A Driveability Study on Automated Longitudinal Vehicle Control

Abstract

Pulse and glide (PnG) is a longitudinal control strategy that operates vehicles in a more fuel-efficient way than driving at a constant speed. The pulse phase is an acceleration phase, followed by a deceleration, or glide, phase. Former research on PnG had in common that the acceleration profile during the pulse phase is chosen to operate the engine along the course of optimal engine efficiency. However, this optimal strategy will not be accepted by human drivers due to high acceleration values and sudden changes in acceleration. The purpose of this paper is to assess the driveability of the PnG based on the subjective evaluations from test drives and, as a result, to define a PnG operation that is noticeable only to the skeptical customers. The fuel savings of this PnG operation are simulated afterward. The results of this paper reveal that a PnG operation that is noticeable only to skeptical customers is reached if the acceleration value and the absolute values of the jerk are kept below the specific thresholds. Also, the duration of deceleration needs to be limited. Furthermore, the selection of the target gear after exiting sailing needs to be calibrated specifically for PnG to cope with the engine vibrations. Within the identified thresholds, the fuel savings of PnG are larger than 18% below 48 km/h and decrease gradually with increasing speed. Consequently, PnG can be implemented to the drivers' satisfaction, leading to significant fuel savings. Moreover, as we provide a general link between the acceleration and jerk levels and the corresponding ride comfort, the results can directly be implemented in the trajectory planning of further automated longitudinal vehicle control schemes to attain the desired ride comfort.