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While VDC systems usually operate on the engine torque and on brake pressures, new automotive applications try to use semi-active or active differentials in order to optimize the torque distribution on the wheels for traction maximization, driving comfort, stability and safety of the vehicle. The system presented in the paper comes out from the cooperation of Ferrari S.p.A. and Politecnico di Milano in the development of a new semi-active differential. In the paper a description of the vehicle dynamic control strategy, its development, and experimental results are given.

For passenger cars, individual tyre model parameters, used in vehicle models able to simulate vehicle handling behavior, are traditionally derived from expensive component indoor laboratory tests as a result of an identification procedure minimizing the error with respect to force and slip measurements. Indoor experiments on agricultural tyres are instead more challenging and thus generally not performed due to tyre size and applied forces. However, the knowledge of their handling characteristics is becoming more and more important since in the next few years, all agricultural vehicles are expected to run on ordinary asphalt roads at a speed of 80km/h. The present paper presents a methodology to identify agricultural tyres' handling characteristics based only on the measurements carried out on board vehicle (vehicle sideslip angle, yaw rate, lateral acceleration, speed and steer angle) during standard handling maneuvers (step-steers, J-turns, etc.), instead than during indoor tests.