Excavator Grade Assist for Stick-Boom Delay Synchronization
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Solution Overview
Problem
Construction machines, such as excavators, often dig below a desired grade due to unsynchronized movement of their parts, particularly because of delays in the hydraulic system, leading to unintended excavation below the specified grade.
Innovation Solution
A method and apparatus that delay and synchronize the movement of the stick and boom of an excavator using a processor-controlled system, sensing user inputs and actuating hydraulic valves to maintain the bucket above the desired grade by predicting the movement of the stick and boom based on sensors and a desired surface trajectory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the stick is actuated quickly in response to user input, then the responsiveness and productivity of the excavator is improved, but the bucket may dig below the desired grade due to hydraulic delay before the boom can move upward to prevent it
Solution Approach 1:
The system performs preliminary action by predicting the future position of the bucket based on current stick actuation commands and hydraulic delay characteristics. Before the actual digging occurs, the control system calculates the anticipated grade violation and preemptively adjusts the boom position or limits stick movement to prevent the bucket from going below the desired grade.
Solution Approach 2:
The system employs feedback by continuously monitoring the actual position of the boom, stick, and bucket using sensors, comparing it with the desired trajectory, and adjusting the hydraulic actuation in real-time. This closed-loop control ensures that even with hydraulic delays, the bucket remains at or above the desired grade while maintaining responsive operation.
2Speed
If the hydraulic system is designed for high speed response, then the productivity is improved, but the synchronization between boom and stick movement deteriorates, causing the bucket to dig below grade
Solution Approach 1:
The control system acts as an intermediary between the user's commands and the hydraulic actuators. It receives the desired movement commands, predicts the actual movement considering hydraulic delays, and generates corrected control signals that compensate for the timing mismatches. This intermediary layer ensures synchronized movement of the boom and stick despite the high-speed hydraulic system's inherent delays.
Solution Approach 2:
The system dynamically adjusts the control parameters based on real-time conditions. The predicted delay values are continuously updated based on the current hydraulic system state, and the control algorithm adapts the boom and stick movement profiles to maintain synchronization. This dynamic adjustment allows the system to maintain precise coordination even as operating conditions change.
3Manufacturing precision
If the stick movement is delayed to synchronize with boom movement, then the grade control accuracy is improved, but the operational time and productivity are reduced
Solution Approach 1:
Rather than delaying stick movement, the system performs preliminary action by predicting the bucket's future position and preemptively adjusting the boom position or limiting stick movement. This approach maintains the responsiveness of the stick while preventing grade violations, avoiding the time loss associated with actual delays.
Solution Approach 2:
The real-time feedback system continuously monitors the actual positions of all components and compares them with the desired trajectory. By providing immediate feedback and making instantaneous corrections, the system achieves precise grade control without introducing artificial delays, thereby maintaining high productivity while ensuring accuracy.
Data Source
AI summary
A method for machine grade assist includes determining whether user input will cause an implement of a machine to dig below a desired grade. User input to move a stick of an excavator can be blocked and/or delayed using hydraulic pressure so that movement of both the stick and the boom of the excavator can be synchronized to prevent a bucket of the excavator from digging below a desired grade when the stick is moved.