Excavator Controller Corrects Bucket Tip Position
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Solution Overview
Problem
The accuracy of area limiting control in hydraulic excavators is compromised by the detection accuracy of angle sensors and differences in hydraulic cylinder and flow control valve characteristics, leading to reduced control accuracy of the bucket claw tip, especially due to aged deterioration and individual machine variations.
Innovation Solution
A work machine with a multi-joint work implement and a controller that generates corrective control signals based on topographic information from measurement devices, ensuring the bucket tip moves along a target surface by adjusting the operation of boom, arm, and bucket cylinders, thereby enhancing construction accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If area limiting control is performed based on angle sensor information, then the excavation operation can be assisted to maintain the bucket tip on or above the target surface, but the control accuracy decreases due to insufficient sensor detection accuracy and hydraulic system variations
Solution Approach 1:
The system continuously monitors the actual position of the bucket tip using angle sensors and compares it with the target position. Based on the position deviation, the controller automatically adjusts the hydraulic cylinder operations to correct the bucket tip position, ensuring it remains on or above the target surface. This closed-loop feedback mechanism compensates for sensor inaccuracies and hydraulic variations.
Solution Approach 2:
The controller acts as an intermediary between the angle sensors and the hydraulic control system. It processes the sensor information, calculates the appropriate corrections, and generates control signals for the hydraulic cylinders. This intermediary processing layer enables sophisticated control algorithms that can compensate for system variations and improve overall control accuracy.
2Productivity
If target speeds are converted into pilot pressures using conversion tables, then the control signals for hydraulic cylinders can be generated, but the control accuracy decreases due to differences between conversion table characteristics and actual device characteristics
Solution Approach 1:
The system dynamically adjusts pilot pressures based on real-time feedback from angle sensors rather than relying solely on pre-defined conversion tables. The controller modifies pressure parameters adaptively to match actual hydraulic cylinder and flow control valve characteristics, compensating for deviations between theoretical conversion data and actual device behavior.
Solution Approach 2:
The hydraulic system performs self-adjustment through the feedback control mechanism. When position deviations are detected, the controller automatically generates corrective control signals that adjust pilot pressures to match actual device characteristics, enabling the system to self-correct without external intervention.
3Stability of the object's composition
If the same control as at shipment is applied continuously, then the operation consistency can be maintained, but the control accuracy decreases due to movable part loosening from aged deterioration and individual machine variations
Solution Approach 1:
The control system transitions from a static, fixed control approach to a dynamic, adaptive control approach. The controller continuously adjusts control signals based on real-time feedback from angle sensors, allowing the system to adapt to changes in hydraulic cylinder characteristics, flow control valve variations, and movable part loosening that occur during aging and deterioration.
Solution Approach 2:
The feedback mechanism enables the system to detect position deviations caused by aged deterioration and individual machine variations, and automatically generate corrective control signals. This continuous monitoring and adjustment compensates for the loosening of movable parts and maintains control accuracy despite changes in system characteristics over time.
Data Source
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AI summary
A hydraulic excavator (1) includes a controller (40) for generating, when the tip of a work implement (1A) is approaching a target surface (60) due to the pilot pressure output from an operating device (45a, 45b, 46a), a control signal for a boom cylinder (5) such that the tip of the work implement moves along the target surface and controlling the work implement (1A) by outputting the generated control signal to the flow control valve (15a) of the boom cylinder (5). The controller calculates the positional information of a finished shape (97) formed by the work implement, based on the topographic information input from a topographic measurement device (96) that measures the topography near the work machine and corrects the control signal based on the positional information of the finished shape such that the finished shape gets closer to the target surface.