Torque Vectoring in Hybrid Vehicles with In-Wheel Electric Motors: Comparing SMC and PID control

Electrification is a main trend in the automotive industry and in-wheel electric motors are among the underdeveloped yet promising technologies. The presence of multiple independent traction sources permits the implementation of innovative active systems and control strategies. This paper explores the possibility of a torque vectoring system applied to a FWD hybrid electric compact vehicle with two in-wheel electric motors in the rear axle and a thermal engine in the front axle. A 14 degrees of freedom co-simulation model of the vehicle is presented, developed to reproduce faithfully the non-linearities of the vehicle dynamics phenomena. Two control strategies are compared: a PID controller and a Sliding Mode Control architecture. Both achieve promising results in terms of lateral dynamics when compared to the baseline hybrid version, however the first order SMC chattering induces undesirable vibrations that undermine its potential when the vehicle is close to limit adherence condition. The effects of delays and hysteresis bands are analyzed and discussed as well as future developments of the research.