Virtual sensors, application to vehicle tire-road normal forces for road safety

The principal concerns in road safety are understanding and preventing risky situations. A close examination of accident data reveals that losing the vehicle control is responsible for a huge proportion of car accidents. Improving vehicle stabilization is possible when vehicle parameters are known. Unfortunately, some parameters like tire-road forces, which have a major impact on vehicle dynamics, are difficult to measure in a standard car. These data must therefore be observed or estimated. This study presents an estimation process for lateral load transfer and wheel-ground contact normal forces. The proposed method is based on the dynamic response of a vehicle instrumented with cheap, easy available standard sensors. The estimation process is composed of two parts: the main role of the first part is to estimate the oneside lateral load transfer, while in the second part we compare linear and nonlinear models for the estimation of vertical forces on the four wheels. Performances are tested using an experimental car in real driving situations. Experimental results show the potentiel of the estimation method.