Excavator Boom Lowering Control for Smooth Compaction Transitions
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Solution Overview
Problem
Existing machine control systems for hydraulic excavators experience significant velocity differences during boom lowering operations, leading to shocks and uncomfortable operating conditions, making it difficult to distinguish between leveling and compaction work, resulting in inefficient operations and operator fatigue.
Innovation Solution
A controller that calculates a weighted average of limiting velocities for the boom cylinder based on the boom lowering operation amount and distance to the target surface, smoothly transitioning between velocities to prevent sudden changes and ensure intended compaction work without shocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the limiting velocity is switched between first limiting velocity information (for compaction control) and second limiting velocity information (for leveling control) based on work determination, then compaction work can be performed, but significant velocity differences cause shock in the machine body and uncomfortable operation feelings
Solution Approach 1:
The patent changes the parameter of limiting velocity from discrete switched values to continuously adjustable values. The limiting velocity is calculated based on the ratio of actual boom lowering operation amount to predetermined operation amounts, creating a continuous spectrum of velocity limits rather than abrupt switches between compaction and leveling velocities. This resolves the contradiction by allowing the system to adapt to different work types while maintaining smooth velocity transitions that prevent shock and improve operator comfort.
Solution Approach 2:
The patent introduces dynamic adjustment of the limiting velocity based on real-time operation amount ratios. Instead of static velocity limits for compaction and leveling work, the system dynamically calculates the limiting velocity as a proportion of the difference between first and second limiting velocities, weighted by the operation amount ratio. This dynamic approach allows smooth transitions between work types and eliminates abrupt velocity changes that cause shock.
2Adaptability or versatility
If the compaction determination condition is relaxed to enable compaction work, then compaction can be performed, but velocity limitation control based on second limiting velocity information is executed in unintended situations, reducing work efficiency
Solution Approach 1:
The patent changes the determination criterion from a fixed compaction determination condition to a continuous operation amount ratio parameter. The limiting velocity is determined by the ratio of actual boom lowering operation amount to predetermined operation amounts, allowing precise differentiation between compaction intent and normal leveling operations. This resolves the contradiction by enabling compaction work while preventing erroneous velocity limitation in non-compaction situations, thereby maintaining work efficiency.
3Measurement precision
If the compaction determination condition is made stricter to prevent unintended compaction control, then operation accuracy improves, but compaction work cannot be executed when desired by the operator
Solution Approach 1:
The patent introduces a dynamic operation amount ratio parameter that continuously adjusts based on the operator's boom lowering input. This dynamic parameter allows the system to accurately distinguish between compaction and leveling intentions while remaining responsive to operator commands. The limiting velocity is adjusted proportionally based on this ratio, ensuring that compaction work can be executed when desired while maintaining high determination accuracy through continuous monitoring of operation amounts.
4Speed
If sudden velocity changes occur during boom lowering operations, then control responsiveness improves, but shock occurs in the machine body and operator fatigue increases
Solution Approach 1:
The patent applies beforehand cushioning by pre-calculating and gradually applying velocity limitations based on the operation amount ratio. Instead of abruptly imposing velocity limits that cause shock, the system gradually adjusts the limiting velocity as a proportion of the difference between compaction and leveling velocities. This cushioning approach maintains control responsiveness while preventing sudden velocity changes that cause shock and operator fatigue.
Solution Approach 2:
The patent makes the velocity limitation dynamic and proportional to the operation amount ratio. The limiting velocity is calculated as a dynamic value that smoothly transitions between compaction and leveling velocities based on real-time operation inputs. This dynamic approach maintains responsive control while eliminating sudden velocity changes, thereby preventing shock and reducing operator fatigue.
Data Source
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AI summary
A controller outputs a first velocity (first limiting velocity) as a limiting velocity for a boom cylinder when a boom lowering operation amount is smaller than a first operation amount, and outputs a second velocity when the boom lowering operation amount is equal to or larger than the first operation amount. The first velocity is set to decrease according to a decrease in a target surface distance. The second velocity is defined by a weighted average of the first velocity and a third velocity (second limiting velocity) set to change according to one of the target surface distance and the boom lowering operation amount of the operation device, and is set such that an increase in the boom lowering operation amount reduces a weight for the first velocity while increasing a weight for the third velocity.