Roadside Camera-Radar Calibration for Low-Angle Vehicle Tracking
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Solution Overview
Problem
Existing traffic enforcement systems face challenges in accurately calibrating mobile devices due to varying operational conditions, which affect the precision of vehicle position determination, especially when cameras are positioned at low angles, leading to significant errors in vehicle positioning.
Innovation Solution
A method for calibrating traffic enforcement devices using a camera and radar to estimate and correct the camera's height and elevation parameters by aligning vehicle trajectories acquired by both systems, ensuring accuracy within a tenth of a degree for elevation and a hundredth of a meter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the camera is positioned at a low angle close to the ground, then the device can be operated at various locations including mobile deployments, but the uncertainty in elevation and height parameters significantly affects vehicle position determination accuracy
Solution Approach 1:
The patent uses feedback by comparing the vehicle trajectory measured by the camera with the trajectory measured by the radar, and using this comparison to iteratively adjust and refine the camera's position and orientation parameters until the trajectories align within acceptable tolerances
Solution Approach 2:
The patent replaces traditional mechanical calibration methods (such as total stations requiring fixed locations and complex setup) with an automated computational approach that uses trajectory comparison and iterative parameter adjustment to determine camera calibration
2Measurement precision
If traditional calibration methods using total stations are used, then position and orientation parameters can be determined, but the method is incompatible with mobile road traffic control devices that need to be moved to different locations
Solution Approach 1:
The system performs self-calibration by using its own radar and camera to measure the same vehicle trajectories and automatically compute the camera's position and orientation parameters without requiring external calibration equipment or fixed installation locations
Solution Approach 2:
The patent makes the calibration method universal by designing it to work with mobile devices that can be deployed at any location, eliminating the need for location-specific calibration procedures and enabling the same calibration approach to be used across different deployment scenarios
3Productivity
If the camera trajectory and radar trajectory are acquired at different frequencies, then data can be collected from both sensors, but the trajectories correspond to different acquisition times requiring synchronization
Solution Approach 1:
The patent performs preliminary interpolation of the trajectory data to resample both camera and radar trajectories at common time points before comparing them, ensuring that the synchronization is established before the calibration computation begins
Data Source
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AI summary
Method (500) for calibrating a road control device (101) comprising a camera (201) and a radar (202), the method (500) comprising the following steps: - estimating (501) the position and orientation parameters of the camera (201) and the radar (202) in a reference frame (O, x, y, z) linked to a lane (102a) of a road (102); - acquiring (502), by the camera (201) and the radar (202), the data relating to the trajectory of at least one of the same vehicle (103) on a lane (102a) of the road (102); - determine (503), on the one hand, a camera trajectory of the vehicle (103) in the frame (O, x, y, z) linked to the lane (102,a) of the road (102) from the data acquired by the camera (201) and the estimated position and orientation parameters, and on the other hand, a radar trajectory of the vehicle (103) in the frame (O, x, y, z) linked to the lane (102,a) of the road (102) from the data acquired by the radar (202) and the estimated position and orientation parameters;- calculate (504), from the camera trajectory and the radar trajectory, corrected values of at least some of the estimated position and orientation parameters of the camera (201), including an angle parameter, e, elevation parameter and a height parameter, h, of said camera (201).;