On the Roll Angle Estimate via Inertial Sensors: Analysis of the Principal Measurement Axes

In this work it is proposed an analysis of the foremost inertial measurements to take into account for the estimate of the lean angle in two-wheeled vehicles. As it is well-known, the roll angle is a crucial variable in the dynamic of a two-wheeled vehicle, since it greatly affects the behaviour of the tire-road contact forces, especially in the lateral direction. Hence, the capability of providing a real time and reliable measure of such quantity allows to evaluate the dynamic properties of the vehicle and its tires and represents the enabling technology for the design of advanced ABS systems and stability control systems. The aim of the analysis proposed in this work is to identify which are the inertial measurements (accelerations and angular rates) that are strongly related to the lean angle and that can be used to estimate it in a urban path. Ideally, the measured lateral acceleration and the vertical angular velocity are the only crucial variables to estimate the tilt angle of a motorcycle, but in a real condition characterized by the presence of slopes, banks and variable speed, also the longitudinal measurement axis becomes relevant.