Emission Constrained Eco-Driving and its HIL Validation

Eco-driving has received much attention as a simple method to improve fuel economy by suggesting appropriate speed and gear shifting profiles. In commercial applications it is used mainly directed to long haul heavy duty transportation on highways. Eco-driving, however, could offer more, in particular to improve emissions and/or other performance measures and be used for generic roads. Against this background, this paper presents such an extension in the form of a multi-objective optimal vehicle control strategy for country roads, and explores the factors influencing the trade-off between fuel consumption and emissions. Not surprisingly it turns out that considering emissions significantly alters the optimal velocity trajectory, but more surprisingly it turns out that the achievable performance is very sensitive to the choice of allowed accelerations and thus on curves, as limits on the acceptable lateral accelerations can lead to strong limits on the longitudinal speed. Simulation results are confirmed by a hardware in the loop (HIL) system based on a dynamical test bench (TB). The HIL system is on its turn validated through replicating measurements from a test car with a portable emission measurement system (PEMS) and the same engine as used on the TB. Their agreement confirms that the results obtained in simulation are indicative for the use in real situations.