Hydraulic Excavator Frequency-Split Control for Accurate Shaping
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Solution Overview
Problem
Existing work machine control systems face challenges in maintaining stable semiautomatic excavation shaping control, particularly at high excavation speeds, due to the higher inertial load of the boom compared to the arm, leading to potential loss of shaping accuracy.
Innovation Solution
A work machine system that includes a controller capable of calculating and separating target speeds into low and high frequency components, allocating high frequency components to the front member with a smaller inertial load, such as the bucket, to achieve precise control and maintain the bucket above the target surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the arm performs crowding action at high excavation speed, then productivity is improved, but the bucket distal end may move over a long distance below the target surface resulting in loss of shaping accuracy
Solution Approach 1:
The control system dynamically adjusts the boom raising speed based on real-time conditions. When the bucket distal end enters below the target surface, the boom raising speed is increased to bring it back. This dynamic speed adjustment allows high excavation speeds while maintaining shaping accuracy, resolving the contradiction between productivity and precision.
Solution Approach 2:
The system continuously monitors the position of the bucket distal end relative to the target surface and adjusts the boom raising speed accordingly. This feedback mechanism ensures that even at high excavation speeds, any deviation below the target surface is quickly corrected, maintaining shaping accuracy while enabling high productivity.
2Manufacturing precision
If the boom raising speed is suppressed when the bucket distal end reaches the target surface, then shaping accuracy is maintained, but the bucket distal end may lift up from the target surface resulting in loss of control stability
Solution Approach 1:
The boom raising speed is dynamically adjusted based on the bucket distal end position. When the bucket reaches the target surface, the speed is suppressed to prevent overshooting and maintain shaping accuracy. This dynamic adjustment resolves the contradiction by enabling precise control while maintaining stability through continuous adaptation to position feedback.
Solution Approach 2:
The control system anticipates potential lifting of the bucket distal end from the target surface and adjusts the boom raising speed in advance. By suppressing the speed just before the bucket reaches the target surface, the system prevents both overshooting and subsequent lifting, maintaining both shaping accuracy and control stability.
3Manufacturing precision
If the boom raises at high speed to correct bucket position, then shaping accuracy is recovered, but the inertial load of the boom causes delay in actual speed change
Solution Approach 1:
The control system issues speed change commands to the boom in advance, anticipating the need for correction. By preparing the boom for speed changes before they are critically needed, the system compensates for the inertial delay, enabling faster response while maintaining shaping accuracy.
Solution Approach 2:
The system continuously monitors the actual boom speed and position, comparing it with the desired trajectory. This feedback allows the controller to adjust commands in real-time, compensating for the delay caused by boom inertia and maintaining shaping accuracy despite the inherent response time lag.
Data Source
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.