Reaction-Force Control for Construction Machine Trajectory Precision

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Solution Overview

Problem

Construction machinery, such as hydraulic excavators, face challenges in high-precision and high-speed operation due to the need for skilled operator manipulation of multiple front members, leading to operator fatigue and reduced work efficiency, especially when following linear target trajectories during tasks like excavation.

Innovation Solution

A construction machine equipped with a front working device comprising multiple actuators and an operating unit, featuring a reaction-force applying device and a control system that detects actual operator input, sets target trajectories and speeds, and adjusts operation reaction forces based on differences between target and actual inputs to guide the operator in maintaining precise trajectory adherence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If multiple front members are operated in combination to follow a linear target trajectory, then work precision is improved, but operator skill requirement and manipulation complexity increase

Engineering Contradiction:
Improvetrajectory following precisionVSAvoidmanipulation complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system detects the actual position of the bucket tip relative to the target trajectory and computes the distance to the boundary. This feedback information is used to generate operation reaction forces that guide the operator back toward the target trajectory, enabling precision work without requiring complex manual coordination of multiple front members

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The reaction-force applying means acts as an intermediary between the control system and the operating members. It translates trajectory deviation information into intuitive force feedback on the operating levers, mediating the complex multi-member coordination task into a simpler single-lever operation with force guidance

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If operation reaction force is applied to assist operators, then ease of operation is improved, but the system complexity increases

Engineering Contradiction:
Improveoperator assistanceVSAvoidcontrol system complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The control device performs multiple functions: it detects operator input, computes front working device attitude, calculates distance to trajectory boundary, determines target reaction forces, and applies correction forces. By consolidating these functions into a single multi-functional control system, the patent achieves operator assistance without proportionally increasing overall system complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Manufacturing precision

If high-precision work is performed along target trajectory, then work quality is improved, but work speed decreases due to operator fatigue

Engineering Contradiction:
Improvework precisionVSAvoidwork efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The system provides self-correction capabilities through automatic computation of trajectory deviation and generation of correction forces. The reaction-force applying means continuously adjusts to keep the bucket tip on the target trajectory, allowing the system to maintain precision automatically without requiring constant operator attention and correction, thereby reducing fatigue and maintaining high work speed

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3348715B1Construction machine
Publication Date: 2020.05.06 HITACHI CONSTRUCTION MACHINERY CO LTD
  • EP3348715B1 patent drawingFigure 1
  • EP3348715B1 patent drawingFigure 2
  • EP3348715B1 patent drawingFigure 3

AI summary

A construction machine includes a control device having a reaction-force correction control section. When a difference between a target operator input and an actual operator input for a front member exceeds a preset range, the reaction-force correction control section executes correction to increase an operation reaction force to be applied by a reaction-force applying device to an operating unit operating an actuator driving the front member. When the difference falls within the range, the reaction-force correction control section executes correction to decrease the operation reaction force to be applied by the reaction-force applying device to the operating unit operating the actuator driving the front member.