Work Machine Controller Velocity Selection for Surface Contact Prevention
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Solution Overview
Problem
Existing work machine control systems, such as those described in Patent Document 1, fail to prevent the bucket tip end and back surface end from entering the target surface during boom lowering operations, leading to potential surface contact and inefficiencies in excavation and shaping tasks.
Innovation Solution
A work device with a hydraulic cylinder driven by a hydraulic pump, an operation device for instructing hydraulic cylinder operations, and a controller that calculates target velocities for multiple work point candidates based on positional data, posture data, and operation data to control the hydraulic cylinder, ensuring that all work point candidates are least likely to enter the target surface by selecting the appropriate velocity group.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control system uses only boom raising operation to separate the bucket from the target surface, then the bucket can be prevented from entering the target surface in leveling work, but the bucket may still enter the target surface during boom lowering operation
Solution Approach 1:
The control system dynamically adapts to different operation modes (boom raising and boom lowering) by calculating separate target velocities for each mode. The controller determines which operation mode is active and applies the corresponding velocity control strategy, making the system versatile across different working conditions while maintaining reliable prevention of bucket entry into target surface.
Solution Approach 2:
The system changes the control parameter (target velocity) based on the operation mode. For boom raising operation, a first target velocity is calculated, while for boom lowering operation, a second target velocity is calculated. This parameter adaptation allows the same control system to effectively handle different operation scenarios, resolving the contradiction between reliability in one mode and adaptability across modes.
2Device complexity
If the control system calculates target velocity based only on distance from target surface, then the control is simple, but it cannot prevent multiple points on the work device from entering the target surface simultaneously
Solution Approach 1:
The control system segments the work device into multiple monitoring points (first monitoring point and second monitoring point) and calculates separate target velocities for each point based on its specific distance from the target surface. This segmentation allows precise control of each point's position relative to the target surface, preventing multiple points from entering the surface simultaneously while maintaining manageable system complexity through structured calculation procedures.
Data Source
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AI summary
In a work machine including a controller (500) configured to calculate respective target velocities of a hydraulic cylinder (5) for moving a plurality of work point candidates (8a and 8b) set to a work device along an optionally set target surface (60) on the basis of positional data of the target surface, posture data of the work device (15), and operation data of an operation lever (1), and control the velocity of the hydraulic cylinder (5) according to one of a plurality of the calculated target velocities, the controller calculates a candidate point velocity (VTab or VTba) occurring in a case where each of the plurality of work point candidates is moved at the corresponding target velocity (VTa or VTb) and occurring at a remaining work point candidate, selects a velocity at which an entry into the target surface is least likely from among the plurality of candidate point velocities, and controls the hydraulic cylinder according to the target velocity of the work point candidate associated with the selected candidate point velocity.