AACMM Optical Localization for Accurate Repositioned Measurement

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Solution Overview

Problem

Portable articulated arm coordinate measuring machines (AACMMs) face challenges with probe accuracy when changed, subjected to shocks, and difficulties in use with other 3D measuring devices, requiring improvements for accurate localization and coordinate measurement across different positions and frames of reference.

Innovation Solution

A portable AACMM system that includes a base with a manually positionable arm portion and image capture devices for localizing the machine by capturing images of positioning elements, determining 3D coordinates, and computing translation matrices to maintain consistent coordinate frames across different positions, ensuring accurate measurement and minimization of mechanical shock.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If AACMM probes or accessories are changed, then versatility is improved, but measurement precision deteriorates due to drift

Engineering Contradiction:

Improveprobe interchangeabilityVSAvoidmeasurement accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The system performs preliminary localization by capturing images of positioning elements and computing translation matrices before measurement operations begin. This preliminary action establishes a reference coordinate system that remains consistent across probe changes, eliminating drift issues when accessories are swapped.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary coordinate transformation system using image capture devices and translation matrices. This intermediary layer decouples the measurement data from the physical probe position, allowing probe interchangeability while maintaining measurement consistency through mathematical coordinate transformations.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If AACMM is moved from place to place, then adaptability is improved, but measurement precision deteriorates due to loss of accuracy

Engineering Contradiction:

Improvemobile positioning capabilityVSAvoidmeasurement accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent replaces mechanical alignment and positioning systems with an optical/image-based localization system. Instead of relying on mechanical references that lose accuracy when moved, the system uses image capture devices to detect positioning elements and compute translation matrices, enabling accurate relocation without mechanical drift.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If localization system is implemented, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improvecoordinate measurement accuracyVSAvoidsystem complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The image capture devices serve multiple functions: they localize the AACMM base, detect positioning elements, and provide reference data for coordinate transformations. This multi-functionality reduces the need for separate localization hardware, offsetting the complexity increase with operational versatility.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Enables the AACMM to maintain accurate 3D coordinate measurements across different positions and frames of reference, reducing the need for recalibration and improving usability with other 3D measuring devices by using image capture devices for localization and translation matrix calculations.

Implementation Method 1

capturing a first set of images of a positioning element in the predetermined area using at least two image capture devices. The localization further includes determining first 3D coordinates of the positioning element in the first frame of reference from the first position using the first set of images

Methodology Applied

Scientific EffectPhotogrammetry: Photogrammetry

Data Source

PatentUS11454492B2Articulated arm localization

Publication Date: 2022.09.27 FARO TECHNOLOGIES INC

AI summary

Techniques for localizing a portable articulated arm coordinate measuring machine (AACMM) are described. An example localization method includes in response to an AACMM base being placed at a first position, capturing a first set of images of a positioning element in a predetermined area. The method further includes determining first 3D coordinates of the positioning element using the first set of images. 3D coordinates corresponding to a position of a first measurement probe in the predetermined area are computed using the first 3D coordinates. Further, the method includes, in response to the base being moved to a second position, determining second 3D coordinates of the positioning element from the second position using a second set of images. Further, the localization method includes determining a translation matrix to convert the second 3D coordinates to the first 3D coordinates.