Hydraulic Excavator Cylinder Control for Stroke-End Impact Stability
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Solution Overview
Problem
Existing hydraulic excavator systems fail to effectively utilize the impact generated when a cylinder collides with a stroke end without compromising the machine's dynamic stability, limiting the ability to perform certain operations that rely on this impact.
Innovation Solution
A work machine with a drive control system that predicts the trajectory of the dynamic center of gravity position and adjusts the cylinder's allowable velocity to ensure collision with the stroke end generates an impact without destabilizing the machine by incorporating a stroke end distance calculation, dynamic center of gravity prediction, and allowable velocity changing mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the cylinder is allowed to collide with the stroke end at high velocity to generate impact for work operations, then the workability and operability are improved, but the machine may lose balance and tip due to the impact
Solution Approach 1:
The control system dynamically adjusts the cylinder velocity based on real-time stability assessment. The ECU calculates the distance from the dynamic center of gravity to the tipping line and modifies the allowable velocity accordingly, allowing high velocity when stable and reducing velocity when instability risk increases, thus resolving the contradiction between workability and stability
Solution Approach 2:
The system changes the parameter of allowable cylinder velocity based on the calculated stability margin. When the distance from the dynamic center of gravity to the tipping line is large, a higher velocity is permitted; when the distance decreases, the velocity is reduced. This parameter adjustment resolves the contradiction by adapting velocity to stability conditions
2Stability of the object's composition
If deceleration control is performed to mitigate impact and maintain stability, then the machine stability is improved, but the ability to perform work operations that require impact is reduced
Solution Approach 1:
The control system transitions from static deceleration control to dynamic velocity management. Instead of always decelerating near the stroke end, the system calculates real-time stability margins and adjusts velocity accordingly, enabling impact-based work operations when stability is sufficient while maintaining stability when the margin is small
Solution Approach 2:
The system performs preliminary calculation of the dynamic center of gravity position and tipping line distance before the cylinder reaches the stroke end. Based on this advance assessment, the ECU determines the appropriate velocity profile, allowing the operator to perform impact-based work when conditions are favorable while preventing tipping when conditions are unfavorable
Data Source
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AI summary
Provided is a work machine that, within the limit of not harming dynamic stability, can perform work utilizing the impact generated when a cylinder driving a front work implement collides with a stroke end. A drive control system 34 includes: a stroke end distance calculation and evaluation section 34c that determines whether or not it is possible for cylinders 20A and 21A to collide with a stroke end; a dynamic center of gravity position prediction section 34d that, when the stroke end distance calculation and evaluation section determines that it is possible for the cylinders to collided on the stroke end, predicts a trajectory of the dynamic center of gravity position of a hydraulic excavator 1 from a time when a decelerating operation of the cylinder starts to a time when the cylinder stops; and an allowable velocity changing section 34f that changes the allowable velocity of the cylinder according to a minimum distance from the trajectory of the dynamic center of gravity position predicted by the dynamic center of gravity position prediction section to a tipping line of the hydraulic excavator.