On-board electric powertrain control for the compensation of the longitudinal acceleration oscillations caused by road irregularities

The drivability of a vehicle describes all the perceptions of a driver, including perceived safety and comfort. The latter one is mostly affected by road irregularities, involving uncomfortable variations in vertical and longitudinal accelerations of sprung and unsprung masses. While the vertical dynamics has been already fully studied, the longitudinal dynamics has not been completely explored yet. However, although smaller than the vertical acceleration oscillations, the longitudinal acceleration's variations oscillations are not negligible. The goal of this study is to develop, and to implement in real time, a pre-emptive non-linear model predictive control (NMPC), whose aim is to attenuate the oscillation of longitudinal acceleration by changing the motor torque requested by the driver. In particular, the controllers have been implemented on a full electric vehicle, which includes a realistic tire model for ride comfort simulation, characterised by three different architectures: the 4 in-wheel motors, 4 on-board motors and 2 on-board motors with open differential. The NMPCs’ performances have been evaluated and compared by considering four different key performance indicators (KPIs) along multiple manoeuvres, e.g. uneven road profile and step profile, at different speeds and required motor torques. Further analyses have been conducted to analyse the effect of some powertrain’s parameters of the 4 on-board configuration, such as motor time constant, equivalent inertia at the wheel, shaft stiffness and angular backlash, on the controller's capability. In the end, the controllers' capability to be implemented in real time is proved by using dSPACE MicroAutoBox II. The thesis' project has been developed in collaboration with the Centre of Automotive Engineering at the University of Surrey (UK). The content and the points of novelty of this research work are the subject for a future research paper. A colleague from "Università degli Studi di Pavia", Davide Lazzarini, and I were the engineers responsible for the development of this innovative research project. This activity has been supervised by Prof. Aldo Sorniotti and Prof. Umberto Montanaro, from "University of Surrey",Prof. Alessandro Vigliani, from "Politecnico di Torino", Prof. Antonella Ferrara, from "Università degli Studi di Pavia", and Pietro Stano, PhD student at "University of Surrey".