Estimation of vehicle velocity based on suspension signals

An accurate estimation of the vehicle velocity is one of the greatest challenges in modern vehicle systems. The velocity is needed for the Antilock Braking System (ABS) and Traction Control System (TCS) as well as for the Electronic Stability Program (ESP) and cannot be measured directly. Using at least two fist sensors, which measure the vertical frequency component of a front wheel and the related rear wheel, the phase difference between both signals gives knowledge about the velocity of the vehicle. The presented algorithm is based on cross correlation function to estimate the velocity using the sensors described above. Different methods are described which improve both the resolution and the accuracy of the output signal v ref .