Indirect ToF Distance Calibration Using Multi-Frequency Phase
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Solution Overview
Problem
Conventional calibration methods for obtaining correction parameters in indirect Time-of-Flight (ToF) distance measurement devices require a known distance and precise setup, making it difficult to calibrate in actual use environments.
Innovation Solution
A distance measuring device that uses multiple light emission frequencies and phase difference calculations to obtain correction parameters, allowing calibration even when the distance to the target object is indefinite, and includes features for eliminating 2π indefiniteness and recalibrating over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration methods using known distance are employed, then correction parameters can be obtained, but calibration cannot be performed in actual use environments
Solution Approach 1:
The patent changes the calibration approach by using multiple light emission frequencies (first frequency f1 and second frequency f2) instead of relying on known distance. By measuring phase differences at different frequencies and using the relationship between frequency, wavelength, and phase, the system can calculate correction parameters without requiring a precisely positioned target at a known distance, enabling calibration in actual use environments.
2Adaptability or versatility
If multiple light emission frequencies are used for calibration, then calibration can be performed in actual use environments, but calculation complexity increases
Solution Approach 1:
The patent segments the calibration process into distinct frequency measurements (first frequency f1 and second frequency f2), where phase differences are measured separately at each frequency. This segmentation allows the complex multi-frequency problem to be broken down into manageable sequential measurements, simplifying the overall calculation process while still enabling calibration without known distance.
Solution Approach 2:
The system uses feedback from phase difference measurements at multiple frequencies to iteratively determine correction parameters. By comparing phase differences obtained at different frequencies and using the known relationship between frequency and wavelength, the system refines correction parameters through feedback loops, managing calculation complexity through systematic feedback processing.
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 calibration in real-world environments, maintains accuracy by adjusting for changes in correction parameters, and improves distance measurement precision by using phase differences and specific positional relationships between measurement points.
Implementation Method 1
a light receiving sensor that receives the light emitted from the light emitting unit and reflected by a target object
Implementation Method 2
distance measurement is performed by emitting sine wave light and receiving light that has hit and been reflected by a target object
Data Source
AI summary
A distance measuring device according to a technology includes a light emitting unit that emits light, a light receiving sensor that receives the light emitted from the light emitting unit and reflected by a target object, and a calibration calculation unit that performs, as calibration calculation processing for obtaining a correction parameter for distance information calculated by an indirect ToF method on the basis of a light reception signal of the light receiving sensor, calculation processing using a light reception signal of the light receiving sensor when the light emitting unit performs light emission at a first light emission frequency and a light reception signal of the light receiving sensor when the light emitting unit performs light emission at a second light emission frequency different from the first light emission frequency.