Excavator Controller Dragging Prevention via Velocity Vector Correction
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Solution Overview
Problem
Existing hydraulic excavators face efficiency issues due to dragging when operating on slippery surfaces or encountering excavation obstacles, which disrupts semiautomatic control and requires skillful operator adjustments to prevent machine body dragging.
Innovation Solution
A work machine with a controller that calculates a target velocity vector to maintain the work device's position on the construction surface and corrects the direction of this vector upward when dragging is detected, preventing machine body dragging without stopping the arm cylinder during area restriction control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressure of the arm cylinder is restricted to prevent machine body dragging, then dragging is prevented, but the semiautomatic operation is interrupted and operator's operability is lowered
Solution Approach 1:
The controller dynamically adjusts the target velocity of the work device based on the detected dragging state. When dragging is detected, the controller changes the velocity parameter from the originally calculated target velocity to a reduced velocity, allowing continuous operation while preventing dragging. This parameter adaptation enables the system to maintain semiautomatic operation without interruption.
2Productivity
If the excavation force is increased to improve productivity, then excavation efficiency is improved, but the machine body is dragged on slippery surfaces
Solution Approach 1:
The system continuously monitors the actual velocity of the work device and compares it with the target velocity to detect dragging conditions. When the actual velocity deviates from the target velocity indicating dragging, the controller receives feedback and adjusts the target velocity accordingly, enabling continuous excavation while maintaining machine body stability.
Solution Approach 2:
The controller dynamically adjusts the target velocity parameter based on real-time dragging detection. Instead of using a fixed velocity limit, the system adapts the velocity parameter continuously during operation, allowing the excavation force to be optimized for productivity while automatically reducing velocity when dragging conditions are detected to maintain stability.
Data Source
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AI summary
In a hydraulic excavator including a main controller that can execute area restriction control, the main controller is configured to calculate an operation velocity Vfx of a front work device in a machine body coordinate system and a movement velocity (dragging velocity) Vu of a machine body in a gravity coordinate system and correct a direction of a calculated target velocity vector Vt upward away from a construction target surface when generation of dragging is detected during execution of the area restriction control based on the calculated operation velocity Vfx of the front work device 2 and the calculated movement velocity Vu of the machine body.