Method for estimating the current gradient of the force-locking function

In the present method for estimating the current gradient of the force-locking function, which is determined by a longitudinal slip between wheel and ground, a model of the drive train and the contact between the wheel and the ground in the form of a differential equation system is provided in which the slope of the force-locking function as known parameters is included, performed with the model a model-based estimation and a necessary for estimating the excitation signal is superimposed on the set value of the motor torque, the drive response to this excitation signal by measuring a rotational speed in the drive train is detected. By these measures, reliable and simplified compared to the prior art estimate of the current slope is guaranteed.