Fundamentals on Vehicle and Tyre Modelling

Abstract

Many books provide vehicle dynamics and tire dynamics equations. Most of them are either too complex or too simplified for global Vehicle Motion Control (VMC). This chapter is focusing on the couplings that exist between longitudinal, lateral and vertical dynamics at both the vehicle and tire level. The equations provided are simple but sufficient for global VMC. Several research papers and industrial patents tend to provide a control strategy for a standalone system. Simplified car models are taken into consideration from the beginning. As we are steering towards global VMC, more complex models are needed. Here, we start from complex equations that are simplified enough to facilitate control synthesis while capturing the required couplings for a coordinated control. Results show how this simplified global dynamics equations are close enough to more complex high-fidelity models. These equations should be therefore used for the next generation of global VMC.Car manufacturers and equipment suppliers are constantly proposing new attractive subsystems to stand out from their competitors. Recently, a large interest has been given particularly to automated vehicles. Automation promises indeed safer and smarter vehicles. Several researches have been carried out on one hand in robotic vision, sensor fusion, decision algorithms, big data management, and others. On the other hand, car manufacturers are looking closely on the over-actuation of the vehicle itself (Shyrokau & Wang, 2012;Soltani, 2014;Sriharsha, 2016). Indeed, giving the vehicle new features such as the ability of steering the rear wheels (Seongjin, 2015), distributing the brake torques or/and the engine torques differently between left and right tires (Siampis et al., 2013) and so on, can expand the vehicle's performance and generate new motion possibilities and car behaviors. This can be actually achieved provided that a global chassis control strategy can be designed.