Laser Tracker Retroreflector Orientation Measurement
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Solution Overview
Problem
Current laser-tracker based six degrees of freedom (6 DOF) measuring systems are complicated, expensive, and often inconvenient for users, with limitations in accuracy and depth of field, particularly in handheld applications.
Innovation Solution
A laser tracker system that includes a tracking unit with a payload assembly emitting a first laser beam and a pattern projector assembly emitting a second laser beam shaped into a two-dimensional pattern, combined with a retroreflector and a position sensor assembly where the center of symmetry of the retroreflector is on a different plane than the position sensor assembly, allowing for the measurement of orientation by illuminating the target with a two-dimensional pattern and calculating the orientation from recorded signature values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional laser tracker systems with multiple sensors and complex optics are used to measure six degrees of freedom, then measurement capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple measurement functions into a single integrated target assembly. The retroreflector and position sensor assembly are merged into one compact unit, allowing the laser tracker to measure both position and orientation (six degrees of freedom) using a single target rather than requiring separate sensors for each measurement type.
Solution Approach 2:
The target assembly serves multiple functions simultaneously: the retroreflector returns the laser beam for position measurement, while the position sensor assembly detects the angle of incidence for orientation measurement. This multi-functional design eliminates the need for separate measurement devices for each degree of freedom.
2Measurement precision
If traditional laser tracker systems with multiple sensors are used to measure six degrees of freedom, then measurement capability is improved, but manufacturing cost increases
Solution Approach 1:
The patent combines multiple measurement functions into a single integrated target assembly. The retroreflector and position sensor assembly are merged into one compact unit, allowing the laser tracker to measure both position and orientation (six degrees of freedom) using a single target rather than requiring separate sensors for each measurement type.
3Ease of operation
If handheld laser tracker applications are used, then mobility and convenience are improved, but measurement accuracy deteriorates due to vibrations and movement
Solution Approach 1:
Instead of trying to stabilize the laser tracker during handheld operation, the patent inverts the approach by making the target (attached to the object being measured) the stable reference. The retroreflector and position sensor assembly move together as a rigid unit with the object, eliminating relative motion errors between measurement components.
Solution Approach 2:
The position sensor assembly provides real-time feedback on the angle of incidence of the laser beam. This feedback allows the system to calculate and compensate for orientation changes, maintaining measurement accuracy even during handheld operation when vibrations and movements occur.
4Measurement precision
If beam splitters and polarizing optics are used to measure orientation angles, then measurement capability is improved, but device complexity and alignment requirements increase
Solution Approach 1:
The patent extracts the orientation measurement function from complex beam splitter and polarizing optics systems and implements it directly in the target assembly using the position sensor assembly. This eliminates the need for complex optical path manipulation while achieving the same orientation measurement capability.
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 provides a simple, inexpensive, and accurate method for measuring six degrees of freedom, improving user convenience and reducing errors, while maintaining high accuracy even in handheld applications.
Implementation Method 1
The target may include a retroreflector and a position sensor assembly provided proximate to the retroreflector
Implementation Method 2
The position sensor assembly may include first and second linear arrays orthogonal to one another
Data Source
AI summary
A laser tracker system for measuring six degrees of freedom may include a main optics assembly structured to emit a first laser beam, a pattern projector assembly structured to emit a second laser beam shaped into a two-dimensional pattern, and a target. The target may include a retroreflector and a position sensor assembly. A center of symmetry of the retroreflector may be provided on a different plane than a plane of the position sensor assembly. A method of measuring orientation of a target may include illuminating the target with a laser beam comprising a two-dimensional pattern, recording a position of the two-dimensional pattern on a position sensor assembly to create a measured signature value of the two-dimensional pattern, and calculating an orientation of the target based on the measured signature value.