Displacement Measurement Device Nonlinear Error Correction
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Solution Overview
Problem
Displacement measurement devices face challenges in accurately measuring distances due to nonlinear errors caused by interference from thin films and wavelength dispersion through transparent members, such as glass, which complicates correction across the entire measurement range using a single linear function.
Innovation Solution
A displacement measurement device with a light projecting unit, sensor head, storage unit, and control unit that generates and corrects measured values using continuous linear functions based on the wavelength of the light beam received, accounting for nonlinear errors from interference and wavelength dispersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If correction is performed with a reference workpiece during production, then linearity between distance and measured value is secured, but the relationship between distance and measured value becomes nonlinear when used with different workpieces
Solution Approach 1:
The patent changes the correction approach from using a single linear function to using multiple linear functions with different parameters (slopes and intercepts) corresponding to different measurement ranges. This allows the system to adapt to different workpieces and measurement conditions while maintaining high precision across the entire measurement range.
Solution Approach 2:
The patent divides the measurement range into multiple sections and applies different linear correction functions to each section. This segmentation approach allows the system to handle the nonlinear relationship between distance and measured value by treating each segment separately, thereby improving overall measurement accuracy for different workpieces.
2Device complexity
If a single linear function is used to correct the entire measurement range, then the correction process is simple, but it is difficult to reduce nonlinear errors across the entire range
Solution Approach 1:
The measurement range is divided into multiple sections, each with its own linear correction function. This segmentation enables the system to reduce nonlinear errors effectively across the entire range while keeping each individual correction function simple and manageable.
Solution Approach 2:
Instead of attempting to correct the entire measurement range with a single linear function, the patent applies multiple linear functions to different portions of the range. This partial action approach allows for more precise correction in each section without overcomplicating the overall system.
3Ease of operation
If measurement is performed through a transparent member such as glass, then distances can be measured, but wavelength dispersion causes the relationship between distance and detection wavelength to differ
Solution Approach 1:
The patent accounts for wavelength dispersion by using linear correction functions with parameters that are specific to each measurement section and transparent member. This allows the system to maintain measurement precision even when measuring through glass or other transparent members by adjusting the correction parameters accordingly.
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 high-accuracy distance measurement by correcting nonlinear errors through the use of pre-generated linear functions, effectively addressing interference and wavelength dispersion issues in thin films and transparent members.
Implementation Method 1
a sensor head configured to emit the light beam to a measurement target object of which a measured value and an actual displacement are nonlinear so that a focus is formed on a measurement target surface of the measurement target object and receive a light beam that is reflected at the measurement target surface
Implementation Method 2
when a distance to a measurement target surface of a measurement target object is measured through a transparent member such as a glass, a refractive index by which wavelength dispersion occurs makes the relationship between a distance and a detection wavelength differs
Implementation Method 3
a displacement measurement device using a white confocal method as a measurement method is known. According to such a displacement measurement device, it is possible to measure a distance to a measurement target object (specifically, a measurement target surface) based on a wavelength of a received light beam
Data Source
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AI summary
A displacement measurement device (2) and a measurement method are provided. A displacement measurement device (2) includes a light projecting unit (12) configured to generate a light beam; a sensor head (20) configured to emit the light beam to a measurement target object and receive a light beam reflected at the measurement target surface within the emitted light beam; a storage unit (16) configured to store a function using a distance between the sensor head (20) and the measurement target surface as a variable; and a control unit (11) configured to calculate the distance based on wavelength of the received light. The control unit (11) calculates a value of the function using a distance between the sensor head (20) and the measurement target surface of the measurement target object as a value of the variable. The control unit (11) corrects the calculated distance using the calculated value of the function.