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Vehicular platoon control can effectively achieve group consensus, improve vehicular running safety and increase road capacity. However, some constraints exist in practical situations due to the limitations of traffic environment in time-varying metrics (time-delay, packet-dropout or interruption) in wireless communication systems. In this work, a distributed model predictive control (MPC) algorithm is proposed for connected vehicle platoon with a focus on switching communication topologies and control strategy under abnormal communications. Firstly, the predecessor-leader following is selected as the basic communication topology, by which the switching communication topology and the desired vehicle spacing policy are established. Secondly, the platoon control algorithm of connected vehicles is established and a set of constraints is analyzed. Thirdly, the ${\mathcal{ L}}_{2} $ -norm string stability criterion and the asymptotic stability criterion are considered within the proposed MPC. Finally, a co-simulation platform for connected vehicle platoon is developed based on Prescan/Matlab/V2X communication simulator. In addition, the platoon control algorithm is tested in three traffic scenarios including normal communication, leading vehicle with abnormal communication and following vehicle with abnormal communication. The experiments demonstrate that the communication topologies in different communication environments can be switched well in real time through the proposed platoon control algorithm. In addition, the string stability, the consistency of vehicle spacing, speed and acceleration are proven to be guaranteed simultaneously. [ABSTRACT FROM AUTHOR]

This paper studies vehicle platooning with communication channels subject to random data loss. We focus on homogeneous discrete-time platoons in a predecessor-following topology with a constant time headway policy. We assume that each agent in the platoon sends its current position to the immediate follower through a lossy channel modeled as a Bernoulli process. To reduce the negative effects of data loss over the string stability and performance of the platoon, we use simple strategies that modify the measurement, error, and control signals of the feedback control loop, in each vehicle, when a dropout occurs. Such strategies are based on holding the previous value, dropping to zero, or replacing with a prediction based on a simple linear extrapolation. We performed a simulation-based comparison among a set of different strategies, and found that some strategies are favorable in terms of performance, while some others present improvements for string stabilization. These results strongly suggest that proper design of compensation schemes for the communications of interconnected multi-agent systems plays an important role in their performance and their scalability properties.

Connected and automated vehicles (CAVs) and regular human-piloted vehicles (RVs) will coexist in the near future. Research has indicated the feasibility of using CAVs to stabilize traffic flow and eliminate stop-and-go waves. In light of this, we develop distributed control schemes to stabilize mixed vehicular platoons by using CAV as the leading vehicle. We address several challenges, such as limited information perception capabilities of RVs, the uncertain actuation of human drivers, and external disturbances. Only local information from the preceding vehicle is used in the controllers. Modifications of the input-to-state string stability (ISSS) are established to cope with the uncertainty and disturbance characteristics while conditions for stability are derived. The proposed control schemes can attenuate the effect of disturbances while maintaining the ISSS property. The relationships between ISSS and other string stability concepts are clarified. Finally, numerical experiments are conducted to validate the effectiveness of the proposed platoon control schemes. [ABSTRACT FROM AUTHOR]

Automated and coordinated vehicle platoon driving is challenging as the complexity of vehicle control and the presence of unreliable wireless inter-vehicle communication. This subject has an interdisciplinary nature, involving control theories, vehicle dynamics, and communication. Due to the constant interaction between control logic and communication topology, a co-design approach for the controller and for reliable communication protocol becomes necessary. This paper describes the AddP-CACC - a consensus-based solution to vehicle platoons. The proposed solution turns the communication topology into a design parameter that dynamically reconfigures the controller. In addition, the controller automatically compensates for outdated information caused by network losses and delays. AddP-CACC was implemented in the PLEXE tool and was compared with other related works. Simulation results have shown the robustness and performance of the proposed solution in various scenarios that would include realistic propagation conditions with interference caused by other vehicles. The results have also evidenced the ability of the proposed solution to maintain a stable vehicular platoon by using different communication topologies, different vehicle flows, even in the presence of strong interferences, delays, and fading conditions. [ABSTRACT FROM AUTHOR]

The varying real-world road conditions (eg. slopes, speed limits) have great effects on the vehicle dynamics and fuel characteristics. The lack of consideration for these effects may lead to deteriorative fuel economy and even collisions. This paper presents a hierarchical control framework for a connected and automated vehicular platoon subject to time-vary uncertain dynamics and uniform communication delays. This control method minimizes the fuel consumptions and ensures the tracking performance on the premise of collision-free property. Firstly, a centralized ecological speed planning (CESP) algorithm based on dynamic programing (DP) is designed as the upper layer. This layer produces the fuel-optimal and feasible speed profiles, which can be followed by all vehicles, for the entire platoon based on the preview information of road conditions (eg. slopes, speed limits). Secondly, the distributed collision-free speed tracking control (DCST) method is proposed in the lower real-time control layer. The collision-free property is guaranteed by the uniform boundedness performance of the well-designed potential function of the spacing error. The convergences of all speed tracking errors are proved through barbalat's lemma. By modifying the desired spacing model, the application range of DCST is extended to the conditions with large initial deviations. Finally, the main theoretical results are verified through numerical simulations. [ABSTRACT FROM AUTHOR]

The platooning of connected and automated vehicles (CAVs) is expected to have a transformative impact on road transportation, e.g, enhancing highway safety, improving traffic efficiency, and reducing fuel consumption. One critical task of platoon control is to achieve string stability, for which various models and methods had been proposed. However, different types of definitions and analysis methods for string stability were proposed over the years and were not thoroughly compared. To fill these gaps, this paper aims to clarify the relationship of ambiguous definitions and various analysis methods, providing a rigorous foundation for future studies. A series of equivalences are summarized and discussed. The pros and cons of different analysis methods and definitions are discussed, too. All these discussions provide insights for practical selection of analyzing methods for vehicle platoons. [ABSTRACT FROM AUTHOR]