Excavator Hydraulic Boom Control for Accurate Bucket Pressing Force
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Solution Overview
Problem
Existing hydraulic drive apparatuses for excavation machines struggle to accurately control the pressing force of the bucket against the construction surface, as the pressing force is influenced by the posture of the work device, leading to imprecise control of the compaction force.
Innovation Solution
A hydraulic drive apparatus with a controller that calculates and adjusts the target boom cylinder speed based on the detected posture and load information, using sensors to determine the actual pressing force and center-of-gravity position, and corrects the speed to maintain a target pressing force, ensuring accurate control of the construction surface and pressing force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the cylinder thrust of the boom cylinder is used as the compaction force, then the control system is simple, but the pressing force accuracy deteriorates because the pressing force changes with the posture of the work device
Solution Approach 1:
The control system calculates the pressing force by combining the boom cylinder thrust with the gravitational force acting on the work device, creating a feedback mechanism that compensates for posture variations. This allows the system to maintain accurate pressing force control regardless of the work device's position or orientation
Solution Approach 2:
The system changes the calculation parameters from simply using cylinder thrust to using a composite parameter that includes both cylinder thrust and gravitational force components. This parameter transformation enables accurate pressing force measurement across different postures without requiring complex additional sensors
2Measurement precision
If the pressing force control is improved by considering work device posture, then the pressing force accuracy is improved, but the device complexity increases due to additional calculations and sensors
Solution Approach 1:
The control system performs multiple functions using existing components: it simultaneously controls the hydraulic cylinders for movement while also calculating pressing force by incorporating gravitational force data. This multi-functionality approach avoids adding dedicated sensors or separate control systems, thereby limiting complexity increase
Solution Approach 2:
The control system uses its own existing data (cylinder thrust measurements and posture information) to calculate the pressing force, making the system self-sufficient. No external sensors or additional measurement devices are required, as the control unit itself performs the comprehensive calculation
Data Source
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AI summary
Provided is a hydraulic drive apparatus capable of precisely performing control of making a construction surface by a bucket closer to a target construction surface and making a pressing force by which the bucket is pressed against the construction surface closer to a target pressing force. The hydraulic drive apparatus includes a boom flow rate control valve (36), a target boom cylinder speed calculation part, a pressing force calculation part, a correction part, and a boom flow rate operation part. The target boom cylinder speed calculation part calculates a target boom cylinder speed for making the construction surface by the bucket closer to the target construction surface. The pressing force calculation part calculates the pressing force by which the bucket is pressed against the construction surface, based on the cylinder thrust of the boom cylinder (26) and the center-of-gravity position information on the center-of-gravity position of the work device. The correction part corrects the target boom cylinder speed to make the deviation between the target pressing force and the calculated pressing force closer to 0. The boom flow rate operation part operates the boom flow rate control valve (36) to provide the corrected target boom cylinder speed.