Laser Tracker Calibration Artifact With Kinematic Mount Alignment
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Solution Overview
Problem
Current methods for calibrating laser trackers are time-consuming and prone to inaccuracies due to 'fixturing effects' and thermal expansion uncertainties, making it difficult to achieve precise and repeatable positioning and orientation of measuring points.
Innovation Solution
A calibration and testing system using a spherically mounted retro-reflective laser tracker target coupled with a lightweight, rigid carbon fiber composite beam artifact, supported by a kinematic mount system and orientation mechanism that minimizes elastic deformations and allows for easy alignment and secure holding of the artifact in various orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional artifact calibration methods are used with fixed fixtures, then calibration can be performed, but fixturing effects and thermal expansion uncertainties cause measurement inaccuracies and time-consuming procedures
Solution Approach 1:
The artifact is designed to be dynamically reconfigurable between different orientations (horizontal, vertical, angled) without requiring fixture changes. The kinematic mounts enable quick orientation changes while maintaining precise positioning, eliminating the time-consuming process of reconfiguring fixtures for different calibration positions.
Solution Approach 2:
The invention extracts and eliminates the problematic fixtures from the calibration system. By using a self-contained artifact with integrated kinematic mounts and orientation mechanisms, the system removes external fixturing elements that cause measurement uncertainties and thermal expansion issues.
2Reliability
If measuring points are positioned at various locations and orientations to exercise error sources, then comprehensive calibration is achieved, but positioning repeatability and maintaining accurate reference lengths become difficult
Solution Approach 1:
The artifact incorporates spherical mounting surfaces and retro-reflective targets that provide omnidirectional measurement capability. The spherical geometry ensures that measuring points can be accurately positioned from any orientation while maintaining consistent reference lengths, as spheres have identical properties in all directions.
Solution Approach 2:
The artifact allows changing of orientation parameters (horizontal, vertical, angled positions) while maintaining constant physical dimensions and reference lengths. The kinematic mounts enable parameter changes without affecting the underlying geometric relationships, ensuring positioning repeatability across different orientations.
3Measurement precision
If artifacts are made rigid to maintain reference length, then measurement accuracy improves, but thermal expansion and elastic deformations still affect precision
Solution Approach 1:
The artifact is constructed from carbon fiber composite material that provides high rigidity and dimensional stability while having low thermal expansion characteristics. The composite structure maintains accurate reference lengths under varying thermal conditions and minimizes elastic deformations during handling and positioning.
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 quick and accurate calibration of laser trackers by reducing fixturing effects and thermal uncertainties, improving positioning repeatability and maintaining accurate reference lengths, thus enhancing the precision and efficiency of measurement systems.
Implementation Method 1
a spherically mounted retro-reflective laser tracker target
Data Source
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.