Construction Machinery Working Point Calculation Using Ground Angle Sensors

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Solution Overview

Problem

Existing construction machine control systems face accuracy issues in calculating the position of the working point due to mechanical backlash and errors caused by tilting of the machine body, which affects the load direction calculation.

Innovation Solution

A construction machine equipped with ground angle sensors and an information processing device that acquires load information and calculates the working point position using signals from these sensors, correcting for mechanical backlash and tilting effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the direction of force of gravity is assumed to be downward with respect to the body for calculating load direction, then the calculation process is simplified, but when the body is tilted, an error occurs in the load direction and thereby the calculation accuracy of the position of the working point declines

Engineering Contradiction:
Improvecalculation process complexityVSAvoidload direction accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces the mechanical assumption-based load direction calculation with an sensor-based detection system. Acceleration sensors detect the actual gravitational force direction in three-dimensional space, and this information is used to correct the load direction calculation, thereby maintaining accuracy even when the body is tilted without significantly increasing system complexity

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the parameter reference frame from body-fixed coordinates to ground-fixed coordinates. By detecting the body's tilt angle using acceleration sensors and transforming the load direction calculation into the ground reference frame, the system maintains accurate load direction calculation regardless of body orientation

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If mechanical backlash is considered in the calculation, then the calculation accuracy of the position of the working point is improved, but the calculation complexity increases due to needing to detect or calculate the direction of eccentricity

Engineering Contradiction:
Improveworking point position accuracyVSAvoidcalculation process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses acceleration sensors to detect the actual gravitational force direction and feeds this information back into the load direction calculation. This feedback mechanism allows the system to automatically compensate for mechanical backlash effects without requiring complex manual calibration or additional mechanical sensors

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent introduces acceleration sensor data as an intermediary element that bridges the gap between the simplified calculation model and the complex real-world conditions. This intermediary information about gravitational force direction enables accurate load direction calculation without directly measuring the complex mechanical backlash effects

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP3543409B1Construction machinery
Publication Date: 2022.08.03 HITACHI CONSTRUCTION MACHINERY CO LTD

AI summary

The construction machine includes: a body (9, 10); work equipment (15) having a plurality of swingable work elements (8, 11, 12); a plurality of hydraulic actuators (5, 6, 7) for driving the work equipment; a plurality of ground angle sensors (13a to 13d) for detecting the ground angles of the work elements; and an excavation support device (400) including an information processing device (100). The information processing device includes: a load information acquiring section (130) for acquiring load information including the load direction in the swing center of at least one of the work elements according to signals from the ground angle sensors; and a working point position calculating section (150) for calculating the position of the working point of the work equipment according to the signals from the ground angle sensors and the load information from the load information acquiring section.