Monitoring of the friction coefficient between tyre and road surface

The knowledge of the friction coefficient between tyre and road surface is the central part of vehicle longitudinal and lateral control. For this purpose a friction monitoring system is developed using nonlinear and hear mathematical models to describe the p-slip characteristics and to compute the dynamic wheel loads and longitudinal tyre forces. A recursive least squares estimator calculates the parameters of the p-slip characteristics on-line and on-board for use in control systems. deceleration manoeuvres. The second algorithm consists of the evaluation of the longitudinal force "backwards" by means of a dynamic model tor the vehicle longitudinal motion. With regard to the desired on-line calculation of the friction coefficient in real-time, a recursive least squares algorithm is proposed to estimate one typical coefficient of the tyre-road-system. The estimates of the actual friction coefficient are shown during a special driving cycle whereby hydroplaning occured.