Coordinate Transformation for AACMM and Scanner Fusion
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Solution Overview
Problem
Existing coordinate measurement devices, such as articulated arm coordinate measurement machines (AACMMs) and scanners, operate independently and use different coordinate frames, making it difficult to combine their measurements accurately, especially when AACMMs with contact-type probes need to measure objects with optical systems that use circular adhesive photogrammetry labels.
Innovation Solution
A method is developed to determine a common coordinate system by measuring three-dimensional coordinates of targets with both the AACMM and scanner, using a mathematical transformation characterized by a collection of parameters, allowing the AACMM and scanner to share a common reference frame for accurate data combination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different coordinate measurement devices (AACMM and scanner) are used to measure the same object, then measurement versatility is improved, but the difficulty of combining measurements accurately increases due to different coordinate frames
Solution Approach 1:
The patent introduces a common coordinate reference frame as an intermediary that mediates between the AACMM coordinate frame and the scanner coordinate frame. This intermediary reference frame allows both devices to measure the same physical points (using targets with reference points) and have their measurements reconciled through coordinate transformation, thereby enabling accurate combination of data from devices with different coordinate systems
Solution Approach 2:
The patent applies parameter changes by determining a mathematical transformation (characterized by a collection of parameters) that converts coordinates from one coordinate frame to another. By calculating transformation parameters based on measured positions of reference points on targets, the system adjusts the coordinate parameters to establish a common reference frame, enabling accurate data fusion between AACMM and scanner measurements
2Adaptability or versatility
If optical scanners use circular adhesive photogrammetry labels for registration, then optical measurement capability is improved, but the measurement precision decreases when AACMM contact probe measures these labels
Solution Approach 1:
The patent creates a copy of the reference point information by having both the AACMM and scanner measure the same physical reference points on targets. Instead of relying on optical reading of adhesive labels, the system uses the measured 3D positions of reference points from both devices to establish a common coordinate frame, thereby preserving measurement precision while maintaining optical measurement capability
Solution Approach 2:
The patent substitutes the optical reading mechanism (adhesive photogrammetry labels) with a mechanical measurement approach (contact probe measuring physical reference points). By replacing the optical recognition method with direct mechanical measurement of reference point positions, the system eliminates the precision loss associated with optical reading while maintaining the ability to register between coordinate systems
3Ease of operation
If AACMM and scanner operate independently with their own coordinate frames, then device operation simplicity is improved, but the measurement accuracy when combining data decreases
Solution Approach 1:
The patent performs preliminary action by establishing the common coordinate reference frame before combining measurements from AACMM and scanner. By first measuring reference points on targets and determining the mathematical transformation between coordinate frames in advance, the system prepares the necessary transformation parameters before actual measurement data fusion, thereby maintaining operational simplicity while ensuring measurement accuracy
Solution Approach 2:
The patent implements feedback by using the measured positions of reference points to determine and refine the coordinate transformation parameters. The system continuously adjusts and refines the transformation based on the feedback from reference point measurements, ensuring that the common coordinate frame accurately represents the physical space, thereby maintaining both operational simplicity and measurement accuracy
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 the use of AACMMs with contact-type probes to combine measurements with optical scanners, providing a common coordinate reference frame that allows for accurate and independent measurement of objects by both devices, improving measurement accuracy and efficiency.
Implementation Method 1
providing the scanner having a light projector and at least one camera, the light projector and the at least one camera arranged in a fixed geometric relationship, the light projector configured to project a structured light pattern
Data Source
AI summary
A method of determining a mathematical transformation to place three-dimensional (3D) coordinates of points measured by an articulated arm coordinate measurement machine (AACMM) and 3D points measured by a scanner in a common coordinate system is provided. The method including providing the 3D scanner and the AACMM having a probe. The scanner and AACMM each have a local frame of reference. Three non-collinear targets are measured with the probe and then with the scanner. 3D probe reference coordinates and 3D scanner reference coordinates are determined based on the measurement of the targets by the AACMM and scanner. The mathematical transformation is determined based at least in part on the 3D probe reference coordinates and the 3D scanner reference coordinates, the mathematical transformation characterized at least in part by a collection of parameters.