Driver Monitoring Camera Calibration via Steering Angle Adaptation
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Solution Overview
Problem
Driver monitoring cameras often malfunction due to the face of the driver being cut by the image edge, especially when the camera is mounted on the steering wheel, leading to incorrect driver state recognition and operational issues, as the relationship between the camera and vehicle coordinate systems changes with the tilting angle of the steering wheel.
Innovation Solution
An apparatus and method that includes a camera with a control unit to detect face and background features, adjust camera position, and calibrate extrinsic parameters, featuring a display unit to show face position and a reflecting body for angle adjustment, automatically calibrating the line-of-sight based on vehicle state inputs such as direction indication or speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the camera is mounted on the steering wheel to enable driver monitoring, then the camera can capture driver images, but the face of the driver may be cut by the image edge due to steering wheel tilting angle changes
Solution Approach 1:
The patent implements dynamic calibration of the camera coordinate system relative to the vehicle coordinate system based on detected steering wheel angles. The control unit stores multiple calibration data sets corresponding to different steering angles and selects the appropriate calibration data based on the current steering angle, allowing the camera to adapt its field of view and coordinate system dynamically as the steering wheel tilts, thereby preventing the driver's face from being cut off by image edges.
2Ease of manufacture
If the camera mounting position is fixed to simplify installation, then the installation process is simple, but the field of view is limited and the driver's face may be cut by the image edge
Solution Approach 1:
The patent maintains a fixed camera mounting position for ease of installation but dynamically adjusts the effective field of view through coordinate system calibration. By storing and applying calibration data corresponding to different steering angles, the system virtually expands the usable field of view to always include the driver's face, regardless of the fixed physical mounting position or steering wheel angle.
3Measurement precision
If manual calibration procedures are used to adjust camera position, then accurate face detection can be achieved, but the calibration process becomes complex and time-consuming
Solution Approach 1:
The patent implements automatic calibration where the control unit detects the steering wheel angle, retrieves the corresponding calibration data from storage, and applies it to adjust the camera coordinate system automatically. This self-calibrating system eliminates the need for manual adjustment procedures, achieving accurate face detection across different steering angles while keeping the calibration process simple and rapid.
Solution Approach 2:
The patent performs preliminary calibration during the manufacturing or initial setup phase, storing calibration data for multiple steering wheel angles in the control unit. This pre-stored calibration data enables the system to automatically adapt to different steering angles during operation without requiring real-time manual calibration, thereby simplifying the operational process while maintaining high detection accuracy.
4Device complexity
If the camera coordinate system is fixed relative to the vehicle to simplify processing, then the processing is simple, but the relationship between camera and vehicle coordinate systems changes with steering wheel angle
Solution Approach 1:
The patent implements a dynamic coordinate system transformation where the camera coordinate system is calibrated relative to the vehicle coordinate system based on the detected steering wheel angle. The control unit stores multiple calibration data sets and selects the appropriate one based on the current steering angle, allowing the coordinate system relationship to adapt dynamically while maintaining processing efficiency through pre-stored transformation parameters.
Data Source
AI summary
An apparatus for calibrating a driver monitoring camera may include: a camera configured to capture an image of a driver's face; a control unit configured to receive the captured image from the camera, and detect the face to determine a face position; and a display unit configured to display the determination result of the face position by the control unit.