Stability Investigation of Car-trailer Combinations considering Steering System Stiffness

The yaw instability of car-trailer combinations (CTCs) is indicated by the body sway of the towing car and/or the trailer. Experimental study shows that the steering system characteristics do have an influence on the stability of CTCs, although this effect is still not clear. The complexity of the dynamic coupling between the towing car and the trailer makes this problem more challenging. The influence of the steering system stiffness on the stability of CTCs is the focus of this paper. In this paper, a theoretical model in horizontal plane with 6 DOFs of CTCs has been established by Lagrange equation. The rotation of the steering column, the movement of the rack and the rotation of the steering wheel around the king pin are three DOFs considered in the steering system model. The tire property is considered as nonlinear. The dynamic stability of CTCs is indicated by the system dynamic critical speed. Through theoretical analysis and the simulation study, the effect chain between the steering system stiffness and the body sway of CTCs could be revealed.