Excavator Depth Control Based on Soil Hardness and Stall Risk
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Solution Overview
Problem
Conventional shovels reduce excavation efficiency by minimizing soil intake to avoid bucket stalling, leading to suboptimal excavation performance due to inadequate depth control and soil hardness assessment.
Innovation Solution
A shovel system equipped with sensors and a control device that calculates a target excavation depth based on soil hardness, adjusting the boom and bucket operations to optimize excavation efficiency without risking bucket immobilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the shovel increases excavation depth to improve excavation efficiency, then the excavation volume increases, but the bucket may get stuck and stall
Solution Approach 1:
The control device performs preliminary assessment of soil hardness before excavation using sensors (load cell, posture sensors) and pre-calculates the appropriate excavation depth based on predicted excavation reaction forces. This preliminary action allows the system to set safe excavation depth limits in advance, preventing bucket stalling while maximizing excavation efficiency.
Solution Approach 2:
The system continuously monitors excavation reaction forces during operation using load cells and posture sensors, comparing actual forces against predicted thresholds. When the excavation reaction force approaches the predicted value, the control device automatically raises the boom to prevent bucket stalling. This closed-loop feedback mechanism dynamically adjusts excavation depth to maintain optimal efficiency while preventing stalling.
2Reliability
If the shovel reduces excavation depth to prevent bucket stalling, then the reliability improves, but the excavation efficiency decreases
Solution Approach 1:
The system dynamically changes the excavation depth parameter based on real-time soil hardness assessment and excavation reaction force monitoring. Instead of using a fixed conservative depth, the control device adjusts the target excavation depth according to actual soil conditions, allowing deeper excavation in softer soils and shallower excavation in harder soils. This parameter adaptation resolves the contradiction by optimizing depth for each specific condition.
Solution Approach 2:
The system transitions from static, predetermined excavation depth settings to dynamic, real-time depth adjustment. The control device continuously monitors excavation reaction forces and automatically adjusts the boom position and excavation depth during operation. This dynamic approach allows the system to maximize excavation depth when conditions permit while preventing stalling when reaction forces increase, thereby resolving the efficiency-reliability contradiction.
3Reliability
If the shovel uses automatic boom raising based on excavation reaction force, then the bucket stalling is avoided, but the excavation depth is reduced unnecessarily
Solution Approach 1:
The system performs preliminary assessment of soil hardness and predicts excavation reaction forces before actual excavation begins. Based on these predictions, the control device pre-calculates the appropriate excavation depth and sets target depth limits. This preliminary action allows the system to maintain optimal excavation depth throughout the operation rather than unnecessarily reducing depth, resolving the contradiction between stalling avoidance and depth utilization.
Solution Approach 2:
The system uses feedback from load cells and posture sensors to monitor actual excavation reaction forces during operation. The control device compares real-time forces against predicted thresholds and only raises the boom when forces approach the predicted stalling threshold. This precise feedback control prevents unnecessary boom raising while still avoiding bucket stalling, thereby maintaining optimal excavation depth and efficiency.
Data Source
AI summary
A shovel includes a lower traveling body, an upper turning body mounted on the lower traveling body, an attachment attached to the upper turning body, and a control device mounted on the upper turning body and configured to assist an excavating motion with the attachment. The control device is configured to derive a target excavation depth based on the hardness of an excavation target.