Use of the hypothetical lead (HL) vehicle trace: A new method for evaluating fuel consumption in automated driving

The regulation of fuel consumption and emissions around the world is based on standard drive (SD) cycles. Several autonomous or simple eco-driving methods of smoother driving and smaller acceleration and braking can violate the ± 2 MPH speed deviation regulation from the SD and hence they are currently not counted towards the vehicle fuel economy, even though they are acceptable from a traffic pattern perspective, namely following a vehicle at a safe and reasonable gap. This paper develops and suggests a prototypical vehicle velocity versus time trajectory that supersedes each SD cycle since the SD cycle is the vehicle trace from following a vehicle with the prototypical velocity trace. The prototypical velocity trace is named from now on as the Hypothetical Lead (HL) vehicle cycle. In essence, the HL cycle recreates the traffic conditions followed by the drivers of the standard drive cycles. Finally, the paper concludes with a demonstration of using the HL cycle for assessing the fuel economy benefits of autonomous following in relation to standard test cycles and limits on the following distances to ensure that the different drive traces follow the same prototypical traffic conditions in a reasonable and safe way for real world applications.