In vehicle truck steering-system modeling and validation

In this paper a multi-body 44-DOF tractor semi-trailer model is coupled to a 4-DOF steeringsystemwhich includes friction and hydraulic power-steering. An extended wheel hub geometry is used to provide the correct feedback torque from the wheels. A tie-rod with stiffness has been included to connect left and right. An instrumented tractor semi-trailer is used to verify the steering-system model predictions during driving. The focus lies on the prediction of the steering-wheel torque and the vehicle velocity and steering-wheel angle are prescribed as an input for the simulation. Two tests are discussed in this paper, a J-turn at 80 km/h and sinusoidal steering-wheel input with a frequency of 0.4 Hz at 65 km/h. The comparison of the measured signals and the predicted values shows that the steering-system model is accurate. The non-linearities caused by friction and hydraulic assistance system can clearly be seen in both the measurement and the simulation