A Procedure for the Derivation of a Schedule-Based Energy-Equivalent Driving Cycle for Urban Buses

Abstract

The present paper takes the lead from the long-lasting experience gained by the author on mathematical modeling of vehicle energy performances and on the calibration of those models based on real data acquired on buses in real operation. In particular, the paper focuses on a possible way to define a schedule-based energy-equivalent driving cycle which may have a number of applications (e.g., for buses’ performance prediction, propulsion systems choice and net optimization). Specific attention was given to energy-equivalency of the proposed driving cycles to the foreseeable real mission of the vehicles on their scheduled duty (e.g., mean inertial energy on play during vehicle Start and Stops, mean stops in between the arcs, mean vehicle speed and acceleration, etc.): The objective was in fact that of reproducing the same energy characteristics of the real vehicle mission in a simplified way. To this aim, the main energy characteristics of the expected mission were foreseen through a regressive interpolation of data coming from an extensive analysis of onboard measured data, based on independent variables (mean vehicle cruise speed and slope), which could be efficiently estimated by vehicle schedule. There could be a number of possible uses of the so-defined driving cycles (e.g., for buses’ performance prediction, propulsion systems choice and net optimization): All these applications will benefit from the precision of the cycles in predicting energy characteristics of the real vehicle use and will therefore be much more reliable than in usual practice (which normally makes reference to standardized bus cycles with very limited connection to expected vehicle use).