Phase Shift Distance Measurement Filtering Saturated Signals
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Solution Overview
Problem
The phase shift method for distance measurement is prone to errors due to saturated luminance or low contrast in received light signals, often resulting from defective emission, outside light interference, or light receiving element malfunctions, leading to inaccurate distance calculations.
Innovation Solution
A distance measurement apparatus and method that calculates distance information only from light receiving elements with an absolute value difference between specific added signals at different phases below a threshold, ensuring accurate distance measurement by filtering out inappropriate received light signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the phase shift method is used to measure distance, then distance information can be obtained, but erroneous measurements occur due to saturated luminance or low contrast in received light signals
Solution Approach 1:
The patent applies preliminary action by calculating a reliability indicator for each light receiving element before performing distance measurement. The system evaluates the absolute value of the difference between first and second added signals in advance, compares it against a threshold, and identifies unreliable elements beforehand. This preliminary assessment prevents erroneous measurements from affecting the final distance calculation, thereby resolving the contradiction between measurement precision and reliability.
2Area of stationary object
If received light signals from all light receiving elements are used for distance calculation, then measurement coverage is maximized, but inaccurate measurements result from defective emission, outside light interference, or element malfunctions
Solution Approach 1:
The patent applies local quality by treating each light receiving element individually with a localized quality assessment. The reliability indicator calculation is performed separately for each element based on its specific received light signals. Elements with poor signal quality (high absolute difference between added signals) are identified and excluded locally, while elements with good signal quality continue to contribute to the distance measurement. This selective approach maintains measurement coverage while ensuring 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
Prevents erroneous distance measurements by ensuring that only reliable light receiving elements contribute to distance calculations, thereby improving the accuracy of distance information obtained.
Implementation Method 1
an imaging unit which includes an image sensor having a plurality of light receiving elements, disposed two-dimensionally, for receiving reflected light of the stripe pattern light reflected from the subject and outputting a received light signal according to the amount of light received
Data Source
AI summary
Emitting stripe pattern light, whose intensity changes periodically, onto a subject while shifting the phase of the pattern by π/2 from a reference phase of 0 until the phase is shifted one cycle to receive reflected light by an image sensor at each of phases 0, π/2, π, and 3π/2. From received light signals obtained at four phases, calculating a phase difference between the stripe pattern light and reflected light thereof with respect to each light receiving element to calculate distance information representing a distance to the subject based on the phase difference. In this case, the distance information is calculated only from a light receiving element having an absolute value of the difference between a first added signal of received light signals at 0 and π and a second added signal of received light signals at π/2 and 3π/2 smaller than a specific value.