Quantifying the Energy Impact of Autonomous Platooning-Imposed Longitudinal Dynamics

Platooning has produced significant energy savings for vehicles in a controlled environment. However, the impact of real-world disturbances, such as grade and interactions with passenger vehicles, has not been sufficiently characterized. Follower vehicles in a platoon operate with both different aerodynamic drag and different velocity traces than while driving alone. While aerodynamic drag reduction usually dominates the change in energy consumption for platooning vehicles, the dynamics imposed on the follow vehicle by the lead vehicle and exogenous disturbances impacting the platoon can negate aerodynamic energy savings. In this paper, a methodology is proposed to link the change in longitudinal platooning dynamics with the energy consumption of a platoon follower in real time. This is accomplished by subtracting a predicted acceleration from measured longitudinal acceleration. The real-time consumption calculation methodology is evaluated using data from simulated and experimental platoons. The proposed methodology allows active deceleration losses to be calculated for a platoon follower in real time and is a development of the active deceleration theory presented by the authors in SAE Paper 2022-01-0526. In simulation, energy losses calculated by the method were within 5% of the true value and were robust to errors in modeled aerodynamic drag. As for the experimental results, the method agreed with the prior procedure of SAE Paper 2022-01-0526, which required extensive datasets and could only be completed as a post-processing routine. This novel methodology provides an important new feedback metric for platoon operators, and makes it possible to analyze real-time platooning benefit while the platoon is on the road.