Autocollimator Position Determination Using Pixel Line Averaging

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Solution Overview

Problem

Existing methods for determining the position of linear objects, such as in autocollimators or conveyor systems, face challenges in achieving high accuracy due to pixel effects caused by detector elements, which lead to systematic deviations in measured light intensity distributions.

Innovation Solution

A method that calculates the orientation angle using the formula α = arctan(ny/dy) / (nx/dx) ± ε, where nx and ny are relatively prime natural numbers, and compensates for pixel effects by averaging positions over multiple pixel lines to determine the center of gravity, thereby reducing measurement uncertainty.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the position of a linear object is determined using a detector element with pixels, then the position can be measured, but pixel effects cause systematic deviations that reduce measurement accuracy

Engineering Contradiction:
Improveposition determination accuracyVSAvoidmeasurement uncertainty
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent divides the object into multiple blocks along its length and determines the center position of each block separately. By segmenting the object into N blocks and analyzing each block's center position independently, the method reduces the influence of pixel effects on the overall measurement, thereby improving position determination accuracy while minimizing measurement uncertainty

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent utilizes the one-dimensional linear structure of the object as a key feature, transforming the two-dimensional pixel grid problem into a one-dimensional position determination problem along the object's length. This dimensional reduction allows for more accurate center position calculation by focusing on the linear coordinate information, effectively compensating for pixel effects

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Measurement precision

If existing devices are modified to improve measurement accuracy, then measurement uncertainty decreases, but device complexity increases

Engineering Contradiction:
Improveposition determination accuracyVSAvoiddevice modification complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent employs self-service by utilizing the object's own linear characteristics and light reflection properties to perform position determination. The method uses the object's inherent geometric features (linear shape, center positions) without requiring additional external reference systems or complex modification to the existing device, thereby improving accuracy while maintaining simple device architecture

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces complex mechanical positioning systems with an optical measurement approach. By using light reflection and detector elements to determine position based on the object's linear features, the method achieves high measurement accuracy without requiring complex mechanical modifications to the device, thus reducing device complexity while improving precision

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

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 allows for accurate determination of object positions with low measurement uncertainty, effectively compensating for pixel effects without additional knowledge and can be retrofitted into existing devices with minimal effort.

Implementation Method 1

a light source (12) for generating a measurement mark (14), which is projected onto a mirror (16)

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

a detector element (18) with detector pixels arranged in Nx rows and Ny columns

Methodology Applied
Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentEP3438604B1Method for determining a position of an at least partially linear object and autocollimator
Publication Date: 2023.07.26 BUNDESREPUBLIK DEUT VERTRETEN DURCH DAS BUNDESMINIST FUR WIRTSCHAFT & ENERGIE DIESES VERTRETEN DURCH DEN PRASIDENTEN DER PHYSIKALISCH TECHNN BUNDESANSTALT
  • EP3438604B1 patent drawingFigure 1~2
  • EP3438604B1 patent drawingFigure 3a~3b
  • EP3438604B1 patent drawingFigure 3c~3d

AI summary

The invention relates to a method for determining the position of an object (26) that is at least partially linear, comprising the step of arranging the object (26) such that a measurement object (24) is imaged on the detector element (18), wherein the detector element (18) has detector pixels (Pi) arranged in Nx rows (Z) and Ny columns (S), the rows (Z) extend in a row direction (Rz), two adjacent rows (Z) have a row spacing (dy), the columns (S) extend in a column direction (Rs) transverse, in particular perpendicular, to the row direction (Rz), two adjacent columns (S) have a column spacing (dx), and there are at least as many columns (S) as rows (Z), and wherein the measurement object (24) extends on the detector element (18) at an orientation angle (α) relative to the row direction (Rz).According to the invention, the orientation angle (α) is given by the formula α=arctannydynxdx±ε, where nx < Nx and ny < Ny are natural, coprime numbers and where ε < 10 arcminutes, and the method comprises the following steps: (i) for each relevant pixel line (S, Z) determining a position (M), in particular a centroid (M), of the object being measured (24), wherein the pixel line is a row or a column, (ii) averaging the positions (M) thus obtained over nPx pixel lines, such that block center positions (L) are obtained, and (iii) determining the position of the object being measured (24) from, in particular all, block center positions (L).