Dual Rolling-Shutter Cameras for ADAS Stereo Synchronization
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Solution Overview
Problem
Existing camera systems for Advanced Driver Assistance Systems (ADAS) face challenges in spatial reconstruction due to limited camera spacing, exposure time differences, and motion blur, particularly when using rolling shutter cameras with different optics or image sensors, leading to artifacts and errors in triangulation.
Innovation Solution
A camera system comprising a wide-angle and tele camera with rolling shutter technology, where the cameras are synchronized by adjusting their exposure times and clock frequencies to ensure simultaneous exposure of overlapping regions, with the control electronics determining and utilizing the geometric arrangement and position to minimize exposure discrepancies and distribute motion blur evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If two cameras with different optics or image sensors are used to increase field of view coverage, then the area of stationary object is improved, but the measurement precision deteriorates due to exposure time differences and motion blur
Solution Approach 1:
The patent implements dynamic synchronization by continuously adjusting the exposure timing of the wide-angle and telephoto cameras based on their respective rolling shutter characteristics. The control unit calculates and applies different exposure start times and exposure durations for each camera to ensure that corresponding image regions are captured at the same moment, thereby eliminating motion blur discrepancies while maintaining different fields of view.
Solution Approach 2:
The patent changes the exposure parameters (exposure start time and exposure duration) of the two cameras dynamically. By adjusting these parameters based on the rolling shutter characteristics and relative positions of the cameras, the system ensures simultaneous capture of corresponding regions without requiring identical exposure settings, thus resolving the contradiction between different optics and measurement precision.
2Area of stationary object
If rolling shutter cameras with different exposure times are used, then the area of stationary object is improved, but the reliability deteriorates due to artifacts in correspondence finding and triangulation errors
Solution Approach 1:
The system dynamically adjusts the exposure timing parameters for each camera based on their rolling shutter characteristics. The control unit continuously synchronizes the exposure moments by calculating appropriate time offsets, ensuring that corresponding image regions are captured simultaneously. This dynamic synchronization eliminates artifacts in correspondence finding and triangulation errors, maintaining high reliability while using cameras with different exposure times.
Solution Approach 2:
The patent implements a feedback mechanism where the control unit continuously monitors and adjusts the exposure timing of both cameras. By calculating the actual exposure moments and comparing them against the desired synchronization, the system dynamically corrects timing discrepancies, thereby eliminating artifacts and ensuring reliable stereo reconstruction.
3Measurement precision
If global shutter technology is used to achieve simultaneous exposure of all photosensitive elements, then the measurement precision is improved, but the device complexity and cost increase
Solution Approach 1:
The patent creates a virtual global shutter effect by using the existing rolling shutter cameras with synchronized exposure timing. Instead of replacing the rolling shutter cameras with expensive global shutter cameras, the system calculates and applies appropriate exposure time offsets to simulate simultaneous capture across all photosensitive elements, thereby achieving the same effect with simpler, less costly hardware.
Solution Approach 2:
The system changes the exposure timing parameters of the rolling shutter cameras to achieve simultaneous exposure of corresponding regions. By dynamically adjusting the exposure start times and durations based on the rolling shutter characteristics and camera positions, the system replicates the functionality of global shutter technology without requiring the complex hardware associated with it.
Data Source
AI summary
A camera system and method for controlling same, including capturing images of surroundings of a vehicle for a driver assistance system thereof. The camera system includes a first rolling shutter camera having a first aperture angle, a second rolling shutter camera having a second aperture angle, and control electronics. The first and second cameras are suitable for generating wide-angle and tele camera images, respectively. The first aperture angle is greater than the second aperture angle. The two cameras are designed such that both camera images have an overlap region. The control electronics synchronizes the two cameras. The geometric arrangement of the two cameras with respect to one another, and the position of the overlap region in the wide-angle image and in the tele camera image, are determined by continuous estimation. The stored geometric arrangement and position are taken into consideration during synchronization of the first and second cameras.