Optical Coherence Tomography Reference Arm Tracking Error Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing measuring methods for surface topology using optical coherence tomography face tracking errors due to delayed responses from robotic axes and reciprocating movements, which affect the accuracy of weld and cut quality analysis.
Innovation Solution
A method and device that guide the reference arm of an optical coherence tomograph along a surface topology using a manipulator and deflection unit, compensating for tracking errors by establishing a planning path length and normalizing measured distances to a standard distance, allowing for error-free inference of surface topology without altering the measuring device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a robot manipulator is used to guide the measuring region along the intended track, then automation and productivity are improved, but tracking errors occur due to delayed response of the axes, worsening measurement precision
Solution Approach 1:
The system continuously measures the actual distance between the zero point and the workpiece surface at multiple measuring points along the track, compares it with the planning path length, and uses this feedback to normalize the measured distances. This closed-loop approach compensates for tracking errors caused by manipulator inertia and delayed axis response.
Solution Approach 2:
The system changes the parameter representation by normalizing actual distances to a standard distance based on the planning path length. This transformation converts absolute distance measurements into relative position data that is independent of tracking errors, allowing accurate surface topology analysis despite manipulator delays.
2Loss of time
If the manipulator moves quickly to improve productivity, then measurement time is reduced, but mechanical inertia causes lag errors where planned measuring points precede actual measuring points, worsening measurement precision
Solution Approach 1:
The system converts the harmful effect of mechanical inertia and tracking delays into a beneficial normalization process. By measuring actual distances and comparing them with planning path lengths, the system identifies and compensates for lag errors, transforming the problem of speed-induced inaccuracies into a solvable calibration task.
Solution Approach 2:
The system performs preliminary measurements of actual distances at multiple measuring points before final surface topology analysis. These preliminary data points are used to establish the planning path length and create normalization factors that correct for inertial effects during subsequent measurements.
3Measurement precision
If multiple measurements are carried out point-by-point to improve measurement precision, then accurate surface topology data is obtained, but measurement time increases, worsening productivity
Solution Approach 1:
The system replaces purely mechanical point-by-point scanning with an optical measurement approach using optical coherence tomography. The measuring device captures distance information optically at multiple points simultaneously or in rapid succession, reducing the time penalty associated with detailed multi-point measurements while maintaining high precision through the normalization process.
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 significantly reduces measurement errors by normalizing actual distances to a standard distance, ensuring accurate surface topology analysis and quality assurance, even in the presence of mechanical inertia and reciprocating movements.
Implementation Method 1
an optical coherence tomograph for measuring an actual distance between a zero point of a measuring region of the optical coherence tomograph and a workpiece surface
Data Source
AI summary
A measuring device and measuring method for capturing a surface topology of a workpiece uses an optical coherence tomograph having a reference arm guided by a manipulator or a deflection unit to position a measuring region of the scanner. The reference arm is guided along an actual track, which at least partially deviates from an intended track due to disturbing influences like lag errors of the manipulator. An actual distance (dm) between a zero point of the measuring region and a workpiece surface is measured at at least one measuring point of the actual track. A planning path length (Ip) of the reference arm is established for the at least one measuring point for the compensation of the disturbing influences, and the measured actual distance (dm) is normalized to a standard distance (dn) with the aid of the planning path length (Ip).