3D Projector Pose Calibration for CAD-Aligned Building Layout
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Solution Overview
Problem
Existing 3D projectors lack the capability to rapidly and accurately position building elements according to building plans in construction and manufacturing applications, requiring improved precision and adaptability for architectural and engineering tasks.
Innovation Solution
A 3D projector system with a projecting mechanism and gimbal mechanism, capable of determining a six degree-of-freedom pose to align with anchor targets in a CAD model, using galvanometer mirrors and a rangefinder to project a glowing template pattern onto an as-built surface, adjusting for angular errors and surface coordinates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional surveying tools (total stations, tape measures) are used to position building elements, then workers can make marks based on measurements, but the process is time-consuming and lacks rapid positioning capability
Solution Approach 1:
The patent uses a 3D projector to create a glowing template pattern that copies the desired building element positions directly onto the work surface. Instead of manually measuring and marking each point, the system projects a visual template showing all required positions simultaneously, enabling workers to rapidly transfer the pattern to the actual building elements without time-consuming individual measurements
Solution Approach 2:
The patent replaces traditional mechanical surveying tools (total stations, tape measures, chalk lines) with an optical projection system. The 3D projector uses galvanometer mirrors to steer a laser beam and create glowing template patterns, substituting mechanical measurement and marking processes with optical visualization that provides rapid positioning feedback
2Manufacturing precision
If manual measurement tools (tape measures, levels) are used to mark positions, then workers can make marks on building elements, but the positioning accuracy is limited by human measurement precision
Solution Approach 1:
The system projects a glowing template pattern that precisely copies the CAD model coordinates onto the physical work surface. The template shows exact positions of building elements with high visual precision, allowing workers to accurately transfer positions without the cumulative errors associated with manual tape measure measurements
Solution Approach 2:
The 3D projector system determines its six-DOF pose by scanning anchor targets with known CAD coordinates and comparing measured positions with model positions. This feedback loop allows the system to calculate transformation parameters and adjust the projected template pattern to account for surface irregularities and positioning errors, thereby improving measurement precision
3Manufacturing precision
If a separate crew uses total stations to accurately mark positions, then building elements can be positioned accurately, but the process requires additional personnel and increases operational complexity
Solution Approach 1:
The patent combines the functions of the 3D projector and total station into a single integrated device. The 3D projector includes both the laser projection capability for creating template patterns and the total station capability for measuring anchor targets and determining pose. This merging eliminates the need for a separate crew to operate independent total stations, reducing operational complexity while maintaining positioning accuracy
Solution Approach 2:
The 3D projector is designed as a multi-functional device that can both project glowing template patterns for visual guidance and perform total station measurements for accurate positioning. The single device serves multiple purposes: projecting templates, measuring anchor targets, calculating transformation parameters, and providing real-time positioning feedback, thereby eliminating the need for separate specialized equipment and crews
4Measurement precision
If the 3D projector determines six-DOF pose by scanning multiple anchor targets in multiple instances, then positioning accuracy is improved, but the calibration process requires multiple measurements and increases time consumption
Solution Approach 1:
The system performs preliminary scanning of multiple anchor targets in different instances to determine the six-DOF pose before actual template projection begins. By completing the pose determination and transformation parameter calculation in advance, the system prepares the accurate positioning information needed for subsequent rapid template projection, reducing time loss during the actual positioning operation
Solution Approach 2:
The 3D projector continuously scans anchor targets in multiple instances to gather measurement data for pose determination. Rather than performing discrete separate measurements, the system maintains continuous scanning action to collect sufficient data points for accurate six-DOF pose calculation, thereby improving measurement precision while minimizing idle time between measurements
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 rapid and accurate positioning of building elements by projecting a glowing template pattern onto a surface, aligning with CAD coordinates and accounting for surface irregularities, enhancing construction precision and efficiency.
Implementation Method 1
reflect the first beam of light off the first galvanometer mirror onto a second galvanometer mirror
Implementation Method 2
projecting a beam of light from a rangefinder to the point on the as-built surface
Data Source
AI summary
A method includes attaching a 3D projector to a stand, the 3D projector having a projecting mechanism and a gimbal mechanism; determining a six degree-of-freedom pose of the 3D projector based at least in part on steering at least one of the projecting mechanism and the gimbal mechanism to place the beam of light on each of a plurality of anchor targets in each of a first instance and a second instance, each anchor target having an anchor point with 3D coordinates known in a CAD model, each projection angle and gimbal angle to each of the plurality of anchor targets being different in first instance and the second instance.