than the compaction work.