Modeling and observer design for two wheeled vehicules : Application to road-tire adherence estimation and stability analysis in curves

Accidents involving motorbikes constitute an important part of the overall road accidents
in France, and death rates reach 20%, efforts to reduce them led to an increase in research in
stability analysis of these vehicles. Corners and curves are the situations that lead the most to
instability, as they make the driver make control decisions that might turn out to be counter
intuitive. And as the study and analysis of these motorcycle’s critical driving situations, falls
and accidents, are difficult to be described analytically because of the simultaneity of different
and complex phenomena which make the dynamics quite elaborate. In this work, a model
able to describe the strong non-linearities conveyed by the complex dynamic of a two-wheeled
vehicle in curves, is presented. The model takes into account the necessary components needed
to accurately calculate the adherence, and thus use a state observer for difference situations, to
estimate it in curves, along with the forces involving the tire-road contact dynamics. A stability
analysis in these situations has been done for different critical variables along with the forward
speed. The ultimate objective being the synthesis of an alert system in case of instability.