12/23/2023 0 Comments Traffic light![]() ![]() Such techniques allow us to find trajectories faster.”ĭistributed optimization uses the computing resources of all the CAVs to dictate traffic flow, which the authors claim is both more efficient, and less likely to fall prey to communication failures. “In the new paper, we use distributed optimization techniques that allow utilizing the computational power of autonomous vehicles. “The latest concept mainly addresses the computational challenges we faced in the original concept,” explains Leila Hajibabai. However, that initial concept relied on a centralized computing approach, with the computer controlling the traffic light being responsible for receiving input from all approaching CAVs, making the necessary calculations, and then telling the CAVs exactly how they should proceed through the intersection. ![]() The white paper builds on earlier research first undertaken in 2020. Leila Hajibabai, assistant professor, Edward P Fitts Department of Industrial and Systems Engineering, NC State University Distributed optimization ![]() “ONE CONSTRUCTIVE COMMENT WE HAVE RECEIVED IS THAT WHITE IS NOT THE BEST CHOICE OF COLOR… THE WHITE PHASE IS JUST A TERM THAT WE USE FOR CONSISTENCY AND SIMPLICITY, BUT WE PREFER A NEW INDICATION RATHER THAN A NEW COLOR” What’s important is that there be a signal that is clearly identifiable by drivers.” And, just to be clear, the color of the ‘white light’ doesn’t matter. “We wanted to use portions of the cycle length, where autonomous vehicles could operate similarly to signal-free conditions, and the white phase makes that happen. “In transitioning from no automation to full autonomy, we still need to use traffic lights,” says Dr Hajbabaie. The white phase allows that.”ĭuring the white phase, each driver must follow the vehicle in front and not change lanes to pass it. Therefore, there is no need to show green, amber or red, only to let drivers know that autonomous vehicles are in charge at that time. The idea is that when enough CAVs are present, they can communicate with each other and traffic light controllers to negotiate a safe right of way for the group they are leading. “CAVs represent mobile controllers that can collaborate with traffic signal controllers to navigate groups of human-driven vehicles through the intersection. “The main idea is to utilize CAV capabilities to control traffic,” he says. The granting of some of the traffic flow control to AVs is described as “the mobile control paradigm” by Dr Hajbabaie. We will modify the approach based on these tests and then do real-world tests using our autonomous vehicles.” “The next step will be testing it in a driving simulator to see how drivers will react to the new signal indication and how they follow the vehicle in front. Real-world testing is also underway: “We are now making runs in our small-scale automated vehicle testbed,” explains Dr Hajbabaie. “We have run many hours of simulation and have used a typical intersection with various traffic volumes and autonomous vehicle penetration rates.” Fitts Department of Industrial and Systems Engineering. “We have modified its traffic light control logic and used it to simulate the movement of human-driven vehicles while we control CAVs with the optimization models we have developed,” notes Leila Hajibabai, a co-author of the paper, and assistant professor at NC State’s Edward P. The white phase was tested using PTV Vissim traffic simulation software. With 90% CAVs, we observed a 13% reduction in fuel consumption.” “For fuel consumption, when the autonomous vehicle market share is 10%, we observed a 1% reduction. “When 50% of traffic is comprised of autonomous vehicles, the white phase reduces travel delay by 10% in our test intersection,” he continues. “When autonomous vehicles are 10% of the traffic stream, the white phase reduces the travel delay by 3%,” adds Ramin Niroumand, first author of the paper and a PhD student at NC State. Even if the idea never reaches full adoption, it nevertheless brings new focus to the challenge of integrating the flow of CAVs with manually driven vehicles on our roads time through intersections and reduce fuel consumption: “We have compared our results with different benchmarks, but perhaps an interesting one is comparing the white phase concept to the same intersection with identical traffic volume and CAV penetration without the white phase,” says Dr Ali Hajbabaie. The scientists behind it have conducted hours of simulations that show the new approach could significantly improve travel A fourth, white traffic light could be the hottest new concept in traffic management right now. Researchers are carrying out some testing on a small-scale CAV testbed ![]()
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