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The paper analyses an undesired dynamic behaviour which occurs at the front suspension of a tilting motorcycle having two front wheels and a rear one. In particular, experimental data obtained on a first prototype of the vehicle have shown that the amplitude of the hop oscillation of the two front wheels becomes very high when the velocity of the three wheeler is about 85 km/h. In order to analyze the oscillations and to understand how to reduce them, a linear model of the front axle has been developed to estimate the eigenvectors and eigenvalues of the front suspension. Afterwards, two different ways to reduce the undesired oscillation are presented and evaluated. The obtained results show that, by the use of properly designed mass dampers, it is possible to greatly reduce the vibrations without affecting the handling behaviour of the vehicle. Finally, a multibody model allowed to analyze the effects of different sources of nonlinearities such as those due to the tire contact forces.

A ride comfort analysis of two-wheeled veichles is discussed in this work. A series of experimental tests were performed in relation to roads having different surface roughness; employed vehicles, differing on motorization, suspensions and wheel sizes, were instrumented with two axes (longitudinally and vertically oriented) accelerometers, fixed at the human-vehicle interfaces. Moreover, two axes accelerometers were also fixed to the wheel hubs, in order to record road inputs at each wheel. The comfort analysis, which was conducted following the international ISO 2631, allowed the influence of the primary vehicle suspension system to be investigated. In addition, a multibody model of the scooter-pilot system was built using Adams© code, for one of the employed vehicles, with the main aim of assessing the effectiveness of a dynamic simulation of ride comfort.

In this work the modal analysis of a three-wheeled tilting motorcycle is presented. This new kind of vehicle has two front wheels and a single rear wheel, but is driven like a common motorcycle. In order to study the stability of the system in straight running, two models have been developed: a simplified motorcycle model, with locked suspensions and rigid and thin tires and a more accurate model having 14 degrees of freedom, in which the stiffness and damping of suspensions and the radial stiffness of tires have been taken into account. In both models the frame has been considered as rigid and the driver was assumed to be fixed to the frame. A linear model with transient behaviour has been employed for describing the tire behaviour. A reference model of a two wheeler with similar inertial properties has been also developed for comparison.

This paper deals with the analysis of the handling behaviour of a novel three-wheeled motorcycle. This vehicle has two front steering wheels and a single rear wheel and can be driven much like a common two wheeler. In order to analyse the handling behaviour of such vehicle and to compare it to an ordinary two wheeler, an experimental campaign was conducted with the vehicle endowed with several transducers. Experimental tests included some classical handling manoeuvres. Concurrently, a simulation model was developed using a multi-body code. A simple logic was employed to drive the model; it consists in a roll follower and a longitudinal velocity follower. The main dynamic parameters obtained from simulations, such as the steering angle and steering torque are compared to the experimental data and discussed. The effect of the driving style on the manoeuvre is also analysed with reference to steering pad manoeuvres.