Distance Measuring Sensor Fusing Phase Difference and Triangulation
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Solution Overview
Problem
Conventional distance measuring devices using the indirect time of flight method face challenges in accurately measuring distances to moving objects due to errors generated during the image generation process.
Innovation Solution
A distance measuring system that employs a distance measuring sensor to generate images from pulse train pattern light, detects bright regions, calculates distance using phase difference and triangulation, and fuses these measurements to reduce errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the four-phase indirect ToF method is used to measure distance, then noise can be removed by calculating differences between images, but measurement error increases when the object moves during image generation
Solution Approach 1:
The patent applies dynamics by making the measurement system adaptable to object movement. Instead of using a fixed four-phase method that assumes stationary objects, the system dynamically adjusts by selecting images with the smallest time intervals between them, allowing the measurement process to adapt to moving objects and maintain reliability.
Solution Approach 2:
The patent changes the parameter of image selection criteria from fixed phase intervals (0, 90, 180, 270 degrees) to variable selection based on time intervals. The system calculates time intervals between multiple captured images and selects combinations with the smallest intervals, thereby changing the measurement parameter to optimize for moving objects.
2Measurement precision
If multiple images are captured at different phases to perform synchronous detection, then phase difference can be detected accurately, but the measurement period increases making it difficult to track moving objects
Solution Approach 1:
The patent applies partial action by not requiring all four phase images to be used for measurement. Instead, the system captures multiple images and selectively uses only those with the smallest time intervals, performing partial synchronous detection that reduces measurement time while maintaining sufficient accuracy for moving objects.
Solution Approach 2:
The patent performs preliminary selection of images based on time intervals before actual distance calculation. By pre-identifying and selecting the most suitable image combinations, the system prepares the optimal measurement set in advance, reducing the overall measurement period needed to track moving objects.
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 system effectively reduces measurement errors for moving objects by combining phase difference and triangulation methods, enhancing accuracy and reliability.
Implementation Method 1
a light emitting unit that emits amplitude-modulated light to an object and a light receiving element that receives reflected light obtained by reflecting emitted light by the object
Implementation Method 2
The imaging element generates multiple image signals by performing synchronous detection synchronized with the amplitude-modulated emitted light on the received reflected light
Implementation Method 3
The phase difference between the emitted light and the reflected light can be detected by mutual calculation of the multiple generated image signals
Data Source
AI summary
An error in distance measurement is reduced. The distance measuring sensor generates multiple images by receiving light in light reception periods that are synchronized with pulse train pattern light, which repeats a light emission period and a non-light emission period of two types of luminance of a bright portion and a dark portion, and have different phases from each other. A bright region detecting unit detects a bright region which is a region generated by receiving reflected light corresponding to the bright portion of the pattern light in each of the multiple images. A first distance measuring unit detects a phase difference between the emitted pattern light and the reflected light on the basis of the bright regions detected in the multiple images and calculates a first distance measurement value that is a distance to the object on the basis of the detected phase difference. A bright region selecting unit selects among the bright regions, detected in the multiple images, on the basis of image signals constituting the images. A second distance measuring unit calculates a second distance measurement value that is a distance to the object by triangulation using a position of the selected bright region in the image. A fusion unit generates a fused distance measurement value by fusing the first distance measurement value and the second distance measurement value.