THz Sensor Calibration for Pipe Thickness Measurement
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Solution Overview
Problem
Existing THz measuring apparatuses face challenges in accurately measuring layer thicknesses and diameters of extruded products like pipes, due to incorrect positioning and misalignment of THz sensors, which leads to reduced signal amplitude and incorrect measurements.
Innovation Solution
A calibrating method and apparatus that allows for individual pivoting of THz sensors arranged on a circular measuring receptacle, enabling precise adjustment of sensor axes to be perpendicular to the measurement object's surface, even for non-ideal shapes like oval pipes, without requiring translational adjustments of the entire measuring apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical adjustment means are used to position the measurement object or measuring apparatus, then positioning accuracy can be improved, but the complexity of the device increases and the adjustment process becomes time-consuming
Solution Approach 1:
The patent replaces mechanical adjustment systems with an optical calibration method. Instead of using motors, gears, or mechanical guides to position the measurement object or sensors, the invention uses THz radiation to detect positioning errors and calculates correction values. This substitution eliminates complex mechanical components while achieving high positioning accuracy through optical measurement and computational correction.
Solution Approach 2:
The patent creates a virtual model of the measurement object's position and shape based on THz radiation measurements. By measuring the actual position of boundary surfaces and comparing them with the ideal model, the system generates correction values without requiring physical mechanical adjustment. This copying approach allows digital correction of positioning errors, avoiding mechanical complexity.
2Measurement precision
If the entire THz measuring apparatus is adjusted relative to the measurement object, then measurement accuracy can be improved, but the time required for calibration increases and productivity decreases
Solution Approach 1:
The patent divides the calibration process into two independent segments: measurement object positioning calibration and sensor alignment calibration. Each segment can be performed separately and independently, allowing parallel processing or selective calibration. This segmentation reduces the total calibration time compared to adjusting the entire apparatus as a single unit, while maintaining comprehensive measurement accuracy.
Solution Approach 2:
The patent performs preliminary measurements to determine the actual position and shape of the measurement object before conducting the main measurement task. By using THz radiation to pre-calculate positioning errors and generate correction values in advance, the system eliminates the need for time-consuming mechanical adjustments during actual operation, thereby improving productivity while ensuring measurement accuracy.
3Adaptability or versatility
If THz sensors are fixed in position on the measuring receptacle, then the device complexity is reduced, but the ability to adapt to non-ideal measurement objects like oval pipes is lost
Solution Approach 1:
The patent replaces mechanical sensor adjustment mechanisms with a computational approach. Instead of providing motors or mechanical means to physically reposition sensors for different object shapes, the invention uses THz radiation measurements to detect positioning deviations and calculates correction values. This allows the fixed sensor array to adapt to various shapes including oval pipes through digital correction, eliminating the need for complex mechanical adjustment mechanisms.
Solution Approach 2:
The patent changes the operational parameters of the measurement system by introducing correction values that compensate for positioning errors. Rather than physically altering the sensor positions or measurement object alignment, the system modifies the measurement parameters through calculated corrections, enabling adaptation to different object geometries while keeping the hardware configuration simple and fixed.
4Measurement precision
If perpendicular signal coupling is used to maximize reflected signal feedback, then measurement precision is improved, but the system becomes sensitive to angular misalignments causing signal loss
Solution Approach 1:
The patent implements a feedback mechanism where THz radiation measurements are used to detect angular misalignments and positioning errors. The system continuously monitors the reflected signal characteristics, compares them with ideal perpendicular coupling conditions, and generates correction values to compensate for deviations. This feedback loop maintains high signal feedback strength while compensating for angular misalignments, thereby improving measurement reliability without sacrificing precision.
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 solution enables quick and secure calibration of the THz measuring apparatus, allowing for high-precision measurement of distances and layer thicknesses across the entire circumference of pipes, even with deformations like ovalities, without causing measurement errors.
Implementation Method 1
The transmitted THz beams of the individual THz sensors are each partially reflected at the boundary surfaces of the layers so that the reflected THz beams reflected perpendicularly back towards the THz sensors can be detected
Implementation Method 2
making it possible to determine distances and layer thicknesses from a time of flight of the THz radiation
Data Source
AI summary
The invention relates to a method for calibrating a THz measuring apparatus (8), in particular a pipe, on a measurement object (10), comprising at least the following steps: providing a THz measuring apparatus (8) having a plurality of pivotable THz sensors (1), arranged in a circumferential direction around a measuring chamber (9), for outputting one THz transmitted beam (12) each along a sensor axis (B) (provision step); orienting the THz sensors (1) into a starting position in the measuring chamber (9) in which the measurement object (10) is received (orientation step in starting position); allocating the THz sensors (1) to at least one first and one second sensor group (group formation step); first calibration adjustment step, in which the second sensor group is adjusted as an adjustment group by means of the first sensor group as a starting group, and corresponding second calibration adjustment step, in which the first sensor group is adjusted as an adjustment group by means of the previously calibration-adjusted second sensor group as a starting group; wherein, in each of the calibration adjustment steps=by means of the THz sensors (S1, S3, S5, S7) of the starting group, spacing points on a surface (10a) of the measurement object (10) are determined, =sensor correction angles of the THz sensors (1; S2, S4, S6, S8) of the adjustment group are determined by means of the spacing points determined by the starting group, and =the THz sensors of the adjustment group are calibration-adjusted about the determined sensor correction angles (a).