INTRODUCTION During last years, interest towards hybrid and electric vehicles has been constantly growing pushed either by environmental concerns and by the continuous rising of oil price. Nowadays, different carmakers include hybrid vehicles among their offer and first full electric vehicles appeared on the market. An interesting vehicle layout allowed in this new generation of passenger cars, is represented by the use of four In-Wheel electric Motors (IWM, [ 1, 2]). Hybrid or electric vehicles with in-wheel motors offer in fact several advantages: interior spaciousness can be increased thus enlarging design freedom and room for components like batteries. Being the motor directly inside the wheel, no powertrain is required, this leading to the elimination of elements like drive shafts, gearboxes and differential. Drawbacks of IWM are ascribed to the increase of unsprung masses, which is widely accepted to worsen ride comfort and road-holding. Nevertheless recent studies have shown that performance deficit induced by increased unsprung masses could be largely recovered through design changes to suspension compliance bushings, top mounts, passive spring and damper characteristics, etc. [ 3],[11]. Besides layout advantages, IWM offer also interesting opportunities for the design of active control systems, in particular as far as lateral dynamics control is concerned. The presence of four independent electric motors allows in fact to individually control the driving/braking torque on each wheel; in other words, driving and braking torques can be easily distributed among the four wheels avoiding the complexity and the drawbacks of systems usually equipping today's cars. Limited slip differentials and semi-active differentials generate the yaw moment by differentiating the driving torque on the wheels; unfortunately in these systems the torque can only be transferred from the fastest wheel to the slowest one. On the other hand, a powertrain equipped with an active differential can overcome this limitation and can control both the amount of torque transfer and its direction [ 4]; unfortunately, the implementation of such a complicated device is associated with an increase of costs in terms of tuning, space and funding. Brake based systems (e.g. ESP) can instead stabilize the vehicle only with a significant reduction of its speed since the yaw moment is generated by applying differential braking to the four wheels [ 5, 6, 7]. Other systems like brake torque vectoring (BTV) obtain the desired yaw moment generating traction forces on one side of the vehicle (increasing the engine torque) and developing braking forces on the other side. In this way lateral dynamics of the vehicle can be controlled without reducing vehicle speed. The BTV system described in [ 8, 9] performs in fact as an active differential, though significant driving and braking torques should be developed and power dissipation in brakes may become a concern. In principle, torque vectoring is probably the most effective way to generate a yaw moment and, coming back to hybrid and electric vehicles, a layout based on four in-wheel motors seems particularly suitable for this application. Several applications can in fact be found in the literature [ 1,2,10,11]. The most of prosed control strategies defines torques to be applied by means of IWMs and aimed at improving vehicle handling performance through model-based controllers. This approach requires to estimate the actual motion of the vehicle Comparison of Torque Vectoring Control Strategies for a IWM Vehicle Edoardo Sabbioni, Federico Cheli, Michele Vignati, and Stefano Melzi Politecnico di Milano ABSTRACT In recent years, concerns for environmental pollution and oil price stimulated the demand for vehicles based on technologies alternative to traditional IC engines. Nowadays several carmakers include hybrid vehicles among their offer and first full electric vehicle