A Torque Vectoring Control for Enhancing Vehicle Performance in Drifting

Abstract

When dealing with electric vehicles, different powertrain layouts can be exploited. Among them, the most interesting one in terms of vehicle lateral dynamics is represented by the one with independent electric motors: two or four electric motors. This allows torque-vectoring control strategies to be applied for increasing vehicle lateral performance and stability. In this paper, a novel control strategy based on torque-vectoring is used to design a drifting control that helps the driver in controlling the vehicle in such a condition. Drift is a particular cornering condition in which high values of sideslip angle are obtained and maintained during the turn. The controller is applied to a rear-wheel drive race car prototype with two independent electric motors on the rear axle. The controller relies only on lateral acceleration, yaw rate, and vehicle speed measurement. This makes it independent from state estimators, which can affect its performance and robustness.

A cooperative control strategy for yaw rate and sideslip angle control combining torque vectoring with rear wheel steering

“…Phase portrait analysis has proved to be a very effective tool for analyzing the dynamics of a nonlinear system as it immediately reveals the location and type of equilibria in the system and the region of attraction, or stable regions, about those equilibria. [18,29,31] showed that the fundamental planar instabilities critical to control problems such as ESP or stabilizing a drifting vehicle arise from the yaw and sideslip dynamics.…”

“…where on the left side the obtained control actions are the combined ones while on the right side the control actions provided by the PIs controllers are present. η are the efficiency factors that weights the controller action in combined control which are obtained by weighting the performance indexes as in equation (18).…”

“…increases the possibility of achieving this goal. Moreover, the shift from ICE (Internal Combustion Engine) to electric vehicles opens to additional control opportunities such as torque vectoring, which is enabled by independent electric motors ( [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]).…”

“…These plots in fact provide a graphical illustration of vehicle nonlinear dynamics, which is particularly useful in systems, which are described by two dominant states, such as vehicles running a turn on a planar surface. As a matter of fact, while ground vehicles have many degrees of freedom, the fundamental planar instabilities critical to control problems such as yaw rate control or stabilizing a drifting vehicle arise from the yaw and sideslip dynamics ( [18,[29][30][31]). In these cases, plotting the phase portraits allows to map equilibrium points locations and types and the range of possible trajectories in response to constrained or nonlinear control inputs.…”

“…In [31] the phase plane is used to study the coupling between vehicle and driver. In [18] the phase plane is instead used to study the effect of torque vectoring in controlling vehicle drift equilibria.…”