Patent ID: 6047231
Filing Date: 2000-04-04
Classification: B60K,B60T,B60W,G01B,G01P

Abstract:
In a vehicle which includes a front driveshaft for transferring motive power to a front set of wheels and a rear driveshaft for transferring motive power to a rear set of wheels, each of said wheels having an effective diameter, a method of monitoring the relative effective diameters of the tires, comprising the steps of:generating a front driveshaft value indicative of the rotational speed of said front driveshaft;generating a rear driveshaft value indicative of the rotational speed of said rear driveshaft;generating a difference value indicative of a difference between said front driveshaft value and said rear driveshaft value;generating a low pass filtered value according to the following relationship:Y.sub.1p =(1-.beta.)*U(k)+.beta.*Y.sub.1p (k-1)wherein Y.sub.1p is the low pass filtered value; .beta.=e.sup.-a*T ; a=2.pi.fc; fc=is a predetermined corner frequency of the filter; T=an amount of time elapsed between a prior execution of said method and the present execution of said method; U(k) corresponds to the difference value of the wheel speeds; and y(k) corresponds to the filtered value; andmonitoring the low pass filtered value for a predetermined period of time to determine if one of the wheels has a smaller effective diameter than the other wheels.