Patent ID: 8886400

Claim:
A method for determining a drawbar length of a trailer of a tractor vehicle, the tractor vehicle having a front-axle steering system for adjusting a front-axle steering angle, the method comprising: measuring with sensors an articulation angle between the trailer and the tractor vehicle, determining an estimated value for the drawbar length by an estimation method based on the measured articulation angle and based on the front-axle steering angle and movement variables represented by a speed and a yaw rate of the tractor vehicle, wherein the estimation method comprises: generating a sequence of estimation time windows having a beginning and an end, wherein the end of an estimation time window is defined by presence of predetermined conditions relating to dynamic movement variables of the tractor vehicle and the trailer, determining at the end of each estimation time window an estimated value of the drawbar length, successively determining from a current estimated value of the drawbar length, by statistical evaluation, statistical drawbar length estimates, each statistical drawbar length estimate having a respective quality measure, weighting each statistical drawbar length estimate with the respective quality measure, and successively determining final estimated values for the drawbar length from the weighted statistical drawbar length estimates.