This paper proposes a distributed nonlinear consensus delay-dependent control algorithm for a connected vehicle (CV) platoon. In particular, considering that the behavior of the following vehicle is associated with the longitudinal inter-vehicle gap with respect to the preceding vehicle, a nonlinear function is designed to characterize the car-following interactions between CVs. Then, a nonlinear consensus algorithm is proposed by incorporating the car-following interactions and heterogeneous time delays. The delay-dependent convergence condition of the proposed control algorithm is analyzed using the Lyapunov-Krasovskii method, and an estimate of the delay bound is provided. Under the proposed algorithm, not only can the consensus of CVs be guaranteed but also the behavior of vehicles is consistent with traffic flow theory. Finally, an example using a 10-vehicle platoon is provided under three scenarios: no time delays, heterogeneous time delays, and homogeneous time delays. Results from extensive simulations verify the effectiveness of the proposed control algorithm in terms of the position, velocity, and acceleration/deceleration profiles.

This paper focuses on platoon control of multi-vehicle systems in a realistic vehicle-to-vehicle/vehicle-to-infrastructure (V2V/V2I, or V2X) communication environment. To this end, the communication probability of the beacon transmission is analyzed based on the carrier sense multiple access with collision avoidance (CSMA/CA) mechanism. Then, a new car-following model is proposed by considering the communication probability to capture the car-following behavior of connected vehicles (CVs) equipped with V2X communications. The stability of the proposed car-following model is analyzed using the perturbation method. In addition, a nonlinear consensus-based longitudinal control algorithm is designed by considering the interactions between CVs, and an artificial function-based lateral control algorithm is presented. The convergence of the longitudinal and lateral control algorithms is analyzed using the Hurwitz stable theorem and Lyapunov technique, respectively. Also, the string stability of the vehicular platoon is performed based on the infinity-norm method. Finally, field experiments are conducted using four CVs under the scenarios of platoon forming, vehicle merging, and vehicle diverging. The results verify the effectiveness of the proposed method in terms of the trajectory and velocity profiles.

This paper investigates formation control protocols for autonomous vehicular strings with vehicle-to-vehicle (V2V) communication connections. To this end, a four-layer framework is first proposed to illustrate the cooperative mechanism within and across strings. Then, cooperative control protocols are designed based on vehicle role, i.e., leader or follower, in vehicular multi-string. In particular, longitudinal controllers are designed for single string and multiple strings by incorporating inter-vehicle gap and velocity difference of the follower vehicle with respect to the preceding vehicle and the lead vehicle. In addition, lateral controllers are proposed for single string and multiple strings based on the artificial function method. The proposed protocols ensure that follower vehicles asymptotically track the leader within each string, while different vehicular strings can form a desired platoon pattern. The study further analyzes the stability and consensus of the proposed control protocols using the Routh-Hurwitz stable criterion and the Lyapunov technique. Numerical experiments are performed for two cooperative mechanisms--parallel and serial. Results from numerical experiments illustrate the effects of the proposed control protocols on road throughput and demonstrate their effectiveness for position and velocity consensuses.

This paper proposes a distributed integral-sliding-mode (ISM) control strategy for cooperative braking control of a connected vehicle platoon with a focus on the car-following interactions between vehicles. In particular, a linear controller considering the position and velocity of the lead vehicle as well as the braking force is proposed for the leader, while a constant-time-headway-policy-based ISM controller incorporating the car-following interactions, the spacing error, velocity difference, and external disturbances is developed for the followers. In addition, the convergence for the ISM controller is rigorously analyzed using the Lyapunov technique. Furthermore, the string stability of the platoon is analyzed using the transfer function method. Finally, extensive analyses are conducted using numerical and field experiments. Results verify the effectiveness of the proposed control strategy with respect to the position, velocity, deceleration, and spacing error profiles.