Non-contact Sheet Thickness Measurement Using Optical Triangulation
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Solution Overview
Problem
Existing non-contact sheet material thickness measurement systems suffer from low measurement accuracy due to poor control of the x,y position alignment of optical displacement sensors and difficulties in controlling the angle of the sheet material relative to the x,y plane, leading to inaccuracies in thickness measurement, especially when dealing with fragile or coated sheets.
Innovation Solution
The system employs optical displacement sensors configured to emit along lines that are offset in the x,y plane by about 90° relative to each other, with a computing device determining the projected intersection point to calculate the sheet material thickness accurately, even when the sheet is moving, using x,y position sensors and a z-position sensor to ensure precise alignment and distance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contacting thickness sensors are used to measure sheet material thickness, then thickness measurement can be performed, but the sheet material may be damaged or the sensor may be damaged due to physical contact
Solution Approach 1:
The patent replaces mechanical contact-based thickness sensors with an optical measurement system using laser triangulation sensors. The system uses optical beams to measure thickness without physical contact, eliminating damage to both the sheet material and sensors while maintaining measurement capability
2Object-affected harmful factors
If non-contact optical displacement sensors are used for thickness measurement, then damage to sheet material and sensors is avoided, but measurement accuracy is insufficient
Solution Approach 1:
The patent implements feedback control by continuously monitoring the x,y position of optical displacement sensors and dynamically adjusting their positions to maintain alignment. The system uses position feedback from encoders and active feedback mechanisms to ensure the measurement beams remain properly aligned on the moving sheet material, thereby achieving high measurement accuracy without physical contact
Solution Approach 2:
The patent makes the optical displacement sensor positions dynamic rather than fixed. The system continuously adjusts sensor positions in real-time to track and maintain alignment with the moving sheet material, enabling accurate measurements on moving webs while avoiding contact-related damage
3Object-affected harmful factors
If optical displacement sensors are positioned on opposite sides of sheet material, then non-contact measurement is achieved, but poor x,y position alignment control reduces measurement accuracy
Solution Approach 1:
The patent uses feedback control to continuously monitor and adjust the x,y positions of optical displacement sensors. Position encoders provide feedback on sensor locations, and active feedback mechanisms dynamically adjust sensor positions to maintain precise alignment with the sheet material, achieving both non-contact measurement and high positional 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
This configuration enables highly accurate on-line sheet material thickness measurements, reducing the risk of damage to the sensors and improving measurement precision, making it suitable for various sheet materials, including fragile and coated ones, by ensuring perfect x,y position alignment and accurate angle control.
Implementation Method 1
optical displacement sensors (e.g., triangulation sensors) that are each configured to emit along a line
Data Source
AI summary
A non-contact thickness measurement system includes a first optical displacement sensor in a first scanner head and a second optical displacement sensor in a second scanner head on opposite sides of a sheet material. The displacement sensors measure a plurality of distances to a first line in a first direction along the top of the material and plurality of distances to a second line in a second direction along a bottom of the material. An x,y position sensor determines x,y position data. A z-position sensor measures a sensor-to-sensor distance. A computing device determines a projected intersection point of the first and second lines, and using the projected intersection point selects a first distance from the distances from first displacement sensor and a second distance from the distances from the second displacement sensor, and for calculating a sheet material thickness using the first distance, second distance, and the sensor-to-sensor distance.