Directional Dynamics of a Tractor-Semitrailer with Self-and Forced-Steering Axles

The influence of self– and forced-steering axles on the directional dynamics of a tractor-semitrailer is investigated through computer simulations. The dynamic charactenstics of a self-steering axle are analytically modeled and integrated to a three-dimensional nonlinear directional dynamic model of the vehicle. Two forced-steering algorithms relating the vehicle speed and response quantities to the angle of the wheels of the steerable axle are formulated, and integrated to the nonlinear directional dynamic model of the vehicle.Computer simulations are performed to determine the directional response characteristics of a tractor-semitrailer with self-and forced-steering axles for low as well as high speed maneuvers. The directional response characteristics of the vehicles with self- and forced-steering axles are discussed in view of the self-steering parameters and forced-steering gains, and compared to those of the vehicle with conventional axles.