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.