Lateral Platooning Control with Precise Path Tracking and Strong Disturbance Suppression Performance

Abstract

There have been numerous studies on stable platooning, but almost all of them have been on the longitudinal stability problem, wherein, without sufficient longitudinal stability, traffic congestion might occur more frequently than in traffic consisting of manually driven vehicles. Failure to solve this problem would reduce the value of autonomous driving. Recently, some researchers have begun to tackle the lateral stability problem, anticipating shortened intervehicle distances in the future. Here, the intervehicle distance in a platoon should be shortened to improve transportation efficiency. However, if an obstacle to be avoided exists, the following vehicles might have difficulty finding it quickly enough if the preceding vehicle occludes it from their sensors. Also, longer platoons improve transportation efficiency because the number of gaps between platoons is reduced. Hence, in this study, the lateral stability of platoons consisting of autonomous vehicles was analyzed for not only determining how to track the preceding vehicle when there are lateral movements but also suppressing unintentional lateral movement caused by disturbances affecting the vehicles in the platoon. The analytical results indicate that it is not realistic to expect that a single gain controller can both track the reference path to avoid an obstacle and suppress the lateral movement caused by a disturbance to long platoons of 10 vehicles or more. On the basis of these results, a new lateral control strategy was developed that has both good tracking performance for avoiding obstacles and a capability of suppressing harmful movements of vehicles following the one affected by the disturbance. This strategy works by varying the gain depending on the estimated disturbance. A simulation was conducted to examine its effect on platoons consisting of 10 vehicles.