A New Approach for Estimating Tire-Road Longitudinal Forces for a Race Car

In vehicle dynamics, the determination of the tire-road interaction forces plays a fundamental role in the analysis of vehicle behavior. This paper proposes a simple yet effective approach to estimate longitudinal forces. The proposed approach: i) is based on equilibrium equations; ii) analyses the peculiarities of driving and braking phases; iii) takes into account the interactions between vehicle sprung mass and unsprung mass. The unsprung mass is often neglected but that might lead to significant approximations, which are deemed unacceptable in performance or motorsport environments. The effectiveness of the proposed approach is assessed using experimental data obtained from a high performance racing car. Results show that the proposed approach estimates tire longitudinal forces with differences up to 10% when compared against a simpler formulation which uses only the overall mass of the vehicle. Therefore the distinction among vehicle sprung and unsprung masses, which is likely to be an easily obtainable piece of information in motorsport environments, is exploited in this approach to provide significant benefits in terms of longitudinal force estimation, ultimately aimed at maximizing vehicle performance.