Mudguard Edge Measurement with Shifted Light Patterns
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Solution Overview
Problem
Existing methods for determining the position and orientation of a vehicle's fender edge in a test bench require high point densities in the 3D point cloud, leading to prolonged computing times that negatively impact cycle times, especially in vehicle production.
Innovation Solution
A method involving the projection of a constant light pattern divided into unique sub-areas, vibration of the lighting unit or its components to shift the pattern, and stereophotogrammetric determination of a 3D point cloud, followed by identifying a subset of points within defined volumes to enhance point density and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high point density is used in the 3D point cloud to improve measurement accuracy, then measurement precision is improved, but computing time increases and productivity deteriorates
Solution Approach 1:
The light pattern is divided into multiple sub-patterns that are projected sequentially onto the fender edge. Each sub-pattern captures a specific region, allowing the system to process smaller data portions separately. This segmentation reduces the computational burden while maintaining comprehensive coverage of the measurement area, thus improving productivity without sacrificing measurement precision.
Solution Approach 2:
The projection of light patterns is performed periodically in sequences rather than continuously. By projecting multiple sub-patterns in a periodic sequence and capturing images at specific intervals, the system optimizes the balance between data quality and processing time. This periodic approach allows for efficient computation while maintaining high measurement accuracy through multiple sampling opportunities.
2Measurement precision
If high point density is used in the 3D point cloud to improve measurement accuracy, then measurement precision is improved, but computation time increases
Solution Approach 1:
The evaluation process is segmented into multiple steps where different subsets of point cloud data are processed at different stages. Initially, a first subset with lower computational requirements is evaluated to obtain preliminary results, then a second subset is processed to refine the measurement. This segmentation reduces total computation time while maintaining high measurement accuracy through progressive refinement.
Solution Approach 2:
The system processes multiple subsets of point cloud data beyond what a single comprehensive processing would require. By evaluating multiple smaller subsets (first subset, second subset, and their combinations), the system achieves higher measurement accuracy through redundant verification while managing computation time through efficient processing strategies and early termination when sufficient accuracy is achieved.
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 increases measurement accuracy and reduces computation time by enhancing point density in the 3D point cloud, allowing for faster and more efficient determination of the fender edge's position and orientation.
Implementation Method 1
two imaging units for recording the light pattern currently projected onto the vehicle body. A 3D point cloud is determined from the images recorded by the two imaging units
Implementation Method 2
shifting the light pattern projected onto the vehicle body by exciting a vibration of the lighting unit or at least one component of the lighting unit
Data Source
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AI summary
The present invention relates to a method for measuring the mudguard edge of a vehicle on a test bench, wherein the test bench has a coordinate system in which the Z axis is the vertical axis, the X axis is an axis in the test bench extending in the horizontal plane in the longitudinal direction of a vehicle for testing on the test bench, and the Y axis is an axis of the test bench extending perpendicular to the X axis in the horizontal plane. Within the scope of the invention, it is proposed to shift a light pattern projected onto a vehicle by an illumination unit and to record this light pattern by means of two imaging units. The 3D point clouds determined stereophotogrammetrically from the recordings are used to form a subset for evaluation. This procedure allows higher measurement rates when determining the position and orientation of the mudguard edge.