Detector Arrangement for Mobile Work Machine Positioning

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Solution Overview

Problem

Conventional methods for determining the position and state of motion in mobile work machines, such as forest work units, face challenges due to mechanical impacts, vibrations, and environmental conditions, leading to measurement distortions and errors, particularly with sensors used in inclination and angular velocity detection.

Innovation Solution

A detector arrangement that uses multiple sensors, including acceleration, angular velocity, and angular acceleration sensors, along with a data processing unit to determine structural-part-specific position and state of motion information, correcting measurement errors by combining signals from different variables and referencing them against a predetermined angle, such as the gravity vector or magnetic field.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If acceleration sensors are used for inclination detection, then angular position information can be obtained, but measurement accuracy deteriorates due to distortion from other accelerations (vibrations, mechanical impacts)

Engineering Contradiction:
Improveangular position measurement accuracyVSAvoiddistortion from other accelerations
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The system uses feedback by continuously monitoring multiple measured variables (acceleration, angular velocity, angular acceleration) and using the data processing means to determine structural-part-specific position information that compensates for measurement errors. The system feeds back correction information to improve the accuracy of angular position determination despite the presence of harmful accelerations.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The invention changes the parameters being measured by using multiple different measured variables (acceleration, angular velocity, angular acceleration) instead of relying on a single parameter. This multi-parameter approach allows the data processing means to distinguish between gravitational acceleration and other harmful accelerations, thereby improving measurement accuracy.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If signal filtering is applied to reduce distortion from other accelerations, then measurement accuracy improves, but response speed deteriorates

Engineering Contradiction:
Improveangular position measurement accuracyVSAvoidresponse speed to angle changes
Core Design Contradiction:
Measurement precisionVSSpeed

Solution Approach 1:

Instead of filtering the acceleration signal, the system changes approach by measuring multiple parameters simultaneously (acceleration, angular velocity, angular acceleration) and using data processing to determine position information. This avoids the need for heavy filtering while still achieving accurate measurements with fast response.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system uses feedback mechanisms where the data processing means continuously processes multiple measured variables to determine corrected position information, providing accurate and responsive angular position data without the lag introduced by filtering.

Inventive Principle:
Principle #23Feedback

3Measurement precision

If gyroscope measuring devices are used for angular velocity detection, then angular velocity measurement is obtained, but measurement accuracy deteriorates due to error accumulation over time

Engineering Contradiction:
Improveangular velocity measurement capabilityVSAvoidangular position determination accuracy over time
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The invention merges multiple measurement approaches by combining gyroscope-based angular velocity detection with acceleration sensor data and angular acceleration measurements. The data processing means integrates these multiple sources to determine structural-part-specific position information, preventing error accumulation by continuously referencing multiple independent measurement streams.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The system employs feedback by using the data processing means to continuously determine corrected position information based on multiple measured variables, compensating for gyroscope drift and error accumulation over time through continuous reference to other measurement sources.

Inventive Principle:
Principle #23Feedback

4Measurement precision

If sensors are placed in connection with machine structures for position determination, then position measurement is enabled, but sensor durability deteriorates due to mechanical impacts, vibrations, and environmental conditions

Engineering Contradiction:
Improveposition and state of motion determinationVSAvoidsensor durability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The invention merges multiple sensor types (acceleration sensors, angular velocity sensors, angular acceleration sensors) distributed across different structural parts. This distributed arrangement reduces the burden on any single sensor and allows the system to maintain measurement capability even if individual sensors are exposed to harsh conditions.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The system applies local quality by placing different types of sensors at different locations on the machine structure, each optimized for its specific position. This allows sensors to be positioned where they can measure required parameters while minimizing exposure to the most severe mechanical impacts and environmental conditions.

Inventive Principle:
Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach provides more accurate, reliable, and swift determination of mutual position and state of motion, reducing errors caused by disturbances and environmental factors, while allowing flexible placement of sensors and avoiding mechanical stress, thus enhancing the durability and service life of the detection system.

Implementation Method 1

A problem with detectors based on an acceleration sensor is that other accelerations, in addition to gravitational acceleration, directed at the sensor cause distortion in an angular value

Methodology Applied
Scientific EffectGravitation: Gravitation

Implementation Method 2

Detectors based on detecting angular velocity, such as gyroscope measuring devices, in turn, detect the rate of change in the angle rather than the absolute position in relation to the direction of an acceleration due to gravity vector, for instance

Methodology Applied
Scientific EffectGyroscope effect: Gyroscope

Data Source

PatentEP2890956B1Detector arrangement in connection with a mobile work machine
Publication Date: 2020.07.08 PONSSE OY
  • EP2890956B1 patent drawingFigure 1a~1b
  • EP2890956B1 patent drawingFigure 2a~3
  • EP2890956B1 patent drawingFigure 4

AI summary

The invention relates to a detector arrangement and method for determining a mutual position or a mutual state of motion of at least two structural parts of a mobile work machine. The arrangement comprises detectors configurable to determine at least in one direction of measurement at least two different measured variables in order to determine at least structural-part-specific position or state of motion information for each direction of measurement. The arrangement further comprises a data processing means for receiving measurement signals describing measured variables as well as for determining a mutual position or state of motion of the structural parts on the basis of the structural-part-specific position or state of motion information.