Wire Rope Distance Measurement Using Calibrated Markers

Solution Overview

Problem

Current distance measurement systems for wire ropes, particularly those used in offshore applications, suffer from systematic and cumulative errors, making them inaccurate and unreliable for high-value ropes, which are critical for safe and efficient operation.

Innovation Solution

Implementing a method that uses distance markers, either visual or magnetic, along the wire rope to calibrate incremental rotary encoder measurements, allowing for precise absolute distance calculations by correlating known marker distances with encoder pulses, thereby reducing measurement inaccuracies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If incremental rotary encoder measurements are used for distance measurement along wire ropes, then the measurement system is simple and cost-effective, but systematic and cumulative errors make the measurements inaccurate and unreliable

Engineering Contradiction:

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces distance markers as an intermediary reference system attached to the wire rope. These markers serve as mediators between the rotary encoder and the actual distance being measured, providing known reference points that enable calibration and correction of systematic errors in the encoder measurements without requiring a complete replacement of the measurement system.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the measurement parameters by introducing known reference distances between markers. This allows the system to transform raw encoder pulse counts into calibrated distance measurements by comparing against the known marker spacing, thereby correcting cumulative errors through parameter normalization.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If distance markers are introduced to calibrate measurements, then measurement accuracy improves, but the complexity of the measurement system increases

Engineering Contradiction:

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The distance markers act as intermediaries that bridge the gap between the simple rotary encoder and the requirement for accurate distance measurement. They provide reference points that can be detected by the existing encoder system, enabling calibration without fundamentally changing the measurement apparatus.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent uses multiple distance markers spaced at known intervals along the wire rope. These markers create a replicated pattern of reference points that can be detected sequentially, allowing the system to build up accurate distance measurements through cumulative counting of marker passages rather than requiring a single complex measurement event.

Inventive Principle:

Principle #26Copying

3Reliability

If regular inspections are conducted to monitor wire rope condition, then rope safety and service life are improved, but downtime and operational costs increase

Engineering Contradiction:

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent enables continuous monitoring of wire rope condition by integrating the distance measurement system with regular operational monitoring. The system continuously tracks the position and condition of the rope during normal operations, eliminating the need for separate shutdown inspections while maintaining continuous safety monitoring.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The system provides continuous feedback on wire rope condition through the distance markers and measurement system. This real-time feedback allows operators to monitor rope health during operation and schedule maintenance based on actual condition rather than fixed intervals, reducing unnecessary downtime while maintaining safety.

Inventive Principle:

Principle #23Feedback

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 accurate and reliable distance measurements along the length of wire ropes, enabling better maintenance scheduling, extending the service life of high-value ropes, and ensuring safe operation by identifying wear patterns and damage locations.

Implementation Method 1

counting the rotations of a rotary encoder driven by the moving wire rope

Methodology Applied

Scientific EffectRotational encoding:

Implementation Method 2

detecting a first distance marker crossing the sensor head

Methodology Applied

Scientific EffectMagnetic detection: Magnetic Field

Implementation Method 3

distance markers, either visual or magnetic, along the wire rope

Methodology Applied

Scientific EffectVisual detection:

Data Source

PatentUS9791301B2Method and apparatus for wire rope distance measurement

Publication Date: 2017.10.17

AI summary

Measuring distance along a wire rope, by steps that include moving the wire rope across a sensor head; counting rotations of a rotary encoder driven by the moving wire rope; detecting a first distance marker crossing the sensor head at a first position of the wire rope; detecting a second distance marker crossing the sensor head at a second position of the wire rope; and establishing calibration parameters for producing a calibrated distance measurement corresponding to any output of the rotary encoder, based at least on correlating a known distance between the first and second distance markers to a counted number of pulses of the rotary encoder between the first and second positions of the wire rope.