New Metrics for Quantifying the Energy Efficiency of Platoons in the Presence of Disturbances

Due to aerodynamic drag reduction, vehicles may have significant energy savings while platooning in close succession. However, when circumstances force active deceleration to maintain the platoon, such as during vehicle cut-ins or grade changes, the aerodynamic efficiency benefits may be undermined by losses in kinetic energy. In this work, a theoretical relationship is derived to correlate the amount of active deceleration a vehicle experiences with energy efficiency. The derived relationship is leveraged to analyze platooning data from the last vehicle in a class 8 vehicle platoon. The data include both two- and four-truck platoons operating under nine different truck-to-truck gap control strategies. Using J1939 CAN data and GPS-estimated grade profiles, off-throttle data were isolated and longitudinal acceleration is estimated as a function of grade using Kalman filtering. Using bounding regions to isolate coasting data from active deceleration data, the active deceleration losses were correlated to the energy consumption of the platooning vehicle. For the best correlated method, it was found that every kJ/kg·hr of active deceleration increased the platoon energy consumption by 9.09±0.59%, with an adjusted R₂ of 0.874. Suggestions for application of the method to platoons are made, and future work is discussed.