ON THE SIMULATION AND TESTING OF VEHICLE CHASSIS AND TRANSMISSION SYSTEMS

This thesis consists of two parts: • PART I is carried out in collaboration with the University of Surrey at their “Hardware-in-the-loop Drivetrain Test Facility”, with the aim of characterising a prototype of a novel electronic limited slip differential. Such a characterization is carried out by considering relevant performance parameters in a different steady-state conditions to test the differential in its two operating conditions: open differential and eLSD. In particular, a group of tests (straight conditions and turn conditions of the vehicle) are carried out in order to evaluate the behaviour of an open differential, focusing on the internal friction of the device and what they entail, namely its self-locking effect and therefore its efficiency. When the hydraulic clutch is actuated, instead, torque losses and torque distribution of the differential are studied. • In PART II the focus is on the integrated chassis control (ICC) system of the vehicle. This kind of control is achieved with an active control of traction/braking system, steering system, and suspensions system. Continuous studies on the cooperation of these controllers have the common goal of improving the vehicle stability and handling in a wide range of operating conditions. In this part a model-based procedure for the design of such controllers is presented with the aim to apply it to an active suspension system for yaw rate tracking, and heave, roll and pitch control. This study is carried out by developing a 6 degree of freedom vehicle model with active suspensions and the consideration of their kinematics. The model is then compared with a validated 8 degree of freedom vehicle model where the suspensions kinematics are neglected to assess the stability of the new model. Lastly a state-space formulation of the model is presented as a useful tool to extrapolate the necessary control laws for the implementation of an ICC.