Cooperative Eco-Driving for an All-Electric and Mixed Two-Vehicle Platoon Based on Pontryagin's Minimum Principle

Cooperative eco-driving (Co-ED) is a promising technology for improving vehicle efficiency through appropriate coordination. Additionally, platooning can significantly improve the vehicle's energy efficiency by reducing aerodynamic resistance. The optimal trajectory of the Co-ED vehicles in a platoon will be challenging to derive due to the high nonlinearity of the aerodynamic drag coefficient. Furthermore, although the electrification of vehicles has made rapid progress, the traffic on the road will still tend to be a mix of conventional vehicles (CVs) and electric vehicles (EVs) for a long time. It is critical to take the energy consumption characteristics of different vehicle types into account for a mixed platoon during Co-ED. This paper considers the platooning effects and heterogeneity of leading vehicles in two-vehicle platoons and utilizes Pontryagin's Minimum Principle (PMP) to derive the optimal speed trajectories for both homogeneous (all-electric) platoon and heterogeneous platoons (with different fuel types of vehicle). Simulation results from the proposed PMP-based Co-ED strategy show that the platooning effect has a noticeable impact on the Co-ED driving behaviors (particularly the intervehicle space and the transient performance). Simulation results also demonstrate that the same following EV will result in less energy consumption by 4.8% in an EV-led platoon under urban/suburban scenario and approximately the same energy consumption under an interstate scenario compared in a CV-led platoon.