Range Finder Brightness Saturation Correction
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Solution Overview
Problem
Optical range finding devices face accuracy issues when measuring distances due to intensity-modulated signals being detected in non-linear regions of the brightness sensitivity characteristic of image capturing units, leading to errors in synchronous detection and object distance measurement.
Innovation Solution
A range finding device and method that includes a light projecting unit, an image capturing unit, a light projection controller, a synchronous detection unit, and a range calculator, which control the intensity of the irradiation light to shift brightness changes into a linear region, allowing accurate detection of the synchronous detection region and calculation of object distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If intensity-modulated irradiation light is projected to enhance robustness against noise, then measurement reliability is improved, but the brightness output value may fall into a non-linear region of the image capturing unit, causing saturation and detection errors
Solution Approach 1:
The system performs preliminary synchronous detection to determine whether the brightness output value is in a linear or non-linear region before final measurement. Based on this preliminary assessment, the irradiation light intensity is adjusted in advance to ensure subsequent measurements fall within the linear region, preventing saturation errors.
Solution Approach 2:
The system uses feedback from the synchronous detection result to dynamically adjust the irradiation light intensity. When non-linear region detection is identified, the light intensity is reduced and re-projected, creating a closed-loop control system that ensures measurements always occur within the linear region of the image capturing unit.
2Reliability
If the amplitude of irradiation light is increased to improve signal strength, then detection robustness is improved, but the upper end portion of the brightness output signal becomes saturated in the non-linear region
Solution Approach 1:
The system dynamically adjusts the amplitude of irradiation light based on real-time detection of the brightness output region. Instead of using a fixed high amplitude, the system modulates the light intensity adaptively, increasing it when in the linear region and decreasing it when approaching saturation, thereby maintaining optimal detection conditions throughout the measurement process.
3Reliability
If the intensity of irradiation light is modulated to enhance signal detection, then measurement reliability is improved, but the change in brightness may fall into a non-linear region causing errors in synchronous detection judgment
Solution Approach 1:
The system performs a preliminary detection pass to assess whether the modulated brightness signal falls within the linear region. Based on this preliminary assessment, it determines the appropriate irradiation intensity level before conducting the actual distance measurement, ensuring that the synchronous detection operates within the linear region for accurate results.
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
Enhances the accuracy of distance measurement to objects by correcting amplitude and direct current components of the irradiation light, preventing detection failures and ensuring robust synchronous detection even in non-linear brightness output regions.
Implementation Method 1
irradiate an object with irradiation light; capture reflected light reflected off the object with an image capturing device such as a CCD
Data Source
Figure 1~2
Figure 3~4(d)
Figure 5~6
AI summary
A range finding device (100) includes: a light projecting unit (11) mounted on a moving body, having an irradiation domain extending in a horizontal direction, and configured to project intensity-modulated irradiation light; an image capturing unit (12) mounted on the moving body, and configured to capture an image of an object (P) irradiated with the irradiation light; a light projection controller (13) configured to control an intensity of the irradiation light in accordance with a timing at which the image capturing unit captures the image; a synchronous detection unit (14, 15, 18) configured to extract a synchronous detection region, in which brightness changes in synchronism with intensity modulation of the irradiation light, from the image captured by the image capturing unit; an edge detector configured to detect an edge of the synchronous detection region; and a range calculator configured to calculate a distance to the object on the basis of the edge of the synchronous detection region detected by the edge detector. If the change in the brightness of the image brings about a brightness output value in a non-linear region of the image capturing unit, the synchronous detection unit (18) calculates an amplitude and a direct current component of the irradiation light needed to shift the change in the brightness of the image to a linear region of the image capturing unit. The light projection controller (13) controls the intensity of the irradiation light on the basis of the calculated amplitude and direct current component of the irradiation light.