On the Energy Efficiency Potential of Multi-Actuated Electric Vehicles

The literature shows increasing interest in the energy efficiency aspects of electric vehicles with multiple actuators, e.g., capable of individual wheel torque and rear-wheel-steering control, and proposes controllers considering the relevant vehicle power losses. However, the available studies lack systematic analyses on: i) the energy saving potential of the individual actuation methods, and their combinations; and ii) the operating conditions in which a set of actuators is particularly effective in reducing power consumption. This paper targets the identified gap. After providing background on the relevant power losses, three forms of actuation, i.e., torque-vectoring through two or four electric powertrains, active suspensions for front-to-total anti-roll moment distribution control, and rear-wheel-steering, are explored through a set of simulations in quasi-steady-state conditions, by using an experimentally validated high-fidelity non-linear vehicle model. The analysis covers a range of vehicle speeds, longitudinal and lateral accelerations, and tire-road friction conditions, and determines: a) the most energy-efficient understeer characteristics, i.e., the loci of the front steering angle as a function of lateral acceleration providing the minimum power consumption, for each set of actuators; b) the energy-efficient actuations for achieving given understeer characteristics; and c) the power consumption penalty of each considered configuration with respect to the one with the complete set of actuators.