Optical Distance Data Correction for Doppler-Shifted 3D Measurement
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Solution Overview
Problem
Optical distance meters using frequency-shifted feedback lasers experience reduced measurement accuracy due to Doppler shifts caused by the relative velocity between the light source and the object being measured, especially when measuring three-dimensional geometries by moving the object or the measurement apparatus.
Innovation Solution
A data correction apparatus that corrects measurement errors by applying a recurrence formula based on the time derivative of the measurement results, using a frequency-modulated laser beam to account for Doppler shifts without requiring additional velocity measurement systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the optical distance meter measures distance by moving the object or measurement apparatus to capture three-dimensional geometry, then the measurement coverage and geometric information are improved, but measurement accuracy deteriorates due to Doppler shifts
Solution Approach 1:
The patent applies feedback by using the time derivative of measurement results to correct Doppler shift errors. The correction unit continuously adjusts the measured distance data based on the rate of change of measurements, creating a feedback loop that compensates for motion-induced frequency shifts and maintains measurement accuracy during movement.
Solution Approach 2:
The patent changes the parameter being measured from raw distance values to the time derivative of distance values. By measuring and correcting based on the rate of change rather than absolute position, the system can account for motion effects and maintain accuracy while the object or apparatus moves through three-dimensional space.
2Measurement precision
If a velocity measurement system is added to correct Doppler shifts, then measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent implements self-service by using the distance measurement data itself to correct Doppler shift errors. The measurement system generates its own correction data through the time derivative calculation, eliminating the need for external velocity sensors or additional measurement systems. The system serves its own correction needs using only its existing measurement capabilities.
Solution Approach 2:
The patent introduces the time derivative as an intermediary between raw distance measurements and corrected distance values. Rather than directly measuring velocity with additional hardware, the system uses the rate of change of distance measurements as an intermediate parameter to calculate and apply Doppler corrections, simplifying the overall system architecture.
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
The data correction apparatus effectively reduces measurement errors caused by Doppler shifts, ensuring accurate three-dimensional geometry measurements without increasing the apparatus' complexity or cost.
Implementation Method 1
since light has a wave-like nature and a Doppler shift occurs due to a relative velocity between a light source and the object to be measured, the frequency of the reflected light reflected from the object to be measured may change
Implementation Method 2
A laser apparatus 110 outputs a frequency-modulated laser beam. A branching part 120 splits the frequency-modulated laser beam output from the laser apparatus 110 into (i) a reference light, which is a portion of the frequency-modulated laser beam, and (ii) a measurement light
Implementation Method 3
a beat signal generation part 150 that generates a beat single by mixing the reference light and a reflected light that is reflected by radiating the measurement light onto an object to be measured
Data Source
AI summary
A data correction apparatus including an acquisition part that acquires, from a measurement apparatus capable of periodically measuring a distance while moving at least one of (i) an object to be measured or (ii) at least a part of the measurement apparatus, measurement data in which a first measurement result of the distance is arranged in time series and a second measurement result that is obtained by measuring the distance when the object to be measured and the measurement apparatus are in a stationary state is arranged at a head or a tail of the first measurement result, and a correction part that corrects an error included in the measurement data by applying the measurement data to a recurrence formula based on a time derivative of a measurement result of the measurement apparatus.