Excavator Front-Member Speed Allocation for Accurate Shaping
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Solution Overview
Problem
Existing work machine control systems face challenges in maintaining accurate semiautomatic excavation shaping control, especially at high excavation speeds, due to the higher inertial load of the boom and delays in speed changes, leading to potential loss of shaping accuracy.
Innovation Solution
A work machine system with a controller that separates target speed signals into low and high frequency components, allocating high frequency components to the front member with a smaller inertial load to calculate and control target speeds, ensuring stable positioning above a target surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the arm action is performed at a high excavation speed, then the productivity is improved, but the shaping accuracy deteriorates due to the higher inertial load of the boom and delay in speed change
Solution Approach 1:
The control system segments the speed control into two independent parts: a speed command value (Vcmd) that determines the overall excavation speed, and a correction value (Vcorr) that adjusts for inertial delays. This segmentation allows the system to maintain high excavation speeds while compensating for the boom's inertial load through the separate correction mechanism, thereby preserving shaping accuracy even at high productivity levels
Solution Approach 2:
The control system implements feedback by calculating a correction value based on the difference between the actual bucket tip speed and the commanded speed. This feedback loop continuously monitors the boom's inertial effects and adjusts the correction value accordingly, enabling the system to maintain accurate shaping control while operating at high excavation speeds. The feedback mechanism directly addresses the delay in speed change caused by the boom's inertial load
2Measurement precision
If the boom raising speed increases to prevent bucket tip from entering target surface, then the positioning accuracy is improved, but the response time deteriorates due to inertial load
Solution Approach 1:
The control system performs preliminary action by calculating and applying a correction value in advance to compensate for the boom's inertial load. Instead of waiting for positioning errors to occur and then reacting, the system proactively adjusts the boom speed command based on predicted inertial effects, thereby maintaining positioning accuracy without the time delay associated with reactive corrections
Solution Approach 2:
The feedback mechanism continuously monitors the actual bucket tip position and speed, and adjusts the correction value to compensate for inertial delays. This real-time feedback allows the system to maintain accurate positioning control while minimizing response time, as the correction is continuously updated based on actual system behavior rather than waiting for errors to manifest
Data Source
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AI summary
A controller (25) of the hydraulic excavator (1) includes a signal separation section (150) that separates each of target speed signals for a plurality of front members (8, 9, 10) into a low frequency component and a high frequency component, a high fluctuation target speed calculation section (143) that allocates the separated high frequency components preferentially to a front member having a relatively small inertial load to calculate high fluctuation target speeds individually for the plurality of front members, a high fluctuation target actuator speed calculation section (141c) that calculates high fluctuation target speeds individually for the plurality of actuators from the high fluctuation target speeds for the plurality of front members, a low fluctuation target actuator speed calculation section (141b) that calculates low fluctuation target speeds individually for the plurality of actuators from the low frequency components separated by the signal separation section, and an actuator controller (200) that controls the plurality of actuators individually based on values obtained by adding the high fluctuation target speeds and the low fluctuation target speeds.