Estimation and Analysis of the Tire Pressure Effects on the Comportment of the Vehicle Center of Gravity

In the presented paper, the tire pressure and its influence on the vehicle centre of gravity are estimated and analysed. For that reason, a relation relating the tire pressure to the vertical force and the tire vertical deflection is proposed and validated by real measures. Basing on this proposed model, the tire pressure estimation is realized by estimating the vertical force and the tire vertical deflection. The vertical force is estimated using data issued from accelerations sensor. The tire vertical deflection is the difference between its initial radius and its radius when it is in contact with the ground and subjected to the vertical load. The initial radius is given by the constructor, and the other one is identified using a second orders sliding mode observer based on the super twisting algorithm (which observes the non measured states and identifies the effective radius). Simulations are made firstly in the absence of faults, results in this case are compared to the real measures, and secondly in the presence of faults, as an escape (sudden puncture) or a total failure in the tire pressure, in this case results are compared to that of a validated model. The analysis is made on the yaw angle and the yaw rate of the vehicle centre of gravity, the later is compared to a certain threshold which varies with the velocity and the coefficient of friction