Stereo Camera Exposure Timing Control for Rolling-Shutter Ranging
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Solution Overview
Problem
When using rolling-shutter type cameras for vehicle-mounted systems, exposure timing differences between multiple cameras lead to ranging errors due to changes in the relative positions of the vehicle and the ranging target during image capture, complicating the measurement of three-dimensional information.
Innovation Solution
A vehicle-mounted control device adjusts the exposure timing of rolling-shutter type cameras based on the ranging position to synchronize image capture, using a ranging unit and exposure timing adjusting unit to align the imaging start times of multiple cameras, thereby suppressing ranging errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If rolling-shutter type cameras are used for vehicle-mounted systems, then cost and ease of manufacture are improved, but exposure timing differences between multiple cameras cause ranging errors
Solution Approach 1:
The patent changes the exposure timing parameter of rolling-shutter type cameras to achieve synchronization. Specifically, it adjusts the start timing of image capture for each camera based on the baseline distance and vehicle speed, transforming the exposure timing parameter to compensate for the rolling shutter effect and eliminate ranging errors.
Solution Approach 2:
The patent performs preliminary calculation of the required exposure timing adjustment before image capture. The control device calculates the timing adjustment amount based on predetermined baseline information and vehicle speed, then applies this adjustment in advance to synchronize the exposure timing of multiple cameras, preventing ranging errors before they occur.
2Measurement precision
If exposure timing is synchronized for rolling-shutter cameras, then ranging accuracy is improved, but control complexity increases
Solution Approach 1:
The patent implements a self-service mechanism where the camera system automatically calculates and adjusts its own exposure timing based on built-in parameters such as baseline distance and vehicle speed. The control device uses predetermined information to autonomously determine the timing adjustment amount, eliminating the need for complex external synchronization control.
Solution Approach 2:
The patent employs feedback by using the relationship between vehicle speed, baseline distance, and exposure timing to calculate the required adjustment. The system continuously monitors these parameters and adjusts the exposure timing accordingly, creating a closed-loop control mechanism that maintains synchronization without complex external intervention.
3Ease of manufacture
If stereo cameras are used instead of sensor fusion with LiDAR, then production cost is reduced, but the system cannot handle directions not monitored by stereo cameras
Solution Approach 1:
The patent makes monocular cameras universal by enabling them to perform three-dimensional information acquisition through timing-synchronized image capture. By applying the exposure timing adjustment technique to monocular cameras, the system allows any two cameras with overlapping fields of view to function as a stereo pair, expanding the system's versatility to cover all directions monitored by any camera pair.
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
This method effectively suppresses ranging errors by synchronizing the exposure timing of rolling-shutter type cameras, ensuring accurate three-dimensional information acquisition using a pair of still images captured by vehicle-mounted cameras.
Implementation Method 1
a camera that employs a rolling-shutter type image sensor such as a CMOS sensor (an image sensor that sequentially captures images by shifting exposure timing for each image capturing line on the light receiving surface)
Implementation Method 2
the distance to the ranging target around the vehicle (three-dimensional information) can be calculated using the method of triangulation by obtaining the parallax by mapping the same target portions in the left and right images captured by the left and right cameras
Implementation Method 3
obtaining the parallax by mapping the same target portions in the left and right images captured by the left and right cameras using, such as a pattern matching method
Data Source
AI summary
To provide a vehicle-mounted control device that suppress a ranging error by controlling an imaging start timing of a rolling-shutter type camera according to a situation when acquiring the three-dimensional information around the vehicle based on a pair of still images captured by a pair of the cameras including at least one rolling-shutter type camera. The vehicle-mounted control device communicates with a plurality of cameras including a first camera with a rolling-shutter type image sensor. The vehicle-mounted control device includes: a ranging unit that measures a distance to a ranging target using a plurality of images captured with a first camera and a second camera, the second camera being capable of capturing a same ranging target in at least part of an image capturing region of the first camera; and an exposure timing adjusting unit that adjusts an exposure timing of at least one of the first camera or the second camera based on a ranging position of at least one of the plurality of images.