Marker-Based Pose Tracking for Precise 3D Surface Measurement
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Solution Overview
Problem
Existing automation systems, such as robotic arms, lack accuracy in positioning, which limits their use in precision tasks like metrology-level measurements, and rely on time-consuming and expensive retroreflector-based tracking systems.
Innovation Solution
A pose manipulation system coupled with a position measurement system uses photogrammetric markers and a camera-based 3D measurement device to record and track a path, allowing for accurate measurement of objects by interpolating poses based on pre-recorded paths, eliminating the need for absolute accuracy in the pose manipulation system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If retroreflector-based tracking systems are used to achieve high measurement accuracy, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses photogrammetric markers (2D or 3D patterns) as simplified copies of retroreflector targets. These markers can be captured by standard cameras rather than requiring complex laser trackers, maintaining measurement capability while reducing system complexity and cost. The markers are processed through photogrammetry to extract position and orientation information.
Solution Approach 2:
The patent replaces mechanical/laser-based tracking systems with an optical photogrammetry system. Instead of using laser trackers and retroreflectors, the system uses standard cameras to capture images of photogrammetric markers, process these images computationally to determine pose information, thereby substituting complex mechanical tracking with simpler optical capture and computational processing.
2Measurement precision
If pose manipulation system achieves high absolute positioning accuracy, then measurement precision is improved, but system cost and complexity increase
Solution Approach 1:
The patent performs preliminary calibration by recording the relationship between camera coordinates and object coordinates when the pose manipulation system is at known reference positions. This pre-recorded transformation data is then used to correct subsequent measurements, allowing the system to achieve high accuracy without requiring the pose manipulation system to have inherently high absolute positioning accuracy.
Solution Approach 2:
The patent introduces photogrammetric markers as intermediary objects that mediate between the camera and the target object. By capturing images of these markers and processing them through photogrammetry, the system obtains accurate position and orientation data without requiring the pose manipulation system itself to have high absolute accuracy, as the markers provide the reference framework.
3Ease of operation
If automation system uses operator-designated end positions, then ease of operation is improved, but measurement precision of intermediate points deteriorates
Solution Approach 1:
The patent continuously captures images of photogrammetric markers throughout the motion of the pose manipulation system, rather than only at discrete end positions. This continuous capture allows for interpolation and accurate determination of positions at all intermediate points along the trajectory, maintaining measurement precision while keeping the system easy to operate through simple end-position designation.
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
This approach enhances measurement accuracy and reliability, enabling repetitive measurements on similar objects with high precision without the need for expensive tracking systems, leveraging the repeatability of the pose manipulation system.
Implementation Method 1
uses photogrammetric markers and a camera-based 3D measurement device to record and track a path
Data Source
AI summary
A system includes a pose manipulation system operationally that sets a pose of a position measurement system with respect to an object that is to be measured. The system further includes a pose tracking system configured to record a relative pose between a coordinate system associated with the position measurement system and a coordinate system of the object. The pose tracking system records a path along which the position measurement system is enabled to measure 3D coordinates of a surface of a type of an object, wherein recording the path comprises moving the pose manipulation system sequentially through a plurality of poses and recording, at each pose, the relative pose to measure the 3D coordinates. The pose manipulation system follows the path again, and the position measurement system measures the 3D coordinates by applying one or more of the recorded poses.