Virtual Surface Offset for Spherical Tip Positioning

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Solution Overview

Problem

Position detection systems with spherical scanning tips face challenges in accurately determining the point of contact on a surface, leading to positional errors due to the angle of the instrument, especially when the scanning tip has a large radius, which can result in errors of a few millimeters and is not easily correctable.

Innovation Solution

The method involves creating a virtual model surface at a distance corresponding to the radius of the spherical scanning tip's center, allowing position values to be assigned independently of the angle, using the sphere center as the position reference point, and applying a transformation rule to maintain relative position accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a spherical scanning tip with large radius is used, then the instrument can be guided more easily and gently over soft surfaces, but the positional error increases due to the angle of contact

Engineering Contradiction:
Improveease of guiding scanning instrumentVSAvoidposition detection accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent introduces a virtual surface as an intermediary between the spherical scanning tip and the actual model surface. This virtual surface is calculated at a distance from the model surface equal to the radius of the spherical tip, allowing the system to track the center of the sphere rather than the contact point. This mediator enables accurate position detection regardless of the scanning angle while maintaining the ease of use provided by the large spherical tip.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the scanning tip has a large spherical radius, then navigation over soft surfaces is facilitated, but the point of contact on the surface cannot be determined precisely

Engineering Contradiction:
Improveadaptability to soft surfacesVSAvoidcontact point determination accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent transitions from tracking position in two dimensions (the model surface) to three dimensions by introducing a virtual surface offset by the spherical tip radius. This dimensional shift allows the system to reference the center of the spherical tip, eliminating the ambiguity of contact point determination while preserving the adaptability benefits of the large spherical scanning tip.

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

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 enables accurate position detection and minimizes positional errors even with scanning instruments having large spherical radii, facilitating smooth navigation over soft surfaces like the human face, while avoiding errors associated with the angle of contact.

Implementation Method 1

The alternating electromagnetic field of the generator induces currents in the coils, which depend on the orientation of each coil relative to the electromagnetic field.

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2779932B1Registering method, position detecting system, and scanning instrument
Publication Date: 2019.08.21 FIAGON AG MEDICAL TECH
  • EP2779932B1 patent drawingFigure 1
  • EP2779932B1 patent drawingFigure 2

AI summary

The invention relates to a method for assigning position values detected by means of a position detecting system to a topographic image of an object or body part, said method having the following steps: - providing a topographic model of an object or body part, - scanning a surface of the object or body part, - detecting position values during the scan, and - assigning detected position values to corresponding positions in the topographic model, wherein the detected position values are assigned to points of a virtual surface of the topographic model, said virtual surface being spaced from a model surface by a distance that corresponds to a radius of a partially spherical scanning tip of a scanning instrument with which each surface of the object or body part is scanned.