Omar Hanif

Vehicle platooning is a cooperative driving scenario in which a set of consecutive, connected and autonomous vehicles travel at the same speed while controlling their inter-vehicular distance. Organising traffic in platoons of vehicles can mitigate issues in road transport by improving safety, energy efficiency, and road usage. Vehicle platooning scenarios are enabled by communication across the fleet, allowing the design of distributed controllers to impose cooperative vehicle motion. In contrast to initial control strategies tailored for specific network topologies, the last decade has witnessed a substantial increase in vehicle platooning control solutions that treat the cooperative platoon motion as the synchronisation of a network of dynamic systems, thereby enabling their use across a wider range of topologies. Despite numerous publications in recent years, the literature lacks a comprehensive survey of network synchronisation methods for vehicle platooning. To fill this gap, this paper aims to review network synchronisation strategies proposed for controlling the longitudinal motion of vehicle platoons over the period 2013–2025, with particular focus on contributions from 2018 onwards. The literature on network-synchronisation-based vehicle platooning methods is reviewed within a four-component framework. Then, the most widely used families of distributed consensus controllers are analysed, and the ways in which heterogeneity, nonlinearities, delays, packet drops, external disturbances, and cyber attacks are accounted for and mitigated are examined, along with different types of closed-loop stability. The review also surveys approaches from the literature for validating and assessing synchronisation algorithms in vehicle platoons, covering both experimental and simulation studies, as well as the related simulation platforms. The review paper concludes by presenting research trends and gaps, as well as potential future directions.

Fractional-order controllers have been shown to be an effective solution for improving the tracking performance of closed-loop control systems in various engineering applications. However, the use of fractional-order solutions have only been marginally investigated for controlling platoons of vehicles. Hence, this paper proposes three novel distributed fractional-order controllers where the vehicle platooning control problem of a set of homogeneous followers, characterised by either second- or third-order systems, is reformulated as a consensus control problem. The resulting closed-loop systems are analysed using the root boundary locus approach to determine the region of control gains to ensure asymptotic closed-loop stability. Furthermore, the residual spacing errors to constant leader accelerations and disturbances are computed by analysing the error dynamics in the Laplace domain. The genetic algorithm is then employed for parameter optimisation within the stable region for different scenarios, and numerical analysis supports the theoretical findings and shows reduced tracking error when the fractional-order solutions replace their integer-order counterparts.