Optical Tracking Calibration for NDT Sensor-Holder Alignment
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Solution Overview
Problem
Existing methods for determining the transformation matrix between a sensor holder and a sensor in non-destructive testing are cumbersome, time-consuming, and prone to handling errors, making it difficult to accurately position and orient the sensor for comprehensive scanning.
Innovation Solution
A calibration method and device using an optical motion tracking system, a calibration block, and mathematical transformations to quickly and accurately determine the transformation matrix between the sensor holder and sensor, incorporating steps to measure the calibration block and sensor dimensions and align reference frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional methods are used to determine the transformation matrix between sensor holder and sensor, then the calibration can be performed, but the process is time-consuming and prone to handling errors
Solution Approach 1:
The patent applies preliminary action by pre-defining reference frames on both the sensor holder and sensor before calibration. The reference frame on the sensor holder is established beforehand with known transformation relationships, allowing the calibration process to simply determine relative positions rather than establishing all transformations from scratch. This pre-preparation significantly reduces calibration time while maintaining accuracy.
Solution Approach 2:
The patent introduces an intermediary reference frame system that mediates between the sensor holder and sensor. By using a common reference frame coordinate system that both components can relate to, the complex direct transformation determination is simplified into two easier sub-problems: sensor holder to reference frame, and sensor to reference frame. This intermediary approach reduces handling errors and improves precision.
2Measurement precision
If traditional calibration methods are used, then the transformation matrix can be determined, but handling errors increase and accuracy decreases
Solution Approach 1:
The patent replaces manual mechanical alignment and measurement methods with a mathematical coordinate system approach. Instead of physically aligning components and measuring positions manually (which introduces handling errors), the system uses defined reference frames and mathematical transformations to determine positions. This substitution of mechanical operations with mathematical calculations eliminates handling errors and improves both accuracy and reliability.
Solution Approach 2:
The patent changes the calibration approach from measuring physical positions directly to working with coordinate system parameters. By transforming the problem from physical space measurement to coordinate system parameter determination, the method reduces sensitivity to handling errors. The reference frame parameters provide a stable mathematical basis that is independent of physical manipulation errors.
3Measurement precision
If a transformation matrix is determined for each new sensor and sensor holder combination, then accurate positioning is achieved, but the calibration process becomes complex and difficult
Solution Approach 1:
The patent applies universality by creating a universal reference frame system that can accommodate any sensor and sensor holder combination. Instead of developing unique calibration procedures for each component pair, the system uses a common reference frame coordinate system that serves as a universal intermediary. This universal approach simplifies the calibration process while maintaining accurate positioning for all combinations.
Solution Approach 2:
The patent segments the calibration problem into two independent, simpler sub-problems: determining the sensor holder's position relative to the reference frame, and determining the sensor's position relative to the reference frame. This segmentation breaks down the complex direct transformation problem into manageable parts that can be solved separately and then combined, reducing overall process complexity.
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, precise calibration of the sensor holder and sensor, ensuring complete scanning of the examination area with minimized errors, and supports real-time visualization of non-destructive testing signals through augmented reality.
Implementation Method 1
an optical motion tracking system to which a reference frame (R0) is linked
Implementation Method 2
Non-destructive testing by ultrasound is a non-invasive method of detecting defects in a part, based on the emission of ultrasound and the detection of their reflection linked to the acoustic interfaces encountered
Data Source
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AI summary
The invention relates to a method for calibrating a device for non-destructive testing of a mechanical part, the device comprising: - an optical movement tracking system to which a reference mark is linked; - a sensor holder; - a first rigid body; - a non-destructive testing sensor secured to the sensor holder and fixedly connected to the first rigid body; and - a computer, the method being characterised in that it comprises the following steps: - determining (100), from three points on an upper planar surface of a calibration block, the length and width of the calibration block; - determining (110) a first matrix for transforming the reference mark into a mark of the block linked to the calibration block; - arranging (115) the sensor on the upper planar surface of the calibration block; - determining (120), from three points on the first rigid body, the length and width of the sensor; and - determining (130) a second transformation matrix making it possible to pass from a mark linked to the sensor holder to a mark linked to the sensor.