Laser Tracker Calibration Fixture for Fast, Low-Stress Alignment
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Solution Overview
Problem
Calibrating laser trackers is challenging due to the difficulty in precisely and accurately positioning and orienting reference artifacts, which introduces uncertainty from factors like fixturing effects, thermal expansion, and the time-consuming nature of the process, affecting the accuracy of length measurement system tests.
Innovation Solution
A modular calibration system using a spherically mounted retro-reflective laser tracker target coupled to an artifact made of low thermal expansion material, supported by a kinematic mount system and orientation restraint mechanism, allowing for quick and precise positioning and orientation, and facilitating easy alignment with the laser tracker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional artifacts are used for calibration, then measurement accuracy can be maintained, but the positioning and orienting process becomes time-consuming and introduces fixturing effects
Solution Approach 1:
The artifact incorporates a movable mounting mechanism that allows dynamic repositioning of the artifact along the laser tracker's field of view. The mounting system includes adjustable clamps and positioning features that enable rapid reconfiguration without requiring precise manual alignment, thus reducing positioning time while maintaining calibration accuracy
Solution Approach 2:
The artifact includes self-aligning features such as built-in alignment marks and automated positioning mechanisms that reduce the need for operator intervention. The system enables operators to quickly set up the artifact without requiring extensive skill or time for manual positioning and orienting
2Stability of the object's composition
If traditional fixturing methods are used to position artifacts, then stable positioning can be achieved, but fixturing effects introduce uncertainty to the reference length
Solution Approach 1:
The patent removes traditional fixturing elements from the calibration setup. The artifact is designed to be positioned and secured without clamps, vises, or other fixturing devices that could introduce stress or deformation. The mounting system uses minimal-contact methods to hold the artifact, eliminating fixturing effects that would otherwise contaminate the reference length measurement
Solution Approach 2:
The artifact incorporates materials and design features that compensate for environmental variations. By changing physical parameters such as using low thermal expansion materials and designing compensation mechanisms, the system maintains reference length accuracy despite temperature fluctuations or minor positioning variations, without requiring rigid fixturing
3Temperature
If artifacts are made from materials with low thermal expansion, then thermal stability is improved, but manufacturing complexity increases
Solution Approach 1:
The artifact is constructed from composite materials that combine low thermal expansion properties with manufacturability. The design uses available materials and manufacturing techniques to achieve thermal stability without requiring exotic or difficult-to-process materials, balancing performance requirements with practical manufacturing considerations
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
The system enables rapid and accurate calibration of laser trackers by minimizing deformations and fixturing effects, ensuring reliable reference length determination and reducing wear on the tracker, while being portable and easy to use.
Implementation Method 1
a spherically mounted retro-reflective laser tracker target
Data Source
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AI summary
A system and method of calibrating a laser tracker is provided. The system includes a support system for quickly and easily moving an artifact to a desired position and orientation and for holding the artifact in the position and orientation. An adjustable alignment mirror is coupled to a first end of the artifact so that the more accurate ranging system of the laser tracker can be isolated to determine a reference length of the artifact. Additional measurements are then taken to exercise one or more error source within the tracker. The support system includes a positioner and a support beam for positioning and supporting the artifact. The artifact is coupled to the support beam using kinematic clamps that are designed to reduce or eliminate errors associated with over-constraining the artifact. The artifact is movable between a deployed configuration for use and a stowable configuration for ease of storage and transportation.