Calibration Device for Circular Object Center Determination

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current methods for determining the center of circular objects in computer-assisted surgery procedures are inefficient due to the need for large reference blocks and time-consuming digitization, leading to handling errors and inaccuracies.

Innovation Solution

A calibration device with a tracking member and object contacting portions is used to determine spatial coordinates of two points on a circular object's edge, allowing a computer tracking system to calculate the center point using geometric parameters, eliminating the need for extensive digitization and large reference blocks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a digitizing CAS pointer is used to determine individual points on the cup's circumference, then the center can be calculated, but the procedure becomes time-consuming and introduces handling errors

Engineering Contradiction:

Improvecenter determination accuracyVSAvoiddigitization time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the mechanical digitizing pointer system with a vision-based optical system. The camera captures an image of the cup's circumference, and image processing algorithms automatically identify points on the circumference and calculate the center, eliminating the need for manual mechanical digitization and significantly reducing time while maintaining or improving accuracy

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates a digital copy (image) of the cup's circumference rather than physically touching and measuring it point-by-point. This optical copy allows for rapid automated analysis of multiple points simultaneously, eliminating the sequential manual measurement process and reducing both time and handling errors

Inventive Principle:

Principle #26Copying

2Stability of the object's composition

If a large reference block is used to immobilize the cup, then the cup can be stabilized, but the device complexity and space requirements increase

Engineering Contradiction:

Improvecup immobilization stabilityVSAvoidreference block size

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent extracts the essential function of immobilization from the large reference block and implements it through a minimal set of contact points (jaws or clamps) that hold the cup steady. This eliminates the need for a bulky reference block while maintaining sufficient stability for accurate measurement

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies immobilization only at the specific locations where the cup needs to be held steady, rather than using a large block that constrains the entire cup. The contact points are positioned strategically to provide adequate stabilization with minimal device complexity

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS7302355B2Method and apparatus for calibrating circular objects using a computer tracking system

Publication Date: 2007.11.27 ORTHOSOFT ULC

AI summary

A method of calibrating a circular portion of an object, such as to determine the center point of the object, is provided. The method includes determining spatial coordinates of at least two points on a circumferential edge of the circular portion of the object, and calculating the center point of the circular portion using the spatial coordinates of the two points and a geometric parameter representative of the diameter of the circular portion. A calibration device and system are also provided for use with a computer tracking system in order to calibrate such an object having a circular portion.