ABSTRACT
Vehicle handling and stability performances are of great importance high performance sport cars. To reach these targets, very high standards of performance all the more prestigious vehicle companies have improved a lot the kinematics and compliance of the front and rear suspensions, together with the tire characteristics development. Normally the improvements have been obtained working on existing suspensions without adding any active systems able to change the suspension kinematics and compliances. The only exception has been some suspension rework of 4 wheel steering system studied in the early 80ies years, that is an active system able to change the toe angle of the rear suspension wheels. This solution has not obtained a significant success also in the market of very prestigious cars because could not reach the target performance improvement of driving requested by the customer. The proposed research work is innovative because instead to change actively the wheel toe angle it applies a solution to change the wheel camber angle through the geometry of the rear suspension. The proposed system uses two separated electro mechanical actuators, one per wheel, in place of two existing rear suspension links.
A Sensor Signal Processing Model has been developed to estimate the vehicle states and calculating tire-road contact forces and vehicle sideslip angle. The methodological approach uses the equations of motion of the chassis applying the fundamental principles of classical physics: Newtonian method and Euler angles. In parallel a 15 dof (degrees of freedom) preview vehicle model has been used to achieve a high fidelity simulation vehicle dynamics. The selected software is LMS.Amesim to handle complex real-time 3D-1D mechatronic systems without any simplified conceptual models. The vehicle control logic is based on the continuous updating of the preview vehicle model by the controller sensors information network, which makes the model forecast behaviour closer to the real one and improve comfort and linearity of the vehicle response.
