Comparing Methodologies for Using Vehicle Specific Power as a Powertrain Independent Measure of Platoon Energy Consumption for Implementation in a Predictive Control Strategy

Abstract

The combination of extensive fuel costs and outsized emissions impact make heavy duty trucking an ideal target for energy saving measures. To limit energy consumption in this transportation sector, platooning efforts have been explored to reduce aerodynamic drag. However, an impediment to platooning adoption is its poor ability to handle real world disturbances. One of the more effective methods to overcome disturbance sensitivity is the implementation of predictive control strategies, which can relieve concerns around the real-world platooning practicality. The performance impacts brought on by the introduction of a predictive longitudinal controller was explored herein. Predicative control with a cost function jointly optimizing for inter-vehicle distance and fuel utilization intentionally allowed more variation from the set following distance to reduce the severity and frequency of high load (torque/fuel) operational points. While current predictive controls strategies operate using fuel consumption predictions, this limits the applicability of these control strategies in vehicles with nonconventional powertrains. Therefore, developing a powertrain independent metric capable of replacing fuel rate in the predictive control cost functions would allow facilitate modularity in the platooning setup. An exploration of Vehicle Specific Power, VSP, as a powertrain independent platooning metric was conducted. This exploration compared three possible methods of replacing fuel rate with VSP: direct replacement, a mean sum of absolute VSP differences method, and a sum of positive VSP method. The sum of positive VSP was found to be more accurate and less cumbersome than other proposed methods. This method was also amenable to linearization. For these reasons, the sum of positive VSP was found to be the preferred powertrain independent energy parameter for usage in a future predictive longitudinal control strategies.