Tire-Ground Forces Estimation in a 4-Wheel Vehicle Using a Delayed Interconnected Cascade-Observer Structure*

The knowledge of tire-ground interaction forces is interesting for intelligent vehicles. However, tire forces transducers are expensive and not suitable for ordinary passengers cars. An alternative is to estimate these forces using common sensors. This paper presents an estimator structure capable of reconstructing tire-ground interaction forces in all directions. A delayed interconnected cascade-observer structure is proposed to eliminate mutual dependence between estimators. Observers are developed based on nonlinear vehicle dynamic models with the Extended Kalman Filter algorithm. The estimator is validated with experimental results. The results are also compared with an existent estimator of the literature.