Drivability analysis of heavy goods vehicles

The paper presents linear and non-linear driveline models for Heavy Goods Vehicles (HGVs) in order to evaluate the main parameters for optimal tuning, when considering the drivability. The implemented models consider the linear and non-linear driveline dynamics, including the effect of the engine inertia, the clutch damper, the driveshaft, the halfshafts and the tires. Sensitivity analyses are carried out for each driveline component during tip-in maneuvers. The paper also analyses the overall frequency response using Bode diagrams and natural frequencies. It is demonstrated that the most basic model capable of taking into account the first order dynamics of the driveline must consider the moments of inertia of the engine, the transmission and the wheels, the stiffness and the damping properties of the clutch damper, driveshaft and half-shafts, and the tires (which link the wheel to the equivalent inertia of the vehicle). The results show that the first natural frequency of the drivetrain increases as a function of the half-shaft stiffness and the gear number, and the overall damping decreases as a function of the longitudinal slip stiffness of the tire. The vehicle payload has a significant effect not only on the steady-state acceleration, but also on the overall system dynamics (frequencies and damping).