Global vehicle trajectories and traffic parameters detecting method in expressway based on radar and vision sensor fusion

To meet the demand of smart expressways for a wide-range detection of traffic parameters in complex traffic environments, a global vehicle trajectories and traffic parameters detecting method was proposed based on the data fusion of millimeter-wave radar and vision sensor. Raw data was collected by millimeter-wave radars and vision sensors deployed on different roadside poles. Through spatio-temporal synchronization, association, fusion, and multi-object tracking of multi-source detection target data, an algorithm was designed for detecting vehicle trajectories in the local scene. An algorithm for detecting global vehicle trajectories in continuous scenes was designed by reconstructing vehicle spatio-temporal information and merging vehicle trajectories in continuous traffic scenes. A method for detecting traffic parameters based on global vehicle trajectories was designed through position, speed, and other microscopic motion information extracted from global vehicle trajectories. Experimental data was collected and manually labeled in a pilot section of the smart expressways and was used to validate the proposed method. Research results show that in vehicle detection task and trajectory tracking task, the overall vehicle detection accuracy of each local scene and multiple continuous traffic scenes is greater than 90%, and the deviation between the tracking trajectory position and the actual position of the vehicle is less than 0.2 m. In the traffic parameters detection task, the weighted average of mean absolute error between the detected vehicle's speed and the actual speed in the observation area is 3.41 km·h^-1, and the weighted average of mean absolute percentage error is 5.00%. The detection accuracies of traffic parameters such as space mean speed, traffic volume and traffic density can reach lane level, and the detection results are consistent with the real traffic phenomena in the expressway exit ramp and diverging area.