Excavator Bucket Tilt Control Near a Target Design Surface
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Solution Overview
Problem
Existing work machine control systems face instability when attempting to simultaneously perform intervention control and automatic tilt or rotation control, as the speed of the bucket moving away from the target design surface can exceed the limited speed of the boom or arm, leading to unstable control of the work equipment.
Innovation Solution
A control system for a work machine that includes a distance calculation unit, intervention control unit, attachment control unit, and attachment limiting unit to calculate and manage the bucket distance, intervention control amount, and attachment control amount, ensuring the bucket does not intrude on the target design surface and rotates to approach it in a parallel state, while limiting rotation to maintain stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If automatic tilt control is performed to rotate the bucket around the attachment axis such that the edge and target design surface approach each other in parallel state, then the bucket can be positioned parallel to the target design surface, but the bucket distance may be increased causing the bucket to intrude on the target design surface
Solution Approach 1:
The control device calculates the bucket distance between a point on the bucket and the target design surface, and uses this feedback to limit the rotation of the bucket around the attachment axis. When the calculated bucket distance indicates that the bucket is approaching or would intrude on the target design surface, the control device restricts further rotation, thereby preventing intrusion while maintaining the ability to position the bucket parallel to the target surface.
2Manufacturing precision
If intervention control is performed to suppress the speed of work equipment so that the bucket does not intrude on the target design surface, then the bucket intrusion is prevented, but the control amount becomes unstable when the bucket movement speed exceeds the boom or arm lowering speed
Solution Approach 1:
The control device dynamically adjusts the control strategy by switching between intervention control and tilt control based on real-time conditions. When the bucket is approaching the target design surface, intervention control limits the lowering speed of the boom or arm. When the bucket is at a safe distance, tilt control allows the bucket to rotate around the attachment axis to achieve parallel positioning. This dynamic switching maintains control stability while preventing intrusion.
3Manufacturing precision
If both intervention control and automatic tilt control are simultaneously performed, then the bucket can be positioned parallel to the target design surface without intrusion, but the frequent ON/OFF switching of tilt control occurs causing operation instability
Solution Approach 1:
The control device performs preliminary positioning of the bucket by limiting rotation around the attachment axis before intervention control is fully activated. By pre-positioning the bucket at an appropriate distance and orientation, the need for frequent ON/OFF switching of tilt control is reduced, thereby improving operation stability while maintaining positioning precision.
Data Source
AI summary
A distance calculation unit calculates a bucket distance that is a distance between a point on a bucket and a target design surface representing a target shape of an excavation target. An intervention control unit calculates an intervention control amount to suppress a speed of work equipment such that the bucket does not intrude on the target design surface based on the bucket distance. An attachment control unit calculates an attachment control amount to rotate the bucket around an attachment axis such that an edge of the bucket and the target design surface approach each other in a parallel state. An attachment limiting unit limits rotation of the bucket around the attachment axis such that the bucket distance is not increased by a movement of the work equipment based on the intervention control amount and the attachment control amount.